comedi disabled on ppc (doesn't build)

[packages/kernel.git] / kernel-aufs2.patch

diff --git a/Documentation/ABI/testing/debugfs-aufs b/Documentation/ABI/testing/debugfs-aufs
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+What:          /debug/aufs/si_<id>/
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               Under /debug/aufs, a directory named si_<id> is created
+               per aufs mount, where <id> is a unique id generated
+               internally.
+
+What:          /debug/aufs/si_<id>/xib
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               It shows the consumed blocks by xib (External Inode Number
+               Bitmap), its block size and file size.
+               When the aufs mount option 'noxino' is specified, it
+               will be empty. About XINO files, see
+               Documentation/filesystems/aufs/aufs.5 in detail.
+
+What:          /debug/aufs/si_<id>/xino0, xino1 ... xinoN
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               It shows the consumed blocks by xino (External Inode Number
+               Translation Table), its link count, block size and file
+               size.
+               When the aufs mount option 'noxino' is specified, it
+               will be empty. About XINO files, see
+               Documentation/filesystems/aufs/aufs.5 in detail.
+
+What:          /debug/aufs/si_<id>/xigen
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               It shows the consumed blocks by xigen (External Inode
+               Generation Table), its block size and file size.
+               If CONFIG_AUFS_EXPORT is disabled, this entry will not
+               be created.
+               When the aufs mount option 'noxino' is specified, it
+               will be empty. About XINO files, see
+               Documentation/filesystems/aufs/aufs.5 in detail.
diff --git a/Documentation/ABI/testing/sysfs-aufs b/Documentation/ABI/testing/sysfs-aufs
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+What:          /sys/fs/aufs/si_<id>/
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               Under /sys/fs/aufs, a directory named si_<id> is created
+               per aufs mount, where <id> is a unique id generated
+               internally.
+
+What:          /sys/fs/aufs/si_<id>/br0, br1 ... brN
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               It shows the abolute path of a member directory (which
+               is called branch) in aufs, and its permission.
+
+What:          /sys/fs/aufs/si_<id>/xi_path
+Date:          March 2009
+Contact:       J. R. Okajima <hooanon05@yahoo.co.jp>
+Description:
+               It shows the abolute path of XINO (External Inode Number
+               Bitmap, Translation Table and Generation Table) file
+               even if it is the default path.
+               When the aufs mount option 'noxino' is specified, it
+               will be empty. About XINO files, see
+               Documentation/filesystems/aufs/aufs.5 in detail.
diff --git a/Documentation/filesystems/aufs/README b/Documentation/filesystems/aufs/README
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+
+Aufs2 -- advanced multi layered unification filesystem version 2
+http://aufs.sf.net
+Junjiro R. Okajima
+
+
+0. Introduction
+----------------------------------------
+In the early days, aufs was entirely re-designed and re-implemented
+Unionfs Version 1.x series. After many original ideas, approaches,
+improvements and implementations, it becomes totally different from
+Unionfs while keeping the basic features.
+Recently, Unionfs Version 2.x series begin taking some of the same
+approaches to aufs1's.
+Unionfs is being developed by Professor Erez Zadok at Stony Brook
+University and his team.
+
+This version of AUFS, aufs2 has several purposes.
+- to be reviewed easily and widely.
+- to make the source files simpler and smaller by dropping several
+  original features.
+
+Note: it becomes clear that "Aufs was rejected. Let's give it up."
+According to Christoph Hellwig, linux rejects all union-type filesystems
+but UnionMount.
+<http://marc.info/?l=linux-kernel&m=123938533724484&w=2>
+
+Through this work, I found some bad things in aufs1 source code and
+fixed them. Some of the dropped features will be reverted in the future,
+but not all I'm afraid.
+Aufs2 supports linux-2.6.27 and later. If you want older kernel version
+support, try aufs1 from CVS on SourceForge.
+
+
+1. Features
+----------------------------------------
+- unite several directories into a single virtual filesystem. The member
+  directory is called as a branch.
+- you can specify the permission flags to the branch, which are 'readonly',
+  'readwrite' and 'whiteout-able.'
+- by upper writable branch, internal copyup and whiteout, files/dirs on
+  readonly branch are modifiable logically.
+- dynamic branch manipulation, add, del.
+- etc...
+
+Also there are many enhancements in aufs1, such as:
+- keep inode number by external inode number table
+- keep the timestamps of file/dir in internal copyup operation
+- seekable directory, supporting NFS readdir.
+- support mmap(2) including /proc/PID/exe symlink, without page-copy
+- whiteout is hardlinked in order to reduce the consumption of inodes
+  on branch
+- do not copyup, nor create a whiteout when it is unnecessary
+- revert a single systemcall when an error occurs in aufs
+- remount interface instead of ioctl
+- maintain /etc/mtab by an external command, /sbin/mount.aufs.
+- loopback mounted filesystem as a branch
+- kernel thread for removing the dir who has a plenty of whiteouts
+- support copyup sparse file (a file which has a 'hole' in it)
+- default permission flags for branches
+- selectable permission flags for ro branch, whether whiteout can
+  exist or not
+- export via NFS.
+- support <sysfs>/fs/aufs and <debugfs>/aufs.
+- support multiple writable branches, some policies to select one
+  among multiple writable branches.
+- a new semantics for link(2) and rename(2) to support multiple
+  writable branches.
+- no glibc changes are required.
+- pseudo hardlink (hardlink over branches)
+- allow a direct access manually to a file on branch, e.g. bypassing aufs.
+  including NFS or remote filesystem branch.
+- and more...
+
+Currently these features are dropped temporary from this version, aufs2.
+See design/08plan.txt in detail.
+- test only the highest one for the directory permission (dirperm1)
+- show whiteout mode (shwh)
+- copyup on open (coo=)
+- nested mount, i.e. aufs as readonly no-whiteout branch of another aufs
+  (robr)
+- statistics of aufs thread (/sys/fs/aufs/stat)
+- delegation mode (dlgt)
+  a delegation of the internal branch access to support task I/O
+  accounting, which also supports Linux Security Modules (LSM) mainly
+  for Suse AppArmor.
+- intent.open/create (file open in a single lookup)
+
+Features or just an idea in the future (see also design/*.txt),
+- reorder the branch index without del/re-add.
+- permanent xino files for NFSD
+- an option for refreshing the opened files after add/del branches
+- 'move' policy for copy-up between two writable branches, after
+  checking free space.
+- O_DIRECT
+- light version, without branch manipulation. (unnecessary?)
+- copyup in userspace
+- inotify in userspace
+- readv/writev
+- xattr, acl
+
+
+2. Download
+----------------------------------------
+Kindly one of aufs user, the Center for Scientific Computing and Free
+Software (C3SL), Federal University of Parana offered me a public GIT
+tree space.
+
+There are three GIT trees, aufs2-2.6, aufs2-standalone and aufs2-util.
+While the aufs2-util is always necessary, you need either of aufs2-2.6
+or aufs2-standalone.
+
+The aufs2-2.6 tree includes the whole linux-2.6 GIT tree,
+git://git.kernel.org/.../torvalds/linux-2.6.git.
+And you cannot select CONFIG_AUFS_FS=m for this version, eg. you cannot
+build aufs2 as an externel kernel module.
+If you already have linux-2.6 GIT tree, you may want to pull and merge
+the "aufs2" branch from this tree.
+
+On the other hand, the aufs2-standalone tree has only aufs2 source files
+and a necessary patch, and you can select CONFIG_AUFS_FS=m. In other
+words, the aufs2-standalone tree is generated from aufs2-2.6 tree by,
+- extract new files and modifications.
+- generate a single patch file from modifications.
+- generate a ChangeLog file from git-log.
+- commit the files newly and no log messages. this is not git-pull.
+
+Both of aufs2-2.6 and aufs2-standalone trees have a branch whose name is
+in form of "aufs2-xx" where "xx" represents the linux kernel version,
+"linux-2.6.xx".
+
+o aufs2-2.6 tree
+$ git clone --reference /your/linux-2.6/git/tree \
+       http://git.c3sl.ufpr.br/pub/scm/aufs/aufs2-2.6.git \
+       aufs2-2.6.git
+- if you don't have linux-2.6 GIT tree, then remove "--reference ..."
+$ cd aufs2-2.6.git
+$ git checkout origin/aufs2-xx # for instance, aufs2-27 for linux-2.6.27
+                               # aufs2 (no -xx) for the latest -rc version.
+
+o aufs2-standalone tree
+$ git clone http://git.c3sl.ufpr.br/pub/scm/aufs/aufs2-standalone.git \
+       aufs2-standalone.git
+$ cd aufs2-standalone.git
+$ git checkout origin/aufs2-xx # for instance, aufs2-27 for linux-2.6.27
+                               # aufs2 (no -xx) for the latest -rc version.
+- apply "aufs2-standalone.patch" to your kernel source files.
+
+o aufs2-util tree
+$ git clone http://git.c3sl.ufpr.br/pub/scm/aufs/aufs2-util.git \
+       aufs2-util.git
+$ cd aufs2-util.git
+- no particular tag/branch currently.
+
+
+3. Configuration and Compilation
+----------------------------------------
+For aufs2-2.6 tree,
+- enable CONFIG_EXPERIMENTAL and CONFIG_AUFS_FS.
+- set other aufs configurations if necessary.
+
+For aufs2-standalone tree,
+- enable CONFIG_EXPERIMENTAL and CONFIG_AUFS_FS, you can select =m.
+- edit fs/aufs/config.mk and set other aufs configurations if necessary.
+
+And then,
+- build your kernel (or a module) by "make"
+- install it and reboot your system
+- read README in aufs2-util, build and install it
+
+
+4. Usage
+----------------------------------------
+At first, make sure aufs2-util are installed, and please read the aufs
+manual, ./Documentation/filesystems/aufs/aufs.5.
+$ man -l aufs.5
+
+And then,
+$ mkdir /tmp/rw /tmp/aufs
+# mount -t aufs -o br=/tmp/rw:${HOME}=ro none /tmp/aufs
+
+Here is another example. The result is equivalent.
+# mount -t aufs -o br=/tmp/rw:${HOME} none /tmp/aufs
+  Or
+# mount -t aufs -o br:/tmp/rw none /tmp/aufs
+# mount -o remount,append:${HOME} /tmp/aufs
+
+Then, you can see whole tree of your home dir through /tmp/aufs. If
+you modify a file under /tmp/aufs, the one on your home directory is
+not affected, instead the same named file will be newly created under
+/tmp/rw. And all of your modification to a file will be applied to
+the one under /tmp/rw. This is called the file based Copy on Write
+(COW) method.
+Aufs mount options are described in aufs.5.
+
+Additionally, there are some sample usages of aufs which are a
+diskless system with network booting, and LiveCD over NFS.
+See sample dir in CVS tree on SourceForge.
+
+
+5. Contact
+----------------------------------------
+When you have any problems or strange behaviour in aufs, please let me
+know with:
+- /proc/mounts (instead of the output of mount(8))
+- /sys/module/aufs/*
+- /sys/fs/aufs/* (if you have them)
+- /debug/aufs/* (if you have them)
+- linux kernel version
+  if your kernel is not plain, for example modified by distributor,
+  the url where i can download its source is necessary too.
+- aufs version which was printed at loading the module or booting the
+  system, instead of the date you downloaded.
+- configuration (define/undefine CONFIG_AUFS_xxx)
+- kernel configuration or /proc/config.gz (if you have it)
+- behaviour which you think to be incorrect
+- actual operation, reproducible one is better
+- mailto: aufs-users at lists.sourceforge.net
+
+Usually, I don't watch the Public Areas(Bugs, Support Requests, Patches,
+and Feature Requests) on SourceForge. Please join and write to
+aufs-users ML.
+
+
+6. Acknowledgements
+----------------------------------------
+Thanks to everyone who have tried and are using aufs, whoever
+have reported a bug or any feedback.
+
+Especially donors:
+Tomas Matejicek(slax.org) made a donation (much more than once).
+Dai Itasaka made a donation (2007/8).
+Chuck Smith made a donation (2008/4, 10 and 12).
+Henk Schoneveld made a donation (2008/9).
+Chih-Wei Huang, ASUS, CTC donated Eee PC 4G (2008/10).
+Francois Dupoux made a donation (2008/11).
+Bruno Cesar Ribas and Luis Carlos Erpen de Bona, C3SL serves public GIT
+tree (2009/2).
+William Grant made a donation (2009/3).
+
+Thank you very much.
+Donations are always, including future donations, very important and
+helpful for me to keep on developing aufs.
+
+
+7.
+----------------------------------------
+If you are an experienced user, no explanation is needed. Aufs is
+just a linux filesystem.
+
+
+Enjoy!
+
+# Local variables: ;
+# mode: text;
+# End: ;
diff --git a/Documentation/filesystems/aufs/aufs.5 b/Documentation/filesystems/aufs/aufs.5
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+.ds AUFS_VERSION aufs2
+.ds AUFS_XINO_FNAME .aufs.xino
+.ds AUFS_XINO_DEFPATH /tmp/.aufs.xino
+.ds AUFS_DIRWH_DEF 3
+.ds AUFS_WH_PFX .wh.
+.ds AUFS_WH_PFX_LEN 4
+.ds AUFS_WKQ_NAME aufsd
+.ds AUFS_NWKQ_DEF 4
+.ds AUFS_WH_DIROPQ .wh..wh..opq
+.ds AUFS_WH_BASE .wh..wh.aufs
+.ds AUFS_WH_PLINKDIR .wh..wh.plnk
+.ds AUFS_BRANCH_MAX 127
+.ds AUFS_MFS_SECOND_DEF 30
+.ds AUFS_RDBLK_DEF 512
+.ds AUFS_RDHASH_DEF 32
+.\".so aufs.tmac
+.
+.eo
+.de TQ
+.br
+.ns
+.TP \$1
+..
+.de Bu
+.IP \(bu 4
+..
+.ec
+.\" end of macro definitions
+.
+.\" ----------------------------------------------------------------------
+.TH aufs 5 \*[AUFS_VERSION] Linux "Linux Aufs User\[aq]s Manual"
+.SH NAME
+aufs \- advanced multi layered unification filesystem. version \*[AUFS_VERSION]
+
+.\" ----------------------------------------------------------------------
+.SH DESCRIPTION
+Aufs is a stackable unification filesystem such as Unionfs, which unifies
+several directories and provides a merged single directory.
+In the early days, aufs was entirely re-designed and re-implemented
+Unionfs Version 1.x series. After
+many original ideas, approaches and improvements, it
+becomes totally different from Unionfs while keeping the basic features.
+See Unionfs Version 1.x series for the basic features.
+Recently, Unionfs Version 2.x series begin taking some of same
+approaches to aufs\[aq]s.
+
+.\" ----------------------------------------------------------------------
+.SH MOUNT OPTIONS
+At mount-time, the order of interpreting options is,
+.RS
+.Bu
+simple flags, except xino/noxino and udba=inotify
+.Bu
+branches
+.Bu
+xino/noxino
+.Bu
+udba=inotify
+.RE
+
+At remount-time,
+the options are interpreted in the given order,
+e.g. left to right.
+.RS
+.Bu
+create or remove
+whiteout-base(\*[AUFS_WH_BASE]) and
+whplink-dir(\*[AUFS_WH_PLINKDIR]) if necessary
+.RE
+.
+.TP
+.B br:BRANCH[:BRANCH ...] (dirs=BRANCH[:BRANCH ...])
+Adds new branches.
+(cf. Branch Syntax).
+
+Aufs rejects the branch which is an ancestor or a descendant of another
+branch. It is called overlapped. When the branch is loopback-mounted
+directory, aufs also checks the source fs-image file of loopback
+device. If the source file is a descendant of another branch, it will
+be rejected too.
+
+After mounting aufs or adding a branch, if you move a branch under
+another branch and make it descendant of another branch, aufs will not
+work correctly.
+.
+.TP
+.B [ add | ins ]:index:BRANCH
+Adds a new branch.
+The index begins with 0.
+Aufs creates
+whiteout-base(\*[AUFS_WH_BASE]) and
+whplink-dir(\*[AUFS_WH_PLINKDIR]) if necessary.
+
+If there is the same named file on the lower branch (larger index),
+aufs will hide the lower file.
+You can only see the highest file.
+You will be confused if the added branch has whiteouts (including
+diropq), they may or may not hide the lower entries.
+.\" It is recommended to make sure that the added branch has no whiteout.
+
+Even if a process have once mapped a file by mmap(2) with MAP_SHARED
+and the same named file exists on the lower branch,
+the process still refers the file on the lower(hidden)
+branch after adding the branch.
+If you want to update the contents of a process address space after
+adding, you need to restart your process or open/mmap the file again.
+.\" Usually, such files are executables or shared libraries.
+(cf. Branch Syntax).
+.
+.TP
+.B del:dir
+Removes a branch.
+Aufs does not remove
+whiteout-base(\*[AUFS_WH_BASE]) and
+whplink-dir(\*[AUFS_WH_PLINKDIR]) automatically.
+For example, when you add a RO branch which was unified as RW, you
+will see whiteout-base or whplink-dir on the added RO branch.
+
+If a process is referencing the file/directory on the deleting branch
+(by open, mmap, current working directory, etc.), aufs will return an
+error EBUSY.
+.
+.TP
+.B mod:BRANCH
+Modifies the permission flags of the branch.
+Aufs creates or removes
+whiteout-base(\*[AUFS_WH_BASE]) and/or
+whplink-dir(\*[AUFS_WH_PLINKDIR]) if necessary.
+
+If the branch permission is been changing \[oq]rw\[cq] to \[oq]ro\[cq], and a process
+is mapping a file by mmap(2)
+.\" with MAP_SHARED
+on the branch, the process may or may not
+be able to modify its mapped memory region after modifying branch
+permission flags.
+(cf. Branch Syntax).
+.
+.TP
+.B append:BRANCH
+equivalent to \[oq]add:(last index + 1):BRANCH\[cq].
+(cf. Branch Syntax).
+.
+.TP
+.B prepend:BRANCH
+equivalent to \[oq]add:0:BRANCH.\[cq]
+(cf. Branch Syntax).
+.
+.TP
+.B xino=filename
+Use external inode number bitmap and translation table.
+When CONFIG_AUFS_EXPORT is enabled, external inode generation table too.
+It is set to
+<FirstWritableBranch>/\*[AUFS_XINO_FNAME] by default, or
+\*[AUFS_XINO_DEFPATH].
+Comma character in filename is not allowed.
+
+The files are created per an aufs and per a branch filesystem, and
+unlinked. So you
+cannot find this file, but it exists and is read/written frequently by
+aufs.
+(cf. External Inode Number Bitmap, Translation Table and Generation Table).
+
+If you enable CONFIG_SYSFS, the path of xino files are not shown in
+/proc/mounts (and /etc/mtab), instead it is shown in
+<sysfs>/fs/aufs/si_<id>/xi_path.
+Otherwise, it is shown in /proc/mounts unless it is not the default
+path.
+.
+.TP
+.B noxino
+Stop using external inode number bitmap and translation table.
+
+If you use this option,
+Some applications will not work correctly.
+.\" And pseudo link feature will not work after the inode cache is
+.\" shrunk.
+(cf. External Inode Number Bitmap, Translation Table and Generation Table).
+.
+.TP
+.B trunc_xib
+Truncate the external inode number bitmap file. The truncation is done
+automatically when you delete a branch unless you do not specify
+\[oq]notrunc_xib\[cq] option.
+(cf. External Inode Number Bitmap, Translation Table and Generation Table).
+.
+.TP
+.B notrunc_xib
+Stop truncating the external inode number bitmap file when you delete
+a branch.
+(cf. External Inode Number Bitmap, Translation Table and Generation Table).
+.
+.TP
+.B create_policy | create=CREATE_POLICY
+.TQ
+.B copyup_policy | copyup | cpup=COPYUP_POLICY
+Policies to select one among multiple writable branches. The default
+values are \[oq]create=tdp\[cq] and \[oq]cpup=tdp\[cq].
+link(2) and rename(2) systemcalls have an exception. In aufs, they
+try keeping their operations in the branch where the source exists.
+(cf. Policies to Select One among Multiple Writable Branches).
+.
+.TP
+.B verbose | v
+Print some information.
+Currently, it is only busy file (or inode) at deleting a branch.
+.
+.TP
+.B noverbose | quiet | q | silent
+Disable \[oq]verbose\[cq] option.
+This is default value.
+.
+.TP
+.B sum
+df(1)/statfs(2) returns the total number of blocks and inodes of
+all branches.
+Note that there are cases that systemcalls may return ENOSPC, even if
+df(1)/statfs(2) shows that aufs has some free space/inode.
+.
+.TP
+.B nosum
+Disable \[oq]sum\[cq] option.
+This is default value.
+.
+.TP
+.B dirwh=N
+Watermark to remove a dir actually at rmdir(2) and rename(2).
+
+If the target dir which is being removed or renamed (destination dir)
+has a huge number of whiteouts, i.e. the dir is empty logically but
+physically, the cost to remove/rename the single
+dir may be very high.
+It is
+required to unlink all of whiteouts internally before issuing
+rmdir/rename to the branch.
+To reduce the cost of single systemcall,
+aufs renames the target dir to a whiteout-ed temporary name and
+invokes a pre-created
+kernel thread to remove whiteout-ed children and the target dir.
+The rmdir/rename systemcall returns just after kicking the thread.
+
+When the number of whiteout-ed children is less than the value of
+dirwh, aufs remove them in a single systemcall instead of passing
+another thread.
+This value is ignored when the branch is NFS.
+The default value is \*[AUFS_DIRWH_DEF].
+.\" .
+.\" .TP
+.\" .B rdcache=N
+.
+.TP
+.B rdblk=N
+Specifies a size of internal VDIR block which is allocated at a time in
+byte.
+The VDIR block will be allocated several times when necessary. If your
+directory has millions of files, you may want to expand this size.
+The default value is defined as \*[AUFS_RDBLK_DEF].
+The size has to be lager than NAME_MAX (usually 255) and kmalloc\-able
+(the maximum limit depends on your system. at least 128KB is available
+for every system).
+(cf. Virtual or Vertical Directory Block).
+.
+.TP
+.B rdhash=N
+Specifies a size of internal VDIR hash table which is used to compare
+the file names under the same named directory on multiple branches.
+The VDIR hash table will be allocated in readdir(3)/getdents(2),
+rmdir(2) and rename(2) for the existing target directory. If your
+directory has millions of files, you may want to expand this size.
+The default value is defined as \*[AUFS_RDHASH_DEF].
+The size has to be lager than zero, and it will be multiplied by 4 or 8
+(for 32\-bit and 64\-bit respectively, currently). The result must be
+kmalloc\-able
+(the maximum limit depends on your system. at least 128KB is available
+for every system).
+(cf. Virtual or Vertical Directory Block).
+.
+.TP
+.B plink
+.TQ
+.B noplink
+Specifies to use \[oq]pseudo link\[cq] feature or not.
+The default is \[oq]plink\[cq] which means use this feature.
+(cf. Pseudo Link)
+.
+.TP
+.B clean_plink
+Removes all pseudo-links in memory.
+In order to make pseudo-link permanent, use
+\[oq]auplink\[cq] utility just before one of these operations,
+unmounting aufs,
+using \[oq]ro\[cq] or \[oq]noplink\[cq] mount option,
+deleting a branch from aufs,
+adding a branch into aufs,
+or changing your writable branch as readonly.
+If you installed both of /sbin/mount.aufs and /sbin/umount.aufs, and your
+mount(8) and umount(8) support them,
+\[oq]auplink\[cq] utility will be executed automatically and flush pseudo-links.
+(cf. Pseudo Link)
+.
+.TP
+.B udba=none | reval | inotify
+Specifies the level of UDBA (User\[aq]s Direct Branch Access) test.
+(cf. User\[aq]s Direct Branch Access and Inotify Limitation).
+.
+.TP
+.B diropq=whiteouted | w | always | a
+Specifies whether mkdir(2) and rename(2) dir case make the created directory
+\[oq]opaque\[cq] or not.
+In other words, to create \[oq]\*[AUFS_WH_DIROPQ]\[cq] under the created or renamed
+directory, or not to create.
+When you specify diropq=w or diropq=whiteouted, aufs will not create
+it if the
+directory was not whiteouted or opaqued. If the directory was whiteouted
+or opaqued, the created or renamed directory will be opaque.
+When you specify diropq=a or diropq==always, aufs will always create
+it regardless
+the directory was whiteouted/opaqued or not.
+The default value is diropq=w, it means not to create when it is unnecessary.
+If you define CONFIG_AUFS_COMPAT at aufs compiling time, the default will be
+diropq=a.
+You need to consider this option if you are planning to add a branch later
+since \[oq]diropq\[cq] affects the same named directory on the added branch.
+.
+.TP
+.B warn_perm
+.TQ
+.B nowarn_perm
+Adding a branch, aufs will issue a warning about uid/gid/permission of
+the adding branch directory,
+when they differ from the existing branch\[aq]s. This difference may or
+may not impose a security risk.
+If you are sure that there is no problem and want to stop the warning,
+use \[oq]nowarn_perm\[cq] option.
+The default is \[oq]warn_perm\[cq] (cf. DIAGNOSTICS).
+
+.\" ----------------------------------------------------------------------
+.SH Module Parameters
+.TP
+.B nwkq=N
+The number of kernel thread named \*[AUFS_WKQ_NAME].
+
+Those threads stay in the system while the aufs module is loaded,
+and handle the special I/O requests from aufs.
+The default value is \*[AUFS_NWKQ_DEF].
+
+The special I/O requests from aufs include a part of copy-up, lookup,
+directory handling, pseudo-link, xino file operations and the
+delegated access to branches.
+For example, Unix filesystems allow you to rmdir(2) which has no write
+permission bit, if its parent directory has write permission bit. In aufs, the
+removing directory may or may not have whiteout or \[oq]dir opaque\[cq] mark as its
+child. And aufs needs to unlink(2) them before rmdir(2).
+Therefore aufs delegates the actual unlink(2) and rmdir(2) to another kernel
+thread which has been created already and has a superuser privilege.
+
+If you enable CONFIG_SYSFS, you can check this value through
+<sysfs>/module/aufs/parameters/nwkq.
+
+.
+.TP
+.B brs=1 | 0
+Specifies to use the branch path data file under sysfs or not.
+
+If the number of your branches is large or their path is long
+and you meet the limitation of mount(8) ro /etc/mtab, you need to
+enable CONFIG_SYSFS and set aufs module parameter brs=1.
+
+When this parameter is set as 1, aufs does not show \[oq]br:\[cq] (or dirs=)
+mount option through /proc/mounts (and /etc/mtab). So you can
+keep yourself from the page limitation of
+mount(8) or /etc/mtab.
+Aufs shows branch paths through <sysfs>/fs/aufs/si_XXX/brNNN.
+Actually the file under sysfs has also a size limitation, but I don\[aq]t
+think it is harmful.
+
+There is one more side effect in setting 1 to this parameter.
+If you rename your branch, the branch path written in /etc/mtab will be
+obsoleted and the future remount will meet some error due to the
+unmatched parameters (Remember that mount(8) may take the options from
+/etc/mtab and pass them to the systemcall).
+If you set 1, /etc/mtab will not hold the branch path and you will not
+meet such trouble. On the other hand, the entires for the
+branch path under sysfs are generated dynamically. So it must not be obsoleted.
+But I don\[aq]t think users want to rename branches so often.
+
+If CONFIG_SYSFS is disable, this paramater is always set to 0.
+.
+.TP
+.B sysrq=key
+Specifies MagicSysRq key for debugging aufs.
+You need to enable both of CONFIG_MAGIC_SYSRQ and CONFIG_AUFS_DEBUG.
+Currently this is for developers only.
+The default is \[oq]a\[cq].
+.
+.TP
+.B debug= 0 | 1
+Specifies disable(0) or enable(1) debug print in aufs.
+This parameter can be changed dynamically.
+You need to enable CONFIG_AUFS_DEBUG.
+Currently this is for developers only.
+The default is \[oq]0\[cq] (disable).
+
+.\" ----------------------------------------------------------------------
+.SH Entries under Sysfs and Debugfs
+See linux/Documentation/ABI/*/{sys,debug}fs-aufs.
+
+.\" ----------------------------------------------------------------------
+.SH Branch Syntax
+.TP
+.B dir_path[ =permission [ + attribute ] ]
+.TQ
+.B permission := rw | ro | rr
+.TQ
+.B attribute := wh | nolwh
+dir_path is a directory path.
+The keyword after \[oq]dir_path=\[cq] is a
+permission flags for that branch.
+Comma, colon and the permission flags string (including \[oq]=\[cq])in the path
+are not allowed.
+
+Any filesystem can be a branch, But some are not accepted such like
+sysfs, procfs and unionfs.
+If you specify such filesystems as an aufs branch, aufs will return an error
+saying it is unsupported.
+
+Cramfs in linux stable release has strange inodes and it makes aufs
+confused. For example,
+.nf
+$ mkdir -p w/d1 w/d2
+$ > w/z1
+$ > w/z2
+$ mkcramfs w cramfs
+$ sudo mount -t cramfs -o ro,loop cramfs /mnt
+$ find /mnt -ls
+    76    1 drwxr-xr-x   1 jro      232            64 Jan  1  1970 /mnt
+     1    1 drwxr-xr-x   1 jro      232             0 Jan  1  1970 /mnt/d1
+     1    1 drwxr-xr-x   1 jro      232             0 Jan  1  1970 /mnt/d2
+     1    1 -rw-r--r--   1 jro      232             0 Jan  1  1970 /mnt/z1
+     1    1 -rw-r--r--   1 jro      232             0 Jan  1  1970 /mnt/z2
+.fi
+
+All these two directories and two files have the same inode with one
+as their link count. Aufs cannot handle such inode correctly.
+Currently, aufs involves a tiny workaround for such inodes. But some
+applications may not work correctly since aufs inode number for such
+inode will change silently.
+If you do not have any empty files, empty directories or special files,
+inodes on cramfs will be all fine.
+
+A branch should not be shared as the writable branch between multiple
+aufs. A readonly branch can be shared.
+
+The maximum number of branches is configurable at compile time.
+The current value is \*[AUFS_BRANCH_MAX] which depends upon
+configuration.
+
+When an unknown permission or attribute is given, aufs sets ro to that
+branch silently.
+
+.SS Permission
+.
+.TP
+.B rw
+Readable and writable branch. Set as default for the first branch.
+If the branch filesystem is mounted as readonly, you cannot set it \[oq]rw.\[cq]
+.\" A filesystem which does not support link(2) and i_op\->setattr(), for
+.\" example FAT, will not be used as the writable branch.
+.
+.TP
+.B ro
+Readonly branch and it has no whiteouts on it.
+Set as default for all branches except the first one. Aufs never issue
+both of write operation and lookup operation for whiteout to this branch.
+.
+.TP
+.B rr
+Real readonly branch, special case of \[oq]ro\[cq], for natively readonly
+branch. Assuming the branch is natively readonly, aufs can optimize
+some internal operation. For example, if you specify \[oq]udba=inotify\[cq]
+option, aufs does not set inotify for the things on rr branch.
+Set by default for a branch whose fs-type is either \[oq]iso9660\[cq],
+\[oq]cramfs\[cq] or \[oq]romfs\[cq].
+
+When your branch exists on slower device and you have some
+capacity on your hdd, you may want to try ulobdev tool in ULOOP sample.
+It can cache the contents of the real devices on another faster device,
+so you will be able to get the better access performance.
+The ulobdev tool is for a generic block device, and the ulohttp is for a
+filesystem image on http server.
+If you want to spin down your hdd to save the
+battery life or something, then you may want to use ulobdev to save the
+access to the hdd, too.
+See $AufsCVS/sample/uloop in detail.
+
+.SS Attribute
+.
+.TP
+.B wh
+Readonly branch and it has/might have whiteouts on it.
+Aufs never issue write operation to this branch, but lookup for whiteout.
+Use this as \[oq]<branch_dir>=ro+wh\[cq].
+.
+.TP
+.B nolwh
+Usually, aufs creates a whiteout as a hardlink on a writable
+branch. This attributes prohibits aufs to create the hardlinked
+whiteout, including the source file of all hardlinked whiteout
+(\*[AUFS_WH_BASE].)
+If you do not like a hardlink, or your writable branch does not support
+link(2), then use this attribute.
+But I am afraid a filesystem which does not support link(2) natively
+will fail in other place such as copy-up.
+Use this as \[oq]<branch_dir>=rw+nolwh\[cq].
+Also you may want to try \[oq]noplink\[cq] mount option, while it is not recommended.
+
+.\" .SS FUSE as a branch
+.\" A FUSE branch needs special attention.
+.\" The struct fuse_operations has a statfs operation. It is OK, but the
+.\" parameter is struct statvfs* instead of struct statfs*. So almost
+.\" all user\-space implementaion will call statvfs(3)/fstatvfs(3) instead of
+.\" statfs(2)/fstatfs(2).
+.\" In glibc, [f]statvfs(3) issues [f]statfs(2), open(2)/read(2) for
+.\" /proc/mounts,
+.\" and stat(2) for the mountpoint. With this situation, a FUSE branch will
+.\" cause a deadlock in creating something in aufs. Here is a sample
+.\" scenario,
+.\" .\" .RS
+.\" .\" .IN -10
+.\" .Bu
+.\" create/modify a file just under the aufs root dir.
+.\" .Bu
+.\" aufs aquires a write\-lock for the parent directory, ie. the root dir.
+.\" .Bu
+.\" A library function or fuse internal may call statfs for a fuse branch.
+.\" The create=mfs mode in aufs will surely call statfs for each writable
+.\" branches.
+.\" .Bu
+.\" FUSE in kernel\-space converts and redirects the statfs request to the
+.\" user\-space.
+.\" .Bu
+.\" the user\-space statfs handler will call [f]statvfs(3).
+.\" .Bu
+.\" the [f]statvfs(3) in glibc will access /proc/mounts and issue
+.\" stat(2) for the mountpoint. But those require a read\-lock for the aufs
+.\" root directory.
+.\" .Bu
+.\" Then a deadlock occurs.
+.\" .\" .RE 1
+.\" .\" .IN
+.\" 
+.\" In order to avoid this deadlock, I would suggest not to call
+.\" [f]statvfs(3) from fuse. Here is a sample code to do this.
+.\" .nf
+.\" struct statvfs stvfs;
+.\" 
+.\" main()
+.\" {
+.\"    statvfs(..., &stvfs)
+.\"    or
+.\"    fstatvfs(..., &stvfs)
+.\"    stvfs.f_fsid = 0
+.\" }
+.\" 
+.\" statfs_handler(const char *path, struct statvfs *arg)
+.\" {
+.\"    struct statfs stfs
+.\" 
+.\"    memcpy(arg, &stvfs, sizeof(stvfs))
+.\" 
+.\"    statfs(..., &stfs)
+.\"    or
+.\"    fstatfs(..., &stfs)
+.\" 
+.\"    arg->f_bfree = stfs.f_bfree
+.\"    arg->f_bavail = stfs.f_bavail
+.\"    arg->f_ffree = stfs.f_ffree
+.\"    arg->f_favail = /* any value */
+.\" }
+.\" .fi
+
+.\" ----------------------------------------------------------------------
+.SH External Inode Number Bitmap, Translation Table and Generation Table (xino)
+Aufs uses one external bitmap file and one external inode number
+translation table files per an aufs and per a branch
+filesystem by default.
+Additionally when CONFIG_AUFS_EXPORT is enabled, one external inode
+generation table is added.
+The bitmap (and the generation table) is for recycling aufs inode number
+and the others
+are a table for converting an inode number on a branch to
+an aufs inode number. The default path
+is \[oq]first writable branch\[cq]/\*[AUFS_XINO_FNAME].
+If there is no writable branch, the
+default path
+will be \*[AUFS_XINO_DEFPATH].
+.\" A user who executes mount(8) needs the privilege to create xino
+.\" file.
+
+If you enable CONFIG_SYSFS, the path of xino files are not shown in
+/proc/mounts (and /etc/mtab), instead it is shown in
+<sysfs>/fs/aufs/si_<id>/xi_path.
+Otherwise, it is shown in /proc/mounts unless it is not the default
+path.
+
+Those files are always opened and read/write by aufs frequently.
+If your writable branch is on flash memory device, it is recommended
+to put xino files on other than flash memory by specifying \[oq]xino=\[cq]
+mount option.
+
+The
+maximum file size of the bitmap is, basically, the amount of the
+number of all the files on all branches divided by 8 (the number of
+bits in a byte).
+For example, on a 4KB page size system, if you have 32,768 (or
+2,599,968) files in aufs world,
+then the maximum file size of the bitmap is 4KB (or 320KB).
+
+The
+maximum file size of the table will
+be \[oq]max inode number on the branch x size of an inode number\[cq].
+For example in 32bit environment,
+
+.nf
+$ df -i /branch_fs
+/dev/hda14           2599968  203127 2396841    8% /branch_fs
+.fi
+
+and /branch_fs is an branch of the aufs. When the inode number is
+assigned contiguously (without \[oq]hole\[cq]), the maximum xino file size for
+/branch_fs will be 2,599,968 x 4 bytes = about 10 MB. But it might not be
+allocated all of disk blocks.
+When the inode number is assigned discontinuously, the maximum size of
+xino file will be the largest inode number on a branch x 4 bytes.
+Additionally, the file size is limited to LLONG_MAX or the s_maxbytes
+in filesystem\[aq]s superblock (s_maxbytes may be smaller than
+LLONG_MAX). So the
+support-able largest inode number on a branch is less than
+2305843009213693950 (LLONG_MAX/4\-1).
+This is the current limitation of aufs.
+On 64bit environment, this limitation becomes more strict and the
+supported largest inode number is less than LLONG_MAX/8\-1.
+
+The xino files are always hidden, i.e. removed. So you cannot
+do \[oq]ls \-l xino_file\[cq].
+If you enable CONFIG_DEBUG_FS, you can check these information through
+<debugfs>/aufs/<si_id>/{xib,xi[0-9]*,xigen}. xib is for the bitmap file,
+xi0 ix for the first branch, and xi1 is for the next. xigen is for the
+generation table.
+xib and xigen are in the format of,
+
+.nf
+<blocks>x<block size> <file size>
+.fi
+
+Note that a filesystem usually has a
+feature called pre-allocation, which means a number of
+blocks are allocated automatically, and then deallocated
+silently when the filesystem thinks they are unnecessary.
+You do not have to be surprised the sudden changes of the number of
+blocks, when your filesystem which xino files are placed supports the
+pre-allocation feature.
+
+The rests are hidden xino file information in the format of,
+
+.nf
+<file count>, <blocks>x<block size> <file size>
+.fi
+
+If the file count is larger than 1, it means some of your branches are
+on the same filesystem and the xino file is shared by them.
+Note that the file size may not be equal to the actual consuming blocks
+since xino file is a sparse file, i.e. a hole in a file which does not
+consume any disk blocks.
+
+Once you unmount aufs, the xino files for that aufs are totally gone.
+It means that the inode number is not permanent across umount or
+shutdown.
+
+The xino files should be created on the filesystem except NFS.
+If your first writable branch is NFS, you will need to specify xino
+file path other than NFS.
+Also if you are going to remove the branch where xino files exist or
+change the branch permission to readonly, you need to use xino option
+before del/mod the branch.
+
+The bitmap file can be truncated.
+For example, if you delete a branch which has huge number of files,
+many inode numbers will be recycled and the bitmap will be truncated
+to smaller size. Aufs does this automatically when a branch is
+deleted.
+You can truncate it anytime you like if you specify \[oq]trunc_xib\[cq] mount
+option. But when the accessed inode number was not deleted, nothing
+will be truncated.
+If you do not want to truncate it (it may be slow) when you delete a
+branch, specify \[oq]notrunc_xib\[cq] after \[oq]del\[cq] mount option.
+
+If you do not want to use xino, use noxino mount option. Use this
+option with care, since the inode number may be changed silently and
+unexpectedly anytime.
+For example,
+rmdir failure, recursive chmod/chown/etc to a large and deep directory
+or anything else.
+And some applications will not work correctly.
+.\" When the inode number has been changed, your system
+.\" can be crazy.
+If you want to change the xino default path, use xino mount option.
+
+After you add branches, the persistence of inode number may not be
+guaranteed.
+At remount time, cached but unused inodes are discarded.
+And the newly appeared inode may have different inode number at the
+next access time. The inodes in use have the persistent inode number.
+
+When aufs assigned an inode number to a file, and if you create the
+same named file on the upper branch directly, then the next time you
+access the file, aufs may assign another inode number to the file even
+if you use xino option.
+Some applications may treat the file whose inode number has been
+changed as totally different file.
+
+.\" ----------------------------------------------------------------------
+.SH Pseudo Link (hardlink over branches)
+Aufs supports \[oq]pseudo link\[cq] which is a logical hard-link over
+branches (cf. ln(1) and link(2)).
+In other words, a copied-up file by link(2) and a copied-up file which was
+hard-linked on a readonly branch filesystem.
+
+When you have files named fileA and fileB which are
+hardlinked on a readonly branch, if you write something into fileA,
+aufs copies-up fileA to a writable branch, and write(2) the originally
+requested thing to the copied-up fileA. On the writable branch,
+fileA is not hardlinked.
+But aufs remembers it was hardlinked, and handles fileB as if it existed
+on the writable branch, by referencing  fileA\[aq]s inode on the writable
+branch as fileB\[aq]s inode.
+
+Once you unmount aufs, the plink info for that aufs kept in memory are totally
+gone.
+It means that the pseudo-link is not permanent.
+If you want to make plink permanent, try \[oq]auplink\[cq] utility just before
+one of these operations,
+unmounting your aufs,
+using \[oq]ro\[cq] or \[oq]noplink\[cq] mount option,
+deleting a branch from aufs,
+adding a branch into aufs,
+or changing your writable branch to readonly.
+
+This utility will reproduces all real hardlinks on a writable branch by linking
+them, and removes pseudo-link info in memory and temporary link on the
+writable branch.
+Since this utility access your branches directly, you cannot hide them by
+\[oq]mount \-\-bind /tmp /branch\[cq] or something.
+
+If you are willing to rebuild your aufs with the same branches later, you
+should use auplink utility before you umount your aufs.
+If you installed both of /sbin/mount.aufs and /sbin/umount.aufs, and your
+mount(8) and umount(8) support them,
+\[oq]auplink\[cq] utility will be executed automatically and flush pseudo-links.
+
+.nf
+# auplink /your/aufs/root flush
+# umount /your/aufs/root
+or
+# auplink /your/aufs/root flush
+# mount -o remount,mod:/your/writable/branch=ro /your/aufs/root
+or
+# auplink /your/aufs/root flush
+# mount -o remount,noplink /your/aufs/root
+or
+# auplink /your/aufs/root flush
+# mount -o remount,del:/your/aufs/branch /your/aufs/root
+or
+# auplink /your/aufs/root flush
+# mount -o remount,append:/your/aufs/branch /your/aufs/root
+.fi
+
+The plinks are kept both in memory and on disk. When they consumes too much
+resources on your system, you can use the \[oq]auplink\[cq] utility at anytime and
+throw away the unnecessary pseudo-links in safe.
+
+Additionally, the \[oq]auplink\[cq] utility is very useful for some security reasons.
+For example, when you have a directory whose permission flags
+are 0700, and a file who is 0644 under the 0700 directory. Usually,
+all files under the 0700 directory are private and no one else can see
+the file. But when the directory is 0711 and someone else knows the 0644
+filename, he can read the file.
+
+Basically, aufs pseudo-link feature creates a temporary link under the
+directory whose owner is root and the permission flags are 0700.
+But when the writable branch is NFS, aufs sets 0711 to the directory.
+When the 0644 file is pseudo-linked, the temporary link, of course the
+contents of the file is totally equivalent, will be created under the
+0711 directory. The filename will be generated by its inode number.
+While it is hard to know the generated filename, someone else may try peeping
+the temporary pseudo-linked file by his software tool which may try the name
+from one to MAX_INT or something.
+In this case, the 0644 file will be read unexpectedly.
+I am afraid that leaving the temporary pseudo-links can be a security hole.
+It makes sense to execute \[oq]auplink /your/aufs/root flush\[cq]
+periodically, when your writable branch is NFS.
+
+When your writable branch is not NFS, or all users are careful enough to set 0600
+to their private files, you do not have to worry about this issue.
+
+If you do not want this feature, use \[oq]noplink\[cq] mount option.
+
+.SS The behaviours of plink and noplink
+This sample shows that the \[oq]f_src_linked2\[cq] with \[oq]noplink\[cq] option cannot follow
+the link.
+
+.nf
+none on /dev/shm/u type aufs (rw,xino=/dev/shm/rw/.aufs.xino,br:/dev/shm/rw=rw:/dev/shm/ro=ro)
+$ ls -li ../r?/f_src_linked* ./f_src_linked* ./copied
+ls: ./copied: No such file or directory
+15 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked
+15 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked2
+22 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ./f_src_linked
+22 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ./f_src_linked2
+$ echo abc >> f_src_linked
+$ cp f_src_linked copied
+$ ls -li ../r?/f_src_linked* ./f_src_linked* ./copied
+15 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked
+15 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked2
+36 -rw-r--r--  2 jro jro 6 Dec 22 11:03 ../rw/f_src_linked
+53 -rw-r--r--  1 jro jro 6 Dec 22 11:03 ./copied
+22 -rw-r--r--  2 jro jro 6 Dec 22 11:03 ./f_src_linked
+22 -rw-r--r--  2 jro jro 6 Dec 22 11:03 ./f_src_linked2
+$ cmp copied f_src_linked2
+$
+
+none on /dev/shm/u type aufs (rw,xino=/dev/shm/rw/.aufs.xino,noplink,br:/dev/shm/rw=rw:/dev/shm/ro=ro)
+$ ls -li ../r?/f_src_linked* ./f_src_linked* ./copied
+ls: ./copied: No such file or directory
+17 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked
+17 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked2
+23 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ./f_src_linked
+23 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ./f_src_linked2
+$ echo abc >> f_src_linked
+$ cp f_src_linked copied
+$ ls -li ../r?/f_src_linked* ./f_src_linked* ./copied
+17 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked
+17 -rw-r--r--  2 jro jro 2 Dec 22 11:03 ../ro/f_src_linked2
+36 -rw-r--r--  1 jro jro 6 Dec 22 11:03 ../rw/f_src_linked
+53 -rw-r--r--  1 jro jro 6 Dec 22 11:03 ./copied
+23 -rw-r--r--  2 jro jro 6 Dec 22 11:03 ./f_src_linked
+23 -rw-r--r--  2 jro jro 6 Dec 22 11:03 ./f_src_linked2
+$ cmp copied f_src_linked2
+cmp: EOF on f_src_linked2
+$
+.fi
+
+.\"
+.\" If you add/del a branch, or link/unlink the pseudo-linked
+.\" file on a branch
+.\" directly, aufs cannot keep the correct link count, but the status of
+.\" \[oq]pseudo-linked.\[cq]
+.\" Those files may or may not keep the file data after you unlink the
+.\" file on the branch directly, especially the case of your branch is
+.\" NFS.
+
+If you add a branch which has fileA or fileB, aufs does not follow the
+pseudo link. The file on the added branch has no relation to the same
+named file(s) on the lower branch(es).
+If you use noxino mount option, pseudo link will not work after the
+kernel shrinks the inode cache.
+
+This feature will not work for squashfs before version 3.2 since its
+inode is tricky.
+When the inode is hardlinked, squashfs inodes has the same inode
+number and correct link count, but the inode memory object is
+different. Squashfs inodes (before v3.2) are generated for each, even
+they are hardlinked.
+
+.\" ----------------------------------------------------------------------
+.SH User\[aq]s Direct Branch Access (UDBA)
+UDBA means a modification to a branch filesystem manually or directly,
+e.g. bypassing aufs.
+While aufs is designed and implemented to be safe after UDBA,
+it can make yourself and your aufs confused. And some information like
+aufs inode will be incorrect.
+For example, if you rename a file on a branch directly, the file on
+aufs may
+or may not be accessible through both of old and new name.
+Because aufs caches various information about the files on
+branches. And the cache still remains after UDBA.
+
+Aufs has a mount option named \[oq]udba\[cq] which specifies the test level at
+access time whether UDBA was happened or not.
+.
+.TP
+.B udba=none
+Aufs trusts the dentry and the inode cache on the system, and never
+test about UDBA. With this option, aufs runs fastest, but it may show
+you incorrect data.
+Additionally, if you often modify a branch
+directly, aufs will not be able to trace the changes of inodes on the
+branch. It can be a cause of wrong behaviour, deadlock or anything else.
+
+It is recommended to use this option only when you are sure that
+nobody access a file on a branch.
+It might be difficult for you to achieve real \[oq]no UDBA\[cq] world when you
+cannot stop your users doing \[oq]find / \-ls\[cq] or something.
+If you really want to forbid all of your users to UDBA, here is a trick
+for it.
+With this trick, users cannot see the
+branches directly and aufs runs with no problem, except \[oq]auplink\[cq] utility.
+But if you are not familiar with aufs, this trick may make
+yourself confused.
+
+.nf
+# d=/tmp/.aufs.hide
+# mkdir $d
+# for i in $branches_you_want_to_hide
+> do
+>      mount -n --bind $d $i
+> done
+.fi
+
+When you unmount the aufs, delete/modify the branch by remount, or you
+want to show the hidden branches again, unmount the bound
+/tmp/.aufs.hide.
+
+.nf
+# umount -n $branches_you_want_to_unbound
+.fi
+
+If you use FUSE filesystem as an aufs branch which supports hardlink,
+you should not set this option, since FUSE makes inode objects for
+each hardlinks (at least in linux\-2.6.23). When your FUSE filesystem
+maintains them at link/unlinking, it is equivalent
+to \[oq]direct branch access\[cq] for aufs.
+
+.
+.TP
+.B udba=reval
+Aufs tests only the existence of the file which existed. If
+the existed file was removed on the branch directly, aufs
+discard the cache about the file and
+re-lookup it. So the data will be updated.
+This test is at minimum level to keep the performance and ensure the
+existence of a file.
+This is default and aufs runs still fast.
+
+This rule leads to some unexpected situation, but I hope it is
+harmless. Those are totally depends upon cache. Here are just a few
+examples.
+.
+.RS
+.Bu
+If the file is cached as negative or
+not-existed, aufs does not test it. And the file is still handled as
+negative after a user created the file on a branch directly. If the
+file is not cached, aufs will lookup normally and find the file.
+.
+.Bu
+When the file is cached as positive or existed, and a user created the
+same named file directly on the upper branch. Aufs detects the cached
+inode of the file is still existing and will show you the old (cached)
+file which is on the lower branch.
+.
+.Bu
+When the file is cached as positive or existed, and a user renamed the
+file by rename(2) directly. Aufs detects the inode of the file is
+still existing. You may or may not see both of the old and new files.
+Todo: If aufs also tests the name, we can detect this case.
+.RE
+
+If your outer modification (UDBA) is rare and you can ignore the
+temporary and minor differences between virtual aufs world and real
+branch filesystem, then try this mount option.
+.
+.TP
+.B udba=inotify
+Aufs sets \[oq]inotify\[cq] to all the accessed directories on its branches
+and receives the event about the dir and its children. It consumes
+resources, cpu and memory. And I am afraid that the performance will be
+hurt, but it is most strict test level.
+There are some limitations of linux inotify, see also Inotify
+Limitation.
+So it is recommended to leave udba default option usually, and set it
+to inotify by remount when you need it.
+
+When a user accesses the file which was notified UDBA before, the cached data
+about the file will be discarded and aufs re-lookup it. So the data will
+be updated.
+When an error condition occurs between UDBA and aufs operation, aufs
+will return an error, including EIO.
+To use this option, you need to enable CONFIG_INOTIFY and
+CONFIG_AUFS_UDBA_INOTIFY.
+
+To rename/rmdir a directory on a branch directory may reveal the same named
+directory on the lower branch. Aufs tries re-lookuping the renamed
+directory and the revealed directory and assigning different inode
+number to them. But the inode number including their children can be a
+problem. The inode numbers will be changed silently, and
+aufs may produce a warning. If you rename a directory repeatedly and
+reveal/hide the lower directory, then aufs may confuse their inode
+numbers too. It depends upon the system cache.
+
+When you make a directory in aufs and mount other filesystem on it,
+the directory in aufs cannot be removed expectedly because it is a
+mount point. But the same named directory on the writable branch can
+be removed, if someone wants. It is just an empty directory, instead
+of a mount point.
+Aufs cannot stop such direct rmdir, but produces a warning about it.
+
+If the pseudo-linked file is hardlinked or unlinked on the branch
+directly, its inode link count in aufs may be incorrect. It is
+recommended to flush the psuedo-links by auplink script.
+
+.\" ----------------------------------------------------------------------
+.SH Linux Inotify Limitation
+Unfortunately, current inotify (linux\-2.6.18) has some limitations,
+and aufs must derive it.
+
+.SS IN_ATTRIB, updating atime
+When a file/dir on a branch is accessed directly, the inode atime (access
+time, cf. stat(2)) may or may not be updated. In some cases, inotify
+does not fire this event. So the aufs inode atime may remain old.
+
+.SS IN_ATTRIB, updating nlink
+When the link count of a file on a branch is incremented by link(2)
+directly,
+inotify fires IN_CREATE to the parent
+directory, but IN_ATTRIB to the file. So the aufs inode nlink may
+remain old.
+
+.SS IN_DELETE, removing file on NFS
+When a file on a NFS branch is deleted directly, inotify may or may
+not fire
+IN_DELETE event. It depends upon the status of dentry
+(DCACHE_NFSFS_RENAMED flag).
+In this case, the file on aufs seems still exists. Aufs and any user can see
+the file.
+
+.SS IN_IGNORED, deleted rename target
+When a file/dir on a branch is unlinked by rename(2) directly, inotify
+fires IN_IGNORED which means the inode is deleted. Actually, in some
+cases, the inode survives. For example, the rename target is linked or
+opened. In this case, inotify watch set by aufs is removed by VFS and
+inotify.
+And aufs cannot receive the events anymore. So aufs may show you
+incorrect data about the file/dir.
+
+.\" ----------------------------------------------------------------------
+.SH Virtual or Vertical Directory Block (VDIR)
+In order to provide the merged view of file listing, aufs builds
+internal direcotry block on memory. For readdir, aufs performs readdir()
+internally for each dir on branches, merges their entries with
+eliminating the whiteout\-ed ones, and sets it to the opened file (dir)
+object. So the file object has its entry list until it is closed. The
+entry list will be updated when the file position is zero (by
+rewinddir(3)) and becomes obsoleted.
+
+Some people may call it can be a security hole or invite DoS attack
+since the opened and once readdir\-ed dir (file object) holds its entry
+list and becomes a pressure for system memory. But I would say it is similar
+to files under /proc or /sys. The virtual files in them also holds a
+memory page (generally) while they are opened. When an idea to reduce
+memory for them is introduced, it will be applied to aufs too.
+
+The dynamically allocated memory block for the name of entries has a
+unit of \*[AUFS_RDBLK_DEF] bytes by default.
+During building dir blocks, aufs creates hash list (hashed and divied by
+\*[AUFS_RDHASH_DEF] by default) and judging whether
+the entry is whiteouted by its upper branch or already listed.
+
+These values are suitable for normal environments. But you may have
+millions of files or very long filenames under a single direcotry. For
+such cases, you may need to customize these values by spicifying rdblk=
+and rdhash= aufs mount options.
+
+For instance, there are 97 files under my /bin, and the total name
+length is 597 bytes.
+
+.nf
+$ \\ls -1 /bin | wc
+     97      97     597
+.fi
+
+Strictly speaking, 97 end\-of\-line codes are
+included. But it is OK since aufs VDIR also stores the name length in 1
+byte. In this case, you do not need to customize the default values. 597 bytes
+filenames will be stored in 2 VDIR memory blocks (597 <
+\*[AUFS_RDBLK_DEF] x 2).
+And 97 filenames are distributed among \*[AUFS_RDHASH_DEF] lists, so one
+list will point 4 names in average. To judge the names is whiteouted or
+not, the number of comparision will be 4. 2 memory allocations
+and 4 comparison costs low (even if the directory is opened for a long
+time). So you do not need to customize.
+
+If your directory has millions of files, the you will need to specify
+rdblk= and rdhash=.
+
+.nf
+$ ls -U /mnt/rotating-rust | wc -l
+1382438
+.fi
+
+In this case, assuming the average length of filenames is 6, in order to
+get better time performance I would
+recommend to set $((128*1024)) or $((64*1024)) for rdblk, and
+$((8*1024)) or $((4*1024)) for rdhash.
+You can change these values of the active aufs mount by "mount -o
+remount".
+
+This customization is not for
+reducing the memory space, but for reducing time for the number of memory
+allocation and the name comparison. The larger value is faster, in
+general. Of course, you will need system memory. This is a generic
+"time\-vs\-space" problem.
+
+.\" ----------------------------------------------------------------------
+.SH Copy On Write, or aufs internal copyup and copydown
+Every stackable filesystem which implements copy\-on\-write supports the
+copyup feature. The feature is to copy a file/dir from the lower branch
+to the upper internally. When you have one readonly branch and one
+upper writable branch, and you append a string to a file which exists on
+the readonly branch, then aufs will copy the file from the readonly
+branch to the writable branch with its directory hierarchy. It means one
+write(2) involves several logical/internal mkdir(2), creat(2), read(2),
+write(2) and close(2) systemcalls
+before the actual expected write(2) is performed. Sometimes it may take
+a long time, particulary when the file is very large.
+If CONFIG_AUFS_DEBUG is enabled, aufs produces a message saying \[oq]copying
+a large file.\[cq]
+
+You may see the message when you change the xino file path or
+truncate the xino/xib files. Sometimes those files can be large and may
+take a long time to handle them.
+
+.\" ----------------------------------------------------------------------
+.SH Policies to Select One among Multiple Writable Branches
+Aufs has some policies to select one among multiple writable branches
+when you are going to write/modify something. There are two kinds of
+policies, one is for newly create something and the other is for
+internal copy-up.
+You can select them by specifying mount option \[oq]create=CREATE_POLICY\[cq]
+or \[oq]cpup=COPYUP_POLICY.\[cq]
+These policies have no meaning when you have only one writable
+branch. If there is some meaning, it must hurt the performance.
+
+.SS Exceptions for Policies
+In every cases below, even if the policy says that the branch where a
+new file should be created is /rw2, the file will be created on /rw1.
+.
+.Bu
+If there is a readonly branch with \[oq]wh\[cq] attribute above the
+policy-selected branch and the parent dir is marked as opaque,
+or the target (creating) file is whiteouted on the ro+wh branch, then
+the policy will be ignored and the target file will be created on the
+nearest upper writable branch than the ro+wh branch.
+.RS
+.nf
+/aufs = /rw1 + /ro+wh/diropq + /rw2
+/aufs = /rw1 + /ro+wh/wh.tgt + /rw2
+.fi
+.RE
+.
+.Bu
+If there is a writable branch above the policy-selected branch and the
+parent dir is marked as opaque or the target file is whiteouted on the
+branch, then the policy will be ignored and the target file will be
+created on the highest one among the upper writable branches who has
+diropq or whiteout. In case of whiteout, aufs removes it as usual.
+.RS
+.nf
+/aufs = /rw1/diropq + /rw2
+/aufs = /rw1/wh.tgt + /rw2
+.fi
+.RE
+.
+.Bu
+link(2) and rename(2) systemcalls are exceptions in every policy.
+They try selecting the branch where the source exists as possible since
+copyup a large file will take long time. If it can\[aq]t be, ie. the
+branch where the source exists is readonly, then they will follow the
+copyup policy.
+.
+.Bu
+There is an exception for rename(2) when the target exists.
+If the rename target exists, aufs compares the index of the branches
+where the source and the target are existing and selects the higher
+one. If the selected branch is readonly, then aufs follows the copyup
+policy.
+
+.SS Policies for Creating
+.
+.TP
+.B create=tdp | top\-down\-parent
+Selects the highest writable branch where the parent dir exists. If
+the parent dir does not exist on a writable branch, then the internal
+copyup will happen. The policy for this copyup is always \[oq]bottom-up.\[cq]
+This is the default policy.
+.
+.TP
+.B create=rr | round\-robin
+Selects a writable branch in round robin. When you have two writable
+branches and creates 10 new files, 5 files will be created for each
+branch.
+mkdir(2) systemcall is an exception. When you create 10 new directories,
+all are created on the same branch.
+.
+.TP
+.B create=mfs[:second] | most\-free\-space[:second]
+Selects a writable branch which has most free space. In order to keep
+the performance, you can specify the duration (\[oq]second\[cq]) which makes
+aufs hold the index of last selected writable branch until the
+specified seconds expires. The first time you create something in aufs
+after the specified seconds expired, aufs checks the amount of free
+space of all writable branches by internal statfs call
+and the held branch index will be updated.
+The default value is \*[AUFS_MFS_SECOND_DEF] seconds.
+.
+.TP
+.B create=mfsrr:low[:second]
+Selects a writable branch in most-free-space mode first, and then
+round-robin mode. If the selected branch has less free space than the
+specified value \[oq]low\[cq] in bytes, then aufs re-tries in round-robin mode.
+.\" \[oq]G\[cq], \[oq]M\[cq] and \[oq]K\[cq] (case insensitive) can be followed after \[oq]low.\[cq] Or
+Try an arithmetic expansion of shell which is defined by POSIX.
+For example, $((10 * 1024 * 1024)) for 10M.
+You can also specify the duration (\[oq]second\[cq]) which is equivalent to
+the \[oq]mfs\[cq] mode.
+.
+.TP
+.B create=pmfs[:second]
+Selects a writable branch where the parent dir exists, such as tdp
+mode. When the parent dir exists on multiple writable branches, aufs
+selects the one which has most free space, such as mfs mode.
+
+.SS Policies for Copy-Up
+.
+.TP
+.B cpup=tdp | top\-down\-parent
+Equivalent to the same named policy for create.
+This is the default policy.
+.
+.TP
+.B cpup=bup | bottom\-up\-parent
+Selects the writable branch where the parent dir exists and the branch
+is nearest upper one from the copyup-source.
+.
+.TP
+.B cpup=bu | bottom\-up
+Selects the nearest upper writable branch from the copyup-source,
+regardless the existence of the parent dir.
+
+.\" ----------------------------------------------------------------------
+.SH Exporting Aufs via NFS
+Aufs is supporting NFS-exporting.
+Since aufs has no actual block device, you need to add NFS \[oq]fsid\[cq] option at
+exporting. Refer to the manual of NFS about the detail of this option.
+
+There are some limitations or requirements.
+.RS
+.Bu
+The branch filesystem must support NFS-exporting.
+.Bu
+NFSv2 is not supported. When you mount the exported aufs from your NFS
+client, you will need to some NFS options like v3 or nfsvers=3,
+especially if it is nfsroot.
+.Bu
+If the size of the NFS file handle on your branch filesystem is large,
+aufs will
+not be able to handle it. The maximum size of NFSv3 file
+handle for a filesystem is 64 bytes. Aufs uses 24 bytes for 32bit
+system, plus 12 bytes for 64bit system. The rest is a room for a file
+handle of a branch filesystem.
+.Bu
+The External Inode Number Bitmap, Translation Table and Generation Table
+(xino) is
+required since NFS file
+handle is based upon inode number. The mount option \[oq]xino\[cq] is enabled
+by default.
+The external inode generation table and its debugfs entry
+(<debugfs>/aufs/si_*/xigen) is created when CONFIG_AUFS_EXPORT is
+enabled even if you don\[aq]t export aufs actually.
+The size of the external inode generation table grows only, never be
+truncated. You might need to pay attention to the free space of the
+filesystem where xino files are placed. By default, it is the first
+writable branch.
+.Bu
+The branch filesystems must be accessible, which means \[oq]not hidden.\[cq]
+It means you need to \[oq]mount \-\-move\[cq] when you use initramfs and
+switch_root(8), or chroot(8).
+.RE
+
+.\" ----------------------------------------------------------------------
+.SH Dentry and Inode Caches
+If you want to clear caches on your system, there are several tricks
+for that. If your system ram is low,
+try \[oq]find /large/dir \-ls > /dev/null\[cq].
+It will read many inodes and dentries and cache them. Then old caches will be
+discarded.
+But when you have large ram or you do not have such large
+directory, it is not effective.
+
+If you want to discard cache within a certain filesystem,
+try \[oq]mount \-o remount /your/mntpnt\[cq]. Some filesystem may return an error of
+EINVAL or something, but VFS discards the unused dentry/inode caches on the
+specified filesystem.
+
+.\" ----------------------------------------------------------------------
+.SH Compatible/Incompatible with Unionfs Version 1.x Series
+If you compile aufs with \-DCONFIG_AUFS_COMPAT, dirs= option and =nfsro
+branch permission flag are available. They are interpreted as
+br: option and =ro flags respectively.
+ \[oq]debug\[cq], \[oq]delete\[cq], \[oq]imap\[cq] options are ignored silently. When you
+compile aufs without \-DCONFIG_AUFS_COMPAT, these three options are
+also ignored, but a warning message is issued.
+
+Ignoring \[oq]delete\[cq] option, and to keep filesystem consistency, aufs tries
+writing something to only one branch in a single systemcall. It means
+aufs may copyup even if the copyup-src branch is specified as writable.
+For example, you have two writable branches and a large regular file
+on the lower writable branch. When you issue rename(2) to the file on aufs,
+aufs may copyup it to the upper writable branch.
+If this behaviour is not what you want, then you should rename(2) it
+on the lower branch directly.
+
+And there is a simple shell
+script \[oq]unionctl\[cq] under sample subdirectory, which is compatible with
+unionctl(8) in
+Unionfs Version 1.x series, except \-\-query action.
+This script executes mount(8) with \[oq]remount\[cq] option and uses
+add/del/mod aufs mount options.
+If you are familiar with Unionfs Version 1.x series and want to use unionctl(8), you can
+try this script instead of using mount \-o remount,... directly.
+Aufs does not support ioctl(2) interface.
+This script is highly depending upon mount(8) in
+util\-linux\-2.12p package, and you need to mount /proc to use this script.
+If your mount(8) version differs, you can try modifying this
+script. It is very easy.
+The unionctl script is just for a sample usage of aufs remount
+interface.
+
+Aufs uses the external inode number bitmap and translation table by
+default.
+
+The default branch permission for the first branch is \[oq]rw\[cq], and the
+rest is \[oq]ro.\[cq]
+
+The whiteout is for hiding files on lower branches. Also it is applied
+to stop readdir going lower branches.
+The latter case is called \[oq]opaque directory.\[cq] Any
+whiteout is an empty file, it means whiteout is just an mark.
+In the case of hiding lower files, the name of whiteout is
+\[oq]\*[AUFS_WH_PFX]<filename>.\[cq]
+And in the case of stopping readdir, the name is
+\[oq]\*[AUFS_WH_PFX]\*[AUFS_WH_PFX].opq\[cq] or
+\[oq]\*[AUFS_WH_PFX]__dir_opaque.\[cq] The name depends upon your compile
+configuration
+CONFIG_AUFS_COMPAT.
+.\" All of newly created or renamed directory will be opaque.
+All whiteouts are hardlinked,
+including \[oq]<writable branch top dir>/\*[AUFS_WH_BASE].\[cq]
+
+The hardlink on an ordinary (disk based) filesystem does not
+consume inode resource newly. But in linux tmpfs, the number of free
+inodes will be decremented by link(2). It is recommended to specify
+nr_inodes option to your tmpfs if you meet ENOSPC. Use this option
+after checking by \[oq]df \-i.\[cq]
+
+When you rmdir or rename-to the dir who has a number of whiteouts,
+aufs rename the dir to the temporary whiteouted-name like
+\[oq]\*[AUFS_WH_PFX]<dir>.<random hex>.\[cq] Then remove it after actual operation.
+cf. mount option \[oq]dirwh.\[cq]
+
+.\" ----------------------------------------------------------------------
+.SH Incompatible with an Ordinary Filesystem
+stat(2) returns the inode info from the first existence inode among
+the branches, except the directory link count.
+Aufs computes the directory link count larger than the exact value usually, in
+order to keep UNIX filesystem semantics, or in order to shut find(1) mouth up.
+The size of a directory may be wrong too, but it has to do no harm.
+The timestamp of a directory will not be updated when a file is
+created or removed under it, and it was done on a lower branch.
+
+The test for permission bits has two cases. One is for a directory,
+and the other is for a non-directory. In the case of a directory, aufs
+checks the permission bits of all existing directories. It means you
+need the correct privilege for the directories including the lower
+branches.
+The test for a non-directory is more simple. It checks only the
+topmost inode.
+
+statfs(2) returns the information of the first branch info except
+namelen when \[oq]nosum\[cq] is specified (the default). The namelen is
+decreased by the whiteout prefix length. And the block size may differ
+from st_blksize which is obtained by stat(2).
+
+Remember, seekdir(3) and telldir(3) are not defined in POSIX. They may
+not work as you expect. Try rewinddir(3) or re-open the dir.
+
+The whiteout prefix (\*[AUFS_WH_PFX]) is reserved on all branches. Users should
+not handle the filename begins with this prefix.
+In order to future whiteout, the maxmum filename length is limited by
+the longest value \- \*[AUFS_WH_PFX_LEN]. It may be a violation of POSIX.
+
+If you dislike the difference between the aufs entries in /etc/mtab
+and /proc/mounts, and if you are using mount(8) in util\-linux package,
+then try ./mount.aufs utility. Copy the script to /sbin/mount.aufs.
+This simple utility tries updating
+/etc/mtab. If you do not care about /etc/mtab, you can ignore this
+utility.
+Remember this utility is highly depending upon mount(8) in
+util\-linux\-2.12p package, and you need to mount /proc.
+
+Since aufs uses its own inode and dentry, your system may cache huge
+number of inodes and dentries. It can be as twice as all of the files
+in your union.
+It means that unmounting or remounting readonly at shutdown time may
+take a long time, since mount(2) in VFS tries freeing all of the cache
+on the target filesystem.
+
+When you open a directory, aufs will open several directories
+internally.
+It means you may reach the limit of the number of file descriptor.
+And when the lower directory cannot be opened, aufs will close all the
+opened upper directories and return an error.
+
+The sub-mount under the branch
+of local filesystem
+is ignored.
+For example, if you have mount another filesystem on
+/branch/another/mntpnt, the files under \[oq]mntpnt\[cq] will be ignored by aufs.
+It is recommended to mount the sub-mount under the mounted aufs.
+For example,
+
+.nf
+# sudo mount /dev/sdaXX /ro_branch
+# d=another/mntpnt
+# sudo mount /dev/sdbXX /ro_branch/$d
+# mkdir -p /rw_branch/$d
+# sudo mount -t aufs -o br:/rw_branch:/ro_branch none /aufs
+# sudo mount -t aufs -o br:/rw_branch/${d}:/ro_branch/${d} none /aufs/another/$d
+.fi
+
+There are several characters which are not allowed to use in a branch
+directory path and xino filename. See detail in Branch Syntax and Mount
+Option.
+
+The file-lock which means fcntl(2) with F_SETLK, F_SETLKW or F_GETLK, flock(2)
+and lockf(3), is applied to virtual aufs file only, not to the file on a
+branch. It means you can break the lock by accessing a branch directly.
+TODO: check \[oq]security\[cq] to hook locks, as inotify does.
+
+The I/O to the named pipe or local socket are not handled by aufs, even
+if it exists in aufs. After the reader and the writer established their
+connection if the pipe/socket are copied-up, they keep using the old one
+instead of the copied-up one.
+
+The fsync(2) and fdatasync(2) systemcalls return 0 which means success, even
+if the given file descriptor is not opened for writing.
+I am afraid this behaviour may violate some standards. Checking the
+behaviour of fsync(2) on ext2, aufs decided to return success.
+
+If you want to use disk-quota, you should set it up to your writable
+branch since aufs does not have its own block device.
+
+When your aufs is the root directory of your system, and your system
+tells you some of the filesystem were not unmounted cleanly, try these
+procedure when you shutdown your system.
+.nf
+# mount -no remount,ro /
+# for i in $writable_branches
+# do mount -no remount,ro $i
+# done
+.fi
+If your xino file is on a hard drive, you also need to specify
+\[oq]noxino\[cq] option or \[oq]xino=/your/tmpfs/xino\[cq] at remounting root
+directory.
+
+To rename(2) directory may return EXDEV even if both of src and tgt
+are on the same aufs. When the rename-src dir exists on multiple
+branches and the lower dir has child(ren), aufs has to copyup all his
+children. It can be recursive copyup. Current aufs does not support
+such huge copyup operation at one time in kernel space, instead
+produces a warning and returns EXDEV.
+Generally, mv(1) detects this error and tries mkdir(2) and
+rename(2) or copy/unlink recursively. So the result is harmless.
+If your application which issues rename(2) for a directory does not
+support EXDEV, it will not work on aufs.
+Also this specification is applied to the case when the src directroy
+exists on the lower readonly branch and it has child(ren).
+
+If a sudden accident such like a power failure happens during aufs is
+performing, and regular fsck for branch filesystems is completed after
+the disaster, you need to extra fsck for aufs writable branches. It is
+necessary to check whether the whiteout remains incorrectly or not,
+eg. the real filename and the whiteout for it under the same parent
+directory. If such whiteout remains, aufs cannot handle the file
+correctly.
+To check the consistency from the aufs\[aq] point of view, you can use a
+simple shell script called /sbin/auchk. Its purpose is a fsck tool for
+aufs, and it checks the illegal whiteout, the remained
+pseudo-links and the remained aufs-temp files. If they are found, the
+utility reports you and asks whether to delete or not.
+It is recommended to execute /sbin/auchk for every writable branch
+filesystem before mouting aufs if the system experienced crash.
+
+
+.\" ----------------------------------------------------------------------
+.SH EXAMPLES
+The mount options are interpreted from left to right at remount-time.
+These examples
+shows how the options are handled. (assuming /sbin/mount.aufs was
+installed)
+
+.nf
+# mount -v -t aufs br:/day0:/base none /u
+none on /u type aufs (rw,xino=/day0/.aufs.xino,br:/day0=rw:/base=ro)
+# mount -v -o remount,\\
+       prepend:/day1,\\
+       xino=/day1/xino,\\
+       mod:/day0=ro,\\
+       del:/day0 \\
+       /u
+none on /u type aufs (rw,xino=/day1/xino,br:/day1=rw:/base=ro)
+.fi
+
+.nf
+# mount -t aufs br:/rw none /u
+# mount -o remount,append:/ro /u
+different uid/gid/permission, /ro
+# mount -o remount,del:/ro /u
+# mount -o remount,nowarn_perm,append:/ro /u
+#
+(there is no warning)
+.fi
+
+.\" If you want to expand your filesystem size, aufs may help you by
+.\" adding an writable branch. Since aufs supports multiple writable
+.\" branches, the old writable branch can be being writable, if you want.
+.\" In this example, any modifications to the files under /ro branch will
+.\" be copied-up to /new, but modifications to the files under /rw branch
+.\" will not.
+.\" And the next example shows the modifications to the files under /rw branch
+.\" will be copied-up to /new/a.
+.\"
+.\" Todo: test multiple writable branches policy. cpup=nearest, cpup=exist_parent.
+.\"
+.\" .nf
+.\" # mount -v -t aufs br:/rw:/ro none /u
+.\" none on /u type aufs (rw,xino=/rw/.aufs.xino,br:/rw=rw:/ro=ro)
+.\" # mkfs /new
+.\" # mount -v -o remount,add:1:/new=rw /u
+.\" none on /u type aufs (rw,xino=/rw/.aufs.xino,br:/rw=rw:/new=rw:/ro=ro)
+.\" .fi
+.\"
+.\" .nf
+.\" # mount -v -t aufs br:/rw:/ro none /u
+.\" none on /u type aufs (rw,xino=/rw/.aufs.xino,br:/rw=rw:/ro=ro)
+.\" # mkfs /new
+.\" # mkdir /new/a new/b
+.\" # mount -v -o remount,add:1:/new/b=rw,prepend:/new/a,mod:/rw=ro /u
+.\" none on /u type aufs (rw,xino=/rw/.aufs.xino,br:/new/a=rw:/rw=ro:/new/b=rw:/ro=ro)
+.\" .fi
+
+When you use aufs as root filesystem, it is recommended to consider to
+exclude some directories. For example, /tmp and /var/log are not need
+to stack in many cases. They do not usually need to copyup or to whiteout.
+Also the swapfile on aufs (a regular file, not a block device) is not
+supported.
+In order to exclude the specific dir from aufs, try bind mounting.
+
+And there is a good sample which is for network booted diskless machines. See
+sample/ in detail.
+
+.\" ----------------------------------------------------------------------
+.SH DIAGNOSTICS
+When you add a branch to your union, aufs may warn you about the
+privilege or security of the branch, which is the permission bits,
+owner and group of the top directory of the branch.
+For example, when your upper writable branch has a world writable top
+directory,
+a malicious user can create any files on the writable branch directly,
+like copyup and modify manually. I am afraid it can be a security
+issue.
+
+When you mount or remount your union without \-o ro common mount option
+and without writable branch, aufs will warn you that the first branch
+should be writable.
+
+.\" It is discouraged to set both of \[oq]udba\[cq] and \[oq]noxino\[cq] mount options. In
+.\" this case the inode number under aufs will always be changed and may
+.\" reach the end of inode number which is a maximum of unsigned long. If
+.\" the inode number reaches the end, aufs will return EIO repeatedly.
+
+When you set udba other than inotify and change something on your
+branch filesystem directly, later aufs may detect some mismatches to
+its cache. If it is a critical mismatch, aufs returns EIO.
+
+When an error occurs in aufs, aufs prints the kernel message with
+\[oq]errno.\[cq] The priority of the message (log level) is ERR or WARNING which
+depends upon the message itself.
+You can convert the \[oq]errno\[cq] into the error message by perror(3),
+strerror(3) or something.
+For example, the \[oq]errno\[cq] in the message \[oq]I/O Error, write failed (\-28)\[cq]
+is 28 which means ENOSPC or \[oq]No space left on device.\[cq]
+
+When CONFIG_AUFS_BR_RAMFS is enabled, you can specify ramfs as an aufs
+branch. Since ramfs is simple, it does not set the maximum link count
+originally. In aufs, it is very dangerous, particulary for
+whiteouts. Finally aufs sets the maxmimum link count for ramfs. Tha
+value is 32000 which is borrowed from ext2.
+
+
+.\" .SH Current Limitation
+.
+.\" ----------------------------------------------------------------------
+.\" SYNOPSIS
+.\" briefly describes the command or function\[aq]s interface.  For  commands,  this
+.\" shows the syntax of the command and its arguments (including options); bold-
+.\" face is used for as-is text and italics are  used  to  indicate  replaceable
+.\" arguments. Brackets ([]) surround optional arguments, vertical bars (|) sep-
+.\" arate choices, and ellipses (...) can be repeated.  For functions, it  shows
+.\" any required data declarations or #include directives, followed by the func-
+.\" tion declaration.
+.
+.\" DESCRIPTION
+.\" gives an explanation of what the command, function, or format does.  Discuss
+.\" how  it  interacts  with  files  and standard input, and what it produces on
+.\" standard output  or  standard  error.   Omit  internals  and  implementation
+.\" details  unless  they\[aq]re critical for understanding the interface.  Describe
+.\" the usual case; for information on options  use  the  OPTIONS  section.   If
+.\" there  is some kind of input grammar or complex set of subcommands, consider
+.\" describing them in a separate USAGE section (and just place an  overview  in
+.\" the DESCRIPTION section).
+.
+.\" RETURN VALUE
+.\" gives a list of the values the library routine will return to the caller and
+.\" the conditions that cause these values to be returned.
+.
+.\" EXIT STATUS
+.\" lists the possible exit status values or a program and the  conditions  that
+.\" cause these values to be returned.
+.
+.\" USAGE
+.\" describes the grammar of any sublanguage this implements.
+.
+.\" FILES
+.\" lists  the  files the program or function uses, such as configuration files,
+.\" startup files, and files the program directly operates on.   Give  the  full
+.\" pathname  of  these  files,  and  use the installation process to modify the
+.\" directory part to match user preferences.  For many  programs,  the  default
+.\" installation  location is in /usr/local, so your base manual page should use
+.\" /usr/local as the base.
+.
+.\" ENVIRONMENT
+.\" lists all environment variables that affect your program or function and how
+.\" they affect it.
+.
+.\" SECURITY
+.\" discusses security issues and implications.  Warn  about  configurations  or
+.\" environments  that should be avoided, commands that may have security impli-
+.\" cations, and so on, especially if they aren\[aq]t obvious.  Discussing  security
+.\" in  a  separate section isn\[aq]t necessary; if it\[aq]s easier to understand, place
+.\" security information in the other sections (such as the DESCRIPTION or USAGE
+.\" section).  However, please include security information somewhere!
+.
+.\" CONFORMING TO
+.\" describes any standards or conventions this implements.
+.
+.\" NOTES
+.\" provides miscellaneous notes.
+.
+.\" BUGS
+.\" lists  limitations,  known defects or inconveniences, and other questionable
+.\" activities.
+
+.SH COPYRIGHT
+Copyright \(co 2005\-2009 Junjiro R. Okajima
+
+.SH AUTHOR
+Junjiro R. Okajima
+
+.\" SEE ALSO
+.\" lists  related  man  pages in alphabetical order, possibly followed by other
+.\" related pages or documents.  Conventionally this is the last section.
diff --git a/Documentation/filesystems/aufs/design/01intro.txt b/Documentation/filesystems/aufs/design/01intro.txt
new file mode 100644
index 0000000..4955fdc
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/01intro.txt
@@ -0,0 +1,128 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+Introduction
+----------------------------------------
+
+aufs [ei ju: ef es] | [a u f s]
+1. abbrev. for "advanced multi-layered unification filesystem".
+2. abbrev. for "another unionfs".
+3. abbrev. for "auf das" in German which means "on the" in English.
+   Ex. "Butter aufs Brot"(G) means "butter onto bread"(E).
+   But "Filesystem aufs Filesystem" is hard to understand.
+
+AUFS is a filesystem with features:
+- multi layered stackable unification filesystem, the member directory
+  is called as a branch.
+- branch permission and attribute, 'readonly', 'real-readonly',
+  'readwrite', 'whiteout-able', 'link-able whiteout' and their
+  combination.
+- internal "file copy-on-write".
+- logical deletion, whiteout.
+- dynamic branch manipulation, adding, deleting and changing permission.
+- allow bypassing aufs, user's direct branch access.
+- external inode number translation table and bitmap which maintains the
+  persistent aufs inode number.
+- seekable directory, including NFS readdir.
+- file mapping, mmap and sharing pages.
+- pseudo-link, hardlink over branches.
+- loopback mounted filesystem as a branch.
+- several policies to select one among multiple writable branches.
+- revert a single systemcall when an error occurs in aufs.
+- and more...
+
+
+Multi Layered Stackable Unification Filesystem
+----------------------------------------------------------------------
+Most people already knows what it is.
+It is a filesystem which unifies several directories and provides a
+merged single directory. When users access a file, the access will be
+passed/re-directed/converted (sorry, I am not sure which English word is
+correct) to the real file on the member filesystem. The member
+filesystem is called 'lower filesystem' or 'branch' and has a mode
+'readonly' and 'readwrite.' And the deletion for a file on the lower
+readonly branch is handled by creating 'whiteout' on the upper writable
+branch.
+
+On LKML, there have been discussions about UnionMount (Jan Blunck and
+Bharata B Rao) and Unionfs (Erez Zadok). They took different approaches
+to implement the merged-view.
+The former tries putting it into VFS, and the latter implements as a
+separate filesystem.
+(If I misunderstand about these implementations, please let me know and
+I shall correct it. Because it is a long time ago when I read their
+source files last time).
+UnionMount's approach will be able to small, but may be hard to share
+branches between several UnionMount since the whiteout in it is
+implemented in the inode on branch filesystem and always
+shared. According to Bharata's post, readdir does not seems to be
+finished yet.
+Unionfs has a longer history. When I started implementing a stacking filesystem
+(Aug 2005), it already existed. It has virtual super_block, inode,
+dentry and file objects and they have an array pointing lower same kind
+objects. After contributing many patches for Unionfs, I re-started my
+project AUFS (Jun 2006).
+
+In AUFS, the structure of filesystem resembles to Unionfs, but I
+implemented my own ideas, approaches and enhancements and it became
+totally different one.
+
+
+Several characters/aspects of aufs
+----------------------------------------------------------------------
+
+Aufs has several characters or aspects.
+1. a filesystem, callee of VFS helper
+2. sub-VFS, caller of VFS helper for branches
+3. a virtual filesystem which maintains persistent inode number
+4. reader/writer of files on branches such like an application
+
+1. Caller of VFS Helper
+As an ordinary linux filesystem, aufs is a callee of VFS. For instance,
+unlink(2) from an application reaches sys_unlink() kernel function and
+then vfs_unlink() is called. vfs_unlink() is one of VFS helper and it
+calls filesystem specific unlink operation. Actually aufs implements the
+unlink operation but it behaves like a redirector.
+
+2. Caller of VFS Helper for Branches
+aufs_unlink() passes the unlink request to the branch filesystem as if
+it were called from VFS. So the called unlink operation of the branch
+filesystem acts as usual. As a caller of VFS helper, aufs should handle
+every necessary pre/post operation for the branch filesystem.
+- acquire the lock for the parent dir on a branch
+- lookup in a branch
+- revalidate dentry on a branch
+- mnt_want_write() for a branch
+- vfs_unlink() for a branch
+- mnt_drop_write() for a branch
+- release the lock on a branch
+
+3. Persistent Inode Number
+One of the most important issue for a filesystem is to maintain inode
+numbers. This is particularly important to support exporting a
+filesystem via NFS. Aufs is a virtual filesystem which doesn't have a
+backend block device for its own. But some storage is necessary to
+maintain inode number. It may be a large space and may not suit to keep
+in memory. Aufs rents some space from its first writable branch
+filesystem (by default) and creates file(s) on it. These files are
+created by aufs internally and removed soon (currently) keeping opened.
+Note: Because these files are removed, they are totally gone after
+      unmounting aufs. It means the inode numbers are not persistent
+      across unmount or reboot. I have a plan to make them really
+      persistent which will be important for aufs on NFS server.
+
+4. Read/Write Files Internally (copy-on-write)
+Because a branch can be readonly, when you write a file on it, aufs will
+"copy-up" it to the upper writable branch internally. And then write the
+originally requested thing to the file. Generally kernel doesn't
+open/read/write file actively. In aufs, even a single write may cause a
+internal "file copy". This behaviour is very similar to cp(1) command.
+
+Some people may think it is better to pass such work to user space
+helper, instead of doing in kernel space. Actually I am still thinking
+about it. But currently I have implemented it in kernel space.
diff --git a/Documentation/filesystems/aufs/design/02struct.txt b/Documentation/filesystems/aufs/design/02struct.txt
new file mode 100644
index 0000000..6db666b
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/02struct.txt
@@ -0,0 +1,205 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+Basic Aufs Internal Structure
+
+Superblock/Inode/Dentry/File Objects
+----------------------------------------------------------------------
+As like an ordinary filesystem, aufs has its own
+superblock/inode/dentry/file objects. All these objects have a
+dynamically allocated array and store the same kind of pointers to the
+lower filesystem, branch.
+For example, when you build a union with one readwrite branch and one
+readonly, mounted /au, /rw and /ro respectively.
+- /au = /rw + /ro
+- /ro/fileA exists but /rw/fileA
+
+Aufs lookup operation finds /ro/fileA and gets dentry for that. These
+pointers are stored in a aufs dentry. The array in aufs dentry will be,
+- [0] = NULL
+- [1] = /ro/fileA
+
+This style of an array is essentially same to the aufs
+superblock/inode/dentry/file objects.
+
+Because aufs supports manipulating branches, ie. add/delete/change
+dynamically, these objects has its own generation. When branches are
+changed, the generation in aufs superblock is incremented. And a
+generation in other object are compared when it is accessed.
+When a generation in other objects are obsoleted, aufs refreshes the
+internal array.
+
+
+Superblock
+----------------------------------------------------------------------
+Additionally aufs superblock has some data for policies to select one
+among multiple writable branches, XIB files, pseudo-links and kobject.
+See below in detail.
+About the policies which supports copy-down a directory, see policy.txt
+too.
+
+
+Branch and XINO(External Inode Number Translation Table)
+----------------------------------------------------------------------
+Every branch has its own xino (external inode number translation table)
+file. The xino file is created and unlinked by aufs internally. When two
+members of a union exist on the same filesystem, they share the single
+xino file.
+The struct of a xino file is simple, just a sequence of aufs inode
+numbers which is indexed by the lower inode number.
+In the above sample, assume the inode number of /ro/fileA is i111 and
+aufs assigns the inode number i999 for fileA. Then aufs writes 999 as
+4(8) bytes at 111 * 4(8) bytes offset in the xino file.
+
+When the inode numbers are not contiguous, the xino file will be sparse
+which has a hole in it and doesn't consume as much disk space as it
+might appear. If your branch filesystem consumes disk space for such
+holes, then you should specify 'xino=' option at mounting aufs.
+
+Also a writable branch has three kinds of "whiteout bases". All these
+are existed when the branch is joined to aufs and the names are
+whiteout-ed doubly, so that users will never see their names in aufs
+hierarchy.
+1. a regular file which will be linked to all whiteouts.
+2. a directory to store a pseudo-link.
+3. a directory to store an "orphan-ed" file temporary.
+
+1. Whiteout Base
+   When you remove a file on a readonly branch, aufs handles it as a
+   logical deletion and creates a whiteout on the upper writable branch
+   as a hardlink of this file in order not to consume inode on the
+   writable branch.
+2. Pseudo-link Dir
+   See below, Pseudo-link.
+3. Step-Parent Dir
+   When "fileC" exists on the lower readonly branch only and it is
+   opened and removed with its parent dir, and then user writes
+   something into it, then aufs copies-up fileC to this
+   directory. Because there is no other dir to store fileC. After
+   creating a file under this dir, the file is unlinked.
+
+Because aufs supports manipulating branches, ie. add/delete/change
+dynamically, a branch has its own id. When the branch order changes, aufs
+finds the new index by searching the branch id.
+
+
+Pseudo-link
+----------------------------------------------------------------------
+Assume "fileA" exists on the lower readonly branch only and it is
+hardlinked to "fileB" on the branch. When you write something to fileA,
+aufs copies-up it to the upper writable branch. Additionally aufs
+creates a hardlink under the Pseudo-link Directory of the writable
+branch. The inode of a pseudo-link is kept in aufs super_block as a
+simple list. If fileB is read after unlinking fileA, aufs returns
+filedata from the pseudo-link instead of the lower readonly
+branch. Because the pseudo-link is based upon the inode, to keep the
+inode number by xino (see above) is important.
+
+All the hardlinks under the Pseudo-link Directory of the writable branch
+should be restored in a proper location later. Aufs provides a utility
+to do this. The userspace helpers executed at remounting and unmounting
+aufs by default.
+
+
+XIB(external inode number bitmap)
+----------------------------------------------------------------------
+Addition to the xino file per a branch, aufs has an external inode number
+bitmap in a superblock object. It is also a file such like a xino file.
+It is a simple bitmap to mark whether the aufs inode number is in-use or
+not.
+To reduce the file I/O, aufs prepares a single memory page to cache xib.
+
+Aufs implements a feature to truncate/refresh both of xino and xib to
+reduce the number of consumed disk blocks for these files.
+
+
+Virtual or Vertical Dir
+----------------------------------------------------------------------
+In order to support multiple layers (branches), aufs readdir operation
+constructs a virtual dir block on memory. For readdir, aufs calls
+vfs_readdir() internally for each dir on branches, merges their entries
+with eliminating the whiteout-ed ones, and sets it to file (dir)
+object. So the file object has its entry list until it is closed. The
+entry list will be updated when the file position is zero and becomes
+old. This decision is made in aufs automatically.
+
+The dynamically allocated memory block for the name of entries has a
+unit of 512 bytes (by default) and stores the names contiguously (no
+padding). Another block for each entry is handled by kmem_cache too.
+During building dir blocks, aufs creates hash list and judging whether
+the entry is whiteouted by its upper branch or already listed.
+
+Some people may call it can be a security hole or invite DoS attack
+since the opened and once readdir-ed dir (file object) holds its entry
+list and becomes a pressure for system memory. But I'd say it is similar
+to files under /proc or /sys. The virtual files in them also holds a
+memory page (generally) while they are opened. When an idea to reduce
+memory for them is introduced, it will be applied to aufs too.
+
+
+Workqueue
+----------------------------------------------------------------------
+Aufs sometimes requires privilege access to a branch. For instance,
+in copy-up/down operation. When a user process is going to make changes
+to a file which exists in the lower readonly branch only, and the mode
+of one of ancestor directories may not be writable by a user
+process. Here aufs copy-up the file with its ancestors and they may
+require privilege to set its owner/group/mode/etc.
+This is a typical case of a application character of aufs (see
+Introduction).
+
+Aufs uses workqueue synchronously for this case. It creates its own
+workqueue. The workqueue is a kernel thread and has privilege. Aufs
+passes the request to call mkdir or write (for example), and wait for
+its completion. This approach solves a problem of a signal handler
+simply.
+If aufs didn't adopt the workqueue and changed the privilege of the
+process, and if the mkdir/write call arises SIGXFSZ or other signal,
+then the user process might gain a privilege or the generated core file
+was owned by a superuser. But I have a plan to switch to a new
+credential approach which will be introduced in linux-2.6.29.
+
+Also aufs uses the system global workqueue ("events" kernel thread) too
+for asynchronous tasks, such like handling inotify, re-creating a
+whiteout base and etc. This is unrelated to a privilege.
+Most of aufs operation tries acquiring a rw_semaphore for aufs
+superblock at the beginning, at the same time waits for the completion
+of all queued asynchronous tasks.
+
+
+Whiteout
+----------------------------------------------------------------------
+The whiteout in aufs is very similar to Unionfs's. That is represented
+by its filename. UnionMount takes an approach of a file mode, but I am
+afraid several utilities (find(1) or something) will have to support it.
+
+Basically the whiteout represents "logical deletion" which stops aufs to
+lookup further, but also it represents "dir is opaque" which also stop
+lookup.
+
+In aufs, rmdir(2) and rename(2) for dir uses whiteout alternatively.
+In order to make several functions in a single systemcall to be
+revertible, aufs adopts an approach to rename a directory to a temporary
+unique whiteouted name.
+For example, in rename(2) dir where the target dir already existed, aufs
+renames the target dir to a temporary unique whiteouted name before the
+actual rename on a branch and then handles other actions (make it opaque,
+update the attributes, etc). If an error happens in these actions, aufs
+simply renames the whiteouted name back and returns an error. If all are
+succeeded, aufs registers a function to remove the whiteouted unique
+temporary name completely and asynchronously to the system global
+workqueue.
+
+
+Copy-up
+----------------------------------------------------------------------
+It is a well-known feature or concept.
+When user modifies a file on a readonly branch, aufs operate "copy-up"
+internally and makes change to the new file on the upper writable branch.
+When the trigger systemcall does not update the timestamps of the parent
+dir, aufs reverts it after copy-up.
diff --git a/Documentation/filesystems/aufs/design/03lookup.txt b/Documentation/filesystems/aufs/design/03lookup.txt
new file mode 100644
index 0000000..36ddac7
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/03lookup.txt
@@ -0,0 +1,95 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+Lookup in a Branch
+----------------------------------------------------------------------
+Since aufs has a character of sub-VFS (see Introduction), it operates
+lookup for branches as VFS does. It may be a heavy work. Generally
+speaking struct nameidata is a bigger structure and includes many
+information. But almost all lookup operation in aufs is the simplest
+case, ie. lookup only an entry directly connected to its parent. Digging
+down the directory hierarchy is unnecessary.
+
+VFS has a function lookup_one_len() for that use, but it is not usable
+for a branch filesystem which requires struct nameidata. So aufs
+implements a simple lookup wrapper function. When a branch filesystem
+allows NULL as nameidata, it calls lookup_one_len(). Otherwise it builds
+a simplest nameidata and calls lookup_hash().
+Here aufs applies "a principle in NFSD", ie. if the filesystem supports
+NFS-export, then it has to support NULL as a nameidata parameter for
+->create(), ->lookup() and ->d_revalidate(). So the lookup wrapper in
+aufs tests if ->s_export_op in the branch is NULL or not.
+
+When a branch is a remote filesystem, aufs trusts its ->d_revalidate().
+For d_revalidate, aufs implements three levels of revalidate tests. See
+"Revalidate Dentry and UDBA" in detail.
+
+
+Loopback Mount
+----------------------------------------------------------------------
+Basically aufs supports any type of filesystem and block device for a
+branch (actually there are some exceptions). But it is prohibited to add
+a loopback mounted one whose backend file exists in a filesystem which is
+already added to aufs. The reason is to protect aufs from a recursive
+lookup. If it was allowed, the aufs lookup operation might re-enter a
+lookup for the loopback mounted branch in the same context, and will
+cause a deadlock.
+
+
+Revalidate Dentry and UDBA (User's Direct Branch Access)
+----------------------------------------------------------------------
+Generally VFS helpers re-validate a dentry as a part of lookup.
+0. digging down the directory hierarchy.
+1. lock the parent dir by its i_mutex.
+2. lookup the final (child) entry.
+3. revalidate it.
+4. call the actual operation (create, unlink, etc.)
+5. unlock the parent dir
+
+If the filesystem implements its ->d_revalidate() (step 3), then it is
+called. Actually aufs implements it and checks the dentry on a branch is
+still valid.
+But it is not enough. Because aufs has to release the lock for the
+parent dir on a branch at the end of ->lookup() (step 2) and
+->d_revalidate() (step 3) while the i_mutex of the aufs dir is still
+held by VFS.
+If the file on a branch is changed directly, eg. bypassing aufs, after
+aufs released the lock, then the subsequent operation may cause
+something unpleasant result.
+
+This situation is a result of VFS architecture, ->lookup() and
+->d_revalidate() is separated. But I never say it is wrong. It is a good
+design from VFS's point of view. It is just not suitable for sub-VFS
+character in aufs.
+
+Aufs supports such case by three level of revalidation which is
+selectable by user.
+1. Simple Revalidate
+   Addition to the native flow in VFS's, confirm the child-parent
+   relationship on the branch just after locking the parent dir on the
+   branch in the "actual operation" (step 4). When this validation
+   fails, aufs returns EBUSY. ->d_revalidate() (step 3) in aufs still
+   checks the validation of the dentry on branches.
+2. Monitor Changes Internally by Inotify
+   Addition to above, in the "actual operation" (step 4) aufs re-lookup
+   the dentry on the branch, and returns EBUSY if it finds different
+   dentry.
+   Additionally, aufs sets the inotify watch for every dir on branches
+   during it is in cache. When the event is notified, aufs registers a
+   function to kernel 'events' thread by schedule_work(). And the
+   function sets some special status to the cached aufs dentry and inode
+   private data. If they are not cached, then aufs has nothing to
+   do. When the same file is accessed through aufs (step 0-3) later,
+   aufs will detect the status and refresh all necessary data.
+   In this mode, aufs has to ignore the event which is fired by aufs
+   itself.
+3. No Extra Validation
+   This is the simplest test and doesn't add any additional revalidation
+   test, and skip therevalidatin in step 4. It is useful and improves
+   aufs performance when system surely hide the aufs branches from user,
+   by over-mounting something (or another method).
diff --git a/Documentation/filesystems/aufs/design/04branch.txt b/Documentation/filesystems/aufs/design/04branch.txt
new file mode 100644
index 0000000..78432c5
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/04branch.txt
@@ -0,0 +1,67 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+Branch Manipulation
+
+Since aufs supports dynamic branch manipulation, ie. add/remove a branch
+and changing its permission/attribute, there are a lot of works to do.
+
+
+Add a Branch
+----------------------------------------------------------------------
+o Confirm the adding dir exists outside of aufs, including loopback
+  mount.
+- and other various attributes...
+o Initialize the xino file and whiteout bases if necessary.
+  See struct.txt.
+
+o Check the owner/group/mode of the directory
+  When the owner/group/mode of the adding directory differs from the
+  existing branch, aufs issues a warning because it may impose a
+  security risk.
+  For example, when a upper writable branch has a world writable empty
+  top directory, a malicious user can create any files on the writable
+  branch directly, like copy-up and modify manually. If something like
+  /etc/{passwd,shadow} exists on the lower readonly branch but the upper
+  writable branch, and the writable branch is world-writable, then a
+  malicious guy may create /etc/passwd on the writable branch directly
+  and the infected file will be valid in aufs.
+  I am afraid it can be a security issue, but nothing to do except
+  producing a warning.
+
+
+Delete a Branch
+----------------------------------------------------------------------
+o Confirm the deleting branch is not busy
+  To be general, there is one merit to adopt "remount" interface to
+  manipulate branches. It is to discard caches. At deleting a branch,
+  aufs checks the still cached (and connected) dentries and inodes. If
+  there are any, then they are all in-use. An inode without its
+  corresponding dentry can be alive alone (for example, inotify case).
+
+  For the cached one, aufs checks whether the same named entry exists on
+  other branches.
+  If the cached one is a directory, because aufs provides a merged view
+  to users, as long as one dir is left on any branch aufs can show the
+  dir to users. In this case, the branch can be removed from aufs.
+  Otherwise aufs rejects deleting the branch.
+
+  If any file on the deleting branch is opened by aufs, then aufs
+  rejects deleting.
+
+
+Modify the Permission of a Branch
+----------------------------------------------------------------------
+o Re-initialize or remove the xino file and whiteout bases if necessary.
+  See struct.txt.
+
+o rw --> ro: Confirm the modifying branch is not busy
+  Aufs rejects the request if any of these conditions are true.
+  - a file on the branch is mmap-ed.
+  - a regular file on the branch is opened for write and there is no
+    same named entry on the upper branch.
diff --git a/Documentation/filesystems/aufs/design/05wbr_policy.txt b/Documentation/filesystems/aufs/design/05wbr_policy.txt
new file mode 100644
index 0000000..d9720ca
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/05wbr_policy.txt
@@ -0,0 +1,57 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+
+Policies to Select One among Multiple Writable Branches
+----------------------------------------------------------------------
+When the number of writable branch is more than one, aufs has to decide
+the target branch for file creation or copy-up. By default, the highest
+writable branch which has the parent (or ancestor) dir of the target
+file is chosen (top-down-parent policy).
+By user's request, aufs implements some other policies to select the
+writable branch, for file creation two policies, round-robin and
+most-free-space policies. For copy-up three policies, top-down-parent,
+bottom-up-parent and bottom-up policies.
+
+As expected, the round-robin policy selects the branch in circular. When
+you have two writable branches and creates 10 new files, 5 files will be
+created for each branch. mkdir(2) systemcall is an exception. When you
+create 10 new directories, all will be created on the same branch.
+And the most-free-space policy selects the one which has most free
+space among the writable branches. The amount of free space will be
+checked by aufs internally, and users can specify its time interval.
+
+The policies for copy-up is more simple,
+top-down-parent is equivalent to the same named on in create policy,
+bottom-up-parent selects the writable branch where the parent dir
+exists and the nearest upper one from the copyup-source,
+bottom-up selects the nearest upper writable branch from the
+copyup-source, regardless the existence of the parent dir.
+
+There are some rules or exceptions to apply these policies.
+- If there is a readonly branch above the policy-selected branch and
+  the parent dir is marked as opaque (a variation of whiteout), or the
+  target (creating) file is whiteout-ed on the upper readonly branch,
+  then the result of the policy is ignored and the target file will be
+  created on the nearest upper writable branch than the readonly branch.
+- If there is a writable branch above the policy-selected branch and
+  the parent dir is marked as opaque or the target file is whiteouted
+  on the branch, then the result of the policy is ignored and the target
+  file will be created on the highest one among the upper writable
+  branches who has diropq or whiteout. In case of whiteout, aufs removes
+  it as usual.
+- link(2) and rename(2) systemcalls are exceptions in every policy.
+  They try selecting the branch where the source exists as possible
+  since copyup a large file will take long time. If it can't be,
+  ie. the branch where the source exists is readonly, then they will
+  follow the copyup policy.
+- There is an exception for rename(2) when the target exists.
+  If the rename target exists, aufs compares the index of the branches
+  where the source and the target exists and selects the higher
+  one. If the selected branch is readonly, then aufs follows the
+  copyup policy.
diff --git a/Documentation/filesystems/aufs/design/06fmode_exec.txt b/Documentation/filesystems/aufs/design/06fmode_exec.txt
new file mode 100644
index 0000000..b172cd1
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/06fmode_exec.txt
@@ -0,0 +1,24 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+FMODE_EXEC and deny_write()
+----------------------------------------------------------------------
+Generally Unix prevents an executing file from writing its filedata.
+In linux it is implemented by deny_write() and allow_write().
+When a file is executed by exec() family, open_exec() (and sys_uselib())
+they opens the file and calls deny_write(). If the file is aufs's virtual
+one, it has no meaning. The file which deny_write() is really necessary
+is the file on a branch. But the FMODE_EXEC flag is not passed to
+->open() operation. So aufs adopt a dirty trick.
+
+- in order to get FMODE_EXEC, aufs ->lookup() and ->d_revalidate() set
+  nd->intent.open.file->private_data to nd->intent.open.flags temporary.
+- in aufs ->open(), when FMODE_EXEC is set in file->private_data, it
+  calls deny_write() for the file on a branch.
+- when the aufs file is released, allow_write() for the file on a branch
+  is called.
diff --git a/Documentation/filesystems/aufs/design/07mmap.txt b/Documentation/filesystems/aufs/design/07mmap.txt
new file mode 100644
index 0000000..d751c42
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/07mmap.txt
@@ -0,0 +1,44 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+mmap(2) -- File Memory Mapping
+----------------------------------------------------------------------
+In aufs, the file-mapped pages are shared between the file on a branch
+and the virtual one in aufs by overriding vm_operation, particularly
+->fault().
+
+In aufs_mmap(),
+- get and store vm_ops of the real file on a branch.
+- map the file of aufs by generic_file_mmap() and set aufs's vm
+  operations.
+
+In aufs_fault(),
+- get the file of aufs from the passed vma, sleep if needed.
+- get the real file on a branch from the aufs file.
+- a race may happen. for instance a multithreaded library. so some lock
+  is implemented.
+- call ->fault() in the previously stored vm_ops with setting the
+  real file on a branch to vm_file.
+- restore vm_file and wake_up if someone else got sleep.
+
+When a branch is added to or deleted from aufs, the same-named file may
+unveil and its contents will be replaced by the new one when a process
+read(2) through previously opened file.
+(Some users may not want to refresh the filedata. For such users, I
+have a plan to implement a mount option 'refrof' which decides to
+refresh the opened files or not. See plan.txt too.)
+In this case, an already mapped file will not be updated since the
+contents are a part of a process already and it should not be changed by
+aufs branch manipulation. (Even if MAP_SHARED is specified, currently).
+Of course, in case of the deleting branch has a busy file, it cannot be
+deleted from the union.
+
+In Unionfs, it took an approach which the memory pages mapped to
+filedata are copied from the lower (real) file into the Unionfs's
+virtual one and handles it by address_space operations. Recently Unionfs
+changed it to this approach which aufs adopted since Jul 2006.
diff --git a/Documentation/filesystems/aufs/design/08export.txt b/Documentation/filesystems/aufs/design/08export.txt
new file mode 100644
index 0000000..8a7b9e5
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/08export.txt
@@ -0,0 +1,51 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+
+Export Aufs via NFS
+----------------------------------------------------------------------
+Here is an approach.
+- like xino/xib, add a new file 'xigen' which stores aufs inode
+  generation.
+- iget_locked(): initialize aufs inode generation for a new inode, and
+  store it in xigen file.
+- destroy_inode(): increment aufs inode generation and store it in xigen
+  file. it is necessary even if it is not unlinked, because any data of
+  inode may be changed by UDBA.
+- encode_fh(): for a root dir, simply return FILEID_ROOT. otherwise
+  build file handle by
+  + branch id (4 bytes)
+  + superblock generation (4 bytes)
+  + inode number (4 or 8 bytes)
+  + parent dir inode number (4 or 8 bytes)
+  + inode generation (4 bytes))
+  + return value of exportfs_encode_fh() for the parent on a branch (4
+    bytes)
+  + file handle for a branch (by exportfs_encode_fh())
+- fh_to_dentry():
+  + find the index of a branch from its id in handle, and check it is
+    still exist in aufs.
+  + 1st level: get the inode number from handle and search it in cache.
+  + 2nd level: if not found, get the parent inode number from handle and
+    search it in cache. and then open the parent dir, find the matching
+    inode number by vfs_readdir() and get its name, and call
+    lookup_one_len() for the target dentry.
+  + 3rd level: if the parent dir is not cached, call
+    exportfs_decode_fh() for a branch and get the parent on a branch,
+    build a pathname of it, convert it a pathname in aufs, call
+    path_lookup(). now aufs gets a parent dir dentry, then handle it as
+    the 2nd level.
+  + to open the dir, aufs needs struct vfsmount. aufs keeps vfsmount
+    for every branch, but not itself. to get this, (currently) aufs
+    searches in current->nsproxy->mnt_ns list. it may not be a good
+    idea, but I didn't get other approach.
+  + test the generation of the gotten inode.
+- every inode operation: they may get EBUSY due to UDBA. in this case,
+  convert it into ESTALE for NFSD.
+- readdir(): call lockdep_on/off() because filldir in NFSD calls
+  lookup_one_len(), vfs_getattr(), encode_fh() and others.
diff --git a/Documentation/filesystems/aufs/design/99plan.txt b/Documentation/filesystems/aufs/design/99plan.txt
new file mode 100644
index 0000000..3167d0e
--- /dev/null
+++ b/Documentation/filesystems/aufs/design/99plan.txt
@@ -0,0 +1,125 @@
+
+# Copyright (C) 2005-2009 Junjiro R. Okajima
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+Plan
+
+Restoring some features which was implemented in aufs1.
+They were dropped in aufs2 in order to make source files simpler and
+easier to be reviewed.
+
+
+Test Only the Highest One for the Directory Permission (dirperm1 option)
+----------------------------------------------------------------------
+Let's try case study.
+- aufs has two branches, upper readwrite and lower readonly.
+  /au = /rw + /ro
+- "dirA" exists under /ro, but /rw. and its mode is 0700.
+- user invoked "chmod a+rx /au/dirA"
+- then "dirA" becomes world readable?
+
+In this case, /ro/dirA is still 0700 since it exists in readonly branch,
+or it may be a natively readonly filesystem. If aufs respects the lower
+branch, it should not respond readdir request from other users. But user
+allowed it by chmod. Should really aufs rejects showing the entries
+under /ro/dirA?
+
+To be honest, I don't have a best solution for this case. So I
+implemented 'dirperm1' and 'nodirperm1' option in aufs1, and leave it to
+users.
+When dirperm1 is specified, aufs checks only the highest one for the
+directory permission, and shows the entries. Otherwise, as usual, checks
+every dir existing on all branches and rejects the request.
+
+As a side effect, dirperm1 option improves the performance of aufs
+because the number of permission check is reduced.
+
+
+Show Whiteout Mode (shwh)
+----------------------------------------------------------------------
+Generally aufs hides the name of whiteouts. But in some cases, to show
+them is very useful for users. For instance, creating a new middle layer
+(branch) by merging existing layers.
+
+(borrowing aufs1 HOW-TO from a user, Michael Towers)
+When you have three branches,
+- Bottom: 'system', squashfs (underlying base system), read-only
+- Middle: 'mods', squashfs, read-only
+- Top: 'overlay', ram (tmpfs), read-write
+
+The top layer is loaded at boot time and saved at shutdown, to preserve
+the changes made to the system during the session.
+When larger changes have been made, or smaller changes have accumulated,
+the size of the saved top layer data grows. At this point, it would be
+nice to be able to merge the two overlay branches ('mods' and 'overlay')
+and rewrite the 'mods' squashfs, clearing the top layer and thus
+restoring save and load speed.
+
+This merging is simplified by the use of another aufs mount, of just the
+two overlay branches using the 'shwh' option.
+# mount -t aufs -o ro,shwh,br:/livesys/overlay=ro+wh:/livesys/mods=rr+wh \
+       aufs /livesys/merge_union
+
+A merged view of these two branches is then available at
+/livesys/merge_union, and the new feature is that the whiteouts are
+visible!
+Note that in 'shwh' mode the aufs mount must be 'ro', which will disable
+writing to all branches. Also the default mode for all branches is 'ro'.
+It is now possible to save the combined contents of the two overlay
+branches to a new squashfs, e.g.:
+# mksquashfs /livesys/merge_union /path/to/newmods.squash
+
+This new squashfs archive can be stored on the boot device and the
+initramfs will use it to replace the old one at the next boot.
+
+
+Being Another Aufs's Readonly Branch (robr)
+----------------------------------------------------------------------
+Aufs1 allows aufs to be another aufs's readonly branch.
+This feature was developed by a user's request. But it may not be used
+currecnly.
+
+
+Copy-up on Open (coo=)
+----------------------------------------------------------------------
+By default the internal copy-up is executed when it is really necessary.
+It is not done when a file is opened for writing, but when write(2) is
+done. Users who have many (over 100) branches want to know and analyse
+when and what file is copied-up. To insert a new upper branch which
+contains such files only may improve the performance of aufs.
+
+Aufs1 implemented "coo=none | leaf | all" option.
+
+
+Refresh the Opened File (refrof)
+----------------------------------------------------------------------
+This option is implemented in aufs1 but incomplete.
+
+When user reads from a file, he expects to get its latest filedata
+generally. If the file is removed and a new same named file is created,
+the content he gets is unchanged, ie. the unlinked filedata.
+
+Let's try case study again.
+- aufs has two branches.
+  /au = /rw + /ro
+- "fileA" exists under /ro, but /rw.
+- user opened "/au/fileA".
+- he or someone else inserts a branch (/new) between /rw and /ro.
+  /au = /rw + /new + /ro
+- the new branch has "fileA".
+- user reads from the opened "fileA"
+- which filedata should aufs return, from /ro or /new?
+
+Some people says it has to be "from /ro" and it is a semantics of Unix.
+The others say it should be "from /new" because the file is not removed
+and it is equivalent to the case of someone else modifies the file.
+
+Here again I don't have a best and final answer. I got an idea to
+implement 'refrof' and 'norefrof' option. When 'refrof' (REFResh the
+Opened File) is specified (by default), aufs returns the filedata from
+/new.
+Otherwise from /new.
diff --git a/fs/Kconfig b/fs/Kconfig
index 93945dd..75156dd 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -222,6 +222,7 @@ source "fs/qnx4/Kconfig"
 source "fs/romfs/Kconfig"
 source "fs/sysv/Kconfig"
 source "fs/ufs/Kconfig"
+source "fs/aufs/Kconfig"
 
 endif # MISC_FILESYSTEMS
 
diff --git a/fs/Makefile b/fs/Makefile
index dc20db3..a4e9a65 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -124,3 +124,4 @@ obj-$(CONFIG_DEBUG_FS)              += debugfs/
 obj-$(CONFIG_OCFS2_FS)         += ocfs2/
 obj-$(CONFIG_BTRFS_FS)         += btrfs/
 obj-$(CONFIG_GFS2_FS)           += gfs2/
+obj-$(CONFIG_AUFS_FS)           += aufs/
diff --git a/fs/aufs/Kconfig b/fs/aufs/Kconfig
new file mode 100644
index 0000000..04b2060
--- /dev/null
+++ b/fs/aufs/Kconfig
@@ -0,0 +1,109 @@
+config AUFS_FS
+       bool "Aufs (Advanced multi layered unification filesystem) support"
+       depends on EXPERIMENTAL
+       help
+       Aufs is a stackable unification filesystem such as Unionfs,
+       which unifies several directories and provides a merged single
+       directory.
+       In the early days, aufs was entirely re-designed and
+       re-implemented Unionfs Version 1.x series. Introducing many
+       original ideas, approaches and improvements, it becomes totally
+       different from Unionfs while keeping the basic features.
+
+if AUFS_FS
+choice
+       prompt "Maximum number of branches"
+       default AUFS_BRANCH_MAX_127
+       help
+       Specifies the maximum number of branches (or member directories)
+       in a single aufs. The larger value consumes more system
+       resources and has a minor impact to performance.
+config AUFS_BRANCH_MAX_127
+       bool "127"
+       help
+       Specifies the maximum number of branches (or member directories)
+       in a single aufs. The larger value consumes more system
+       resources and has a minor impact to performance.
+config AUFS_BRANCH_MAX_511
+       bool "511"
+       help
+       Specifies the maximum number of branches (or member directories)
+       in a single aufs. The larger value consumes more system
+       resources and has a minor impact to performance.
+config AUFS_BRANCH_MAX_1023
+       bool "1023"
+       help
+       Specifies the maximum number of branches (or member directories)
+       in a single aufs. The larger value consumes more system
+       resources and has a minor impact to performance.
+config AUFS_BRANCH_MAX_32767
+       bool "32767"
+       help
+       Specifies the maximum number of branches (or member directories)
+       in a single aufs. The larger value consumes more system
+       resources and has a minor impact to performance.
+endchoice
+
+config AUFS_HINOTIFY
+       bool "Use inotify to detect actions on a branch"
+       depends on INOTIFY
+       help
+       If you want to modify files on branches directly, eg. bypassing aufs,
+       and want aufs to detect the changes of them fully, then enable this
+       option and use 'udba=inotify' mount option.
+       It will have a negative impact to the performance.
+       See detail in aufs.5.
+
+config AUFS_EXPORT
+       bool "NFS-exportable aufs"
+       depends on EXPORTFS = y
+       help
+       If you want to export your mounted aufs via NFS, then enable this
+       option. There are several requirements for this configuration.
+       See detail in aufs.5.
+
+config AUFS_BR_RAMFS
+       bool "Ramfs (initramfs/rootfs) as an aufs branch"
+       help
+       If you want to use ramfs as an aufs branch fs, then enable this
+       option. Generally tmpfs is recommended.
+       Aufs prohibited them to be a branch fs by default, because
+       initramfs becomes unusable after switch_root or something
+       generally. If you sets initramfs as an aufs branch and boot your
+       system by switch_root, you will meet a problem easily since the
+       files in initramfs may be inaccessible.
+       Unless you are going to use ramfs as an aufs branch fs without
+       switch_root or something, leave it N.
+
+config AUFS_DEBUG
+       bool "Debug aufs"
+       help
+       Enable this to compile aufs internal debug code.
+       It will have a negative impact to the performance.
+
+config AUFS_MAGIC_SYSRQ
+       bool
+       depends on AUFS_DEBUG && MAGIC_SYSRQ
+       default y
+       help
+       Automatic configuration for internal use.
+       When aufs supports Magic SysRq, enabled automatically.
+
+config AUFS_BDEV_LOOP
+       bool
+       depends on BLK_DEV_LOOP
+       default y
+       help
+       Automatic configuration for internal use.
+       Convert =[ym] into =y.
+
+config AUFS_INO_T_64
+       bool
+       depends on AUFS_EXPORT
+       depends on 64BIT && !(ALPHA || S390)
+       default y
+       help
+       Automatic configuration for internal use.
+       /* typedef unsigned long/int __kernel_ino_t */
+       /* alpha and s390x are int */
+endif
diff --git a/fs/aufs/Makefile b/fs/aufs/Makefile
new file mode 100644
index 0000000..477d245
--- /dev/null
+++ b/fs/aufs/Makefile
@@ -0,0 +1,21 @@
+
+include ${srctree}/${src}/magic.mk
+
+obj-$(CONFIG_AUFS_FS) += aufs.o
+aufs-y := module.o sbinfo.o super.o branch.o xino.o sysaufs.o opts.o \
+       wkq.o vfsub.o dcsub.o \
+       cpup.o whout.o plink.o wbr_policy.o \
+       dinfo.o dentry.o \
+       finfo.o file.o f_op.o \
+       dir.o vdir.o \
+       iinfo.o inode.o i_op.o i_op_add.o i_op_del.o i_op_ren.o \
+       ioctl.o
+
+# all are boolean
+aufs-$(CONFIG_SYSFS) += sysfs.o
+aufs-$(CONFIG_DEBUG_FS) += dbgaufs.o
+aufs-$(CONFIG_AUFS_BDEV_LOOP) += loop.o
+aufs-$(CONFIG_AUFS_HINOTIFY) += hinotify.o
+aufs-$(CONFIG_AUFS_EXPORT) += export.o
+aufs-$(CONFIG_AUFS_DEBUG) += debug.o
+aufs-$(CONFIG_AUFS_MAGIC_SYSRQ) += sysrq.o
diff --git a/fs/aufs/aufs.h b/fs/aufs/aufs.h
new file mode 100644
index 0000000..132e84e
--- /dev/null
+++ b/fs/aufs/aufs.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * all header files
+ */
+
+#ifndef __AUFS_H__
+#define __AUFS_H__
+
+#ifdef __KERNEL__
+
+#include <linux/bug.h>
+
+#include "debug.h"
+
+#include "branch.h"
+#include "cpup.h"
+#include "dcsub.h"
+#include "dbgaufs.h"
+#include "dentry.h"
+#include "dir.h"
+#include "file.h"
+#include "fstype.h"
+#include "inode.h"
+#include "loop.h"
+#include "module.h"
+#include "opts.h"
+#include "rwsem.h"
+#include "spl.h"
+#include "super.h"
+#include "sysaufs.h"
+#include "vfsub.h"
+#include "whout.h"
+#include "wkq.h"
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_H__ */
diff --git a/fs/aufs/branch.c b/fs/aufs/branch.c
new file mode 100644
index 0000000..7ef8a18
--- /dev/null
+++ b/fs/aufs/branch.c
@@ -0,0 +1,946 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * branch management
+ */
+
+#include "aufs.h"
+
+/*
+ * free a single branch
+ */
+static void au_br_do_free(struct au_branch *br)
+{
+       int i;
+       struct au_wbr *wbr;
+
+       if (br->br_xino.xi_file)
+               fput(br->br_xino.xi_file);
+       mutex_destroy(&br->br_xino.xi_nondir_mtx);
+
+       AuDebugOn(atomic_read(&br->br_count));
+
+       wbr = br->br_wbr;
+       if (wbr) {
+               for (i = 0; i < AuBrWh_Last; i++)
+                       dput(wbr->wbr_wh[i]);
+               AuDebugOn(atomic_read(&wbr->wbr_wh_running));
+               au_rwsem_destroy(&wbr->wbr_wh_rwsem);
+       }
+
+       /* some filesystems acquire extra lock */
+       lockdep_off();
+       mntput(br->br_mnt);
+       lockdep_on();
+
+       kfree(wbr);
+       kfree(br);
+}
+
+/*
+ * frees all branches
+ */
+void au_br_free(struct au_sbinfo *sbinfo)
+{
+       aufs_bindex_t bmax;
+       struct au_branch **br;
+
+       bmax = sbinfo->si_bend + 1;
+       br = sbinfo->si_branch;
+       while (bmax--)
+               au_br_do_free(*br++);
+}
+
+/*
+ * find the index of a branch which is specified by @br_id.
+ */
+int au_br_index(struct super_block *sb, aufs_bindex_t br_id)
+{
+       aufs_bindex_t bindex, bend;
+
+       bend = au_sbend(sb);
+       for (bindex = 0; bindex <= bend; bindex++)
+               if (au_sbr_id(sb, bindex) == br_id)
+                       return bindex;
+       return -1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * add a branch
+ */
+
+static int test_overlap(struct super_block *sb, struct dentry *h_d1,
+                       struct dentry *h_d2)
+{
+       if (unlikely(h_d1 == h_d2))
+               return 1;
+       return !!au_test_subdir(h_d1, h_d2)
+               || !!au_test_subdir(h_d2, h_d1)
+               || au_test_loopback_overlap(sb, h_d1, h_d2)
+               || au_test_loopback_overlap(sb, h_d2, h_d1);
+}
+
+/*
+ * returns a newly allocated branch. @new_nbranch is a number of branches
+ * after adding a branch.
+ */
+static struct au_branch *au_br_alloc(struct super_block *sb, int new_nbranch,
+                                    int perm)
+{
+       struct au_branch *add_branch;
+       struct dentry *root;
+
+       root = sb->s_root;
+       add_branch = kmalloc(sizeof(*add_branch), GFP_NOFS);
+       if (unlikely(!add_branch))
+               goto out;
+
+       add_branch->br_wbr = NULL;
+       if (au_br_writable(perm)) {
+               /* may be freed separately at changing the branch permission */
+               add_branch->br_wbr = kmalloc(sizeof(*add_branch->br_wbr),
+                                            GFP_NOFS);
+               if (unlikely(!add_branch->br_wbr))
+                       goto out_br;
+       }
+
+       if (unlikely(au_sbr_realloc(au_sbi(sb), new_nbranch)
+                    || au_di_realloc(au_di(root), new_nbranch)
+                    || au_ii_realloc(au_ii(root->d_inode), new_nbranch)))
+               goto out_wbr;
+       return add_branch; /* success */
+
+ out_wbr:
+       kfree(add_branch->br_wbr);
+ out_br:
+       kfree(add_branch);
+ out:
+       return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * test if the branch permission is legal or not.
+ */
+static int test_br(struct inode *inode, int brperm, char *path)
+{
+       int err;
+
+       err = 0;
+       if (unlikely(au_br_writable(brperm) && IS_RDONLY(inode))) {
+               AuErr("write permission for readonly mount or inode, %s\n",
+                     path);
+               err = -EINVAL;
+       }
+
+       return err;
+}
+
+/*
+ * returns:
+ * 0: success, the caller will add it
+ * plus: success, it is already unified, the caller should ignore it
+ * minus: error
+ */
+static int test_add(struct super_block *sb, struct au_opt_add *add, int remount)
+{
+       int err;
+       aufs_bindex_t bend, bindex;
+       struct dentry *root;
+       struct inode *inode, *h_inode;
+
+       root = sb->s_root;
+       bend = au_sbend(sb);
+       if (unlikely(bend >= 0
+                    && au_find_dbindex(root, add->path.dentry) >= 0)) {
+               err = 1;
+               if (!remount) {
+                       err = -EINVAL;
+                       AuErr("%s duplicated\n", add->pathname);
+               }
+               goto out;
+       }
+
+       err = -ENOSPC; /* -E2BIG; */
+       if (unlikely(AUFS_BRANCH_MAX <= add->bindex
+                    || AUFS_BRANCH_MAX - 1 <= bend)) {
+               AuErr("number of branches exceeded %s\n", add->pathname);
+               goto out;
+       }
+
+       err = -EDOM;
+       if (unlikely(add->bindex < 0 || bend + 1 < add->bindex)) {
+               AuErr("bad index %d\n", add->bindex);
+               goto out;
+       }
+
+       inode = add->path.dentry->d_inode;
+       err = -ENOENT;
+       if (unlikely(!inode->i_nlink)) {
+               AuErr("no existence %s\n", add->pathname);
+               goto out;
+       }
+
+       err = -EINVAL;
+       if (unlikely(inode->i_sb == sb)) {
+               AuErr("%s must be outside\n", add->pathname);
+               goto out;
+       }
+
+       if (unlikely(au_test_fs_unsuppoted(inode->i_sb))) {
+               AuErr("unsupported filesystem, %s (%s)\n",
+                     add->pathname, au_sbtype(inode->i_sb));
+               goto out;
+       }
+
+       err = test_br(add->path.dentry->d_inode, add->perm, add->pathname);
+       if (unlikely(err))
+               goto out;
+
+       if (bend < 0)
+               return 0; /* success */
+
+       err = -EINVAL;
+       for (bindex = 0; bindex <= bend; bindex++)
+               if (unlikely(test_overlap(sb, add->path.dentry,
+                                         au_h_dptr(root, bindex)))) {
+                       AuErr("%s is overlapped\n", add->pathname);
+                       goto out;
+               }
+
+       err = 0;
+       if (au_opt_test(au_mntflags(sb), WARN_PERM)) {
+               h_inode = au_h_dptr(root, 0)->d_inode;
+               if ((h_inode->i_mode & S_IALLUGO) != (inode->i_mode & S_IALLUGO)
+                   || h_inode->i_uid != inode->i_uid
+                   || h_inode->i_gid != inode->i_gid)
+                       AuWarn("uid/gid/perm %s %u/%u/0%o, %u/%u/0%o\n",
+                              add->pathname,
+                              inode->i_uid, inode->i_gid,
+                              (inode->i_mode & S_IALLUGO),
+                              h_inode->i_uid, h_inode->i_gid,
+                              (h_inode->i_mode & S_IALLUGO));
+       }
+
+ out:
+       return err;
+}
+
+/*
+ * initialize or clean the whiteouts for an adding branch
+ */
+static int au_br_init_wh(struct super_block *sb, struct au_branch *br,
+                        int new_perm, struct dentry *h_root)
+{
+       int err, old_perm;
+       aufs_bindex_t bindex;
+       struct mutex *h_mtx;
+       struct au_wbr *wbr;
+       struct au_hinode *hdir;
+
+       wbr = br->br_wbr;
+       old_perm = br->br_perm;
+       br->br_perm = new_perm;
+       hdir = NULL;
+       h_mtx = NULL;
+       bindex = au_br_index(sb, br->br_id);
+       if (0 <= bindex) {
+               hdir = au_hi(sb->s_root->d_inode, bindex);
+               au_hin_imtx_lock_nested(hdir, AuLsc_I_PARENT);
+       } else {
+               h_mtx = &h_root->d_inode->i_mutex;
+               mutex_lock_nested(h_mtx, AuLsc_I_PARENT);
+       }
+       if (!wbr)
+               err = au_wh_init(h_root, br, sb);
+       else {
+               wbr_wh_write_lock(wbr);
+               err = au_wh_init(h_root, br, sb);
+               wbr_wh_write_unlock(wbr);
+       }
+       if (hdir)
+               au_hin_imtx_unlock(hdir);
+       else
+               mutex_unlock(h_mtx);
+       br->br_perm = old_perm;
+
+       if (!err && wbr && !au_br_writable(new_perm)) {
+               kfree(wbr);
+               br->br_wbr = NULL;
+       }
+
+       return err;
+}
+
+static int au_wbr_init(struct au_branch *br, struct super_block *sb,
+                      int perm, struct path *path)
+{
+       int err;
+       struct au_wbr *wbr;
+
+       wbr = br->br_wbr;
+       init_rwsem(&wbr->wbr_wh_rwsem);
+       memset(wbr->wbr_wh, 0, sizeof(wbr->wbr_wh));
+       atomic_set(&wbr->wbr_wh_running, 0);
+       wbr->wbr_bytes = 0;
+
+       err = au_br_init_wh(sb, br, perm, path->dentry);
+
+       return err;
+}
+
+/* intialize a new branch */
+static int au_br_init(struct au_branch *br, struct super_block *sb,
+                     struct au_opt_add *add)
+{
+       int err;
+
+       err = 0;
+       memset(&br->br_xino, 0, sizeof(br->br_xino));
+       mutex_init(&br->br_xino.xi_nondir_mtx);
+       br->br_perm = add->perm;
+       br->br_mnt = add->path.mnt; /* set first, mntget() later */
+       atomic_set(&br->br_count, 0);
+       br->br_xino_upper = AUFS_XINO_TRUNC_INIT;
+       atomic_set(&br->br_xino_running, 0);
+       br->br_id = au_new_br_id(sb);
+
+       if (au_br_writable(add->perm)) {
+               err = au_wbr_init(br, sb, add->perm, &add->path);
+               if (unlikely(err))
+                       goto out;
+       }
+
+       if (au_opt_test(au_mntflags(sb), XINO)) {
+               err = au_xino_br(sb, br, add->path.dentry->d_inode->i_ino,
+                                au_sbr(sb, 0)->br_xino.xi_file, /*do_test*/1);
+               if (unlikely(err)) {
+                       AuDebugOn(br->br_xino.xi_file);
+                       goto out;
+               }
+       }
+
+       sysaufs_br_init(br);
+       mntget(add->path.mnt);
+
+ out:
+       return err;
+}
+
+static void au_br_do_add_brp(struct au_sbinfo *sbinfo, aufs_bindex_t bindex,
+                            struct au_branch *br, aufs_bindex_t bend,
+                            aufs_bindex_t amount)
+{
+       struct au_branch **brp;
+
+       brp = sbinfo->si_branch + bindex;
+       memmove(brp + 1, brp, sizeof(*brp) * amount);
+       *brp = br;
+       sbinfo->si_bend++;
+       if (unlikely(bend < 0))
+               sbinfo->si_bend = 0;
+}
+
+static void au_br_do_add_hdp(struct au_dinfo *dinfo, aufs_bindex_t bindex,
+                            aufs_bindex_t bend, aufs_bindex_t amount)
+{
+       struct au_hdentry *hdp;
+
+       hdp = dinfo->di_hdentry + bindex;
+       memmove(hdp + 1, hdp, sizeof(*hdp) * amount);
+       au_h_dentry_init(hdp);
+       dinfo->di_bend++;
+       if (unlikely(bend < 0))
+               dinfo->di_bstart = 0;
+}
+
+static void au_br_do_add_hip(struct au_iinfo *iinfo, aufs_bindex_t bindex,
+                            aufs_bindex_t bend, aufs_bindex_t amount)
+{
+       struct au_hinode *hip;
+
+       hip = iinfo->ii_hinode + bindex;
+       memmove(hip + 1, hip, sizeof(*hip) * amount);
+       hip->hi_inode = NULL;
+       au_hin_init(hip, NULL);
+       iinfo->ii_bend++;
+       if (unlikely(bend < 0))
+               iinfo->ii_bstart = 0;
+}
+
+static void au_br_do_add(struct super_block *sb, struct dentry *h_dentry,
+                        struct au_branch *br, aufs_bindex_t bindex)
+{
+       struct dentry *root;
+       struct inode *root_inode;
+       aufs_bindex_t bend, amount;
+
+       root = sb->s_root;
+       root_inode = root->d_inode;
+       au_plink_block_maintain(sb);
+       bend = au_sbend(sb);
+       amount = bend + 1 - bindex;
+       au_br_do_add_brp(au_sbi(sb), bindex, br, bend, amount);
+       au_br_do_add_hdp(au_di(root), bindex, bend, amount);
+       au_br_do_add_hip(au_ii(root_inode), bindex, bend, amount);
+       au_set_h_dptr(root, bindex, dget(h_dentry));
+       au_set_h_iptr(root_inode, bindex, au_igrab(h_dentry->d_inode),
+                     /*flags*/0);
+}
+
+int au_br_add(struct super_block *sb, struct au_opt_add *add, int remount)
+{
+       int err;
+       unsigned long long maxb;
+       aufs_bindex_t bend, add_bindex;
+       struct dentry *root, *h_dentry;
+       struct inode *root_inode;
+       struct au_branch *add_branch;
+
+       root = sb->s_root;
+       root_inode = root->d_inode;
+       IMustLock(root_inode);
+       err = test_add(sb, add, remount);
+       if (unlikely(err < 0))
+               goto out;
+       if (err) {
+               err = 0;
+               goto out; /* success */
+       }
+
+       bend = au_sbend(sb);
+       add_branch = au_br_alloc(sb, bend + 2, add->perm);
+       err = PTR_ERR(add_branch);
+       if (IS_ERR(add_branch))
+               goto out;
+
+       err = au_br_init(add_branch, sb, add);
+       if (unlikely(err)) {
+               au_br_do_free(add_branch);
+               goto out;
+       }
+
+       add_bindex = add->bindex;
+       h_dentry = add->path.dentry;
+       if (!remount)
+               au_br_do_add(sb, h_dentry, add_branch, add_bindex);
+       else {
+               sysaufs_brs_del(sb, add_bindex);
+               au_br_do_add(sb, h_dentry, add_branch, add_bindex);
+               sysaufs_brs_add(sb, add_bindex);
+       }
+
+       if (!add_bindex)
+               au_cpup_attr_all(root_inode, /*force*/1);
+       else
+               au_add_nlink(root_inode, h_dentry->d_inode);
+       maxb = h_dentry->d_sb->s_maxbytes;
+       if (sb->s_maxbytes < maxb)
+               sb->s_maxbytes = maxb;
+
+       /*
+        * this test/set prevents aufs from handling unnecesary inotify events
+        * of xino files, in a case of re-adding a writable branch which was
+        * once detached from aufs.
+        */
+       if (au_xino_brid(sb) < 0
+           && au_br_writable(add_branch->br_perm)
+           && !au_test_fs_bad_xino(h_dentry->d_sb)
+           && add_branch->br_xino.xi_file
+           && add_branch->br_xino.xi_file->f_dentry->d_parent == h_dentry)
+               au_xino_brid_set(sb, add_branch->br_id);
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * delete a branch
+ */
+
+/* to show the line number, do not make it inlined function */
+#define AuVerbose(do_info, fmt, args...) do { \
+       if (do_info) \
+               AuInfo(fmt, ##args); \
+} while (0)
+
+/*
+ * test if the branch is deletable or not.
+ */
+static int test_dentry_busy(struct dentry *root, aufs_bindex_t bindex,
+                           unsigned int sigen)
+{
+       int err, i, j, ndentry;
+       aufs_bindex_t bstart, bend;
+       unsigned char verbose;
+       struct au_dcsub_pages dpages;
+       struct au_dpage *dpage;
+       struct dentry *d;
+       struct inode *inode;
+
+       err = au_dpages_init(&dpages, GFP_NOFS);
+       if (unlikely(err))
+               goto out;
+       err = au_dcsub_pages(&dpages, root, NULL, NULL);
+       if (unlikely(err))
+               goto out_dpages;
+
+       verbose = !!au_opt_test(au_mntflags(root->d_sb), VERBOSE);
+       for (i = 0; !err && i < dpages.ndpage; i++) {
+               dpage = dpages.dpages + i;
+               ndentry = dpage->ndentry;
+               for (j = 0; !err && j < ndentry; j++) {
+                       d = dpage->dentries[j];
+                       AuDebugOn(!atomic_read(&d->d_count));
+                       inode = d->d_inode;
+                       if (au_digen(d) == sigen && au_iigen(inode) == sigen)
+                               di_read_lock_child(d, AuLock_IR);
+                       else {
+                               di_write_lock_child(d);
+                               err = au_reval_dpath(d, sigen);
+                               if (!err)
+                                       di_downgrade_lock(d, AuLock_IR);
+                               else {
+                                       di_write_unlock(d);
+                                       break;
+                               }
+                       }
+
+                       bstart = au_dbstart(d);
+                       bend = au_dbend(d);
+                       if (bstart <= bindex
+                           && bindex <= bend
+                           && au_h_dptr(d, bindex)
+                           && (!S_ISDIR(inode->i_mode) || bstart == bend)) {
+                               err = -EBUSY;
+                               AuVerbose(verbose, "busy %.*s\n", AuDLNPair(d));
+                       }
+                       di_read_unlock(d, AuLock_IR);
+               }
+       }
+
+ out_dpages:
+       au_dpages_free(&dpages);
+ out:
+       return err;
+}
+
+static int test_inode_busy(struct super_block *sb, aufs_bindex_t bindex,
+                          unsigned int sigen)
+{
+       int err;
+       struct inode *i;
+       aufs_bindex_t bstart, bend;
+       unsigned char verbose;
+
+       err = 0;
+       verbose = !!au_opt_test(au_mntflags(sb), VERBOSE);
+       list_for_each_entry(i, &sb->s_inodes, i_sb_list) {
+               AuDebugOn(!atomic_read(&i->i_count));
+               if (!list_empty(&i->i_dentry))
+                       continue;
+
+               if (au_iigen(i) == sigen)
+                       ii_read_lock_child(i);
+               else {
+                       ii_write_lock_child(i);
+                       err = au_refresh_hinode_self(i, /*do_attr*/1);
+                       if (!err)
+                               ii_downgrade_lock(i);
+                       else {
+                               ii_write_unlock(i);
+                               break;
+                       }
+               }
+
+               bstart = au_ibstart(i);
+               bend = au_ibend(i);
+               if (bstart <= bindex
+                   && bindex <= bend
+                   && au_h_iptr(i, bindex)
+                   && (!S_ISDIR(i->i_mode) || bstart == bend)) {
+                       err = -EBUSY;
+                       AuVerbose(verbose, "busy i%lu\n", i->i_ino);
+                       ii_read_unlock(i);
+                       break;
+               }
+               ii_read_unlock(i);
+       }
+
+       return err;
+}
+
+static int test_children_busy(struct dentry *root, aufs_bindex_t bindex)
+{
+       int err;
+       unsigned int sigen;
+
+       sigen = au_sigen(root->d_sb);
+       DiMustNoWaiters(root);
+       IiMustNoWaiters(root->d_inode);
+       di_write_unlock(root);
+       err = test_dentry_busy(root, bindex, sigen);
+       if (!err)
+               err = test_inode_busy(root->d_sb, bindex, sigen);
+       di_write_lock_child(root); /* aufs_write_lock() calls ..._child() */
+
+       return err;
+}
+
+static void au_br_do_del_brp(struct au_sbinfo *sbinfo,
+                            const aufs_bindex_t bindex,
+                            const aufs_bindex_t bend)
+{
+       struct au_branch **brp, **p;
+
+       brp = sbinfo->si_branch + bindex;
+       if (bindex < bend)
+               memmove(brp, brp + 1, sizeof(*brp) * (bend - bindex));
+       sbinfo->si_branch[0 + bend] = NULL;
+       sbinfo->si_bend--;
+
+       p = krealloc(sbinfo->si_branch, sizeof(*p) * bend, GFP_NOFS);
+       if (p)
+               sbinfo->si_branch = p;
+}
+
+static void au_br_do_del_hdp(struct au_dinfo *dinfo, const aufs_bindex_t bindex,
+                            const aufs_bindex_t bend)
+{
+       struct au_hdentry *hdp, *p;
+
+       hdp = dinfo->di_hdentry + bindex;
+       if (bindex < bend)
+               memmove(hdp, hdp + 1, sizeof(*hdp) * (bend - bindex));
+       dinfo->di_hdentry[0 + bend].hd_dentry = NULL;
+       dinfo->di_bend--;
+
+       p = krealloc(dinfo->di_hdentry, sizeof(*p) * bend, GFP_NOFS);
+       if (p)
+               dinfo->di_hdentry = p;
+}
+
+static void au_br_do_del_hip(struct au_iinfo *iinfo, const aufs_bindex_t bindex,
+                            const aufs_bindex_t bend)
+{
+       struct au_hinode *hip, *p;
+
+       hip = iinfo->ii_hinode + bindex;
+       if (bindex < bend)
+               memmove(hip, hip + 1, sizeof(*hip) * (bend - bindex));
+       iinfo->ii_hinode[0 + bend].hi_inode = NULL;
+       au_hin_init(iinfo->ii_hinode + bend, NULL);
+       iinfo->ii_bend--;
+
+       p = krealloc(iinfo->ii_hinode, sizeof(*p) * bend, GFP_NOFS);
+       if (p)
+               iinfo->ii_hinode = p;
+}
+
+static void au_br_do_del(struct super_block *sb, aufs_bindex_t bindex,
+                        struct au_branch *br)
+{
+       aufs_bindex_t bend;
+       struct au_sbinfo *sbinfo;
+       struct dentry *root;
+       struct inode *inode;
+
+       root = sb->s_root;
+       inode = root->d_inode;
+       au_plink_block_maintain(sb);
+       sbinfo = au_sbi(sb);
+       bend = sbinfo->si_bend;
+
+       dput(au_h_dptr(root, bindex));
+       au_hiput(au_hi(inode, bindex));
+       au_br_do_free(br);
+
+       au_br_do_del_brp(sbinfo, bindex, bend);
+       au_br_do_del_hdp(au_di(root), bindex, bend);
+       au_br_do_del_hip(au_ii(inode), bindex, bend);
+}
+
+int au_br_del(struct super_block *sb, struct au_opt_del *del, int remount)
+{
+       int err, rerr, i;
+       unsigned int mnt_flags;
+       aufs_bindex_t bindex, bend, br_id;
+       unsigned char do_wh, verbose;
+       struct au_branch *br;
+       struct au_wbr *wbr;
+
+       err = 0;
+       bindex = au_find_dbindex(sb->s_root, del->h_path.dentry);
+       if (bindex < 0) {
+               if (remount)
+                       goto out; /* success */
+               err = -ENOENT;
+               AuErr("%s no such branch\n", del->pathname);
+               goto out;
+       }
+       AuDbg("bindex b%d\n", bindex);
+
+       err = -EBUSY;
+       mnt_flags = au_mntflags(sb);
+       verbose = !!au_opt_test(mnt_flags, VERBOSE);
+       bend = au_sbend(sb);
+       if (unlikely(!bend)) {
+               AuVerbose(verbose, "no more branches left\n");
+               goto out;
+       }
+       br = au_sbr(sb, bindex);
+       i = atomic_read(&br->br_count);
+       if (unlikely(i)) {
+               AuVerbose(verbose, "%d file(s) opened\n", i);
+               goto out;
+       }
+
+       wbr = br->br_wbr;
+       do_wh = wbr && (wbr->wbr_whbase || wbr->wbr_plink || wbr->wbr_orph);
+       if (do_wh) {
+               for (i = 0; i < AuBrWh_Last; i++) {
+                       dput(wbr->wbr_wh[i]);
+                       wbr->wbr_wh[i] = NULL;
+               }
+       }
+
+       err = test_children_busy(sb->s_root, bindex);
+       if (unlikely(err)) {
+               if (do_wh)
+                       goto out_wh;
+               goto out;
+       }
+
+       err = 0;
+       br_id = br->br_id;
+       if (!remount)
+               au_br_do_del(sb, bindex, br);
+       else {
+               sysaufs_brs_del(sb, bindex);
+               au_br_do_del(sb, bindex, br);
+               sysaufs_brs_add(sb, bindex);
+       }
+
+       if (!bindex)
+               au_cpup_attr_all(sb->s_root->d_inode, /*force*/1);
+       else
+               au_sub_nlink(sb->s_root->d_inode, del->h_path.dentry->d_inode);
+       if (au_opt_test(mnt_flags, PLINK))
+               au_plink_half_refresh(sb, br_id);
+
+       if (sb->s_maxbytes == del->h_path.dentry->d_sb->s_maxbytes) {
+               bend--;
+               sb->s_maxbytes = 0;
+               for (bindex = 0; bindex <= bend; bindex++) {
+                       unsigned long long maxb;
+
+                       maxb = au_sbr_sb(sb, bindex)->s_maxbytes;
+                       if (sb->s_maxbytes < maxb)
+                               sb->s_maxbytes = maxb;
+               }
+       }
+
+       if (au_xino_brid(sb) == br->br_id)
+               au_xino_brid_set(sb, -1);
+       goto out; /* success */
+
+ out_wh:
+       /* revert */
+       rerr = au_br_init_wh(sb, br, br->br_perm, del->h_path.dentry);
+       if (rerr)
+               AuWarn("failed re-creating base whiteout, %s. (%d)\n",
+                      del->pathname, rerr);
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * change a branch permission
+ */
+
+static int do_need_sigen_inc(int a, int b)
+{
+       return au_br_whable(a) && !au_br_whable(b);
+}
+
+static int need_sigen_inc(int old, int new)
+{
+       return do_need_sigen_inc(old, new)
+               || do_need_sigen_inc(new, old);
+}
+
+static int au_br_mod_files_ro(struct super_block *sb, aufs_bindex_t bindex)
+{
+       int err;
+       unsigned long n, ul, bytes, files;
+       aufs_bindex_t bstart;
+       struct file *file, *hf, **a;
+       const int step_bytes = 1024, /* memory allocation unit */
+               step_files = step_bytes / sizeof(*a);
+
+       err = -ENOMEM;
+       n = 0;
+       bytes = step_bytes;
+       files = step_files;
+       a = kmalloc(bytes, GFP_NOFS);
+       if (unlikely(!a))
+               goto out;
+
+       /* no need file_list_lock() since sbinfo is locked? defered? */
+       list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
+               if (special_file(file->f_dentry->d_inode->i_mode))
+                       continue;
+
+               AuDbg("%.*s\n", AuDLNPair(file->f_dentry));
+               fi_read_lock(file);
+               if (unlikely(au_test_mmapped(file))) {
+                       err = -EBUSY;
+                       FiMustNoWaiters(file);
+                       fi_read_unlock(file);
+                       goto out_free;
+               }
+
+               bstart = au_fbstart(file);
+               if (!S_ISREG(file->f_dentry->d_inode->i_mode)
+                   || !(file->f_mode & FMODE_WRITE)
+                   || bstart != bindex) {
+                       FiMustNoWaiters(file);
+                       fi_read_unlock(file);
+                       continue;
+               }
+
+               hf = au_h_fptr(file, bstart);
+               FiMustNoWaiters(file);
+               fi_read_unlock(file);
+
+               if (n < files)
+                       a[n++] = hf;
+               else {
+                       void *p;
+
+                       err = -ENOMEM;
+                       bytes += step_bytes;
+                       files += step_files;
+                       p = krealloc(a, bytes, GFP_NOFS);
+                       if (p) {
+                               a = p;
+                               a[n++] = hf;
+                       } else
+                               goto out_free;
+               }
+       }
+
+       err = 0;
+       for (ul = 0; ul < n; ul++) {
+               /* todo: already flushed? */
+               /* cf. fs/super.c:mark_files_ro() */
+               hf = a[ul];
+               hf->f_mode &= ~FMODE_WRITE;
+               if (!file_check_writeable(hf)) {
+                       file_release_write(hf);
+                       mnt_drop_write(hf->f_vfsmnt);
+               }
+       }
+
+ out_free:
+       kfree(a);
+ out:
+       return err;
+}
+
+int au_br_mod(struct super_block *sb, struct au_opt_mod *mod, int remount,
+             int *do_update)
+{
+       int err, rerr;
+       aufs_bindex_t bindex;
+       struct dentry *root;
+       struct au_branch *br;
+
+       root = sb->s_root;
+       au_plink_block_maintain(sb);
+       bindex = au_find_dbindex(root, mod->h_root);
+       if (bindex < 0) {
+               if (remount)
+                       return 0; /* success */
+               err = -ENOENT;
+               AuErr("%s no such branch\n", mod->path);
+               goto out;
+       }
+       AuDbg("bindex b%d\n", bindex);
+
+       err = test_br(mod->h_root->d_inode, mod->perm, mod->path);
+       if (unlikely(err))
+               goto out;
+
+       br = au_sbr(sb, bindex);
+       if (br->br_perm == mod->perm)
+               return 0; /* success */
+
+       if (au_br_writable(br->br_perm)) {
+               /* remove whiteout base */
+               err = au_br_init_wh(sb, br, mod->perm, mod->h_root);
+               if (unlikely(err))
+                       goto out;
+
+               if (!au_br_writable(mod->perm)) {
+                       /* rw --> ro, file might be mmapped */
+                       DiMustNoWaiters(root);
+                       IiMustNoWaiters(root->d_inode);
+                       di_write_unlock(root);
+                       err = au_br_mod_files_ro(sb, bindex);
+                       /* aufs_write_lock() calls ..._child() */
+                       di_write_lock_child(root);
+
+                       if (unlikely(err)) {
+                               rerr = -ENOMEM;
+                               br->br_wbr = kmalloc(sizeof(*br->br_wbr),
+                                                    GFP_NOFS);
+                               if (br->br_wbr)
+                                       rerr = au_br_init_wh
+                                               (sb, br, br->br_perm,
+                                                mod->h_root);
+                               if (unlikely(rerr)) {
+                                       AuIOErr("nested error %d (%d)\n",
+                                               rerr, err);
+                                       br->br_perm = mod->perm;
+                               }
+                       }
+               }
+       } else if (au_br_writable(mod->perm)) {
+               /* ro --> rw */
+               err = -ENOMEM;
+               br->br_wbr = kmalloc(sizeof(*br->br_wbr), GFP_NOFS);
+               if (br->br_wbr) {
+                       struct path path = {
+                               .mnt    = br->br_mnt,
+                               .dentry = mod->h_root
+                       };
+
+                       err = au_wbr_init(br, sb, mod->perm, &path);
+                       if (unlikely(err)) {
+                               kfree(br->br_wbr);
+                               br->br_wbr = NULL;
+                       }
+               }
+       }
+
+       if (!err) {
+               *do_update |= need_sigen_inc(br->br_perm, mod->perm);
+               br->br_perm = mod->perm;
+       }
+
+ out:
+       return err;
+}
diff --git a/fs/aufs/branch.h b/fs/aufs/branch.h
new file mode 100644
index 0000000..e448692
--- /dev/null
+++ b/fs/aufs/branch.h
@@ -0,0 +1,207 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * branch filesystems and xino for them
+ */
+
+#ifndef __AUFS_BRANCH_H__
+#define __AUFS_BRANCH_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/sysfs.h>
+#include <linux/aufs_type.h>
+#include "rwsem.h"
+#include "super.h"
+
+/* ---------------------------------------------------------------------- */
+
+/* a xino file */
+struct au_xino_file {
+       struct file             *xi_file;
+       struct mutex            xi_nondir_mtx;
+
+       /* todo: make xino files an array to support huge inode number */
+
+#ifdef CONFIG_DEBUG_FS
+       struct dentry            *xi_dbgaufs;
+#endif
+};
+
+/* members for writable branch only */
+enum {AuBrWh_BASE, AuBrWh_PLINK, AuBrWh_ORPH, AuBrWh_Last};
+struct au_wbr {
+       struct rw_semaphore     wbr_wh_rwsem;
+       struct dentry           *wbr_wh[AuBrWh_Last];
+       atomic_t                wbr_wh_running;
+#define wbr_whbase             wbr_wh[AuBrWh_BASE]     /* whiteout base */
+#define wbr_plink              wbr_wh[AuBrWh_PLINK]    /* pseudo-link dir */
+#define wbr_orph               wbr_wh[AuBrWh_ORPH]     /* dir for orphans */
+
+       /* mfs mode */
+       unsigned long long      wbr_bytes;
+};
+
+/* protected by superblock rwsem */
+struct au_branch {
+       struct au_xino_file     br_xino;
+
+       aufs_bindex_t           br_id;
+
+       int                     br_perm;
+       struct vfsmount         *br_mnt;
+       atomic_t                br_count;
+
+       struct au_wbr           *br_wbr;
+
+       /* xino truncation */
+       blkcnt_t                br_xino_upper;  /* watermark in blocks */
+       atomic_t                br_xino_running;
+
+#ifdef CONFIG_SYSFS
+       /* an entry under sysfs per mount-point */
+       char                    br_name[8];
+       struct attribute        br_attr;
+#endif
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* branch permission and attribute */
+enum {
+       AuBrPerm_RW,            /* writable, linkable wh */
+       AuBrPerm_RO,            /* readonly, no wh */
+       AuBrPerm_RR,            /* natively readonly, no wh */
+
+       AuBrPerm_RWNoLinkWH,    /* un-linkable whiteouts */
+
+       AuBrPerm_ROWH,          /* whiteout-able */
+       AuBrPerm_RRWH,          /* whiteout-able */
+
+       AuBrPerm_Last
+};
+
+static inline int au_br_writable(int brperm)
+{
+       return brperm == AuBrPerm_RW || brperm == AuBrPerm_RWNoLinkWH;
+}
+
+static inline int au_br_whable(int brperm)
+{
+       return brperm == AuBrPerm_RW
+               || brperm == AuBrPerm_ROWH
+               || brperm == AuBrPerm_RRWH;
+}
+
+static inline int au_br_rdonly(struct au_branch *br)
+{
+       return ((br->br_mnt->mnt_sb->s_flags & MS_RDONLY)
+               || !au_br_writable(br->br_perm))
+               ? -EROFS : 0;
+}
+
+static inline int au_br_hinotifyable(int brperm __maybe_unused)
+{
+#ifdef CONFIG_AUFS_HINOTIFY
+       return brperm != AuBrPerm_RR && brperm != AuBrPerm_RRWH;
+#else
+       return 0;
+#endif
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* branch.c */
+struct au_sbinfo;
+void au_br_free(struct au_sbinfo *sinfo);
+int au_br_index(struct super_block *sb, aufs_bindex_t br_id);
+struct au_opt_add;
+int au_br_add(struct super_block *sb, struct au_opt_add *add, int remount);
+struct au_opt_del;
+int au_br_del(struct super_block *sb, struct au_opt_del *del, int remount);
+struct au_opt_mod;
+int au_br_mod(struct super_block *sb, struct au_opt_mod *mod, int remount,
+             int *do_update);
+
+/* xino.c */
+static const loff_t au_loff_max = LLONG_MAX;
+
+int au_xib_trunc(struct super_block *sb);
+ssize_t xino_fread(au_readf_t func, struct file *file, void *buf, size_t size,
+                  loff_t *pos);
+ssize_t xino_fwrite(au_writef_t func, struct file *file, void *buf, size_t size,
+                   loff_t *pos);
+struct file *au_xino_create2(struct file *base_file, struct file *copy_src);
+struct file *au_xino_create(struct super_block *sb, char *fname, int silent);
+ino_t au_xino_new_ino(struct super_block *sb);
+int au_xino_write0(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                  ino_t ino);
+int au_xino_write(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                 ino_t ino);
+int au_xino_read(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                ino_t *ino);
+int au_xino_br(struct super_block *sb, struct au_branch *br, ino_t hino,
+              struct file *base_file, int do_test);
+int au_xino_trunc(struct super_block *sb, aufs_bindex_t bindex);
+
+struct au_opt_xino;
+int au_xino_set(struct super_block *sb, struct au_opt_xino *xino, int remount);
+void au_xino_clr(struct super_block *sb);
+struct file *au_xino_def(struct super_block *sb);
+int au_xino_path(struct seq_file *seq, struct file *file);
+
+/* ---------------------------------------------------------------------- */
+
+/* Superblock to branch */
+static inline
+aufs_bindex_t au_sbr_id(struct super_block *sb, aufs_bindex_t bindex)
+{
+       return au_sbr(sb, bindex)->br_id;
+}
+
+static inline
+struct vfsmount *au_sbr_mnt(struct super_block *sb, aufs_bindex_t bindex)
+{
+       return au_sbr(sb, bindex)->br_mnt;
+}
+
+static inline
+struct super_block *au_sbr_sb(struct super_block *sb, aufs_bindex_t bindex)
+{
+       return au_sbr_mnt(sb, bindex)->mnt_sb;
+}
+
+static inline void au_sbr_put(struct super_block *sb, aufs_bindex_t bindex)
+{
+       atomic_dec(&au_sbr(sb, bindex)->br_count);
+}
+
+static inline int au_sbr_perm(struct super_block *sb, aufs_bindex_t bindex)
+{
+       return au_sbr(sb, bindex)->br_perm;
+}
+
+static inline int au_sbr_whable(struct super_block *sb, aufs_bindex_t bindex)
+{
+       return au_br_whable(au_sbr_perm(sb, bindex));
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * wbr_wh_read_lock, wbr_wh_write_lock
+ * wbr_wh_read_unlock, wbr_wh_write_unlock, wbr_wh_downgrade_lock
+ */
+AuSimpleRwsemFuncs(wbr_wh, struct au_wbr *wbr, &wbr->wbr_wh_rwsem);
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_BRANCH_H__ */
diff --git a/fs/aufs/cpup.c b/fs/aufs/cpup.c
new file mode 100644
index 0000000..91808b1
--- /dev/null
+++ b/fs/aufs/cpup.c
@@ -0,0 +1,1028 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * copy-up functions, see wbr_policy.c for copy-down
+ */
+
+#include <linux/fs_stack.h>
+#include <linux/uaccess.h>
+#include "aufs.h"
+
+void au_cpup_attr_flags(struct inode *dst, struct inode *src)
+{
+       const unsigned int mask = S_DEAD | S_SWAPFILE | S_PRIVATE
+               | S_NOATIME | S_NOCMTIME;
+
+       dst->i_flags |= src->i_flags & ~mask;
+       if (au_test_fs_notime(dst->i_sb))
+               dst->i_flags |= S_NOATIME | S_NOCMTIME;
+}
+
+void au_cpup_attr_timesizes(struct inode *inode)
+{
+       struct inode *h_inode;
+
+       h_inode = au_h_iptr(inode, au_ibstart(inode));
+       fsstack_copy_attr_times(inode, h_inode);
+       vfsub_copy_inode_size(inode, h_inode);
+}
+
+void au_cpup_attr_nlink(struct inode *inode, int force)
+{
+       struct inode *h_inode;
+       struct super_block *sb;
+       aufs_bindex_t bindex, bend;
+
+       sb = inode->i_sb;
+       bindex = au_ibstart(inode);
+       h_inode = au_h_iptr(inode, bindex);
+       if (!force
+           && !S_ISDIR(h_inode->i_mode)
+           && au_opt_test(au_mntflags(sb), PLINK)
+           && au_plink_test(inode))
+               return;
+
+       inode->i_nlink = h_inode->i_nlink;
+
+       /*
+        * fewer nlink makes find(1) noisy, but larger nlink doesn't.
+        * it may includes whplink directory.
+        */
+       if (S_ISDIR(h_inode->i_mode)) {
+               bend = au_ibend(inode);
+               for (bindex++; bindex <= bend; bindex++) {
+                       h_inode = au_h_iptr(inode, bindex);
+                       if (h_inode)
+                               au_add_nlink(inode, h_inode);
+               }
+       }
+}
+
+void au_cpup_attr_changeable(struct inode *inode)
+{
+       struct inode *h_inode;
+
+       h_inode = au_h_iptr(inode, au_ibstart(inode));
+       inode->i_mode = h_inode->i_mode;
+       inode->i_uid = h_inode->i_uid;
+       inode->i_gid = h_inode->i_gid;
+       au_cpup_attr_timesizes(inode);
+       au_cpup_attr_flags(inode, h_inode);
+}
+
+void au_cpup_igen(struct inode *inode, struct inode *h_inode)
+{
+       struct au_iinfo *iinfo = au_ii(inode);
+
+       iinfo->ii_higen = h_inode->i_generation;
+       iinfo->ii_hsb1 = h_inode->i_sb;
+}
+
+void au_cpup_attr_all(struct inode *inode, int force)
+{
+       struct inode *h_inode;
+
+       h_inode = au_h_iptr(inode, au_ibstart(inode));
+       au_cpup_attr_changeable(inode);
+       if (inode->i_nlink > 0)
+               au_cpup_attr_nlink(inode, force);
+       inode->i_rdev = h_inode->i_rdev;
+       inode->i_blkbits = h_inode->i_blkbits;
+       au_cpup_igen(inode, h_inode);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* Note: dt_dentry and dt_h_dentry are not dget/dput-ed */
+
+/* keep the timestamps of the parent dir when cpup */
+void au_dtime_store(struct au_dtime *dt, struct dentry *dentry,
+                   struct path *h_path)
+{
+       struct inode *h_inode;
+
+       dt->dt_dentry = dentry;
+       dt->dt_h_path = *h_path;
+       h_inode = h_path->dentry->d_inode;
+       dt->dt_atime = h_inode->i_atime;
+       dt->dt_mtime = h_inode->i_mtime;
+       /* smp_mb(); */
+}
+
+void au_dtime_revert(struct au_dtime *dt)
+{
+       struct iattr attr;
+       int err;
+
+       attr.ia_atime = dt->dt_atime;
+       attr.ia_mtime = dt->dt_mtime;
+       attr.ia_valid = ATTR_FORCE | ATTR_MTIME | ATTR_MTIME_SET
+               | ATTR_ATIME | ATTR_ATIME_SET;
+
+       err = vfsub_notify_change(&dt->dt_h_path, &attr);
+       if (unlikely(err))
+               AuWarn("restoring timestamps failed(%d). ignored\n", err);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static noinline_for_stack
+int cpup_iattr(struct dentry *dst, aufs_bindex_t bindex, struct dentry *h_src)
+{
+       int err, sbits;
+       struct iattr ia;
+       struct path h_path;
+       struct inode *h_isrc;
+
+       h_path.dentry = au_h_dptr(dst, bindex);
+       h_path.mnt = au_sbr_mnt(dst->d_sb, bindex);
+       h_isrc = h_src->d_inode;
+       ia.ia_valid = ATTR_FORCE | ATTR_MODE | ATTR_UID | ATTR_GID
+               | ATTR_ATIME | ATTR_MTIME
+               | ATTR_ATIME_SET | ATTR_MTIME_SET;
+       ia.ia_mode = h_isrc->i_mode;
+       ia.ia_uid = h_isrc->i_uid;
+       ia.ia_gid = h_isrc->i_gid;
+       ia.ia_atime = h_isrc->i_atime;
+       ia.ia_mtime = h_isrc->i_mtime;
+       sbits = !!(ia.ia_mode & (S_ISUID | S_ISGID));
+       au_cpup_attr_flags(h_path.dentry->d_inode, h_isrc);
+       err = vfsub_notify_change(&h_path, &ia);
+
+       /* is this nfs only? */
+       if (!err && sbits && au_test_nfs(h_path.dentry->d_sb)) {
+               ia.ia_valid = ATTR_FORCE | ATTR_MODE;
+               ia.ia_mode = h_isrc->i_mode;
+               err = vfsub_notify_change(&h_path, &ia);
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_do_copy_file(struct file *dst, struct file *src, loff_t len,
+                          char *buf, unsigned long blksize)
+{
+       int err;
+       size_t sz, rbytes, wbytes;
+       unsigned char all_zero;
+       char *p, *zp;
+       struct mutex *h_mtx;
+       /* reduce stack usage */
+       struct iattr *ia;
+
+       zp = page_address(ZERO_PAGE(0));
+       if (unlikely(!zp))
+               return -ENOMEM; /* possible? */
+
+       err = 0;
+       all_zero = 0;
+       while (len) {
+               AuDbg("len %lld\n", len);
+               sz = blksize;
+               if (len < blksize)
+                       sz = len;
+
+               rbytes = 0;
+               /* todo: signal_pending? */
+               while (!rbytes || err == -EAGAIN || err == -EINTR) {
+                       rbytes = vfsub_read_k(src, buf, sz, &src->f_pos);
+                       err = rbytes;
+               }
+               if (unlikely(err < 0))
+                       break;
+
+               all_zero = 0;
+               if (len >= rbytes && rbytes == blksize)
+                       all_zero = !memcmp(buf, zp, rbytes);
+               if (!all_zero) {
+                       wbytes = rbytes;
+                       p = buf;
+                       while (wbytes) {
+                               size_t b;
+
+                               b = vfsub_write_k(dst, p, wbytes, &dst->f_pos);
+                               err = b;
+                               /* todo: signal_pending? */
+                               if (unlikely(err == -EAGAIN || err == -EINTR))
+                                       continue;
+                               if (unlikely(err < 0))
+                                       break;
+                               wbytes -= b;
+                               p += b;
+                       }
+               } else {
+                       loff_t res;
+
+                       AuLabel(hole);
+                       res = vfsub_llseek(dst, rbytes, SEEK_CUR);
+                       err = res;
+                       if (unlikely(res < 0))
+                               break;
+               }
+               len -= rbytes;
+               err = 0;
+       }
+
+       /* the last block may be a hole */
+       if (!err && all_zero) {
+               AuLabel(last hole);
+
+               err = 1;
+               if (au_test_nfs(dst->f_dentry->d_sb)) {
+                       /* nfs requires this step to make last hole */
+                       /* is this only nfs? */
+                       do {
+                               /* todo: signal_pending? */
+                               err = vfsub_write_k(dst, "\0", 1, &dst->f_pos);
+                       } while (err == -EAGAIN || err == -EINTR);
+                       if (err == 1)
+                               dst->f_pos--;
+               }
+
+               if (err == 1) {
+                       ia = (void *)buf;
+                       ia->ia_size = dst->f_pos;
+                       ia->ia_valid = ATTR_SIZE | ATTR_FILE;
+                       ia->ia_file = dst;
+                       h_mtx = &dst->f_dentry->d_inode->i_mutex;
+                       mutex_lock_nested(h_mtx, AuLsc_I_CHILD2);
+                       err = vfsub_notify_change(&dst->f_path, ia);
+                       mutex_unlock(h_mtx);
+               }
+       }
+
+       return err;
+}
+
+int au_copy_file(struct file *dst, struct file *src, loff_t len)
+{
+       int err;
+       unsigned long blksize;
+       unsigned char do_kfree;
+       char *buf;
+
+       err = -ENOMEM;
+       blksize = dst->f_dentry->d_sb->s_blocksize;
+       if (!blksize || PAGE_SIZE < blksize)
+               blksize = PAGE_SIZE;
+       AuDbg("blksize %lu\n", blksize);
+       do_kfree = (blksize != PAGE_SIZE && blksize >= sizeof(struct iattr *));
+       if (do_kfree)
+               buf = kmalloc(blksize, GFP_NOFS);
+       else
+               buf = (void *)__get_free_page(GFP_NOFS);
+       if (unlikely(!buf))
+               goto out;
+
+       if (len > (1 << 22))
+               AuDbg("copying a large file %lld\n", (long long)len);
+
+       src->f_pos = 0;
+       dst->f_pos = 0;
+       err = au_do_copy_file(dst, src, len, buf, blksize);
+       if (do_kfree)
+               kfree(buf);
+       else
+               free_page((unsigned long)buf);
+
+ out:
+       return err;
+}
+
+/*
+ * to support a sparse file which is opened with O_APPEND,
+ * we need to close the file.
+ */
+static int au_cp_regular(struct dentry *dentry, aufs_bindex_t bdst,
+                       aufs_bindex_t bsrc, loff_t len)
+{
+       int err, i;
+       enum { SRC, DST };
+       struct {
+               aufs_bindex_t bindex;
+               unsigned int flags;
+               struct dentry *dentry;
+               struct file *file;
+               void *label, *label_file;
+       } *f, file[] = {
+               {
+                       .bindex = bsrc,
+                       .flags = O_RDONLY | O_NOATIME | O_LARGEFILE,
+                       .file = NULL,
+                       .label = &&out,
+                       .label_file = &&out_src
+               },
+               {
+                       .bindex = bdst,
+                       .flags = O_WRONLY | O_NOATIME | O_LARGEFILE,
+                       .file = NULL,
+                       .label = &&out_src,
+                       .label_file = &&out_dst
+               }
+       };
+       struct super_block *sb;
+
+       /* bsrc branch can be ro/rw. */
+       sb = dentry->d_sb;
+       f = file;
+       for (i = 0; i < 2; i++, f++) {
+               f->dentry = au_h_dptr(dentry, f->bindex);
+               f->file = au_h_open(dentry, f->bindex, f->flags, /*file*/NULL);
+               err = PTR_ERR(f->file);
+               if (IS_ERR(f->file))
+                       goto *f->label;
+               err = -EINVAL;
+               if (unlikely(!f->file->f_op))
+                       goto *f->label_file;
+       }
+
+       /* try stopping to update while we copyup */
+       IMustLock(file[SRC].dentry->d_inode);
+       err = au_copy_file(file[DST].file, file[SRC].file, len);
+
+ out_dst:
+       fput(file[DST].file);
+       au_sbr_put(sb, file[DST].bindex);
+ out_src:
+       fput(file[SRC].file);
+       au_sbr_put(sb, file[SRC].bindex);
+ out:
+       return err;
+}
+
+static int au_do_cpup_regular(struct dentry *dentry, aufs_bindex_t bdst,
+                             aufs_bindex_t bsrc, loff_t len,
+                             struct inode *h_dir, struct path *h_path)
+{
+       int err, rerr;
+       loff_t l;
+
+       err = 0;
+       l = i_size_read(au_h_iptr(dentry->d_inode, bsrc));
+       if (len == -1 || l < len)
+               len = l;
+       if (len)
+               err = au_cp_regular(dentry, bdst, bsrc, len);
+       if (!err)
+               goto out; /* success */
+
+       rerr = vfsub_unlink(h_dir, h_path, /*force*/0);
+       if (rerr) {
+               AuIOErr("failed unlinking cpup-ed %.*s(%d, %d)\n",
+                       AuDLNPair(h_path->dentry), err, rerr);
+               err = -EIO;
+       }
+
+ out:
+       return err;
+}
+
+static int au_do_cpup_symlink(struct path *h_path, struct dentry *h_src,
+                             struct inode *h_dir)
+{
+       int err, symlen;
+       mm_segment_t old_fs;
+       char *sym;
+
+       err = -ENOSYS;
+       if (unlikely(!h_src->d_inode->i_op->readlink))
+               goto out;
+
+       err = -ENOMEM;
+       sym = __getname();
+       if (unlikely(!sym))
+               goto out;
+
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+       symlen = h_src->d_inode->i_op->readlink(h_src, (char __user *)sym,
+                                               PATH_MAX);
+       err = symlen;
+       set_fs(old_fs);
+
+       if (symlen > 0) {
+               sym[symlen] = 0;
+               err = vfsub_symlink(h_dir, h_path, sym);
+       }
+       __putname(sym);
+
+ out:
+       return err;
+}
+
+/* return with the lower dst inode is locked */
+static noinline_for_stack
+int cpup_entry(struct dentry *dentry, aufs_bindex_t bdst,
+              aufs_bindex_t bsrc, loff_t len, unsigned int flags,
+              struct dentry *dst_parent)
+{
+       int err;
+       umode_t mode;
+       unsigned int mnt_flags;
+       unsigned char isdir;
+       const unsigned char do_dt = !!au_ftest_cpup(flags, DTIME);
+       struct au_dtime dt;
+       struct path h_path;
+       struct dentry *h_src, *h_dst, *h_parent;
+       struct inode *h_inode, *h_dir;
+       struct super_block *sb;
+
+       /* bsrc branch can be ro/rw. */
+       h_src = au_h_dptr(dentry, bsrc);
+       h_inode = h_src->d_inode;
+       AuDebugOn(h_inode != au_h_iptr(dentry->d_inode, bsrc));
+
+       /* try stopping to be referenced while we are creating */
+       h_dst = au_h_dptr(dentry, bdst);
+       h_parent = h_dst->d_parent; /* dir inode is locked */
+       h_dir = h_parent->d_inode;
+       IMustLock(h_dir);
+       AuDebugOn(h_parent != h_dst->d_parent);
+
+       sb = dentry->d_sb;
+       h_path.mnt = au_sbr_mnt(sb, bdst);
+       if (do_dt) {
+               h_path.dentry = h_parent;
+               au_dtime_store(&dt, dst_parent, &h_path);
+       }
+       h_path.dentry = h_dst;
+
+       isdir = 0;
+       mode = h_inode->i_mode;
+       switch (mode & S_IFMT) {
+       case S_IFREG:
+               /* try stopping to update while we are referencing */
+               IMustLock(h_inode);
+               err = vfsub_create(h_dir, &h_path, mode | S_IWUSR);
+               if (!err)
+                       err = au_do_cpup_regular
+                               (dentry, bdst, bsrc, len,
+                                au_h_iptr(dst_parent->d_inode, bdst), &h_path);
+               break;
+       case S_IFDIR:
+               isdir = 1;
+               err = vfsub_mkdir(h_dir, &h_path, mode);
+               if (!err) {
+                       /*
+                        * strange behaviour from the users view,
+                        * particularry setattr case
+                        */
+                       if (au_ibstart(dst_parent->d_inode) == bdst)
+                               au_cpup_attr_nlink(dst_parent->d_inode,
+                                                  /*force*/1);
+                       au_cpup_attr_nlink(dentry->d_inode, /*force*/1);
+               }
+               break;
+       case S_IFLNK:
+               err = au_do_cpup_symlink(&h_path, h_src, h_dir);
+               break;
+       case S_IFCHR:
+       case S_IFBLK:
+               AuDebugOn(!capable(CAP_MKNOD));
+               /*FALLTHROUGH*/
+       case S_IFIFO:
+       case S_IFSOCK:
+               err = vfsub_mknod(h_dir, &h_path, mode, h_inode->i_rdev);
+               break;
+       default:
+               AuIOErr("Unknown inode type 0%o\n", mode);
+               err = -EIO;
+       }
+
+       mnt_flags = au_mntflags(sb);
+       if (!au_opt_test(mnt_flags, UDBA_NONE)
+           && !isdir
+           && au_opt_test(mnt_flags, XINO)
+           && h_inode->i_nlink == 1
+           /* todo: unnecessary? */
+           /* && dentry->d_inode->i_nlink == 1 */
+           && bdst < bsrc
+           && !au_ftest_cpup(flags, KEEPLINO))
+               au_xino_write0(sb, bsrc, h_inode->i_ino, /*ino*/0);
+               /* ignore this error */
+
+       if (do_dt)
+               au_dtime_revert(&dt);
+       return err;
+}
+
+/*
+ * copyup the @dentry from @bsrc to @bdst.
+ * the caller must set the both of lower dentries.
+ * @len is for truncating when it is -1 copyup the entire file.
+ * in link/rename cases, @dst_parent may be different from the real one.
+ */
+static int au_cpup_single(struct dentry *dentry, aufs_bindex_t bdst,
+                         aufs_bindex_t bsrc, loff_t len, unsigned int flags,
+                         struct dentry *dst_parent)
+{
+       int err, rerr;
+       aufs_bindex_t old_ibstart;
+       unsigned char isdir, plink;
+       struct au_dtime dt;
+       struct path h_path;
+       struct dentry *h_src, *h_dst, *h_parent;
+       struct inode *dst_inode, *h_dir, *inode;
+       struct super_block *sb;
+
+       AuDebugOn(bsrc <= bdst);
+
+       sb = dentry->d_sb;
+       h_path.mnt = au_sbr_mnt(sb, bdst);
+       h_dst = au_h_dptr(dentry, bdst);
+       h_parent = h_dst->d_parent; /* dir inode is locked */
+       h_dir = h_parent->d_inode;
+       IMustLock(h_dir);
+
+       h_src = au_h_dptr(dentry, bsrc);
+       inode = dentry->d_inode;
+
+       if (!dst_parent)
+               dst_parent = dget_parent(dentry);
+       else
+               dget(dst_parent);
+
+       plink = !!au_opt_test(au_mntflags(sb), PLINK);
+       dst_inode = au_h_iptr(inode, bdst);
+       if (dst_inode) {
+               if (unlikely(!plink)) {
+                       err = -EIO;
+                       AuIOErr("i%lu exists on a upper branch "
+                               "but plink is disabled\n", inode->i_ino);
+                       goto out;
+               }
+
+               if (dst_inode->i_nlink) {
+                       const int do_dt = au_ftest_cpup(flags, DTIME);
+
+                       h_src = au_plink_lkup(inode, bdst);
+                       err = PTR_ERR(h_src);
+                       if (IS_ERR(h_src))
+                               goto out;
+                       if (unlikely(!h_src->d_inode)) {
+                               err = -EIO;
+                               AuIOErr("i%lu exists on a upper branch "
+                                       "but plink is broken\n", inode->i_ino);
+                               dput(h_src);
+                               goto out;
+                       }
+
+                       if (do_dt) {
+                               h_path.dentry = h_parent;
+                               au_dtime_store(&dt, dst_parent, &h_path);
+                       }
+                       h_path.dentry = h_dst;
+                       err = vfsub_link(h_src, h_dir, &h_path);
+                       if (do_dt)
+                               au_dtime_revert(&dt);
+                       dput(h_src);
+                       goto out;
+               } else
+                       /* todo: cpup_wh_file? */
+                       /* udba work */
+                       au_update_brange(inode, 1);
+       }
+
+       old_ibstart = au_ibstart(inode);
+       err = cpup_entry(dentry, bdst, bsrc, len, flags, dst_parent);
+       if (unlikely(err))
+               goto out;
+       dst_inode = h_dst->d_inode;
+       mutex_lock_nested(&dst_inode->i_mutex, AuLsc_I_CHILD2);
+
+       err = cpup_iattr(dentry, bdst, h_src);
+       isdir = S_ISDIR(dst_inode->i_mode);
+       if (!err) {
+               if (bdst < old_ibstart)
+                       au_set_ibstart(inode, bdst);
+               au_set_h_iptr(inode, bdst, au_igrab(dst_inode),
+                             au_hi_flags(inode, isdir));
+               mutex_unlock(&dst_inode->i_mutex);
+               if (!isdir
+                   && h_src->d_inode->i_nlink > 1
+                   && plink)
+                       au_plink_append(inode, bdst, h_dst);
+               goto out; /* success */
+       }
+
+       /* revert */
+       h_path.dentry = h_parent;
+       mutex_unlock(&dst_inode->i_mutex);
+       au_dtime_store(&dt, dst_parent, &h_path);
+       h_path.dentry = h_dst;
+       if (!isdir)
+               rerr = vfsub_unlink(h_dir, &h_path, /*force*/0);
+       else
+               rerr = vfsub_rmdir(h_dir, &h_path);
+       au_dtime_revert(&dt);
+       if (rerr) {
+               AuIOErr("failed removing broken entry(%d, %d)\n", err, rerr);
+               err = -EIO;
+       }
+
+ out:
+       dput(dst_parent);
+       return err;
+}
+
+struct au_cpup_single_args {
+       int *errp;
+       struct dentry *dentry;
+       aufs_bindex_t bdst, bsrc;
+       loff_t len;
+       unsigned int flags;
+       struct dentry *dst_parent;
+};
+
+static void au_call_cpup_single(void *args)
+{
+       struct au_cpup_single_args *a = args;
+       *a->errp = au_cpup_single(a->dentry, a->bdst, a->bsrc, a->len,
+                                 a->flags, a->dst_parent);
+}
+
+int au_sio_cpup_single(struct dentry *dentry, aufs_bindex_t bdst,
+                      aufs_bindex_t bsrc, loff_t len, unsigned int flags,
+                      struct dentry *dst_parent)
+{
+       int err, wkq_err;
+       umode_t mode;
+       struct dentry *h_dentry;
+
+       h_dentry = au_h_dptr(dentry, bsrc);
+       mode = h_dentry->d_inode->i_mode & S_IFMT;
+       if ((mode != S_IFCHR && mode != S_IFBLK)
+           || capable(CAP_MKNOD))
+               err = au_cpup_single(dentry, bdst, bsrc, len, flags,
+                                    dst_parent);
+       else {
+               struct au_cpup_single_args args = {
+                       .errp           = &err,
+                       .dentry         = dentry,
+                       .bdst           = bdst,
+                       .bsrc           = bsrc,
+                       .len            = len,
+                       .flags          = flags,
+                       .dst_parent     = dst_parent
+               };
+               wkq_err = au_wkq_wait(au_call_cpup_single, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+
+       return err;
+}
+
+/*
+ * copyup the @dentry from the first active lower branch to @bdst,
+ * using au_cpup_single().
+ */
+static int au_cpup_simple(struct dentry *dentry, aufs_bindex_t bdst, loff_t len,
+                         unsigned int flags)
+{
+       int err;
+       aufs_bindex_t bsrc, bend;
+
+       bend = au_dbend(dentry);
+       for (bsrc = bdst + 1; bsrc <= bend; bsrc++)
+               if (au_h_dptr(dentry, bsrc))
+                       break;
+
+       err = au_lkup_neg(dentry, bdst);
+       if (!err) {
+               err = au_cpup_single(dentry, bdst, bsrc, len, flags, NULL);
+               if (!err)
+                       return 0; /* success */
+
+               /* revert */
+               au_set_h_dptr(dentry, bdst, NULL);
+               au_set_dbstart(dentry, bsrc);
+       }
+
+       return err;
+}
+
+struct au_cpup_simple_args {
+       int *errp;
+       struct dentry *dentry;
+       aufs_bindex_t bdst;
+       loff_t len;
+       unsigned int flags;
+};
+
+static void au_call_cpup_simple(void *args)
+{
+       struct au_cpup_simple_args *a = args;
+       *a->errp = au_cpup_simple(a->dentry, a->bdst, a->len, a->flags);
+}
+
+int au_sio_cpup_simple(struct dentry *dentry, aufs_bindex_t bdst, loff_t len,
+                      unsigned int flags)
+{
+       int err, wkq_err;
+       unsigned char do_sio;
+       struct dentry *parent;
+       struct inode *h_dir;
+
+       parent = dget_parent(dentry);
+       h_dir = au_h_iptr(parent->d_inode, bdst);
+       do_sio = !!au_test_h_perm_sio(h_dir, MAY_EXEC | MAY_WRITE);
+       if (!do_sio) {
+               /*
+                * testing CAP_MKNOD is for generic fs,
+                * but CAP_FSETID is for xfs only, currently.
+                */
+               umode_t mode = dentry->d_inode->i_mode;
+               do_sio = (((mode & (S_IFCHR | S_IFBLK))
+                          && !capable(CAP_MKNOD))
+                         || ((mode & (S_ISUID | S_ISGID))
+                             && !capable(CAP_FSETID)));
+       }
+       if (!do_sio)
+               err = au_cpup_simple(dentry, bdst, len, flags);
+       else {
+               struct au_cpup_simple_args args = {
+                       .errp           = &err,
+                       .dentry         = dentry,
+                       .bdst           = bdst,
+                       .len            = len,
+                       .flags          = flags
+               };
+               wkq_err = au_wkq_wait(au_call_cpup_simple, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+
+       dput(parent);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * copyup the deleted file for writing.
+ */
+static int au_do_cpup_wh(struct dentry *dentry, aufs_bindex_t bdst,
+                        struct dentry *wh_dentry, struct file *file,
+                        loff_t len)
+{
+       int err;
+       aufs_bindex_t bstart;
+       struct au_dinfo *dinfo;
+       struct dentry *h_d_dst, *h_d_start;
+
+       dinfo = au_di(dentry);
+       bstart = dinfo->di_bstart;
+       h_d_dst = dinfo->di_hdentry[0 + bdst].hd_dentry;
+       dinfo->di_bstart = bdst;
+       dinfo->di_hdentry[0 + bdst].hd_dentry = wh_dentry;
+       h_d_start = dinfo->di_hdentry[0 + bstart].hd_dentry;
+       if (file)
+               dinfo->di_hdentry[0 + bstart].hd_dentry
+                       = au_h_fptr(file, au_fbstart(file))->f_dentry;
+       err = au_cpup_single(dentry, bdst, bstart, len, !AuCpup_DTIME,
+                            /*h_parent*/NULL);
+       if (!err && file) {
+               err = au_reopen_nondir(file);
+               dinfo->di_hdentry[0 + bstart].hd_dentry = h_d_start;
+       }
+       dinfo->di_hdentry[0 + bdst].hd_dentry = h_d_dst;
+       dinfo->di_bstart = bstart;
+
+       return err;
+}
+
+static int au_cpup_wh(struct dentry *dentry, aufs_bindex_t bdst, loff_t len,
+                     struct file *file)
+{
+       int err;
+       struct au_dtime dt;
+       struct dentry *parent, *h_parent, *wh_dentry;
+       struct au_branch *br;
+       struct path h_path;
+
+       br = au_sbr(dentry->d_sb, bdst);
+       parent = dget_parent(dentry);
+       h_parent = au_h_dptr(parent, bdst);
+       wh_dentry = au_whtmp_lkup(h_parent, br, &dentry->d_name);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out;
+
+       h_path.dentry = h_parent;
+       h_path.mnt = br->br_mnt;
+       au_dtime_store(&dt, parent, &h_path);
+       err = au_do_cpup_wh(dentry, bdst, wh_dentry, file, len);
+       if (unlikely(err))
+               goto out_wh;
+
+       dget(wh_dentry);
+       h_path.dentry = wh_dentry;
+       err = vfsub_unlink(h_parent->d_inode, &h_path, /*force*/0);
+       if (unlikely(err)) {
+               AuIOErr("failed remove copied-up tmp file %.*s(%d)\n",
+                       AuDLNPair(wh_dentry), err);
+               err = -EIO;
+       }
+       au_dtime_revert(&dt);
+       au_set_hi_wh(dentry->d_inode, bdst, wh_dentry);
+
+ out_wh:
+       dput(wh_dentry);
+ out:
+       dput(parent);
+       return err;
+}
+
+struct au_cpup_wh_args {
+       int *errp;
+       struct dentry *dentry;
+       aufs_bindex_t bdst;
+       loff_t len;
+       struct file *file;
+};
+
+static void au_call_cpup_wh(void *args)
+{
+       struct au_cpup_wh_args *a = args;
+       *a->errp = au_cpup_wh(a->dentry, a->bdst, a->len, a->file);
+}
+
+int au_sio_cpup_wh(struct dentry *dentry, aufs_bindex_t bdst, loff_t len,
+                  struct file *file)
+{
+       int err, wkq_err;
+       struct dentry *parent, *h_orph, *h_parent, *h_dentry;
+       struct inode *dir, *h_dir, *h_tmpdir, *h_inode;
+       struct au_wbr *wbr;
+
+       parent = dget_parent(dentry);
+       dir = parent->d_inode;
+       h_orph = NULL;
+       h_parent = NULL;
+       h_dir = au_igrab(au_h_iptr(dir, bdst));
+       h_tmpdir = h_dir;
+       if (!h_dir->i_nlink) {
+               wbr = au_sbr(dentry->d_sb, bdst)->br_wbr;
+               h_orph = wbr->wbr_orph;
+
+               h_parent = dget(au_h_dptr(parent, bdst));
+               au_set_h_dptr(parent, bdst, NULL);
+               au_set_h_dptr(parent, bdst, dget(h_orph));
+               h_tmpdir = h_orph->d_inode;
+               au_set_h_iptr(dir, bdst, NULL, 0);
+               au_set_h_iptr(dir, bdst, au_igrab(h_tmpdir), /*flags*/0);
+
+               /* this temporary unlock is safe */
+               if (file)
+                       h_dentry = au_h_fptr(file, au_fbstart(file))->f_dentry;
+               else
+                       h_dentry = au_h_dptr(dentry, au_dbstart(dentry));
+               h_inode = h_dentry->d_inode;
+               IMustLock(h_inode);
+               mutex_unlock(&h_inode->i_mutex);
+               mutex_lock_nested(&h_tmpdir->i_mutex, AuLsc_I_PARENT2);
+               mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+       }
+
+       if (!au_test_h_perm_sio(h_tmpdir, MAY_EXEC | MAY_WRITE))
+               err = au_cpup_wh(dentry, bdst, len, file);
+       else {
+               struct au_cpup_wh_args args = {
+                       .errp   = &err,
+                       .dentry = dentry,
+                       .bdst   = bdst,
+                       .len    = len,
+                       .file   = file
+               };
+               wkq_err = au_wkq_wait(au_call_cpup_wh, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+
+       if (h_orph) {
+               mutex_unlock(&h_tmpdir->i_mutex);
+               au_set_h_iptr(dir, bdst, NULL, 0);
+               au_set_h_iptr(dir, bdst, au_igrab(h_dir), /*flags*/0);
+               au_set_h_dptr(parent, bdst, NULL);
+               au_set_h_dptr(parent, bdst, h_parent);
+       }
+       iput(h_dir);
+       dput(parent);
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * generic routine for both of copy-up and copy-down.
+ */
+/* cf. revalidate function in file.c */
+int au_cp_dirs(struct dentry *dentry, aufs_bindex_t bdst,
+              int (*cp)(struct dentry *dentry, aufs_bindex_t bdst,
+                        struct dentry *h_parent, void *arg),
+              void *arg)
+{
+       int err;
+       struct au_pin pin;
+       struct dentry *d, *parent, *h_parent, *real_parent;
+
+       err = 0;
+       parent = dget_parent(dentry);
+       if (IS_ROOT(parent))
+               goto out;
+
+       au_pin_init(&pin, dentry, bdst, AuLsc_DI_PARENT2, AuLsc_I_PARENT2,
+                   au_opt_udba(dentry->d_sb), AuPin_MNT_WRITE);
+
+       /* do not use au_dpage */
+       real_parent = parent;
+       while (1) {
+               dput(parent);
+               parent = dget_parent(dentry);
+               h_parent = au_h_dptr(parent, bdst);
+               if (h_parent)
+                       goto out; /* success */
+
+               /* find top dir which is necessary to cpup */
+               do {
+                       d = parent;
+                       dput(parent);
+                       parent = dget_parent(d);
+                       di_read_lock_parent3(parent, !AuLock_IR);
+                       h_parent = au_h_dptr(parent, bdst);
+                       di_read_unlock(parent, !AuLock_IR);
+               } while (!h_parent);
+
+               if (d != real_parent)
+                       di_write_lock_child3(d);
+
+               /* somebody else might create while we were sleeping */
+               if (!au_h_dptr(d, bdst) || !au_h_dptr(d, bdst)->d_inode) {
+                       if (au_h_dptr(d, bdst))
+                               au_update_dbstart(d);
+
+                       au_pin_set_dentry(&pin, d);
+                       err = au_do_pin(&pin);
+                       if (!err) {
+                               err = cp(d, bdst, h_parent, arg);
+                               au_unpin(&pin);
+                       }
+               }
+
+               if (d != real_parent)
+                       di_write_unlock(d);
+               if (unlikely(err))
+                       break;
+       }
+
+ out:
+       dput(parent);
+       return err;
+}
+
+static int au_cpup_dir(struct dentry *dentry, aufs_bindex_t bdst,
+                      struct dentry *h_parent __maybe_unused ,
+                      void *arg __maybe_unused)
+{
+       return au_sio_cpup_simple(dentry, bdst, -1, AuCpup_DTIME);
+}
+
+int au_cpup_dirs(struct dentry *dentry, aufs_bindex_t bdst)
+{
+       return au_cp_dirs(dentry, bdst, au_cpup_dir, NULL);
+}
+
+int au_test_and_cpup_dirs(struct dentry *dentry, aufs_bindex_t bdst)
+{
+       int err;
+       struct dentry *parent;
+       struct inode *dir;
+
+       parent = dget_parent(dentry);
+       dir = parent->d_inode;
+       err = 0;
+       if (au_h_iptr(dir, bdst))
+               goto out;
+
+       di_read_unlock(parent, AuLock_IR);
+       di_write_lock_parent(parent);
+       /* someone else might change our inode while we were sleeping */
+       if (!au_h_iptr(dir, bdst))
+               err = au_cpup_dirs(dentry, bdst);
+       di_downgrade_lock(parent, AuLock_IR);
+
+ out:
+       dput(parent);
+       return err;
+}
diff --git a/fs/aufs/cpup.h b/fs/aufs/cpup.h
new file mode 100644
index 0000000..240014a
--- /dev/null
+++ b/fs/aufs/cpup.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * copy-up/down functions
+ */
+
+#ifndef __AUFS_CPUP_H__
+#define __AUFS_CPUP_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/aufs_type.h>
+
+void au_cpup_attr_flags(struct inode *dst, struct inode *src);
+void au_cpup_attr_timesizes(struct inode *inode);
+void au_cpup_attr_nlink(struct inode *inode, int force);
+void au_cpup_attr_changeable(struct inode *inode);
+void au_cpup_igen(struct inode *inode, struct inode *h_inode);
+void au_cpup_attr_all(struct inode *inode, int force);
+
+/* ---------------------------------------------------------------------- */
+
+/* cpup flags */
+#define AuCpup_DTIME   1               /* do dtime_store/revert */
+#define AuCpup_KEEPLINO        (1 << 1)        /* do not clear the lower xino,
+                                          for link(2) */
+#define au_ftest_cpup(flags, name)     ((flags) & AuCpup_##name)
+#define au_fset_cpup(flags, name)      { (flags) |= AuCpup_##name; }
+#define au_fclr_cpup(flags, name)      { (flags) &= ~AuCpup_##name; }
+
+int au_copy_file(struct file *dst, struct file *src, loff_t len);
+int au_sio_cpup_single(struct dentry *dentry, aufs_bindex_t bdst,
+                      aufs_bindex_t bsrc, loff_t len, unsigned int flags,
+                      struct dentry *dst_parent);
+int au_sio_cpup_simple(struct dentry *dentry, aufs_bindex_t bdst, loff_t len,
+                      unsigned int flags);
+int au_sio_cpup_wh(struct dentry *dentry, aufs_bindex_t bdst, loff_t len,
+                  struct file *file);
+
+int au_cp_dirs(struct dentry *dentry, aufs_bindex_t bdst,
+              int (*cp)(struct dentry *dentry, aufs_bindex_t bdst,
+                        struct dentry *h_parent, void *arg),
+              void *arg);
+int au_cpup_dirs(struct dentry *dentry, aufs_bindex_t bdst);
+int au_test_and_cpup_dirs(struct dentry *dentry, aufs_bindex_t bdst);
+
+/* ---------------------------------------------------------------------- */
+
+/* keep timestamps when copyup */
+struct au_dtime {
+       struct dentry *dt_dentry;
+       struct path dt_h_path;
+       struct timespec dt_atime, dt_mtime;
+};
+void au_dtime_store(struct au_dtime *dt, struct dentry *dentry,
+                   struct path *h_path);
+void au_dtime_revert(struct au_dtime *dt);
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_CPUP_H__ */
diff --git a/fs/aufs/dbgaufs.c b/fs/aufs/dbgaufs.c
new file mode 100644
index 0000000..cb04b5d
--- /dev/null
+++ b/fs/aufs/dbgaufs.c
@@ -0,0 +1,304 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * debugfs interface
+ */
+
+#include <linux/debugfs.h>
+#include "aufs.h"
+
+#ifndef CONFIG_SYSFS
+#error DEBUG_FS depends upon SYSFS
+#endif
+
+static struct dentry *dbgaufs;
+static const mode_t dbgaufs_mode = S_IRUSR | S_IRGRP | S_IROTH;
+
+/* 20 is max digits length of ulong 64 */
+struct dbgaufs_arg {
+       int n;
+       char a[20 * 4];
+};
+
+/*
+ * common function for all XINO files
+ */
+static int dbgaufs_xi_release(struct inode *inode __maybe_unused,
+                             struct file *file)
+{
+       kfree(file->private_data);
+       return 0;
+}
+
+static int dbgaufs_xi_open(struct file *xf, struct file *file, int do_fcnt)
+{
+       int err;
+       struct kstat st;
+       struct dbgaufs_arg *p;
+
+       err = -ENOMEM;
+       p = kmalloc(sizeof(*p), GFP_NOFS);
+       if (unlikely(!p))
+               goto out;
+
+       err = 0;
+       p->n = 0;
+       file->private_data = p;
+       if (!xf)
+               goto out;
+
+       err = vfs_getattr(xf->f_vfsmnt, xf->f_dentry, &st);
+       if (!err) {
+               if (do_fcnt)
+                       p->n = snprintf
+                               (p->a, sizeof(p->a), "%ld, %llux%lu %lld\n",
+                                (long)file_count(xf), st.blocks, st.blksize,
+                                (long long)st.size);
+               else
+                       p->n = snprintf(p->a, sizeof(p->a), "%llux%lu %lld\n",
+                                       st.blocks, st.blksize,
+                                       (long long)st.size);
+               AuDebugOn(p->n >= sizeof(p->a));
+       } else {
+               p->n = snprintf(p->a, sizeof(p->a), "err %d\n", err);
+               err = 0;
+       }
+
+ out:
+       return err;
+
+}
+
+static ssize_t dbgaufs_xi_read(struct file *file, char __user *buf,
+                              size_t count, loff_t *ppos)
+{
+       struct dbgaufs_arg *p;
+
+       p = file->private_data;
+       return simple_read_from_buffer(buf, count, ppos, p->a, p->n);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int dbgaufs_xib_open(struct inode *inode, struct file *file)
+{
+       int err;
+       struct au_sbinfo *sbinfo;
+       struct super_block *sb;
+
+       sbinfo = inode->i_private;
+       sb = sbinfo->si_sb;
+       si_noflush_read_lock(sb);
+       err = dbgaufs_xi_open(sbinfo->si_xib, file, /*do_fcnt*/0);
+       si_read_unlock(sb);
+       return err;
+}
+
+static const struct file_operations dbgaufs_xib_fop = {
+       .open           = dbgaufs_xib_open,
+       .release        = dbgaufs_xi_release,
+       .read           = dbgaufs_xi_read
+};
+
+/* ---------------------------------------------------------------------- */
+
+#define DbgaufsXi_PREFIX "xi"
+
+static int dbgaufs_xino_open(struct inode *inode, struct file *file)
+{
+       int err;
+       long l;
+       struct au_sbinfo *sbinfo;
+       struct super_block *sb;
+       struct file *xf;
+       struct qstr *name;
+
+       err = -ENOENT;
+       xf = NULL;
+       name = &file->f_dentry->d_name;
+       if (unlikely(name->len < sizeof(DbgaufsXi_PREFIX)
+                    || memcmp(name->name, DbgaufsXi_PREFIX,
+                              sizeof(DbgaufsXi_PREFIX) - 1)))
+               goto out;
+       err = strict_strtol(name->name + sizeof(DbgaufsXi_PREFIX) - 1, 10, &l);
+       if (unlikely(err))
+               goto out;
+
+       sbinfo = inode->i_private;
+       sb = sbinfo->si_sb;
+       si_noflush_read_lock(sb);
+       if (l <= au_sbend(sb)) {
+               xf = au_sbr(sb, (aufs_bindex_t)l)->br_xino.xi_file;
+               err = dbgaufs_xi_open(xf, file, /*do_fcnt*/1);
+       } else
+               err = -ENOENT;
+       si_read_unlock(sb);
+
+ out:
+       return err;
+}
+
+static const struct file_operations dbgaufs_xino_fop = {
+       .open           = dbgaufs_xino_open,
+       .release        = dbgaufs_xi_release,
+       .read           = dbgaufs_xi_read
+};
+
+void dbgaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex)
+{
+       aufs_bindex_t bend;
+       struct au_branch *br;
+       struct au_xino_file *xi;
+
+       if (!au_sbi(sb)->si_dbgaufs)
+               return;
+
+       bend = au_sbend(sb);
+       for (; bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               xi = &br->br_xino;
+               if (xi->xi_dbgaufs) {
+                       debugfs_remove(xi->xi_dbgaufs);
+                       xi->xi_dbgaufs = NULL;
+               }
+       }
+}
+
+void dbgaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex)
+{
+       struct au_sbinfo *sbinfo;
+       struct dentry *parent;
+       struct au_branch *br;
+       struct au_xino_file *xi;
+       aufs_bindex_t bend;
+       char name[sizeof(DbgaufsXi_PREFIX) + 5]; /* "xi" bindex NULL */
+
+       sbinfo = au_sbi(sb);
+       parent = sbinfo->si_dbgaufs;
+       if (!parent)
+               return;
+
+       bend = au_sbend(sb);
+       for (; bindex <= bend; bindex++) {
+               snprintf(name, sizeof(name), DbgaufsXi_PREFIX "%d", bindex);
+               br = au_sbr(sb, bindex);
+               xi = &br->br_xino;
+               AuDebugOn(xi->xi_dbgaufs);
+               xi->xi_dbgaufs = debugfs_create_file(name, dbgaufs_mode, parent,
+                                                    sbinfo, &dbgaufs_xino_fop);
+               /* ignore an error */
+               if (unlikely(!xi->xi_dbgaufs))
+                       AuWarn1("failed %s under debugfs\n", name);
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+#ifdef CONFIG_AUFS_EXPORT
+static int dbgaufs_xigen_open(struct inode *inode, struct file *file)
+{
+       int err;
+       struct au_sbinfo *sbinfo;
+       struct super_block *sb;
+
+       sbinfo = inode->i_private;
+       sb = sbinfo->si_sb;
+       si_noflush_read_lock(sb);
+       err = dbgaufs_xi_open(sbinfo->si_xigen, file, /*do_fcnt*/0);
+       si_read_unlock(sb);
+       return err;
+}
+
+static const struct file_operations dbgaufs_xigen_fop = {
+       .open           = dbgaufs_xigen_open,
+       .release        = dbgaufs_xi_release,
+       .read           = dbgaufs_xi_read
+};
+
+static int dbgaufs_xigen_init(struct au_sbinfo *sbinfo)
+{
+       int err;
+
+       err = -EIO;
+       sbinfo->si_dbgaufs_xigen = debugfs_create_file
+               ("xigen", dbgaufs_mode, sbinfo->si_dbgaufs, sbinfo,
+                &dbgaufs_xigen_fop);
+       if (sbinfo->si_dbgaufs_xigen)
+               err = 0;
+
+       return err;
+}
+#else
+static int dbgaufs_xigen_init(struct au_sbinfo *sbinfo)
+{
+       return 0;
+}
+#endif /* CONFIG_AUFS_EXPORT */
+
+/* ---------------------------------------------------------------------- */
+
+void dbgaufs_si_fin(struct au_sbinfo *sbinfo)
+{
+       debugfs_remove_recursive(sbinfo->si_dbgaufs);
+       sbinfo->si_dbgaufs = NULL;
+       kobject_put(&sbinfo->si_kobj);
+}
+
+int dbgaufs_si_init(struct au_sbinfo *sbinfo)
+{
+       int err;
+       char name[SysaufsSiNameLen];
+
+       err = -ENOENT;
+       if (!dbgaufs) {
+               AuErr1("/debug/aufs is uninitialized\n");
+               goto out;
+       }
+
+       err = -EIO;
+       sysaufs_name(sbinfo, name);
+       sbinfo->si_dbgaufs = debugfs_create_dir(name, dbgaufs);
+       if (unlikely(!sbinfo->si_dbgaufs))
+               goto out;
+       kobject_get(&sbinfo->si_kobj);
+
+       sbinfo->si_dbgaufs_xib = debugfs_create_file
+               ("xib", dbgaufs_mode, sbinfo->si_dbgaufs, sbinfo,
+                &dbgaufs_xib_fop);
+       if (unlikely(!sbinfo->si_dbgaufs_xib))
+               goto out_dir;
+
+       err = dbgaufs_xigen_init(sbinfo);
+       if (!err)
+               goto out; /* success */
+
+ out_dir:
+       dbgaufs_si_fin(sbinfo);
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void dbgaufs_fin(void)
+{
+       debugfs_remove(dbgaufs);
+}
+
+int __init dbgaufs_init(void)
+{
+       int err;
+
+       err = -EIO;
+       dbgaufs = debugfs_create_dir(AUFS_NAME, NULL);
+       if (dbgaufs)
+               err = 0;
+       return err;
+}
diff --git a/fs/aufs/dbgaufs.h b/fs/aufs/dbgaufs.h
new file mode 100644
index 0000000..dfb0f0a
--- /dev/null
+++ b/fs/aufs/dbgaufs.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * debugfs interface
+ */
+
+#ifndef __DBGAUFS_H__
+#define __DBGAUFS_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/aufs_type.h>
+
+struct au_sbinfo;
+#ifdef CONFIG_DEBUG_FS
+/* dbgaufs.c */
+void dbgaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex);
+void dbgaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex);
+void dbgaufs_si_fin(struct au_sbinfo *sbinfo);
+int dbgaufs_si_init(struct au_sbinfo *sbinfo);
+void dbgaufs_fin(void);
+int __init dbgaufs_init(void);
+
+#else
+
+static inline
+void dbgaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex)
+{
+       /* empty */
+}
+
+static inline
+void dbgaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex)
+{
+       /* empty */
+}
+
+static inline
+void dbgaufs_si_fin(struct au_sbinfo *sbinfo)
+{
+       /* empty */
+}
+
+static inline
+int dbgaufs_si_init(struct au_sbinfo *sbinfo)
+{
+       return 0;
+}
+
+#define dbgaufs_fin()  do {} while (0)
+
+static inline
+int __init dbgaufs_init(void)
+{
+       return 0;
+}
+#endif /* CONFIG_DEBUG_FS */
+
+#endif /* __KERNEL__ */
+#endif /* __DBGAUFS_H__ */
diff --git a/fs/aufs/dcsub.c b/fs/aufs/dcsub.c
new file mode 100644
index 0000000..e4597e4
--- /dev/null
+++ b/fs/aufs/dcsub.c
@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sub-routines for dentry cache
+ */
+
+#include "aufs.h"
+
+static void au_dpage_free(struct au_dpage *dpage)
+{
+       int i;
+       struct dentry **p;
+
+       p = dpage->dentries;
+       for (i = 0; i < dpage->ndentry; i++)
+               dput(*p++);
+       free_page((unsigned long)dpage->dentries);
+}
+
+int au_dpages_init(struct au_dcsub_pages *dpages, gfp_t gfp)
+{
+       int err;
+       void *p;
+
+       err = -ENOMEM;
+       dpages->dpages = kmalloc(sizeof(*dpages->dpages), gfp);
+       if (unlikely(!dpages->dpages))
+               goto out;
+
+       p = (void *)__get_free_page(gfp);
+       if (unlikely(!p))
+               goto out_dpages;
+
+       dpages->dpages[0].ndentry = 0;
+       dpages->dpages[0].dentries = p;
+       dpages->ndpage = 1;
+       return 0; /* success */
+
+ out_dpages:
+       kfree(dpages->dpages);
+ out:
+       return err;
+}
+
+void au_dpages_free(struct au_dcsub_pages *dpages)
+{
+       int i;
+       struct au_dpage *p;
+
+       p = dpages->dpages;
+       for (i = 0; i < dpages->ndpage; i++)
+               au_dpage_free(p++);
+       kfree(dpages->dpages);
+}
+
+static int au_dpages_append(struct au_dcsub_pages *dpages,
+                           struct dentry *dentry, gfp_t gfp)
+{
+       int err, sz;
+       struct au_dpage *dpage;
+       void *p;
+
+       dpage = dpages->dpages + dpages->ndpage - 1;
+       sz = PAGE_SIZE / sizeof(dentry);
+       if (unlikely(dpage->ndentry >= sz)) {
+               AuLabel(new dpage);
+               err = -ENOMEM;
+               sz = dpages->ndpage * sizeof(*dpages->dpages);
+               p = au_kzrealloc(dpages->dpages, sz,
+                                sz + sizeof(*dpages->dpages), gfp);
+               if (unlikely(!p))
+                       goto out;
+
+               dpages->dpages = p;
+               dpage = dpages->dpages + dpages->ndpage;
+               p = (void *)__get_free_page(gfp);
+               if (unlikely(!p))
+                       goto out;
+
+               dpage->ndentry = 0;
+               dpage->dentries = p;
+               dpages->ndpage++;
+       }
+
+       dpage->dentries[dpage->ndentry++] = dget(dentry);
+       return 0; /* success */
+
+ out:
+       return err;
+}
+
+int au_dcsub_pages(struct au_dcsub_pages *dpages, struct dentry *root,
+                  au_dpages_test test, void *arg)
+{
+       int err;
+       struct dentry *this_parent = root;
+       struct list_head *next;
+       struct super_block *sb = root->d_sb;
+
+       err = 0;
+       spin_lock(&dcache_lock);
+ repeat:
+       next = this_parent->d_subdirs.next;
+ resume:
+       if (this_parent->d_sb == sb
+           && !IS_ROOT(this_parent)
+           && atomic_read(&this_parent->d_count)
+           && this_parent->d_inode
+           && (!test || test(this_parent, arg))) {
+               err = au_dpages_append(dpages, this_parent, GFP_ATOMIC);
+               if (unlikely(err))
+                       goto out;
+       }
+
+       while (next != &this_parent->d_subdirs) {
+               struct list_head *tmp = next;
+               struct dentry *dentry = list_entry(tmp, struct dentry,
+                                                  d_u.d_child);
+               next = tmp->next;
+               if (/*d_unhashed(dentry) || */!dentry->d_inode)
+                       continue;
+               if (!list_empty(&dentry->d_subdirs)) {
+                       this_parent = dentry;
+                       goto repeat;
+               }
+               if (dentry->d_sb == sb
+                   && atomic_read(&dentry->d_count)
+                   && (!test || test(dentry, arg))) {
+                       err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
+                       if (unlikely(err))
+                               goto out;
+               }
+       }
+
+       if (this_parent != root) {
+               next = this_parent->d_u.d_child.next;
+               this_parent = this_parent->d_parent; /* dcache_lock is locked */
+               goto resume;
+       }
+ out:
+       spin_unlock(&dcache_lock);
+       return err;
+}
+
+int au_dcsub_pages_rev(struct au_dcsub_pages *dpages, struct dentry *dentry,
+                      int do_include, au_dpages_test test, void *arg)
+{
+       int err;
+
+       err = 0;
+       spin_lock(&dcache_lock);
+       if (do_include && (!test || test(dentry, arg))) {
+               err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
+               if (unlikely(err))
+                       goto out;
+       }
+       while (!IS_ROOT(dentry)) {
+               dentry = dentry->d_parent; /* dcache_lock is locked */
+               if (!test || test(dentry, arg)) {
+                       err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
+                       if (unlikely(err))
+                               break;
+               }
+       }
+
+ out:
+       spin_unlock(&dcache_lock);
+
+       return err;
+}
+
+struct dentry *au_test_subdir(struct dentry *d1, struct dentry *d2)
+{
+       struct dentry *trap, **dentries;
+       int err, i, j;
+       struct au_dcsub_pages dpages;
+       struct au_dpage *dpage;
+
+       trap = ERR_PTR(-ENOMEM);
+       err = au_dpages_init(&dpages, GFP_NOFS);
+       if (unlikely(err))
+               goto out;
+       err = au_dcsub_pages_rev(&dpages, d1, /*do_include*/1, NULL, NULL);
+       if (unlikely(err))
+               goto out_dpages;
+
+       trap = d1;
+       for (i = 0; !err && i < dpages.ndpage; i++) {
+               dpage = dpages.dpages + i;
+               dentries = dpage->dentries;
+               for (j = 0; !err && j < dpage->ndentry; j++) {
+                       struct dentry *d;
+
+                       d = dentries[j];
+                       err = (d == d2);
+                       if (!err)
+                               trap = d;
+               }
+       }
+       if (!err)
+               trap = NULL;
+
+ out_dpages:
+       au_dpages_free(&dpages);
+ out:
+       return trap;
+}
diff --git a/fs/aufs/dcsub.h b/fs/aufs/dcsub.h
new file mode 100644
index 0000000..89a7745
--- /dev/null
+++ b/fs/aufs/dcsub.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sub-routines for dentry cache
+ */
+
+#ifndef __AUFS_DCSUB_H__
+#define __AUFS_DCSUB_H__
+
+#ifdef __KERNEL__
+
+#include <linux/dcache.h>
+
+struct au_dpage {
+       int ndentry;
+       struct dentry **dentries;
+};
+
+struct au_dcsub_pages {
+       int ndpage;
+       struct au_dpage *dpages;
+};
+
+/* ---------------------------------------------------------------------- */
+
+int au_dpages_init(struct au_dcsub_pages *dpages, gfp_t gfp);
+void au_dpages_free(struct au_dcsub_pages *dpages);
+typedef int (*au_dpages_test)(struct dentry *dentry, void *arg);
+int au_dcsub_pages(struct au_dcsub_pages *dpages, struct dentry *root,
+                  au_dpages_test test, void *arg);
+int au_dcsub_pages_rev(struct au_dcsub_pages *dpages, struct dentry *dentry,
+                      int do_include, au_dpages_test test, void *arg);
+struct dentry *au_test_subdir(struct dentry *d1, struct dentry *d2);
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_DCSUB_H__ */
diff --git a/fs/aufs/debug.c b/fs/aufs/debug.c
new file mode 100644
index 0000000..de38931
--- /dev/null
+++ b/fs/aufs/debug.c
@@ -0,0 +1,416 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * debug print functions
+ */
+
+#include "aufs.h"
+
+int aufs_debug;
+MODULE_PARM_DESC(debug, "debug print");
+module_param_named(debug, aufs_debug, int, S_IRUGO | S_IWUSR | S_IWGRP);
+
+char *au_plevel = KERN_DEBUG;
+#define dpri(fmt, arg...) do { \
+       if (au_debug_test()) \
+               printk("%s" fmt, au_plevel, ##arg); \
+} while (0)
+
+/* ---------------------------------------------------------------------- */
+
+void au_dpri_whlist(struct au_nhash *whlist)
+{
+       unsigned long ul, n;
+       struct hlist_head *head;
+       struct au_vdir_wh *tpos;
+       struct hlist_node *pos;
+
+       n = whlist->nh_num;
+       head = whlist->nh_head;
+       for (ul = 0; ul < n; ul++) {
+               hlist_for_each_entry(tpos, pos, head, wh_hash)
+                       dpri("b%d, %.*s, %d\n",
+                            tpos->wh_bindex,
+                            tpos->wh_str.len, tpos->wh_str.name,
+                            tpos->wh_str.len);
+               head++;
+       }
+}
+
+void au_dpri_vdir(struct au_vdir *vdir)
+{
+       unsigned long ul;
+       union au_vdir_deblk_p p;
+       unsigned char *o;
+
+       if (!vdir || IS_ERR(vdir)) {
+               dpri("err %ld\n", PTR_ERR(vdir));
+               return;
+       }
+
+       dpri("deblk %u, nblk %lu, deblk %p, last{%lu, %p}, ver %lu\n",
+            vdir->vd_deblk_sz, vdir->vd_nblk, vdir->vd_deblk,
+            vdir->vd_last.ul, vdir->vd_last.p.deblk, vdir->vd_version);
+       for (ul = 0; ul < vdir->vd_nblk; ul++) {
+               p.deblk = vdir->vd_deblk[ul];
+               o = p.deblk;
+               dpri("[%lu]: %p\n", ul, o);
+       }
+}
+
+static int do_pri_inode(aufs_bindex_t bindex, struct inode *inode,
+                       struct dentry *wh)
+{
+       char *n = NULL;
+       int l = 0;
+
+       if (!inode || IS_ERR(inode)) {
+               dpri("i%d: err %ld\n", bindex, PTR_ERR(inode));
+               return -1;
+       }
+
+       /* the type of i_blocks depends upon CONFIG_LSF */
+       BUILD_BUG_ON(sizeof(inode->i_blocks) != sizeof(unsigned long)
+                    && sizeof(inode->i_blocks) != sizeof(u64));
+       if (wh) {
+               n = (void *)wh->d_name.name;
+               l = wh->d_name.len;
+       }
+
+       dpri("i%d: i%lu, %s, cnt %d, nl %u, 0%o, sz %llu, blk %llu,"
+            " ct %lld, np %lu, st 0x%lx, f 0x%x, g %x%s%.*s\n",
+            bindex,
+            inode->i_ino, inode->i_sb ? au_sbtype(inode->i_sb) : "??",
+            atomic_read(&inode->i_count), inode->i_nlink, inode->i_mode,
+            i_size_read(inode), (unsigned long long)inode->i_blocks,
+            (long long)timespec_to_ns(&inode->i_ctime) & 0x0ffff,
+            inode->i_mapping ? inode->i_mapping->nrpages : 0,
+            inode->i_state, inode->i_flags, inode->i_generation,
+            l ? ", wh " : "", l, n);
+       return 0;
+}
+
+void au_dpri_inode(struct inode *inode)
+{
+       struct au_iinfo *iinfo;
+       aufs_bindex_t bindex;
+       int err;
+
+       err = do_pri_inode(-1, inode, NULL);
+       if (err || !au_test_aufs(inode->i_sb))
+               return;
+
+       iinfo = au_ii(inode);
+       if (!iinfo)
+               return;
+       dpri("i-1: bstart %d, bend %d, gen %d\n",
+            iinfo->ii_bstart, iinfo->ii_bend, au_iigen(inode));
+       if (iinfo->ii_bstart < 0)
+               return;
+       for (bindex = iinfo->ii_bstart; bindex <= iinfo->ii_bend; bindex++)
+               do_pri_inode(bindex, iinfo->ii_hinode[0 + bindex].hi_inode,
+                            iinfo->ii_hinode[0 + bindex].hi_whdentry);
+}
+
+static int do_pri_dentry(aufs_bindex_t bindex, struct dentry *dentry)
+{
+       struct dentry *wh = NULL;
+
+       if (!dentry || IS_ERR(dentry)) {
+               dpri("d%d: err %ld\n", bindex, PTR_ERR(dentry));
+               return -1;
+       }
+       /* do not call dget_parent() here */
+       dpri("d%d: %.*s?/%.*s, %s, cnt %d, flags 0x%x\n",
+            bindex,
+            AuDLNPair(dentry->d_parent), AuDLNPair(dentry),
+            dentry->d_sb ? au_sbtype(dentry->d_sb) : "??",
+            atomic_read(&dentry->d_count), dentry->d_flags);
+       if (bindex >= 0 && dentry->d_inode && au_test_aufs(dentry->d_sb)) {
+               struct au_iinfo *iinfo = au_ii(dentry->d_inode);
+               if (iinfo)
+                       wh = iinfo->ii_hinode[0 + bindex].hi_whdentry;
+       }
+       do_pri_inode(bindex, dentry->d_inode, wh);
+       return 0;
+}
+
+void au_dpri_dentry(struct dentry *dentry)
+{
+       struct au_dinfo *dinfo;
+       aufs_bindex_t bindex;
+       int err;
+
+       err = do_pri_dentry(-1, dentry);
+       if (err || !au_test_aufs(dentry->d_sb))
+               return;
+
+       dinfo = au_di(dentry);
+       if (!dinfo)
+               return;
+       dpri("d-1: bstart %d, bend %d, bwh %d, bdiropq %d, gen %d\n",
+            dinfo->di_bstart, dinfo->di_bend,
+            dinfo->di_bwh, dinfo->di_bdiropq, au_digen(dentry));
+       if (dinfo->di_bstart < 0)
+               return;
+       for (bindex = dinfo->di_bstart; bindex <= dinfo->di_bend; bindex++)
+               do_pri_dentry(bindex, dinfo->di_hdentry[0 + bindex].hd_dentry);
+}
+
+static int do_pri_file(aufs_bindex_t bindex, struct file *file)
+{
+       char a[32];
+
+       if (!file || IS_ERR(file)) {
+               dpri("f%d: err %ld\n", bindex, PTR_ERR(file));
+               return -1;
+       }
+       a[0] = 0;
+       if (bindex < 0
+           && file->f_dentry
+           && au_test_aufs(file->f_dentry->d_sb)
+           && au_fi(file))
+               snprintf(a, sizeof(a), ", mmapped %d", au_test_mmapped(file));
+       dpri("f%d: mode 0x%x, flags 0%o, cnt %ld, pos %llu%s\n",
+            bindex, file->f_mode, file->f_flags, (long)file_count(file),
+            file->f_pos, a);
+       if (file->f_dentry)
+               do_pri_dentry(bindex, file->f_dentry);
+       return 0;
+}
+
+void au_dpri_file(struct file *file)
+{
+       struct au_finfo *finfo;
+       aufs_bindex_t bindex;
+       int err;
+
+       err = do_pri_file(-1, file);
+       if (err || !file->f_dentry || !au_test_aufs(file->f_dentry->d_sb))
+               return;
+
+       finfo = au_fi(file);
+       if (!finfo)
+               return;
+       if (finfo->fi_bstart < 0)
+               return;
+       for (bindex = finfo->fi_bstart; bindex <= finfo->fi_bend; bindex++) {
+               struct au_hfile *hf;
+
+               hf = finfo->fi_hfile + bindex;
+               do_pri_file(bindex, hf ? hf->hf_file : NULL);
+       }
+}
+
+static int do_pri_br(aufs_bindex_t bindex, struct au_branch *br)
+{
+       struct vfsmount *mnt;
+       struct super_block *sb;
+
+       if (!br || IS_ERR(br))
+               goto out;
+       mnt = br->br_mnt;
+       if (!mnt || IS_ERR(mnt))
+               goto out;
+       sb = mnt->mnt_sb;
+       if (!sb || IS_ERR(sb))
+               goto out;
+
+       dpri("s%d: {perm 0x%x, cnt %d, wbr %p}, "
+            "%s, dev 0x%02x%02x, flags 0x%lx, cnt(BIAS) %d, active %d, "
+            "xino %d\n",
+            bindex, br->br_perm, atomic_read(&br->br_count), br->br_wbr,
+            au_sbtype(sb), MAJOR(sb->s_dev), MINOR(sb->s_dev),
+            sb->s_flags, sb->s_count - S_BIAS,
+            atomic_read(&sb->s_active), !!br->br_xino.xi_file);
+       return 0;
+
+ out:
+       dpri("s%d: err %ld\n", bindex, PTR_ERR(br));
+       return -1;
+}
+
+void au_dpri_sb(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+       aufs_bindex_t bindex;
+       int err;
+       /* to reuduce stack size */
+       struct {
+               struct vfsmount mnt;
+               struct au_branch fake;
+       } *a;
+
+       /* this function can be called from magic sysrq */
+       a = kzalloc(sizeof(*a), GFP_ATOMIC);
+       if (unlikely(!a)) {
+               dpri("no memory\n");
+               return;
+       }
+
+       a->mnt.mnt_sb = sb;
+       a->fake.br_perm = 0;
+       a->fake.br_mnt = &a->mnt;
+       a->fake.br_xino.xi_file = NULL;
+       atomic_set(&a->fake.br_count, 0);
+       smp_mb(); /* atomic_set */
+       err = do_pri_br(-1, &a->fake);
+       kfree(a);
+       dpri("dev 0x%x\n", sb->s_dev);
+       if (err || !au_test_aufs(sb))
+               return;
+
+       sbinfo = au_sbi(sb);
+       if (!sbinfo)
+               return;
+       dpri("nw %d, gen %u, kobj %d\n",
+            atomic_read(&sbinfo->si_nowait.nw_len), sbinfo->si_generation,
+            atomic_read(&sbinfo->si_kobj.kref.refcount));
+       for (bindex = 0; bindex <= sbinfo->si_bend; bindex++)
+               do_pri_br(bindex, sbinfo->si_branch[0 + bindex]);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_dbg_sleep_jiffy(int jiffy)
+{
+       while (jiffy)
+               jiffy = schedule_timeout_uninterruptible(jiffy);
+}
+
+void au_dbg_iattr(struct iattr *ia)
+{
+#define AuBit(name)    if (ia->ia_valid & ATTR_ ## name) \
+                               dpri(#name "\n")
+       AuBit(MODE);
+       AuBit(UID);
+       AuBit(GID);
+       AuBit(SIZE);
+       AuBit(ATIME);
+       AuBit(MTIME);
+       AuBit(CTIME);
+       AuBit(ATIME_SET);
+       AuBit(MTIME_SET);
+       AuBit(FORCE);
+       AuBit(ATTR_FLAG);
+       AuBit(KILL_SUID);
+       AuBit(KILL_SGID);
+       AuBit(FILE);
+       AuBit(KILL_PRIV);
+       AuBit(OPEN);
+       AuBit(TIMES_SET);
+#undef AuBit
+       dpri("ia_file %p\n", ia->ia_file);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_dbg_verify_dir_parent(struct dentry *dentry, unsigned int sigen)
+{
+       struct dentry *parent;
+
+       parent = dget_parent(dentry);
+       AuDebugOn(!S_ISDIR(dentry->d_inode->i_mode)
+                 || IS_ROOT(dentry)
+                 || au_digen(parent) != sigen);
+       dput(parent);
+}
+
+void au_dbg_verify_nondir_parent(struct dentry *dentry, unsigned int sigen)
+{
+       struct dentry *parent;
+
+       parent = dget_parent(dentry);
+       AuDebugOn(S_ISDIR(dentry->d_inode->i_mode)
+                 || au_digen(parent) != sigen);
+       dput(parent);
+}
+
+void au_dbg_verify_gen(struct dentry *parent, unsigned int sigen)
+{
+       int err, i, j;
+       struct au_dcsub_pages dpages;
+       struct au_dpage *dpage;
+       struct dentry **dentries;
+
+       err = au_dpages_init(&dpages, GFP_NOFS);
+       AuDebugOn(err);
+       err = au_dcsub_pages_rev(&dpages, parent, /*do_include*/1, NULL, NULL);
+       AuDebugOn(err);
+       for (i = dpages.ndpage - 1; !err && i >= 0; i--) {
+               dpage = dpages.dpages + i;
+               dentries = dpage->dentries;
+               for (j = dpage->ndentry - 1; !err && j >= 0; j--)
+                       AuDebugOn(au_digen(dentries[j]) != sigen);
+       }
+       au_dpages_free(&dpages);
+}
+
+void au_dbg_verify_hf(struct au_finfo *finfo)
+{
+       struct au_hfile *hf;
+       aufs_bindex_t bend, bindex;
+
+       if (finfo->fi_bstart >= 0) {
+               bend = finfo->fi_bend;
+               for (bindex = finfo->fi_bstart; bindex <= bend; bindex++) {
+                       hf = finfo->fi_hfile + bindex;
+                       AuDebugOn(hf->hf_file || hf->hf_br);
+               }
+       }
+}
+
+void au_dbg_verify_kthread(void)
+{
+       if (au_test_wkq(current)) {
+               au_dbg_blocked();
+               BUG();
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_debug_sbinfo_init(struct au_sbinfo *sbinfo __maybe_unused)
+{
+#ifdef AuForceNoPlink
+       au_opt_clr(sbinfo->si_mntflags, PLINK);
+#endif
+#ifdef AuForceNoXino
+       au_opt_clr(sbinfo->si_mntflags, XINO);
+#endif
+#ifdef AuForceNoRefrof
+       au_opt_clr(sbinfo->si_mntflags, REFROF);
+#endif
+#ifdef AuForceHinotify
+       au_opt_set_udba(sbinfo->si_mntflags, UDBA_HINOTIFY);
+#endif
+}
+
+int __init au_debug_init(void)
+{
+       aufs_bindex_t bindex;
+       struct au_vdir_destr destr;
+
+       bindex = -1;
+       AuDebugOn(bindex >= 0);
+
+       destr.len = -1;
+       AuDebugOn(destr.len < NAME_MAX);
+
+#ifdef CONFIG_4KSTACKS
+       AuWarn("CONFIG_4KSTACKS is defined.\n");
+#endif
+
+#ifdef AuForceNoBrs
+       sysaufs_brs = 0;
+#endif
+
+       return 0;
+}
diff --git a/fs/aufs/debug.h b/fs/aufs/debug.h
new file mode 100644
index 0000000..36ff0ea
--- /dev/null
+++ b/fs/aufs/debug.h
@@ -0,0 +1,243 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * debug print functions
+ */
+
+#ifndef __AUFS_DEBUG_H__
+#define __AUFS_DEBUG_H__
+
+#ifdef __KERNEL__
+
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/kd.h>
+#include <linux/vt_kern.h>
+#include <linux/sysrq.h>
+#include <linux/aufs_type.h>
+
+#ifdef CONFIG_AUFS_DEBUG
+#define AuDebugOn(a)           BUG_ON(a)
+
+/* module parameter */
+extern int aufs_debug;
+static inline void au_debug(int n)
+{
+       aufs_debug = n;
+       smp_mb();
+}
+
+static inline int au_debug_test(void)
+{
+       return aufs_debug;
+}
+#else
+#define AuDebugOn(a)           do {} while (0)
+#define au_debug()             do {} while (0)
+static inline int au_debug_test(void)
+{
+       return 0;
+}
+#endif /* CONFIG_AUFS_DEBUG */
+
+/* ---------------------------------------------------------------------- */
+
+/* debug print */
+
+#define AuDpri(lvl, fmt, arg...) \
+       printk(lvl AUFS_NAME " %s:%d:%s[%d]: " fmt, \
+              __func__, __LINE__, current->comm, current->pid, ##arg)
+#define AuDbg(fmt, arg...) do { \
+       if (au_debug_test()) \
+               AuDpri(KERN_DEBUG, fmt, ##arg); \
+} while (0)
+#define AuLabel(l)             AuDbg(#l "\n")
+#define AuInfo(fmt, arg...)    AuDpri(KERN_INFO, fmt, ##arg)
+#define AuWarn(fmt, arg...)    AuDpri(KERN_WARNING, fmt, ##arg)
+#define AuErr(fmt, arg...)     AuDpri(KERN_ERR, fmt, ##arg)
+#define AuIOErr(fmt, arg...)   AuErr("I/O Error, " fmt, ##arg)
+#define AuWarn1(fmt, arg...) do { \
+       static unsigned char _c; \
+       if (!_c++) \
+               AuWarn(fmt, ##arg); \
+} while (0)
+
+#define AuErr1(fmt, arg...) do { \
+       static unsigned char _c; \
+       if (!_c++) \
+               AuErr(fmt, ##arg); \
+} while (0)
+
+#define AuIOErr1(fmt, arg...) do { \
+       static unsigned char _c; \
+       if (!_c++) \
+               AuIOErr(fmt, ##arg); \
+} while (0)
+
+#define AuUnsupportMsg "This operation is not supported." \
+                       " Please report this application to aufs-users ML."
+#define AuUnsupport(fmt, args...) do { \
+       AuErr(AuUnsupportMsg "\n" fmt, ##args); \
+       dump_stack(); \
+} while (0)
+
+#define AuTraceErr(e) do { \
+       if (unlikely((e) < 0)) \
+               AuDbg("err %d\n", (int)(e)); \
+} while (0)
+
+#define AuTraceErrPtr(p) do { \
+       if (IS_ERR(p)) \
+               AuDbg("err %ld\n", PTR_ERR(p)); \
+} while (0)
+
+/* dirty macros for debug print, use with "%.*s" and caution */
+#define AuLNPair(qstr)         (qstr)->len, (qstr)->name
+#define AuDLNPair(d)           AuLNPair(&(d)->d_name)
+
+/* ---------------------------------------------------------------------- */
+
+struct au_sbinfo;
+struct au_finfo;
+#ifdef CONFIG_AUFS_DEBUG
+extern char *au_plevel;
+struct au_nhash;
+void au_dpri_whlist(struct au_nhash *whlist);
+struct au_vdir;
+void au_dpri_vdir(struct au_vdir *vdir);
+void au_dpri_inode(struct inode *inode);
+void au_dpri_dentry(struct dentry *dentry);
+void au_dpri_file(struct file *filp);
+void au_dpri_sb(struct super_block *sb);
+
+void au_dbg_sleep_jiffy(int jiffy);
+void au_dbg_iattr(struct iattr *ia);
+
+void au_dbg_verify_dir_parent(struct dentry *dentry, unsigned int sigen);
+void au_dbg_verify_nondir_parent(struct dentry *dentry, unsigned int sigen);
+void au_dbg_verify_gen(struct dentry *parent, unsigned int sigen);
+void au_dbg_verify_hf(struct au_finfo *finfo);
+void au_dbg_verify_kthread(void);
+
+int __init au_debug_init(void);
+void au_debug_sbinfo_init(struct au_sbinfo *sbinfo);
+#define AuDbgWhlist(w) do { \
+       AuDbg(#w "\n"); \
+       au_dpri_whlist(w); \
+} while (0)
+
+#define AuDbgVdir(v) do { \
+       AuDbg(#v "\n"); \
+       au_dpri_vdir(v); \
+} while (0)
+
+#define AuDbgInode(i) do { \
+       AuDbg(#i "\n"); \
+       au_dpri_inode(i); \
+} while (0)
+
+#define AuDbgDentry(d) do { \
+       AuDbg(#d "\n"); \
+       au_dpri_dentry(d); \
+} while (0)
+
+#define AuDbgFile(f) do { \
+       AuDbg(#f "\n"); \
+       au_dpri_file(f); \
+} while (0)
+
+#define AuDbgSb(sb) do { \
+       AuDbg(#sb "\n"); \
+       au_dpri_sb(sb); \
+} while (0)
+
+#define AuDbgSleep(sec) do { \
+       AuDbg("sleep %d sec\n", sec); \
+       ssleep(sec); \
+} while (0)
+
+#define AuDbgSleepJiffy(jiffy) do { \
+       AuDbg("sleep %d jiffies\n", jiffy); \
+       au_dbg_sleep_jiffy(jiffy); \
+} while (0)
+
+#define AuDbgIAttr(ia) do { \
+       AuDbg("ia_valid 0x%x\n", (ia)->ia_valid); \
+       au_dbg_iattr(ia); \
+} while (0)
+#else
+static inline void au_dbg_verify_dir_parent(struct dentry *dentry,
+                                           unsigned int sigen)
+{
+       /* empty */
+}
+static inline void au_dbg_verify_nondir_parent(struct dentry *dentry,
+                                          unsigned int sigen)
+{
+       /* empty */
+}
+static inline void au_dbg_verify_gen(struct dentry *parent, unsigned int sigen)
+{
+       /* empty */
+}
+static inline void au_dbg_verify_hf(struct au_finfo *finfo)
+{
+       /* empty */
+}
+static inline void au_dbg_verify_kthread(void)
+{
+       /* empty */
+}
+
+static inline int au_debug_init(void)
+{
+       return 0;
+}
+static inline void au_debug_sbinfo_init(struct au_sbinfo *sbinfo)
+{
+       /* empty */
+}
+#define AuDbgWhlist(w)         do {} while (0)
+#define AuDbgVdir(v)           do {} while (0)
+#define AuDbgInode(i)          do {} while (0)
+#define AuDbgDentry(d)         do {} while (0)
+#define AuDbgFile(f)           do {} while (0)
+#define AuDbgSb(sb)            do {} while (0)
+#define AuDbgSleep(sec)                do {} while (0)
+#define AuDbgSleepJiffy(jiffy) do {} while (0)
+#define AuDbgIAttr(ia)         do {} while (0)
+#endif /* CONFIG_AUFS_DEBUG */
+
+/* ---------------------------------------------------------------------- */
+
+#ifdef CONFIG_AUFS_MAGIC_SYSRQ
+int __init au_sysrq_init(void);
+void au_sysrq_fin(void);
+
+#ifdef CONFIG_HW_CONSOLE
+#define au_dbg_blocked() do { \
+       WARN_ON(1); \
+       handle_sysrq('w', vc_cons[fg_console].d->vc_tty); \
+} while (0)
+#else
+#define au_dbg_blocked()       do {} while (0)
+#endif
+
+#else
+static inline int au_sysrq_init(void)
+{
+       return 0;
+}
+#define au_sysrq_fin()         do {} while (0)
+#define au_dbg_blocked()       do {} while (0)
+#endif /* CONFIG_AUFS_MAGIC_SYSRQ */
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_DEBUG_H__ */
diff --git a/fs/aufs/dentry.c b/fs/aufs/dentry.c
new file mode 100644
index 0000000..f36956a
--- /dev/null
+++ b/fs/aufs/dentry.c
@@ -0,0 +1,858 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * lookup and dentry operations
+ */
+
+#include "aufs.h"
+
+static void au_h_nd(struct nameidata *h_nd, struct nameidata *nd)
+{
+       if (nd) {
+               *h_nd = *nd;
+
+               /*
+                * gave up supporting LOOKUP_CREATE/OPEN for lower fs,
+                * due to whiteout and branch permission.
+                */
+               h_nd->flags &= ~(/*LOOKUP_PARENT |*/ LOOKUP_OPEN | LOOKUP_CREATE
+                                | LOOKUP_FOLLOW);
+               /* unnecessary? */
+               h_nd->intent.open.file = NULL;
+       } else
+               memset(h_nd, 0, sizeof(*h_nd));
+}
+
+struct au_lkup_one_args {
+       struct dentry **errp;
+       struct qstr *name;
+       struct dentry *h_parent;
+       struct au_branch *br;
+       struct nameidata *nd;
+};
+
+struct dentry *au_lkup_one(struct qstr *name, struct dentry *h_parent,
+                          struct au_branch *br, struct nameidata *nd)
+{
+       struct dentry *h_dentry;
+       int err;
+       struct nameidata h_nd;
+
+       if (au_test_fs_null_nd(h_parent->d_sb))
+               return vfsub_lookup_one_len(name->name, h_parent, name->len);
+
+       au_h_nd(&h_nd, nd);
+       h_nd.path.dentry = h_parent;
+       h_nd.path.mnt = br->br_mnt;
+
+       err = __lookup_one_len(name->name, &h_nd.last, NULL, name->len);
+       h_dentry = ERR_PTR(err);
+       if (!err) {
+               path_get(&h_nd.path);
+               h_dentry = vfsub_lookup_hash(&h_nd);
+               path_put(&h_nd.path);
+       }
+
+       return h_dentry;
+}
+
+static void au_call_lkup_one(void *args)
+{
+       struct au_lkup_one_args *a = args;
+       *a->errp = au_lkup_one(a->name, a->h_parent, a->br, a->nd);
+}
+
+#define AuLkup_ALLOW_NEG       1
+#define au_ftest_lkup(flags, name)     ((flags) & AuLkup_##name)
+#define au_fset_lkup(flags, name)      { (flags) |= AuLkup_##name; }
+#define au_fclr_lkup(flags, name)      { (flags) &= ~AuLkup_##name; }
+
+struct au_do_lookup_args {
+       unsigned int            flags;
+       mode_t                  type;
+       struct nameidata        *nd;
+};
+
+/*
+ * returns positive/negative dentry, NULL or an error.
+ * NULL means whiteout-ed or not-found.
+ */
+static struct dentry*
+au_do_lookup(struct dentry *h_parent, struct dentry *dentry,
+            aufs_bindex_t bindex, struct qstr *wh_name,
+            struct au_do_lookup_args *args)
+{
+       struct dentry *h_dentry;
+       struct inode *h_inode, *inode;
+       struct qstr *name;
+       struct au_branch *br;
+       int wh_found, opq;
+       unsigned char wh_able;
+       const unsigned char allow_neg = !!au_ftest_lkup(args->flags, ALLOW_NEG);
+
+       name = &dentry->d_name;
+       wh_found = 0;
+       br = au_sbr(dentry->d_sb, bindex);
+       wh_able = !!au_br_whable(br->br_perm);
+       if (wh_able)
+               wh_found = au_wh_test(h_parent, wh_name, br, /*try_sio*/0);
+       h_dentry = ERR_PTR(wh_found);
+       if (!wh_found)
+               goto real_lookup;
+       if (unlikely(wh_found < 0))
+               goto out;
+
+       /* We found a whiteout */
+       /* au_set_dbend(dentry, bindex); */
+       au_set_dbwh(dentry, bindex);
+       if (!allow_neg)
+               return NULL; /* success */
+
+ real_lookup:
+       h_dentry = au_lkup_one(name, h_parent, br, args->nd);
+       if (IS_ERR(h_dentry))
+               goto out;
+
+       h_inode = h_dentry->d_inode;
+       if (!h_inode) {
+               if (!allow_neg)
+                       goto out_neg;
+       } else if (wh_found
+                  || (args->type && args->type != (h_inode->i_mode & S_IFMT)))
+               goto out_neg;
+
+       if (au_dbend(dentry) <= bindex)
+               au_set_dbend(dentry, bindex);
+       if (au_dbstart(dentry) < 0 || bindex < au_dbstart(dentry))
+               au_set_dbstart(dentry, bindex);
+       au_set_h_dptr(dentry, bindex, h_dentry);
+
+       inode = dentry->d_inode;
+       if (!h_inode || !S_ISDIR(h_inode->i_mode) || !wh_able
+           || (inode && !S_ISDIR(inode->i_mode)))
+               goto out; /* success */
+
+       mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+       opq = au_diropq_test(h_dentry, br);
+       mutex_unlock(&h_inode->i_mutex);
+       if (opq > 0)
+               au_set_dbdiropq(dentry, bindex);
+       else if (unlikely(opq < 0)) {
+               au_set_h_dptr(dentry, bindex, NULL);
+               h_dentry = ERR_PTR(opq);
+       }
+       goto out;
+
+ out_neg:
+       dput(h_dentry);
+       h_dentry = NULL;
+ out:
+       return h_dentry;
+}
+
+/*
+ * returns the number of lower positive dentries,
+ * otherwise an error.
+ * can be called at unlinking with @type is zero.
+ */
+int au_lkup_dentry(struct dentry *dentry, aufs_bindex_t bstart, mode_t type,
+                  struct nameidata *nd)
+{
+       int npositive, err;
+       aufs_bindex_t bindex, btail, bdiropq;
+       unsigned char isdir;
+       struct qstr whname;
+       struct au_do_lookup_args args = {
+               .flags  = 0,
+               .type   = type,
+               .nd     = nd
+       };
+       const struct qstr *name = &dentry->d_name;
+       struct dentry *parent;
+       struct inode *inode;
+
+       err = -EPERM;
+       parent = dget_parent(dentry);
+       if (unlikely(!strncmp(name->name, AUFS_WH_PFX, AUFS_WH_PFX_LEN)))
+               goto out;
+
+       err = au_wh_name_alloc(&whname, name);
+       if (unlikely(err))
+               goto out;
+
+       inode = dentry->d_inode;
+       isdir = !!(inode && S_ISDIR(inode->i_mode));
+       if (!type)
+               au_fset_lkup(args.flags, ALLOW_NEG);
+
+       npositive = 0;
+       btail = au_dbtaildir(parent);
+       for (bindex = bstart; bindex <= btail; bindex++) {
+               struct dentry *h_parent, *h_dentry;
+               struct inode *h_inode, *h_dir;
+
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (h_dentry) {
+                       if (h_dentry->d_inode)
+                               npositive++;
+                       if (type != S_IFDIR)
+                               break;
+                       continue;
+               }
+               h_parent = au_h_dptr(parent, bindex);
+               if (!h_parent)
+                       continue;
+               h_dir = h_parent->d_inode;
+               if (!h_dir || !S_ISDIR(h_dir->i_mode))
+                       continue;
+
+               mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_PARENT);
+               h_dentry = au_do_lookup(h_parent, dentry, bindex, &whname,
+                                       &args);
+               mutex_unlock(&h_dir->i_mutex);
+               err = PTR_ERR(h_dentry);
+               if (IS_ERR(h_dentry))
+                       goto out_wh;
+               au_fclr_lkup(args.flags, ALLOW_NEG);
+
+               if (au_dbwh(dentry) >= 0)
+                       break;
+               if (!h_dentry)
+                       continue;
+               h_inode = h_dentry->d_inode;
+               if (!h_inode)
+                       continue;
+               npositive++;
+               if (!args.type)
+                       args.type = h_inode->i_mode & S_IFMT;
+               if (args.type != S_IFDIR)
+                       break;
+               else if (isdir) {
+                       /* the type of lower may be different */
+                       bdiropq = au_dbdiropq(dentry);
+                       if (bdiropq >= 0 && bdiropq <= bindex)
+                               break;
+               }
+       }
+
+       if (npositive) {
+               AuLabel(positive);
+               au_update_dbstart(dentry);
+       }
+       err = npositive;
+       if (unlikely(!au_opt_test(au_mntflags(dentry->d_sb), UDBA_NONE)
+                    && au_dbstart(dentry) < 0))
+               /* both of real entry and whiteout found */
+               err = -EIO;
+
+ out_wh:
+       kfree(whname.name);
+ out:
+       dput(parent);
+       return err;
+}
+
+struct dentry *au_sio_lkup_one(struct qstr *name, struct dentry *parent,
+                              struct au_branch *br)
+{
+       struct dentry *dentry;
+       int wkq_err;
+
+       if (!au_test_h_perm_sio(parent->d_inode, MAY_EXEC))
+               dentry = au_lkup_one(name, parent, br, /*nd*/NULL);
+       else {
+               struct au_lkup_one_args args = {
+                       .errp           = &dentry,
+                       .name           = name,
+                       .h_parent       = parent,
+                       .br             = br,
+                       .nd             = NULL
+               };
+
+               wkq_err = au_wkq_wait(au_call_lkup_one, &args);
+               if (unlikely(wkq_err))
+                       dentry = ERR_PTR(wkq_err);
+       }
+
+       return dentry;
+}
+
+/*
+ * lookup @dentry on @bindex which should be negative.
+ */
+int au_lkup_neg(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       int err;
+       struct dentry *parent, *h_parent, *h_dentry;
+       struct qstr *name;
+
+       name = &dentry->d_name;
+       parent = dget_parent(dentry);
+       h_parent = au_h_dptr(parent, bindex);
+       h_dentry = au_sio_lkup_one(name, h_parent,
+                                  au_sbr(dentry->d_sb, bindex));
+       err = PTR_ERR(h_dentry);
+       if (IS_ERR(h_dentry))
+               goto out;
+       if (unlikely(h_dentry->d_inode)) {
+               err = -EIO;
+               AuIOErr("b%d %.*s should be negative.\n",
+                       bindex, AuDLNPair(h_dentry));
+               dput(h_dentry);
+               goto out;
+       }
+
+       if (bindex < au_dbstart(dentry))
+               au_set_dbstart(dentry, bindex);
+       if (au_dbend(dentry) < bindex)
+               au_set_dbend(dentry, bindex);
+       au_set_h_dptr(dentry, bindex, h_dentry);
+       err = 0;
+
+ out:
+       dput(parent);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* subset of struct inode */
+struct au_iattr {
+       unsigned long           i_ino;
+       /* unsigned int         i_nlink; */
+       uid_t                   i_uid;
+       gid_t                   i_gid;
+       u64                     i_version;
+/*
+       loff_t                  i_size;
+       blkcnt_t                i_blocks;
+*/
+       umode_t                 i_mode;
+};
+
+static void au_iattr_save(struct au_iattr *ia, struct inode *h_inode)
+{
+       ia->i_ino = h_inode->i_ino;
+       /* ia->i_nlink = h_inode->i_nlink; */
+       ia->i_uid = h_inode->i_uid;
+       ia->i_gid = h_inode->i_gid;
+       ia->i_version = h_inode->i_version;
+/*
+       ia->i_size = h_inode->i_size;
+       ia->i_blocks = h_inode->i_blocks;
+*/
+       ia->i_mode = (h_inode->i_mode & S_IFMT);
+}
+
+static int au_iattr_test(struct au_iattr *ia, struct inode *h_inode)
+{
+       return ia->i_ino != h_inode->i_ino
+               /* || ia->i_nlink != h_inode->i_nlink */
+               || ia->i_uid != h_inode->i_uid
+               || ia->i_gid != h_inode->i_gid
+               || ia->i_version != h_inode->i_version
+/*
+               || ia->i_size != h_inode->i_size
+               || ia->i_blocks != h_inode->i_blocks
+*/
+               || ia->i_mode != (h_inode->i_mode & S_IFMT);
+}
+
+static int au_h_verify_dentry(struct dentry *h_dentry, struct dentry *h_parent,
+                             struct au_branch *br)
+{
+       int err;
+       struct au_iattr ia;
+       struct inode *h_inode;
+       struct dentry *h_d;
+       struct super_block *h_sb;
+
+       err = 0;
+       memset(&ia, -1, sizeof(ia));
+       h_sb = h_dentry->d_sb;
+       h_inode = h_dentry->d_inode;
+       if (h_inode)
+               au_iattr_save(&ia, h_inode);
+       else if (au_test_nfs(h_sb) || au_test_fuse(h_sb))
+               /* nfs d_revalidate may return 0 for negative dentry */
+               /* fuse d_revalidate always return 0 for negative dentry */
+               goto out;
+
+       /* main purpose is namei.c:cached_lookup() and d_revalidate */
+       h_d = au_lkup_one(&h_dentry->d_name, h_parent, br, /*nd*/NULL);
+       err = PTR_ERR(h_d);
+       if (IS_ERR(h_d))
+               goto out;
+
+       err = 0;
+       if (unlikely(h_d != h_dentry
+                    || h_d->d_inode != h_inode
+                    || (h_inode && au_iattr_test(&ia, h_inode))))
+               err = au_busy_or_stale();
+       dput(h_d);
+
+ out:
+       AuTraceErr(err);
+       return err;
+}
+
+int au_h_verify(struct dentry *h_dentry, unsigned int udba, struct inode *h_dir,
+               struct dentry *h_parent, struct au_branch *br)
+{
+       int err;
+
+       err = 0;
+       if (udba == AuOpt_UDBA_REVAL) {
+               IMustLock(h_dir);
+               err = (h_dentry->d_parent->d_inode != h_dir);
+       } else if (udba == AuOpt_UDBA_HINOTIFY)
+               err = au_h_verify_dentry(h_dentry, h_parent, br);
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void au_do_refresh_hdentry(struct au_hdentry *p, struct au_dinfo *dinfo,
+                                 struct dentry *parent)
+{
+       struct dentry *h_d, *h_dp;
+       struct au_hdentry tmp, *q;
+       struct super_block *sb;
+       aufs_bindex_t new_bindex, bindex, bend, bwh, bdiropq;
+
+       bend = dinfo->di_bend;
+       bwh = dinfo->di_bwh;
+       bdiropq = dinfo->di_bdiropq;
+       for (bindex = dinfo->di_bstart; bindex <= bend; bindex++, p++) {
+               h_d = p->hd_dentry;
+               if (!h_d)
+                       continue;
+
+               h_dp = dget_parent(h_d);
+               if (h_dp == au_h_dptr(parent, bindex)) {
+                       dput(h_dp);
+                       continue;
+               }
+
+               new_bindex = au_find_dbindex(parent, h_dp);
+               dput(h_dp);
+               if (dinfo->di_bwh == bindex)
+                       bwh = new_bindex;
+               if (dinfo->di_bdiropq == bindex)
+                       bdiropq = new_bindex;
+               if (new_bindex < 0) {
+                       au_hdput(p);
+                       p->hd_dentry = NULL;
+                       continue;
+               }
+
+               /* swap two lower dentries, and loop again */
+               q = dinfo->di_hdentry + new_bindex;
+               tmp = *q;
+               *q = *p;
+               *p = tmp;
+               if (tmp.hd_dentry) {
+                       bindex--;
+                       p--;
+               }
+       }
+
+       sb = parent->d_sb;
+       dinfo->di_bwh = -1;
+       if (bwh >= 0 && bwh <= au_sbend(sb) && au_sbr_whable(sb, bwh))
+               dinfo->di_bwh = bwh;
+
+       dinfo->di_bdiropq = -1;
+       if (bdiropq >= 0
+           && bdiropq <= au_sbend(sb)
+           && au_sbr_whable(sb, bdiropq))
+               dinfo->di_bdiropq = bdiropq;
+
+       bend = au_dbend(parent);
+       p = dinfo->di_hdentry;
+       for (bindex = 0; bindex <= bend; bindex++, p++)
+               if (p->hd_dentry) {
+                       dinfo->di_bstart = bindex;
+                       break;
+               }
+
+       p = dinfo->di_hdentry + bend;
+       for (bindex = bend; bindex >= 0; bindex--, p--)
+               if (p->hd_dentry) {
+                       dinfo->di_bend = bindex;
+                       break;
+               }
+}
+
+/*
+ * returns the number of found lower positive dentries,
+ * otherwise an error.
+ */
+int au_refresh_hdentry(struct dentry *dentry, mode_t type)
+{
+       int npositive, err;
+       unsigned int sigen;
+       aufs_bindex_t bstart;
+       struct au_dinfo *dinfo;
+       struct super_block *sb;
+       struct dentry *parent;
+
+       sb = dentry->d_sb;
+       AuDebugOn(IS_ROOT(dentry));
+       sigen = au_sigen(sb);
+       parent = dget_parent(dentry);
+       AuDebugOn(au_digen(parent) != sigen
+                 || au_iigen(parent->d_inode) != sigen);
+
+       dinfo = au_di(dentry);
+       err = au_di_realloc(dinfo, au_sbend(sb) + 1);
+       npositive = err;
+       if (unlikely(err))
+               goto out;
+       au_do_refresh_hdentry(dinfo->di_hdentry + dinfo->di_bstart, dinfo,
+                             parent);
+
+       npositive = 0;
+       bstart = au_dbstart(parent);
+       if (type != S_IFDIR && dinfo->di_bstart == bstart)
+               goto out_dgen; /* success */
+
+       npositive = au_lkup_dentry(dentry, bstart, type, /*nd*/NULL);
+       if (npositive < 0)
+               goto out;
+       if (dinfo->di_bwh >= 0 && dinfo->di_bwh <= dinfo->di_bstart)
+               d_drop(dentry);
+
+ out_dgen:
+       au_update_digen(dentry);
+ out:
+       dput(parent);
+       AuTraceErr(npositive);
+       return npositive;
+}
+
+static noinline_for_stack
+int au_do_h_d_reval(struct dentry *h_dentry, struct nameidata *nd,
+                   struct dentry *dentry, aufs_bindex_t bindex)
+{
+       int err, valid;
+       int (*reval)(struct dentry *, struct nameidata *);
+
+       err = 0;
+       reval = NULL;
+       if (h_dentry->d_op)
+               reval = h_dentry->d_op->d_revalidate;
+       if (!reval)
+               goto out;
+
+       AuDbg("b%d\n", bindex);
+       if (au_test_fs_null_nd(h_dentry->d_sb))
+               /* it may return tri-state */
+               valid = reval(h_dentry, NULL);
+       else {
+               struct nameidata h_nd;
+               int locked;
+               struct dentry *parent;
+
+               au_h_nd(&h_nd, nd);
+               parent = nd->path.dentry;
+               locked = (nd && nd->path.dentry != dentry);
+               if (locked)
+                       di_read_lock_parent(parent, AuLock_IR);
+               BUG_ON(bindex > au_dbend(parent));
+               h_nd.path.dentry = au_h_dptr(parent, bindex);
+               BUG_ON(!h_nd.path.dentry);
+               h_nd.path.mnt = au_sbr(parent->d_sb, bindex)->br_mnt;
+               path_get(&h_nd.path);
+               valid = reval(h_dentry, &h_nd);
+               path_put(&h_nd.path);
+               if (locked)
+                       di_read_unlock(parent, AuLock_IR);
+       }
+
+       if (unlikely(valid < 0))
+               err = valid;
+       else if (!valid)
+               err = -EINVAL;
+
+ out:
+       AuTraceErr(err);
+       return err;
+}
+
+/* todo: remove this */
+static int h_d_revalidate(struct dentry *dentry, struct inode *inode,
+                         struct nameidata *nd, int do_udba)
+{
+       int err;
+       umode_t mode, h_mode;
+       aufs_bindex_t bindex, btail, bstart, ibs, ibe;
+       unsigned char plus, unhashed, is_root, h_plus;
+       struct inode *first, *h_inode, *h_cached_inode;
+       struct dentry *h_dentry;
+       struct qstr *name, *h_name;
+
+       err = 0;
+       plus = 0;
+       mode = 0;
+       first = NULL;
+       ibs = -1;
+       ibe = -1;
+       unhashed = !!d_unhashed(dentry);
+       is_root = !!IS_ROOT(dentry);
+       name = &dentry->d_name;
+
+       /*
+        * Theoretically, REVAL test should be unnecessary in case of INOTIFY.
+        * But inotify doesn't fire some necessary events,
+        *      IN_ATTRIB for atime/nlink/pageio
+        *      IN_DELETE for NFS dentry
+        * Let's do REVAL test too.
+        */
+       if (do_udba && inode) {
+               mode = (inode->i_mode & S_IFMT);
+               plus = (inode->i_nlink > 0);
+               first = au_h_iptr(inode, au_ibstart(inode));
+               ibs = au_ibstart(inode);
+               ibe = au_ibend(inode);
+       }
+
+       bstart = au_dbstart(dentry);
+       btail = bstart;
+       if (inode && S_ISDIR(inode->i_mode))
+               btail = au_dbtaildir(dentry);
+       for (bindex = bstart; bindex <= btail; bindex++) {
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (!h_dentry)
+                       continue;
+
+               AuDbg("b%d, %.*s\n", bindex, AuDLNPair(h_dentry));
+               h_name = &h_dentry->d_name;
+               if (unlikely(do_udba
+                            && !is_root
+                            && (unhashed != !!d_unhashed(h_dentry)
+                                || name->len != h_name->len
+                                || memcmp(name->name, h_name->name, name->len))
+                           )) {
+                       AuDbg("unhash 0x%x 0x%x, %.*s %.*s\n",
+                                 unhashed, d_unhashed(h_dentry),
+                                 AuDLNPair(dentry), AuDLNPair(h_dentry));
+                       goto err;
+               }
+
+               err = au_do_h_d_reval(h_dentry, nd, dentry, bindex);
+               if (unlikely(err))
+                       /* do not goto err, to keep the errno */
+                       break;
+
+               /* todo: plink too? */
+               if (!do_udba)
+                       continue;
+
+               /* UDBA tests */
+               h_inode = h_dentry->d_inode;
+               if (unlikely(!!inode != !!h_inode))
+                       goto err;
+
+               h_plus = plus;
+               h_mode = mode;
+               h_cached_inode = h_inode;
+               if (h_inode) {
+                       h_mode = (h_inode->i_mode & S_IFMT);
+                       h_plus = (h_inode->i_nlink > 0);
+               }
+               if (inode && ibs <= bindex && bindex <= ibe)
+                       h_cached_inode = au_h_iptr(inode, bindex);
+
+               if (unlikely(plus != h_plus
+                            || mode != h_mode
+                            || h_cached_inode != h_inode))
+                       goto err;
+               continue;
+
+       err:
+               err = -EINVAL;
+               break;
+       }
+
+       return err;
+}
+
+static int simple_reval_dpath(struct dentry *dentry, unsigned int sigen)
+{
+       int err;
+       struct dentry *parent;
+       struct inode *inode;
+
+       inode = dentry->d_inode;
+       if (au_digen(dentry) == sigen && au_iigen(inode) == sigen)
+               return 0;
+
+       parent = dget_parent(dentry);
+       di_read_lock_parent(parent, AuLock_IR);
+       AuDebugOn(au_digen(parent) != sigen
+                 || au_iigen(parent->d_inode) != sigen);
+       au_dbg_verify_gen(parent, sigen);
+
+       /* returns a number of positive dentries */
+       err = au_refresh_hdentry(dentry, inode->i_mode & S_IFMT);
+       if (err >= 0)
+               err = au_refresh_hinode(inode, dentry);
+
+       di_read_unlock(parent, AuLock_IR);
+       dput(parent);
+       return err;
+}
+
+int au_reval_dpath(struct dentry *dentry, unsigned int sigen)
+{
+       int err;
+       struct dentry *d, *parent;
+       struct inode *inode;
+
+       if (!au_ftest_si(au_sbi(dentry->d_sb), FAILED_REFRESH_DIRS))
+               return simple_reval_dpath(dentry, sigen);
+
+       /* slow loop, keep it simple and stupid */
+       /* cf: au_cpup_dirs() */
+       err = 0;
+       parent = NULL;
+       while (au_digen(dentry) != sigen
+              || au_iigen(dentry->d_inode) != sigen) {
+               d = dentry;
+               while (1) {
+                       dput(parent);
+                       parent = dget_parent(d);
+                       if (au_digen(parent) == sigen
+                           && au_iigen(parent->d_inode) == sigen)
+                               break;
+                       d = parent;
+               }
+
+               inode = d->d_inode;
+               if (d != dentry)
+                       di_write_lock_child(d);
+
+               /* someone might update our dentry while we were sleeping */
+               if (au_digen(d) != sigen || au_iigen(d->d_inode) != sigen) {
+                       di_read_lock_parent(parent, AuLock_IR);
+                       /* returns a number of positive dentries */
+                       err = au_refresh_hdentry(d, inode->i_mode & S_IFMT);
+                       if (err >= 0)
+                               err = au_refresh_hinode(inode, d);
+                       di_read_unlock(parent, AuLock_IR);
+               }
+
+               if (d != dentry)
+                       di_write_unlock(d);
+               dput(parent);
+               if (unlikely(err))
+                       break;
+       }
+
+       return err;
+}
+
+/*
+ * if valid returns 1, otherwise 0.
+ */
+static int aufs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+       int valid, err;
+       unsigned int sigen;
+       unsigned char do_udba;
+       struct super_block *sb;
+       struct inode *inode;
+
+       err = -EINVAL;
+       sb = dentry->d_sb;
+       inode = dentry->d_inode;
+       aufs_read_lock(dentry, AuLock_FLUSH | AuLock_DW);
+       sigen = au_sigen(sb);
+       if (au_digen(dentry) != sigen) {
+               AuDebugOn(IS_ROOT(dentry));
+               if (inode)
+                       err = au_reval_dpath(dentry, sigen);
+               if (unlikely(err))
+                       goto out_dgrade;
+               AuDebugOn(au_digen(dentry) != sigen);
+       }
+       if (inode && au_iigen(inode) != sigen) {
+               AuDebugOn(IS_ROOT(dentry));
+               err = au_refresh_hinode(inode, dentry);
+               if (unlikely(err))
+                       goto out_dgrade;
+               AuDebugOn(au_iigen(inode) != sigen);
+       }
+       di_downgrade_lock(dentry, AuLock_IR);
+
+       AuDebugOn(au_digen(dentry) != sigen);
+       AuDebugOn(inode && au_iigen(inode) != sigen);
+       err = -EINVAL;
+       do_udba = !au_opt_test(au_mntflags(sb), UDBA_NONE);
+       if (do_udba && inode) {
+               aufs_bindex_t bstart = au_ibstart(inode);
+
+               if (bstart >= 0
+                   && au_test_higen(inode, au_h_iptr(inode, bstart)))
+                       goto out;
+       }
+
+       err = h_d_revalidate(dentry, inode, nd, do_udba);
+       if (unlikely(!err && do_udba && au_dbstart(dentry) < 0))
+               /* both of real entry and whiteout found */
+               err = -EIO;
+       goto out;
+
+ out_dgrade:
+       di_downgrade_lock(dentry, AuLock_IR);
+ out:
+       au_store_oflag(nd, inode);
+       aufs_read_unlock(dentry, AuLock_IR);
+       AuTraceErr(err);
+       valid = !err;
+       if (!valid)
+               AuDbg("%.*s invalid\n", AuDLNPair(dentry));
+       return valid;
+}
+
+static void aufs_d_release(struct dentry *dentry)
+{
+       struct au_dinfo *dinfo;
+       aufs_bindex_t bend, bindex;
+
+       dinfo = dentry->d_fsdata;
+       if (!dinfo)
+               return;
+
+       /* dentry may not be revalidated */
+       bindex = dinfo->di_bstart;
+       if (bindex >= 0) {
+               struct au_hdentry *p;
+
+               bend = dinfo->di_bend;
+               p = dinfo->di_hdentry + bindex;
+               while (bindex++ <= bend) {
+                       if (p->hd_dentry)
+                               au_hdput(p);
+                       p++;
+               }
+       }
+       kfree(dinfo->di_hdentry);
+       au_rwsem_destroy(&dinfo->di_rwsem);
+       au_cache_free_dinfo(dinfo);
+       au_hin_di_reinit(dentry);
+}
+
+struct dentry_operations aufs_dop = {
+       .d_revalidate   = aufs_d_revalidate,
+       .d_release      = aufs_d_release
+};
diff --git a/fs/aufs/dentry.h b/fs/aufs/dentry.h
new file mode 100644
index 0000000..8708db8
--- /dev/null
+++ b/fs/aufs/dentry.h
@@ -0,0 +1,213 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * lookup and dentry operations
+ */
+
+#ifndef __AUFS_DENTRY_H__
+#define __AUFS_DENTRY_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/aufs_type.h>
+#include "rwsem.h"
+
+/* make a single member structure for future use */
+/* todo: remove this structure */
+struct au_hdentry {
+       struct dentry           *hd_dentry;
+};
+
+struct au_dinfo {
+       atomic_t                di_generation;
+
+       struct rw_semaphore     di_rwsem;
+       aufs_bindex_t           di_bstart, di_bend, di_bwh, di_bdiropq;
+       struct au_hdentry       *di_hdentry;
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* dentry.c */
+extern struct dentry_operations aufs_dop;
+struct au_branch;
+struct dentry *au_lkup_one(struct qstr *name, struct dentry *h_parent,
+                          struct au_branch *br, struct nameidata *nd);
+struct dentry *au_sio_lkup_one(struct qstr *name, struct dentry *parent,
+                              struct au_branch *br);
+int au_h_verify(struct dentry *h_dentry, unsigned int udba, struct inode *h_dir,
+               struct dentry *h_parent, struct au_branch *br);
+
+int au_lkup_dentry(struct dentry *dentry, aufs_bindex_t bstart, mode_t type,
+                  struct nameidata *nd);
+int au_lkup_neg(struct dentry *dentry, aufs_bindex_t bindex);
+int au_refresh_hdentry(struct dentry *dentry, mode_t type);
+int au_reval_dpath(struct dentry *dentry, unsigned int sigen);
+
+/* dinfo.c */
+int au_alloc_dinfo(struct dentry *dentry);
+int au_di_realloc(struct au_dinfo *dinfo, int nbr);
+
+void di_read_lock(struct dentry *d, int flags, unsigned int lsc);
+void di_read_unlock(struct dentry *d, int flags);
+void di_downgrade_lock(struct dentry *d, int flags);
+void di_write_lock(struct dentry *d, unsigned int lsc);
+void di_write_unlock(struct dentry *d);
+void di_write_lock2_child(struct dentry *d1, struct dentry *d2, int isdir);
+void di_write_lock2_parent(struct dentry *d1, struct dentry *d2, int isdir);
+void di_write_unlock2(struct dentry *d1, struct dentry *d2);
+
+struct dentry *au_h_dptr(struct dentry *dentry, aufs_bindex_t bindex);
+aufs_bindex_t au_dbtail(struct dentry *dentry);
+aufs_bindex_t au_dbtaildir(struct dentry *dentry);
+
+void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
+                  struct dentry *h_dentry);
+void au_update_digen(struct dentry *dentry);
+void au_update_dbrange(struct dentry *dentry, int do_put_zero);
+void au_update_dbstart(struct dentry *dentry);
+void au_update_dbend(struct dentry *dentry);
+int au_find_dbindex(struct dentry *dentry, struct dentry *h_dentry);
+
+/* ---------------------------------------------------------------------- */
+
+static inline struct au_dinfo *au_di(struct dentry *dentry)
+{
+       return dentry->d_fsdata;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* lock subclass for dinfo */
+enum {
+       AuLsc_DI_CHILD,         /* child first */
+       AuLsc_DI_CHILD2,        /* rename(2), link(2), and cpup at hinotify */
+       AuLsc_DI_CHILD3,        /* copyup dirs */
+       AuLsc_DI_PARENT,
+       AuLsc_DI_PARENT2,
+       AuLsc_DI_PARENT3
+};
+
+/*
+ * di_read_lock_child, di_write_lock_child,
+ * di_read_lock_child2, di_write_lock_child2,
+ * di_read_lock_child3, di_write_lock_child3,
+ * di_read_lock_parent, di_write_lock_parent,
+ * di_read_lock_parent2, di_write_lock_parent2,
+ * di_read_lock_parent3, di_write_lock_parent3,
+ */
+#define AuReadLockFunc(name, lsc) \
+static inline void di_read_lock_##name(struct dentry *d, int flags) \
+{ di_read_lock(d, flags, AuLsc_DI_##lsc); }
+
+#define AuWriteLockFunc(name, lsc) \
+static inline void di_write_lock_##name(struct dentry *d) \
+{ di_write_lock(d, AuLsc_DI_##lsc); }
+
+#define AuRWLockFuncs(name, lsc) \
+       AuReadLockFunc(name, lsc) \
+       AuWriteLockFunc(name, lsc)
+
+AuRWLockFuncs(child, CHILD);
+AuRWLockFuncs(child2, CHILD2);
+AuRWLockFuncs(child3, CHILD3);
+AuRWLockFuncs(parent, PARENT);
+AuRWLockFuncs(parent2, PARENT2);
+AuRWLockFuncs(parent3, PARENT3);
+
+#undef AuReadLockFunc
+#undef AuWriteLockFunc
+#undef AuRWLockFuncs
+
+#define DiMustNoWaiters(d)     AuRwMustNoWaiters(&au_di(d)->di_rwsem)
+
+/* ---------------------------------------------------------------------- */
+
+/* todo: memory barrier? */
+static inline unsigned int au_digen(struct dentry *d)
+{
+       return atomic_read(&au_di(d)->di_generation);
+}
+
+static inline void au_h_dentry_init(struct au_hdentry *hdentry)
+{
+       hdentry->hd_dentry = NULL;
+}
+
+static inline void au_hdput(struct au_hdentry *hd)
+{
+       dput(hd->hd_dentry);
+}
+
+static inline aufs_bindex_t au_dbstart(struct dentry *dentry)
+{
+       return au_di(dentry)->di_bstart;
+}
+
+static inline aufs_bindex_t au_dbend(struct dentry *dentry)
+{
+       return au_di(dentry)->di_bend;
+}
+
+static inline aufs_bindex_t au_dbwh(struct dentry *dentry)
+{
+       return au_di(dentry)->di_bwh;
+}
+
+static inline aufs_bindex_t au_dbdiropq(struct dentry *dentry)
+{
+       return au_di(dentry)->di_bdiropq;
+}
+
+/* todo: hard/soft set? */
+static inline void au_set_dbstart(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       au_di(dentry)->di_bstart = bindex;
+}
+
+static inline void au_set_dbend(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       au_di(dentry)->di_bend = bindex;
+}
+
+static inline void au_set_dbwh(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       /* dbwh can be outside of bstart - bend range */
+       au_di(dentry)->di_bwh = bindex;
+}
+
+static inline void au_set_dbdiropq(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       au_di(dentry)->di_bdiropq = bindex;
+}
+
+/* ---------------------------------------------------------------------- */
+
+#ifdef CONFIG_AUFS_HINOTIFY
+static inline void au_digen_dec(struct dentry *d)
+{
+       atomic_dec(&au_di(d)->di_generation);
+}
+
+static inline void au_hin_di_reinit(struct dentry *dentry)
+{
+       dentry->d_fsdata = NULL;
+}
+#else
+static inline void au_hin_di_reinit(struct dentry *dentry __maybe_unused)
+{
+       /* empty */
+}
+#endif /* CONFIG_AUFS_HINOTIFY */
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_DENTRY_H__ */
diff --git a/fs/aufs/dinfo.c b/fs/aufs/dinfo.c
new file mode 100644
index 0000000..b0645aa
--- /dev/null
+++ b/fs/aufs/dinfo.c
@@ -0,0 +1,351 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * dentry private data
+ */
+
+#include "aufs.h"
+
+int au_alloc_dinfo(struct dentry *dentry)
+{
+       struct au_dinfo *dinfo;
+       struct super_block *sb;
+       int nbr;
+
+       dinfo = au_cache_alloc_dinfo();
+       if (unlikely(!dinfo))
+               goto out;
+
+       sb = dentry->d_sb;
+       nbr = au_sbend(sb) + 1;
+       if (nbr <= 0)
+               nbr = 1;
+       dinfo->di_hdentry = kcalloc(nbr, sizeof(*dinfo->di_hdentry), GFP_NOFS);
+       if (unlikely(!dinfo->di_hdentry))
+               goto out_dinfo;
+
+       atomic_set(&dinfo->di_generation, au_sigen(sb));
+       /* smp_mb(); */ /* atomic_set */
+       init_rwsem(&dinfo->di_rwsem);
+       down_write_nested(&dinfo->di_rwsem, AuLsc_DI_CHILD);
+       dinfo->di_bstart = -1;
+       dinfo->di_bend = -1;
+       dinfo->di_bwh = -1;
+       dinfo->di_bdiropq = -1;
+
+       dentry->d_fsdata = dinfo;
+       dentry->d_op = &aufs_dop;
+       return 0; /* success */
+
+ out_dinfo:
+       au_cache_free_dinfo(dinfo);
+ out:
+       return -ENOMEM;
+}
+
+int au_di_realloc(struct au_dinfo *dinfo, int nbr)
+{
+       int err, sz;
+       struct au_hdentry *hdp;
+
+       err = -ENOMEM;
+       sz = sizeof(*hdp) * (dinfo->di_bend + 1);
+       if (!sz)
+               sz = sizeof(*hdp);
+       hdp = au_kzrealloc(dinfo->di_hdentry, sz, sizeof(*hdp) * nbr, GFP_NOFS);
+       if (hdp) {
+               dinfo->di_hdentry = hdp;
+               err = 0;
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void do_ii_write_lock(struct inode *inode, unsigned int lsc)
+{
+       switch (lsc) {
+       case AuLsc_DI_CHILD:
+               ii_write_lock_child(inode);
+               break;
+       case AuLsc_DI_CHILD2:
+               ii_write_lock_child2(inode);
+               break;
+       case AuLsc_DI_CHILD3:
+               ii_write_lock_child3(inode);
+               break;
+       case AuLsc_DI_PARENT:
+               ii_write_lock_parent(inode);
+               break;
+       case AuLsc_DI_PARENT2:
+               ii_write_lock_parent2(inode);
+               break;
+       case AuLsc_DI_PARENT3:
+               ii_write_lock_parent3(inode);
+               break;
+       default:
+               BUG();
+       }
+}
+
+static void do_ii_read_lock(struct inode *inode, unsigned int lsc)
+{
+       switch (lsc) {
+       case AuLsc_DI_CHILD:
+               ii_read_lock_child(inode);
+               break;
+       case AuLsc_DI_CHILD2:
+               ii_read_lock_child2(inode);
+               break;
+       case AuLsc_DI_CHILD3:
+               ii_read_lock_child3(inode);
+               break;
+       case AuLsc_DI_PARENT:
+               ii_read_lock_parent(inode);
+               break;
+       case AuLsc_DI_PARENT2:
+               ii_read_lock_parent2(inode);
+               break;
+       case AuLsc_DI_PARENT3:
+               ii_read_lock_parent3(inode);
+               break;
+       default:
+               BUG();
+       }
+}
+
+void di_read_lock(struct dentry *d, int flags, unsigned int lsc)
+{
+       down_read_nested(&au_di(d)->di_rwsem, lsc);
+       if (d->d_inode) {
+               if (au_ftest_lock(flags, IW))
+                       do_ii_write_lock(d->d_inode, lsc);
+               else if (au_ftest_lock(flags, IR))
+                       do_ii_read_lock(d->d_inode, lsc);
+       }
+}
+
+void di_read_unlock(struct dentry *d, int flags)
+{
+       if (d->d_inode) {
+               if (au_ftest_lock(flags, IW))
+                       ii_write_unlock(d->d_inode);
+               else if (au_ftest_lock(flags, IR))
+                       ii_read_unlock(d->d_inode);
+       }
+       up_read(&au_di(d)->di_rwsem);
+}
+
+void di_downgrade_lock(struct dentry *d, int flags)
+{
+       downgrade_write(&au_di(d)->di_rwsem);
+       if (d->d_inode && au_ftest_lock(flags, IR))
+               ii_downgrade_lock(d->d_inode);
+}
+
+void di_write_lock(struct dentry *d, unsigned int lsc)
+{
+       down_write_nested(&au_di(d)->di_rwsem, lsc);
+       if (d->d_inode)
+               do_ii_write_lock(d->d_inode, lsc);
+}
+
+void di_write_unlock(struct dentry *d)
+{
+       if (d->d_inode)
+               ii_write_unlock(d->d_inode);
+       up_write(&au_di(d)->di_rwsem);
+}
+
+void di_write_lock2_child(struct dentry *d1, struct dentry *d2, int isdir)
+{
+       AuDebugOn(d1 == d2
+                 || d1->d_inode == d2->d_inode
+                 || d1->d_sb != d2->d_sb);
+
+       if (isdir && au_test_subdir(d1, d2)) {
+               di_write_lock_child(d1);
+               di_write_lock_child2(d2);
+       } else {
+               /* there should be no races */
+               di_write_lock_child(d2);
+               di_write_lock_child2(d1);
+       }
+}
+
+void di_write_lock2_parent(struct dentry *d1, struct dentry *d2, int isdir)
+{
+       AuDebugOn(d1 == d2
+                 || d1->d_inode == d2->d_inode
+                 || d1->d_sb != d2->d_sb);
+
+       if (isdir && au_test_subdir(d1, d2)) {
+               di_write_lock_parent(d1);
+               di_write_lock_parent2(d2);
+       } else {
+               /* there should be no races */
+               di_write_lock_parent(d2);
+               di_write_lock_parent2(d1);
+       }
+}
+
+void di_write_unlock2(struct dentry *d1, struct dentry *d2)
+{
+       di_write_unlock(d1);
+       if (d1->d_inode == d2->d_inode)
+               up_write(&au_di(d2)->di_rwsem);
+       else
+               di_write_unlock(d2);
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct dentry *au_h_dptr(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       struct dentry *d;
+
+       if (au_dbstart(dentry) < 0 || bindex < au_dbstart(dentry))
+               return NULL;
+       AuDebugOn(bindex < 0);
+       d = au_di(dentry)->di_hdentry[0 + bindex].hd_dentry;
+       AuDebugOn(d && (atomic_read(&d->d_count) <= 0));
+       return d;
+}
+
+aufs_bindex_t au_dbtail(struct dentry *dentry)
+{
+       aufs_bindex_t bend, bwh;
+
+       bend = au_dbend(dentry);
+       if (0 <= bend) {
+               bwh = au_dbwh(dentry);
+               if (!bwh)
+                       return bwh;
+               if (0 < bwh && bwh < bend)
+                       return bwh - 1;
+       }
+       return bend;
+}
+
+aufs_bindex_t au_dbtaildir(struct dentry *dentry)
+{
+       aufs_bindex_t bend, bopq;
+
+       bend = au_dbtail(dentry);
+       if (0 <= bend) {
+               bopq = au_dbdiropq(dentry);
+               if (0 <= bopq && bopq < bend)
+                       bend = bopq;
+       }
+       return bend;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
+                  struct dentry *h_dentry)
+{
+       struct au_hdentry *hd = au_di(dentry)->di_hdentry + bindex;
+
+       if (hd->hd_dentry)
+               au_hdput(hd);
+       hd->hd_dentry = h_dentry;
+}
+
+void au_update_digen(struct dentry *dentry)
+{
+       atomic_set(&au_di(dentry)->di_generation, au_sigen(dentry->d_sb));
+       /* smp_mb(); */ /* atomic_set */
+}
+
+void au_update_dbrange(struct dentry *dentry, int do_put_zero)
+{
+       struct au_dinfo *dinfo;
+       struct dentry *h_d;
+
+       dinfo = au_di(dentry);
+       if (!dinfo || dinfo->di_bstart < 0)
+               return;
+
+       if (do_put_zero) {
+               aufs_bindex_t bindex, bend;
+
+               bend = dinfo->di_bend;
+               for (bindex = dinfo->di_bstart; bindex <= bend; bindex++) {
+                       h_d = dinfo->di_hdentry[0 + bindex].hd_dentry;
+                       if (h_d && !h_d->d_inode)
+                               au_set_h_dptr(dentry, bindex, NULL);
+               }
+       }
+
+       dinfo->di_bstart = -1;
+       while (++dinfo->di_bstart <= dinfo->di_bend)
+               if (dinfo->di_hdentry[0 + dinfo->di_bstart].hd_dentry)
+                       break;
+       if (dinfo->di_bstart > dinfo->di_bend) {
+               dinfo->di_bstart = -1;
+               dinfo->di_bend = -1;
+               return;
+       }
+
+       dinfo->di_bend++;
+       while (0 <= --dinfo->di_bend)
+               if (dinfo->di_hdentry[0 + dinfo->di_bend].hd_dentry)
+                       break;
+       AuDebugOn(dinfo->di_bstart > dinfo->di_bend || dinfo->di_bend < 0);
+}
+
+void au_update_dbstart(struct dentry *dentry)
+{
+       aufs_bindex_t bindex, bend;
+       struct dentry *h_dentry;
+
+       bend = au_dbend(dentry);
+       for (bindex = au_dbstart(dentry); bindex <= bend; bindex++) {
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (!h_dentry)
+                       continue;
+               if (h_dentry->d_inode) {
+                       au_set_dbstart(dentry, bindex);
+                       return;
+               }
+               au_set_h_dptr(dentry, bindex, NULL);
+       }
+}
+
+void au_update_dbend(struct dentry *dentry)
+{
+       aufs_bindex_t bindex, bstart;
+       struct dentry *h_dentry;
+
+       bstart = au_dbstart(dentry);
+       for (bindex = au_dbend(dentry); bindex <= bstart; bindex--) {
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (!h_dentry)
+                       continue;
+               if (h_dentry->d_inode) {
+                       au_set_dbend(dentry, bindex);
+                       return;
+               }
+               au_set_h_dptr(dentry, bindex, NULL);
+       }
+}
+
+int au_find_dbindex(struct dentry *dentry, struct dentry *h_dentry)
+{
+       aufs_bindex_t bindex, bend;
+
+       bend = au_dbend(dentry);
+       for (bindex = au_dbstart(dentry); bindex <= bend; bindex++)
+               if (au_h_dptr(dentry, bindex) == h_dentry)
+                       return bindex;
+       return -1;
+}
diff --git a/fs/aufs/dir.c b/fs/aufs/dir.c
new file mode 100644
index 0000000..9fc6196
--- /dev/null
+++ b/fs/aufs/dir.c
@@ -0,0 +1,513 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * directory operations
+ */
+
+#include <linux/fs_stack.h>
+#include "aufs.h"
+
+void au_add_nlink(struct inode *dir, struct inode *h_dir)
+{
+       AuDebugOn(!S_ISDIR(dir->i_mode) || !S_ISDIR(h_dir->i_mode));
+
+       dir->i_nlink += h_dir->i_nlink - 2;
+       if (h_dir->i_nlink < 2)
+               dir->i_nlink += 2;
+}
+
+void au_sub_nlink(struct inode *dir, struct inode *h_dir)
+{
+       AuDebugOn(!S_ISDIR(dir->i_mode) || !S_ISDIR(h_dir->i_mode));
+
+       dir->i_nlink -= h_dir->i_nlink - 2;
+       if (h_dir->i_nlink < 2)
+               dir->i_nlink -= 2;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int reopen_dir(struct file *file)
+{
+       int err;
+       unsigned int flags;
+       aufs_bindex_t bindex, btail, bstart;
+       struct dentry *dentry, *h_dentry;
+       struct file *h_file;
+
+       /* open all lower dirs */
+       dentry = file->f_dentry;
+       bstart = au_dbstart(dentry);
+       for (bindex = au_fbstart(file); bindex < bstart; bindex++)
+               au_set_h_fptr(file, bindex, NULL);
+       au_set_fbstart(file, bstart);
+
+       btail = au_dbtaildir(dentry);
+       for (bindex = au_fbend(file); btail < bindex; bindex--)
+               au_set_h_fptr(file, bindex, NULL);
+       au_set_fbend(file, btail);
+
+       flags = file->f_flags;
+       for (bindex = bstart; bindex <= btail; bindex++) {
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (!h_dentry)
+                       continue;
+               h_file = au_h_fptr(file, bindex);
+               if (h_file)
+                       continue;
+
+               h_file = au_h_open(dentry, bindex, flags, file);
+               err = PTR_ERR(h_file);
+               if (IS_ERR(h_file))
+                       goto out; /* close all? */
+               au_set_h_fptr(file, bindex, h_file);
+       }
+       au_update_figen(file);
+       /* todo: necessary? */
+       /* file->f_ra = h_file->f_ra; */
+       err = 0;
+
+ out:
+       return err;
+}
+
+static int do_open_dir(struct file *file, int flags)
+{
+       int err;
+       aufs_bindex_t bindex, btail;
+       struct dentry *dentry, *h_dentry;
+       struct file *h_file;
+
+       err = 0;
+       dentry = file->f_dentry;
+       au_set_fvdir_cache(file, NULL);
+       au_fi(file)->fi_maintain_plink = 0;
+       file->f_version = dentry->d_inode->i_version;
+       bindex = au_dbstart(dentry);
+       au_set_fbstart(file, bindex);
+       btail = au_dbtaildir(dentry);
+       au_set_fbend(file, btail);
+       for (; !err && bindex <= btail; bindex++) {
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (!h_dentry)
+                       continue;
+
+               h_file = au_h_open(dentry, bindex, flags, file);
+               if (IS_ERR(h_file)) {
+                       err = PTR_ERR(h_file);
+                       break;
+               }
+               au_set_h_fptr(file, bindex, h_file);
+       }
+       au_update_figen(file);
+       /* todo: necessary? */
+       /* file->f_ra = h_file->f_ra; */
+       if (!err)
+               return 0; /* success */
+
+       /* close all */
+       for (bindex = au_fbstart(file); bindex <= btail; bindex++)
+               au_set_h_fptr(file, bindex, NULL);
+       au_set_fbstart(file, -1);
+       au_set_fbend(file, -1);
+       return err;
+}
+
+static int aufs_open_dir(struct inode *inode __maybe_unused,
+                        struct file *file)
+{
+       return au_do_open(file, do_open_dir);
+}
+
+static int aufs_release_dir(struct inode *inode __maybe_unused,
+                           struct file *file)
+{
+       struct au_vdir *vdir_cache;
+       struct super_block *sb;
+       struct au_sbinfo *sbinfo;
+
+       sb = file->f_dentry->d_sb;
+       si_noflush_read_lock(sb);
+       fi_write_lock(file);
+       vdir_cache = au_fvdir_cache(file);
+       if (vdir_cache)
+               au_vdir_free(vdir_cache);
+       if (au_fi(file)->fi_maintain_plink) {
+               sbinfo = au_sbi(sb);
+               au_fclr_si(sbinfo, MAINTAIN_PLINK);
+               wake_up_all(&sbinfo->si_plink_wq);
+       }
+       fi_write_unlock(file);
+       au_finfo_fin(file);
+       si_read_unlock(sb);
+       return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_do_fsync_dir_no_file(struct dentry *dentry, int datasync)
+{
+       int err;
+       aufs_bindex_t bend, bindex;
+       struct inode *inode;
+       struct super_block *sb;
+
+       err = 0;
+       sb = dentry->d_sb;
+       inode = dentry->d_inode;
+       IMustLock(inode);
+       bend = au_dbend(dentry);
+       for (bindex = au_dbstart(dentry); !err && bindex <= bend; bindex++) {
+               struct path h_path;
+               struct inode *h_inode;
+
+               if (au_test_ro(sb, bindex, inode))
+                       continue;
+               h_path.dentry = au_h_dptr(dentry, bindex);
+               if (!h_path.dentry)
+                       continue;
+               h_inode = h_path.dentry->d_inode;
+               if (!h_inode)
+                       continue;
+
+               /* no mnt_want_write() */
+               /* cf. fs/nsfd/vfs.c and fs/nfsd/nfs4recover.c */
+               /* todo: inotiry fired? */
+               h_path.mnt = au_sbr_mnt(sb, bindex);
+               mutex_lock(&h_inode->i_mutex);
+               err = filemap_fdatawrite(h_inode->i_mapping);
+               AuDebugOn(!h_inode->i_fop);
+               if (!err && h_inode->i_fop->fsync)
+                       err = h_inode->i_fop->fsync(NULL, h_path.dentry,
+                                                   datasync);
+               if (!err)
+                       err = filemap_fdatawrite(h_inode->i_mapping);
+               if (!err)
+                       vfsub_update_h_iattr(&h_path, /*did*/NULL); /*ignore*/
+               mutex_unlock(&h_inode->i_mutex);
+       }
+
+       return err;
+}
+
+static int au_do_fsync_dir(struct file *file, int datasync)
+{
+       int err;
+       aufs_bindex_t bend, bindex;
+       struct file *h_file;
+       struct super_block *sb;
+       struct inode *inode;
+       struct mutex *h_mtx;
+
+       err = au_reval_and_lock_fdi(file, reopen_dir, /*wlock*/1);
+       if (unlikely(err))
+               goto out;
+
+       sb = file->f_dentry->d_sb;
+       inode = file->f_dentry->d_inode;
+       bend = au_fbend(file);
+       for (bindex = au_fbstart(file); !err && bindex <= bend; bindex++) {
+               h_file = au_h_fptr(file, bindex);
+               if (!h_file || au_test_ro(sb, bindex, inode))
+                       continue;
+
+               err = vfs_fsync(h_file, h_file->f_dentry, datasync);
+               if (!err) {
+                       h_mtx = &h_file->f_dentry->d_inode->i_mutex;
+                       mutex_lock(h_mtx);
+                       vfsub_update_h_iattr(&h_file->f_path, /*did*/NULL);
+                       /*ignore*/
+                       mutex_unlock(h_mtx);
+               }
+       }
+
+ out:
+       return err;
+}
+
+/*
+ * @file may be NULL
+ */
+static int aufs_fsync_dir(struct file *file, struct dentry *dentry,
+                         int datasync)
+{
+       int err;
+       struct super_block *sb;
+
+       IMustLock(dentry->d_inode);
+
+       err = 0;
+       sb = dentry->d_sb;
+       si_noflush_read_lock(sb);
+       if (file)
+               err = au_do_fsync_dir(file, datasync);
+       else {
+               di_write_lock_child(dentry);
+               err = au_do_fsync_dir_no_file(dentry, datasync);
+       }
+       au_cpup_attr_timesizes(dentry->d_inode);
+       di_write_unlock(dentry);
+       if (file)
+               fi_write_unlock(file);
+
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int aufs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+       int err;
+       struct dentry *dentry;
+       struct inode *inode;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       inode = dentry->d_inode;
+       IMustLock(inode);
+
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_reval_and_lock_fdi(file, reopen_dir, /*wlock*/1);
+       if (unlikely(err))
+               goto out;
+       err = au_vdir_init(file);
+       di_downgrade_lock(dentry, AuLock_IR);
+       if (unlikely(err))
+               goto out_unlock;
+
+       if (!au_test_nfsd(current)) {
+               err = au_vdir_fill_de(file, dirent, filldir);
+               fsstack_copy_attr_atime(inode,
+                                       au_h_iptr(inode, au_ibstart(inode)));
+       } else {
+               /*
+                * nfsd filldir may call lookup_one_len(), vfs_getattr(),
+                * encode_fh() and others.
+                */
+               struct inode *h_inode = au_h_iptr(inode, au_ibstart(inode));
+
+               di_read_unlock(dentry, AuLock_IR);
+               si_read_unlock(sb);
+               lockdep_off();
+               err = au_vdir_fill_de(file, dirent, filldir);
+               lockdep_on();
+               fsstack_copy_attr_atime(inode, h_inode);
+               fi_write_unlock(file);
+
+               AuTraceErr(err);
+               return err;
+       }
+
+ out_unlock:
+       di_read_unlock(dentry, AuLock_IR);
+       fi_write_unlock(file);
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+#define AuTestEmpty_WHONLY     1
+#define AuTestEmpty_CALLED     (1 << 2)
+#define au_ftest_testempty(flags, name)        ((flags) & AuTestEmpty_##name)
+#define au_fset_testempty(flags, name) { (flags) |= AuTestEmpty_##name; }
+#define au_fclr_testempty(flags, name) { (flags) &= ~AuTestEmpty_##name; }
+
+struct test_empty_arg {
+       struct au_nhash *whlist;
+       unsigned int flags;
+       int err;
+       aufs_bindex_t bindex;
+};
+
+static int test_empty_cb(void *__arg, const char *__name, int namelen,
+                        loff_t offset __maybe_unused, u64 ino __maybe_unused,
+                        unsigned int d_type __maybe_unused)
+{
+       struct test_empty_arg *arg = __arg;
+       char *name = (void *)__name;
+
+       arg->err = 0;
+       au_fset_testempty(arg->flags, CALLED);
+       /* smp_mb(); */
+       if (name[0] == '.'
+           && (namelen == 1 || (name[1] == '.' && namelen == 2)))
+               goto out; /* success */
+
+       if (namelen <= AUFS_WH_PFX_LEN
+           || memcmp(name, AUFS_WH_PFX, AUFS_WH_PFX_LEN)) {
+               if (au_ftest_testempty(arg->flags, WHONLY)
+                   && !au_nhash_test_known_wh(arg->whlist, name, namelen))
+                       arg->err = -ENOTEMPTY;
+               goto out;
+       }
+
+       name += AUFS_WH_PFX_LEN;
+       namelen -= AUFS_WH_PFX_LEN;
+       if (!au_nhash_test_known_wh(arg->whlist, name, namelen))
+               arg->err = au_nhash_append_wh
+                       (arg->whlist, name, namelen, arg->bindex);
+
+ out:
+       /* smp_mb(); */
+       AuTraceErr(arg->err);
+       return arg->err;
+}
+
+static int do_test_empty(struct dentry *dentry, struct test_empty_arg *arg)
+{
+       int err;
+       struct file *h_file;
+
+       h_file = au_h_open(dentry, arg->bindex,
+                          O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_LARGEFILE,
+                          /*file*/NULL);
+       err = PTR_ERR(h_file);
+       if (IS_ERR(h_file))
+               goto out;
+
+       err = 0;
+       if (!au_opt_test(au_mntflags(dentry->d_sb), UDBA_NONE)
+           && !h_file->f_dentry->d_inode->i_nlink)
+               goto out_put;
+
+       do {
+               arg->err = 0;
+               au_fclr_testempty(arg->flags, CALLED);
+               /* smp_mb(); */
+               err = vfsub_readdir(h_file, test_empty_cb, arg);
+               if (err >= 0)
+                       err = arg->err;
+       } while (!err && au_ftest_testempty(arg->flags, CALLED));
+
+ out_put:
+       fput(h_file);
+       au_sbr_put(dentry->d_sb, arg->bindex);
+ out:
+       return err;
+}
+
+struct do_test_empty_args {
+       int *errp;
+       struct dentry *dentry;
+       struct test_empty_arg *arg;
+};
+
+static void call_do_test_empty(void *args)
+{
+       struct do_test_empty_args *a = args;
+       *a->errp = do_test_empty(a->dentry, a->arg);
+}
+
+static int sio_test_empty(struct dentry *dentry, struct test_empty_arg *arg)
+{
+       int err, wkq_err;
+       struct dentry *h_dentry;
+       struct inode *h_inode;
+
+       h_dentry = au_h_dptr(dentry, arg->bindex);
+       h_inode = h_dentry->d_inode;
+       mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+       err = au_test_h_perm_sio(h_inode, MAY_EXEC | MAY_READ);
+       mutex_unlock(&h_inode->i_mutex);
+       if (!err)
+               err = do_test_empty(dentry, arg);
+       else {
+               struct do_test_empty_args args = {
+                       .errp   = &err,
+                       .dentry = dentry,
+                       .arg    = arg
+               };
+               unsigned int flags = arg->flags;
+
+               wkq_err = au_wkq_wait(call_do_test_empty, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+               arg->flags = flags;
+       }
+
+       return err;
+}
+
+int au_test_empty_lower(struct dentry *dentry)
+{
+       int err;
+       aufs_bindex_t bindex, bstart, btail;
+       struct test_empty_arg arg;
+       struct au_nhash *whlist;
+
+       whlist = au_nhash_alloc(dentry->d_sb, /*bend*/0, GFP_NOFS);
+       err = PTR_ERR(whlist);
+       if (IS_ERR(whlist))
+               goto out;
+
+       bstart = au_dbstart(dentry);
+       arg.whlist = whlist;
+       arg.flags = 0;
+       arg.bindex = bstart;
+       err = do_test_empty(dentry, &arg);
+       if (unlikely(err))
+               goto out_whlist;
+
+       au_fset_testempty(arg.flags, WHONLY);
+       btail = au_dbtaildir(dentry);
+       for (bindex = bstart + 1; !err && bindex <= btail; bindex++) {
+               struct dentry *h_dentry;
+
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (h_dentry && h_dentry->d_inode) {
+                       arg.bindex = bindex;
+                       err = do_test_empty(dentry, &arg);
+               }
+       }
+
+ out_whlist:
+       au_nhash_wh_free(whlist, /*bend*/0);
+ out:
+       return err;
+}
+
+int au_test_empty(struct dentry *dentry, struct au_nhash *whlist)
+{
+       int err;
+       struct test_empty_arg arg;
+       aufs_bindex_t bindex, btail;
+
+       err = 0;
+       arg.whlist = whlist;
+       arg.flags = AuTestEmpty_WHONLY;
+       btail = au_dbtaildir(dentry);
+       for (bindex = au_dbstart(dentry); !err && bindex <= btail; bindex++) {
+               struct dentry *h_dentry;
+
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (h_dentry && h_dentry->d_inode) {
+                       arg.bindex = bindex;
+                       err = sio_test_empty(dentry, &arg);
+               }
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+const struct file_operations aufs_dir_fop = {
+       .read           = generic_read_dir,
+       .readdir        = aufs_readdir,
+       .unlocked_ioctl = aufs_ioctl_dir,
+       .open           = aufs_open_dir,
+       .release        = aufs_release_dir,
+       .flush          = aufs_flush,
+       .fsync          = aufs_fsync_dir
+};
diff --git a/fs/aufs/dir.h b/fs/aufs/dir.h
new file mode 100644
index 0000000..f41f050
--- /dev/null
+++ b/fs/aufs/dir.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * directory operations
+ */
+
+#ifndef __AUFS_DIR_H__
+#define __AUFS_DIR_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/aufs_type.h>
+
+/* ---------------------------------------------------------------------- */
+
+/* need to be faster and smaller */
+
+struct au_nhash {
+       unsigned int nh_num;
+       struct hlist_head *nh_head;
+};
+
+struct au_vdir_destr {
+       unsigned char   len;
+       unsigned char   name[0];
+} __packed;
+
+struct au_vdir_dehstr {
+       struct hlist_node       hash;
+       struct au_vdir_destr    *str;
+};
+
+struct au_vdir_de {
+       ino_t                   de_ino;
+       unsigned char           de_type;
+       /* caution: packed */
+       struct au_vdir_destr    de_str;
+} __packed;
+
+struct au_vdir_wh {
+       struct hlist_node       wh_hash;
+       aufs_bindex_t           wh_bindex;
+       struct au_vdir_destr    wh_str;
+} __packed;
+
+union au_vdir_deblk_p {
+       unsigned char           *deblk;
+       struct au_vdir_de       *de;
+};
+
+struct au_vdir {
+       unsigned char   **vd_deblk;
+       unsigned long   vd_nblk;
+       unsigned int    vd_deblk_sz;
+       struct {
+               unsigned long           ul;
+               union au_vdir_deblk_p   p;
+       } vd_last;
+
+       unsigned long   vd_version;
+       unsigned long   vd_jiffy;
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* dir.c */
+extern const struct file_operations aufs_dir_fop;
+void au_add_nlink(struct inode *dir, struct inode *h_dir);
+void au_sub_nlink(struct inode *dir, struct inode *h_dir);
+int au_test_empty_lower(struct dentry *dentry);
+int au_test_empty(struct dentry *dentry, struct au_nhash *whlist);
+
+/* vdir.c */
+struct au_nhash *au_nhash_alloc(struct super_block *sb, aufs_bindex_t bend,
+                               gfp_t gfp);
+void au_nhash_wh_free(struct au_nhash *whlist, aufs_bindex_t bend);
+int au_nhash_test_longer_wh(struct au_nhash *whlist, aufs_bindex_t btgt,
+                           int limit);
+int au_nhash_test_known_wh(struct au_nhash *whlist, char *name, int namelen);
+int au_nhash_append_wh(struct au_nhash *whlist, char *name, int namelen,
+                      aufs_bindex_t bindex);
+void au_vdir_free(struct au_vdir *vdir);
+int au_vdir_init(struct file *file);
+int au_vdir_fill_de(struct file *file, void *dirent, filldir_t filldir);
+
+/* ioctl.c */
+long aufs_ioctl_dir(struct file *file, unsigned int cmd, unsigned long arg);
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_DIR_H__ */
diff --git a/fs/aufs/export.c b/fs/aufs/export.c
new file mode 100644
index 0000000..7dd7f33
--- /dev/null
+++ b/fs/aufs/export.c
@@ -0,0 +1,725 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * export via nfs
+ */
+
+#include <linux/exportfs.h>
+#include <linux/mnt_namespace.h>
+#include <linux/random.h>
+#include "aufs.h"
+
+union conv {
+#ifdef CONFIG_AUFS_INO_T_64
+       __u32 a[2];
+#else
+       __u32 a[1];
+#endif
+       ino_t ino;
+};
+
+static ino_t decode_ino(__u32 *a)
+{
+       union conv u;
+
+       BUILD_BUG_ON(sizeof(u.ino) != sizeof(u.a));
+       u.a[0] = a[0];
+#ifdef CONFIG_AUFS_INO_T_64
+       u.a[1] = a[1];
+#endif
+       return u.ino;
+}
+
+static void encode_ino(__u32 *a, ino_t ino)
+{
+       union conv u;
+
+       u.ino = ino;
+       a[0] = u.a[0];
+#ifdef CONFIG_AUFS_INO_T_64
+       a[1] = u.a[1];
+#endif
+}
+
+/* NFS file handle */
+enum {
+       Fh_br_id,
+       Fh_sigen,
+#ifdef CONFIG_AUFS_INO_T_64
+       /* support 64bit inode number */
+       Fh_ino1,
+       Fh_ino2,
+       Fh_dir_ino1,
+       Fh_dir_ino2,
+#else
+       Fh_ino1,
+       Fh_dir_ino1,
+#endif
+       Fh_igen,
+       Fh_h_type,
+       Fh_tail,
+
+       Fh_ino = Fh_ino1,
+       Fh_dir_ino = Fh_dir_ino1
+};
+
+static int au_test_anon(struct dentry *dentry)
+{
+       return !!(dentry->d_flags & DCACHE_DISCONNECTED);
+}
+
+/* ---------------------------------------------------------------------- */
+/* inode generation external table */
+
+int au_xigen_inc(struct inode *inode)
+{
+       int err;
+       loff_t pos;
+       ssize_t sz;
+       __u32 igen;
+       struct super_block *sb;
+       struct au_sbinfo *sbinfo;
+
+       err = 0;
+       sb = inode->i_sb;
+       if (unlikely(!au_opt_test(au_mntflags(sb), XINO)))
+               goto out;
+
+       pos = inode->i_ino;
+       pos *= sizeof(igen);
+       igen = inode->i_generation + 1;
+       sbinfo = au_sbi(sb);
+       sz = xino_fwrite(sbinfo->si_xwrite, sbinfo->si_xigen, &igen,
+                        sizeof(igen), &pos);
+       if (sz == sizeof(igen))
+               goto out; /* success */
+
+       err = sz;
+       if (unlikely(sz >= 0)) {
+               err = -EIO;
+               AuIOErr("xigen error (%zd)\n", sz);
+       }
+
+ out:
+       return err;
+}
+
+int au_xigen_new(struct inode *inode)
+{
+       int err;
+       loff_t pos;
+       ssize_t sz;
+       struct super_block *sb;
+       struct au_sbinfo *sbinfo;
+       struct file *file;
+
+       err = 0;
+       /* todo: dirty, at mount time */
+       if (inode->i_ino == AUFS_ROOT_INO)
+               goto out;
+       sb = inode->i_sb;
+       if (unlikely(!au_opt_test(au_mntflags(sb), XINO)))
+               goto out;
+
+       err = -EFBIG;
+       pos = inode->i_ino;
+       if (unlikely(au_loff_max / sizeof(inode->i_generation) - 1 < pos)) {
+               AuIOErr1("too large i%lld\n", pos);
+               goto out;
+       }
+       pos *= sizeof(inode->i_generation);
+
+       err = 0;
+       sbinfo = au_sbi(sb);
+       file = sbinfo->si_xigen;
+       BUG_ON(!file);
+
+       if (i_size_read(file->f_dentry->d_inode)
+           < pos + sizeof(inode->i_generation)) {
+               inode->i_generation = atomic_inc_return(&sbinfo->si_xigen_next);
+               sz = xino_fwrite(sbinfo->si_xwrite, file, &inode->i_generation,
+                                sizeof(inode->i_generation), &pos);
+       } else
+               sz = xino_fread(sbinfo->si_xread, file, &inode->i_generation,
+                               sizeof(inode->i_generation), &pos);
+       if (sz == sizeof(inode->i_generation))
+               goto out; /* success */
+
+       err = sz;
+       if (unlikely(sz >= 0)) {
+               err = -EIO;
+               AuIOErr("xigen error (%zd)\n", sz);
+       }
+
+ out:
+       return err;
+}
+
+int au_xigen_set(struct super_block *sb, struct file *base)
+{
+       int err;
+       struct au_sbinfo *sbinfo;
+       struct file *file;
+
+       sbinfo = au_sbi(sb);
+       file = au_xino_create2(base, sbinfo->si_xigen);
+       err = PTR_ERR(file);
+       if (IS_ERR(file))
+               goto out;
+       err = 0;
+       if (sbinfo->si_xigen)
+               fput(sbinfo->si_xigen);
+       sbinfo->si_xigen = file;
+
+ out:
+       return err;
+}
+
+void au_xigen_clr(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+
+       sbinfo = au_sbi(sb);
+       if (sbinfo->si_xigen) {
+               fput(sbinfo->si_xigen);
+               sbinfo->si_xigen = NULL;
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct dentry *decode_by_ino(struct super_block *sb, ino_t ino,
+                                   ino_t dir_ino)
+{
+       struct dentry *dentry, *d;
+       struct inode *inode;
+       unsigned int sigen;
+
+       dentry = NULL;
+       inode = ilookup(sb, ino);
+       if (!inode)
+               goto out;
+
+       dentry = ERR_PTR(-ESTALE);
+       sigen = au_sigen(sb);
+       if (unlikely(is_bad_inode(inode)
+                    || IS_DEADDIR(inode)
+                    || sigen != au_iigen(inode)))
+               goto out_iput;
+
+       dentry = NULL;
+       if (!dir_ino || S_ISDIR(inode->i_mode))
+               dentry = d_find_alias(inode);
+       else {
+               spin_lock(&dcache_lock);
+               list_for_each_entry(d, &inode->i_dentry, d_alias)
+                       if (!au_test_anon(d)
+                           && d->d_parent->d_inode->i_ino == dir_ino) {
+                               dentry = dget_locked(d);
+                               break;
+                       }
+               spin_unlock(&dcache_lock);
+       }
+       if (unlikely(dentry && sigen != au_digen(dentry))) {
+               dput(dentry);
+               dentry = ERR_PTR(-ESTALE);
+       }
+
+ out_iput:
+       iput(inode);
+ out:
+       return dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* todo: dirty? */
+/* if exportfs_decode_fh() passed vfsmount*, we could be happy */
+static struct vfsmount *au_mnt_get(struct super_block *sb)
+{
+       struct mnt_namespace *ns;
+       struct vfsmount *pos, *mnt;
+
+       spin_lock(&vfsmount_lock);
+       /* no get/put ?? */
+       AuDebugOn(!current->nsproxy);
+       ns = current->nsproxy->mnt_ns;
+       AuDebugOn(!ns);
+       mnt = NULL;
+       /* the order (reverse) will not be a problem */
+       list_for_each_entry(pos, &ns->list, mnt_list)
+               if (pos->mnt_sb == sb) {
+                       mnt = mntget(pos);
+                       break;
+               }
+       spin_unlock(&vfsmount_lock);
+       AuDebugOn(!mnt);
+
+       return mnt;
+}
+
+struct au_nfsd_si_lock {
+       const unsigned int sigen;
+       const aufs_bindex_t br_id;
+       unsigned char force_lock;
+};
+
+static aufs_bindex_t si_nfsd_read_lock(struct super_block *sb,
+                                      struct au_nfsd_si_lock *nsi_lock)
+{
+       aufs_bindex_t bindex;
+
+       si_read_lock(sb, AuLock_FLUSH);
+
+       /* branch id may be wrapped around */
+       bindex = au_br_index(sb, nsi_lock->br_id);
+       if (bindex >= 0 && nsi_lock->sigen + AUFS_BRANCH_MAX > au_sigen(sb))
+               goto out; /* success */
+
+       if (!nsi_lock->force_lock)
+               si_read_unlock(sb);
+       bindex = -1;
+
+ out:
+       return bindex;
+}
+
+struct find_name_by_ino {
+       int called, found;
+       ino_t ino;
+       char *name;
+       int namelen;
+};
+
+static int
+find_name_by_ino(void *arg, const char *name, int namelen, loff_t offset,
+                u64 ino, unsigned int d_type)
+{
+       struct find_name_by_ino *a = arg;
+
+       a->called++;
+       if (a->ino != ino)
+               return 0;
+
+       memcpy(a->name, name, namelen);
+       a->namelen = namelen;
+       a->found = 1;
+       return 1;
+}
+
+static struct dentry *au_lkup_by_ino(struct path *path, ino_t ino,
+                                    struct au_nfsd_si_lock *nsi_lock)
+{
+       struct dentry *dentry, *parent;
+       struct file *file;
+       struct inode *dir;
+       struct find_name_by_ino arg;
+       int err;
+
+       parent = path->dentry;
+       if (nsi_lock)
+               si_read_unlock(parent->d_sb);
+       path_get(path);
+       file = dentry_open(parent, path->mnt, au_dir_roflags, current_cred());
+       dentry = (void *)file;
+       if (IS_ERR(file))
+               goto out;
+
+       dentry = ERR_PTR(-ENOMEM);
+       arg.name = __getname();
+       if (unlikely(!arg.name))
+               goto out_file;
+       arg.ino = ino;
+       arg.found = 0;
+       do {
+               arg.called = 0;
+               /* smp_mb(); */
+               err = vfsub_readdir(file, find_name_by_ino, &arg);
+       } while (!err && !arg.found && arg.called);
+       dentry = ERR_PTR(err);
+       if (unlikely(err))
+               goto out_name;
+       dentry = ERR_PTR(-ENOENT);
+       if (!arg.found)
+               goto out_name;
+
+       /* do not call au_lkup_one() */
+       dir = parent->d_inode;
+       mutex_lock(&dir->i_mutex);
+       dentry = vfsub_lookup_one_len(arg.name, parent, arg.namelen);
+       mutex_unlock(&dir->i_mutex);
+       AuTraceErrPtr(dentry);
+       if (IS_ERR(dentry))
+               goto out_name;
+       AuDebugOn(au_test_anon(dentry));
+       if (unlikely(!dentry->d_inode)) {
+               dput(dentry);
+               dentry = ERR_PTR(-ENOENT);
+       }
+
+ out_name:
+       __putname(arg.name);
+ out_file:
+       fput(file);
+ out:
+       if (unlikely(nsi_lock
+                    && si_nfsd_read_lock(parent->d_sb, nsi_lock) < 0))
+               if (!IS_ERR(dentry)) {
+                       dput(dentry);
+                       dentry = ERR_PTR(-ESTALE);
+               }
+       AuTraceErrPtr(dentry);
+       return dentry;
+}
+
+static struct dentry *decode_by_dir_ino(struct super_block *sb, ino_t ino,
+                                       ino_t dir_ino,
+                                       struct au_nfsd_si_lock *nsi_lock)
+{
+       struct dentry *dentry;
+       struct path path;
+
+       if (dir_ino != AUFS_ROOT_INO) {
+               path.dentry = decode_by_ino(sb, dir_ino, 0);
+               dentry = path.dentry;
+               if (!path.dentry || IS_ERR(path.dentry))
+                       goto out;
+               AuDebugOn(au_test_anon(path.dentry));
+       } else
+               path.dentry = dget(sb->s_root);
+
+       path.mnt = au_mnt_get(sb);
+       dentry = au_lkup_by_ino(&path, ino, nsi_lock);
+       path_put(&path);
+
+ out:
+       AuTraceErrPtr(dentry);
+       return dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int h_acceptable(void *expv, struct dentry *dentry)
+{
+       return 1;
+}
+
+static char *au_build_path(struct dentry *h_parent, struct path *h_rootpath,
+                          char *buf, int len, struct super_block *sb)
+{
+       char *p;
+       int n;
+       struct path path;
+
+       p = d_path(h_rootpath, buf, len);
+       if (IS_ERR(p))
+               goto out;
+       n = strlen(p);
+
+       path.mnt = h_rootpath->mnt;
+       path.dentry = h_parent;
+       p = d_path(&path, buf, len);
+       if (IS_ERR(p))
+               goto out;
+       if (n != 1)
+               p += n;
+
+       path.mnt = au_mnt_get(sb);
+       path.dentry = sb->s_root;
+       p = d_path(&path, buf, len - strlen(p));
+       mntput(path.mnt);
+       if (IS_ERR(p))
+               goto out;
+       if (n != 1)
+               p[strlen(p)] = '/';
+
+ out:
+       AuTraceErrPtr(p);
+       return p;
+}
+
+static
+struct dentry *decode_by_path(struct super_block *sb, aufs_bindex_t bindex,
+                             ino_t ino, __u32 *fh, int fh_len,
+                             struct au_nfsd_si_lock *nsi_lock)
+{
+       struct dentry *dentry, *h_parent, *root;
+       struct super_block *h_sb;
+       char *pathname, *p;
+       struct vfsmount *h_mnt;
+       struct au_branch *br;
+       int err;
+       struct path path;
+
+       br = au_sbr(sb, bindex);
+       /* au_br_get(br); */
+       h_mnt = br->br_mnt;
+       h_sb = h_mnt->mnt_sb;
+       /* todo: call lower fh_to_dentry()? fh_to_parent()? */
+       h_parent = exportfs_decode_fh(h_mnt, (void *)(fh + Fh_tail),
+                                     fh_len - Fh_tail, fh[Fh_h_type],
+                                     h_acceptable, /*context*/NULL);
+       dentry = h_parent;
+       if (unlikely(!h_parent || IS_ERR(h_parent))) {
+               AuWarn1("%s decode_fh failed, %ld\n",
+                       au_sbtype(h_sb), PTR_ERR(h_parent));
+               goto out;
+       }
+       dentry = NULL;
+       if (unlikely(au_test_anon(h_parent))) {
+               AuWarn1("%s decode_fh returned a disconnected dentry\n",
+                       au_sbtype(h_sb));
+               goto out_h_parent;
+       }
+
+       dentry = ERR_PTR(-ENOMEM);
+       pathname = (void *)__get_free_page(GFP_NOFS);
+       if (unlikely(!pathname))
+               goto out_h_parent;
+
+       root = sb->s_root;
+       path.mnt = h_mnt;
+       di_read_lock_parent(root, !AuLock_IR);
+       path.dentry = au_h_dptr(root, bindex);
+       di_read_unlock(root, !AuLock_IR);
+       p = au_build_path(h_parent, &path, pathname, PAGE_SIZE, sb);
+       dentry = (void *)p;
+       if (IS_ERR(p))
+               goto out_pathname;
+
+       si_read_unlock(sb);
+       err = vfsub_kern_path(p, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
+       dentry = ERR_PTR(err);
+       if (unlikely(err))
+               goto out_relock;
+
+       dentry = ERR_PTR(-ENOENT);
+       AuDebugOn(au_test_anon(path.dentry));
+       if (unlikely(!path.dentry->d_inode))
+               goto out_path;
+
+       if (ino != path.dentry->d_inode->i_ino)
+               dentry = au_lkup_by_ino(&path, ino, /*nsi_lock*/NULL);
+       else
+               dentry = dget(path.dentry);
+
+ out_path:
+       path_put(&path);
+ out_relock:
+       if (unlikely(si_nfsd_read_lock(sb, nsi_lock) < 0))
+               if (!IS_ERR(dentry)) {
+                       dput(dentry);
+                       dentry = ERR_PTR(-ESTALE);
+               }
+ out_pathname:
+       free_page((unsigned long)pathname);
+ out_h_parent:
+       dput(h_parent);
+ out:
+       /* au_br_put(br); */
+       AuTraceErrPtr(dentry);
+       return dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct dentry *
+aufs_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len,
+                 int fh_type)
+{
+       struct dentry *dentry;
+       __u32 *fh = fid->raw;
+       ino_t ino, dir_ino;
+       aufs_bindex_t bindex;
+       struct au_nfsd_si_lock nsi_lock = {
+               .sigen          = fh[Fh_sigen],
+               .br_id          = fh[Fh_br_id],
+               .force_lock     = 0
+       };
+
+       AuDebugOn(fh_len < Fh_tail);
+
+       dentry = ERR_PTR(-ESTALE);
+       /* branch id may be wrapped around */
+       bindex = si_nfsd_read_lock(sb, &nsi_lock);
+       if (unlikely(bindex < 0))
+               goto out;
+       nsi_lock.force_lock = 1;
+
+       /* is this inode still cached? */
+       ino = decode_ino(fh + Fh_ino);
+       AuDebugOn(ino == AUFS_ROOT_INO);
+       dir_ino = decode_ino(fh + Fh_dir_ino);
+       dentry = decode_by_ino(sb, ino, dir_ino);
+       if (IS_ERR(dentry))
+               goto out_unlock;
+       if (dentry)
+               goto accept;
+
+       /* is the parent dir cached? */
+       dentry = decode_by_dir_ino(sb, ino, dir_ino, &nsi_lock);
+       if (IS_ERR(dentry))
+               goto out_unlock;
+       if (dentry)
+               goto accept;
+
+       /* lookup path */
+       dentry = decode_by_path(sb, bindex, ino, fh, fh_len, &nsi_lock);
+       if (IS_ERR(dentry))
+               goto out_unlock;
+       if (unlikely(!dentry))
+               /* todo?: make it ESTALE */
+               goto out_unlock;
+
+ accept:
+       if (dentry->d_inode->i_generation == fh[Fh_igen])
+               goto out_unlock; /* success */
+
+       dput(dentry);
+       dentry = ERR_PTR(-ESTALE);
+ out_unlock:
+       si_read_unlock(sb);
+ out:
+       AuTraceErrPtr(dentry);
+       return dentry;
+}
+
+#if 0 /* reserved for future use */
+/* support subtreecheck option */
+static struct dentry *aufs_fh_to_parent(struct super_block *sb, struct fid *fid,
+                                       int fh_len, int fh_type)
+{
+       struct dentry *parent;
+       __u32 *fh = fid->raw;
+       ino_t dir_ino;
+
+       dir_ino = decode_ino(fh + Fh_dir_ino);
+       parent = decode_by_ino(sb, dir_ino, 0);
+       if (IS_ERR(parent))
+               goto out;
+       if (!parent)
+               parent = decode_by_path(sb, au_br_index(sb, fh[Fh_br_id]),
+                                       dir_ino, fh, fh_len);
+
+ out:
+       AuTraceErrPtr(parent);
+       return parent;
+}
+#endif
+
+/* ---------------------------------------------------------------------- */
+
+static int aufs_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
+                         int connectable)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       struct super_block *sb, *h_sb;
+       struct inode *inode;
+       struct dentry *parent, *h_parent;
+       struct au_branch *br;
+
+       AuDebugOn(au_test_anon(dentry));
+
+       parent = NULL;
+       err = -ENOSPC;
+       if (unlikely(*max_len <= Fh_tail)) {
+               AuWarn1("NFSv2 client (max_len %d)?\n", *max_len);
+               goto out;
+       }
+
+       err = FILEID_ROOT;
+       if (IS_ROOT(dentry)) {
+               AuDebugOn(dentry->d_inode->i_ino != AUFS_ROOT_INO);
+               goto out;
+       }
+
+       err = -EIO;
+       h_parent = NULL;
+       sb = dentry->d_sb;
+       aufs_read_lock(dentry, AuLock_FLUSH | AuLock_IR);
+       parent = dget_parent(dentry);
+       di_read_lock_parent(parent, !AuLock_IR);
+       inode = dentry->d_inode;
+       AuDebugOn(!inode);
+#ifdef CONFIG_AUFS_DEBUG
+       if (unlikely(!au_opt_test(au_mntflags(sb), XINO)))
+               AuWarn1("NFS-exporting requires xino\n");
+#endif
+
+       bend = au_dbtaildir(parent);
+       for (bindex = au_dbstart(parent); bindex <= bend; bindex++) {
+               h_parent = au_h_dptr(parent, bindex);
+               if (h_parent) {
+                       dget(h_parent);
+                       break;
+               }
+       }
+       if (unlikely(!h_parent))
+               goto out_unlock;
+
+       err = -EPERM;
+       br = au_sbr(sb, bindex);
+       h_sb = br->br_mnt->mnt_sb;
+       if (unlikely(!h_sb->s_export_op)) {
+               AuErr1("%s branch is not exportable\n", au_sbtype(h_sb));
+               goto out_dput;
+       }
+
+       fh[Fh_br_id] = br->br_id;
+       fh[Fh_sigen] = au_sigen(sb);
+       encode_ino(fh + Fh_ino, inode->i_ino);
+       encode_ino(fh + Fh_dir_ino, parent->d_inode->i_ino);
+       fh[Fh_igen] = inode->i_generation;
+
+       *max_len -= Fh_tail;
+       fh[Fh_h_type] = exportfs_encode_fh(h_parent, (void *)(fh + Fh_tail),
+                                          max_len,
+                                          /*connectable or subtreecheck*/0);
+       err = fh[Fh_h_type];
+       *max_len += Fh_tail;
+       /* todo: macros? */
+       if (err != 255)
+               err = 99;
+       else
+               AuWarn1("%s encode_fh failed\n", au_sbtype(h_sb));
+
+ out_dput:
+       dput(h_parent);
+ out_unlock:
+       di_read_unlock(parent, !AuLock_IR);
+       dput(parent);
+       aufs_read_unlock(dentry, AuLock_IR);
+ out:
+       if (unlikely(err < 0))
+               err = 255;
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct export_operations aufs_export_op = {
+       .fh_to_dentry   = aufs_fh_to_dentry,
+       /* .fh_to_parent        = aufs_fh_to_parent, */
+       .encode_fh      = aufs_encode_fh
+};
+
+void au_export_init(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+       __u32 u;
+
+       sb->s_export_op = &aufs_export_op;
+       sbinfo = au_sbi(sb);
+       sbinfo->si_xigen = NULL;
+       get_random_bytes(&u, sizeof(u));
+       BUILD_BUG_ON(sizeof(u) != sizeof(int));
+       atomic_set(&sbinfo->si_xigen_next, u);
+}
diff --git a/fs/aufs/f_op.c b/fs/aufs/f_op.c
new file mode 100644
index 0000000..7841d99
--- /dev/null
+++ b/fs/aufs/f_op.c
@@ -0,0 +1,556 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * file and vm operations
+ */
+
+#include <linux/fs_stack.h>
+#include <linux/poll.h>
+#include "aufs.h"
+
+/* common function to regular file and dir */
+int aufs_flush(struct file *file, fl_owner_t id)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       struct dentry *dentry;
+       struct file *h_file;
+
+       dentry = file->f_dentry;
+       si_noflush_read_lock(dentry->d_sb);
+       fi_read_lock(file);
+       di_read_lock_child(dentry, AuLock_IW);
+
+       err = 0;
+       bend = au_fbend(file);
+       for (bindex = au_fbstart(file); !err && bindex <= bend; bindex++) {
+               h_file = au_h_fptr(file, bindex);
+               if (!h_file || !h_file->f_op || !h_file->f_op->flush)
+                       continue;
+
+               err = h_file->f_op->flush(h_file, id);
+               if (!err)
+                       vfsub_update_h_iattr(&h_file->f_path, /*did*/NULL);
+               /*ignore*/
+       }
+       au_cpup_attr_timesizes(dentry->d_inode);
+
+       di_read_unlock(dentry, AuLock_IW);
+       fi_read_unlock(file);
+       si_read_unlock(dentry->d_sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int do_open_nondir(struct file *file, int flags)
+{
+       int err;
+       aufs_bindex_t bindex;
+       struct file *h_file;
+       struct dentry *dentry;
+
+       err = 0;
+       dentry = file->f_dentry;
+       au_fi(file)->fi_h_vm_ops = NULL;
+       bindex = au_dbstart(dentry);
+       /* O_TRUNC is processed already */
+       BUG_ON(au_test_ro(dentry->d_sb, bindex, dentry->d_inode)
+              && (flags & O_TRUNC));
+
+       h_file = au_h_open(dentry, bindex, flags, file);
+       if (IS_ERR(h_file))
+               err = PTR_ERR(h_file);
+       else {
+               au_set_fbstart(file, bindex);
+               au_set_fbend(file, bindex);
+               au_set_h_fptr(file, bindex, h_file);
+               au_update_figen(file);
+               /* todo: necessary? */
+               /* file->f_ra = h_file->f_ra; */
+       }
+       return err;
+}
+
+static int aufs_open_nondir(struct inode *inode __maybe_unused,
+                           struct file *file)
+{
+       return au_do_open(file, do_open_nondir);
+}
+
+static int aufs_release_nondir(struct inode *inode __maybe_unused,
+                              struct file *file)
+{
+       struct super_block *sb = file->f_dentry->d_sb;
+
+       si_noflush_read_lock(sb);
+       au_finfo_fin(file);
+       si_read_unlock(sb);
+       return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static ssize_t aufs_read(struct file *file, char __user *buf, size_t count,
+                        loff_t *ppos)
+{
+       ssize_t err;
+       struct dentry *dentry;
+       struct file *h_file;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/0);
+       if (unlikely(err))
+               goto out;
+
+       h_file = au_h_fptr(file, au_fbstart(file));
+       err = vfsub_read_u(h_file, buf, count, ppos);
+       /* todo: necessary? */
+       /* file->f_ra = h_file->f_ra; */
+       fsstack_copy_attr_atime(dentry->d_inode, h_file->f_dentry->d_inode);
+
+       di_read_unlock(dentry, AuLock_IR);
+       fi_read_unlock(file);
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+static ssize_t aufs_write(struct file *file, const char __user *ubuf,
+                         size_t count, loff_t *ppos)
+{
+       ssize_t err;
+       aufs_bindex_t bstart;
+       struct au_pin pin;
+       struct dentry *dentry;
+       struct inode *inode;
+       struct super_block *sb;
+       struct file *h_file;
+       char __user *buf = (char __user *)ubuf;
+
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       inode = dentry->d_inode;
+       mutex_lock(&inode->i_mutex);
+       si_read_lock(sb, AuLock_FLUSH);
+
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/1);
+       if (unlikely(err))
+               goto out;
+
+       err = au_ready_to_write(file, -1, &pin);
+       di_downgrade_lock(dentry, AuLock_IR);
+       if (unlikely(err))
+               goto out_unlock;
+
+       bstart = au_fbstart(file);
+       h_file = au_h_fptr(file, bstart);
+       au_unpin(&pin);
+       err = vfsub_write_u(h_file, buf, count, ppos);
+       au_cpup_attr_timesizes(inode);
+       inode->i_mode = h_file->f_dentry->d_inode->i_mode;
+
+ out_unlock:
+       di_read_unlock(dentry, AuLock_IR);
+       fi_write_unlock(file);
+ out:
+       si_read_unlock(sb);
+       mutex_unlock(&inode->i_mutex);
+       return err;
+}
+
+static ssize_t aufs_splice_read(struct file *file, loff_t *ppos,
+                               struct pipe_inode_info *pipe, size_t len,
+                               unsigned int flags)
+{
+       ssize_t err;
+       struct file *h_file;
+       struct dentry *dentry;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/0);
+       if (unlikely(err))
+               goto out;
+
+       err = -EINVAL;
+       h_file = au_h_fptr(file, au_fbstart(file));
+       if (au_test_loopback_kthread()) {
+               file->f_mapping = h_file->f_mapping;
+               smp_mb(); /* unnecessary? */
+       }
+       err = vfsub_splice_to(h_file, ppos, pipe, len, flags);
+       /* todo: necessasry? */
+       /* file->f_ra = h_file->f_ra; */
+       fsstack_copy_attr_atime(dentry->d_inode, h_file->f_dentry->d_inode);
+
+       di_read_unlock(dentry, AuLock_IR);
+       fi_read_unlock(file);
+
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+static ssize_t
+aufs_splice_write(struct pipe_inode_info *pipe, struct file *file, loff_t *ppos,
+                 size_t len, unsigned int flags)
+{
+       ssize_t err;
+       struct au_pin pin;
+       struct dentry *dentry;
+       struct inode *inode;
+       struct super_block *sb;
+       struct file *h_file;
+
+       dentry = file->f_dentry;
+       inode = dentry->d_inode;
+       mutex_lock(&inode->i_mutex);
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/1);
+       if (unlikely(err))
+               goto out;
+
+       err = au_ready_to_write(file, -1, &pin);
+       di_downgrade_lock(dentry, AuLock_IR);
+       if (unlikely(err))
+               goto out_unlock;
+
+       h_file = au_h_fptr(file, au_fbstart(file));
+       au_unpin(&pin);
+       err = vfsub_splice_from(pipe, h_file, ppos, len, flags);
+       au_cpup_attr_timesizes(inode);
+       inode->i_mode = h_file->f_dentry->d_inode->i_mode;
+
+ out_unlock:
+       di_read_unlock(dentry, AuLock_IR);
+       fi_write_unlock(file);
+ out:
+       si_read_unlock(sb);
+       mutex_unlock(&inode->i_mutex);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct file *au_safe_file(struct vm_area_struct *vma)
+{
+       struct file *file;
+
+       file = vma->vm_file;
+       if (file->private_data && au_test_aufs(file->f_dentry->d_sb))
+               return file;
+       return NULL;
+}
+
+static void au_reset_file(struct vm_area_struct *vma, struct file *file)
+{
+       vma->vm_file = file;
+       /* smp_mb(); */ /* flush vm_file */
+}
+
+static int aufs_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       int err;
+       static DECLARE_WAIT_QUEUE_HEAD(wq);
+       struct file *file, *h_file;
+       struct au_finfo *finfo;
+
+       /* todo: non-robr mode, user vm_file as it is? */
+       wait_event(wq, (file = au_safe_file(vma)));
+
+       /* do not revalidate, no si lock */
+       finfo = au_fi(file);
+       h_file = finfo->fi_hfile[0 + finfo->fi_bstart].hf_file;
+       AuDebugOn(!h_file || !au_test_mmapped(file));
+
+       fi_write_lock(file);
+       vma->vm_file = h_file;
+       err = finfo->fi_h_vm_ops->fault(vma, vmf);
+       /* todo: necessary? */
+       /* file->f_ra = h_file->f_ra; */
+       au_reset_file(vma, file);
+       fi_write_unlock(file);
+#if 0 /* def CONFIG_SMP */
+       /* wake_up_nr(&wq, online_cpu - 1); */
+       wake_up_all(&wq);
+#else
+       wake_up(&wq);
+#endif
+
+       return err;
+}
+
+static struct vm_operations_struct aufs_vm_ops = {
+       .fault          = aufs_fault
+};
+
+/* ---------------------------------------------------------------------- */
+
+static struct vm_operations_struct *au_vm_ops(struct file *h_file,
+                                             struct vm_area_struct *vma)
+{
+       struct vm_operations_struct *vm_ops;
+       int err;
+
+       vm_ops = ERR_PTR(-ENODEV);
+       if (!h_file->f_op || !h_file->f_op->mmap)
+               goto out;
+
+       err = h_file->f_op->mmap(h_file, vma);
+       vm_ops = ERR_PTR(err);
+       if (unlikely(err))
+               goto out;
+
+       vm_ops = vma->vm_ops;
+       err = do_munmap(current->mm, vma->vm_start,
+                       vma->vm_end - vma->vm_start);
+       if (unlikely(err)) {
+               AuIOErr("failed internal unmapping %.*s, %d\n",
+                       AuDLNPair(h_file->f_dentry), err);
+               vm_ops = ERR_PTR(-EIO);
+       }
+
+ out:
+       return vm_ops;
+}
+
+static int aufs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+       int err;
+       unsigned char wlock, mmapped;
+       struct dentry *dentry;
+       struct super_block *sb;
+       struct file *h_file;
+       struct vm_operations_struct *vm_ops;
+
+       dentry = file->f_dentry;
+       mmapped = !!au_test_mmapped(file); /* can be harmless race condition */
+       wlock = !!(file->f_mode & FMODE_WRITE) && (vma->vm_flags & VM_SHARED);
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, wlock | !mmapped);
+       if (unlikely(err))
+               goto out;
+
+       if (wlock) {
+               struct au_pin pin;
+
+               err = au_ready_to_write(file, -1, &pin);
+               di_downgrade_lock(dentry, AuLock_IR);
+               if (unlikely(err))
+                       goto out_unlock;
+               au_unpin(&pin);
+       } else if (!mmapped)
+               di_downgrade_lock(dentry, AuLock_IR);
+
+       h_file = au_h_fptr(file, au_fbstart(file));
+       if (au_test_fs_bad_mapping(h_file->f_dentry->d_sb)) {
+               /*
+                * by this assignment, f_mapping will differs from aufs inode
+                * i_mapping.
+                * if someone else mixes the use of f_dentry->d_inode and
+                * f_mapping->host, then a problem may arise.
+                */
+               file->f_mapping = h_file->f_mapping;
+       }
+
+       vm_ops = NULL;
+       if (!mmapped) {
+               vm_ops = au_vm_ops(h_file, vma);
+               err = PTR_ERR(vm_ops);
+               if (IS_ERR(vm_ops))
+                       goto out_unlock;
+       }
+
+       /*
+        * unnecessary to handle MAP_DENYWRITE and deny_write_access()?
+        * currently MAP_DENYWRITE from userspace is ignored, but elf loader
+        * sets it. when FMODE_EXEC is set (by open_exec() or sys_uselib()),
+        * both of the aufs file and the lower file is deny_write_access()-ed.
+        * finally I hope we can skip handlling MAP_DENYWRITE here.
+        */
+       err = generic_file_mmap(file, vma);
+       if (unlikely(err))
+               goto out_unlock;
+       vma->vm_ops = &aufs_vm_ops;
+       /* test again */
+       if (!au_test_mmapped(file))
+               au_fi(file)->fi_h_vm_ops = vm_ops;
+
+       vfsub_file_accessed(h_file);
+       fsstack_copy_attr_atime(dentry->d_inode, h_file->f_dentry->d_inode);
+
+ out_unlock:
+       di_read_unlock(dentry, AuLock_IR);
+       if (!wlock && mmapped)
+               fi_read_unlock(file);
+       else
+               fi_write_unlock(file);
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static unsigned int aufs_poll(struct file *file, poll_table *wait)
+{
+       unsigned int mask;
+       int err;
+       struct file *h_file;
+       struct dentry *dentry;
+       struct super_block *sb;
+
+       /* We should pretend an error happened. */
+       mask = POLLERR /* | POLLIN | POLLOUT */;
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/0);
+       if (unlikely(err))
+               goto out;
+
+       /* it is not an error if h_file has no operation */
+       mask = DEFAULT_POLLMASK;
+       h_file = au_h_fptr(file, au_fbstart(file));
+       if (h_file->f_op && h_file->f_op->poll)
+               mask = h_file->f_op->poll(h_file, wait);
+
+       di_read_unlock(dentry, AuLock_IR);
+       fi_read_unlock(file);
+
+ out:
+       si_read_unlock(sb);
+       AuTraceErr((int)mask);
+       return mask;
+}
+
+static int aufs_fsync_nondir(struct file *file, struct dentry *dentry,
+                            int datasync)
+{
+       int err;
+       struct au_pin pin;
+       struct inode *inode;
+       struct file *h_file;
+       struct super_block *sb;
+
+       inode = dentry->d_inode;
+       IMustLock(file->f_mapping->host);
+       if (inode != file->f_mapping->host) {
+               mutex_unlock(&file->f_mapping->host->i_mutex);
+               mutex_lock(&inode->i_mutex);
+       }
+       IMustLock(inode);
+
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+
+       err = 0; /* -EBADF; */ /* posix? */
+       if (unlikely(!(file->f_mode & FMODE_WRITE)))
+               goto out;
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/1);
+       if (unlikely(err))
+               goto out;
+
+       err = au_ready_to_write(file, -1, &pin);
+       di_downgrade_lock(dentry, AuLock_IR);
+       if (unlikely(err))
+               goto out_unlock;
+       au_unpin(&pin);
+
+       err = -EINVAL;
+       h_file = au_h_fptr(file, au_fbstart(file));
+       if (h_file->f_op && h_file->f_op->fsync) {
+               struct dentry *h_d;
+               struct mutex *h_mtx;
+
+               /*
+                * no filemap_fdatawrite() since aufs file has no its own
+                * mapping, but dir.
+                */
+               h_d = h_file->f_dentry;
+               h_mtx = &h_d->d_inode->i_mutex;
+               mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+               err = h_file->f_op->fsync(h_file, h_d, datasync);
+               if (!err)
+                       vfsub_update_h_iattr(&h_file->f_path, /*did*/NULL);
+               /*ignore*/
+               au_cpup_attr_timesizes(inode);
+               mutex_unlock(h_mtx);
+       }
+
+ out_unlock:
+       di_read_unlock(dentry, AuLock_IR);
+       fi_write_unlock(file);
+ out:
+       si_read_unlock(sb);
+       if (inode != file->f_mapping->host) {
+               mutex_unlock(&inode->i_mutex);
+               mutex_lock(&file->f_mapping->host->i_mutex);
+       }
+       return err;
+}
+
+static int aufs_fasync(int fd, struct file *file, int flag)
+{
+       int err;
+       struct file *h_file;
+       struct dentry *dentry;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_reval_and_lock_fdi(file, au_reopen_nondir, /*wlock*/0);
+       if (unlikely(err))
+               goto out;
+
+       h_file = au_h_fptr(file, au_fbstart(file));
+       if (h_file->f_op && h_file->f_op->fasync)
+               err = h_file->f_op->fasync(fd, h_file, flag);
+
+       di_read_unlock(dentry, AuLock_IR);
+       fi_read_unlock(file);
+
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+const struct file_operations aufs_file_fop = {
+       /*
+        * while generic_file_llseek/_unlocked() don't use BKL,
+        * don't use it since it operates file->f_mapping->host.
+        * in aufs, it may be a real file and may confuse users by UDBA.
+        */
+       /* .llseek              = generic_file_llseek, */
+
+       .read           = aufs_read,
+       .write          = aufs_write,
+       .poll           = aufs_poll,
+       .mmap           = aufs_mmap,
+       .open           = aufs_open_nondir,
+       .flush          = aufs_flush,
+       .release        = aufs_release_nondir,
+       .fsync          = aufs_fsync_nondir,
+       .fasync         = aufs_fasync,
+       .splice_write   = aufs_splice_write,
+       .splice_read    = aufs_splice_read
+};
diff --git a/fs/aufs/file.c b/fs/aufs/file.c
new file mode 100644
index 0000000..d472587
--- /dev/null
+++ b/fs/aufs/file.c
@@ -0,0 +1,557 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * handling file/dir, and address_space operation
+ */
+
+#include <linux/fsnotify.h>
+#include <linux/pagemap.h>
+#include "aufs.h"
+
+/*
+ * a dirty trick for handling deny_write_access().
+ * because FMODE_EXEC flag is not passed to f_op->open(),
+ * set it to file->private_data temporary.
+ */
+void au_store_oflag(struct nameidata *nd, struct inode *inode)
+{
+       if (nd
+           /* && !(nd->flags & LOOKUP_CONTINUE) */
+           && (nd->flags & LOOKUP_OPEN)
+           && (nd->intent.open.flags & vfsub_fmode_to_uint(FMODE_EXEC))
+           && inode
+           && S_ISREG(inode->i_mode)) {
+               /* suppress a warning in lp64 */
+               unsigned long flags = nd->intent.open.flags;
+               nd->intent.open.file->private_data = (void *)flags;
+               /* smp_mb(); */
+       }
+}
+
+/* drop flags for writing */
+unsigned int au_file_roflags(unsigned int flags)
+{
+       flags &= ~(O_WRONLY | O_RDWR | O_APPEND | O_CREAT | O_TRUNC);
+       flags |= O_RDONLY | O_NOATIME;
+       return flags;
+}
+
+/* common functions to regular file and dir */
+struct file *au_h_open(struct dentry *dentry, aufs_bindex_t bindex, int flags,
+                      struct file *file)
+{
+       struct file *h_file;
+       struct dentry *h_dentry;
+       struct inode *h_inode;
+       struct super_block *sb;
+       struct au_branch *br;
+       int err;
+
+       h_dentry = au_h_dptr(dentry, bindex);
+       h_inode = h_dentry->d_inode;
+       /* a race condition can happen between open and unlink/rmdir */
+       h_file = ERR_PTR(-ENOENT);
+       if (unlikely((!d_unhashed(dentry) && d_unhashed(h_dentry))
+                    || !h_inode))
+               goto out;
+
+       sb = dentry->d_sb;
+       br = au_sbr(sb, bindex);
+       h_file = ERR_PTR(-EACCES);
+       if (file && (file->f_mode & FMODE_EXEC)
+           && (br->br_mnt->mnt_flags & MNT_NOEXEC))
+               goto out;
+
+       /* drop flags for writing */
+       if (au_test_ro(sb, bindex, dentry->d_inode))
+               flags = au_file_roflags(flags);
+       flags &= ~O_CREAT;
+       atomic_inc(&br->br_count);
+       h_file = dentry_open(dget(h_dentry), mntget(br->br_mnt), flags,
+                            current_cred());
+       if (IS_ERR(h_file))
+               goto out_br;
+
+       if (file && (file->f_mode & FMODE_EXEC)) {
+               h_file->f_mode |= FMODE_EXEC;
+               err = deny_write_access(h_file);
+               if (unlikely(err)) {
+                       fput(h_file);
+                       h_file = ERR_PTR(err);
+                       goto out_br;
+               }
+       }
+       fsnotify_open(h_dentry);
+       goto out; /* success */
+
+ out_br:
+       atomic_dec(&br->br_count);
+ out:
+       return h_file;
+}
+
+int au_do_open(struct file *file, int (*open)(struct file *file, int flags))
+{
+       int err;
+       struct dentry *dentry;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_finfo_init(file);
+       if (unlikely(err))
+               goto out;
+
+       di_read_lock_child(dentry, AuLock_IR);
+       err = open(file, file->f_flags);
+       di_read_unlock(dentry, AuLock_IR);
+
+       fi_write_unlock(file);
+       if (unlikely(err))
+               au_finfo_fin(file);
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+int au_reopen_nondir(struct file *file)
+{
+       int err;
+       aufs_bindex_t bstart, bindex, bend;
+       struct dentry *dentry;
+       struct file *h_file, *h_file_tmp;
+
+       dentry = file->f_dentry;
+       bstart = au_dbstart(dentry);
+       h_file_tmp = NULL;
+       if (au_fbstart(file) == bstart) {
+               h_file = au_h_fptr(file, bstart);
+               if (file->f_mode == h_file->f_mode)
+                       return 0; /* success */
+               h_file_tmp = h_file;
+               get_file(h_file_tmp);
+               au_set_h_fptr(file, bstart, NULL);
+       }
+       AuDebugOn(au_fbstart(file) < bstart
+                 || au_fi(file)->fi_hfile[0 + bstart].hf_file);
+
+       h_file = au_h_open(dentry, bstart, file->f_flags & ~O_TRUNC, file);
+       err = PTR_ERR(h_file);
+       if (IS_ERR(h_file))
+               goto out; /* todo: close all? */
+
+       err = 0;
+       au_set_fbstart(file, bstart);
+       au_set_h_fptr(file, bstart, h_file);
+       au_update_figen(file);
+       /* todo: necessary? */
+       /* file->f_ra = h_file->f_ra; */
+
+       /* close lower files */
+       bend = au_fbend(file);
+       for (bindex = bstart + 1; bindex <= bend; bindex++)
+               au_set_h_fptr(file, bindex, NULL);
+       au_set_fbend(file, bstart);
+
+ out:
+       if (h_file_tmp)
+               fput(h_file_tmp);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_reopen_wh(struct file *file, aufs_bindex_t btgt,
+                       struct dentry *hi_wh)
+{
+       int err;
+       aufs_bindex_t bstart;
+       struct au_dinfo *dinfo;
+       struct dentry *h_dentry;
+
+       dinfo = au_di(file->f_dentry);
+       bstart = dinfo->di_bstart;
+       dinfo->di_bstart = btgt;
+       h_dentry = dinfo->di_hdentry[0 + btgt].hd_dentry;
+       dinfo->di_hdentry[0 + btgt].hd_dentry = hi_wh;
+       err = au_reopen_nondir(file);
+       dinfo->di_hdentry[0 + btgt].hd_dentry = h_dentry;
+       dinfo->di_bstart = bstart;
+
+       return err;
+}
+
+static int au_ready_to_write_wh(struct file *file, loff_t len,
+                               aufs_bindex_t bcpup)
+{
+       int err;
+       struct inode *inode;
+       struct dentry *dentry, *hi_wh;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       inode = dentry->d_inode;
+       hi_wh = au_hi_wh(inode, bcpup);
+       if (!hi_wh)
+               err = au_sio_cpup_wh(dentry, bcpup, len, file);
+       else
+               /* already copied-up after unlink */
+               err = au_reopen_wh(file, bcpup, hi_wh);
+
+       sb = dentry->d_sb;
+       if (!err && inode->i_nlink > 1 && au_opt_test(au_mntflags(sb), PLINK))
+               au_plink_append(inode, bcpup, au_h_dptr(dentry, bcpup));
+
+       return err;
+}
+
+/*
+ * prepare the @file for writing.
+ */
+int au_ready_to_write(struct file *file, loff_t len, struct au_pin *pin)
+{
+       int err;
+       aufs_bindex_t bstart, bcpup;
+       struct dentry *dentry, *parent, *h_dentry;
+       struct inode *h_inode, *inode;
+       struct super_block *sb;
+
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       bstart = au_fbstart(file);
+       inode = dentry->d_inode;
+       err = au_test_ro(sb, bstart, inode);
+       if (!err && (au_h_fptr(file, bstart)->f_mode & FMODE_WRITE)) {
+               err = au_pin(pin, dentry, bstart, AuOpt_UDBA_NONE, /*flags*/0);
+               goto out;
+       }
+
+       /* need to cpup */
+       parent = dget_parent(dentry);
+       di_write_lock_parent(parent);
+       err = AuWbrCopyup(au_sbi(sb), dentry);
+       bcpup = err;
+       if (unlikely(err < 0))
+               goto out_dgrade;
+       err = 0;
+
+       if (!au_h_dptr(parent, bcpup)) {
+               err = au_cpup_dirs(dentry, bcpup);
+               if (unlikely(err))
+                       goto out_dgrade;
+       }
+
+       err = au_pin(pin, dentry, bcpup, AuOpt_UDBA_NONE,
+                    AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+       if (unlikely(err))
+               goto out_dgrade;
+
+       h_dentry = au_h_fptr(file, bstart)->f_dentry;
+       h_inode = h_dentry->d_inode;
+       mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+       if (d_unhashed(dentry) /* || d_unhashed(h_dentry) */
+           /* || !h_inode->i_nlink */) {
+               err = au_ready_to_write_wh(file, len, bcpup);
+               di_downgrade_lock(parent, AuLock_IR);
+       } else {
+               di_downgrade_lock(parent, AuLock_IR);
+               if (!au_h_dptr(dentry, bcpup))
+                       err = au_sio_cpup_simple(dentry, bcpup, len,
+                                                AuCpup_DTIME);
+               if (!err)
+                       err = au_reopen_nondir(file);
+       }
+       mutex_unlock(&h_inode->i_mutex);
+
+       if (!err) {
+               au_pin_set_parent_lflag(pin, /*lflag*/0);
+               goto out_dput; /* success */
+       }
+       au_unpin(pin);
+       goto out_unlock;
+
+ out_dgrade:
+       di_downgrade_lock(parent, AuLock_IR);
+ out_unlock:
+       di_read_unlock(parent, AuLock_IR);
+ out_dput:
+       dput(parent);
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_file_refresh_by_inode(struct file *file, int *need_reopen)
+{
+       int err;
+       aufs_bindex_t bstart;
+       struct au_pin pin;
+       struct au_finfo *finfo;
+       struct dentry *dentry, *parent, *hi_wh;
+       struct inode *inode;
+       struct super_block *sb;
+
+       err = 0;
+       finfo = au_fi(file);
+       dentry = file->f_dentry;
+       sb = dentry->d_sb;
+       inode = dentry->d_inode;
+       bstart = au_ibstart(inode);
+       if (bstart == finfo->fi_bstart)
+               goto out;
+
+       parent = dget_parent(dentry);
+       if (au_test_ro(sb, bstart, inode)) {
+               di_read_lock_parent(parent, !AuLock_IR);
+               err = AuWbrCopyup(au_sbi(sb), dentry);
+               bstart = err;
+               di_read_unlock(parent, !AuLock_IR);
+               if (unlikely(err < 0))
+                       goto out_parent;
+               err = 0;
+       }
+
+       di_read_lock_parent(parent, AuLock_IR);
+       hi_wh = au_hi_wh(inode, bstart);
+       if (au_opt_test(au_mntflags(sb), PLINK)
+           && au_plink_test(inode)
+           && !d_unhashed(dentry)) {
+               err = au_test_and_cpup_dirs(dentry, bstart);
+               if (unlikely(err))
+                       goto out_unlock;
+
+               /* always superio. */
+               err = au_pin(&pin, dentry, bstart, AuOpt_UDBA_NONE,
+                            AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+               if (!err)
+                       err = au_sio_cpup_simple(dentry, bstart, -1,
+                                                AuCpup_DTIME);
+               au_unpin(&pin);
+       } else if (hi_wh) {
+               /* already copied-up after unlink */
+               err = au_reopen_wh(file, bstart, hi_wh);
+               *need_reopen = 0;
+       }
+
+ out_unlock:
+       di_read_unlock(parent, AuLock_IR);
+ out_parent:
+       dput(parent);
+ out:
+       return err;
+}
+
+static void au_do_refresh_file(struct file *file)
+{
+       aufs_bindex_t bindex, bend, new_bindex, brid;
+       struct au_hfile *p, tmp, *q;
+       struct au_finfo *finfo;
+       struct super_block *sb;
+
+       sb = file->f_dentry->d_sb;
+       finfo = au_fi(file);
+       p = finfo->fi_hfile + finfo->fi_bstart;
+       brid = p->hf_br->br_id;
+       bend = finfo->fi_bend;
+       for (bindex = finfo->fi_bstart; bindex <= bend; bindex++, p++) {
+               if (!p->hf_file)
+                       continue;
+
+               new_bindex = au_br_index(sb, p->hf_br->br_id);
+               if (new_bindex == bindex)
+                       continue;
+               if (new_bindex < 0) {
+                       au_set_h_fptr(file, bindex, NULL);
+                       continue;
+               }
+
+               /* swap two lower inode, and loop again */
+               q = finfo->fi_hfile + new_bindex;
+               tmp = *q;
+               *q = *p;
+               *p = tmp;
+               if (tmp.hf_file) {
+                       bindex--;
+                       p--;
+               }
+       }
+
+       p = finfo->fi_hfile;
+       if (!au_test_mmapped(file) && !d_unhashed(file->f_dentry)) {
+               bend = au_sbend(sb);
+               for (finfo->fi_bstart = 0; finfo->fi_bstart <= bend;
+                    finfo->fi_bstart++, p++)
+                       if (p->hf_file) {
+                               if (p->hf_file->f_dentry
+                                   && p->hf_file->f_dentry->d_inode)
+                                       break;
+                               else
+                                       au_hfput(p, file);
+                       }
+       } else {
+               bend = au_br_index(sb, brid);
+               for (finfo->fi_bstart = 0; finfo->fi_bstart < bend;
+                    finfo->fi_bstart++, p++)
+                       if (p->hf_file)
+                               au_hfput(p, file);
+               bend = au_sbend(sb);
+       }
+
+       p = finfo->fi_hfile + bend;
+       for (finfo->fi_bend = bend; finfo->fi_bend >= finfo->fi_bstart;
+            finfo->fi_bend--, p--)
+               if (p->hf_file) {
+                       if (p->hf_file->f_dentry
+                           && p->hf_file->f_dentry->d_inode)
+                               break;
+                       else
+                               au_hfput(p, file);
+               }
+       AuDebugOn(finfo->fi_bend < finfo->fi_bstart);
+}
+
+/*
+ * after branch manipulating, refresh the file.
+ */
+static int refresh_file(struct file *file, int (*reopen)(struct file *file))
+{
+       int err, need_reopen;
+       struct dentry *dentry;
+       aufs_bindex_t bend, bindex;
+
+       dentry = file->f_dentry;
+       err = au_fi_realloc(au_fi(file), au_sbend(dentry->d_sb) + 1);
+       if (unlikely(err))
+               goto out;
+       au_do_refresh_file(file);
+
+       err = 0;
+       need_reopen = 1;
+       if (!au_test_mmapped(file))
+               err = au_file_refresh_by_inode(file, &need_reopen);
+       if (!err && need_reopen && !d_unhashed(dentry))
+               err = reopen(file);
+       if (!err) {
+               au_update_figen(file);
+               return 0; /* success */
+       }
+
+       /* error, close all lower files */
+       bend = au_fbend(file);
+       for (bindex = au_fbstart(file); bindex <= bend; bindex++)
+               au_set_h_fptr(file, bindex, NULL);
+
+ out:
+       return err;
+}
+
+/* common function to regular file and dir */
+int au_reval_and_lock_fdi(struct file *file, int (*reopen)(struct file *file),
+                         int wlock)
+{
+       int err;
+       unsigned int sigen, figen;
+       aufs_bindex_t bstart;
+       unsigned char pseudo_link;
+       struct dentry *dentry;
+
+       err = 0;
+       dentry = file->f_dentry;
+       sigen = au_sigen(dentry->d_sb);
+       fi_write_lock(file);
+       figen = au_figen(file);
+       di_write_lock_child(dentry);
+       bstart = au_dbstart(dentry);
+       pseudo_link = (bstart != au_ibstart(dentry->d_inode));
+       if (sigen == figen && !pseudo_link && au_fbstart(file) == bstart) {
+               if (!wlock) {
+                       di_downgrade_lock(dentry, AuLock_IR);
+                       fi_downgrade_lock(file);
+               }
+               goto out; /* success */
+       }
+
+       AuDbg("sigen %d, figen %d\n", sigen, figen);
+       if (sigen != au_digen(dentry)
+           || sigen != au_iigen(dentry->d_inode)) {
+               err = au_reval_dpath(dentry, sigen);
+               if (unlikely(err < 0))
+                       goto out;
+               AuDebugOn(au_digen(dentry) != sigen
+                         || au_iigen(dentry->d_inode) != sigen);
+       }
+
+       err = refresh_file(file, reopen);
+       if (!err) {
+               if (!wlock) {
+                       di_downgrade_lock(dentry, AuLock_IR);
+                       fi_downgrade_lock(file);
+               }
+       } else {
+               di_write_unlock(dentry);
+               fi_write_unlock(file);
+       }
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* cf. aufs_nopage() */
+/* for madvise(2) */
+static int aufs_readpage(struct file *file __maybe_unused, struct page *page)
+{
+       unlock_page(page);
+       return 0;
+}
+
+/* they will never be called. */
+#ifdef CONFIG_AUFS_DEBUG
+static int aufs_write_begin(struct file *file, struct address_space *mapping,
+                           loff_t pos, unsigned len, unsigned flags,
+                           struct page **pagep, void **fsdata)
+{ AuUnsupport(); return 0; }
+static int aufs_write_end(struct file *file, struct address_space *mapping,
+                         loff_t pos, unsigned len, unsigned copied,
+                         struct page *page, void *fsdata)
+{ AuUnsupport(); return 0; }
+static int aufs_writepage(struct page *page, struct writeback_control *wbc)
+{ AuUnsupport(); return 0; }
+static void aufs_sync_page(struct page *page)
+{ AuUnsupport(); }
+
+static int aufs_set_page_dirty(struct page *page)
+{ AuUnsupport(); return 0; }
+static void aufs_invalidatepage(struct page *page, unsigned long offset)
+{ AuUnsupport(); }
+static int aufs_releasepage(struct page *page, gfp_t gfp)
+{ AuUnsupport(); return 0; }
+static ssize_t aufs_direct_IO(int rw, struct kiocb *iocb,
+                             const struct iovec *iov, loff_t offset,
+                             unsigned long nr_segs)
+{ AuUnsupport(); return 0; }
+#endif /* CONFIG_AUFS_DEBUG */
+
+struct address_space_operations aufs_aop = {
+       .readpage       = aufs_readpage,
+#ifdef CONFIG_AUFS_DEBUG
+       .writepage      = aufs_writepage,
+       .sync_page      = aufs_sync_page,
+       .set_page_dirty = aufs_set_page_dirty,
+       .write_begin    = aufs_write_begin,
+       .write_end      = aufs_write_end,
+       .invalidatepage = aufs_invalidatepage,
+       .releasepage    = aufs_releasepage,
+       .direct_IO      = aufs_direct_IO,
+#endif /* CONFIG_AUFS_DEBUG */
+};
diff --git a/fs/aufs/file.h b/fs/aufs/file.h
new file mode 100644
index 0000000..dd9ee61
--- /dev/null
+++ b/fs/aufs/file.h
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * file operations
+ */
+
+#ifndef __AUFS_FILE_H__
+#define __AUFS_FILE_H__
+
+#ifdef __KERNEL__
+
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/aufs_type.h>
+#include "rwsem.h"
+
+struct au_branch;
+struct au_hfile {
+       struct file             *hf_file;
+       struct au_branch        *hf_br;
+};
+
+struct au_vdir;
+struct au_finfo {
+       atomic_t                fi_generation;
+
+       struct rw_semaphore     fi_rwsem;
+       struct au_hfile         *fi_hfile;
+       aufs_bindex_t           fi_bstart, fi_bend;
+
+       union {
+               /* non-dir only */
+               struct vm_operations_struct     *fi_h_vm_ops;
+
+               /* dir only */
+               struct {
+                       struct au_vdir          *fi_vdir_cache;
+                       int                     fi_maintain_plink;
+               };
+       };
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* file.c */
+extern struct address_space_operations aufs_aop;
+void au_store_oflag(struct nameidata *nd, struct inode *inode);
+unsigned int au_file_roflags(unsigned int flags);
+struct file *au_h_open(struct dentry *dentry, aufs_bindex_t bindex, int flags,
+                      struct file *file);
+int au_do_open(struct file *file, int (*open)(struct file *file, int flags));
+int au_reopen_nondir(struct file *file);
+struct au_pin;
+int au_ready_to_write(struct file *file, loff_t len, struct au_pin *pin);
+int au_reval_and_lock_fdi(struct file *file, int (*reopen)(struct file *file),
+                         int wlock);
+
+/* f_op.c */
+extern const struct file_operations aufs_file_fop;
+int aufs_flush(struct file *file, fl_owner_t id);
+
+/* finfo.c */
+void au_hfput(struct au_hfile *hf, struct file *file);
+void au_set_h_fptr(struct file *file, aufs_bindex_t bindex,
+                  struct file *h_file);
+
+void au_update_figen(struct file *file);
+
+void au_finfo_fin(struct file *file);
+int au_finfo_init(struct file *file);
+int au_fi_realloc(struct au_finfo *finfo, int nbr);
+
+/* ---------------------------------------------------------------------- */
+
+static inline struct au_finfo *au_fi(struct file *file)
+{
+       return file->private_data;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * fi_read_lock, fi_write_lock,
+ * fi_read_unlock, fi_write_unlock, fi_downgrade_lock
+ */
+AuSimpleRwsemFuncs(fi, struct file *f, &au_fi(f)->fi_rwsem);
+
+#define FiMustNoWaiters(f)     AuRwMustNoWaiters(&au_fi(f)->fi_rwsem)
+
+/* ---------------------------------------------------------------------- */
+
+/* todo: hard/soft set? */
+static inline aufs_bindex_t au_fbstart(struct file *file)
+{
+       return au_fi(file)->fi_bstart;
+}
+
+static inline aufs_bindex_t au_fbend(struct file *file)
+{
+       return au_fi(file)->fi_bend;
+}
+
+static inline struct au_vdir *au_fvdir_cache(struct file *file)
+{
+       return au_fi(file)->fi_vdir_cache;
+}
+
+static inline void au_set_fbstart(struct file *file, aufs_bindex_t bindex)
+{
+       au_fi(file)->fi_bstart = bindex;
+}
+
+static inline void au_set_fbend(struct file *file, aufs_bindex_t bindex)
+{
+       au_fi(file)->fi_bend = bindex;
+}
+
+static inline void au_set_fvdir_cache(struct file *file,
+                                     struct au_vdir *vdir_cache)
+{
+       au_fi(file)->fi_vdir_cache = vdir_cache;
+}
+
+static inline struct file *au_h_fptr(struct file *file, aufs_bindex_t bindex)
+{
+       return au_fi(file)->fi_hfile[0 + bindex].hf_file;
+}
+
+/* todo: memory barrier? */
+static inline unsigned int au_figen(struct file *f)
+{
+       return atomic_read(&au_fi(f)->fi_generation);
+}
+
+static inline int au_test_mmapped(struct file *f)
+{
+       return !!(au_fi(f)->fi_h_vm_ops);
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_FILE_H__ */
diff --git a/fs/aufs/finfo.c b/fs/aufs/finfo.c
new file mode 100644
index 0000000..dfb4851
--- /dev/null
+++ b/fs/aufs/finfo.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * file private data
+ */
+
+#include "aufs.h"
+
+void au_hfput(struct au_hfile *hf, struct file *file)
+{
+       if (file->f_mode & FMODE_EXEC)
+               allow_write_access(hf->hf_file);
+       fput(hf->hf_file);
+       hf->hf_file = NULL;
+       atomic_dec(&hf->hf_br->br_count);
+       hf->hf_br = NULL;
+}
+
+void au_set_h_fptr(struct file *file, aufs_bindex_t bindex, struct file *val)
+{
+       struct au_finfo *finfo = au_fi(file);
+       struct au_hfile *hf;
+
+       hf = finfo->fi_hfile + bindex;
+       if (hf->hf_file)
+               au_hfput(hf, file);
+       if (val) {
+               hf->hf_file = val;
+               hf->hf_br = au_sbr(file->f_dentry->d_sb, bindex);
+       }
+}
+
+void au_update_figen(struct file *file)
+{
+       atomic_set(&au_fi(file)->fi_generation, au_digen(file->f_dentry));
+       /* smp_mb(); */ /* atomic_set */
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_finfo_fin(struct file *file)
+{
+       struct au_finfo *finfo;
+       aufs_bindex_t bindex, bend;
+
+       fi_write_lock(file);
+       bend = au_fbend(file);
+       bindex = au_fbstart(file);
+       if (bindex >= 0)
+               /*
+                * calls fput() instead of filp_close(),
+                * since no dnotify or lock for the lower file.
+                */
+               for (; bindex <= bend; bindex++)
+                       au_set_h_fptr(file, bindex, NULL);
+
+       finfo = au_fi(file);
+       au_dbg_verify_hf(finfo);
+       kfree(finfo->fi_hfile);
+       fi_write_unlock(file);
+       au_rwsem_destroy(&finfo->fi_rwsem);
+       au_cache_free_finfo(finfo);
+}
+
+int au_finfo_init(struct file *file)
+{
+       struct au_finfo *finfo;
+       struct dentry *dentry;
+       unsigned long ul;
+
+       dentry = file->f_dentry;
+       finfo = au_cache_alloc_finfo();
+       if (unlikely(!finfo))
+               goto out;
+
+       finfo->fi_hfile = kcalloc(au_sbend(dentry->d_sb) + 1,
+                                 sizeof(*finfo->fi_hfile), GFP_NOFS);
+       if (unlikely(!finfo->fi_hfile))
+               goto out_finfo;
+
+       init_rwsem(&finfo->fi_rwsem);
+       down_write(&finfo->fi_rwsem);
+       finfo->fi_bstart = -1;
+       finfo->fi_bend = -1;
+       atomic_set(&finfo->fi_generation, au_digen(dentry));
+       /* smp_mb(); */ /* atomic_set */
+
+       /* cf. au_store_oflag() */
+       /* suppress a warning in lp64 */
+       ul = (unsigned long)file->private_data;
+       file->f_mode |= (vfsub_uint_to_fmode(ul) & FMODE_EXEC);
+       file->private_data = finfo;
+       return 0; /* success */
+
+ out_finfo:
+       au_cache_free_finfo(finfo);
+ out:
+       return -ENOMEM;
+}
+
+int au_fi_realloc(struct au_finfo *finfo, int nbr)
+{
+       int err, sz;
+       struct au_hfile *hfp;
+
+       err = -ENOMEM;
+       sz = sizeof(*hfp) * (finfo->fi_bend + 1);
+       if (!sz)
+               sz = sizeof(*hfp);
+       hfp = au_kzrealloc(finfo->fi_hfile, sz, sizeof(*hfp) * nbr, GFP_NOFS);
+       if (hfp) {
+               finfo->fi_hfile = hfp;
+               err = 0;
+       }
+
+       return err;
+}
diff --git a/fs/aufs/fstype.h b/fs/aufs/fstype.h
new file mode 100644
index 0000000..54896c6
--- /dev/null
+++ b/fs/aufs/fstype.h
@@ -0,0 +1,464 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * judging filesystem type
+ */
+
+#ifndef __AUFS_FSTYPE_H__
+#define __AUFS_FSTYPE_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/cramfs_fs.h>
+#include <linux/magic.h>
+#include <linux/romfs_fs.h>
+#include <linux/aufs_type.h>
+
+static inline int au_test_aufs(struct super_block *sb)
+{
+       return sb->s_magic == AUFS_SUPER_MAGIC;
+}
+
+static inline const char *au_sbtype(struct super_block *sb)
+{
+       return sb->s_type->name;
+}
+
+static inline int au_test_iso9660(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_ROMFS_FS) || defined(CONFIG_ROMFS_FS_MODULE)
+       return sb->s_magic == ROMFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_romfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_ISO9660_FS) || defined(CONFIG_ISO9660_FS_MODULE)
+       return sb->s_magic == ISOFS_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_cramfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_CRAMFS) || defined(CONFIG_CRAMFS_MODULE)
+       return sb->s_magic == CRAMFS_MAGIC;
+#endif
+       return 0;
+}
+
+static inline int au_test_nfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_NFS_FS) || defined(CONFIG_NFS_FS_MODULE)
+       return sb->s_magic == NFS_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_fuse(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_FUSE_FS) || defined(CONFIG_FUSE_FS_MODULE)
+       return sb->s_magic == FUSE_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_xfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_XFS_FS) || defined(CONFIG_XFS_FS_MODULE)
+       return sb->s_magic == XFS_SB_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_tmpfs(struct super_block *sb __maybe_unused)
+{
+#ifdef CONFIG_TMPFS
+       return sb->s_magic == TMPFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_ecryptfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_ECRYPT_FS) || defined(CONFIG_ECRYPT_FS_MODULE)
+       return !strcmp(au_sbtype(sb), "ecryptfs");
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_smbfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_SMB_FS) || defined(CONFIG_SMB_FS_MODULE)
+       return sb->s_magic == SMB_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_ocfs2(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_OCFS2_FS) || defined(CONFIG_OCFS2_FS_MODULE)
+       return sb->s_magic == OCFS2_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_ocfs2_dlmfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_OCFS2_FS_O2CB) || defined(CONFIG_OCFS2_FS_O2CB_MODULE)
+       return sb->s_magic == DLMFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_coda(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_CODA_FS) || defined(CONFIG_CODA_FS_MODULE)
+       return sb->s_magic == CODA_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_v9fs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_9P_FS) || defined(CONFIG_9P_FS_MODULE)
+       return sb->s_magic == V9FS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_ext4(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_EXT4DEV_FS) || defined(CONFIG_EXT4DEV_FS_MODULE)
+       return sb->s_magic == EXT4_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_sysv(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_SYSV_FS) || defined(CONFIG_SYSV_FS_MODULE)
+       return !strcmp(au_sbtype(sb), "sysv");
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_ramfs(struct super_block *sb)
+{
+       return sb->s_magic == RAMFS_MAGIC;
+}
+
+static inline int au_test_ubifs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_UBIFS_FS) || defined(CONFIG_UBIFS_FS_MODULE)
+       return sb->s_magic == UBIFS_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_procfs(struct super_block *sb __maybe_unused)
+{
+#ifdef CONFIG_PROC_FS
+       return sb->s_magic == PROC_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_sysfs(struct super_block *sb __maybe_unused)
+{
+#ifdef CONFIG_SYSFS
+       return sb->s_magic == SYSFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_configfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_CONFIGFS_FS) || defined(CONFIG_CONFIGFS_FS_MODULE)
+       return sb->s_magic == CONFIGFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_minix(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_MINIX_FS) || defined(CONFIG_MINIX_FS_MODULE)
+       return sb->s_magic == MINIX3_SUPER_MAGIC
+               || sb->s_magic == MINIX2_SUPER_MAGIC
+               || sb->s_magic == MINIX2_SUPER_MAGIC2
+               || sb->s_magic == MINIX_SUPER_MAGIC
+               || sb->s_magic == MINIX_SUPER_MAGIC2;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_cifs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_CIFS_FS) || defined(CONFIGCIFS_FS_MODULE)
+       return sb->s_magic == CIFS_MAGIC_NUMBER;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_fat(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_FAT_FS) || defined(CONFIG_FAT_FS_MODULE)
+       return sb->s_magic == MSDOS_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_msdos(struct super_block *sb)
+{
+       return au_test_fat(sb);
+}
+
+static inline int au_test_vfat(struct super_block *sb)
+{
+       return au_test_fat(sb);
+}
+
+static inline int au_test_securityfs(struct super_block *sb __maybe_unused)
+{
+#ifdef CONFIG_SECURITYFS
+       return sb->s_magic == SECURITYFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_squashfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_SQUASHFS) || defined(CONFIG_SQUASHFS_MODULE)
+       return sb->s_magic == SQUASHFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_btrfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_BTRFS_FS) || defined(CONFIG_BTRFS_FS_MODULE)
+       return sb->s_magic == BTRFS_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_xenfs(struct super_block *sb __maybe_unused)
+{
+#if defined(CONFIG_XENFS) || defined(CONFIG_XENFS_MODULE)
+       return sb->s_magic == XENFS_SUPER_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+static inline int au_test_debugfs(struct super_block *sb __maybe_unused)
+{
+#ifdef CONFIG_DEBUG_FS
+       return sb->s_magic == DEBUGFS_MAGIC;
+#else
+       return 0;
+#endif
+}
+
+/* ---------------------------------------------------------------------- */
+/*
+ * they can't be an aufs branch.
+ */
+static inline int au_test_fs_unsuppoted(struct super_block *sb)
+{
+       return
+#ifndef CONFIG_AUFS_BR_RAMFS
+               au_test_ramfs(sb) ||
+#endif
+               au_test_procfs(sb)
+               || au_test_sysfs(sb)
+               || au_test_configfs(sb)
+               || au_test_debugfs(sb)
+               || au_test_securityfs(sb)
+               || au_test_xenfs(sb)
+               /* || !strcmp(au_sbtype(sb), "unionfs") */
+               || au_test_aufs(sb); /* will be supported in next version */
+}
+
+/*
+ * If the filesystem supports NFS-export, then it has to support NULL as
+ * a nameidata parameter for ->create(), ->lookup() and ->d_revalidate().
+ * We can apply this principle when we handle a lower filesystem.
+ */
+static inline int au_test_fs_null_nd(struct super_block *sb)
+{
+       return !!sb->s_export_op;
+}
+
+static inline int au_test_fs_remote(struct super_block *sb)
+{
+       return !au_test_tmpfs(sb)
+#ifdef CONFIG_AUFS_BR_RAMFS
+               && !au_test_ramfs(sb)
+#endif
+               && !(sb->s_type->fs_flags & FS_REQUIRES_DEV);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * Note: these functions (below) are created after reading ->getattr() in all
+ * filesystems under linux/fs. it means we have to do so in every update...
+ */
+
+/*
+ * some filesystems require getattr to refresh the inode attributes before
+ * referencing.
+ * in most cases, we can rely on the inode attribute in NFS (or every remote fs)
+ * and leave the work for d_revalidate()
+ */
+static inline int au_test_fs_refresh_iattr(struct super_block *sb)
+{
+       return au_test_nfs(sb)
+               || au_test_fuse(sb)
+               /* || au_test_smbfs(sb) */      /* untested */
+               /* || au_test_ocfs2(sb) */      /* untested */
+               /* || au_test_btrfs(sb) */      /* untested */
+               /* || au_test_coda(sb) */       /* untested */
+               /* || au_test_v9fs(sb) */       /* untested */
+               ;
+}
+
+/*
+ * filesystems which don't maintain i_size or i_blocks.
+ */
+static inline int au_test_fs_bad_iattr_size(struct super_block *sb)
+{
+       return au_test_xfs(sb)
+               /* || au_test_ext4(sb) */       /* untested */
+               /* || au_test_ocfs2(sb) */      /* untested */
+               /* || au_test_ocfs2_dlmfs(sb) */ /* untested */
+               /* || au_test_sysv(sb) */       /* untested */
+               /* || au_test_ubifs(sb) */      /* untested */
+               /* || au_test_minix(sb) */      /* untested */
+               ;
+}
+
+/*
+ * filesystems which don't store the correct value in some of their inode
+ * attributes.
+ */
+static inline int au_test_fs_bad_iattr(struct super_block *sb)
+{
+       return au_test_fs_bad_iattr_size(sb)
+               /* || au_test_cifs(sb) */       /* untested */
+               || au_test_fat(sb)
+               || au_test_msdos(sb)
+               || au_test_vfat(sb);
+}
+
+/* they don't check i_nlink in link(2) */
+static inline int au_test_fs_no_limit_nlink(struct super_block *sb)
+{
+       return au_test_tmpfs(sb)
+#ifdef CONFIG_AUFS_BR_RAMFS
+               || au_test_ramfs(sb)
+#endif
+               ;
+}
+
+/*
+ * filesystems which sets S_NOATIME and S_NOCMTIME.
+ */
+static inline int au_test_fs_notime(struct super_block *sb)
+{
+       return au_test_nfs(sb)
+               || au_test_fuse(sb)
+               /* || au_test_cifs(sb) */       /* untested */
+               /* || au_test_ubifs(sb) */      /* untested */
+               ;
+}
+
+/*
+ * filesystems which requires replacing i_mapping.
+ */
+static inline int au_test_fs_bad_mapping(struct super_block *sb)
+{
+       return au_test_fuse(sb);
+}
+
+/* temporary support for i#1 in cramfs */
+static inline int au_test_fs_unique_ino(struct inode *inode)
+{
+       if (au_test_cramfs(inode->i_sb))
+               return inode->i_ino != 1;
+       return 1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * the filesystem where the xino files placed must support i/o after unlink and
+ * maintain i_size and i_blocks.
+ */
+static inline int au_test_fs_bad_xino(struct super_block *sb)
+{
+       return au_test_fs_remote(sb)
+               || au_test_fs_bad_iattr_size(sb)
+#ifdef CONFIG_AUFS_BR_RAMFS
+               || !(au_test_ramfs(sb) || au_test_fs_null_nd(sb))
+#else
+               || !au_test_fs_null_nd(sb) /* to keep xino code simple */
+#endif
+               /* don't want unnecessary work for xino */
+               || au_test_aufs(sb)
+               || au_test_ecryptfs(sb);
+}
+
+static inline int au_test_fs_trunc_xino(struct super_block *sb)
+{
+       return au_test_tmpfs(sb)
+               || au_test_ramfs(sb);
+}
+
+/*
+ * test if the @sb is real-readonly.
+ */
+static inline int au_test_fs_rr(struct super_block *sb)
+{
+       return au_test_squashfs(sb)
+               || au_test_iso9660(sb)
+               || au_test_cramfs(sb)
+               || au_test_romfs(sb);
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_FSTYPE_H__ */
diff --git a/fs/aufs/hinotify.c b/fs/aufs/hinotify.c
new file mode 100644
index 0000000..af8ebdb
--- /dev/null
+++ b/fs/aufs/hinotify.c
@@ -0,0 +1,746 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inotify for the lower directories
+ */
+
+#include "aufs.h"
+
+static const __u32 AuHinMask = (IN_MOVE | IN_DELETE | IN_CREATE);
+static struct inotify_handle *au_hin_handle;
+
+AuCacheFuncs(hinotify, HINOTIFY);
+
+int au_hin_alloc(struct au_hinode *hinode, struct inode *inode,
+                struct inode *h_inode)
+{
+       int err;
+       struct au_hinotify *hin;
+       s32 wd;
+
+       err = -ENOMEM;
+       hin = au_cache_alloc_hinotify();
+       if (hin) {
+               AuDebugOn(hinode->hi_notify);
+               hinode->hi_notify = hin;
+               hin->hin_aufs_inode = inode;
+
+               inotify_init_watch(&hin->hin_watch);
+               wd = inotify_add_watch(au_hin_handle, &hin->hin_watch, h_inode,
+                                      AuHinMask);
+               if (wd >= 0)
+                       return 0; /* success */
+
+               err = wd;
+               put_inotify_watch(&hin->hin_watch);
+               au_cache_free_hinotify(hin);
+               hinode->hi_notify = NULL;
+       }
+
+       return err;
+}
+
+void au_hin_free(struct au_hinode *hinode)
+{
+       int err;
+       struct au_hinotify *hin;
+
+       hin = hinode->hi_notify;
+       if (hin) {
+               err = 0;
+               if (atomic_read(&hin->hin_watch.count))
+                       err = inotify_rm_watch(au_hin_handle, &hin->hin_watch);
+               if (unlikely(err))
+                       /* it means the watch is already removed */
+                       AuWarn("failed inotify_rm_watch() %d\n", err);
+               au_cache_free_hinotify(hin);
+               hinode->hi_notify = NULL;
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_hin_ctl(struct au_hinode *hinode, int do_set)
+{
+       struct inode *h_inode;
+       struct inotify_watch *watch;
+
+       if (!hinode->hi_notify)
+               return;
+
+       h_inode = hinode->hi_inode;
+       IMustLock(h_inode);
+
+       /* todo: try inotify_find_update_watch()? */
+       watch = &hinode->hi_notify->hin_watch;
+       mutex_lock(&h_inode->inotify_mutex);
+       /* mutex_lock(&watch->ih->mutex); */
+       if (do_set) {
+               AuDebugOn(watch->mask & AuHinMask);
+               watch->mask |= AuHinMask;
+       } else {
+               AuDebugOn(!(watch->mask & AuHinMask));
+               watch->mask &= ~AuHinMask;
+       }
+       /* mutex_unlock(&watch->ih->mutex); */
+       mutex_unlock(&h_inode->inotify_mutex);
+}
+
+void au_reset_hinotify(struct inode *inode, unsigned int flags)
+{
+       aufs_bindex_t bindex, bend;
+       struct inode *hi;
+       struct dentry *iwhdentry;
+
+       bend = au_ibend(inode);
+       for (bindex = au_ibstart(inode); bindex <= bend; bindex++) {
+               hi = au_h_iptr(inode, bindex);
+               if (!hi)
+                       continue;
+
+               /* mutex_lock_nested(&hi->i_mutex, AuLsc_I_CHILD); */
+               iwhdentry = au_hi_wh(inode, bindex);
+               if (iwhdentry)
+                       dget(iwhdentry);
+               au_igrab(hi);
+               au_set_h_iptr(inode, bindex, NULL, 0);
+               au_set_h_iptr(inode, bindex, au_igrab(hi),
+                             flags & ~AuHi_XINO);
+               iput(hi);
+               dput(iwhdentry);
+               /* mutex_unlock(&hi->i_mutex); */
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int hin_xino(struct inode *inode, struct inode *h_inode)
+{
+       int err;
+       aufs_bindex_t bindex, bend, bfound, bstart;
+       struct inode *h_i;
+
+       err = 0;
+       if (unlikely(inode->i_ino == AUFS_ROOT_INO)) {
+               AuWarn("branch root dir was changed\n");
+               goto out;
+       }
+
+       bfound = -1;
+       bend = au_ibend(inode);
+       bstart = au_ibstart(inode);
+#if 0 /* reserved for future use */
+       if (bindex == bend) {
+               /* keep this ino in rename case */
+               goto out;
+       }
+#endif
+       for (bindex = bstart; bindex <= bend; bindex++) {
+               if (au_h_iptr(inode, bindex) == h_inode) {
+                       bfound = bindex;
+                       break;
+               }
+       }
+       if (bfound < 0)
+               goto out;
+
+       for (bindex = bstart; bindex <= bend; bindex++) {
+               h_i = au_h_iptr(inode, bindex);
+               if (!h_i)
+                       continue;
+
+               err = au_xino_write0(inode->i_sb, bindex, h_i->i_ino, 0);
+               /* ignore this error */
+               /* bad action? */
+       }
+
+       /* children inode number will be broken */
+
+ out:
+       AuTraceErr(err);
+       return err;
+}
+
+static int hin_gen_tree(struct dentry *dentry)
+{
+       int err, i, j, ndentry;
+       struct au_dcsub_pages dpages;
+       struct au_dpage *dpage;
+       struct dentry **dentries;
+
+       err = au_dpages_init(&dpages, GFP_NOFS);
+       if (unlikely(err))
+               goto out;
+       err = au_dcsub_pages(&dpages, dentry, NULL, NULL);
+       if (unlikely(err))
+               goto out_dpages;
+
+       for (i = 0; i < dpages.ndpage; i++) {
+               dpage = dpages.dpages + i;
+               dentries = dpage->dentries;
+               ndentry = dpage->ndentry;
+               for (j = 0; j < ndentry; j++) {
+                       struct dentry *d;
+
+                       d = dentries[j];
+                       if (IS_ROOT(d))
+                               continue;
+
+                       d_drop(d);
+                       au_digen_dec(d);
+                       if (d->d_inode)
+                               /* todo: reset children xino?
+                                  cached children only? */
+                               au_iigen_dec(d->d_inode);
+               }
+       }
+
+ out_dpages:
+       au_dpages_free(&dpages);
+
+       /* discard children */
+       dentry_unhash(dentry);
+       dput(dentry);
+ out:
+       return err;
+}
+
+/*
+ * return 0 if processed.
+ */
+static int hin_gen_by_inode(char *name, unsigned int nlen, struct inode *inode,
+                           const unsigned int isdir)
+{
+       int err;
+       struct dentry *d;
+       struct qstr *dname;
+
+       err = 1;
+       if (unlikely(inode->i_ino == AUFS_ROOT_INO)) {
+               AuWarn("branch root dir was changed\n");
+               err = 0;
+               goto out;
+       }
+
+       if (!isdir) {
+               AuDebugOn(!name);
+               au_iigen_dec(inode);
+               spin_lock(&dcache_lock);
+               list_for_each_entry(d, &inode->i_dentry, d_alias) {
+                       dname = &d->d_name;
+                       if (dname->len != nlen
+                           && memcmp(dname->name, name, nlen))
+                               continue;
+                       err = 0;
+                       spin_lock(&d->d_lock);
+                       __d_drop(d);
+                       au_digen_dec(d);
+                       spin_unlock(&d->d_lock);
+                       break;
+               }
+               spin_unlock(&dcache_lock);
+       } else {
+               au_fset_si(au_sbi(inode->i_sb), FAILED_REFRESH_DIRS);
+               d = d_find_alias(inode);
+               if (!d) {
+                       au_iigen_dec(inode);
+                       goto out;
+               }
+
+               dname = &d->d_name;
+               if (dname->len == nlen && !memcmp(dname->name, name, nlen))
+                       err = hin_gen_tree(d);
+               dput(d);
+       }
+
+ out:
+       AuTraceErr(err);
+       return err;
+}
+
+static int hin_gen_by_name(struct dentry *dentry, const unsigned int isdir)
+{
+       int err;
+       struct inode *inode;
+
+       inode = dentry->d_inode;
+       if (IS_ROOT(dentry)
+           /* || (inode && inode->i_ino == AUFS_ROOT_INO) */
+               ) {
+               AuWarn("branch root dir was changed\n");
+               return 0;
+       }
+
+       err = 0;
+       if (!isdir) {
+               d_drop(dentry);
+               au_digen_dec(dentry);
+               if (inode)
+                       au_iigen_dec(inode);
+       } else {
+               au_fset_si(au_sbi(dentry->d_sb), FAILED_REFRESH_DIRS);
+               if (inode)
+                       err = hin_gen_tree(dentry);
+       }
+
+       AuTraceErr(err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* hinotify job flags */
+#define AuHinJob_XINO0         1
+#define AuHinJob_GEN           (1 << 1)
+#define AuHinJob_DIRENT                (1 << 2)
+#define AuHinJob_ISDIR         (1 << 3)
+#define AuHinJob_TRYXINO0      (1 << 4)
+#define AuHinJob_MNTPNT                (1 << 5)
+#define au_ftest_hinjob(flags, name)   ((flags) & AuHinJob_##name)
+#define au_fset_hinjob(flags, name)    { (flags) |= AuHinJob_##name; }
+#define au_fclr_hinjob(flags, name)    { (flags) &= ~AuHinJob_##name; }
+
+struct hin_job_args {
+       unsigned int flags;
+       struct inode *inode, *h_inode, *dir, *h_dir;
+       struct dentry *dentry;
+       char *h_name;
+       int h_nlen;
+};
+
+static int hin_job(struct hin_job_args *a)
+{
+       const unsigned int isdir = au_ftest_hinjob(a->flags, ISDIR);
+
+       /* reset xino */
+       if (au_ftest_hinjob(a->flags, XINO0) && a->inode)
+               hin_xino(a->inode, a->h_inode); /* ignore this error */
+
+       if (au_ftest_hinjob(a->flags, TRYXINO0)
+           && a->inode
+           && a->h_inode) {
+               mutex_lock_nested(&a->h_inode->i_mutex, AuLsc_I_CHILD);
+               if (!a->h_inode->i_nlink)
+                       hin_xino(a->inode, a->h_inode); /* ignore this error */
+               mutex_unlock(&a->h_inode->i_mutex);
+       }
+
+       /* make the generation obsolete */
+       if (au_ftest_hinjob(a->flags, GEN)) {
+               int err = -1;
+               if (a->inode)
+                       err = hin_gen_by_inode(a->h_name, a->h_nlen, a->inode,
+                                              isdir);
+               if (err && a->dentry)
+                       hin_gen_by_name(a->dentry, isdir);
+               /* ignore this error */
+       }
+
+       /* make dir entries obsolete */
+       if (au_ftest_hinjob(a->flags, DIRENT) && a->inode) {
+               struct au_vdir *vdir;
+
+               vdir = au_ivdir(a->inode);
+               if (vdir)
+                       vdir->vd_jiffy = 0;
+               /* IMustLock(a->inode); */
+               /* a->inode->i_version++; */
+       }
+
+       /* can do nothing but warn */
+       if (au_ftest_hinjob(a->flags, MNTPNT)
+           && a->dentry
+           && d_mountpoint(a->dentry))
+               AuWarn("mount-point %.*s is removed or renamed\n",
+                      AuDLNPair(a->dentry));
+
+       return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static char *in_name(u32 mask)
+{
+#ifdef CONFIG_AUFS_DEBUG
+#define test_ret(flag) if (mask & flag) \
+                               return #flag;
+       test_ret(IN_ACCESS);
+       test_ret(IN_MODIFY);
+       test_ret(IN_ATTRIB);
+       test_ret(IN_CLOSE_WRITE);
+       test_ret(IN_CLOSE_NOWRITE);
+       test_ret(IN_OPEN);
+       test_ret(IN_MOVED_FROM);
+       test_ret(IN_MOVED_TO);
+       test_ret(IN_CREATE);
+       test_ret(IN_DELETE);
+       test_ret(IN_DELETE_SELF);
+       test_ret(IN_MOVE_SELF);
+       test_ret(IN_UNMOUNT);
+       test_ret(IN_Q_OVERFLOW);
+       test_ret(IN_IGNORED);
+       return "";
+#undef test_ret
+#else
+       return "??";
+#endif
+}
+
+static struct dentry *lookup_wlock_by_name(char *name, unsigned int nlen,
+                                          struct inode *dir)
+{
+       struct dentry *dentry, *d, *parent;
+       struct qstr *dname;
+
+       parent = d_find_alias(dir);
+       if (!parent)
+               return NULL;
+
+       dentry = NULL;
+       spin_lock(&dcache_lock);
+       list_for_each_entry(d, &parent->d_subdirs, d_u.d_child) {
+               /* AuDbg("%.*s\n", AuDLNPair(d)); */
+               dname = &d->d_name;
+               if (dname->len != nlen || memcmp(dname->name, name, nlen))
+                       continue;
+               if (!atomic_read(&d->d_count) || !d->d_fsdata) {
+                       spin_lock(&d->d_lock);
+                       __d_drop(d);
+                       spin_unlock(&d->d_lock);
+                       continue;
+               }
+
+               dentry = dget(d);
+               break;
+       }
+       spin_unlock(&dcache_lock);
+       dput(parent);
+
+       if (dentry)
+               di_write_lock_child(dentry);
+
+       return dentry;
+}
+
+static struct inode *lookup_wlock_by_ino(struct super_block *sb,
+                                        aufs_bindex_t bindex, ino_t h_ino)
+{
+       struct inode *inode;
+       ino_t ino;
+       int err;
+
+       inode = NULL;
+       err = au_xino_read(sb, bindex, h_ino, &ino);
+       if (!err && ino)
+               inode = ilookup(sb, ino);
+       if (!inode)
+               goto out;
+
+       if (unlikely(inode->i_ino == AUFS_ROOT_INO)) {
+               AuWarn("wrong root branch\n");
+               iput(inode);
+               inode = NULL;
+               goto out;
+       }
+
+       ii_write_lock_child(inode);
+
+ out:
+       return inode;
+}
+
+enum { CHILD, PARENT };
+struct postproc_args {
+       struct inode *h_dir, *dir, *h_child_inode;
+       u32 mask;
+       unsigned int flags[2];
+       unsigned int h_child_nlen;
+       char h_child_name[];
+};
+
+static void postproc(void *_args)
+{
+       struct postproc_args *a = _args;
+       struct super_block *sb;
+       aufs_bindex_t bindex, bend, bfound;
+       unsigned char xino, try_iput;
+       int err;
+       struct inode *inode;
+       ino_t h_ino;
+       struct hin_job_args args;
+       struct dentry *dentry;
+       struct au_sbinfo *sbinfo;
+
+       AuDebugOn(!_args);
+       AuDebugOn(!a->h_dir);
+       AuDebugOn(!a->dir);
+       AuDebugOn(!a->mask);
+       AuDbg("mask 0x%x %s, i%lu, hi%lu, hci%lu\n",
+             a->mask, in_name(a->mask), a->dir->i_ino, a->h_dir->i_ino,
+             a->h_child_inode ? a->h_child_inode->i_ino : 0);
+
+       inode = NULL;
+       dentry = NULL;
+       /*
+        * do not lock a->dir->i_mutex here
+        * because of d_revalidate() may cause a deadlock.
+        */
+       sb = a->dir->i_sb;
+       AuDebugOn(!sb);
+       sbinfo = au_sbi(sb);
+       AuDebugOn(!sbinfo);
+       /* big aufs lock */
+       si_noflush_write_lock(sb);
+
+       ii_read_lock_parent(a->dir);
+       bfound = -1;
+       bend = au_ibend(a->dir);
+       for (bindex = au_ibstart(a->dir); bindex <= bend; bindex++)
+               if (au_h_iptr(a->dir, bindex) == a->h_dir) {
+                       bfound = bindex;
+                       break;
+               }
+       ii_read_unlock(a->dir);
+       if (unlikely(bfound < 0))
+               goto out;
+
+       xino = !!au_opt_test(au_mntflags(sb), XINO);
+       h_ino = 0;
+       if (a->h_child_inode)
+               h_ino = a->h_child_inode->i_ino;
+
+       if (a->h_child_nlen
+           && (au_ftest_hinjob(a->flags[CHILD], GEN)
+               || au_ftest_hinjob(a->flags[CHILD], MNTPNT)))
+               dentry = lookup_wlock_by_name(a->h_child_name, a->h_child_nlen,
+                                             a->dir);
+       try_iput = 0;
+       if (dentry)
+               inode = dentry->d_inode;
+       if (xino && !inode && h_ino
+           && (au_ftest_hinjob(a->flags[CHILD], XINO0)
+               || au_ftest_hinjob(a->flags[CHILD], TRYXINO0)
+               || au_ftest_hinjob(a->flags[CHILD], GEN))) {
+               inode = lookup_wlock_by_ino(sb, bfound, h_ino);
+               try_iput = 1;
+           }
+
+       args.flags = a->flags[CHILD];
+       args.dentry = dentry;
+       args.inode = inode;
+       args.h_inode = a->h_child_inode;
+       args.dir = a->dir;
+       args.h_dir = a->h_dir;
+       args.h_name = a->h_child_name;
+       args.h_nlen = a->h_child_nlen;
+       err = hin_job(&args);
+       if (dentry) {
+               if (dentry->d_fsdata)
+                       di_write_unlock(dentry);
+               dput(dentry);
+       }
+       if (inode && try_iput) {
+               ii_write_unlock(inode);
+               iput(inode);
+       }
+
+       ii_write_lock_parent(a->dir);
+       args.flags = a->flags[PARENT];
+       args.dentry = NULL;
+       args.inode = a->dir;
+       args.h_inode = a->h_dir;
+       args.dir = NULL;
+       args.h_dir = NULL;
+       args.h_name = NULL;
+       args.h_nlen = 0;
+       err = hin_job(&args);
+       ii_write_unlock(a->dir);
+
+ out:
+       au_nwt_done(&sbinfo->si_nowait);
+       si_write_unlock(sb);
+
+       iput(a->h_child_inode);
+       iput(a->h_dir);
+       iput(a->dir);
+       kfree(a);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void aufs_inotify(struct inotify_watch *watch, u32 wd __maybe_unused,
+                        u32 mask, u32 cookie __maybe_unused,
+                        const char *h_child_name, struct inode *h_child_inode)
+{
+       struct au_hinotify *hinotify;
+       struct postproc_args *args;
+       int len, wkq_err;
+       unsigned char isdir, isroot, wh;
+       char *p;
+       struct inode *dir;
+       unsigned int flags[2];
+
+       /* if IN_UNMOUNT happens, there must be another bug */
+       AuDebugOn(mask & IN_UNMOUNT);
+       if (mask & (IN_IGNORED | IN_UNMOUNT)) {
+               put_inotify_watch(watch);
+               return;
+       }
+#ifdef AuDbgHinotify
+       au_debug(1);
+       if (1 || !h_child_name || strcmp(h_child_name, AUFS_XINO_FNAME)) {
+               AuDbg("i%lu, wd %d, mask 0x%x %s, cookie 0x%x, hcname %s,"
+                     " hi%lu\n",
+                     watch->inode->i_ino, wd, mask, in_name(mask), cookie,
+                     h_child_name ? h_child_name : "",
+                     h_child_inode ? h_child_inode->i_ino : 0);
+               WARN_ON(1);
+       }
+       au_debug(0);
+#endif
+
+       hinotify = container_of(watch, struct au_hinotify, hin_watch);
+       AuDebugOn(!hinotify || !hinotify->hin_aufs_inode);
+       dir = igrab(hinotify->hin_aufs_inode);
+       if (!dir)
+               return;
+
+       isroot = (dir->i_ino == AUFS_ROOT_INO);
+       len = 0;
+       wh = 0;
+       if (h_child_name) {
+               len = strlen(h_child_name);
+               if (!memcmp(h_child_name, AUFS_WH_PFX, AUFS_WH_PFX_LEN)) {
+                       h_child_name += AUFS_WH_PFX_LEN;
+                       len -= AUFS_WH_PFX_LEN;
+                       wh = 1;
+               }
+       }
+
+       isdir = 0;
+       if (h_child_inode)
+               isdir = !!S_ISDIR(h_child_inode->i_mode);
+       flags[PARENT] = AuHinJob_ISDIR;
+       flags[CHILD] = 0;
+       if (isdir)
+               flags[CHILD] = AuHinJob_ISDIR;
+       switch (mask & IN_ALL_EVENTS) {
+       case IN_MOVED_FROM:
+       case IN_MOVED_TO:
+               AuDebugOn(!h_child_name || !h_child_inode);
+               au_fset_hinjob(flags[CHILD], GEN);
+               au_fset_hinjob(flags[CHILD], XINO0);
+               au_fset_hinjob(flags[CHILD], MNTPNT);
+               au_fset_hinjob(flags[PARENT], DIRENT);
+               break;
+
+       case IN_CREATE:
+               AuDebugOn(!h_child_name || !h_child_inode);
+               au_fset_hinjob(flags[PARENT], DIRENT);
+               au_fset_hinjob(flags[CHILD], GEN);
+               break;
+
+       case IN_DELETE:
+               /*
+                * aufs never be able to get this child inode.
+                * revalidation should be in d_revalidate()
+                * by checking i_nlink, i_generation or d_unhashed().
+                */
+               AuDebugOn(!h_child_name);
+               au_fset_hinjob(flags[PARENT], DIRENT);
+               au_fset_hinjob(flags[CHILD], GEN);
+               au_fset_hinjob(flags[CHILD], TRYXINO0);
+               au_fset_hinjob(flags[CHILD], MNTPNT);
+               break;
+
+       default:
+               AuDebugOn(1);
+       }
+
+       if (wh)
+               h_child_inode = NULL;
+
+       /* iput() and kfree() will be called in postproc() */
+       /*
+        * inotify_mutex is already acquired and kmalloc/prune_icache may lock
+        * iprune_mutex. strange.
+        */
+       lockdep_off();
+       args = kmalloc(sizeof(*args) + len + 1, GFP_NOFS);
+       lockdep_on();
+       if (unlikely(!args)) {
+               AuErr1("no memory\n");
+               iput(dir);
+               return;
+       }
+       args->flags[PARENT] = flags[PARENT];
+       args->flags[CHILD] = flags[CHILD];
+       args->mask = mask;
+       args->dir = dir;
+       args->h_dir = igrab(watch->inode);
+       if (h_child_inode)
+               h_child_inode = igrab(h_child_inode); /* can be NULL */
+       args->h_child_inode = h_child_inode;
+       args->h_child_nlen = len;
+       if (len) {
+               p = (void *)args;
+               p += sizeof(*args);
+               memcpy(p, h_child_name, len + 1);
+       }
+
+       lockdep_off();
+       wkq_err = au_wkq_nowait(postproc, args, dir->i_sb);
+       lockdep_on();
+       if (unlikely(wkq_err))
+               AuErr("wkq %d\n", wkq_err);
+}
+
+static void aufs_inotify_destroy(struct inotify_watch *watch __maybe_unused)
+{
+       return;
+}
+
+static struct inotify_operations aufs_inotify_ops = {
+       .handle_event   = aufs_inotify,
+       .destroy_watch  = aufs_inotify_destroy
+};
+
+/* ---------------------------------------------------------------------- */
+
+static void au_hin_destroy_cache(void)
+{
+       kmem_cache_destroy(au_cachep[AuCache_HINOTIFY]);
+       au_cachep[AuCache_HINOTIFY] = NULL;
+}
+
+int __init au_hinotify_init(void)
+{
+       int err;
+
+       err = -ENOMEM;
+       au_cachep[AuCache_HINOTIFY] = AuCache(au_hinotify);
+       if (au_cachep[AuCache_HINOTIFY]) {
+               err = 0;
+               au_hin_handle = inotify_init(&aufs_inotify_ops);
+               if (IS_ERR(au_hin_handle)) {
+                       err = PTR_ERR(au_hin_handle);
+                       au_hin_destroy_cache();
+               }
+       }
+       AuTraceErr(err);
+       return err;
+}
+
+void au_hinotify_fin(void)
+{
+       inotify_destroy(au_hin_handle);
+       if (au_cachep[AuCache_HINOTIFY])
+               au_hin_destroy_cache();
+}
diff --git a/fs/aufs/i_op.c b/fs/aufs/i_op.c
new file mode 100644
index 0000000..a64d6b0
--- /dev/null
+++ b/fs/aufs/i_op.c
@@ -0,0 +1,862 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode operations (except add/del/rename)
+ */
+
+#include <linux/device_cgroup.h>
+#include <linux/fs_stack.h>
+#include <linux/uaccess.h>
+#include "aufs.h"
+
+static int h_permission(struct inode *h_inode, int mask,
+                       struct vfsmount *h_mnt, int brperm)
+{
+       int err;
+       const unsigned char write_mask = !!(mask & (MAY_WRITE | MAY_APPEND));
+
+       err = -EACCES;
+       if ((write_mask && IS_IMMUTABLE(h_inode))
+           || ((mask & MAY_EXEC)
+               && S_ISREG(h_inode->i_mode)
+               && ((h_mnt->mnt_flags & MNT_NOEXEC)
+                   || !(h_inode->i_mode & S_IXUGO))))
+               goto out;
+
+       /*
+        * - skip the lower fs test in the case of write to ro branch.
+        * - nfs dir permission write check is optimized, but a policy for
+        *   link/rename requires a real check.
+        */
+       if ((write_mask && !au_br_writable(brperm))
+           || (au_test_nfs(h_inode->i_sb) && S_ISDIR(h_inode->i_mode)
+               && write_mask && !(mask & MAY_READ))
+           || !h_inode->i_op->permission) {
+               /* AuLabel(generic_permission); */
+               err = generic_permission(h_inode, mask, NULL);
+       } else {
+               /* AuLabel(h_inode->permission); */
+               err = h_inode->i_op->permission(h_inode, mask);
+               AuTraceErr(err);
+       }
+
+       if (!err)
+               err = devcgroup_inode_permission(h_inode, mask);
+       if (!err)
+               err = security_inode_permission
+                       (h_inode, mask & (MAY_READ | MAY_WRITE | MAY_EXEC
+                                         | MAY_APPEND));
+
+ out:
+       return err;
+}
+
+static int aufs_permission(struct inode *inode, int mask)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       const unsigned char isdir = !!S_ISDIR(inode->i_mode);
+       const unsigned char write_mask = !!(mask & (MAY_WRITE | MAY_APPEND));
+       struct inode *h_inode;
+       struct super_block *sb;
+       struct au_branch *br;
+
+       sb = inode->i_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       ii_read_lock_child(inode);
+
+       if (!isdir || write_mask) {
+               h_inode = au_h_iptr(inode, au_ibstart(inode));
+               AuDebugOn(!h_inode
+                         || ((h_inode->i_mode & S_IFMT)
+                             != (inode->i_mode & S_IFMT)));
+               err = 0;
+               bindex = au_ibstart(inode);
+               br = au_sbr(sb, bindex);
+               err = h_permission(h_inode, mask, br->br_mnt, br->br_perm);
+
+               if (write_mask && !err) {
+                       /* test whether the upper writable branch exists */
+                       err = -EROFS;
+                       for (; bindex >= 0; bindex--)
+                               if (!au_br_rdonly(au_sbr(sb, bindex))) {
+                                       err = 0;
+                                       break;
+                               }
+               }
+               goto out;
+       }
+
+       /* non-write to dir */
+       err = 0;
+       bend = au_ibend(inode);
+       for (bindex = au_ibstart(inode); !err && bindex <= bend; bindex++) {
+               h_inode = au_h_iptr(inode, bindex);
+               if (h_inode) {
+                       AuDebugOn(!S_ISDIR(h_inode->i_mode));
+                       br = au_sbr(sb, bindex);
+                       err = h_permission(h_inode, mask, br->br_mnt,
+                                          br->br_perm);
+               }
+       }
+
+ out:
+       ii_read_unlock(inode);
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct dentry *aufs_lookup(struct inode *dir, struct dentry *dentry,
+                                 struct nameidata *nd)
+{
+       struct dentry *ret, *parent;
+       struct inode *inode, *h_inode;
+       struct mutex *mtx;
+       struct super_block *sb;
+       int err, npositive;
+       aufs_bindex_t bstart;
+
+       /* temporary workaround for a bug in NFSD readdir */
+       if (!au_test_nfsd(current))
+               IMustLock(dir);
+       else
+               WARN_ONCE(!mutex_is_locked(&dir->i_mutex),
+                         "a known problem of NFSD readdir since 2.6.28\n");
+
+       sb = dir->i_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+       err = au_alloc_dinfo(dentry);
+       ret = ERR_PTR(err);
+       if (unlikely(err))
+               goto out;
+
+       parent = dentry->d_parent; /* dir inode is locked */
+       di_read_lock_parent(parent, AuLock_IR);
+       npositive = au_lkup_dentry(dentry, au_dbstart(parent), /*type*/0, nd);
+       di_read_unlock(parent, AuLock_IR);
+       err = npositive;
+       ret = ERR_PTR(err);
+       if (unlikely(err < 0))
+               goto out_unlock;
+
+       inode = NULL;
+       if (npositive) {
+               bstart = au_dbstart(dentry);
+               h_inode = au_h_dptr(dentry, bstart)->d_inode;
+               if (!S_ISDIR(h_inode->i_mode)) {
+                       /*
+                        * stop 'race'-ing between hardlinks under different
+                        * parents.
+                        */
+                       mtx = &au_sbr(sb, bstart)->br_xino.xi_nondir_mtx;
+                       mutex_lock(mtx);
+                       inode = au_new_inode(dentry, /*must_new*/0);
+                       mutex_unlock(mtx);
+               } else
+                       inode = au_new_inode(dentry, /*must_new*/0);
+               ret = (void *)inode;
+       }
+       if (IS_ERR(inode))
+               goto out_unlock;
+
+       ret = d_splice_alias(inode, dentry);
+       if (unlikely(IS_ERR(ret) && inode))
+               ii_write_unlock(inode);
+       au_store_oflag(nd, inode);
+
+ out_unlock:
+       di_write_unlock(dentry);
+ out:
+       si_read_unlock(sb);
+       return ret;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_wr_dir_cpup(struct dentry *dentry, struct dentry *parent,
+                         const unsigned char add_entry, aufs_bindex_t bcpup,
+                         aufs_bindex_t bstart)
+{
+       int err;
+       struct dentry *h_parent;
+       struct inode *h_dir;
+
+       if (add_entry) {
+               au_update_dbstart(dentry);
+               IMustLock(parent->d_inode);
+       } else
+               di_write_lock_parent(parent);
+
+       err = 0;
+       if (!au_h_dptr(parent, bcpup)) {
+               if (bstart < bcpup)
+                       err = au_cpdown_dirs(dentry, bcpup);
+               else
+                       err = au_cpup_dirs(dentry, bcpup);
+       }
+       if (!err && add_entry) {
+               h_parent = au_h_dptr(parent, bcpup);
+               h_dir = h_parent->d_inode;
+               mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_PARENT);
+               err = au_lkup_neg(dentry, bcpup);
+               /* todo: no unlock here */
+               mutex_unlock(&h_dir->i_mutex);
+               if (bstart < bcpup && au_dbstart(dentry) < 0) {
+                       au_set_dbstart(dentry, 0);
+                       au_update_dbrange(dentry, /*do_put_zero*/0);
+               }
+       }
+
+       if (!add_entry)
+               di_write_unlock(parent);
+       if (!err)
+               err = bcpup; /* success */
+
+       return err;
+}
+
+/*
+ * decide the branch and the parent dir where we will create a new entry.
+ * returns new bindex or an error.
+ * copyup the parent dir if needed.
+ */
+int au_wr_dir(struct dentry *dentry, struct dentry *src_dentry,
+             struct au_wr_dir_args *args)
+{
+       int err;
+       aufs_bindex_t bcpup, bstart, src_bstart;
+       const unsigned char add_entry = !!au_ftest_wrdir(args->flags,
+                                                        ADD_ENTRY);
+       struct super_block *sb;
+       struct dentry *parent;
+       struct au_sbinfo *sbinfo;
+
+       sb = dentry->d_sb;
+       sbinfo = au_sbi(sb);
+       parent = dget_parent(dentry);
+       bstart = au_dbstart(dentry);
+       bcpup = bstart;
+       if (args->force_btgt < 0) {
+               if (src_dentry) {
+                       src_bstart = au_dbstart(src_dentry);
+                       if (src_bstart < bstart)
+                               bcpup = src_bstart;
+               } else if (add_entry) {
+                       err = AuWbrCreate(sbinfo, dentry,
+                                         au_ftest_wrdir(args->flags, ISDIR));
+                       bcpup = err;
+               }
+
+               if (bcpup < 0 || au_test_ro(sb, bcpup, dentry->d_inode)) {
+                       if (add_entry)
+                               err = AuWbrCopyup(sbinfo, dentry);
+                       else {
+                               if (!IS_ROOT(dentry)) {
+                                       di_read_lock_parent(parent, !AuLock_IR);
+                                       err = AuWbrCopyup(sbinfo, dentry);
+                                       di_read_unlock(parent, !AuLock_IR);
+                               } else
+                                       err = AuWbrCopyup(sbinfo, dentry);
+                       }
+                       bcpup = err;
+                       if (unlikely(err < 0))
+                               goto out;
+               }
+       } else {
+               bcpup = args->force_btgt;
+               AuDebugOn(au_test_ro(sb, bcpup, dentry->d_inode));
+       }
+       AuDbg("bstart %d, bcpup %d\n", bstart, bcpup);
+       if (bstart < bcpup)
+               au_update_dbrange(dentry, /*do_put_zero*/1);
+
+       err = bcpup;
+       if (bcpup == bstart)
+               goto out; /* success */
+
+       /* copyup the new parent into the branch we process */
+       err = au_wr_dir_cpup(dentry, parent, add_entry, bcpup, bstart);
+
+ out:
+       dput(parent);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct dentry *au_pinned_h_parent(struct au_pin *pin)
+{
+       if (pin && pin->parent)
+               return au_h_dptr(pin->parent, pin->bindex);
+       return NULL;
+}
+
+void au_unpin(struct au_pin *p)
+{
+       if (au_ftest_pin(p->flags, MNT_WRITE))
+               mnt_drop_write(p->h_mnt);
+       if (!p->hdir)
+               return;
+
+       au_hin_imtx_unlock(p->hdir);
+       if (!au_ftest_pin(p->flags, DI_LOCKED))
+               di_read_unlock(p->parent, AuLock_IR);
+       iput(p->hdir->hi_inode);
+       dput(p->parent);
+       p->parent = NULL;
+       p->hdir = NULL;
+       p->h_mnt = NULL;
+}
+
+int au_do_pin(struct au_pin *p)
+{
+       int err;
+       struct super_block *sb;
+       struct dentry *h_dentry, *h_parent;
+       struct au_branch *br;
+       struct inode *h_dir;
+
+       err = 0;
+       sb = p->dentry->d_sb;
+       br = au_sbr(sb, p->bindex);
+       if (IS_ROOT(p->dentry)) {
+               if (au_ftest_pin(p->flags, MNT_WRITE)) {
+                       p->h_mnt = br->br_mnt;
+                       err = mnt_want_write(p->h_mnt);
+                       if (unlikely(err)) {
+                               au_fclr_pin(p->flags, MNT_WRITE);
+                               goto out_err;
+                       }
+               }
+               goto out;
+       }
+
+       h_dentry = NULL;
+       if (p->bindex <= au_dbend(p->dentry))
+               h_dentry = au_h_dptr(p->dentry, p->bindex);
+
+       p->parent = dget_parent(p->dentry);
+       if (!au_ftest_pin(p->flags, DI_LOCKED))
+               di_read_lock(p->parent, AuLock_IR, p->lsc_di);
+
+       h_dir = NULL;
+       h_parent = au_h_dptr(p->parent, p->bindex);
+       p->hdir = au_hi(p->parent->d_inode, p->bindex);
+       if (p->hdir)
+               h_dir = p->hdir->hi_inode;
+
+       /* udba case */
+       if (unlikely(!p->hdir || !h_dir)) {
+               err = au_busy_or_stale();
+               if (!au_ftest_pin(p->flags, DI_LOCKED))
+                       di_read_unlock(p->parent, AuLock_IR);
+               dput(p->parent);
+               p->parent = NULL;
+               goto out_err;
+       }
+
+       au_igrab(h_dir);
+       au_hin_imtx_lock_nested(p->hdir, p->lsc_hi);
+
+       if (h_dentry) {
+               err = au_h_verify(h_dentry, p->udba, h_dir, h_parent, br);
+               if (unlikely(err)) {
+                       au_fclr_pin(p->flags, MNT_WRITE);
+                       goto out_unpin;
+               }
+       }
+
+       if (au_ftest_pin(p->flags, MNT_WRITE)) {
+               p->h_mnt = br->br_mnt;
+               err = mnt_want_write(p->h_mnt);
+               if (unlikely(err)) {
+                       au_fclr_pin(p->flags, MNT_WRITE);
+                       goto out_unpin;
+               }
+       }
+       goto out; /* success */
+
+ out_unpin:
+       au_unpin(p);
+ out_err:
+       AuErr("err %d\n", err);
+       err = au_busy_or_stale();
+ out:
+       return err;
+}
+
+void au_pin_init(struct au_pin *p, struct dentry *dentry,
+                aufs_bindex_t bindex, int lsc_di, int lsc_hi,
+                unsigned int udba, unsigned char flags)
+{
+       p->dentry = dentry;
+       p->udba = udba;
+       p->lsc_di = lsc_di;
+       p->lsc_hi = lsc_hi;
+       p->flags = flags;
+       p->bindex = bindex;
+
+       p->parent = NULL;
+       p->hdir = NULL;
+       p->h_mnt = NULL;
+}
+
+int au_pin(struct au_pin *pin, struct dentry *dentry, aufs_bindex_t bindex,
+          unsigned int udba, unsigned char flags)
+{
+       au_pin_init(pin, dentry, bindex, AuLsc_DI_PARENT, AuLsc_I_PARENT2,
+                   udba, flags);
+       return au_do_pin(pin);
+}
+
+/* ---------------------------------------------------------------------- */
+
+#define AuIcpup_DID_CPUP       1
+#define au_ftest_icpup(flags, name)    ((flags) & AuIcpup_##name)
+#define au_fset_icpup(flags, name)     { (flags) |= AuIcpup_##name; }
+#define au_fclr_icpup(flags, name)     { (flags) &= ~AuIcpup_##name; }
+
+struct au_icpup_args {
+       unsigned char flags;
+       unsigned char pin_flags;
+       aufs_bindex_t btgt;
+       struct au_pin pin;
+       struct path h_path;
+       struct inode *h_inode;
+};
+
+static int au_lock_and_icpup(struct dentry *dentry, struct iattr *ia,
+                            struct au_icpup_args *a)
+{
+       int err;
+       unsigned int udba;
+       loff_t sz;
+       aufs_bindex_t bstart;
+       struct dentry *hi_wh, *parent;
+       struct inode *inode;
+       struct au_wr_dir_args wr_dir_args = {
+               .force_btgt     = -1,
+               .flags          = 0
+       };
+
+       di_write_lock_child(dentry);
+       bstart = au_dbstart(dentry);
+       inode = dentry->d_inode;
+       if (S_ISDIR(inode->i_mode))
+               au_fset_wrdir(wr_dir_args.flags, ISDIR);
+       /* plink or hi_wh() case */
+       if (bstart != au_ibstart(inode))
+               wr_dir_args.force_btgt = au_ibstart(inode);
+       err = au_wr_dir(dentry, /*src_dentry*/NULL, &wr_dir_args);
+       if (unlikely(err < 0))
+               goto out_dentry;
+       a->btgt = err;
+       if (err != bstart)
+               au_fset_icpup(a->flags, DID_CPUP);
+
+       err = 0;
+       a->pin_flags = AuPin_MNT_WRITE;
+       parent = NULL;
+       if (!IS_ROOT(dentry)) {
+               au_fset_pin(a->pin_flags, DI_LOCKED);
+               parent = dget_parent(dentry);
+               di_write_lock_parent(parent);
+       }
+
+       udba = au_opt_udba(dentry->d_sb);
+       if (d_unhashed(dentry) || (ia->ia_valid & ATTR_FILE))
+               udba = AuOpt_UDBA_NONE;
+       err = au_pin(&a->pin, dentry, a->btgt, udba, a->pin_flags);
+       if (unlikely(err)) {
+               if (parent) {
+                       di_write_unlock(parent);
+                       dput(parent);
+               }
+               goto out_dentry;
+       }
+       a->h_path.dentry = au_h_dptr(dentry, bstart);
+       a->h_inode = a->h_path.dentry->d_inode;
+       mutex_lock_nested(&a->h_inode->i_mutex, AuLsc_I_CHILD);
+       sz = -1;
+       if ((ia->ia_valid & ATTR_SIZE) && ia->ia_size < i_size_read(a->h_inode))
+               sz = ia->ia_size;
+
+       hi_wh = NULL;
+       if (au_ftest_icpup(a->flags, DID_CPUP) && d_unhashed(dentry)) {
+               hi_wh = au_hi_wh(inode, a->btgt);
+               if (!hi_wh) {
+                       err = au_sio_cpup_wh(dentry, a->btgt, sz, /*file*/NULL);
+                       if (unlikely(err))
+                               goto out_unlock;
+                       hi_wh = au_hi_wh(inode, a->btgt);
+                       /* todo: revalidate hi_wh? */
+               }
+       }
+
+       if (parent) {
+               au_pin_set_parent_lflag(&a->pin, /*lflag*/0);
+               di_downgrade_lock(parent, AuLock_IR);
+               dput(parent);
+       }
+       if (!au_ftest_icpup(a->flags, DID_CPUP))
+               goto out; /* success */
+
+       if (!d_unhashed(dentry)) {
+               err = au_sio_cpup_simple(dentry, a->btgt, sz, AuCpup_DTIME);
+               if (!err)
+                       a->h_path.dentry = au_h_dptr(dentry, a->btgt);
+       } else if (!hi_wh)
+               a->h_path.dentry = au_h_dptr(dentry, a->btgt);
+       else
+               a->h_path.dentry = hi_wh; /* do not dget here */
+
+ out_unlock:
+       mutex_unlock(&a->h_inode->i_mutex);
+       a->h_inode = a->h_path.dentry->d_inode;
+       if (!err) {
+               mutex_lock_nested(&a->h_inode->i_mutex, AuLsc_I_CHILD);
+               goto out; /* success */
+       }
+
+       au_unpin(&a->pin);
+
+ out_dentry:
+       di_write_unlock(dentry);
+ out:
+       return err;
+}
+
+static int aufs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+       int err;
+       struct inode *inode;
+       struct super_block *sb;
+       struct file *file;
+       struct au_icpup_args *a;
+
+       err = -ENOMEM;
+       a = kzalloc(sizeof(*a), GFP_NOFS);
+       if (unlikely(!a))
+               goto out;
+
+       inode = dentry->d_inode;
+       IMustLock(inode);
+       sb = dentry->d_sb;
+       si_read_lock(sb, AuLock_FLUSH);
+
+       file = NULL;
+       if (ia->ia_valid & ATTR_FILE) {
+               /* currently ftruncate(2) only */
+               file = ia->ia_file;
+               fi_write_lock(file);
+               ia->ia_file = au_h_fptr(file, au_fbstart(file));
+       }
+
+       if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
+               ia->ia_valid &= ~ATTR_MODE;
+
+       err = au_lock_and_icpup(dentry, ia, a);
+       if (unlikely(err < 0))
+               goto out_si;
+       if (au_ftest_icpup(a->flags, DID_CPUP)) {
+               ia->ia_file = NULL;
+               ia->ia_valid &= ~ATTR_FILE;
+       }
+
+       a->h_path.mnt = au_sbr_mnt(sb, a->btgt);
+       if (ia->ia_valid & ATTR_SIZE) {
+               struct file *f;
+
+               if (ia->ia_size < i_size_read(inode)) {
+                       /* unmap only */
+                       err = vmtruncate(inode, ia->ia_size);
+                       if (unlikely(err))
+                               goto out_unlock;
+               }
+
+               f = NULL;
+               if (ia->ia_valid & ATTR_FILE)
+                       f = ia->ia_file;
+               mutex_unlock(&a->h_inode->i_mutex);
+               err = vfsub_trunc(&a->h_path, ia->ia_size, ia->ia_valid, f);
+               mutex_lock_nested(&a->h_inode->i_mutex, AuLsc_I_CHILD);
+       } else
+               err = vfsub_notify_change(&a->h_path, ia);
+       if (!err)
+               au_cpup_attr_changeable(inode);
+
+ out_unlock:
+       mutex_unlock(&a->h_inode->i_mutex);
+       au_unpin(&a->pin);
+       di_write_unlock(dentry);
+ out_si:
+       if (file) {
+               fi_write_unlock(file);
+               ia->ia_file = file;
+               ia->ia_valid |= ATTR_FILE;
+       }
+       si_read_unlock(sb);
+       kfree(a);
+ out:
+       return err;
+}
+
+static int au_getattr_lock_reval(struct dentry *dentry, unsigned int sigen)
+{
+       int err;
+       struct inode *inode;
+       struct dentry *parent;
+
+       err = 0;
+       inode = dentry->d_inode;
+       di_write_lock_child(dentry);
+       if (au_digen(dentry) != sigen || au_iigen(inode) != sigen) {
+               parent = dget_parent(dentry);
+               di_read_lock_parent(parent, AuLock_IR);
+               /* returns a number of positive dentries */
+               err = au_refresh_hdentry(dentry, inode->i_mode & S_IFMT);
+               if (err > 0)
+                       err = au_refresh_hinode(inode, dentry);
+               di_read_unlock(parent, AuLock_IR);
+               dput(parent);
+               if (unlikely(!err))
+                       err = -EIO;
+       }
+       di_downgrade_lock(dentry, AuLock_IR);
+
+       return err;
+}
+
+static void au_refresh_iattr(struct inode *inode, struct kstat *st,
+                            unsigned int nlink)
+{
+       inode->i_mode = st->mode;
+       inode->i_uid = st->uid;
+       inode->i_gid = st->gid;
+       inode->i_atime = st->atime;
+       inode->i_mtime = st->mtime;
+       inode->i_ctime = st->ctime;
+
+       au_cpup_attr_nlink(inode, /*force*/0);
+       if (S_ISDIR(inode->i_mode)) {
+               inode->i_nlink -= nlink;
+               inode->i_nlink += st->nlink;
+       }
+
+       spin_lock(&inode->i_lock);
+       inode->i_blocks = st->blocks;
+       i_size_write(inode, st->size);
+       spin_unlock(&inode->i_lock);
+}
+
+static int aufs_getattr(struct vfsmount *mnt __maybe_unused,
+                       struct dentry *dentry, struct kstat *st)
+{
+       int err;
+       unsigned int mnt_flags;
+       aufs_bindex_t bindex;
+       unsigned char udba_none, positive, did_lock;
+       struct super_block *sb, *h_sb;
+       struct inode *inode;
+       struct vfsmount *h_mnt;
+       struct dentry *h_dentry;
+
+       err = 0;
+       did_lock = 0;
+       sb = dentry->d_sb;
+       inode = dentry->d_inode;
+       si_read_lock(sb, AuLock_FLUSH);
+       if (IS_ROOT(dentry)) {
+               /* lock free root dinfo */
+               h_dentry = dget(au_di(dentry)->di_hdentry->hd_dentry);
+               h_mnt = au_sbr_mnt(sb, 0);
+               goto getattr;
+       }
+
+       did_lock = 1;
+       mnt_flags = au_mntflags(sb);
+       udba_none = !!au_opt_test(mnt_flags, UDBA_NONE);
+
+       /* support fstat(2) */
+       if (!d_unhashed(dentry) && !udba_none) {
+               unsigned int sigen = au_sigen(sb);
+               if (au_digen(dentry) == sigen && au_iigen(inode) == sigen)
+                       di_read_lock_child(dentry, AuLock_IR);
+               else {
+                       err = au_getattr_lock_reval(dentry, sigen);
+                       if (unlikely(err))
+                               goto out;
+               }
+       } else
+               di_read_lock_child(dentry, AuLock_IR);
+
+       bindex = au_ibstart(inode);
+       h_mnt = au_sbr_mnt(sb, bindex);
+       h_sb = h_mnt->mnt_sb;
+       if (!au_test_fs_bad_iattr(h_sb) && udba_none)
+               goto out_fill; /* success */
+
+       if (au_dbstart(dentry) == bindex)
+               h_dentry = dget(au_h_dptr(dentry, bindex));
+       else if (au_opt_test(mnt_flags, PLINK) && au_plink_test(inode)) {
+               h_dentry = au_plink_lkup(inode, bindex);
+               if (IS_ERR(h_dentry))
+                       goto out_fill; /* pretending success */
+       } else
+               /* illegally overlapped or something */
+               goto out_fill; /* pretending success */
+
+ getattr:
+       positive = !!h_dentry->d_inode;
+       if (positive)
+               err = vfs_getattr(h_mnt, h_dentry, st);
+       dput(h_dentry);
+       if (!err) {
+               if (positive)
+                       au_refresh_iattr(inode, st, h_dentry->d_inode->i_nlink);
+               goto out_fill; /* success */
+       }
+       goto out;
+
+ out_fill:
+       generic_fillattr(inode, st);
+ out:
+       if (did_lock)
+               di_read_unlock(dentry, AuLock_IR);
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int h_readlink(struct dentry *dentry, int bindex, char __user *buf,
+                     int bufsiz)
+{
+       int err;
+       struct super_block *sb;
+       struct dentry *h_dentry;
+
+       err = -EINVAL;
+       h_dentry = au_h_dptr(dentry, bindex);
+       if (unlikely(/* !h_dentry
+                    || !h_dentry->d_inode
+                    || !h_dentry->d_inode->i_op
+                    || */ !h_dentry->d_inode->i_op->readlink))
+               goto out;
+
+       err = security_inode_readlink(h_dentry);
+       if (unlikely(err))
+               goto out;
+
+       sb = dentry->d_sb;
+       if (!au_test_ro(sb, bindex, dentry->d_inode)) {
+               vfsub_touch_atime(au_sbr_mnt(sb, bindex), h_dentry);
+               fsstack_copy_attr_atime(dentry->d_inode, h_dentry->d_inode);
+       }
+       err = h_dentry->d_inode->i_op->readlink(h_dentry, buf, bufsiz);
+
+ out:
+       return err;
+}
+
+static int aufs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
+{
+       int err;
+
+       aufs_read_lock(dentry, AuLock_IR);
+       err = h_readlink(dentry, au_dbstart(dentry), buf, bufsiz);
+       aufs_read_unlock(dentry, AuLock_IR);
+
+       return err;
+}
+
+static void *aufs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+       int err;
+       char *buf;
+       mm_segment_t old_fs;
+
+       err = -ENOMEM;
+       buf = __getname();
+       if (unlikely(!buf))
+               goto out;
+
+       aufs_read_lock(dentry, AuLock_IR);
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+       err = h_readlink(dentry, au_dbstart(dentry), (char __user *)buf,
+                        PATH_MAX);
+       set_fs(old_fs);
+       aufs_read_unlock(dentry, AuLock_IR);
+
+       if (err >= 0) {
+               buf[err] = 0;
+               /* will be freed by put_link */
+               nd_set_link(nd, buf);
+               return NULL; /* success */
+       }
+       __putname(buf);
+
+ out:
+       path_put(&nd->path);
+       AuTraceErr(err);
+       return ERR_PTR(err);
+}
+
+static void aufs_put_link(struct dentry *dentry __maybe_unused,
+                         struct nameidata *nd, void *cookie __maybe_unused)
+{
+       __putname(nd_get_link(nd));
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void aufs_truncate_range(struct inode *inode __maybe_unused,
+                               loff_t start __maybe_unused,
+                               loff_t end __maybe_unused)
+{
+       AuUnsupport();
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct inode_operations aufs_symlink_iop = {
+       .permission     = aufs_permission,
+       .setattr        = aufs_setattr,
+       .getattr        = aufs_getattr,
+       .readlink       = aufs_readlink,
+       .follow_link    = aufs_follow_link,
+       .put_link       = aufs_put_link
+};
+
+struct inode_operations aufs_dir_iop = {
+       .create         = aufs_create,
+       .lookup         = aufs_lookup,
+       .link           = aufs_link,
+       .unlink         = aufs_unlink,
+       .symlink        = aufs_symlink,
+       .mkdir          = aufs_mkdir,
+       .rmdir          = aufs_rmdir,
+       .mknod          = aufs_mknod,
+       .rename         = aufs_rename,
+
+       .permission     = aufs_permission,
+       .setattr        = aufs_setattr,
+       .getattr        = aufs_getattr
+};
+
+struct inode_operations aufs_iop = {
+       .permission     = aufs_permission,
+       .setattr        = aufs_setattr,
+       .getattr        = aufs_getattr,
+       .truncate_range = aufs_truncate_range
+};
diff --git a/fs/aufs/i_op_add.c b/fs/aufs/i_op_add.c
new file mode 100644
index 0000000..516120d
--- /dev/null
+++ b/fs/aufs/i_op_add.c
@@ -0,0 +1,625 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode operations (add entry)
+ */
+
+#include "aufs.h"
+
+/*
+ * final procedure of adding a new entry, except link(2).
+ * remove whiteout, instantiate, copyup the parent dir's times and size
+ * and update version.
+ * if it failed, re-create the removed whiteout.
+ */
+static int epilog(struct inode *dir, aufs_bindex_t bindex,
+                 struct dentry *wh_dentry, struct dentry *dentry)
+{
+       int err, rerr;
+       aufs_bindex_t bwh;
+       struct path h_path;
+       struct inode *inode, *h_dir;
+       struct dentry *wh;
+
+       bwh = -1;
+       if (wh_dentry) {
+               h_dir = wh_dentry->d_parent->d_inode; /* dir inode is locked */
+               IMustLock(h_dir);
+               AuDebugOn(au_h_iptr(dir, bindex) != h_dir);
+               bwh = au_dbwh(dentry);
+               h_path.dentry = wh_dentry;
+               h_path.mnt = au_sbr_mnt(dir->i_sb, bindex);
+               err = au_wh_unlink_dentry(au_h_iptr(dir, bindex), &h_path,
+                                         dentry);
+               if (unlikely(err))
+                       goto out;
+       }
+
+       inode = au_new_inode(dentry, /*must_new*/1);
+       if (!IS_ERR(inode)) {
+               d_instantiate(dentry, inode);
+               dir = dentry->d_parent->d_inode; /* dir inode is locked */
+               IMustLock(dir);
+               if (au_ibstart(dir) == au_dbstart(dentry))
+                       au_cpup_attr_timesizes(dir);
+               dir->i_version++;
+               return 0; /* success */
+       }
+
+       err = PTR_ERR(inode);
+       if (!wh_dentry)
+               goto out;
+
+       /* revert */
+       /* dir inode is locked */
+       wh = au_wh_create(dentry, bwh, wh_dentry->d_parent);
+       rerr = PTR_ERR(wh);
+       if (IS_ERR(wh)) {
+               AuIOErr("%.*s reverting whiteout failed(%d, %d)\n",
+                       AuDLNPair(dentry), err, rerr);
+               err = -EIO;
+       } else
+               dput(wh);
+
+ out:
+       return err;
+}
+
+/*
+ * simple tests for the adding inode operations.
+ * following the checks in vfs, plus the parent-child relationship.
+ */
+int au_may_add(struct dentry *dentry, aufs_bindex_t bindex,
+              struct dentry *h_parent, int isdir)
+{
+       int err;
+       umode_t h_mode;
+       struct dentry *h_dentry;
+       struct inode *h_inode;
+
+       h_dentry = au_h_dptr(dentry, bindex);
+       h_inode = h_dentry->d_inode;
+       if (!dentry->d_inode) {
+               err = -EEXIST;
+               if (unlikely(h_inode))
+                       goto out;
+       } else {
+               /* rename(2) case */
+               err = -EIO;
+               if (unlikely(!h_inode || !h_inode->i_nlink))
+                       goto out;
+
+               h_mode = h_inode->i_mode;
+               if (!isdir) {
+                       err = -EISDIR;
+                       if (unlikely(S_ISDIR(h_mode)))
+                               goto out;
+               } else if (unlikely(!S_ISDIR(h_mode))) {
+                       err = -ENOTDIR;
+                       goto out;
+               }
+       }
+
+       err = -EIO;
+       /* expected parent dir is locked */
+       if (unlikely(h_parent != h_dentry->d_parent))
+               goto out;
+       err = 0;
+
+ out:
+       return err;
+}
+
+/*
+ * initial procedure of adding a new entry.
+ * prepare writable branch and the parent dir, lock it,
+ * and lookup whiteout for the new entry.
+ */
+static struct dentry*
+lock_hdir_lkup_wh(struct dentry *dentry, struct au_dtime *dt,
+                 struct dentry *src_dentry, struct au_pin *pin,
+                 struct au_wr_dir_args *wr_dir_args)
+{
+       struct dentry *wh_dentry, *h_parent;
+       struct super_block *sb;
+       struct au_branch *br;
+       int err;
+       unsigned int udba;
+       aufs_bindex_t bcpup;
+
+       err = au_wr_dir(dentry, src_dentry, wr_dir_args);
+       bcpup = err;
+       wh_dentry = ERR_PTR(err);
+       if (unlikely(err < 0))
+               goto out;
+
+       sb = dentry->d_sb;
+       udba = au_opt_udba(sb);
+       err = au_pin(pin, dentry, bcpup, udba,
+                    AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+       wh_dentry = ERR_PTR(err);
+       if (unlikely(err))
+               goto out;
+
+       h_parent = au_pinned_h_parent(pin);
+       if (udba != AuOpt_UDBA_NONE
+           && au_dbstart(dentry) == bcpup) {
+               err = au_may_add(dentry, bcpup, h_parent,
+                                au_ftest_wrdir(wr_dir_args->flags, ISDIR));
+               wh_dentry = ERR_PTR(err);
+               if (unlikely(err))
+                       goto out_unpin;
+       }
+
+       br = au_sbr(sb, bcpup);
+       if (dt) {
+               struct path tmp = {
+                       .dentry = h_parent,
+                       .mnt    = br->br_mnt
+               };
+               au_dtime_store(dt, au_pinned_parent(pin), &tmp);
+       }
+
+       wh_dentry = NULL;
+       if (bcpup != au_dbwh(dentry))
+               goto out; /* success */
+
+       wh_dentry = au_wh_lkup(h_parent, &dentry->d_name, br);
+
+ out_unpin:
+       if (IS_ERR(wh_dentry))
+               au_unpin(pin);
+ out:
+       return wh_dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+enum { Mknod, Symlink, Creat };
+struct simple_arg {
+       int type;
+       union {
+               struct {
+                       int mode;
+                       struct nameidata *nd;
+               } c;
+               struct {
+                       const char *symname;
+               } s;
+               struct {
+                       int mode;
+                       dev_t dev;
+               } m;
+       } u;
+};
+
+static int add_simple(struct inode *dir, struct dentry *dentry,
+                     struct simple_arg *arg)
+{
+       int err;
+       aufs_bindex_t bstart;
+       unsigned char created;
+       struct au_dtime dt;
+       struct au_pin pin;
+       struct path h_path;
+       struct dentry *wh_dentry, *parent;
+       struct inode *h_dir;
+       struct au_wr_dir_args wr_dir_args = {
+               .force_btgt     = -1,
+               .flags          = AuWrDir_ADD_ENTRY
+       };
+
+       IMustLock(dir);
+
+       parent = dentry->d_parent; /* dir inode is locked */
+       aufs_read_lock(dentry, AuLock_DW);
+       di_write_lock_parent(parent);
+       wh_dentry = lock_hdir_lkup_wh(dentry, &dt, /*src_dentry*/NULL, &pin,
+                                     &wr_dir_args);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out;
+
+       bstart = au_dbstart(dentry);
+       h_path.dentry = au_h_dptr(dentry, bstart);
+       h_path.mnt = au_sbr_mnt(dentry->d_sb, bstart);
+       h_dir = au_pinned_h_dir(&pin);
+       switch (arg->type) {
+       case Creat:
+               err = vfsub_create(h_dir, &h_path, arg->u.c.mode);
+               break;
+       case Symlink:
+               err = vfsub_symlink(h_dir, &h_path, arg->u.s.symname);
+               break;
+       case Mknod:
+               err = vfsub_mknod(h_dir, &h_path, arg->u.m.mode, arg->u.m.dev);
+               break;
+       default:
+               BUG();
+       }
+       created = !err;
+       if (!err)
+               err = epilog(dir, bstart, wh_dentry, dentry);
+
+       /* revert */
+       if (unlikely(created && err && h_path.dentry->d_inode)) {
+               int rerr;
+               rerr = vfsub_unlink(h_dir, &h_path, /*force*/0);
+               if (rerr) {
+                       AuIOErr("%.*s revert failure(%d, %d)\n",
+                               AuDLNPair(dentry), err, rerr);
+                       err = -EIO;
+               }
+               au_dtime_revert(&dt);
+               d_drop(dentry);
+       }
+
+       au_unpin(&pin);
+       dput(wh_dentry);
+
+ out:
+       if (unlikely(err)) {
+               au_update_dbstart(dentry);
+               d_drop(dentry);
+       }
+       di_write_unlock(parent);
+       aufs_read_unlock(dentry, AuLock_DW);
+       return err;
+}
+
+int aufs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+{
+       struct simple_arg arg = {
+               .type = Mknod,
+               .u.m = {
+                       .mode   = mode,
+                       .dev    = dev
+               }
+       };
+       return add_simple(dir, dentry, &arg);
+}
+
+int aufs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+       struct simple_arg arg = {
+               .type = Symlink,
+               .u.s.symname = symname
+       };
+       return add_simple(dir, dentry, &arg);
+}
+
+int aufs_create(struct inode *dir, struct dentry *dentry, int mode,
+               struct nameidata *nd)
+{
+       struct simple_arg arg = {
+               .type = Creat,
+               .u.c = {
+                       .mode   = mode,
+                       .nd     = nd
+               }
+       };
+       return add_simple(dir, dentry, &arg);
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct au_link_args {
+       aufs_bindex_t bdst, bsrc;
+       struct au_pin pin;
+       struct path h_path;
+       struct dentry *src_parent, *parent;
+};
+
+static int au_cpup_before_link(struct dentry *src_dentry,
+                              struct au_link_args *a)
+{
+       int err;
+       struct dentry *h_src_dentry;
+       struct mutex *h_mtx;
+
+       di_read_lock_parent(a->src_parent, AuLock_IR);
+       err = au_test_and_cpup_dirs(src_dentry, a->bdst);
+       if (unlikely(err))
+               goto out;
+
+       h_src_dentry = au_h_dptr(src_dentry, a->bsrc);
+       h_mtx = &h_src_dentry->d_inode->i_mutex;
+       err = au_pin(&a->pin, src_dentry, a->bdst,
+                    au_opt_udba(src_dentry->d_sb),
+                    AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+       if (unlikely(err))
+               goto out;
+       mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+       err = au_sio_cpup_simple(src_dentry, a->bdst, -1,
+                                AuCpup_DTIME /* | AuCpup_KEEPLINO */);
+       mutex_unlock(h_mtx);
+       au_unpin(&a->pin);
+
+ out:
+       di_read_unlock(a->src_parent, AuLock_IR);
+       return err;
+}
+
+static int au_cpup_or_link(struct dentry *src_dentry, struct au_link_args *a)
+{
+       int err;
+       unsigned char plink;
+       struct inode *h_inode, *inode;
+       struct dentry *h_src_dentry;
+       struct super_block *sb;
+
+       plink = 0;
+       h_inode = NULL;
+       sb = src_dentry->d_sb;
+       inode = src_dentry->d_inode;
+       if (au_ibstart(inode) <= a->bdst)
+               h_inode = au_h_iptr(inode, a->bdst);
+       if (!h_inode || !h_inode->i_nlink) {
+               /* copyup src_dentry as the name of dentry. */
+               au_set_dbstart(src_dentry, a->bdst);
+               au_set_h_dptr(src_dentry, a->bdst, dget(a->h_path.dentry));
+               h_inode = au_h_dptr(src_dentry, a->bsrc)->d_inode;
+               mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+               err = au_sio_cpup_single(src_dentry, a->bdst, a->bsrc, -1,
+                                        AuCpup_KEEPLINO, a->parent);
+               mutex_unlock(&h_inode->i_mutex);
+               au_set_h_dptr(src_dentry, a->bdst, NULL);
+               au_set_dbstart(src_dentry, a->bsrc);
+       } else {
+               /* the inode of src_dentry already exists on a.bdst branch */
+               h_src_dentry = d_find_alias(h_inode);
+               if (!h_src_dentry && au_plink_test(inode)) {
+                       plink = 1;
+                       h_src_dentry = au_plink_lkup(inode, a->bdst);
+                       err = PTR_ERR(h_src_dentry);
+                       if (IS_ERR(h_src_dentry))
+                               goto out;
+
+                       if (unlikely(!h_src_dentry->d_inode)) {
+                               dput(h_src_dentry);
+                               h_src_dentry = NULL;
+                       }
+
+               }
+               if (h_src_dentry) {
+                       err = vfsub_link(h_src_dentry, au_pinned_h_dir(&a->pin),
+                                        &a->h_path);
+                       dput(h_src_dentry);
+               } else {
+                       AuIOErr("no dentry found for hi%lu on b%d\n",
+                               h_inode->i_ino, a->bdst);
+                       err = -EIO;
+               }
+       }
+
+       if (!err && !plink)
+               au_plink_append(inode, a->bdst, a->h_path.dentry);
+
+out:
+       return err;
+}
+
+int aufs_link(struct dentry *src_dentry, struct inode *dir,
+             struct dentry *dentry)
+{
+       int err, rerr;
+       struct au_dtime dt;
+       struct au_link_args *a;
+       struct dentry *wh_dentry, *h_src_dentry;
+       struct inode *inode;
+       struct super_block *sb;
+       struct au_wr_dir_args wr_dir_args = {
+               /* .force_btgt  = -1, */
+               .flags          = AuWrDir_ADD_ENTRY
+       };
+
+       IMustLock(dir);
+       inode = src_dentry->d_inode;
+       IMustLock(inode);
+
+       err = -ENOMEM;
+       a = kzalloc(sizeof(*a), GFP_NOFS);
+       if (unlikely(!a))
+               goto out;
+
+       a->parent = dentry->d_parent; /* dir inode is locked */
+       aufs_read_and_write_lock2(dentry, src_dentry, /*AuLock_FLUSH*/0);
+       a->src_parent = dget_parent(src_dentry);
+       wr_dir_args.force_btgt = au_dbstart(src_dentry);
+
+       di_write_lock_parent(a->parent);
+       wr_dir_args.force_btgt = au_wbr(dentry, wr_dir_args.force_btgt);
+       wh_dentry = lock_hdir_lkup_wh(dentry, &dt, src_dentry, &a->pin,
+                                     &wr_dir_args);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out_unlock;
+
+       err = 0;
+       sb = dentry->d_sb;
+       a->bdst = au_dbstart(dentry);
+       a->h_path.dentry = au_h_dptr(dentry, a->bdst);
+       a->h_path.mnt = au_sbr_mnt(sb, a->bdst);
+       a->bsrc = au_dbstart(src_dentry);
+       if (au_opt_test(au_mntflags(sb), PLINK)) {
+               if (a->bdst < a->bsrc
+                   /* && h_src_dentry->d_sb != a->h_path.dentry->d_sb */)
+                       err = au_cpup_or_link(src_dentry, a);
+               else {
+                       h_src_dentry = au_h_dptr(src_dentry, a->bdst);
+                       err = vfsub_link(h_src_dentry, au_pinned_h_dir(&a->pin),
+                                        &a->h_path);
+               }
+       } else {
+               /*
+                * copyup src_dentry to the branch we process,
+                * and then link(2) to it.
+                */
+               if (a->bdst < a->bsrc
+                   /* && h_src_dentry->d_sb != a->h_path.dentry->d_sb */) {
+                       au_unpin(&a->pin);
+                       di_write_unlock(a->parent);
+                       err = au_cpup_before_link(src_dentry, a);
+                       if (!err) {
+                               di_write_lock_parent(a->parent);
+                               err = au_pin(&a->pin, dentry, a->bdst,
+                                            au_opt_udba(sb),
+                                            AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+                               if (unlikely(err))
+                                       goto out_wh;
+                       }
+               }
+               if (!err) {
+                       h_src_dentry = au_h_dptr(src_dentry, a->bdst);
+                       err = vfsub_link(h_src_dentry, au_pinned_h_dir(&a->pin),
+                                        &a->h_path);
+               }
+       }
+       if (unlikely(err))
+               goto out_unpin;
+
+       if (wh_dentry) {
+               a->h_path.dentry = wh_dentry;
+               err = au_wh_unlink_dentry(au_pinned_h_dir(&a->pin), &a->h_path,
+                                         dentry);
+               if (unlikely(err))
+                       goto out_revert;
+       }
+
+       dir->i_version++;
+       if (au_ibstart(dir) == au_dbstart(dentry))
+               au_cpup_attr_timesizes(dir);
+       inc_nlink(inode);
+       inode->i_ctime = dir->i_ctime;
+       if (!d_unhashed(a->h_path.dentry))
+               d_instantiate(dentry, au_igrab(inode));
+       else
+               /* some filesystem calls d_drop() */
+               d_drop(dentry);
+       goto out_unpin; /* success */
+
+ out_revert:
+       rerr = vfsub_unlink(au_pinned_h_dir(&a->pin), &a->h_path, /*force*/0);
+       if (!rerr)
+               goto out_dt;
+       AuIOErr("%.*s reverting failed(%d, %d)\n",
+               AuDLNPair(dentry), err, rerr);
+       err = -EIO;
+ out_dt:
+       d_drop(dentry);
+       au_dtime_revert(&dt);
+ out_unpin:
+       au_unpin(&a->pin);
+ out_wh:
+       dput(wh_dentry);
+ out_unlock:
+       if (unlikely(err)) {
+               au_update_dbstart(dentry);
+               d_drop(dentry);
+       }
+       di_write_unlock(a->parent);
+       dput(a->src_parent);
+       aufs_read_and_write_unlock2(dentry, src_dentry);
+       kfree(a);
+ out:
+       return err;
+}
+
+int aufs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+       int err, rerr;
+       aufs_bindex_t bindex;
+       unsigned char diropq;
+       struct au_pin pin;
+       struct path h_path;
+       struct dentry *wh_dentry, *parent, *opq_dentry;
+       struct mutex *h_mtx;
+       struct super_block *sb;
+       struct au_dtime dt;
+       struct au_wr_dir_args wr_dir_args = {
+               .force_btgt     = -1,
+               .flags          = AuWrDir_ADD_ENTRY | AuWrDir_ISDIR
+       };
+
+       IMustLock(dir);
+
+       aufs_read_lock(dentry, AuLock_DW);
+       parent = dentry->d_parent; /* dir inode is locked */
+       di_write_lock_parent(parent);
+       wh_dentry = lock_hdir_lkup_wh(dentry, &dt, /*src_dentry*/NULL, &pin,
+                                     &wr_dir_args);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out;
+
+       sb = dentry->d_sb;
+       bindex = au_dbstart(dentry);
+       h_path.dentry = au_h_dptr(dentry, bindex);
+       h_path.mnt = au_sbr_mnt(sb, bindex);
+       err = vfsub_mkdir(au_pinned_h_dir(&pin), &h_path, mode);
+       if (unlikely(err))
+               goto out_unlock;
+
+       /* make the dir opaque */
+       diropq = 0;
+       h_mtx = &h_path.dentry->d_inode->i_mutex;
+       if (wh_dentry
+           || au_opt_test(au_mntflags(sb), ALWAYS_DIROPQ)) {
+               mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+               opq_dentry = au_diropq_create(dentry, bindex);
+               mutex_unlock(h_mtx);
+               err = PTR_ERR(opq_dentry);
+               if (IS_ERR(opq_dentry))
+                       goto out_dir;
+               dput(opq_dentry);
+               diropq = 1;
+       }
+
+       err = epilog(dir, bindex, wh_dentry, dentry);
+       if (!err) {
+               inc_nlink(dir);
+               goto out_unlock; /* success */
+       }
+
+       /* revert */
+       if (diropq) {
+               AuLabel(revert opq);
+               mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+               rerr = au_diropq_remove(dentry, bindex);
+               mutex_unlock(h_mtx);
+               if (rerr) {
+                       AuIOErr("%.*s reverting diropq failed(%d, %d)\n",
+                               AuDLNPair(dentry), err, rerr);
+                       err = -EIO;
+               }
+       }
+
+ out_dir:
+       AuLabel(revert dir);
+       rerr = vfsub_rmdir(au_pinned_h_dir(&pin), &h_path);
+       if (rerr) {
+               AuIOErr("%.*s reverting dir failed(%d, %d)\n",
+                       AuDLNPair(dentry), err, rerr);
+               err = -EIO;
+       }
+       d_drop(dentry);
+       au_dtime_revert(&dt);
+ out_unlock:
+       au_unpin(&pin);
+       dput(wh_dentry);
+ out:
+       if (unlikely(err)) {
+               au_update_dbstart(dentry);
+               d_drop(dentry);
+       }
+       di_write_unlock(parent);
+       aufs_read_unlock(dentry, AuLock_DW);
+       return err;
+}
diff --git a/fs/aufs/i_op_del.c b/fs/aufs/i_op_del.c
new file mode 100644
index 0000000..a9756ae
--- /dev/null
+++ b/fs/aufs/i_op_del.c
@@ -0,0 +1,463 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode operations (del entry)
+ */
+
+#include "aufs.h"
+
+/*
+ * decide if a new whiteout for @dentry is necessary or not.
+ * when it is necessary, prepare the parent dir for the upper branch whose
+ * branch index is @bcpup for creation. the actual creation of the whiteout will
+ * be done by caller.
+ * return value:
+ * 0: wh is unnecessary
+ * plus: wh is necessary
+ * minus: error
+ */
+int au_wr_dir_need_wh(struct dentry *dentry, int isdir, aufs_bindex_t *bcpup)
+{
+       int need_wh, err;
+       aufs_bindex_t bstart;
+       struct super_block *sb;
+
+       sb = dentry->d_sb;
+       bstart = au_dbstart(dentry);
+       if (*bcpup < 0) {
+               *bcpup = bstart;
+               if (au_test_ro(sb, bstart, dentry->d_inode)) {
+                       err = AuWbrCopyup(au_sbi(sb), dentry);
+                       *bcpup = err;
+                       if (unlikely(err < 0))
+                               goto out;
+               }
+       } else
+               AuDebugOn(bstart < *bcpup
+                         || au_test_ro(sb, *bcpup, dentry->d_inode));
+       AuDbg("bcpup %d, bstart %d\n", *bcpup, bstart);
+
+       if (*bcpup != bstart) {
+               err = au_cpup_dirs(dentry, *bcpup);
+               if (unlikely(err))
+                       goto out;
+               need_wh = 1;
+       } else {
+               aufs_bindex_t old_bend, new_bend, bdiropq = -1;
+
+               old_bend = au_dbend(dentry);
+               if (isdir) {
+                       bdiropq = au_dbdiropq(dentry);
+                       au_set_dbdiropq(dentry, -1);
+               }
+               need_wh = au_lkup_dentry(dentry, bstart + 1, /*type*/0,
+                                        /*nd*/NULL);
+               err = need_wh;
+               if (isdir)
+                       au_set_dbdiropq(dentry, bdiropq);
+               if (unlikely(err < 0))
+                       goto out;
+               new_bend = au_dbend(dentry);
+               if (!need_wh && old_bend != new_bend) {
+                       au_set_h_dptr(dentry, new_bend, NULL);
+                       au_set_dbend(dentry, old_bend);
+               }
+       }
+       AuDbg("need_wh %d\n", need_wh);
+       err = need_wh;
+
+ out:
+       return err;
+}
+
+/*
+ * simple tests for the del-entry operations.
+ * following the checks in vfs, plus the parent-child relationship.
+ */
+int au_may_del(struct dentry *dentry, aufs_bindex_t bindex,
+              struct dentry *h_parent, int isdir)
+{
+       int err;
+       umode_t h_mode;
+       struct dentry *h_dentry, *h_latest;
+       struct inode *h_inode;
+
+       h_dentry = au_h_dptr(dentry, bindex);
+       h_inode = h_dentry->d_inode;
+       if (dentry->d_inode) {
+               err = -ENOENT;
+               if (unlikely(!h_inode || !h_inode->i_nlink))
+                       goto out;
+
+               h_mode = h_inode->i_mode;
+               if (!isdir) {
+                       err = -EISDIR;
+                       if (unlikely(S_ISDIR(h_mode)))
+                               goto out;
+               } else if (unlikely(!S_ISDIR(h_mode))) {
+                       err = -ENOTDIR;
+                       goto out;
+               }
+       } else {
+               /* rename(2) case */
+               err = -EIO;
+               if (unlikely(h_inode))
+                       goto out;
+       }
+
+       err = -ENOENT;
+       /* expected parent dir is locked */
+       if (unlikely(h_parent != h_dentry->d_parent))
+               goto out;
+       err = 0;
+
+       /*
+        * rmdir a dir may break the consistency on some filesystem.
+        * let's try heavy test.
+        */
+       err = -EACCES;
+       if (unlikely(au_test_h_perm(h_parent->d_inode, MAY_EXEC | MAY_WRITE)))
+               goto out;
+
+       h_latest = au_sio_lkup_one(&dentry->d_name, h_parent,
+                                  au_sbr(dentry->d_sb, bindex));
+       err = -EIO;
+       if (IS_ERR(h_latest))
+               goto out;
+       if (h_latest == h_dentry)
+               err = 0;
+       dput(h_latest);
+
+ out:
+       return err;
+}
+
+/*
+ * decide the branch where we operate for @dentry. the branch index will be set
+ * @rbcpup. after diciding it, 'pin' it and store the timestamps of the parent
+ * dir for reverting.
+ * when a new whiteout is necessary, create it.
+ */
+static struct dentry*
+lock_hdir_create_wh(struct dentry *dentry, int isdir, aufs_bindex_t *rbcpup,
+                   struct au_dtime *dt, struct au_pin *pin)
+{
+       struct dentry *wh_dentry;
+       struct super_block *sb;
+       struct path h_path;
+       int err, need_wh;
+       unsigned int udba;
+       aufs_bindex_t bcpup;
+
+       need_wh = au_wr_dir_need_wh(dentry, isdir, rbcpup);
+       wh_dentry = ERR_PTR(need_wh);
+       if (unlikely(need_wh < 0))
+               goto out;
+
+       sb = dentry->d_sb;
+       udba = au_opt_udba(sb);
+       bcpup = *rbcpup;
+       err = au_pin(pin, dentry, bcpup, udba,
+                    AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+       wh_dentry = ERR_PTR(err);
+       if (unlikely(err))
+               goto out;
+
+       h_path.dentry = au_pinned_h_parent(pin);
+       if (udba != AuOpt_UDBA_NONE
+           && au_dbstart(dentry) == bcpup) {
+               err = au_may_del(dentry, bcpup, h_path.dentry, isdir);
+               wh_dentry = ERR_PTR(err);
+               if (unlikely(err))
+                       goto out_unpin;
+       }
+
+       h_path.mnt = au_sbr_mnt(sb, bcpup);
+       au_dtime_store(dt, au_pinned_parent(pin), &h_path);
+       wh_dentry = NULL;
+       if (!need_wh)
+               goto out; /* success, no need to create whiteout */
+
+       wh_dentry = au_wh_create(dentry, bcpup, h_path.dentry);
+       if (!IS_ERR(wh_dentry))
+               goto out; /* success */
+       /* returns with the parent is locked and wh_dentry is dget-ed */
+
+ out_unpin:
+       au_unpin(pin);
+ out:
+       return wh_dentry;
+}
+
+/*
+ * when removing a dir, rename it to a unique temporary whiteout-ed name first
+ * in order to be revertible and save time for removing many child whiteouts
+ * under the dir.
+ * returns 1 when there are too many child whiteout and caller should remove
+ * them asynchronously. returns 0 when the number of children is enough small to
+ * remove now or the branch fs is a remote fs.
+ * otherwise return an error.
+ */
+static int renwh_and_rmdir(struct dentry *dentry, aufs_bindex_t bindex,
+                          struct au_nhash *whlist, struct inode *dir)
+{
+       int rmdir_later, err, dirwh;
+       struct dentry *h_dentry;
+       struct super_block *sb;
+
+       sb = dentry->d_sb;
+       h_dentry = au_h_dptr(dentry, bindex);
+       err = au_whtmp_ren(h_dentry, au_sbr(sb, bindex));
+       if (unlikely(err))
+               goto out;
+
+       /* stop monitoring */
+       au_hin_free(au_hi(dentry->d_inode, bindex));
+
+       if (!au_test_fs_remote(h_dentry->d_sb)) {
+               dirwh = au_sbi(sb)->si_dirwh;
+               rmdir_later = (dirwh <= 1);
+               if (!rmdir_later)
+                       rmdir_later = au_nhash_test_longer_wh(whlist, bindex,
+                                                             dirwh);
+               if (rmdir_later)
+                       return rmdir_later;
+       }
+
+       err = au_whtmp_rmdir(dir, bindex, h_dentry, whlist);
+       if (unlikely(err)) {
+               AuIOErr("rmdir %.*s, b%d failed, %d. ignored\n",
+                       AuDLNPair(h_dentry), bindex, err);
+               err = 0;
+       }
+
+ out:
+       return err;
+}
+
+/*
+ * final procedure for deleting a entry.
+ * maintain dentry and iattr.
+ */
+static void epilog(struct inode *dir, struct dentry *dentry,
+                  aufs_bindex_t bindex)
+{
+       struct inode *inode;
+
+       /*
+        * even if this is not a dir,
+        * set S_DEAD here since we need to detect the dead inode.
+        */
+       inode = dentry->d_inode;
+       if (!inode->i_nlink)
+               inode->i_flags |= S_DEAD;
+       d_drop(dentry);
+       inode->i_ctime = dir->i_ctime;
+
+       if (atomic_read(&dentry->d_count) == 1) {
+               au_set_h_dptr(dentry, au_dbstart(dentry), NULL);
+               au_update_dbstart(dentry);
+       }
+       if (au_ibstart(dir) == bindex)
+               au_cpup_attr_timesizes(dir);
+       dir->i_version++;
+}
+
+/*
+ * when an error happened, remove the created whiteout and revert everything.
+ */
+static int do_revert(int err, struct inode *dir, aufs_bindex_t bwh,
+                    struct dentry *wh_dentry, struct dentry *dentry,
+                    struct au_dtime *dt)
+{
+       int rerr;
+       struct path h_path = {
+               .dentry = wh_dentry,
+               .mnt    = au_sbr_mnt(dir->i_sb, bwh)
+       };
+
+       rerr = au_wh_unlink_dentry(au_h_iptr(dir, bwh), &h_path, dentry);
+       if (!rerr) {
+               au_set_dbwh(dentry, bwh);
+               au_dtime_revert(dt);
+               return 0;
+       }
+
+       AuIOErr("%.*s reverting whiteout failed(%d, %d)\n",
+               AuDLNPair(dentry), err, rerr);
+       return -EIO;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int aufs_unlink(struct inode *dir, struct dentry *dentry)
+{
+       int err;
+       aufs_bindex_t bwh, bindex, bstart;
+       struct au_dtime dt;
+       struct au_pin pin;
+       struct path h_path;
+       struct inode *inode, *h_dir;
+       struct dentry *parent, *wh_dentry;
+
+       IMustLock(dir);
+       inode = dentry->d_inode;
+       if (unlikely(!inode))
+               return -ENOENT; /* possible? */
+       IMustLock(inode);
+
+       aufs_read_lock(dentry, AuLock_DW);
+       parent = dentry->d_parent; /* dir inode is locked */
+       di_write_lock_parent(parent);
+
+       bstart = au_dbstart(dentry);
+       bwh = au_dbwh(dentry);
+       bindex = -1;
+       wh_dentry = lock_hdir_create_wh(dentry, /*isdir*/0, &bindex, &dt, &pin);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out;
+
+       h_path.mnt = au_sbr_mnt(dentry->d_sb, bstart);
+       h_path.dentry = au_h_dptr(dentry, bstart);
+       dget(h_path.dentry);
+       if (bindex == bstart) {
+               h_dir = au_pinned_h_dir(&pin);
+               err = vfsub_unlink(h_dir, &h_path, /*force*/0);
+       } else {
+               /* dir inode is locked */
+               h_dir = wh_dentry->d_parent->d_inode;
+               IMustLock(h_dir);
+               err = 0;
+       }
+
+       if (!err) {
+               drop_nlink(inode);
+               epilog(dir, dentry, bindex);
+
+               /* update target timestamps */
+               if (bindex == bstart) {
+                       vfsub_update_h_iattr(&h_path, /*did*/NULL); /*ignore*/
+                       inode->i_ctime = h_path.dentry->d_inode->i_ctime;
+               } else
+                       /* todo: this timestamp may be reverted later */
+                       inode->i_ctime = h_dir->i_ctime;
+               goto out_unlock; /* success */
+       }
+
+       /* revert */
+       if (wh_dentry) {
+               int rerr;
+
+               rerr = do_revert(err, dir, bwh, wh_dentry, dentry, &dt);
+               if (rerr)
+                       err = rerr;
+       }
+
+ out_unlock:
+       au_unpin(&pin);
+       dput(wh_dentry);
+       dput(h_path.dentry);
+ out:
+       di_write_unlock(parent);
+       aufs_read_unlock(dentry, AuLock_DW);
+       return err;
+}
+
+int aufs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+       int err, rmdir_later;
+       aufs_bindex_t bwh, bindex, bstart;
+       struct au_dtime dt;
+       struct au_pin pin;
+       struct inode *inode;
+       struct dentry *parent, *wh_dentry, *h_dentry;
+       struct au_whtmp_rmdir *args;
+
+       IMustLock(dir);
+       inode = dentry->d_inode;
+       err = -ENOENT; /* possible? */
+       if (unlikely(!inode))
+               goto out;
+       IMustLock(inode);
+
+       err = -ENOMEM;
+       args = au_whtmp_rmdir_alloc(dir->i_sb, GFP_NOFS);
+       if (unlikely(!args))
+               goto out;
+
+       aufs_read_lock(dentry, AuLock_DW | AuLock_FLUSH);
+       parent = dentry->d_parent; /* dir inode is locked */
+       di_write_lock_parent(parent);
+       err = au_test_empty(dentry, args->whlist);
+       if (unlikely(err))
+               goto out_args;
+
+       bstart = au_dbstart(dentry);
+       bwh = au_dbwh(dentry);
+       bindex = -1;
+       wh_dentry = lock_hdir_create_wh(dentry, /*isdir*/1, &bindex, &dt, &pin);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out_args;
+
+       h_dentry = au_h_dptr(dentry, bstart);
+       dget(h_dentry);
+       rmdir_later = 0;
+       if (bindex == bstart) {
+               err = renwh_and_rmdir(dentry, bstart, args->whlist, dir);
+               if (err > 0) {
+                       rmdir_later = err;
+                       err = 0;
+               }
+       } else {
+               /* stop monitoring */
+               au_hin_free(au_hi(inode, bstart));
+
+               /* dir inode is locked */
+               IMustLock(wh_dentry->d_parent->d_inode);
+               err = 0;
+       }
+
+       if (!err) {
+               clear_nlink(inode);
+               au_set_dbdiropq(dentry, -1);
+               epilog(dir, dentry, bindex);
+
+               if (rmdir_later) {
+                       au_whtmp_kick_rmdir(dir, bstart, h_dentry, args);
+                       args = NULL;
+               }
+
+               goto out_unlock; /* success */
+       }
+
+       /* revert */
+       AuLabel(revert);
+       if (wh_dentry) {
+               int rerr;
+
+               rerr = do_revert(err, dir, bwh, wh_dentry, dentry, &dt);
+               if (rerr)
+                       err = rerr;
+       }
+
+ out_unlock:
+       au_unpin(&pin);
+       dput(wh_dentry);
+       dput(h_dentry);
+ out_args:
+       di_write_unlock(parent);
+       aufs_read_unlock(dentry, AuLock_DW);
+       if (args)
+               au_whtmp_rmdir_free(args);
+ out:
+       return err;
+}
diff --git a/fs/aufs/i_op_ren.c b/fs/aufs/i_op_ren.c
new file mode 100644
index 0000000..3617d94
--- /dev/null
+++ b/fs/aufs/i_op_ren.c
@@ -0,0 +1,940 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode operation (rename entry)
+ * todo: this is crazy monster
+ */
+
+#include "aufs.h"
+
+enum { AuSRC, AuDST, AuSrcDst };
+enum { AuPARENT, AuCHILD, AuParentChild };
+
+#define AuRen_ISDIR    1
+#define AuRen_ISSAMEDIR        (1 << 1)
+#define AuRen_WHSRC    (1 << 2)
+#define AuRen_WHDST    (1 << 3)
+#define AuRen_MNT_WRITE        (1 << 4)
+#define AuRen_DT_DSTDIR        (1 << 5)
+#define AuRen_DIROPQ   (1 << 6)
+#define AuRen_CPUP     (1 << 7)
+#define au_ftest_ren(flags, name)      ((flags) & AuRen_##name)
+#define au_fset_ren(flags, name)       { (flags) |= AuRen_##name; }
+#define au_fclr_ren(flags, name)       { (flags) &= ~AuRen_##name; }
+
+struct au_ren_args {
+       struct {
+               struct dentry *dentry, *h_dentry, *parent, *h_parent,
+                       *wh_dentry;
+               struct inode *dir, *inode;
+               struct au_hinode *hdir;
+               struct au_dtime dt[AuParentChild];
+               aufs_bindex_t bstart;
+       } sd[AuSrcDst];
+
+#define src_dentry     sd[AuSRC].dentry
+#define src_dir                sd[AuSRC].dir
+#define src_inode      sd[AuSRC].inode
+#define src_h_dentry   sd[AuSRC].h_dentry
+#define src_parent     sd[AuSRC].parent
+#define src_h_parent   sd[AuSRC].h_parent
+#define src_wh_dentry  sd[AuSRC].wh_dentry
+#define src_hdir       sd[AuSRC].hdir
+#define src_h_dir      sd[AuSRC].hdir->hi_inode
+#define src_dt         sd[AuSRC].dt
+#define src_bstart     sd[AuSRC].bstart
+
+#define dst_dentry     sd[AuDST].dentry
+#define dst_dir                sd[AuDST].dir
+#define dst_inode      sd[AuDST].inode
+#define dst_h_dentry   sd[AuDST].h_dentry
+#define dst_parent     sd[AuDST].parent
+#define dst_h_parent   sd[AuDST].h_parent
+#define dst_wh_dentry  sd[AuDST].wh_dentry
+#define dst_hdir       sd[AuDST].hdir
+#define dst_h_dir      sd[AuDST].hdir->hi_inode
+#define dst_dt         sd[AuDST].dt
+#define dst_bstart     sd[AuDST].bstart
+
+       struct dentry *h_trap;
+       struct au_branch *br;
+       struct au_hinode *src_hinode;
+       struct path h_path;
+       struct au_nhash *whlist;
+       aufs_bindex_t btgt;
+
+       unsigned int flags;
+
+       struct au_whtmp_rmdir *thargs;
+       struct dentry *h_dst;
+};
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * functions for reverting.
+ * when an error happened in a single rename systemcall, we should revert
+ * everything as if nothing happend.
+ * we don't need to revert the copied-up/down the parent dir since they are
+ * harmless.
+ */
+
+#define RevertFailure(fmt, args...) do { \
+       AuIOErr("revert failure: " fmt " (%d, %d)\n", \
+               ##args, err, rerr); \
+       err = -EIO; \
+} while (0)
+
+static void au_ren_rev_diropq(int err, struct au_ren_args *a)
+{
+       int rerr;
+
+       au_hin_imtx_lock_nested(a->src_hinode, AuLsc_I_CHILD);
+       rerr = au_diropq_remove(a->src_dentry, a->btgt);
+       au_hin_imtx_unlock(a->src_hinode);
+       if (rerr)
+               RevertFailure("remove diropq %.*s", AuDLNPair(a->src_dentry));
+}
+
+
+static void au_ren_rev_rename(int err, struct au_ren_args *a)
+{
+       int rerr;
+
+       a->h_path.dentry = au_lkup_one(&a->src_dentry->d_name, a->src_h_parent,
+                                      a->br, /*nd*/NULL);
+       rerr = PTR_ERR(a->h_path.dentry);
+       if (IS_ERR(a->h_path.dentry)) {
+               RevertFailure("au_lkup_one %.*s", AuDLNPair(a->src_dentry));
+               return;
+       }
+
+       rerr = vfsub_rename(a->dst_h_dir,
+                           au_h_dptr(a->src_dentry, a->btgt),
+                           a->src_h_dir, &a->h_path);
+       d_drop(a->h_path.dentry);
+       dput(a->h_path.dentry);
+       /* au_set_h_dptr(a->src_dentry, a->btgt, NULL); */
+       if (rerr)
+               RevertFailure("rename %.*s", AuDLNPair(a->src_dentry));
+}
+
+static void au_ren_rev_cpup(int err, struct au_ren_args *a)
+{
+       int rerr;
+
+       a->h_path.dentry = a->dst_h_dentry;
+       rerr = vfsub_unlink(a->dst_h_dir, &a->h_path, /*force*/0);
+       au_set_h_dptr(a->src_dentry, a->btgt, NULL);
+       au_set_dbstart(a->src_dentry, a->src_bstart);
+       if (rerr)
+               RevertFailure("unlink %.*s", AuDLNPair(a->dst_h_dentry));
+}
+
+
+static void au_ren_rev_whtmp(int err, struct au_ren_args *a)
+{
+       int rerr;
+
+       a->h_path.dentry = au_lkup_one(&a->dst_dentry->d_name, a->dst_h_parent,
+                                      a->br, /*nd*/NULL);
+       rerr = PTR_ERR(a->h_path.dentry);
+       if (IS_ERR(a->h_path.dentry)) {
+               RevertFailure("lookup %.*s", AuDLNPair(a->dst_dentry));
+               return;
+       }
+       if (a->h_path.dentry->d_inode) {
+               d_drop(a->h_path.dentry);
+               dput(a->h_path.dentry);
+               return;
+       }
+
+       rerr = vfsub_rename(a->dst_h_dir, a->h_dst, a->dst_h_dir, &a->h_path);
+       d_drop(a->h_path.dentry);
+       dput(a->h_path.dentry);
+       if (!rerr) {
+               au_set_h_dptr(a->dst_dentry, a->btgt, NULL);
+               au_set_h_dptr(a->dst_dentry, a->btgt, dget(a->h_dst));
+       } else
+               RevertFailure("rename %.*s", AuDLNPair(a->h_dst));
+}
+
+static void au_ren_rev_whsrc(int err, struct au_ren_args *a)
+{
+       int rerr;
+
+       a->h_path.dentry = a->src_wh_dentry;
+       rerr = au_wh_unlink_dentry(a->src_h_dir, &a->h_path, a->src_dentry);
+       if (rerr)
+               RevertFailure("unlink %.*s", AuDLNPair(a->src_wh_dentry));
+}
+
+static void au_ren_rev_drop(struct au_ren_args *a)
+{
+       struct dentry *d, *h_d;
+       int i;
+       aufs_bindex_t bend, bindex;
+
+       for (i = 0; i < AuSrcDst; i++) {
+               d = a->sd[i].dentry;
+               d_drop(d);
+               bend = au_dbend(d);
+               for (bindex = au_dbstart(d); bindex <= bend; bindex++) {
+                       h_d = au_h_dptr(d, bindex);
+                       if (h_d)
+                               d_drop(h_d);
+               }
+       }
+
+       au_update_dbstart(a->dst_dentry);
+       if (a->thargs)
+               d_drop(a->h_dst);
+}
+#undef RevertFailure
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * when we have to copyup the renaming entry, do it with the rename-target name
+ * in order to minimize the cost (the later actual rename is unnecessary).
+ * otherwise rename it on the target branch.
+ */
+static int au_ren_or_cpup(struct au_ren_args *a)
+{
+       int err;
+       struct dentry *d;
+
+       d = a->src_dentry;
+       if (au_dbstart(d) == a->btgt) {
+               a->h_path.dentry = a->dst_h_dentry;
+               if (au_ftest_ren(a->flags, DIROPQ)
+                   && au_dbdiropq(d) == a->btgt)
+                       au_fclr_ren(a->flags, DIROPQ);
+               AuDebugOn(au_dbstart(d) != a->btgt);
+               err = vfsub_rename(a->src_h_dir, au_h_dptr(d, a->btgt),
+                                  a->dst_h_dir, &a->h_path);
+       } else {
+               struct mutex *h_mtx = &a->src_h_dentry->d_inode->i_mutex;
+
+               au_fset_ren(a->flags, CPUP);
+               mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+               au_set_dbstart(d, a->btgt);
+               au_set_h_dptr(d, a->btgt, dget(a->dst_h_dentry));
+               err = au_sio_cpup_single(d, a->btgt, a->src_bstart, -1,
+                                        !AuCpup_DTIME, a->dst_parent);
+               if (unlikely(err)) {
+                       au_set_h_dptr(d, a->btgt, NULL);
+                       au_set_dbstart(d, a->src_bstart);
+               }
+               mutex_unlock(h_mtx);
+       }
+
+       return err;
+}
+
+/* cf. aufs_rmdir() */
+static int au_ren_del_whtmp(struct au_ren_args *a)
+{
+       int err;
+       struct inode *dir;
+
+       dir = a->dst_dir;
+       if (!au_nhash_test_longer_wh(a->whlist, a->btgt,
+                                    au_sbi(dir->i_sb)->si_dirwh)
+           || au_test_fs_remote(a->h_dst->d_sb)) {
+               err = au_whtmp_rmdir(dir, a->btgt, a->h_dst, a->whlist);
+               if (unlikely(err))
+                       AuWarn("failed removing whtmp dir %.*s (%d), "
+                              "ignored.\n", AuDLNPair(a->h_dst), err);
+       } else {
+               au_nhash_wh_free(a->thargs->whlist, /*bend*/0);
+               a->thargs->whlist = a->whlist;
+               a->whlist = NULL;
+               au_whtmp_kick_rmdir(dir, a->btgt, a->h_dst, a->thargs);
+               dput(a->h_dst);
+               a->thargs = NULL;
+       }
+
+       return 0;
+}
+
+/* make it 'opaque' dir. */
+static int au_ren_diropq(struct au_ren_args *a)
+{
+       int err;
+       struct dentry *diropq;
+
+       err = 0;
+       a->src_hinode = au_hi(a->src_inode, a->btgt);
+       au_hin_imtx_lock_nested(a->src_hinode, AuLsc_I_CHILD);
+       diropq = au_diropq_create(a->src_dentry, a->btgt);
+       au_hin_imtx_unlock(a->src_hinode);
+       if (IS_ERR(diropq))
+               err = PTR_ERR(diropq);
+       dput(diropq);
+
+       return err;
+}
+
+static int do_rename(struct au_ren_args *a)
+{
+       int err;
+       struct dentry *d, *h_d;
+
+       /* prepare workqueue args for asynchronous rmdir */
+       h_d = a->dst_h_dentry;
+       if (au_ftest_ren(a->flags, ISDIR) && h_d->d_inode) {
+               err = -ENOMEM;
+               a->thargs = au_whtmp_rmdir_alloc(a->src_dentry->d_sb, GFP_NOFS);
+               if (unlikely(!a->thargs))
+                       goto out;
+               a->h_dst = dget(h_d);
+       }
+
+       /* create whiteout for src_dentry */
+       if (au_ftest_ren(a->flags, WHSRC)) {
+               a->src_wh_dentry
+                       = au_wh_create(a->src_dentry, a->btgt, a->src_h_parent);
+               err = PTR_ERR(a->src_wh_dentry);
+               if (IS_ERR(a->src_wh_dentry))
+                       goto out_thargs;
+       }
+
+       /* lookup whiteout for dentry */
+       if (au_ftest_ren(a->flags, WHDST)) {
+               h_d = au_wh_lkup(a->dst_h_parent, &a->dst_dentry->d_name,
+                                a->br);
+               err = PTR_ERR(h_d);
+               if (IS_ERR(h_d))
+                       goto out_whsrc;
+               if (!h_d->d_inode)
+                       dput(h_d);
+               else
+                       a->dst_wh_dentry = h_d;
+       }
+
+       /* rename dentry to tmpwh */
+       if (a->thargs) {
+               err = au_whtmp_ren(a->dst_h_dentry, a->br);
+               if (unlikely(err))
+                       goto out_whdst;
+
+               d = a->dst_dentry;
+               au_set_h_dptr(d, a->btgt, NULL);
+               err = au_lkup_neg(d, a->btgt);
+               if (unlikely(err))
+                       goto out_whtmp;
+               a->dst_h_dentry = au_h_dptr(d, a->btgt);
+       }
+
+       /* cpup src */
+       if (a->dst_h_dentry->d_inode && a->src_bstart != a->btgt) {
+               struct mutex *h_mtx = &a->src_h_dentry->d_inode->i_mutex;
+
+               mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+               err = au_sio_cpup_simple(a->src_dentry, a->btgt, -1,
+                                        !AuCpup_DTIME);
+               mutex_unlock(h_mtx);
+               if (unlikely(err))
+                       goto out_whtmp;
+       }
+
+       /* rename by vfs_rename or cpup */
+       d = a->dst_dentry;
+       if (au_ftest_ren(a->flags, ISDIR)
+           && (a->dst_wh_dentry
+               || au_dbdiropq(d) == a->btgt
+               /* hide the lower to keep xino */
+               || a->btgt < au_dbend(d)
+               || au_opt_test(au_mntflags(d->d_sb), ALWAYS_DIROPQ)))
+               au_fset_ren(a->flags, DIROPQ);
+       err = au_ren_or_cpup(a);
+       if (unlikely(err))
+               /* leave the copied-up one */
+               goto out_whtmp;
+
+       /* make dir opaque */
+       if (au_ftest_ren(a->flags, DIROPQ)) {
+               err = au_ren_diropq(a);
+               if (unlikely(err))
+                       goto out_rename;
+       }
+
+       /* update target timestamps */
+       AuDebugOn(au_dbstart(a->src_dentry) != a->btgt);
+       a->h_path.dentry = au_h_dptr(a->src_dentry, a->btgt);
+       vfsub_update_h_iattr(&a->h_path, /*did*/NULL); /*ignore*/
+       a->src_inode->i_ctime = a->h_path.dentry->d_inode->i_ctime;
+
+       /* remove whiteout for dentry */
+       if (a->dst_wh_dentry) {
+               a->h_path.dentry = a->dst_wh_dentry;
+               err = au_wh_unlink_dentry(a->dst_h_dir, &a->h_path,
+                                         a->dst_dentry);
+               if (unlikely(err))
+                       goto out_diropq;
+       }
+
+       /* remove whtmp */
+       if (a->thargs)
+               au_ren_del_whtmp(a); /* ignore this error */
+
+       err = 0;
+       goto out_success;
+
+ out_diropq:
+       if (au_ftest_ren(a->flags, DIROPQ))
+               au_ren_rev_diropq(err, a);
+ out_rename:
+       if (!au_ftest_ren(a->flags, CPUP))
+               au_ren_rev_rename(err, a);
+       else
+               au_ren_rev_cpup(err, a);
+ out_whtmp:
+       if (a->thargs)
+               au_ren_rev_whtmp(err, a);
+ out_whdst:
+       dput(a->dst_wh_dentry);
+       a->dst_wh_dentry = NULL;
+ out_whsrc:
+       if (a->src_wh_dentry)
+               au_ren_rev_whsrc(err, a);
+       au_ren_rev_drop(a);
+ out_success:
+       dput(a->src_wh_dentry);
+       dput(a->dst_wh_dentry);
+ out_thargs:
+       if (a->thargs) {
+               dput(a->h_dst);
+               au_whtmp_rmdir_free(a->thargs);
+               a->thargs = NULL;
+       }
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * test if @dentry dir can be rename destination or not.
+ * success means, it is a logically empty dir.
+ */
+static int may_rename_dstdir(struct dentry *dentry, struct au_nhash *whlist)
+{
+       return au_test_empty(dentry, whlist);
+}
+
+/*
+ * test if @dentry dir can be rename source or not.
+ * if it can, return 0 and @children is filled.
+ * success means,
+ * - it is a logically empty dir.
+ * - or, it exists on writable branch and has no children including whiteouts
+ *       on the lower branch.
+ */
+static int may_rename_srcdir(struct dentry *dentry, aufs_bindex_t btgt)
+{
+       int err;
+       aufs_bindex_t bstart;
+
+       bstart = au_dbstart(dentry);
+       if (bstart != btgt) {
+               struct au_nhash *whlist;
+
+               whlist = au_nhash_alloc(dentry->d_sb, /*bend*/0, GFP_NOFS);
+               err = PTR_ERR(whlist);
+               if (IS_ERR(whlist))
+                       goto out;
+               err = au_test_empty(dentry, whlist);
+               au_nhash_wh_free(whlist, /*bend*/0);
+               goto out;
+       }
+
+       if (bstart == au_dbtaildir(dentry))
+               return 0; /* success */
+
+       err = au_test_empty_lower(dentry);
+
+ out:
+       if (err == -ENOTEMPTY) {
+               AuWarn1("renaming dir who has child(ren) on multiple branches,"
+                       " is not supported\n");
+               err = -EXDEV;
+       }
+       return err;
+}
+
+/* side effect: sets whlist and h_dentry */
+static int au_ren_may_dir(struct au_ren_args *a)
+{
+       int err;
+       struct dentry *d;
+
+       err = -ENOMEM;
+       d = a->dst_dentry;
+       a->whlist = au_nhash_alloc(d->d_sb, /*bend*/0, GFP_NOFS);
+       if (unlikely(!a->whlist))
+               goto out;
+
+       err = 0;
+       if (au_ftest_ren(a->flags, ISDIR) && a->dst_inode) {
+               au_set_dbstart(d, a->dst_bstart);
+               err = may_rename_dstdir(d, a->whlist);
+               au_set_dbstart(d, a->btgt);
+       }
+       a->dst_h_dentry = au_h_dptr(d, au_dbstart(d));
+       if (unlikely(err))
+               goto out;
+
+       d = a->src_dentry;
+       a->src_h_dentry = au_h_dptr(d, au_dbstart(d));
+       if (au_ftest_ren(a->flags, ISDIR)) {
+               err = may_rename_srcdir(d, a->btgt);
+               if (unlikely(err)) {
+                       au_nhash_wh_free(a->whlist, /*bend*/0);
+                       a->whlist = NULL;
+               }
+       }
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * simple tests for rename.
+ * following the checks in vfs, plus the parent-child relationship.
+ */
+static int au_may_ren(struct au_ren_args *a)
+{
+       int err, isdir;
+       struct inode *h_inode;
+
+       if (a->src_bstart == a->btgt) {
+               err = au_may_del(a->src_dentry, a->btgt, a->src_h_parent,
+                                au_ftest_ren(a->flags, ISDIR));
+               if (unlikely(err))
+                       goto out;
+               err = -EINVAL;
+               if (unlikely(a->src_h_dentry == a->h_trap))
+                       goto out;
+       }
+
+       err = 0;
+       if (a->dst_bstart != a->btgt)
+               goto out;
+
+       err = -EIO;
+       h_inode = a->dst_h_dentry->d_inode;
+       isdir = !!au_ftest_ren(a->flags, ISDIR);
+       if (!a->dst_dentry->d_inode) {
+               if (unlikely(h_inode))
+                       goto out;
+               err = au_may_add(a->dst_dentry, a->btgt, a->dst_h_parent,
+                                isdir);
+       } else {
+               if (unlikely(!h_inode || !h_inode->i_nlink))
+                       goto out;
+               err = au_may_del(a->dst_dentry, a->btgt, a->dst_h_parent,
+                                isdir);
+               if (unlikely(err))
+                       goto out;
+               err = -ENOTEMPTY;
+               if (unlikely(a->dst_h_dentry == a->h_trap))
+                       goto out;
+               err = 0;
+       }
+
+ out:
+       if (unlikely(err == -ENOENT || err == -EEXIST))
+               err = -EIO;
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * locking order
+ * (VFS)
+ * - src_dir and dir by lock_rename()
+ * - inode if exitsts
+ * (aufs)
+ * - lock all
+ *   + src_dentry and dentry by aufs_read_and_write_lock2() which calls,
+ *     + si_read_lock
+ *     + di_write_lock2_child()
+ *       + di_write_lock_child()
+ *        + ii_write_lock_child()
+ *       + di_write_lock_child2()
+ *        + ii_write_lock_child2()
+ *     + src_parent and parent
+ *       + di_write_lock_parent()
+ *        + ii_write_lock_parent()
+ *       + di_write_lock_parent2()
+ *        + ii_write_lock_parent2()
+ *   + lower src_dir and dir by vfsub_lock_rename()
+ *   + verify the every relationships between child and parent. if any
+ *     of them failed, unlock all and return -EBUSY.
+ */
+static void au_ren_unlock(struct au_ren_args *a)
+{
+       struct super_block *sb;
+
+       sb = a->dst_dentry->d_sb;
+       if (au_ftest_ren(a->flags, MNT_WRITE))
+               mnt_drop_write(a->br->br_mnt);
+       vfsub_unlock_rename(a->src_h_parent, a->src_hdir,
+                           a->dst_h_parent, a->dst_hdir);
+}
+
+static int au_ren_lock(struct au_ren_args *a)
+{
+       int err;
+       unsigned int udba;
+
+       err = 0;
+       a->src_h_parent = au_h_dptr(a->src_parent, a->btgt);
+       a->src_hdir = au_hi(a->src_dir, a->btgt);
+       a->dst_h_parent = au_h_dptr(a->dst_parent, a->btgt);
+       a->dst_hdir = au_hi(a->dst_dir, a->btgt);
+       a->h_trap = vfsub_lock_rename(a->src_h_parent, a->src_hdir,
+                                     a->dst_h_parent, a->dst_hdir);
+       udba = au_opt_udba(a->src_dentry->d_sb);
+       if (au_dbstart(a->src_dentry) == a->btgt)
+               err = au_h_verify(a->src_h_dentry, udba,
+                                 a->src_h_parent->d_inode, a->src_h_parent,
+                                 a->br);
+       if (!err && au_dbstart(a->dst_dentry) == a->btgt)
+               err = au_h_verify(a->dst_h_dentry, udba,
+                                 a->dst_h_parent->d_inode, a->dst_h_parent,
+                                 a->br);
+       if (!err) {
+               err = mnt_want_write(a->br->br_mnt);
+               if (unlikely(err))
+                       goto out_unlock;
+               au_fset_ren(a->flags, MNT_WRITE);
+               goto out; /* success */
+       }
+
+       err = au_busy_or_stale();
+
+ out_unlock:
+       au_ren_unlock(a);
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void au_ren_refresh_dir(struct au_ren_args *a)
+{
+       struct inode *dir;
+
+       dir = a->dst_dir;
+       dir->i_version++;
+       if (au_ftest_ren(a->flags, ISDIR)) {
+               /* is this updating defined in POSIX? */
+               au_cpup_attr_timesizes(a->src_inode);
+               au_cpup_attr_nlink(dir, /*force*/1);
+               if (a->dst_inode) {
+                       clear_nlink(a->dst_inode);
+                       au_cpup_attr_timesizes(a->dst_inode);
+               }
+       }
+       if (au_ibstart(dir) == a->btgt)
+               au_cpup_attr_timesizes(dir);
+
+       if (au_ftest_ren(a->flags, ISSAMEDIR))
+               return;
+
+       dir = a->src_dir;
+       dir->i_version++;
+       if (au_ftest_ren(a->flags, ISDIR))
+               au_cpup_attr_nlink(dir, /*force*/1);
+       if (au_ibstart(dir) == a->btgt)
+               au_cpup_attr_timesizes(dir);
+}
+
+static void au_ren_refresh(struct au_ren_args *a)
+{
+       aufs_bindex_t bend, bindex;
+       struct dentry *d, *h_d;
+       struct inode *i, *h_i;
+       struct super_block *sb;
+
+       d = a->src_dentry;
+       au_set_dbwh(d, -1);
+       bend = au_dbend(d);
+       for (bindex = a->btgt + 1; bindex <= bend; bindex++) {
+               h_d = au_h_dptr(d, bindex);
+               if (h_d)
+                       au_set_h_dptr(d, bindex, NULL);
+       }
+       au_set_dbend(d, a->btgt);
+
+       sb = d->d_sb;
+       i = a->src_inode;
+       if (au_opt_test(au_mntflags(sb), PLINK) && au_plink_test(i))
+               return; /* success */
+
+       bend = au_ibend(i);
+       for (bindex = a->btgt + 1; bindex <= bend; bindex++) {
+               h_i = au_h_iptr(i, bindex);
+               if (h_i) {
+                       au_xino_write0(sb, bindex, h_i->i_ino, 0);
+                       /* ignore this error */
+                       au_set_h_iptr(i, bindex, NULL, 0);
+               }
+       }
+       au_set_ibend(i, a->btgt);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* mainly for link(2) and rename(2) */
+int au_wbr(struct dentry *dentry, aufs_bindex_t btgt)
+{
+       aufs_bindex_t bdiropq, bwh;
+       struct dentry *parent;
+       struct au_branch *br;
+
+       parent = dentry->d_parent;
+       IMustLock(parent->d_inode); /* dir is locked */
+
+       bdiropq = au_dbdiropq(parent);
+       bwh = au_dbwh(dentry);
+       br = au_sbr(dentry->d_sb, btgt);
+       if (au_br_rdonly(br)
+           || (0 <= bdiropq && bdiropq < btgt)
+           || (0 <= bwh && bwh < btgt))
+               btgt = -1;
+
+       AuDbg("btgt %d\n", btgt);
+       return btgt;
+}
+
+/* sets src_bstart, dst_bstart and btgt */
+static int au_ren_wbr(struct au_ren_args *a)
+{
+       int err;
+       struct au_wr_dir_args wr_dir_args = {
+               /* .force_btgt  = -1, */
+               .flags          = AuWrDir_ADD_ENTRY
+       };
+
+       a->src_bstart = au_dbstart(a->src_dentry);
+       a->dst_bstart = au_dbstart(a->dst_dentry);
+       if (au_ftest_ren(a->flags, ISDIR))
+               au_fset_wrdir(wr_dir_args.flags, ISDIR);
+       wr_dir_args.force_btgt = a->src_bstart;
+       if (a->dst_inode && a->dst_bstart < a->src_bstart)
+               wr_dir_args.force_btgt = a->dst_bstart;
+       wr_dir_args.force_btgt = au_wbr(a->dst_dentry, wr_dir_args.force_btgt);
+       err = au_wr_dir(a->dst_dentry, a->src_dentry, &wr_dir_args);
+       a->btgt = err;
+
+       return err;
+}
+
+static void au_ren_dt(struct au_ren_args *a)
+{
+       a->h_path.dentry = a->src_h_parent;
+       au_dtime_store(a->src_dt + AuPARENT, a->src_parent, &a->h_path);
+       if (!au_ftest_ren(a->flags, ISSAMEDIR)) {
+               a->h_path.dentry = a->dst_h_parent;
+               au_dtime_store(a->dst_dt + AuPARENT, a->dst_parent, &a->h_path);
+       }
+
+       au_fclr_ren(a->flags, DT_DSTDIR);
+       if (!au_ftest_ren(a->flags, ISDIR))
+               return;
+
+       a->h_path.dentry = a->src_h_dentry;
+       au_dtime_store(a->src_dt + AuCHILD, a->src_dentry, &a->h_path);
+       if (a->dst_h_dentry->d_inode) {
+               au_fset_ren(a->flags, DT_DSTDIR);
+               a->h_path.dentry = a->dst_h_dentry;
+               au_dtime_store(a->dst_dt + AuCHILD, a->dst_dentry, &a->h_path);
+       }
+}
+
+static void au_ren_rev_dt(int err, struct au_ren_args *a)
+{
+       struct dentry *h_d;
+       struct mutex *h_mtx;
+
+       au_dtime_revert(a->src_dt + AuPARENT);
+       if (!au_ftest_ren(a->flags, ISSAMEDIR))
+               au_dtime_revert(a->dst_dt + AuPARENT);
+
+       if (au_ftest_ren(a->flags, ISDIR) && err != -EIO) {
+               h_d = a->src_dt[AuCHILD].dt_h_path.dentry;
+               h_mtx = &h_d->d_inode->i_mutex;
+               mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+               au_dtime_revert(a->src_dt + AuCHILD);
+               mutex_unlock(h_mtx);
+
+               if (au_ftest_ren(a->flags, DT_DSTDIR)) {
+                       h_d = a->dst_dt[AuCHILD].dt_h_path.dentry;
+                       h_mtx = &h_d->d_inode->i_mutex;
+                       mutex_lock_nested(h_mtx, AuLsc_I_CHILD);
+                       au_dtime_revert(a->dst_dt + AuCHILD);
+                       mutex_unlock(h_mtx);
+               }
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int aufs_rename(struct inode *_src_dir, struct dentry *_src_dentry,
+               struct inode *_dst_dir, struct dentry *_dst_dentry)
+{
+       int err;
+       /* reduce stack space */
+       struct au_ren_args *a;
+
+       IMustLock(_src_dir);
+       IMustLock(_dst_dir);
+
+       err = -ENOMEM;
+       BUILD_BUG_ON(sizeof(*a) > PAGE_SIZE);
+       a = kzalloc(sizeof(*a), GFP_NOFS);
+       if (unlikely(!a))
+               goto out;
+
+       a->src_dir = _src_dir;
+       a->src_dentry = _src_dentry;
+       a->src_inode = a->src_dentry->d_inode;
+       a->src_parent = a->src_dentry->d_parent; /* dir inode is locked */
+       a->dst_dir = _dst_dir;
+       a->dst_dentry = _dst_dentry;
+       a->dst_inode = a->dst_dentry->d_inode;
+       a->dst_parent = a->dst_dentry->d_parent; /* dir inode is locked */
+       if (a->dst_inode) {
+               IMustLock(a->dst_inode);
+               au_igrab(a->dst_inode);
+       }
+
+       err = -ENOTDIR;
+       if (S_ISDIR(a->src_inode->i_mode)) {
+               au_fset_ren(a->flags, ISDIR);
+               if (unlikely(a->dst_inode && !S_ISDIR(a->dst_inode->i_mode)))
+                       goto out_free;
+               aufs_read_and_write_lock2(a->dst_dentry, a->src_dentry,
+                                         AuLock_DIR | AuLock_FLUSH);
+       } else
+               aufs_read_and_write_lock2(a->dst_dentry, a->src_dentry,
+                                         AuLock_FLUSH);
+
+       au_fset_ren(a->flags, ISSAMEDIR); /* temporary */
+       di_write_lock_parent(a->dst_parent);
+
+       /* which branch we process */
+       err = au_ren_wbr(a);
+       if (unlikely(err < 0))
+               goto out_unlock;
+       a->br = au_sbr(a->dst_dentry->d_sb, a->btgt);
+       a->h_path.mnt = a->br->br_mnt;
+
+       /* are they available to be renamed */
+       err = au_ren_may_dir(a);
+       if (unlikely(err))
+               goto out_unlock;
+
+       /* prepare the writable parent dir on the same branch */
+       if (a->dst_bstart == a->btgt) {
+               au_fset_ren(a->flags, WHDST);
+       } else {
+               err = au_cpup_dirs(a->dst_dentry, a->btgt);
+               if (unlikely(err))
+                       goto out_children;
+       }
+
+       if (a->src_dir != a->dst_dir) {
+               /*
+                * this temporary unlock is safe,
+                * because both dir->i_mutex are locked.
+                */
+               di_write_unlock(a->dst_parent);
+               di_write_lock_parent(a->src_parent);
+               err = au_wr_dir_need_wh(a->src_dentry,
+                                       au_ftest_ren(a->flags, ISDIR),
+                                       &a->btgt);
+               di_write_unlock(a->src_parent);
+               di_write_lock2_parent(a->src_parent, a->dst_parent, /*isdir*/1);
+               au_fclr_ren(a->flags, ISSAMEDIR);
+       } else
+               err = au_wr_dir_need_wh(a->src_dentry,
+                                       au_ftest_ren(a->flags, ISDIR),
+                                       &a->btgt);
+       if (unlikely(err < 0))
+               goto out_children;
+       if (err)
+               au_fset_ren(a->flags, WHSRC);
+
+       /* lock them all */
+       err = au_ren_lock(a);
+       if (unlikely(err))
+               goto out_children;
+
+       if (!au_opt_test(au_mntflags(a->dst_dir->i_sb), UDBA_NONE)) {
+               err = au_may_ren(a);
+               if (unlikely(err))
+                       goto out_hdir;
+       }
+
+       /* store timestamps to be revertible */
+       au_ren_dt(a);
+
+       /* here we go */
+       err = do_rename(a);
+       if (unlikely(err))
+               goto out_dt;
+
+       /* update dir attributes */
+       au_ren_refresh_dir(a);
+
+       /* dput/iput all lower dentries */
+       au_ren_refresh(a);
+
+       goto out_hdir; /* success */
+
+ out_dt:
+       au_ren_rev_dt(err, a);
+ out_hdir:
+       au_ren_unlock(a);
+ out_children:
+       if (a->whlist)
+               au_nhash_wh_free(a->whlist, /*bend*/0);
+ out_unlock:
+       if (unlikely(err && au_ftest_ren(a->flags, ISDIR))) {
+               au_update_dbstart(a->dst_dentry);
+               d_drop(a->dst_dentry);
+       }
+       if (!err) {
+               d_move(a->src_dentry, a->dst_dentry);
+               if (a->dst_inode
+                   && (a->dst_inode->i_nlink <= 1
+                       || au_ftest_ren(a->flags, ISDIR)))
+                       a->dst_inode->i_flags |= S_DEAD;
+       }
+       if (au_ftest_ren(a->flags, ISSAMEDIR))
+               di_write_unlock(a->dst_parent);
+       else
+               di_write_unlock2(a->src_parent, a->dst_parent);
+       aufs_read_and_write_unlock2(a->dst_dentry, a->src_dentry);
+ out_free:
+       iput(a->dst_inode);
+       if (a->thargs)
+               au_whtmp_rmdir_free(a->thargs);
+       kfree(a);
+ out:
+       return err;
+}
diff --git a/fs/aufs/iinfo.c b/fs/aufs/iinfo.c
new file mode 100644
index 0000000..b1cff91
--- /dev/null
+++ b/fs/aufs/iinfo.c
@@ -0,0 +1,262 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode private data
+ */
+
+#include "aufs.h"
+
+struct inode *au_h_iptr(struct inode *inode, aufs_bindex_t bindex)
+{
+       struct inode *h_inode;
+
+       h_inode = au_ii(inode)->ii_hinode[0 + bindex].hi_inode;
+       AuDebugOn(h_inode && atomic_read(&h_inode->i_count) <= 0);
+       return h_inode;
+}
+
+/* todo: hard/soft set? */
+void au_set_ibstart(struct inode *inode, aufs_bindex_t bindex)
+{
+       struct au_iinfo *iinfo = au_ii(inode);
+       struct inode *h_inode;
+
+       iinfo->ii_bstart = bindex;
+       h_inode = iinfo->ii_hinode[bindex + 0].hi_inode;
+       if (h_inode)
+               au_cpup_igen(inode, h_inode);
+}
+
+void au_hiput(struct au_hinode *hinode)
+{
+       au_hin_free(hinode);
+       dput(hinode->hi_whdentry);
+       iput(hinode->hi_inode);
+}
+
+unsigned int au_hi_flags(struct inode *inode, int isdir)
+{
+       unsigned int flags;
+       const unsigned int mnt_flags = au_mntflags(inode->i_sb);
+
+       flags = 0;
+       if (au_opt_test(mnt_flags, XINO))
+               au_fset_hi(flags, XINO);
+       if (isdir && au_opt_test(mnt_flags, UDBA_HINOTIFY))
+               au_fset_hi(flags, HINOTIFY);
+       return flags;
+}
+
+void au_set_h_iptr(struct inode *inode, aufs_bindex_t bindex,
+                  struct inode *h_inode, unsigned int flags)
+{
+       struct au_hinode *hinode;
+       struct inode *hi;
+       struct au_iinfo *iinfo = au_ii(inode);
+
+       hinode = iinfo->ii_hinode + bindex;
+       hi = hinode->hi_inode;
+       AuDebugOn(h_inode && atomic_read(&h_inode->i_count) <= 0);
+       AuDebugOn(h_inode && hi);
+
+       if (hi)
+               au_hiput(hinode);
+       hinode->hi_inode = h_inode;
+       if (h_inode) {
+               int err;
+               struct super_block *sb = inode->i_sb;
+               struct au_branch *br;
+
+               if (bindex == iinfo->ii_bstart)
+                       au_cpup_igen(inode, h_inode);
+               br = au_sbr(sb, bindex);
+               hinode->hi_id = br->br_id;
+               if (au_ftest_hi(flags, XINO)) {
+                       err = au_xino_write(sb, bindex, h_inode->i_ino,
+                                           inode->i_ino);
+                       if (unlikely(err))
+                               AuIOErr1("failed au_xino_write() %d\n", err);
+               }
+
+               if (au_ftest_hi(flags, HINOTIFY)
+                   && au_br_hinotifyable(br->br_perm)) {
+                       err = au_hin_alloc(hinode, inode, h_inode);
+                       if (unlikely(err))
+                               AuIOErr1("au_hin_alloc() %d\n", err);
+               }
+       }
+}
+
+void au_set_hi_wh(struct inode *inode, aufs_bindex_t bindex,
+                 struct dentry *h_wh)
+{
+       struct au_hinode *hinode;
+
+       hinode = au_ii(inode)->ii_hinode + bindex;
+       AuDebugOn(hinode->hi_whdentry);
+       hinode->hi_whdentry = h_wh;
+}
+
+void au_update_iigen(struct inode *inode)
+{
+       atomic_set(&au_ii(inode)->ii_generation, au_sigen(inode->i_sb));
+       /* smp_mb(); */ /* atomic_set */
+}
+
+/* it may be called at remount time, too */
+void au_update_brange(struct inode *inode, int do_put_zero)
+{
+       struct au_iinfo *iinfo;
+
+       iinfo = au_ii(inode);
+       if (!iinfo || iinfo->ii_bstart < 0)
+               return;
+
+       if (do_put_zero) {
+               aufs_bindex_t bindex;
+
+               for (bindex = iinfo->ii_bstart; bindex <= iinfo->ii_bend;
+                    bindex++) {
+                       struct inode *h_i;
+
+                       h_i = iinfo->ii_hinode[0 + bindex].hi_inode;
+                       if (h_i && !h_i->i_nlink)
+                               au_set_h_iptr(inode, bindex, NULL, 0);
+               }
+       }
+
+       iinfo->ii_bstart = -1;
+       while (++iinfo->ii_bstart <= iinfo->ii_bend)
+               if (iinfo->ii_hinode[0 + iinfo->ii_bstart].hi_inode)
+                       break;
+       if (iinfo->ii_bstart > iinfo->ii_bend) {
+               iinfo->ii_bstart = -1;
+               iinfo->ii_bend = -1;
+               return;
+       }
+
+       iinfo->ii_bend++;
+       while (0 <= --iinfo->ii_bend)
+               if (iinfo->ii_hinode[0 + iinfo->ii_bend].hi_inode)
+                       break;
+       AuDebugOn(iinfo->ii_bstart > iinfo->ii_bend || iinfo->ii_bend < 0);
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_iinfo_init(struct inode *inode)
+{
+       struct au_iinfo *iinfo;
+       struct super_block *sb;
+       int nbr, i;
+
+       sb = inode->i_sb;
+       iinfo = &(container_of(inode, struct au_icntnr, vfs_inode)->iinfo);
+       nbr = au_sbend(sb) + 1;
+       if (unlikely(nbr <= 0))
+               nbr = 1;
+       iinfo->ii_hinode = kcalloc(nbr, sizeof(*iinfo->ii_hinode), GFP_NOFS);
+       if (iinfo->ii_hinode) {
+               for (i = 0; i < nbr; i++)
+                       iinfo->ii_hinode[i].hi_id = -1;
+
+               atomic_set(&iinfo->ii_generation, au_sigen(sb));
+               /* smp_mb(); */ /* atomic_set */
+               init_rwsem(&iinfo->ii_rwsem);
+               iinfo->ii_bstart = -1;
+               iinfo->ii_bend = -1;
+               iinfo->ii_vdir = NULL;
+               return 0;
+       }
+       return -ENOMEM;
+}
+
+int au_ii_realloc(struct au_iinfo *iinfo, int nbr)
+{
+       int err, sz;
+       struct au_hinode *hip;
+
+       err = -ENOMEM;
+       sz = sizeof(*hip) * (iinfo->ii_bend + 1);
+       if (!sz)
+               sz = sizeof(*hip);
+       hip = au_kzrealloc(iinfo->ii_hinode, sz, sizeof(*hip) * nbr, GFP_NOFS);
+       if (hip) {
+               iinfo->ii_hinode = hip;
+               err = 0;
+       }
+
+       return err;
+}
+
+static int au_iinfo_write0(struct super_block *sb, struct au_hinode *hinode,
+                          ino_t ino)
+{
+       int err;
+       aufs_bindex_t bindex;
+       unsigned char locked;
+
+       err = 0;
+       locked = !!si_noflush_read_trylock(sb);
+       bindex = au_br_index(sb, hinode->hi_id);
+       if (bindex >= 0)
+               err = au_xino_write0(sb, bindex, hinode->hi_inode->i_ino, ino);
+       /* error action? */
+       if (locked)
+               si_read_unlock(sb);
+       return err;
+}
+
+void au_iinfo_fin(struct inode *inode)
+{
+       ino_t ino;
+       aufs_bindex_t bend;
+       unsigned char unlinked = !inode->i_nlink || IS_DEADDIR(inode);
+       struct au_iinfo *iinfo;
+       struct au_hinode *hi;
+       struct super_block *sb;
+
+       if (unlinked) {
+               int err = au_xigen_inc(inode);
+               if (unlikely(err))
+                       AuWarn1("failed resetting i_generation, %d\n", err);
+       }
+
+       iinfo = au_ii(inode);
+       /* bad_inode case */
+       if (!iinfo)
+               return;
+
+       if (iinfo->ii_vdir)
+               au_vdir_free(iinfo->ii_vdir);
+
+       if (iinfo->ii_bstart >= 0) {
+               sb = inode->i_sb;
+               ino = 0;
+               if (unlinked)
+                       ino = inode->i_ino;
+               hi = iinfo->ii_hinode + iinfo->ii_bstart;
+               bend = iinfo->ii_bend;
+               while (iinfo->ii_bstart++ <= bend) {
+                       if (hi->hi_inode) {
+                               if (unlinked || !hi->hi_inode->i_nlink) {
+                                       au_iinfo_write0(sb, hi, ino);
+                                       /* ignore this error */
+                                       ino = 0;
+                               }
+                               au_hiput(hi);
+                       }
+                       hi++;
+               }
+       }
+
+       kfree(iinfo->ii_hinode);
+       au_rwsem_destroy(&iinfo->ii_rwsem);
+}
diff --git a/fs/aufs/inode.c b/fs/aufs/inode.c
new file mode 100644
index 0000000..c4a962b
--- /dev/null
+++ b/fs/aufs/inode.c
@@ -0,0 +1,356 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode functions
+ */
+
+#include "aufs.h"
+
+static void au_refresh_hinode_attr(struct inode *inode, int do_version)
+{
+       au_cpup_attr_all(inode, /*force*/0);
+       au_update_iigen(inode);
+       if (do_version)
+               inode->i_version++;
+}
+
+int au_refresh_hinode_self(struct inode *inode, int do_attr)
+{
+       int err;
+       aufs_bindex_t bindex, new_bindex;
+       unsigned char update;
+       struct inode *first;
+       struct au_hinode *p, *q, tmp;
+       struct super_block *sb;
+       struct au_iinfo *iinfo;
+
+       update = 0;
+       sb = inode->i_sb;
+       iinfo = au_ii(inode);
+       err = au_ii_realloc(iinfo, au_sbend(sb) + 1);
+       if (unlikely(err))
+               goto out;
+
+       p = iinfo->ii_hinode + iinfo->ii_bstart;
+       first = p->hi_inode;
+       err = 0;
+       for (bindex = iinfo->ii_bstart; bindex <= iinfo->ii_bend;
+            bindex++, p++) {
+               if (!p->hi_inode)
+                       continue;
+
+               new_bindex = au_br_index(sb, p->hi_id);
+               if (new_bindex == bindex)
+                       continue;
+
+               if (new_bindex < 0) {
+                       update++;
+                       au_hiput(p);
+                       p->hi_inode = NULL;
+                       continue;
+               }
+
+               if (new_bindex < iinfo->ii_bstart)
+                       iinfo->ii_bstart = new_bindex;
+               if (iinfo->ii_bend < new_bindex)
+                       iinfo->ii_bend = new_bindex;
+               /* swap two lower inode, and loop again */
+               q = iinfo->ii_hinode + new_bindex;
+               tmp = *q;
+               *q = *p;
+               *p = tmp;
+               if (tmp.hi_inode) {
+                       bindex--;
+                       p--;
+               }
+       }
+       au_update_brange(inode, /*do_put_zero*/0);
+       if (do_attr)
+               au_refresh_hinode_attr(inode, update && S_ISDIR(inode->i_mode));
+
+ out:
+       return err;
+}
+
+int au_refresh_hinode(struct inode *inode, struct dentry *dentry)
+{
+       int err, update;
+       unsigned int flags;
+       aufs_bindex_t bindex, bend;
+       unsigned char isdir;
+       struct inode *first;
+       struct au_hinode *p;
+       struct au_iinfo *iinfo;
+
+       err = au_refresh_hinode_self(inode, /*do_attr*/0);
+       if (unlikely(err))
+               goto out;
+
+       update = 0;
+       iinfo = au_ii(inode);
+       p = iinfo->ii_hinode + iinfo->ii_bstart;
+       first = p->hi_inode;
+       isdir = S_ISDIR(inode->i_mode);
+       flags = au_hi_flags(inode, isdir);
+       bend = au_dbend(dentry);
+       for (bindex = au_dbstart(dentry); bindex <= bend; bindex++) {
+               struct inode *h_i;
+               struct dentry *h_d;
+
+               h_d = au_h_dptr(dentry, bindex);
+               if (!h_d || !h_d->d_inode)
+                       continue;
+
+               if (iinfo->ii_bstart <= bindex && bindex <= iinfo->ii_bend) {
+                       h_i = au_h_iptr(inode, bindex);
+                       if (h_i) {
+                               if (h_i == h_d->d_inode)
+                                       continue;
+                               err = -EIO;
+                               break;
+                       }
+               }
+               if (bindex < iinfo->ii_bstart)
+                       iinfo->ii_bstart = bindex;
+               if (iinfo->ii_bend < bindex)
+                       iinfo->ii_bend = bindex;
+               au_set_h_iptr(inode, bindex, au_igrab(h_d->d_inode), flags);
+               update = 1;
+       }
+       au_update_brange(inode, /*do_put_zero*/0);
+
+       if (unlikely(err))
+               goto out;
+
+       au_refresh_hinode_attr(inode, update && isdir);
+
+ out:
+       return err;
+}
+
+static int set_inode(struct inode *inode, struct dentry *dentry)
+{
+       int err;
+       unsigned int flags;
+       umode_t mode;
+       aufs_bindex_t bindex, bstart, btail;
+       unsigned char isdir;
+       struct dentry *h_dentry;
+       struct inode *h_inode;
+       struct au_iinfo *iinfo;
+
+       err = 0;
+       isdir = 0;
+       bstart = au_dbstart(dentry);
+       h_inode = au_h_dptr(dentry, bstart)->d_inode;
+       mode = h_inode->i_mode;
+       switch (mode & S_IFMT) {
+       case S_IFREG:
+               btail = au_dbtail(dentry);
+               inode->i_op = &aufs_iop;
+               inode->i_fop = &aufs_file_fop;
+               inode->i_mapping->a_ops = &aufs_aop;
+               break;
+       case S_IFDIR:
+               isdir = 1;
+               btail = au_dbtaildir(dentry);
+               inode->i_op = &aufs_dir_iop;
+               inode->i_fop = &aufs_dir_fop;
+               break;
+       case S_IFLNK:
+               btail = au_dbtail(dentry);
+               inode->i_op = &aufs_symlink_iop;
+               break;
+       case S_IFBLK:
+       case S_IFCHR:
+       case S_IFIFO:
+       case S_IFSOCK:
+               btail = au_dbtail(dentry);
+               inode->i_op = &aufs_iop;
+               init_special_inode(inode, mode, h_inode->i_rdev);
+               break;
+       default:
+               AuIOErr("Unknown file type 0%o\n", mode);
+               err = -EIO;
+               goto out;
+       }
+
+       flags = au_hi_flags(inode, isdir);
+       iinfo = au_ii(inode);
+       iinfo->ii_bstart = bstart;
+       iinfo->ii_bend = btail;
+       for (bindex = bstart; bindex <= btail; bindex++) {
+               h_dentry = au_h_dptr(dentry, bindex);
+               if (h_dentry)
+                       au_set_h_iptr(inode, bindex,
+                                     au_igrab(h_dentry->d_inode), flags);
+       }
+       au_cpup_attr_all(inode, /*force*/1);
+
+ out:
+       return err;
+}
+
+/* successful returns with iinfo write_locked */
+static int reval_inode(struct inode *inode, struct dentry *dentry, int *matched)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       struct inode *h_inode, *h_dinode;
+
+       *matched = 0;
+
+       /*
+        * before this function, if aufs got any iinfo lock, it must be only
+        * one, the parent dir.
+        * it can happen by UDBA and the obsoleted inode number.
+        */
+       err = -EIO;
+       if (unlikely(inode->i_ino == parent_ino(dentry)))
+               goto out;
+
+       ii_write_lock_new_child(inode);
+       if (unlikely(IS_DEADDIR(inode)))
+               goto out_unlock;
+
+       err = 0;
+       h_dinode = au_h_dptr(dentry, au_dbstart(dentry))->d_inode;
+       bend = au_ibend(inode);
+       for (bindex = au_ibstart(inode); bindex <= bend; bindex++) {
+               h_inode = au_h_iptr(inode, bindex);
+               if (h_inode && h_inode == h_dinode) {
+                       *matched = 1;
+                       err = 0;
+                       if (au_iigen(inode) != au_digen(dentry))
+                               err = au_refresh_hinode(inode, dentry);
+                       break;
+               }
+       }
+
+ out_unlock:
+       if (unlikely(err))
+               ii_write_unlock(inode);
+ out:
+       return err;
+}
+
+/* successful returns with iinfo write_locked */
+/* todo: return with unlocked? */
+struct inode *au_new_inode(struct dentry *dentry, int must_new)
+{
+       struct inode *inode;
+       struct dentry *h_dentry;
+       struct super_block *sb;
+       ino_t h_ino, ino;
+       int err, match;
+       aufs_bindex_t bstart;
+
+       sb = dentry->d_sb;
+       bstart = au_dbstart(dentry);
+       h_dentry = au_h_dptr(dentry, bstart);
+       h_ino = h_dentry->d_inode->i_ino;
+       err = au_xino_read(sb, bstart, h_ino, &ino);
+       inode = ERR_PTR(err);
+       if (unlikely(err))
+               goto out;
+ new_ino:
+       if (!ino) {
+               ino = au_xino_new_ino(sb);
+               if (unlikely(!ino)) {
+                       inode = ERR_PTR(-EIO);
+                       goto out;
+               }
+       }
+
+       AuDbg("i%lu\n", (unsigned long)ino);
+       inode = au_iget_locked(sb, ino);
+       err = PTR_ERR(inode);
+       if (IS_ERR(inode))
+               goto out;
+
+       AuDbg("%lx, new %d\n", inode->i_state, !!(inode->i_state & I_NEW));
+       if (inode->i_state & I_NEW) {
+               ii_write_lock_new_child(inode);
+               err = set_inode(inode, dentry);
+               unlock_new_inode(inode);
+               if (!err)
+                       goto out; /* success */
+
+               iget_failed(inode);
+               ii_write_unlock(inode);
+               goto out_iput;
+       } else if (!must_new) {
+               err = reval_inode(inode, dentry, &match);
+               if (!err)
+                       goto out; /* success */
+               else if (match)
+                       goto out_iput;
+       }
+
+       if (unlikely(au_test_fs_unique_ino(h_dentry->d_inode)))
+               AuWarn1("Un-notified UDBA or repeatedly renamed dir,"
+                       " b%d, %s, %.*s, hi%lu, i%lu.\n",
+                       bstart, au_sbtype(h_dentry->d_sb), AuDLNPair(dentry),
+                       (unsigned long)h_ino, (unsigned long)ino);
+       ino = 0;
+       err = au_xino_write0(sb, bstart, h_ino, 0);
+       if (!err) {
+               iput(inode);
+               goto new_ino;
+       }
+
+ out_iput:
+       iput(inode);
+       inode = ERR_PTR(err);
+ out:
+       return inode;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_test_ro(struct super_block *sb, aufs_bindex_t bindex,
+              struct inode *inode)
+{
+       int err;
+
+       err = au_br_rdonly(au_sbr(sb, bindex));
+
+       /* pseudo-link after flushed may happen out of bounds */
+       if (!err
+           && inode
+           && au_ibstart(inode) <= bindex
+           && bindex <= au_ibend(inode)) {
+               /*
+                * permission check is unnecessary since vfsub routine
+                * will be called later
+                */
+               struct inode *hi = au_h_iptr(inode, bindex);
+               if (hi)
+                       err = IS_IMMUTABLE(hi) ? -EROFS : 0;
+       }
+
+       return err;
+}
+
+int au_test_h_perm(struct inode *h_inode, int mask)
+{
+       if (!current_fsuid())
+               return 0;
+       return inode_permission(h_inode, mask);
+}
+
+int au_test_h_perm_sio(struct inode *h_inode, int mask)
+{
+       if (au_test_nfs(h_inode->i_sb)
+           && (mask & MAY_WRITE)
+           && S_ISDIR(h_inode->i_mode))
+               mask |= MAY_READ; /* force permission check */
+       return au_test_h_perm(h_inode, mask);
+}
diff --git a/fs/aufs/inode.h b/fs/aufs/inode.h
new file mode 100644
index 0000000..ffda951
--- /dev/null
+++ b/fs/aufs/inode.h
@@ -0,0 +1,471 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * inode operations
+ */
+
+#ifndef __AUFS_INODE_H__
+#define __AUFS_INODE_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/inotify.h>
+#include <linux/namei.h>
+#include <linux/aufs_type.h>
+#include "rwsem.h"
+
+struct au_hinotify {
+#ifdef CONFIG_AUFS_HINOTIFY
+       struct inotify_watch    hin_watch;
+       struct inode            *hin_aufs_inode;        /* no get/put */
+#endif
+};
+
+struct au_hinode {
+       struct inode            *hi_inode;
+       aufs_bindex_t           hi_id;
+#ifdef CONFIG_AUFS_HINOTIFY
+       struct au_hinotify      *hi_notify;
+#endif
+
+       /* reference to the copied-up whiteout with get/put */
+       struct dentry           *hi_whdentry;
+};
+
+struct au_vdir;
+struct au_iinfo {
+       atomic_t                ii_generation;
+       struct super_block      *ii_hsb1;       /* no get/put */
+
+       struct rw_semaphore     ii_rwsem;
+       aufs_bindex_t           ii_bstart, ii_bend;
+       __u32                   ii_higen;
+       struct au_hinode        *ii_hinode;
+       struct au_vdir          *ii_vdir;
+};
+
+struct au_icntnr {
+       struct au_iinfo iinfo;
+       struct inode vfs_inode;
+};
+
+/* au_pin flags */
+#define AuPin_DI_LOCKED                1
+#define AuPin_MNT_WRITE                (1 << 1)
+#define au_ftest_pin(flags, name)      ((flags) & AuPin_##name)
+#define au_fset_pin(flags, name)       { (flags) |= AuPin_##name; }
+#define au_fclr_pin(flags, name)       { (flags) &= ~AuPin_##name; }
+
+struct au_pin {
+       /* input */
+       struct dentry *dentry;
+       unsigned int udba;
+       unsigned char lsc_di, lsc_hi, flags;
+       aufs_bindex_t bindex;
+
+       /* output */
+       struct dentry *parent;
+       struct au_hinode *hdir;
+       struct vfsmount *h_mnt;
+};
+
+/* ---------------------------------------------------------------------- */
+
+static inline struct au_iinfo *au_ii(struct inode *inode)
+{
+       struct au_iinfo *iinfo;
+
+       iinfo = &(container_of(inode, struct au_icntnr, vfs_inode)->iinfo);
+       if (iinfo->ii_hinode)
+               return iinfo;
+       return NULL; /* debugging bad_inode case */
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* inode.c */
+int au_refresh_hinode_self(struct inode *inode, int do_attr);
+int au_refresh_hinode(struct inode *inode, struct dentry *dentry);
+struct inode *au_new_inode(struct dentry *dentry, int must_new);
+int au_test_ro(struct super_block *sb, aufs_bindex_t bindex,
+              struct inode *inode);
+int au_test_h_perm(struct inode *h_inode, int mask);
+int au_test_h_perm_sio(struct inode *h_inode, int mask);
+
+/* i_op.c */
+extern struct inode_operations aufs_iop, aufs_symlink_iop, aufs_dir_iop;
+
+/* au_wr_dir flags */
+#define AuWrDir_ADD_ENTRY      1
+#define AuWrDir_ISDIR          (1 << 1)
+#define au_ftest_wrdir(flags, name)    ((flags) & AuWrDir_##name)
+#define au_fset_wrdir(flags, name)     { (flags) |= AuWrDir_##name; }
+#define au_fclr_wrdir(flags, name)     { (flags) &= ~AuWrDir_##name; }
+
+struct au_wr_dir_args {
+       aufs_bindex_t force_btgt;
+       unsigned char flags;
+};
+int au_wr_dir(struct dentry *dentry, struct dentry *src_dentry,
+             struct au_wr_dir_args *args);
+
+struct dentry *au_pinned_h_parent(struct au_pin *pin);
+void au_pin_init(struct au_pin *pin, struct dentry *dentry,
+                aufs_bindex_t bindex, int lsc_di, int lsc_hi,
+                unsigned int udba, unsigned char flags);
+int au_pin(struct au_pin *pin, struct dentry *dentry, aufs_bindex_t bindex,
+          unsigned int udba, unsigned char flags) __must_check;
+int au_do_pin(struct au_pin *pin) __must_check;
+void au_unpin(struct au_pin *pin);
+
+/* i_op_add.c */
+int au_may_add(struct dentry *dentry, aufs_bindex_t bindex,
+              struct dentry *h_parent, int isdir);
+int aufs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev);
+int aufs_symlink(struct inode *dir, struct dentry *dentry, const char *symname);
+int aufs_create(struct inode *dir, struct dentry *dentry, int mode,
+               struct nameidata *nd);
+int aufs_link(struct dentry *src_dentry, struct inode *dir,
+             struct dentry *dentry);
+int aufs_mkdir(struct inode *dir, struct dentry *dentry, int mode);
+
+/* i_op_del.c */
+int au_wr_dir_need_wh(struct dentry *dentry, int isdir, aufs_bindex_t *bcpup);
+int au_may_del(struct dentry *dentry, aufs_bindex_t bindex,
+              struct dentry *h_parent, int isdir);
+int aufs_unlink(struct inode *dir, struct dentry *dentry);
+int aufs_rmdir(struct inode *dir, struct dentry *dentry);
+
+/* i_op_ren.c */
+int au_wbr(struct dentry *dentry, aufs_bindex_t btgt);
+int aufs_rename(struct inode *src_dir, struct dentry *src_dentry,
+               struct inode *dir, struct dentry *dentry);
+
+/* iinfo.c */
+struct inode *au_h_iptr(struct inode *inode, aufs_bindex_t bindex);
+void au_hiput(struct au_hinode *hinode);
+void au_set_ibstart(struct inode *inode, aufs_bindex_t bindex);
+void au_set_hi_wh(struct inode *inode, aufs_bindex_t bindex,
+                 struct dentry *h_wh);
+unsigned int au_hi_flags(struct inode *inode, int isdir);
+
+/* hinode flags */
+#define AuHi_XINO      1
+#define AuHi_HINOTIFY  (1 << 1)
+#define au_ftest_hi(flags, name)       ((flags) & AuHi_##name)
+#define au_fset_hi(flags, name)                { (flags) |= AuHi_##name; }
+#define au_fclr_hi(flags, name)                { (flags) &= ~AuHi_##name; }
+
+#ifndef CONFIG_AUFS_HINOTIFY
+#undef AuHi_HINOTIFY
+#define AuHi_HINOTIFY  0
+#endif
+
+void au_set_h_iptr(struct inode *inode, aufs_bindex_t bindex,
+                  struct inode *h_inode, unsigned int flags);
+
+void au_update_iigen(struct inode *inode);
+void au_update_brange(struct inode *inode, int do_put_zero);
+
+int au_iinfo_init(struct inode *inode);
+void au_iinfo_fin(struct inode *inode);
+int au_ii_realloc(struct au_iinfo *iinfo, int nbr);
+
+/* plink.c */
+void au_plink_block_maintain(struct super_block *sb);
+#ifdef CONFIG_AUFS_DEBUG
+void au_plink_list(struct super_block *sb);
+#else
+static inline void au_plink_list(struct super_block *sb)
+{
+       /* nothing */
+}
+#endif
+int au_plink_test(struct inode *inode);
+struct dentry *au_plink_lkup(struct inode *inode, aufs_bindex_t bindex);
+void au_plink_append(struct inode *inode, aufs_bindex_t bindex,
+                    struct dentry *h_dentry);
+void au_plink_put(struct super_block *sb);
+void au_plink_half_refresh(struct super_block *sb, aufs_bindex_t br_id);
+
+/* ---------------------------------------------------------------------- */
+
+/* lock subclass for iinfo */
+enum {
+       AuLsc_II_CHILD,         /* child first */
+       AuLsc_II_CHILD2,        /* rename(2), link(2), and cpup at hinotify */
+       AuLsc_II_CHILD3,        /* copyup dirs */
+       AuLsc_II_PARENT,        /* see AuLsc_I_PARENT in vfsub.h */
+       AuLsc_II_PARENT2,
+       AuLsc_II_PARENT3,       /* copyup dirs */
+       AuLsc_II_NEW_CHILD
+};
+
+/*
+ * ii_read_lock_child, ii_write_lock_child,
+ * ii_read_lock_child2, ii_write_lock_child2,
+ * ii_read_lock_child3, ii_write_lock_child3,
+ * ii_read_lock_parent, ii_write_lock_parent,
+ * ii_read_lock_parent2, ii_write_lock_parent2,
+ * ii_read_lock_parent3, ii_write_lock_parent3,
+ * ii_read_lock_new_child, ii_write_lock_new_child,
+ */
+#define AuReadLockFunc(name, lsc) \
+static inline void ii_read_lock_##name(struct inode *i) \
+{ \
+       down_read_nested(&au_ii(i)->ii_rwsem, AuLsc_II_##lsc); \
+}
+
+#define AuWriteLockFunc(name, lsc) \
+static inline void ii_write_lock_##name(struct inode *i) \
+{ \
+       down_write_nested(&au_ii(i)->ii_rwsem, AuLsc_II_##lsc); \
+}
+
+#define AuRWLockFuncs(name, lsc) \
+       AuReadLockFunc(name, lsc) \
+       AuWriteLockFunc(name, lsc)
+
+AuRWLockFuncs(child, CHILD);
+AuRWLockFuncs(child2, CHILD2);
+AuRWLockFuncs(child3, CHILD3);
+AuRWLockFuncs(parent, PARENT);
+AuRWLockFuncs(parent2, PARENT2);
+AuRWLockFuncs(parent3, PARENT3);
+AuRWLockFuncs(new_child, NEW_CHILD);
+
+#undef AuReadLockFunc
+#undef AuWriteLockFunc
+#undef AuRWLockFuncs
+
+/*
+ * ii_read_unlock, ii_write_unlock, ii_downgrade_lock
+ */
+AuSimpleUnlockRwsemFuncs(ii, struct inode *i, &au_ii(i)->ii_rwsem);
+
+#define IiMustNoWaiters(i)     AuRwMustNoWaiters(&au_ii(i)->ii_rwsem)
+
+/* ---------------------------------------------------------------------- */
+
+static inline unsigned int au_iigen(struct inode *inode)
+{
+       return atomic_read(&au_ii(inode)->ii_generation);
+}
+
+/* tiny test for inode number */
+/* tmpfs generation is too rough */
+static inline int au_test_higen(struct inode *inode, struct inode *h_inode)
+{
+       struct au_iinfo *iinfo;
+
+       iinfo = au_ii(inode);
+       return !(iinfo->ii_hsb1 == h_inode->i_sb
+                && iinfo->ii_higen == h_inode->i_generation);
+}
+
+static inline struct inode *au_igrab(struct inode *inode)
+{
+       if (inode) {
+               AuDebugOn(!atomic_read(&inode->i_count));
+               atomic_inc(&inode->i_count);
+       }
+       return inode;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static inline aufs_bindex_t au_ii_br_id(struct inode *inode,
+                                       aufs_bindex_t bindex)
+{
+       return au_ii(inode)->ii_hinode[0 + bindex].hi_id;
+}
+
+static inline aufs_bindex_t au_ibstart(struct inode *inode)
+{
+       return au_ii(inode)->ii_bstart;
+}
+
+static inline aufs_bindex_t au_ibend(struct inode *inode)
+{
+       return au_ii(inode)->ii_bend;
+}
+
+static inline struct au_vdir *au_ivdir(struct inode *inode)
+{
+       return au_ii(inode)->ii_vdir;
+}
+
+static inline struct dentry *au_hi_wh(struct inode *inode, aufs_bindex_t bindex)
+{
+       return au_ii(inode)->ii_hinode[0 + bindex].hi_whdentry;
+}
+
+static inline void au_set_ibend(struct inode *inode, aufs_bindex_t bindex)
+{
+       au_ii(inode)->ii_bend = bindex;
+}
+
+static inline void au_set_ivdir(struct inode *inode, struct au_vdir *vdir)
+{
+       au_ii(inode)->ii_vdir = vdir;
+}
+
+static inline struct au_hinode *au_hi(struct inode *inode, aufs_bindex_t bindex)
+{
+       return au_ii(inode)->ii_hinode + bindex;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static inline struct dentry *au_pinned_parent(struct au_pin *pin)
+{
+       if (pin)
+               return pin->parent;
+       return NULL;
+}
+
+static inline struct inode *au_pinned_h_dir(struct au_pin *pin)
+{
+       if (pin && pin->hdir)
+               return pin->hdir->hi_inode;
+       return NULL;
+}
+
+static inline struct au_hinode *au_pinned_hdir(struct au_pin *pin)
+{
+       if (pin)
+               return pin->hdir;
+       return NULL;
+}
+
+static inline void au_pin_set_dentry(struct au_pin *pin, struct dentry *dentry)
+{
+       if (pin)
+               pin->dentry = dentry;
+}
+
+static inline void au_pin_set_parent_lflag(struct au_pin *pin,
+                                          unsigned char lflag)
+{
+       if (pin) {
+               /* dirty macros require brackets */
+               if (lflag) {
+                       au_fset_pin(pin->flags, DI_LOCKED);
+               } else {
+                       au_fclr_pin(pin->flags, DI_LOCKED);
+               }
+       }
+}
+
+static inline void au_pin_set_parent(struct au_pin *pin, struct dentry *parent)
+{
+       if (pin) {
+               dput(pin->parent);
+               pin->parent = dget(parent);
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+#ifdef CONFIG_AUFS_HINOTIFY
+/* hinotify.c */
+int au_hin_alloc(struct au_hinode *hinode, struct inode *inode,
+                struct inode *h_inode);
+void au_hin_free(struct au_hinode *hinode);
+void au_hin_ctl(struct au_hinode *hinode, int do_set);
+void au_reset_hinotify(struct inode *inode, unsigned int flags);
+
+int __init au_hinotify_init(void);
+void au_hinotify_fin(void);
+
+static inline
+void au_hin_init(struct au_hinode *hinode, struct au_hinotify *val)
+{
+       hinode->hi_notify = val;
+}
+
+static inline void au_iigen_dec(struct inode *inode)
+{
+       atomic_dec(&au_ii(inode)->ii_generation);
+}
+
+#else
+static inline
+int au_hin_alloc(struct au_hinode *hinode __maybe_unused,
+                struct inode *inode __maybe_unused,
+                struct inode *h_inode __maybe_unused)
+{
+       return -EOPNOTSUPP;
+}
+
+static inline void au_hin_free(struct au_hinode *hinode __maybe_unused)
+{
+       /* nothing */
+}
+
+static inline void au_hin_ctl(struct au_hinode *hinode __maybe_unused,
+                             int do_set __maybe_unused)
+{
+       /* nothing */
+}
+
+static inline void au_reset_hinotify(struct inode *inode __maybe_unused,
+                                    unsigned int flags __maybe_unused)
+{
+       /* nothing */
+}
+
+static inline int au_hinotify_init(void)
+{
+       return 0;
+}
+
+#define au_hinotify_fin()      do {} while (0)
+
+static inline
+void au_hin_init(struct au_hinode *hinode __maybe_unused,
+                struct au_hinotify *val __maybe_unused)
+{
+       /* empty */
+}
+#endif /* CONFIG_AUFS_HINOTIFY */
+
+static inline void au_hin_suspend(struct au_hinode *hdir)
+{
+       au_hin_ctl(hdir, /*do_set*/0);
+}
+
+static inline void au_hin_resume(struct au_hinode *hdir)
+{
+       au_hin_ctl(hdir, /*do_set*/1);
+}
+
+static inline void au_hin_imtx_lock(struct au_hinode *hdir)
+{
+       mutex_lock(&hdir->hi_inode->i_mutex);
+       au_hin_suspend(hdir);
+}
+
+static inline void au_hin_imtx_lock_nested(struct au_hinode *hdir,
+                                          unsigned int sc __maybe_unused)
+{
+       mutex_lock_nested(&hdir->hi_inode->i_mutex, sc);
+       au_hin_suspend(hdir);
+}
+
+static inline void au_hin_imtx_unlock(struct au_hinode *hdir)
+{
+       au_hin_resume(hdir);
+       mutex_unlock(&hdir->hi_inode->i_mutex);
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_INODE_H__ */
diff --git a/fs/aufs/ioctl.c b/fs/aufs/ioctl.c
new file mode 100644
index 0000000..ff17d77
--- /dev/null
+++ b/fs/aufs/ioctl.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/uaccess.h>
+#include "aufs.h"
+
+long aufs_ioctl_dir(struct file *file, unsigned int cmd,
+                   unsigned long arg __maybe_unused)
+{
+       long err;
+       struct super_block *sb;
+       struct au_sbinfo *sbinfo;
+
+       err = -EACCES;
+       if (!capable(CAP_SYS_ADMIN))
+               goto out;
+
+       err = 0;
+       sb = file->f_dentry->d_sb;
+       sbinfo = au_sbi(sb);
+       switch (cmd) {
+       case AUFS_CTL_PLINK_MAINT:
+               /*
+                * pseudo-link maintenance mode,
+                * cleared by aufs_release_dir()
+                */
+               si_write_lock(sb);
+               if (!au_ftest_si(sbinfo, MAINTAIN_PLINK)) {
+                       au_fset_si(sbinfo, MAINTAIN_PLINK);
+                       au_fi(file)->fi_maintain_plink = 1;
+               } else
+                       err = -EBUSY;
+               si_write_unlock(sb);
+               break;
+       case AUFS_CTL_PLINK_CLEAN:
+               if (au_opt_test(sbinfo->si_mntflags, PLINK)) {
+                       aufs_write_lock(sb->s_root);
+                       au_plink_put(sb);
+                       aufs_write_unlock(sb->s_root);
+               }
+               break;
+       default:
+               err = -EINVAL;
+       }
+
+ out:
+       return err;
+}
diff --git a/fs/aufs/loop.c b/fs/aufs/loop.c
new file mode 100644
index 0000000..84a940f
--- /dev/null
+++ b/fs/aufs/loop.c
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * support for loopback block device as a branch
+ */
+
+#include <linux/loop.h>
+#include "aufs.h"
+
+/*
+ * test if two lower dentries have overlapping branches.
+ */
+int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_d1,
+                            struct dentry *h_d2)
+{
+       struct inode *h_inode;
+       struct loop_device *l;
+
+       h_inode = h_d1->d_inode;
+       if (MAJOR(h_inode->i_sb->s_dev) != LOOP_MAJOR)
+               return 0;
+
+       l = h_inode->i_sb->s_bdev->bd_disk->private_data;
+       h_d1 = l->lo_backing_file->f_dentry;
+       /* h_d1 can be local NFS. in this case aufs cannot detect the loop */
+       if (unlikely(h_d1->d_sb == sb))
+               return 1;
+       return !!au_test_subdir(h_d1, h_d2);
+}
+
+/* true if a kernel thread named 'loop[0-9].*' accesses a file */
+int au_test_loopback_kthread(void)
+{
+       const char c = current->comm[4];
+
+       return current->mm == NULL
+              && '0' <= c && c <= '9'
+              && strncmp(current->comm, "loop", 4) == 0;
+}
diff --git a/fs/aufs/loop.h b/fs/aufs/loop.h
new file mode 100644
index 0000000..1c0ee40
--- /dev/null
+++ b/fs/aufs/loop.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * support for loopback mount as a branch
+ */
+
+#ifndef __AUFS_LOOP_H__
+#define __AUFS_LOOP_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+
+#ifdef CONFIG_AUFS_BDEV_LOOP
+/* loop.c */
+int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_d1,
+                            struct dentry *h_d2);
+int au_test_loopback_kthread(void);
+#else
+static inline
+int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_d1,
+                            struct dentry *h_d2)
+{
+       return 0;
+}
+
+static inline int au_test_loopback_kthread(void)
+{
+       return 0;
+}
+#endif /* BLK_DEV_LOOP */
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_LOOP_H__ */
diff --git a/fs/aufs/magic.mk b/fs/aufs/magic.mk
new file mode 100644
index 0000000..6258f57
--- /dev/null
+++ b/fs/aufs/magic.mk
@@ -0,0 +1,58 @@
+
+# defined in ${srctree}/fs/fuse/inode.c
+# tristate
+ifdef CONFIG_FUSE_FS
+ccflags-y += -DFUSE_SUPER_MAGIC=0x65735546
+endif
+
+# defined in ${srctree}/fs/ocfs2/ocfs2_fs.h
+# tristate
+ifdef CONFIG_OCFS2_FS
+ccflags-y += -DOCFS2_SUPER_MAGIC=0x7461636f
+endif
+
+# defined in ${srctree}/fs/ocfs2/dlm/userdlm.h
+# tristate
+ifdef CONFIG_OCFS2_FS_O2CB
+ccflags-y += -DDLMFS_MAGIC=0x76a9f425
+endif
+
+# defined in ${srctree}/fs/ramfs/inode.c
+# always true
+ccflags-y += -DRAMFS_MAGIC=0x858458f6
+
+# defined in ${srctree}/fs/cifs/cifsfs.c
+# tristate
+ifdef CONFIG_CIFS_FS
+ccflags-y += -DCIFS_MAGIC_NUMBER=0xFF534D42
+endif
+
+# defined in ${srctree}/fs/xfs/xfs_sb.h
+# tristate
+ifdef CONFIG_XFS_FS
+ccflags-y += -DXFS_SB_MAGIC=0x58465342
+endif
+
+# defined in ${srctree}/fs/configfs/mount.c
+# tristate
+ifdef CONFIG_CONFIGFS_FS
+ccflags-y += -DCONFIGFS_MAGIC=0x62656570
+endif
+
+# defined in ${srctree}/fs/9p/v9fs.h
+# tristate
+ifdef CONFIG_9P_FS
+ccflags-y += -DV9FS_MAGIC=0x01021997
+endif
+
+# defined in ${srctree}/fs/ubifs/ubifs.h
+# tristate
+ifdef CONFIG_UBIFS_FS
+ccflags-y += -DUBIFS_SUPER_MAGIC=0x24051905
+endif
+
+# defined in ${srctree}/fs/debugfs/inode.c
+# boolean
+ifdef CONFIG_DEBUG_FS
+ccflags-y += -DDEBUGFS_MAGIC=0x64626720
+endif
diff --git a/fs/aufs/module.c b/fs/aufs/module.c
new file mode 100644
index 0000000..c2219d3
--- /dev/null
+++ b/fs/aufs/module.c
@@ -0,0 +1,164 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * module global variables and operations
+ */
+
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include "aufs.h"
+
+void *au_kzrealloc(void *p, unsigned int nused, unsigned int new_sz, gfp_t gfp)
+{
+       if (new_sz <= nused)
+               return p;
+
+       p = krealloc(p, new_sz, gfp);
+       if (p)
+               memset(p + nused, 0, new_sz - nused);
+       return p;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * aufs caches
+ */
+struct kmem_cache *au_cachep[AuCache_Last];
+static int __init au_cache_init(void)
+{
+       au_cachep[AuCache_DINFO] = AuCache(au_dinfo);
+       if (au_cachep[AuCache_DINFO])
+               au_cachep[AuCache_ICNTNR] = AuCache(au_icntnr);
+       if (au_cachep[AuCache_ICNTNR])
+               au_cachep[AuCache_FINFO] = AuCache(au_finfo);
+       if (au_cachep[AuCache_FINFO])
+               au_cachep[AuCache_VDIR] = AuCache(au_vdir);
+       if (au_cachep[AuCache_VDIR])
+               au_cachep[AuCache_DEHSTR] = AuCache(au_vdir_dehstr);
+       if (au_cachep[AuCache_DEHSTR])
+               return 0;
+
+       return -ENOMEM;
+}
+
+static void au_cache_fin(void)
+{
+       int i;
+       for (i = 0; i < AuCache_Last; i++)
+               if (au_cachep[i]) {
+                       kmem_cache_destroy(au_cachep[i]);
+                       au_cachep[i] = NULL;
+               }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_dir_roflags;
+
+/*
+ * functions for module interface.
+ */
+MODULE_LICENSE("GPL");
+/* MODULE_LICENSE("GPL v2"); */
+MODULE_AUTHOR("Junjiro R. Okajima");
+MODULE_DESCRIPTION(AUFS_NAME
+       " -- Advanced multi layered unification filesystem");
+MODULE_VERSION(AUFS_VERSION);
+
+/* it should be 'byte', but param_set_byte() prints it by "%c" */
+short aufs_nwkq = AUFS_NWKQ_DEF;
+MODULE_PARM_DESC(nwkq, "the number of workqueue thread, " AUFS_WKQ_NAME);
+module_param_named(nwkq, aufs_nwkq, short, S_IRUGO);
+
+/* this module parameter has no meaning when SYSFS is disabled */
+int sysaufs_brs = 1;
+MODULE_PARM_DESC(brs, "use <sysfs>/fs/aufs/si_*/brN");
+module_param_named(brs, sysaufs_brs, int, S_IRUGO);
+
+/* ---------------------------------------------------------------------- */
+
+static char au_esc_chars[0x20 + 3]; /* 0x01-0x20, backslash, del, and NULL */
+
+int au_seq_path(struct seq_file *seq, struct path *path)
+{
+       return seq_path(seq, path, au_esc_chars);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int __init aufs_init(void)
+{
+       int err, i;
+       char *p;
+
+       p = au_esc_chars;
+       for (i = 1; i <= ' '; i++)
+               *p++ = i;
+       *p++ = '\\';
+       *p++ = '\x7f';
+       *p = 0;
+
+       au_dir_roflags = au_file_roflags(O_DIRECTORY | O_LARGEFILE);
+
+       sysaufs_brs_init();
+       au_debug_init();
+
+       err = -EINVAL;
+       if (unlikely(aufs_nwkq <= 0))
+               goto out;
+
+       err = sysaufs_init();
+       if (unlikely(err))
+               goto out;
+       err = au_wkq_init();
+       if (unlikely(err))
+               goto out_sysaufs;
+       err = au_hinotify_init();
+       if (unlikely(err))
+               goto out_wkq;
+       err = au_sysrq_init();
+       if (unlikely(err))
+               goto out_hin;
+       err = au_cache_init();
+       if (unlikely(err))
+               goto out_sysrq;
+       err = register_filesystem(&aufs_fs_type);
+       if (unlikely(err))
+               goto out_cache;
+       pr_info(AUFS_NAME " " AUFS_VERSION "\n");
+       goto out; /* success */
+
+ out_cache:
+       au_cache_fin();
+ out_sysrq:
+       au_sysrq_fin();
+ out_hin:
+       au_hinotify_fin();
+ out_wkq:
+       au_wkq_fin();
+ out_sysaufs:
+       sysaufs_fin();
+ out:
+       return err;
+}
+
+static void __exit aufs_exit(void)
+{
+       unregister_filesystem(&aufs_fs_type);
+       au_cache_fin();
+       au_sysrq_fin();
+       au_hinotify_fin();
+       au_wkq_fin();
+       sysaufs_fin();
+}
+
+module_init(aufs_init);
+module_exit(aufs_exit);
diff --git a/fs/aufs/module.h b/fs/aufs/module.h
new file mode 100644
index 0000000..85e397a
--- /dev/null
+++ b/fs/aufs/module.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * module initialization and module-global
+ */
+
+#ifndef __AUFS_MODULE_H__
+#define __AUFS_MODULE_H__
+
+#ifdef __KERNEL__
+
+#include <linux/slab.h>
+
+/* module parameters */
+extern short aufs_nwkq;
+extern int sysaufs_brs;
+
+/* ---------------------------------------------------------------------- */
+
+extern int au_dir_roflags;
+
+void *au_kzrealloc(void *p, unsigned int nused, unsigned int new_sz, gfp_t gfp);
+int au_seq_path(struct seq_file *seq, struct path *path);
+
+/* ---------------------------------------------------------------------- */
+
+/* kmem cache */
+enum {
+       AuCache_DINFO,
+       AuCache_ICNTNR,
+       AuCache_FINFO,
+       AuCache_VDIR,
+       AuCache_DEHSTR,
+#ifdef CONFIG_AUFS_HINOTIFY
+       AuCache_HINOTIFY,
+#endif
+       AuCache_Last
+};
+
+#define AuCache(type)  KMEM_CACHE(type, SLAB_RECLAIM_ACCOUNT)
+
+extern struct kmem_cache *au_cachep[];
+
+#define AuCacheFuncs(name, index) \
+static inline void *au_cache_alloc_##name(void) \
+{ return kmem_cache_alloc(au_cachep[AuCache_##index], GFP_NOFS); } \
+static inline void au_cache_free_##name(void *p) \
+{ kmem_cache_free(au_cachep[AuCache_##index], p); }
+
+AuCacheFuncs(dinfo, DINFO);
+AuCacheFuncs(icntnr, ICNTNR);
+AuCacheFuncs(finfo, FINFO);
+AuCacheFuncs(vdir, VDIR);
+AuCacheFuncs(dehstr, DEHSTR);
+
+/*  ---------------------------------------------------------------------- */
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_MODULE_H__ */
diff --git a/fs/aufs/opts.c b/fs/aufs/opts.c
new file mode 100644
index 0000000..630db0e
--- /dev/null
+++ b/fs/aufs/opts.c
@@ -0,0 +1,1478 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * mount options/flags
+ */
+
+#include <linux/types.h> /* a distribution requires */
+#include <linux/parser.h>
+#include "aufs.h"
+
+/* ---------------------------------------------------------------------- */
+
+enum {
+       Opt_br,
+       Opt_add, Opt_del, Opt_mod, Opt_reorder, Opt_append, Opt_prepend,
+       Opt_idel, Opt_imod, Opt_ireorder,
+       Opt_dirwh, Opt_rdcache, Opt_rdblk, Opt_rdhash, Opt_rendir,
+       Opt_xino, Opt_zxino, Opt_noxino,
+       Opt_trunc_xino, Opt_trunc_xino_v, Opt_notrunc_xino,
+       Opt_trunc_xino_path, Opt_itrunc_xino,
+       Opt_trunc_xib, Opt_notrunc_xib,
+       Opt_plink, Opt_noplink, Opt_list_plink,
+       Opt_udba,
+       /* Opt_lock, Opt_unlock, */
+       Opt_cmd, Opt_cmd_args,
+       Opt_diropq_a, Opt_diropq_w,
+       Opt_warn_perm, Opt_nowarn_perm,
+       Opt_wbr_copyup, Opt_wbr_create,
+       Opt_refrof, Opt_norefrof,
+       Opt_verbose, Opt_noverbose,
+       Opt_sum, Opt_nosum, Opt_wsum,
+       Opt_tail, Opt_ignore, Opt_ignore_silent, Opt_err
+};
+
+static match_table_t options = {
+       {Opt_br, "br=%s"},
+       {Opt_br, "br:%s"},
+
+       {Opt_add, "add=%d:%s"},
+       {Opt_add, "add:%d:%s"},
+       {Opt_add, "ins=%d:%s"},
+       {Opt_add, "ins:%d:%s"},
+       {Opt_append, "append=%s"},
+       {Opt_append, "append:%s"},
+       {Opt_prepend, "prepend=%s"},
+       {Opt_prepend, "prepend:%s"},
+
+       {Opt_del, "del=%s"},
+       {Opt_del, "del:%s"},
+       /* {Opt_idel, "idel:%d"}, */
+       {Opt_mod, "mod=%s"},
+       {Opt_mod, "mod:%s"},
+       /* {Opt_imod, "imod:%d:%s"}, */
+
+       {Opt_dirwh, "dirwh=%d"},
+
+       {Opt_xino, "xino=%s"},
+       {Opt_noxino, "noxino"},
+       {Opt_trunc_xino, "trunc_xino"},
+       {Opt_trunc_xino_v, "trunc_xino_v=%d:%d"},
+       {Opt_notrunc_xino, "notrunc_xino"},
+       {Opt_trunc_xino_path, "trunc_xino=%s"},
+       {Opt_itrunc_xino, "itrunc_xino=%d"},
+       /* {Opt_zxino, "zxino=%s"}, */
+       {Opt_trunc_xib, "trunc_xib"},
+       {Opt_notrunc_xib, "notrunc_xib"},
+
+       {Opt_plink, "plink"},
+       {Opt_noplink, "noplink"},
+#ifdef CONFIG_AUFS_DEBUG
+       {Opt_list_plink, "list_plink"},
+#endif
+
+       {Opt_udba, "udba=%s"},
+
+       {Opt_diropq_a, "diropq=always"},
+       {Opt_diropq_a, "diropq=a"},
+       {Opt_diropq_w, "diropq=whiteouted"},
+       {Opt_diropq_w, "diropq=w"},
+
+       {Opt_warn_perm, "warn_perm"},
+       {Opt_nowarn_perm, "nowarn_perm"},
+
+       /* keep them temporary */
+       {Opt_ignore_silent, "coo=%s"},
+       {Opt_ignore_silent, "nodlgt"},
+       {Opt_ignore_silent, "nodirperm1"},
+       {Opt_ignore_silent, "noshwh"},
+       {Opt_ignore_silent, "clean_plink"},
+
+       {Opt_rendir, "rendir=%d"},
+
+       {Opt_refrof, "refrof"},
+       {Opt_norefrof, "norefrof"},
+
+       {Opt_verbose, "verbose"},
+       {Opt_verbose, "v"},
+       {Opt_noverbose, "noverbose"},
+       {Opt_noverbose, "quiet"},
+       {Opt_noverbose, "q"},
+       {Opt_noverbose, "silent"},
+
+       {Opt_sum, "sum"},
+       {Opt_nosum, "nosum"},
+       {Opt_wsum, "wsum"},
+
+       {Opt_rdcache, "rdcache=%d"},
+       {Opt_rdblk, "rdblk=%d"},
+       {Opt_rdhash, "rdhash=%d"},
+
+       {Opt_wbr_create, "create=%s"},
+       {Opt_wbr_create, "create_policy=%s"},
+       {Opt_wbr_copyup, "cpup=%s"},
+       {Opt_wbr_copyup, "copyup=%s"},
+       {Opt_wbr_copyup, "copyup_policy=%s"},
+
+       /* internal use for the scripts */
+       {Opt_ignore_silent, "si=%s"},
+
+       {Opt_br, "dirs=%s"},
+       {Opt_ignore, "debug=%d"},
+       {Opt_ignore, "delete=whiteout"},
+       {Opt_ignore, "delete=all"},
+       {Opt_ignore, "imap=%s"},
+
+       {Opt_err, NULL}
+};
+
+/* ---------------------------------------------------------------------- */
+
+static const char *au_parser_pattern(int val, struct match_token *token)
+{
+       while (token->pattern) {
+               if (token->token == val)
+                       return token->pattern;
+               token++;
+       }
+       BUG();
+       return "??";
+}
+
+/* ---------------------------------------------------------------------- */
+
+static match_table_t brperms = {
+       {AuBrPerm_RO, AUFS_BRPERM_RO},
+       {AuBrPerm_RR, AUFS_BRPERM_RR},
+       {AuBrPerm_RW, AUFS_BRPERM_RW},
+
+       {AuBrPerm_ROWH, AUFS_BRPERM_ROWH},
+       {AuBrPerm_RRWH, AUFS_BRPERM_RRWH},
+       {AuBrPerm_RWNoLinkWH, AUFS_BRPERM_RWNLWH},
+
+       {AuBrPerm_ROWH, "nfsro"},
+       {AuBrPerm_RO, NULL}
+};
+
+static int br_perm_val(char *perm)
+{
+       int val;
+       substring_t args[MAX_OPT_ARGS];
+
+       val = match_token(perm, brperms, args);
+       return val;
+}
+
+const char *au_optstr_br_perm(int brperm)
+{
+       return au_parser_pattern(brperm, (void *)brperms);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static match_table_t udbalevel = {
+       {AuOpt_UDBA_REVAL, "reval"},
+       {AuOpt_UDBA_NONE, "none"},
+#ifdef CONFIG_AUFS_HINOTIFY
+       {AuOpt_UDBA_HINOTIFY, "inotify"},
+#endif
+       {-1, NULL}
+};
+
+static int udba_val(char *str)
+{
+       substring_t args[MAX_OPT_ARGS];
+
+       return match_token(str, udbalevel, args);
+}
+
+const char *au_optstr_udba(int udba)
+{
+       return au_parser_pattern(udba, (void *)udbalevel);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static match_table_t au_wbr_create_policy = {
+       {AuWbrCreate_TDP, "tdp"},
+       {AuWbrCreate_TDP, "top-down-parent"},
+       {AuWbrCreate_RR, "rr"},
+       {AuWbrCreate_RR, "round-robin"},
+       {AuWbrCreate_MFS, "mfs"},
+       {AuWbrCreate_MFS, "most-free-space"},
+       {AuWbrCreate_MFSV, "mfs:%d"},
+       {AuWbrCreate_MFSV, "most-free-space:%d"},
+
+       {AuWbrCreate_MFSRR, "mfsrr:%d"},
+       {AuWbrCreate_MFSRRV, "mfsrr:%d:%d"},
+       {AuWbrCreate_PMFS, "pmfs"},
+       {AuWbrCreate_PMFSV, "pmfs:%d"},
+
+       {-1, NULL}
+};
+
+/* cf. linux/lib/parser.c */
+static int au_match_ull(substring_t *s, unsigned long long *result)
+{
+       int err;
+       unsigned int len;
+       char a[32];
+
+       err = -ERANGE;
+       len = s->to - s->from;
+       if (len + 1 <= sizeof(a)) {
+               memcpy(a, s->from, len);
+               a[len] = '\0';
+               err = strict_strtoull(a, 0, result);
+       }
+       return err;
+}
+
+static int au_wbr_mfs_wmark(substring_t *arg, char *str,
+                           struct au_opt_wbr_create *create)
+{
+       int err;
+       unsigned long long ull;
+
+       err = 0;
+       if (!au_match_ull(arg, &ull))
+               create->mfsrr_watermark = ull;
+       else {
+               AuErr("bad integer in %s\n", str);
+               err = -EINVAL;
+       }
+
+       return err;
+}
+
+static int au_wbr_mfs_sec(substring_t *arg, char *str,
+                         struct au_opt_wbr_create *create)
+{
+       int n, err;
+
+       err = 0;
+       if (!match_int(arg, &n) && 0 <= n)
+               create->mfs_second = n;
+       else {
+               AuErr("bad integer in %s\n", str);
+               err = -EINVAL;
+       }
+
+       return err;
+}
+
+static int au_wbr_create_val(char *str, struct au_opt_wbr_create *create)
+{
+       int err, e;
+       substring_t args[MAX_OPT_ARGS];
+
+       err = match_token(str, au_wbr_create_policy, args);
+       create->wbr_create = err;
+       switch (err) {
+       case AuWbrCreate_MFSRRV:
+               e = au_wbr_mfs_wmark(&args[0], str, create);
+               if (!e)
+                       e = au_wbr_mfs_sec(&args[1], str, create);
+               if (unlikely(e))
+                       err = e;
+               break;
+       case AuWbrCreate_MFSRR:
+               e = au_wbr_mfs_wmark(&args[0], str, create);
+               if (unlikely(e)) {
+                       err = e;
+                       break;
+               }
+               /*FALLTHROUGH*/
+       case AuWbrCreate_MFS:
+       case AuWbrCreate_PMFS:
+               create->mfs_second = AUFS_MFS_SECOND_DEF;
+               break;
+       case AuWbrCreate_MFSV:
+       case AuWbrCreate_PMFSV:
+               e = au_wbr_mfs_sec(&args[0], str, create);
+               if (unlikely(e))
+                       err = e;
+               break;
+       }
+
+       return err;
+}
+
+const char *au_optstr_wbr_create(int wbr_create)
+{
+       return au_parser_pattern(wbr_create, (void *)au_wbr_create_policy);
+}
+
+static match_table_t au_wbr_copyup_policy = {
+       {AuWbrCopyup_TDP, "tdp"},
+       {AuWbrCopyup_TDP, "top-down-parent"},
+       {AuWbrCopyup_BUP, "bup"},
+       {AuWbrCopyup_BUP, "bottom-up-parent"},
+       {AuWbrCopyup_BU, "bu"},
+       {AuWbrCopyup_BU, "bottom-up"},
+       {-1, NULL}
+};
+
+static int au_wbr_copyup_val(char *str)
+{
+       substring_t args[MAX_OPT_ARGS];
+
+       return match_token(str, au_wbr_copyup_policy, args);
+}
+
+const char *au_optstr_wbr_copyup(int wbr_copyup)
+{
+       return au_parser_pattern(wbr_copyup, (void *)au_wbr_copyup_policy);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static const int lkup_dirflags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+
+static void dump_opts(struct au_opts *opts)
+{
+#ifdef CONFIG_AUFS_DEBUG
+       /* reduce stack space */
+       union {
+               struct au_opt_add *add;
+               struct au_opt_del *del;
+               struct au_opt_mod *mod;
+               struct au_opt_xino *xino;
+               struct au_opt_xino_itrunc *xino_itrunc;
+               struct au_opt_wbr_create *create;
+       } u;
+       struct au_opt *opt;
+
+       opt = opts->opt;
+       while (opt->type != Opt_tail) {
+               switch (opt->type) {
+               case Opt_add:
+                       u.add = &opt->add;
+                       AuDbg("add {b%d, %s, 0x%x, %p}\n",
+                                 u.add->bindex, u.add->pathname, u.add->perm,
+                                 u.add->path.dentry);
+                       break;
+               case Opt_del:
+               case Opt_idel:
+                       u.del = &opt->del;
+                       AuDbg("del {%s, %p}\n",
+                             u.del->pathname, u.del->h_path.dentry);
+                       break;
+               case Opt_mod:
+               case Opt_imod:
+                       u.mod = &opt->mod;
+                       AuDbg("mod {%s, 0x%x, %p}\n",
+                                 u.mod->path, u.mod->perm, u.mod->h_root);
+                       break;
+               case Opt_append:
+                       u.add = &opt->add;
+                       AuDbg("append {b%d, %s, 0x%x, %p}\n",
+                                 u.add->bindex, u.add->pathname, u.add->perm,
+                                 u.add->path.dentry);
+                       break;
+               case Opt_prepend:
+                       u.add = &opt->add;
+                       AuDbg("prepend {b%d, %s, 0x%x, %p}\n",
+                                 u.add->bindex, u.add->pathname, u.add->perm,
+                                 u.add->path.dentry);
+                       break;
+               case Opt_dirwh:
+                       AuDbg("dirwh %d\n", opt->dirwh);
+                       break;
+               case Opt_rdcache:
+                       AuDbg("rdcache %d\n", opt->rdcache);
+                       break;
+               case Opt_rdblk:
+                       AuDbg("rdblk %u\n", opt->rdblk);
+                       break;
+               case Opt_rdhash:
+                       AuDbg("rdhash %u\n", opt->rdhash);
+                       break;
+               case Opt_xino:
+                       u.xino = &opt->xino;
+                       AuDbg("xino {%s %.*s}\n",
+                                 u.xino->path,
+                                 AuDLNPair(u.xino->file->f_dentry));
+                       break;
+               case Opt_trunc_xino:
+                       AuLabel(trunc_xino);
+                       break;
+               case Opt_notrunc_xino:
+                       AuLabel(notrunc_xino);
+                       break;
+               case Opt_trunc_xino_path:
+               case Opt_itrunc_xino:
+                       u.xino_itrunc = &opt->xino_itrunc;
+                       AuDbg("trunc_xino %d\n", u.xino_itrunc->bindex);
+                       break;
+
+               case Opt_noxino:
+                       AuLabel(noxino);
+                       break;
+               case Opt_trunc_xib:
+                       AuLabel(trunc_xib);
+                       break;
+               case Opt_notrunc_xib:
+                       AuLabel(notrunc_xib);
+                       break;
+               case Opt_plink:
+                       AuLabel(plink);
+                       break;
+               case Opt_noplink:
+                       AuLabel(noplink);
+                       break;
+               case Opt_list_plink:
+                       AuLabel(list_plink);
+                       break;
+               case Opt_udba:
+                       AuDbg("udba %d, %s\n",
+                                 opt->udba, au_optstr_udba(opt->udba));
+                       break;
+               case Opt_diropq_a:
+                       AuLabel(diropq_a);
+                       break;
+               case Opt_diropq_w:
+                       AuLabel(diropq_w);
+                       break;
+               case Opt_warn_perm:
+                       AuLabel(warn_perm);
+                       break;
+               case Opt_nowarn_perm:
+                       AuLabel(nowarn_perm);
+                       break;
+               case Opt_refrof:
+                       AuLabel(refrof);
+                       break;
+               case Opt_norefrof:
+                       AuLabel(norefrof);
+                       break;
+               case Opt_verbose:
+                       AuLabel(verbose);
+                       break;
+               case Opt_noverbose:
+                       AuLabel(noverbose);
+                       break;
+               case Opt_sum:
+                       AuLabel(sum);
+                       break;
+               case Opt_nosum:
+                       AuLabel(nosum);
+                       break;
+               case Opt_wsum:
+                       AuLabel(wsum);
+                       break;
+               case Opt_wbr_create:
+                       u.create = &opt->wbr_create;
+                       AuDbg("create %d, %s\n", u.create->wbr_create,
+                                 au_optstr_wbr_create(u.create->wbr_create));
+                       switch (u.create->wbr_create) {
+                       case AuWbrCreate_MFSV:
+                       case AuWbrCreate_PMFSV:
+                               AuDbg("%d sec\n", u.create->mfs_second);
+                               break;
+                       case AuWbrCreate_MFSRR:
+                               AuDbg("%llu watermark\n",
+                                         u.create->mfsrr_watermark);
+                               break;
+                       case AuWbrCreate_MFSRRV:
+                               AuDbg("%llu watermark, %d sec\n",
+                                         u.create->mfsrr_watermark,
+                                         u.create->mfs_second);
+                               break;
+                       }
+                       break;
+               case Opt_wbr_copyup:
+                       AuDbg("copyup %d, %s\n", opt->wbr_copyup,
+                                 au_optstr_wbr_copyup(opt->wbr_copyup));
+                       break;
+               default:
+                       BUG();
+               }
+               opt++;
+       }
+#endif
+}
+
+void au_opts_free(struct au_opts *opts)
+{
+       struct au_opt *opt;
+
+       opt = opts->opt;
+       while (opt->type != Opt_tail) {
+               switch (opt->type) {
+               case Opt_add:
+               case Opt_append:
+               case Opt_prepend:
+                       path_put(&opt->add.path);
+                       break;
+               case Opt_del:
+               case Opt_idel:
+                       path_put(&opt->del.h_path);
+                       break;
+               case Opt_mod:
+               case Opt_imod:
+                       dput(opt->mod.h_root);
+                       break;
+               case Opt_xino:
+                       fput(opt->xino.file);
+                       break;
+               }
+               opt++;
+       }
+}
+
+static int opt_add(struct au_opt *opt, char *opt_str, unsigned long sb_flags,
+                  aufs_bindex_t bindex)
+{
+       int err;
+       struct au_opt_add *add = &opt->add;
+       char *p;
+
+       add->bindex = bindex;
+       add->perm = AuBrPerm_Last;
+       add->pathname = opt_str;
+       p = strchr(opt_str, '=');
+       if (p) {
+               *p++ = 0;
+               if (*p)
+                       add->perm = br_perm_val(p);
+       }
+
+       err = vfsub_kern_path(add->pathname, lkup_dirflags, &add->path);
+       if (!err) {
+               if (!p) {
+                       add->perm = AuBrPerm_RO;
+                       if (au_test_fs_rr(add->path.dentry->d_sb))
+                               add->perm = AuBrPerm_RR;
+                       else if (!bindex && !(sb_flags & MS_RDONLY))
+                               add->perm = AuBrPerm_RW;
+               }
+               opt->type = Opt_add;
+               goto out;
+       }
+       AuErr("lookup failed %s (%d)\n", add->pathname, err);
+       err = -EINVAL;
+
+ out:
+       return err;
+}
+
+static int au_opts_parse_del(struct au_opt_del *del, substring_t args[])
+{
+       int err;
+
+       del->pathname = args[0].from;
+       AuDbg("del path %s\n", del->pathname);
+
+       err = vfsub_kern_path(del->pathname, lkup_dirflags, &del->h_path);
+       if (unlikely(err))
+               AuErr("lookup failed %s (%d)\n", del->pathname, err);
+
+       return err;
+}
+
+#if 0 /* reserved for future use */
+static int au_opts_parse_idel(struct super_block *sb, aufs_bindex_t bindex,
+                             struct au_opt_del *del, substring_t args[])
+{
+       int err;
+       struct dentry *root;
+
+       err = -EINVAL;
+       root = sb->s_root;
+       aufs_read_lock(root, AuLock_FLUSH);
+       if (bindex < 0 || au_sbend(sb) < bindex) {
+               AuErr("out of bounds, %d\n", bindex);
+               goto out;
+       }
+
+       err = 0;
+       del->h_path.dentry = dget(au_h_dptr(root, bindex));
+       del->h_path.mnt = mntget(au_sbr_mnt(sb, bindex));
+
+ out:
+       aufs_read_unlock(root, !AuLock_IR);
+       return err;
+}
+#endif
+
+static int au_opts_parse_mod(struct au_opt_mod *mod, substring_t args[])
+{
+       int err;
+       struct path path;
+       char *p;
+
+       err = -EINVAL;
+       mod->path = args[0].from;
+       p = strchr(mod->path, '=');
+       if (unlikely(!p)) {
+               AuErr("no permssion %s\n", args[0].from);
+               goto out;
+       }
+
+       *p++ = 0;
+       err = vfsub_kern_path(mod->path, lkup_dirflags, &path);
+       if (unlikely(err)) {
+               AuErr("lookup failed %s (%d)\n", mod->path, err);
+               goto out;
+       }
+
+       mod->perm = br_perm_val(p);
+       AuDbg("mod path %s, perm 0x%x, %s\n", mod->path, mod->perm, p);
+       mod->h_root = dget(path.dentry);
+       path_put(&path);
+
+ out:
+       return err;
+}
+
+#if 0 /* reserved for future use */
+static int au_opts_parse_imod(struct super_block *sb, aufs_bindex_t bindex,
+                             struct au_opt_mod *mod, substring_t args[])
+{
+       int err;
+       struct dentry *root;
+
+       err = -EINVAL;
+       root = sb->s_root;
+       aufs_read_lock(root, AuLock_FLUSH);
+       if (bindex < 0 || au_sbend(sb) < bindex) {
+               AuErr("out of bounds, %d\n", bindex);
+               goto out;
+       }
+
+       err = 0;
+       mod->perm = br_perm_val(args[1].from);
+       AuDbg("mod path %s, perm 0x%x, %s\n",
+             mod->path, mod->perm, args[1].from);
+       mod->h_root = dget(au_h_dptr(root, bindex));
+
+ out:
+       aufs_read_unlock(root, !AuLock_IR);
+       return err;
+}
+#endif
+
+static int au_opts_parse_xino(struct super_block *sb, struct au_opt_xino *xino,
+                             substring_t args[])
+{
+       int err;
+       struct file *file;
+
+       file = au_xino_create(sb, args[0].from, /*silent*/0);
+       err = PTR_ERR(file);
+       if (IS_ERR(file))
+               goto out;
+
+       err = -EINVAL;
+       if (unlikely(file->f_dentry->d_sb == sb)) {
+               fput(file);
+               AuErr("%s must be outside\n", args[0].from);
+               goto out;
+       }
+
+       err = 0;
+       xino->file = file;
+       xino->path = args[0].from;
+
+ out:
+       return err;
+}
+
+static
+int au_opts_parse_xino_itrunc_path(struct super_block *sb,
+                                  struct au_opt_xino_itrunc *xino_itrunc,
+                                  substring_t args[])
+{
+       int err;
+       aufs_bindex_t bend, bindex;
+       struct path path;
+       struct dentry *root;
+
+       err = vfsub_kern_path(args[0].from, lkup_dirflags, &path);
+       if (unlikely(err)) {
+               AuErr("lookup failed %s (%d)\n", args[0].from, err);
+               goto out;
+       }
+
+       xino_itrunc->bindex = -1;
+       root = sb->s_root;
+       aufs_read_lock(root, AuLock_FLUSH);
+       bend = au_sbend(sb);
+       for (bindex = 0; bindex <= bend; bindex++) {
+               if (au_h_dptr(root, bindex) == path.dentry) {
+                       xino_itrunc->bindex = bindex;
+                       break;
+               }
+       }
+       aufs_read_unlock(root, !AuLock_IR);
+       path_put(&path);
+
+       if (unlikely(xino_itrunc->bindex < 0)) {
+               AuErr("no such branch %s\n", args[0].from);
+               err = -EINVAL;
+       }
+
+ out:
+       return err;
+}
+
+/* called without aufs lock */
+int au_opts_parse(struct super_block *sb, char *str, struct au_opts *opts)
+{
+       int err, n, token;
+       aufs_bindex_t bindex;
+       unsigned char skipped;
+       struct dentry *root;
+       struct au_opt *opt, *opt_tail;
+       char *opt_str;
+       /* reduce the stack space */
+       union {
+               struct au_opt_xino_itrunc *xino_itrunc;
+               struct au_opt_wbr_create *create;
+       } u;
+       struct {
+               substring_t args[MAX_OPT_ARGS];
+       } *a;
+
+       err = -ENOMEM;
+       a = kmalloc(sizeof(*a), GFP_NOFS);
+       if (unlikely(!a))
+               goto out;
+
+       root = sb->s_root;
+       err = 0;
+       bindex = 0;
+       opt = opts->opt;
+       opt_tail = opt + opts->max_opt - 1;
+       opt->type = Opt_tail;
+       while (!err && (opt_str = strsep(&str, ",")) && *opt_str) {
+               err = -EINVAL;
+               skipped = 0;
+               token = match_token(opt_str, options, a->args);
+               switch (token) {
+               case Opt_br:
+                       err = 0;
+                       while (!err && (opt_str = strsep(&a->args[0].from, ":"))
+                              && *opt_str) {
+                               err = opt_add(opt, opt_str, opts->sb_flags,
+                                             bindex++);
+                               if (unlikely(!err && ++opt > opt_tail)) {
+                                       err = -E2BIG;
+                                       break;
+                               }
+                               opt->type = Opt_tail;
+                               skipped = 1;
+                       }
+                       break;
+               case Opt_add:
+                       if (unlikely(match_int(&a->args[0], &n))) {
+                               AuErr("bad integer in %s\n", opt_str);
+                               break;
+                       }
+                       bindex = n;
+                       err = opt_add(opt, a->args[1].from, opts->sb_flags,
+                                     bindex);
+                       if (!err)
+                               opt->type = token;
+                       break;
+               case Opt_append:
+                       err = opt_add(opt, a->args[0].from, opts->sb_flags,
+                                     /*dummy bindex*/1);
+                       if (!err)
+                               opt->type = token;
+                       break;
+               case Opt_prepend:
+                       err = opt_add(opt, a->args[0].from, opts->sb_flags,
+                                     /*bindex*/0);
+                       if (!err)
+                               opt->type = token;
+                       break;
+               case Opt_del:
+                       err = au_opts_parse_del(&opt->del, a->args);
+                       if (!err)
+                               opt->type = token;
+                       break;
+#if 0 /* reserved for future use */
+               case Opt_idel:
+                       del->pathname = "(indexed)";
+                       if (unlikely(match_int(&args[0], &n))) {
+                               AuErr("bad integer in %s\n", opt_str);
+                               break;
+                       }
+                       err = au_opts_parse_idel(sb, n, &opt->del, a->args);
+                       if (!err)
+                               opt->type = token;
+                       break;
+#endif
+               case Opt_mod:
+                       err = au_opts_parse_mod(&opt->mod, a->args);
+                       if (!err)
+                               opt->type = token;
+                       break;
+#ifdef IMOD /* reserved for future use */
+               case Opt_imod:
+                       u.mod->path = "(indexed)";
+                       if (unlikely(match_int(&a->args[0], &n))) {
+                               AuErr("bad integer in %s\n", opt_str);
+                               break;
+                       }
+                       err = au_opts_parse_imod(sb, n, &opt->mod, a->args);
+                       if (!err)
+                               opt->type = token;
+                       break;
+#endif
+               case Opt_xino:
+                       err = au_opts_parse_xino(sb, &opt->xino, a->args);
+                       if (!err)
+                               opt->type = token;
+                       break;
+
+               case Opt_trunc_xino_path:
+                       err = au_opts_parse_xino_itrunc_path
+                               (sb, &opt->xino_itrunc, a->args);
+                       if (!err)
+                               opt->type = token;
+                       break;
+
+               case Opt_itrunc_xino:
+                       u.xino_itrunc = &opt->xino_itrunc;
+                       if (unlikely(match_int(&a->args[0], &n))) {
+                               AuErr("bad integer in %s\n", opt_str);
+                               break;
+                       }
+                       u.xino_itrunc->bindex = n;
+                       aufs_read_lock(root, AuLock_FLUSH);
+                       if (n < 0 || au_sbend(sb) < n) {
+                               AuErr("out of bounds, %d\n", n);
+                               aufs_read_unlock(root, !AuLock_IR);
+                               break;
+                       }
+                       aufs_read_unlock(root, !AuLock_IR);
+                       err = 0;
+                       opt->type = token;
+                       break;
+
+               case Opt_dirwh:
+                       if (unlikely(match_int(&a->args[0], &opt->dirwh)))
+                               break;
+                       err = 0;
+                       opt->type = token;
+                       break;
+
+               case Opt_rdcache:
+                       if (unlikely(match_int(&a->args[0], &opt->rdcache)))
+                               break;
+                       err = 0;
+                       opt->type = token;
+                       break;
+               case Opt_rdblk:
+                       if (unlikely(match_int(&a->args[0], &n)
+                                    || n <= 0
+                                    || n > KMALLOC_MAX_SIZE)) {
+                               AuErr("bad integer in %s\n", opt_str);
+                               break;
+                       }
+                       if (unlikely(n < NAME_MAX)) {
+                               AuErr("rdblk must be larger than %d\n",
+                                     NAME_MAX);
+                               break;
+                       }
+                       opt->rdblk = n;
+                       err = 0;
+                       opt->type = token;
+                       break;
+               case Opt_rdhash:
+                       if (unlikely(match_int(&a->args[0], &n)
+                                    || n <= 0
+                                    || n * sizeof(struct hlist_head)
+                                    > KMALLOC_MAX_SIZE)) {
+                               AuErr("bad integer in %s\n", opt_str);
+                               break;
+                       }
+                       opt->rdhash = n;
+                       err = 0;
+                       opt->type = token;
+                       break;
+
+               case Opt_trunc_xino:
+               case Opt_notrunc_xino:
+               case Opt_noxino:
+               case Opt_trunc_xib:
+               case Opt_notrunc_xib:
+               case Opt_plink:
+               case Opt_noplink:
+               case Opt_list_plink:
+               case Opt_diropq_a:
+               case Opt_diropq_w:
+               case Opt_warn_perm:
+               case Opt_nowarn_perm:
+               case Opt_refrof:
+               case Opt_norefrof:
+               case Opt_verbose:
+               case Opt_noverbose:
+               case Opt_sum:
+               case Opt_nosum:
+               case Opt_wsum:
+                       err = 0;
+                       opt->type = token;
+                       break;
+
+               case Opt_udba:
+                       opt->udba = udba_val(a->args[0].from);
+                       if (opt->udba >= 0) {
+                               err = 0;
+                               opt->type = token;
+                       } else
+                               AuErr("wrong value, %s\n", opt_str);
+                       break;
+
+               case Opt_wbr_create:
+                       u.create = &opt->wbr_create;
+                       u.create->wbr_create
+                               = au_wbr_create_val(a->args[0].from, u.create);
+                       if (u.create->wbr_create >= 0) {
+                               err = 0;
+                               opt->type = token;
+                       } else
+                               AuErr("wrong value, %s\n", opt_str);
+                       break;
+               case Opt_wbr_copyup:
+                       opt->wbr_copyup = au_wbr_copyup_val(a->args[0].from);
+                       if (opt->wbr_copyup >= 0) {
+                               err = 0;
+                               opt->type = token;
+                       } else
+                               AuErr("wrong value, %s\n", opt_str);
+                       break;
+
+               case Opt_ignore:
+                       AuWarn("ignored %s\n", opt_str);
+                       /*FALLTHROUGH*/
+               case Opt_ignore_silent:
+                       skipped = 1;
+                       err = 0;
+                       break;
+               case Opt_err:
+                       AuErr("unknown option %s\n", opt_str);
+                       break;
+               }
+
+               if (!err && !skipped) {
+                       if (unlikely(++opt > opt_tail)) {
+                               err = -E2BIG;
+                               opt--;
+                               opt->type = Opt_tail;
+                               break;
+                       }
+                       opt->type = Opt_tail;
+               }
+       }
+
+       kfree(a);
+       dump_opts(opts);
+       if (unlikely(err))
+               au_opts_free(opts);
+
+ out:
+       return err;
+}
+
+static int au_opt_wbr_create(struct super_block *sb,
+                            struct au_opt_wbr_create *create)
+{
+       int err;
+       struct au_sbinfo *sbinfo;
+
+       err = 1; /* handled */
+       sbinfo = au_sbi(sb);
+       if (sbinfo->si_wbr_create_ops->fin) {
+               err = sbinfo->si_wbr_create_ops->fin(sb);
+               if (!err)
+                       err = 1;
+       }
+
+       sbinfo->si_wbr_create = create->wbr_create;
+       sbinfo->si_wbr_create_ops = au_wbr_create_ops + create->wbr_create;
+       switch (create->wbr_create) {
+       case AuWbrCreate_MFSRRV:
+       case AuWbrCreate_MFSRR:
+               sbinfo->si_wbr_mfs.mfsrr_watermark = create->mfsrr_watermark;
+               /*FALLTHROUGH*/
+       case AuWbrCreate_MFS:
+       case AuWbrCreate_MFSV:
+       case AuWbrCreate_PMFS:
+       case AuWbrCreate_PMFSV:
+               sbinfo->si_wbr_mfs.mfs_expire = create->mfs_second * HZ;
+               break;
+       }
+
+       if (sbinfo->si_wbr_create_ops->init)
+               sbinfo->si_wbr_create_ops->init(sb); /* ignore */
+
+       return err;
+}
+
+/*
+ * returns,
+ * plus: processed without an error
+ * zero: unprocessed
+ */
+static int au_opt_simple(struct super_block *sb, struct au_opt *opt,
+                        struct au_opts *opts)
+{
+       int err;
+       struct au_sbinfo *sbinfo;
+
+       err = 1; /* handled */
+       sbinfo = au_sbi(sb);
+       switch (opt->type) {
+       case Opt_udba:
+               sbinfo->si_mntflags &= ~AuOptMask_UDBA;
+               sbinfo->si_mntflags |= opt->udba;
+               opts->given_udba |= opt->udba;
+               break;
+
+       case Opt_plink:
+               au_opt_set(sbinfo->si_mntflags, PLINK);
+               break;
+       case Opt_noplink:
+               if (au_opt_test(sbinfo->si_mntflags, PLINK))
+                       au_plink_put(sb);
+               au_opt_clr(sbinfo->si_mntflags, PLINK);
+               break;
+       case Opt_list_plink:
+               if (au_opt_test(sbinfo->si_mntflags, PLINK))
+                       au_plink_list(sb);
+               break;
+
+       case Opt_diropq_a:
+               au_opt_set(sbinfo->si_mntflags, ALWAYS_DIROPQ);
+               break;
+       case Opt_diropq_w:
+               au_opt_clr(sbinfo->si_mntflags, ALWAYS_DIROPQ);
+               break;
+
+       case Opt_warn_perm:
+               au_opt_set(sbinfo->si_mntflags, WARN_PERM);
+               break;
+       case Opt_nowarn_perm:
+               au_opt_clr(sbinfo->si_mntflags, WARN_PERM);
+               break;
+
+       case Opt_refrof:
+               au_opt_set(sbinfo->si_mntflags, REFROF);
+               break;
+       case Opt_norefrof:
+               au_opt_clr(sbinfo->si_mntflags, REFROF);
+               break;
+
+       case Opt_verbose:
+               au_opt_set(sbinfo->si_mntflags, VERBOSE);
+               break;
+       case Opt_noverbose:
+               au_opt_clr(sbinfo->si_mntflags, VERBOSE);
+               break;
+
+       case Opt_sum:
+               au_opt_set(sbinfo->si_mntflags, SUM);
+               break;
+       case Opt_wsum:
+               au_opt_clr(sbinfo->si_mntflags, SUM);
+               au_opt_set(sbinfo->si_mntflags, SUM_W);
+       case Opt_nosum:
+               au_opt_clr(sbinfo->si_mntflags, SUM);
+               au_opt_clr(sbinfo->si_mntflags, SUM_W);
+               break;
+
+       case Opt_wbr_create:
+               err = au_opt_wbr_create(sb, &opt->wbr_create);
+               break;
+       case Opt_wbr_copyup:
+               sbinfo->si_wbr_copyup = opt->wbr_copyup;
+               sbinfo->si_wbr_copyup_ops = au_wbr_copyup_ops + opt->wbr_copyup;
+               break;
+
+       case Opt_dirwh:
+               sbinfo->si_dirwh = opt->dirwh;
+               break;
+
+       case Opt_rdcache:
+               sbinfo->si_rdcache = opt->rdcache * HZ;
+               break;
+       case Opt_rdblk:
+               sbinfo->si_rdblk = opt->rdblk;
+               break;
+       case Opt_rdhash:
+               sbinfo->si_rdhash = opt->rdhash;
+               break;
+
+       case Opt_trunc_xino:
+               au_opt_set(sbinfo->si_mntflags, TRUNC_XINO);
+               break;
+       case Opt_notrunc_xino:
+               au_opt_clr(sbinfo->si_mntflags, TRUNC_XINO);
+               break;
+
+       case Opt_trunc_xino_path:
+       case Opt_itrunc_xino:
+               err = au_xino_trunc(sb, opt->xino_itrunc.bindex);
+               if (!err)
+                       err = 1;
+               break;
+
+       case Opt_trunc_xib:
+               au_fset_opts(opts->flags, TRUNC_XIB);
+               break;
+       case Opt_notrunc_xib:
+               au_fclr_opts(opts->flags, TRUNC_XIB);
+               break;
+
+       default:
+               err = 0;
+               break;
+       }
+
+       return err;
+}
+
+/*
+ * returns tri-state.
+ * plus: processed without an error
+ * zero: unprocessed
+ * minus: error
+ */
+static int au_opt_br(struct super_block *sb, struct au_opt *opt,
+                    struct au_opts *opts)
+{
+       int err, do_refresh;
+
+       err = 0;
+       switch (opt->type) {
+       case Opt_append:
+               opt->add.bindex = au_sbend(sb) + 1;
+               if (opt->add.bindex < 0)
+                       opt->add.bindex = 0;
+               goto add;
+       case Opt_prepend:
+               opt->add.bindex = 0;
+       add:
+       case Opt_add:
+               err = au_br_add(sb, &opt->add,
+                               au_ftest_opts(opts->flags, REMOUNT));
+               if (!err) {
+                       err = 1;
+                       au_fset_opts(opts->flags, REFRESH_DIR);
+                       if (au_br_whable(opt->add.perm))
+                               au_fset_opts(opts->flags, REFRESH_NONDIR);
+               }
+               break;
+
+       case Opt_del:
+       case Opt_idel:
+               err = au_br_del(sb, &opt->del,
+                               au_ftest_opts(opts->flags, REMOUNT));
+               if (!err) {
+                       err = 1;
+                       au_fset_opts(opts->flags, TRUNC_XIB);
+                       au_fset_opts(opts->flags, REFRESH_DIR);
+                       au_fset_opts(opts->flags, REFRESH_NONDIR);
+               }
+               break;
+
+       case Opt_mod:
+       case Opt_imod:
+               err = au_br_mod(sb, &opt->mod,
+                               au_ftest_opts(opts->flags, REMOUNT),
+                               &do_refresh);
+               if (!err) {
+                       err = 1;
+                       if (do_refresh) {
+                               au_fset_opts(opts->flags, REFRESH_DIR);
+                               au_fset_opts(opts->flags, REFRESH_NONDIR);
+                       }
+               }
+               break;
+       }
+
+       return err;
+}
+
+static int au_opt_xino(struct super_block *sb, struct au_opt *opt,
+                      struct au_opt_xino **opt_xino,
+                      struct au_opts *opts)
+{
+       int err;
+       aufs_bindex_t bend, bindex;
+       struct dentry *root, *parent, *h_root;
+
+       err = 0;
+       switch (opt->type) {
+       case Opt_xino:
+               err = au_xino_set(sb, &opt->xino,
+                                 !!au_ftest_opts(opts->flags, REMOUNT));
+               if (unlikely(err))
+                       break;
+
+               *opt_xino = &opt->xino;
+               au_xino_brid_set(sb, -1);
+
+               /* safe d_parent access */
+               parent = opt->xino.file->f_dentry->d_parent;
+               root = sb->s_root;
+               bend = au_sbend(sb);
+               for (bindex = 0; bindex <= bend; bindex++) {
+                       h_root = au_h_dptr(root, bindex);
+                       if (h_root == parent) {
+                               au_xino_brid_set(sb, au_sbr_id(sb, bindex));
+                               break;
+                       }
+               }
+               break;
+
+       case Opt_noxino:
+               au_xino_clr(sb);
+               au_xino_brid_set(sb, -1);
+               *opt_xino = (void *)-1;
+               break;
+       }
+
+       return err;
+}
+
+int au_opts_verify(struct super_block *sb, unsigned long sb_flags,
+                  unsigned int pending)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       unsigned char do_plink, skip, do_free;
+       struct au_branch *br;
+       struct au_wbr *wbr;
+       struct dentry *root;
+       struct inode *dir, *h_dir;
+       struct au_sbinfo *sbinfo;
+       struct au_hinode *hdir;
+
+       sbinfo = au_sbi(sb);
+       AuDebugOn(!(sbinfo->si_mntflags & AuOptMask_UDBA));
+
+       if (unlikely(!(sb_flags & MS_RDONLY)
+                    && !au_br_writable(au_sbr_perm(sb, 0))))
+               AuWarn("first branch should be rw\n");
+
+       if (au_opt_test((sbinfo->si_mntflags | pending), UDBA_HINOTIFY)
+           && !au_opt_test(sbinfo->si_mntflags, XINO))
+               AuWarn("udba=inotify requires xino\n");
+
+       err = 0;
+       root = sb->s_root;
+       dir = sb->s_root->d_inode;
+       do_plink = !!au_opt_test(sbinfo->si_mntflags, PLINK);
+       bend = au_sbend(sb);
+       for (bindex = 0; !err && bindex <= bend; bindex++) {
+               skip = 0;
+               h_dir = au_h_iptr(dir, bindex);
+               br = au_sbr(sb, bindex);
+               do_free = 0;
+
+               wbr = br->br_wbr;
+               if (wbr)
+                       wbr_wh_read_lock(wbr);
+
+               switch (br->br_perm) {
+               case AuBrPerm_RO:
+               case AuBrPerm_ROWH:
+               case AuBrPerm_RR:
+               case AuBrPerm_RRWH:
+                       do_free = !!wbr;
+                       skip = (!wbr
+                               || (!wbr->wbr_whbase
+                                   && !wbr->wbr_plink
+                                   && !wbr->wbr_orph));
+                       break;
+
+               case AuBrPerm_RWNoLinkWH:
+                       /* skip = (!br->br_whbase && !br->br_orph); */
+                       skip = (!wbr || !wbr->wbr_whbase);
+                       if (skip && wbr) {
+                               if (do_plink)
+                                       skip = !!wbr->wbr_plink;
+                               else
+                                       skip = !wbr->wbr_plink;
+                       }
+                       break;
+
+               case AuBrPerm_RW:
+                       /* skip = (br->br_whbase && br->br_ohph); */
+                       skip = (wbr && wbr->wbr_whbase);
+                       if (skip) {
+                               if (do_plink)
+                                       skip = !!wbr->wbr_plink;
+                               else
+                                       skip = !wbr->wbr_plink;
+                       }
+                       break;
+
+               default:
+                       BUG();
+               }
+               if (wbr)
+                       wbr_wh_read_unlock(wbr);
+
+               if (skip)
+                       continue;
+
+               hdir = au_hi(dir, bindex);
+               au_hin_imtx_lock_nested(hdir, AuLsc_I_PARENT);
+               if (wbr)
+                       wbr_wh_write_lock(wbr);
+               err = au_wh_init(au_h_dptr(root, bindex), br, sb);
+               if (wbr)
+                       wbr_wh_write_unlock(wbr);
+               au_hin_imtx_unlock(hdir);
+
+               if (!err && do_free) {
+                       kfree(wbr);
+                       br->br_wbr = NULL;
+               }
+       }
+
+       return err;
+}
+
+int au_opts_mount(struct super_block *sb, struct au_opts *opts)
+{
+       int err;
+       unsigned int tmp;
+       aufs_bindex_t bend;
+       struct au_opt *opt;
+       struct au_opt_xino *opt_xino, xino;
+       struct au_sbinfo *sbinfo;
+
+       err = 0;
+       opt_xino = NULL;
+       opt = opts->opt;
+       while (err >= 0 && opt->type != Opt_tail)
+               err = au_opt_simple(sb, opt++, opts);
+       if (err > 0)
+               err = 0;
+       else if (unlikely(err < 0))
+               goto out;
+
+       /* disable xino and udba temporary */
+       sbinfo = au_sbi(sb);
+       tmp = sbinfo->si_mntflags;
+       au_opt_clr(sbinfo->si_mntflags, XINO);
+       au_opt_set_udba(sbinfo->si_mntflags, UDBA_REVAL);
+
+       opt = opts->opt;
+       while (err >= 0 && opt->type != Opt_tail)
+               err = au_opt_br(sb, opt++, opts);
+       if (err > 0)
+               err = 0;
+       else if (unlikely(err < 0))
+               goto out;
+
+       bend = au_sbend(sb);
+       if (unlikely(bend < 0)) {
+               err = -EINVAL;
+               AuErr("no branches\n");
+               goto out;
+       }
+
+       if (au_opt_test(tmp, XINO))
+               au_opt_set(sbinfo->si_mntflags, XINO);
+       opt = opts->opt;
+       while (!err && opt->type != Opt_tail)
+               err = au_opt_xino(sb, opt++, &opt_xino, opts);
+       if (unlikely(err))
+               goto out;
+
+       err = au_opts_verify(sb, sb->s_flags, tmp);
+       if (unlikely(err))
+               goto out;
+
+       /* restore xino */
+       if (au_opt_test(tmp, XINO) && !opt_xino) {
+               xino.file = au_xino_def(sb);
+               err = PTR_ERR(xino.file);
+               if (IS_ERR(xino.file))
+                       goto out;
+
+               err = au_xino_set(sb, &xino, /*remount*/0);
+               fput(xino.file);
+               if (unlikely(err))
+                       goto out;
+       }
+
+       /* restore udba */
+       sbinfo->si_mntflags &= ~AuOptMask_UDBA;
+       sbinfo->si_mntflags |= (tmp & AuOptMask_UDBA);
+       if (au_opt_test(tmp, UDBA_HINOTIFY)) {
+               struct inode *dir = sb->s_root->d_inode;
+               au_reset_hinotify(dir,
+                                 au_hi_flags(dir, /*isdir*/1) & ~AuHi_XINO);
+       }
+
+ out:
+       return err;
+}
+
+int au_opts_remount(struct super_block *sb, struct au_opts *opts)
+{
+       int err, rerr;
+       struct inode *dir;
+       struct au_opt_xino *opt_xino;
+       struct au_opt *opt;
+       struct au_sbinfo *sbinfo;
+
+       dir = sb->s_root->d_inode;
+       sbinfo = au_sbi(sb);
+       err = 0;
+       opt_xino = NULL;
+       opt = opts->opt;
+       while (err >= 0 && opt->type != Opt_tail) {
+               err = au_opt_simple(sb, opt, opts);
+               if (!err)
+                       err = au_opt_br(sb, opt, opts);
+               if (!err)
+                       err = au_opt_xino(sb, opt, &opt_xino, opts);
+               opt++;
+       }
+       if (err > 0)
+               err = 0;
+       AuTraceErr(err);
+       /* go on even err */
+
+       rerr = au_opts_verify(sb, opts->sb_flags, /*pending*/0);
+       if (unlikely(rerr && !err))
+               err = rerr;
+
+       if (au_ftest_opts(opts->flags, TRUNC_XIB)) {
+               rerr = au_xib_trunc(sb);
+               if (unlikely(rerr && !err))
+                       err = rerr;
+       }
+
+       /* will be handled by the caller */
+       if (!au_ftest_opts(opts->flags, REFRESH_DIR)
+           && (opts->given_udba || au_opt_test(sbinfo->si_mntflags, XINO)))
+               au_fset_opts(opts->flags, REFRESH_DIR);
+
+       AuDbg("status 0x%x\n", opts->flags);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+unsigned int au_opt_udba(struct super_block *sb)
+{
+       return au_mntflags(sb) & AuOptMask_UDBA;
+}
diff --git a/fs/aufs/opts.h b/fs/aufs/opts.h
new file mode 100644
index 0000000..275702c
--- /dev/null
+++ b/fs/aufs/opts.h
@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * mount options/flags
+ */
+
+#ifndef __AUFS_OPTS_H__
+#define __AUFS_OPTS_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/aufs_type.h>
+
+/* ---------------------------------------------------------------------- */
+
+/* mount flags */
+#define AuOpt_XINO             1               /* external inode number bitmap
+                                                  and translation table */
+#define AuOpt_TRUNC_XINO       (1 << 1)        /* truncate xino files */
+#define AuOpt_UDBA_NONE                (1 << 2)        /* users direct branch access */
+#define AuOpt_UDBA_REVAL       (1 << 3)
+#define AuOpt_UDBA_HINOTIFY    (1 << 4)
+#define AuOpt_PLINK            (1 << 5)        /* pseudo-link */
+#define AuOpt_DIRPERM1         (1 << 6)        /* unimplemented */
+#define AuOpt_REFROF           (1 << 7)        /* unimplemented */
+#define AuOpt_ALWAYS_DIROPQ    (1 << 8)        /* policy to creating diropq */
+#define AuOpt_SUM              (1 << 9)        /* summation for statfs(2) */
+#define AuOpt_SUM_W            (1 << 10)       /* unimplemented */
+#define AuOpt_WARN_PERM                (1 << 11)       /* warn when add-branch */
+#define AuOpt_VERBOSE          (1 << 12)       /* busy inode when del-branch */
+
+#ifndef CONFIG_AUFS_HINOTIFY
+#undef AuOpt_UDBA_HINOTIFY
+#define AuOpt_UDBA_HINOTIFY    0
+#endif
+
+#define AuOpt_Def      (AuOpt_XINO \
+                        | AuOpt_UDBA_REVAL \
+                        | AuOpt_PLINK \
+                        /* | AuOpt_DIRPERM1 */ \
+                        | AuOpt_WARN_PERM)
+#define AuOptMask_UDBA (AuOpt_UDBA_NONE \
+                        | AuOpt_UDBA_REVAL \
+                        | AuOpt_UDBA_HINOTIFY)
+
+#define au_opt_test(flags, name)       (flags & AuOpt_##name)
+#define au_opt_set(flags, name) do { \
+       BUILD_BUG_ON(AuOpt_##name & AuOptMask_UDBA); \
+       ((flags) |= AuOpt_##name); \
+} while (0)
+#define au_opt_set_udba(flags, name) do { \
+       (flags) &= ~AuOptMask_UDBA; \
+       ((flags) |= AuOpt_##name); \
+} while (0)
+#define au_opt_clr(flags, name)                { ((flags) &= ~AuOpt_##name); }
+
+/* ---------------------------------------------------------------------- */
+
+/* policies to select one among multiple writable branches */
+enum {
+       AuWbrCreate_TDP,        /* top down parent */
+       AuWbrCreate_RR,         /* round robin */
+       AuWbrCreate_MFS,        /* most free space */
+       AuWbrCreate_MFSV,       /* mfs with seconds */
+       AuWbrCreate_MFSRR,      /* mfs then rr */
+       AuWbrCreate_MFSRRV,     /* mfs then rr with seconds */
+       AuWbrCreate_PMFS,       /* parent and mfs */
+       AuWbrCreate_PMFSV,      /* parent and mfs with seconds */
+
+       AuWbrCreate_Def = AuWbrCreate_TDP
+};
+
+enum {
+       AuWbrCopyup_TDP,        /* top down parent */
+       AuWbrCopyup_BUP,        /* bottom up parent */
+       AuWbrCopyup_BU,         /* bottom up */
+
+       AuWbrCopyup_Def = AuWbrCopyup_TDP
+};
+
+/* ---------------------------------------------------------------------- */
+
+struct au_opt_add {
+       aufs_bindex_t   bindex;
+       char            *pathname;
+       int             perm;
+       struct path     path;
+};
+
+struct au_opt_del {
+       char            *pathname;
+       struct path     h_path;
+};
+
+struct au_opt_mod {
+       char            *path;
+       int             perm;
+       struct dentry   *h_root;
+};
+
+struct au_opt_xino {
+       char            *path;
+       struct file     *file;
+};
+
+struct au_opt_xino_itrunc {
+       aufs_bindex_t   bindex;
+};
+
+struct au_opt_wbr_create {
+       int                     wbr_create;
+       int                     mfs_second;
+       unsigned long long      mfsrr_watermark;
+};
+
+struct au_opt {
+       int type;
+       union {
+               struct au_opt_xino      xino;
+               struct au_opt_xino_itrunc xino_itrunc;
+               struct au_opt_add       add;
+               struct au_opt_del       del;
+               struct au_opt_mod       mod;
+               int                     dirwh;
+               int                     rdcache;
+               unsigned int            rdblk;
+               unsigned int            rdhash;
+               int                     udba;
+               struct au_opt_wbr_create wbr_create;
+               int                     wbr_copyup;
+       };
+};
+
+/* opts flags */
+#define AuOpts_REMOUNT         1
+#define AuOpts_REFRESH_DIR     (1 << 1)
+#define AuOpts_REFRESH_NONDIR  (1 << 2)
+#define AuOpts_TRUNC_XIB       (1 << 3)
+#define au_ftest_opts(flags, name)     ((flags) & AuOpts_##name)
+#define au_fset_opts(flags, name)      { (flags) |= AuOpts_##name; }
+#define au_fclr_opts(flags, name)      { (flags) &= ~AuOpts_##name; }
+
+struct au_opts {
+       struct au_opt   *opt;
+       int             max_opt;
+
+       unsigned int    given_udba;
+       unsigned int    flags;
+       unsigned long   sb_flags;
+};
+
+/* ---------------------------------------------------------------------- */
+
+const char *au_optstr_br_perm(int brperm);
+const char *au_optstr_udba(int udba);
+const char *au_optstr_wbr_copyup(int wbr_copyup);
+const char *au_optstr_wbr_create(int wbr_create);
+
+void au_opts_free(struct au_opts *opts);
+int au_opts_parse(struct super_block *sb, char *str, struct au_opts *opts);
+int au_opts_verify(struct super_block *sb, unsigned long sb_flags,
+                  unsigned int pending);
+int au_opts_mount(struct super_block *sb, struct au_opts *opts);
+int au_opts_remount(struct super_block *sb, struct au_opts *opts);
+
+unsigned int au_opt_udba(struct super_block *sb);
+
+/* ---------------------------------------------------------------------- */
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_OPTS_H__ */
diff --git a/fs/aufs/plink.c b/fs/aufs/plink.c
new file mode 100644
index 0000000..62d258f
--- /dev/null
+++ b/fs/aufs/plink.c
@@ -0,0 +1,335 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * pseudo-link
+ */
+
+#include "aufs.h"
+
+/*
+ * during a user process maintains the pseudo-links,
+ * prohibit adding a new plink and branch manipulation.
+ */
+void au_plink_block_maintain(struct super_block *sb)
+{
+       struct au_sbinfo *sbi = au_sbi(sb);
+       /* gave up wake_up_bit() */
+       wait_event(sbi->si_plink_wq, !au_ftest_si(sbi, MAINTAIN_PLINK));
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct pseudo_link {
+       struct list_head list;
+       struct inode *inode;
+};
+
+#ifdef CONFIG_AUFS_DEBUG
+void au_plink_list(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+       struct list_head *plink_list;
+       struct pseudo_link *plink;
+
+       sbinfo = au_sbi(sb);
+       AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+       plink_list = &sbinfo->si_plink.head;
+       spin_lock(&sbinfo->si_plink.spin);
+       list_for_each_entry(plink, plink_list, list)
+               AuDbg("%lu\n", plink->inode->i_ino);
+       spin_unlock(&sbinfo->si_plink.spin);
+}
+#endif
+
+/* is the inode pseudo-linked? */
+int au_plink_test(struct inode *inode)
+{
+       int found;
+       struct au_sbinfo *sbinfo;
+       struct list_head *plink_list;
+       struct pseudo_link *plink;
+
+       sbinfo = au_sbi(inode->i_sb);
+       AuDebugOn(!au_opt_test(au_mntflags(inode->i_sb), PLINK));
+
+       found = 0;
+       plink_list = &sbinfo->si_plink.head;
+       spin_lock(&sbinfo->si_plink.spin);
+       list_for_each_entry(plink, plink_list, list)
+               if (plink->inode == inode) {
+                       found = 1;
+                       break;
+               }
+       spin_unlock(&sbinfo->si_plink.spin);
+       return found;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * generate a name for plink.
+ * the file will be stored under AUFS_WH_PLINKDIR.
+ */
+/* 20 is max digits length of ulong 64 */
+#define PLINK_NAME_LEN ((20 + 1) * 2)
+
+static int plink_name(char *name, int len, struct inode *inode,
+                     aufs_bindex_t bindex)
+{
+       int rlen;
+       struct inode *h_inode;
+
+       h_inode = au_h_iptr(inode, bindex);
+       rlen = snprintf(name, len, "%lu.%lu", inode->i_ino, h_inode->i_ino);
+       return rlen;
+}
+
+/* lookup the plink-ed @inode under the branch at @bindex */
+struct dentry *au_plink_lkup(struct inode *inode, aufs_bindex_t bindex)
+{
+       struct dentry *h_dentry, *h_parent;
+       struct au_branch *br;
+       struct inode *h_dir;
+       char a[PLINK_NAME_LEN];
+       struct qstr tgtname = {
+               .name   = a
+       };
+
+       br = au_sbr(inode->i_sb, bindex);
+       h_parent = br->br_wbr->wbr_plink;
+       h_dir = h_parent->d_inode;
+       tgtname.len = plink_name(a, sizeof(a), inode, bindex);
+
+       /* always superio. */
+       mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_CHILD2);
+       h_dentry = au_sio_lkup_one(&tgtname, h_parent, br);
+       mutex_unlock(&h_dir->i_mutex);
+       return h_dentry;
+}
+
+/* create a pseudo-link */
+static int do_whplink(struct qstr *tgt, struct dentry *h_parent,
+                     struct dentry *h_dentry, struct au_branch *br)
+{
+       int err;
+       struct path h_path = {
+               .mnt = br->br_mnt
+       };
+       struct inode *h_dir;
+
+       h_dir = h_parent->d_inode;
+ again:
+       h_path.dentry = au_lkup_one(tgt, h_parent, br, /*nd*/NULL);
+       err = PTR_ERR(h_path.dentry);
+       if (IS_ERR(h_path.dentry))
+               goto out;
+
+       err = 0;
+       /* wh.plink dir is not monitored */
+       if (h_path.dentry->d_inode
+           && h_path.dentry->d_inode != h_dentry->d_inode) {
+               err = vfsub_unlink(h_dir, &h_path, /*force*/0);
+               dput(h_path.dentry);
+               h_path.dentry = NULL;
+               if (!err)
+                       goto again;
+       }
+       if (!err && !h_path.dentry->d_inode)
+               err = vfsub_link(h_dentry, h_dir, &h_path);
+       dput(h_path.dentry);
+
+ out:
+       return err;
+}
+
+struct do_whplink_args {
+       int *errp;
+       struct qstr *tgt;
+       struct dentry *h_parent;
+       struct dentry *h_dentry;
+       struct au_branch *br;
+};
+
+static void call_do_whplink(void *args)
+{
+       struct do_whplink_args *a = args;
+       *a->errp = do_whplink(a->tgt, a->h_parent, a->h_dentry, a->br);
+}
+
+static int whplink(struct dentry *h_dentry, struct inode *inode,
+                  aufs_bindex_t bindex, struct au_branch *br)
+{
+       int err, wkq_err;
+       struct au_wbr *wbr;
+       struct dentry *h_parent;
+       struct inode *h_dir;
+       char a[PLINK_NAME_LEN];
+       struct qstr tgtname = {
+               .name = a
+       };
+
+       wbr = au_sbr(inode->i_sb, bindex)->br_wbr;
+       h_parent = wbr->wbr_plink;
+       h_dir = h_parent->d_inode;
+       tgtname.len = plink_name(a, sizeof(a), inode, bindex);
+
+       /* always superio. */
+       mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_CHILD2);
+       if (!au_test_wkq(current)) {
+               struct do_whplink_args args = {
+                       .errp           = &err,
+                       .tgt            = &tgtname,
+                       .h_parent       = h_parent,
+                       .h_dentry       = h_dentry,
+                       .br             = br
+               };
+               wkq_err = au_wkq_wait(call_do_whplink, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       } else
+               err = do_whplink(&tgtname, h_parent, h_dentry, br);
+       mutex_unlock(&h_dir->i_mutex);
+
+       return err;
+}
+
+/* free a single plink */
+static void do_put_plink(struct pseudo_link *plink, int do_del)
+{
+       iput(plink->inode);
+       if (do_del)
+               list_del(&plink->list);
+       kfree(plink);
+}
+
+/*
+ * create a new pseudo-link for @h_dentry on @bindex.
+ * the linked inode is held in aufs @inode.
+ */
+void au_plink_append(struct inode *inode, aufs_bindex_t bindex,
+                    struct dentry *h_dentry)
+{
+       struct super_block *sb;
+       struct au_sbinfo *sbinfo;
+       struct list_head *plink_list;
+       struct pseudo_link *plink;
+       int found, err, cnt;
+
+       sb = inode->i_sb;
+       sbinfo = au_sbi(sb);
+       AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+       err = 0;
+       cnt = 0;
+       found = 0;
+       plink_list = &sbinfo->si_plink.head;
+       spin_lock(&sbinfo->si_plink.spin);
+       list_for_each_entry(plink, plink_list, list) {
+               cnt++;
+               if (plink->inode == inode) {
+                       found = 1;
+                       break;
+               }
+       }
+       if (found) {
+               spin_unlock(&sbinfo->si_plink.spin);
+               return;
+       }
+
+       plink = NULL;
+       if (!found) {
+               plink = kmalloc(sizeof(*plink), GFP_ATOMIC);
+               if (plink) {
+                       plink->inode = au_igrab(inode);
+                       list_add(&plink->list, plink_list);
+                       cnt++;
+               } else
+                       err = -ENOMEM;
+       }
+       spin_unlock(&sbinfo->si_plink.spin);
+
+       if (!err) {
+               au_plink_block_maintain(sb);
+               err = whplink(h_dentry, inode, bindex, au_sbr(sb, bindex));
+       }
+
+       if (unlikely(cnt > AUFS_PLINK_WARN))
+               AuWarn1("unexpectedly many pseudo links, %d\n", cnt);
+       if (unlikely(err)) {
+               AuWarn("err %d, damaged pseudo link.\n", err);
+               if (!found && plink)
+                       do_put_plink(plink, /*do_del*/1);
+       }
+}
+
+/* free all plinks */
+void au_plink_put(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+       struct list_head *plink_list;
+       struct pseudo_link *plink, *tmp;
+
+       sbinfo = au_sbi(sb);
+       AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+       plink_list = &sbinfo->si_plink.head;
+       /* no spin_lock since sbinfo is write-locked */
+       list_for_each_entry_safe(plink, tmp, plink_list, list)
+               do_put_plink(plink, 0);
+       INIT_LIST_HEAD(plink_list);
+}
+
+/* free the plinks on a branch specified by @br_id */
+void au_plink_half_refresh(struct super_block *sb, aufs_bindex_t br_id)
+{
+       struct au_sbinfo *sbinfo;
+       struct list_head *plink_list;
+       struct pseudo_link *plink, *tmp;
+       struct inode *inode;
+       aufs_bindex_t bstart, bend, bindex;
+       unsigned char do_put;
+
+       sbinfo = au_sbi(sb);
+       AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+       plink_list = &sbinfo->si_plink.head;
+       /* no spin_lock since sbinfo is write-locked */
+       list_for_each_entry_safe(plink, tmp, plink_list, list) {
+               do_put = 0;
+               inode = au_igrab(plink->inode);
+               ii_write_lock_child(inode);
+               bstart = au_ibstart(inode);
+               bend = au_ibend(inode);
+               if (bstart >= 0) {
+                       for (bindex = bstart; bindex <= bend; bindex++) {
+                               if (!au_h_iptr(inode, bindex)
+                                   || au_ii_br_id(inode, bindex) != br_id)
+                                       continue;
+                               au_set_h_iptr(inode, bindex, NULL, 0);
+                               do_put = 1;
+                               break;
+                       }
+               } else
+                       do_put_plink(plink, 1);
+
+               if (do_put) {
+                       for (bindex = bstart; bindex <= bend; bindex++)
+                               if (au_h_iptr(inode, bindex)) {
+                                       do_put = 0;
+                                       break;
+                               }
+                       if (do_put)
+                               do_put_plink(plink, 1);
+               }
+               ii_write_unlock(inode);
+               iput(inode);
+       }
+}
diff --git a/fs/aufs/rwsem.h b/fs/aufs/rwsem.h
new file mode 100644
index 0000000..d569243
--- /dev/null
+++ b/fs/aufs/rwsem.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * simple read-write semaphore wrappers
+ */
+
+#ifndef __AUFS_RWSEM_H__
+#define __AUFS_RWSEM_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+
+#define au_rwsem_destroy(rw)   AuDebugOn(rwsem_is_locked(rw))
+#define AuRwMustNoWaiters(rw)  AuDebugOn(!list_empty(&(rw)->wait_list))
+
+#define AuSimpleLockRwsemFuncs(prefix, param, rwsem) \
+static inline void prefix##_read_lock(param) \
+{ down_read(rwsem); } \
+static inline void prefix##_write_lock(param) \
+{ down_write(rwsem); } \
+static inline int prefix##_read_trylock(param) \
+{ return down_read_trylock(rwsem); } \
+static inline int prefix##_write_trylock(param) \
+{ return down_write_trylock(rwsem); }
+/* why is not _nested version defined */
+/* static inline void prefix##_read_trylock_nested(param, lsc)
+{ down_write_trylock_nested(rwsem, lsc)); }
+static inline void prefix##_write_trylock_nestd(param, lsc)
+{ down_write_trylock_nested(rwsem, lsc); } */
+
+#define AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) \
+static inline void prefix##_read_unlock(param) \
+{ up_read(rwsem); } \
+static inline void prefix##_write_unlock(param) \
+{ up_write(rwsem); } \
+static inline void prefix##_downgrade_lock(param) \
+{ downgrade_write(rwsem); }
+
+#define AuSimpleRwsemFuncs(prefix, param, rwsem) \
+       AuSimpleLockRwsemFuncs(prefix, param, rwsem) \
+       AuSimpleUnlockRwsemFuncs(prefix, param, rwsem)
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_RWSEM_H__ */
diff --git a/fs/aufs/sbinfo.c b/fs/aufs/sbinfo.c
new file mode 100644
index 0000000..37e0649
--- /dev/null
+++ b/fs/aufs/sbinfo.c
@@ -0,0 +1,194 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * superblock private data
+ */
+
+#include "aufs.h"
+
+/*
+ * they are necessary regardless sysfs is disabled.
+ */
+void au_si_free(struct kobject *kobj)
+{
+       struct au_sbinfo *sbinfo;
+       struct super_block *sb;
+
+       sbinfo = container_of(kobj, struct au_sbinfo, si_kobj);
+       AuDebugOn(!list_empty(&sbinfo->si_plink.head));
+
+       sb = sbinfo->si_sb;
+       si_write_lock(sb);
+       au_xino_clr(sb);
+       au_br_free(sbinfo);
+       kfree(sbinfo->si_branch);
+       mutex_destroy(&sbinfo->si_xib_mtx);
+       si_write_unlock(sb);
+       au_rwsem_destroy(&sbinfo->si_rwsem);
+
+       kfree(sbinfo);
+}
+
+int au_si_alloc(struct super_block *sb)
+{
+       int err;
+       struct au_sbinfo *sbinfo;
+
+       err = -ENOMEM;
+       sbinfo = kmalloc(sizeof(*sbinfo), GFP_NOFS);
+       if (unlikely(!sbinfo))
+               goto out;
+
+       /* will be reallocated separately */
+       sbinfo->si_branch = kzalloc(sizeof(*sbinfo->si_branch), GFP_NOFS);
+       if (unlikely(!sbinfo->si_branch))
+               goto out_sbinfo;
+
+       memset(&sbinfo->si_kobj, 0, sizeof(sbinfo->si_kobj));
+       err = sysaufs_si_init(sbinfo);
+       if (unlikely(err))
+               goto out_br;
+
+       au_nwt_init(&sbinfo->si_nowait);
+       init_rwsem(&sbinfo->si_rwsem);
+       down_write(&sbinfo->si_rwsem);
+       sbinfo->si_generation = 0;
+       sbinfo->au_si_status = 0;
+       sbinfo->si_bend = -1;
+       sbinfo->si_last_br_id = 0;
+
+       sbinfo->si_wbr_copyup = AuWbrCopyup_Def;
+       sbinfo->si_wbr_create = AuWbrCreate_Def;
+       sbinfo->si_wbr_copyup_ops = au_wbr_copyup_ops + AuWbrCopyup_Def;
+       sbinfo->si_wbr_create_ops = au_wbr_create_ops + AuWbrCreate_Def;
+
+       sbinfo->si_mntflags = AuOpt_Def;
+
+       sbinfo->si_xread = NULL;
+       sbinfo->si_xwrite = NULL;
+       sbinfo->si_xib = NULL;
+       mutex_init(&sbinfo->si_xib_mtx);
+       sbinfo->si_xib_buf = NULL;
+       sbinfo->si_xino_brid = -1;
+       /* leave si_xib_last_pindex and si_xib_next_bit */
+
+       sbinfo->si_rdcache = AUFS_RDCACHE_DEF * HZ;
+       sbinfo->si_rdblk = AUFS_RDBLK_DEF;
+       sbinfo->si_rdhash = AUFS_RDHASH_DEF;
+       sbinfo->si_dirwh = AUFS_DIRWH_DEF;
+
+       au_spl_init(&sbinfo->si_plink);
+       init_waitqueue_head(&sbinfo->si_plink_wq);
+
+       /* leave other members for sysaufs and si_mnt. */
+       sbinfo->si_sb = sb;
+       sb->s_fs_info = sbinfo;
+       au_debug_sbinfo_init(sbinfo);
+       return 0; /* success */
+
+ out_br:
+       kfree(sbinfo->si_branch);
+ out_sbinfo:
+       kfree(sbinfo);
+ out:
+       return err;
+}
+
+int au_sbr_realloc(struct au_sbinfo *sbinfo, int nbr)
+{
+       int err, sz;
+       struct au_branch **brp;
+
+       err = -ENOMEM;
+       sz = sizeof(*brp) * (sbinfo->si_bend + 1);
+       if (unlikely(!sz))
+               sz = sizeof(*brp);
+       brp = au_kzrealloc(sbinfo->si_branch, sz, sizeof(*brp) * nbr, GFP_NOFS);
+       if (brp) {
+               sbinfo->si_branch = brp;
+               err = 0;
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+unsigned int au_sigen_inc(struct super_block *sb)
+{
+       unsigned int gen;
+
+       gen = ++au_sbi(sb)->si_generation;
+       au_update_digen(sb->s_root);
+       au_update_iigen(sb->s_root->d_inode);
+       sb->s_root->d_inode->i_version++;
+       return gen;
+}
+
+aufs_bindex_t au_new_br_id(struct super_block *sb)
+{
+       aufs_bindex_t br_id;
+       int i;
+       struct au_sbinfo *sbinfo;
+
+       sbinfo = au_sbi(sb);
+       for (i = 0; i <= AUFS_BRANCH_MAX; i++) {
+               br_id = ++sbinfo->si_last_br_id;
+               if (br_id && au_br_index(sb, br_id) < 0)
+                       return br_id;
+       }
+
+       return -1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* dentry and super_block lock. call at entry point */
+void aufs_read_lock(struct dentry *dentry, int flags)
+{
+       si_read_lock(dentry->d_sb, flags);
+       if (au_ftest_lock(flags, DW))
+               di_write_lock_child(dentry);
+       else
+               di_read_lock_child(dentry, flags);
+}
+
+void aufs_read_unlock(struct dentry *dentry, int flags)
+{
+       if (au_ftest_lock(flags, DW))
+               di_write_unlock(dentry);
+       else
+               di_read_unlock(dentry, flags);
+       si_read_unlock(dentry->d_sb);
+}
+
+void aufs_write_lock(struct dentry *dentry)
+{
+       si_write_lock(dentry->d_sb);
+       di_write_lock_child(dentry);
+}
+
+void aufs_write_unlock(struct dentry *dentry)
+{
+       di_write_unlock(dentry);
+       si_write_unlock(dentry->d_sb);
+}
+
+void aufs_read_and_write_lock2(struct dentry *d1, struct dentry *d2, int flags)
+{
+       si_read_lock(d1->d_sb, flags);
+       di_write_lock2_child(d1, d2, au_ftest_lock(flags, DIR));
+}
+
+void aufs_read_and_write_unlock2(struct dentry *d1, struct dentry *d2)
+{
+       di_write_unlock2(d1, d2);
+       si_read_unlock(d1->d_sb);
+}
diff --git a/fs/aufs/spl.h b/fs/aufs/spl.h
new file mode 100644
index 0000000..89ea7a2
--- /dev/null
+++ b/fs/aufs/spl.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * simple list protected by a spinlock
+ */
+
+#ifndef __AUFS_SPL_H__
+#define __AUFS_SPL_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+
+struct au_splhead {
+       spinlock_t              spin;
+       struct list_head        head;
+};
+
+static inline void au_spl_init(struct au_splhead *spl)
+{
+       spin_lock_init(&spl->spin);
+       INIT_LIST_HEAD(&spl->head);
+}
+
+static inline void au_spl_add(struct list_head *list, struct au_splhead *spl)
+{
+       spin_lock(&spl->spin);
+       list_add(list, &spl->head);
+       spin_unlock(&spl->spin);
+}
+
+static inline void au_spl_del(struct list_head *list, struct au_splhead *spl)
+{
+       spin_lock(&spl->spin);
+       list_del(list);
+       spin_unlock(&spl->spin);
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_SPL_H__ */
diff --git a/fs/aufs/super.c b/fs/aufs/super.c
new file mode 100644
index 0000000..0f6ad13
--- /dev/null
+++ b/fs/aufs/super.c
@@ -0,0 +1,859 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * mount and super_block operations
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/seq_file.h>
+#include <linux/statfs.h>
+#include "aufs.h"
+
+/*
+ * super_operations
+ */
+static struct inode *aufs_alloc_inode(struct super_block *sb __maybe_unused)
+{
+       struct au_icntnr *c;
+
+       c = au_cache_alloc_icntnr();
+       if (c) {
+               inode_init_once(&c->vfs_inode);
+               c->vfs_inode.i_version = 1; /* sigen(sb); */
+               c->iinfo.ii_hinode = NULL;
+               return &c->vfs_inode;
+       }
+       return NULL;
+}
+
+static void aufs_destroy_inode(struct inode *inode)
+{
+       au_iinfo_fin(inode);
+       au_cache_free_icntnr(container_of(inode, struct au_icntnr, vfs_inode));
+}
+
+struct inode *au_iget_locked(struct super_block *sb, ino_t ino)
+{
+       struct inode *inode;
+       int err;
+
+       inode = iget_locked(sb, ino);
+       if (unlikely(!inode)) {
+               inode = ERR_PTR(-ENOMEM);
+               goto out;
+       }
+       if (!(inode->i_state & I_NEW))
+               goto out;
+
+       err = au_xigen_new(inode);
+       if (!err)
+               err = au_iinfo_init(inode);
+       if (!err)
+               inode->i_version++;
+       else {
+               iget_failed(inode);
+               inode = ERR_PTR(err);
+       }
+
+ out:
+       /* never return NULL */
+       AuDebugOn(!inode);
+       AuTraceErrPtr(inode);
+       return inode;
+}
+
+/* lock free root dinfo */
+static int au_show_brs(struct seq_file *seq, struct super_block *sb)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       struct path path;
+       struct au_hdentry *hd;
+       struct au_branch *br;
+
+       err = 0;
+       bend = au_sbend(sb);
+       hd = au_di(sb->s_root)->di_hdentry;
+       for (bindex = 0; !err && bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               path.mnt = br->br_mnt;
+               path.dentry = hd[bindex].hd_dentry;
+               err = au_seq_path(seq, &path);
+               if (err > 0)
+                       err = seq_printf(seq, "=%s",
+                                        au_optstr_br_perm(br->br_perm));
+               if (!err && bindex != bend)
+                       err = seq_putc(seq, ':');
+       }
+
+       return err;
+}
+
+static void au_show_wbr_create(struct seq_file *m, int v,
+                              struct au_sbinfo *sbinfo)
+{
+       const char *pat;
+
+       seq_printf(m, ",create=");
+       pat = au_optstr_wbr_create(v);
+       switch (v) {
+       case AuWbrCreate_TDP:
+       case AuWbrCreate_RR:
+       case AuWbrCreate_MFS:
+       case AuWbrCreate_PMFS:
+               seq_printf(m, pat);
+               break;
+       case AuWbrCreate_MFSV:
+               seq_printf(m, /*pat*/"mfs:%lu",
+                          sbinfo->si_wbr_mfs.mfs_expire / HZ);
+               break;
+       case AuWbrCreate_PMFSV:
+               seq_printf(m, /*pat*/"pmfs:%lu",
+                          sbinfo->si_wbr_mfs.mfs_expire / HZ);
+               break;
+       case AuWbrCreate_MFSRR:
+               seq_printf(m, /*pat*/"mfsrr:%llu",
+                          sbinfo->si_wbr_mfs.mfsrr_watermark);
+               break;
+       case AuWbrCreate_MFSRRV:
+               seq_printf(m, /*pat*/"mfsrr:%llu:%lu",
+                          sbinfo->si_wbr_mfs.mfsrr_watermark,
+                          sbinfo->si_wbr_mfs.mfs_expire / HZ);
+               break;
+       }
+}
+
+static int au_show_xino(struct seq_file *seq, struct vfsmount *mnt)
+{
+#ifdef CONFIG_SYSFS
+       return 0;
+#else
+       int err;
+       const int len = sizeof(AUFS_XINO_FNAME) - 1;
+       aufs_bindex_t bindex, brid;
+       struct super_block *sb;
+       struct qstr *name;
+       struct file *f;
+       struct dentry *d, *h_root;
+
+       err = 0;
+       sb = mnt->mnt_sb;
+       f = au_sbi(sb)->si_xib;
+       if (!f)
+               goto out;
+
+       /* stop printing the default xino path on the first writable branch */
+       h_root = NULL;
+       brid = au_xino_brid(sb);
+       if (brid >= 0) {
+               bindex = au_br_index(sb, brid);
+               h_root = au_di(sb->s_root)->di_hdentry[0 + bindex].hd_dentry;
+       }
+       d = f->f_dentry;
+       name = &d->d_name;
+       /* safe ->d_parent because the file is unlinked */
+       if (d->d_parent == h_root
+           && name->len == len
+           && !memcmp(name->name, AUFS_XINO_FNAME, len))
+               goto out;
+
+       seq_puts(seq, ",xino=");
+       err = au_xino_path(seq, f);
+
+ out:
+       return err;
+#endif
+}
+
+/* seq_file will re-call me in case of too long string */
+static int aufs_show_options(struct seq_file *m, struct vfsmount *mnt)
+{
+       int err, n;
+       unsigned int mnt_flags, v;
+       struct super_block *sb;
+       struct au_sbinfo *sbinfo;
+
+#define AuBool(name, str) do { \
+       v = au_opt_test(mnt_flags, name); \
+       if (v != au_opt_test(AuOpt_Def, name)) \
+               seq_printf(m, ",%s" #str, v ? "" : "no"); \
+} while (0)
+
+#define AuStr(name, str) do { \
+       v = mnt_flags & AuOptMask_##name; \
+       if (v != (AuOpt_Def & AuOptMask_##name)) \
+               seq_printf(m, "," #str "=%s", au_optstr_##str(v)); \
+} while (0)
+
+#define AuUInt(name, str, val) do { \
+       if (val != AUFS_##name##_DEF) \
+               seq_printf(m, "," #str "=%u", val); \
+} while (0)
+
+       /* lock free root dinfo */
+       sb = mnt->mnt_sb;
+       si_noflush_read_lock(sb);
+       sbinfo = au_sbi(sb);
+       seq_printf(m, ",si=%lx", sysaufs_si_id(sbinfo));
+
+       mnt_flags = au_mntflags(sb);
+       if (au_opt_test(mnt_flags, XINO)) {
+               err = au_show_xino(m, mnt);
+               if (unlikely(err))
+                       goto out;
+       } else
+               seq_puts(m, ",noxino");
+
+       AuBool(TRUNC_XINO, trunc_xino);
+       AuStr(UDBA, udba);
+       AuBool(PLINK, plink);
+       /* AuBool(DIRPERM1, dirperm1); */
+       /* AuBool(REFROF, refrof); */
+
+       v = sbinfo->si_wbr_create;
+       if (v != AuWbrCreate_Def)
+               au_show_wbr_create(m, v, sbinfo);
+
+       v = sbinfo->si_wbr_copyup;
+       if (v != AuWbrCopyup_Def)
+               seq_printf(m, ",cpup=%s", au_optstr_wbr_copyup(v));
+
+       v = au_opt_test(mnt_flags, ALWAYS_DIROPQ);
+       if (v != au_opt_test(AuOpt_Def, ALWAYS_DIROPQ))
+               seq_printf(m, ",diropq=%c", v ? 'a' : 'w');
+
+       AuUInt(DIRWH, dirwh, sbinfo->si_dirwh);
+
+       n = sbinfo->si_rdcache / HZ;
+       AuUInt(RDCACHE, rdcache, n);
+
+       AuUInt(RDBLK, rdblk, sbinfo->si_rdblk);
+       AuUInt(RDHASH, rdhash, sbinfo->si_rdhash);
+
+       AuBool(SUM, sum);
+       /* AuBool(SUM_W, wsum); */
+       AuBool(WARN_PERM, warn_perm);
+       AuBool(VERBOSE, verbose);
+
+ out:
+       /* be sure to print "br:" last */
+       if (!sysaufs_brs) {
+               seq_puts(m, ",br:");
+               au_show_brs(m, sb);
+       }
+       si_read_unlock(sb);
+       return 0;
+
+#undef Deleted
+#undef AuBool
+#undef AuStr
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* sum mode which returns the summation for statfs(2) */
+
+static u64 au_add_till_max(u64 a, u64 b)
+{
+       u64 old;
+
+       old = a;
+       a += b;
+       if (old < a)
+               return a;
+       return ULLONG_MAX;
+}
+
+static int au_statfs_sum(struct super_block *sb, struct kstatfs *buf)
+{
+       int err;
+       u64 blocks, bfree, bavail, files, ffree;
+       aufs_bindex_t bend, bindex, i;
+       unsigned char shared;
+       struct vfsmount *h_mnt;
+       struct super_block *h_sb;
+
+       blocks = 0;
+       bfree = 0;
+       bavail = 0;
+       files = 0;
+       ffree = 0;
+
+       err = 0;
+       bend = au_sbend(sb);
+       for (bindex = bend; bindex >= 0; bindex--) {
+               h_mnt = au_sbr_mnt(sb, bindex);
+               h_sb = h_mnt->mnt_sb;
+               shared = 0;
+               for (i = bindex + 1; !shared && i <= bend; i++)
+                       shared = (au_sbr_sb(sb, i) == h_sb);
+               if (shared)
+                       continue;
+
+               /* sb->s_root for NFS is unreliable */
+               err = vfs_statfs(h_mnt->mnt_root, buf);
+               if (unlikely(err))
+                       goto out;
+
+               blocks = au_add_till_max(blocks, buf->f_blocks);
+               bfree = au_add_till_max(bfree, buf->f_bfree);
+               bavail = au_add_till_max(bavail, buf->f_bavail);
+               files = au_add_till_max(files, buf->f_files);
+               ffree = au_add_till_max(ffree, buf->f_ffree);
+       }
+
+       buf->f_blocks = blocks;
+       buf->f_bfree = bfree;
+       buf->f_bavail = bavail;
+       buf->f_files = files;
+       buf->f_ffree = ffree;
+
+ out:
+       return err;
+}
+
+static int aufs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+       int err;
+       struct super_block *sb;
+
+       /* lock free root dinfo */
+       sb = dentry->d_sb;
+       si_noflush_read_lock(sb);
+       if (!au_opt_test(au_mntflags(sb), SUM))
+               /* sb->s_root for NFS is unreliable */
+               err = vfs_statfs(au_sbr_mnt(sb, 0)->mnt_root, buf);
+       else
+               err = au_statfs_sum(sb, buf);
+       si_read_unlock(sb);
+
+       if (!err) {
+               buf->f_type = AUFS_SUPER_MAGIC;
+               buf->f_namelen -= AUFS_WH_PFX_LEN;
+               memset(&buf->f_fsid, 0, sizeof(buf->f_fsid));
+       }
+       /* buf->f_bsize = buf->f_blocks = buf->f_bfree = buf->f_bavail = -1; */
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* try flushing the lower fs at aufs remount/unmount time */
+
+static void au_fsync_br(struct super_block *sb)
+{
+       aufs_bindex_t bend, bindex;
+       int brperm;
+       struct au_branch *br;
+       struct super_block *h_sb;
+
+       bend = au_sbend(sb);
+       for (bindex = 0; bindex < bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               brperm = br->br_perm;
+               if (brperm == AuBrPerm_RR || brperm == AuBrPerm_RRWH)
+                       continue;
+               h_sb = br->br_mnt->mnt_sb;
+               if (bdev_read_only(h_sb->s_bdev))
+                       continue;
+
+               lockdep_off();
+               down_write(&h_sb->s_umount);
+               shrink_dcache_sb(h_sb);
+               fsync_super(h_sb);
+               up_write(&h_sb->s_umount);
+               lockdep_on();
+       }
+}
+
+/*
+ * this IS NOT for super_operations.
+ * I guess it will be reverted someday.
+ */
+static void aufs_umount_begin(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+
+       sbinfo = au_sbi(sb);
+       if (!sbinfo)
+               return;
+
+       si_write_lock(sb);
+       au_fsync_br(sb);
+       if (au_opt_test(au_mntflags(sb), PLINK))
+               au_plink_put(sb);
+       if (sbinfo->si_wbr_create_ops->fin)
+               sbinfo->si_wbr_create_ops->fin(sb);
+       si_write_unlock(sb);
+}
+
+/* final actions when unmounting a file system */
+static void aufs_put_super(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+
+       sbinfo = au_sbi(sb);
+       if (!sbinfo)
+               return;
+
+       aufs_umount_begin(sb);
+       dbgaufs_si_fin(sbinfo);
+       kobject_put(&sbinfo->si_kobj);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * refresh dentry and inode at remount time.
+ */
+static int do_refresh(struct dentry *dentry, mode_t type,
+                     unsigned int dir_flags)
+{
+       int err;
+       struct dentry *parent;
+
+       di_write_lock_child(dentry);
+       parent = dget_parent(dentry);
+       di_read_lock_parent(parent, AuLock_IR);
+
+       /* returns the number of positive dentries */
+       err = au_refresh_hdentry(dentry, type);
+       if (err >= 0) {
+               struct inode *inode = dentry->d_inode;
+               err = au_refresh_hinode(inode, dentry);
+               if (!err && type == S_IFDIR)
+                       au_reset_hinotify(inode, dir_flags);
+       }
+       if (unlikely(err))
+               AuErr("unrecoverable error %d, %.*s\n", err, AuDLNPair(dentry));
+
+       di_read_unlock(parent, AuLock_IR);
+       dput(parent);
+       di_write_unlock(dentry);
+
+       return err;
+}
+
+static int test_dir(struct dentry *dentry, void *arg __maybe_unused)
+{
+       return S_ISDIR(dentry->d_inode->i_mode);
+}
+
+/* gave up consolidating with refresh_nondir() */
+static int refresh_dir(struct dentry *root, unsigned int sigen)
+{
+       int err, i, j, ndentry, e;
+       struct au_dcsub_pages dpages;
+       struct au_dpage *dpage;
+       struct dentry **dentries;
+       struct inode *inode;
+       const unsigned int flags = au_hi_flags(root->d_inode, /*isdir*/1);
+
+       err = 0;
+       list_for_each_entry(inode, &root->d_sb->s_inodes, i_sb_list)
+               if (S_ISDIR(inode->i_mode) && au_iigen(inode) != sigen) {
+                       ii_write_lock_child(inode);
+                       e = au_refresh_hinode_self(inode, /*do_attr*/1);
+                       ii_write_unlock(inode);
+                       if (unlikely(e)) {
+                               AuDbg("e %d, i%lu\n", e, inode->i_ino);
+                               if (!err)
+                                       err = e;
+                               /* go on even if err */
+                       }
+               }
+
+       e = au_dpages_init(&dpages, GFP_NOFS);
+       if (unlikely(e)) {
+               if (!err)
+                       err = e;
+               goto out;
+       }
+       e = au_dcsub_pages(&dpages, root, test_dir, NULL);
+       if (unlikely(e)) {
+               if (!err)
+                       err = e;
+               goto out_dpages;
+       }
+
+       for (i = 0; !e && i < dpages.ndpage; i++) {
+               dpage = dpages.dpages + i;
+               dentries = dpage->dentries;
+               ndentry = dpage->ndentry;
+               for (j = 0; !e && j < ndentry; j++) {
+                       struct dentry *d;
+
+                       d = dentries[j];
+                       au_dbg_verify_dir_parent(d, sigen);
+                       if (au_digen(d) != sigen) {
+                               e = do_refresh(d, S_IFDIR, flags);
+                               if (unlikely(e && !err))
+                                       err = e;
+                               /* break on err */
+                       }
+               }
+       }
+
+ out_dpages:
+       au_dpages_free(&dpages);
+ out:
+       return err;
+}
+
+static int test_nondir(struct dentry *dentry, void *arg __maybe_unused)
+{
+       return !S_ISDIR(dentry->d_inode->i_mode);
+}
+
+static int refresh_nondir(struct dentry *root, unsigned int sigen,
+                         int do_dentry)
+{
+       int err, i, j, ndentry, e;
+       struct au_dcsub_pages dpages;
+       struct au_dpage *dpage;
+       struct dentry **dentries;
+       struct inode *inode;
+
+       err = 0;
+       list_for_each_entry(inode, &root->d_sb->s_inodes, i_sb_list)
+               if (!S_ISDIR(inode->i_mode) && au_iigen(inode) != sigen) {
+                       ii_write_lock_child(inode);
+                       e = au_refresh_hinode_self(inode, /*do_attr*/1);
+                       ii_write_unlock(inode);
+                       if (unlikely(e)) {
+                               AuDbg("e %d, i%lu\n", e, inode->i_ino);
+                               if (!err)
+                                       err = e;
+                               /* go on even if err */
+                       }
+               }
+
+       if (!do_dentry)
+               goto out;
+
+       e = au_dpages_init(&dpages, GFP_NOFS);
+       if (unlikely(e)) {
+               if (!err)
+                       err = e;
+               goto out;
+       }
+       e = au_dcsub_pages(&dpages, root, test_nondir, NULL);
+       if (unlikely(e)) {
+               if (!err)
+                       err = e;
+               goto out_dpages;
+       }
+
+       for (i = 0; i < dpages.ndpage; i++) {
+               dpage = dpages.dpages + i;
+               dentries = dpage->dentries;
+               ndentry = dpage->ndentry;
+               for (j = 0; j < ndentry; j++) {
+                       struct dentry *d;
+
+                       d = dentries[j];
+                       au_dbg_verify_nondir_parent(d, sigen);
+                       inode = d->d_inode;
+                       if (inode && au_digen(d) != sigen) {
+                               e = do_refresh(d, inode->i_mode & S_IFMT,
+                                              /*dir_flags*/0);
+                               if (unlikely(e && !err))
+                                       err = e;
+                               /* go on even err */
+                       }
+               }
+       }
+
+ out_dpages:
+       au_dpages_free(&dpages);
+ out:
+       return err;
+}
+
+static void au_remount_refresh(struct super_block *sb, unsigned int flags)
+{
+       int err;
+       unsigned int sigen;
+       struct au_sbinfo *sbinfo;
+       struct dentry *root;
+       struct inode *inode;
+
+       au_sigen_inc(sb);
+       sigen = au_sigen(sb);
+       sbinfo = au_sbi(sb);
+       au_fclr_si(sbinfo, FAILED_REFRESH_DIRS);
+
+       root = sb->s_root;
+       DiMustNoWaiters(root);
+       inode = root->d_inode;
+       IiMustNoWaiters(inode);
+       au_reset_hinotify(inode, au_hi_flags(inode, /*isdir*/1));
+       di_write_unlock(root);
+
+       err = refresh_dir(root, sigen);
+       if (unlikely(err)) {
+               au_fset_si(sbinfo, FAILED_REFRESH_DIRS);
+               AuWarn("Refreshing directories failed, ignored (%d)\n", err);
+       }
+
+       if (au_ftest_opts(flags, REFRESH_NONDIR)) {
+               err = refresh_nondir(root, sigen, !err);
+               if (unlikely(err))
+                       AuWarn("Refreshing non-directories failed, ignored"
+                              "(%d)\n", err);
+       }
+
+       /* aufs_write_lock() calls ..._child() */
+       di_write_lock_child(root);
+       au_cpup_attr_all(root->d_inode, /*force*/1);
+}
+
+/* stop extra interpretation of errno in mount(8), and strange error messages */
+static int cvt_err(int err)
+{
+       AuTraceErr(err);
+
+       switch (err) {
+       case -ENOENT:
+       case -ENOTDIR:
+       case -EEXIST:
+       case -EIO:
+               err = -EINVAL;
+       }
+       return err;
+}
+
+static int aufs_remount_fs(struct super_block *sb, int *flags, char *data)
+{
+       int err;
+       struct au_opts opts;
+       struct dentry *root;
+       struct inode *inode;
+       struct au_sbinfo *sbinfo;
+
+       err = 0;
+       root = sb->s_root;
+       if (!data || !*data) {
+               aufs_write_lock(root);
+               err = au_opts_verify(sb, *flags, /*pending*/0);
+               if (!err)
+                       au_fsync_br(sb);
+               aufs_write_unlock(root);
+               goto out;
+       }
+
+       err = -ENOMEM;
+       memset(&opts, 0, sizeof(opts));
+       opts.opt = (void *)__get_free_page(GFP_NOFS);
+       if (unlikely(!opts.opt))
+               goto out;
+       opts.max_opt = PAGE_SIZE / sizeof(*opts.opt);
+       opts.flags = AuOpts_REMOUNT;
+       opts.sb_flags = *flags;
+
+       /* parse it before aufs lock */
+       err = au_opts_parse(sb, data, &opts);
+       if (unlikely(err))
+               goto out_opts;
+
+       sbinfo = au_sbi(sb);
+       inode = root->d_inode;
+       mutex_lock(&inode->i_mutex);
+       aufs_write_lock(root);
+       au_fsync_br(sb);
+
+       /* au_opts_remount() may return an error */
+       err = au_opts_remount(sb, &opts);
+       au_opts_free(&opts);
+
+       if (au_ftest_opts(opts.flags, REFRESH_DIR)
+           || au_ftest_opts(opts.flags, REFRESH_NONDIR))
+               au_remount_refresh(sb, opts.flags);
+
+       aufs_write_unlock(root);
+       mutex_unlock(&inode->i_mutex);
+
+ out_opts:
+       free_page((unsigned long)opts.opt);
+ out:
+       err = cvt_err(err);
+       AuTraceErr(err);
+       return err;
+}
+
+static struct super_operations aufs_sop = {
+       .alloc_inode    = aufs_alloc_inode,
+       .destroy_inode  = aufs_destroy_inode,
+       .drop_inode     = generic_delete_inode,
+       .show_options   = aufs_show_options,
+       .statfs         = aufs_statfs,
+       .put_super      = aufs_put_super,
+       .remount_fs     = aufs_remount_fs
+};
+
+/* ---------------------------------------------------------------------- */
+
+static int alloc_root(struct super_block *sb)
+{
+       int err;
+       struct inode *inode;
+       struct dentry *root;
+
+       err = -ENOMEM;
+       inode = au_iget_locked(sb, AUFS_ROOT_INO);
+       err = PTR_ERR(inode);
+       if (IS_ERR(inode))
+               goto out;
+
+       inode->i_op = &aufs_dir_iop;
+       inode->i_fop = &aufs_dir_fop;
+       inode->i_mode = S_IFDIR;
+       inode->i_nlink = 2;
+       unlock_new_inode(inode);
+
+       root = d_alloc_root(inode);
+       if (unlikely(!root))
+               goto out_iput;
+       err = PTR_ERR(root);
+       if (IS_ERR(root))
+               goto out_iput;
+
+       err = au_alloc_dinfo(root);
+       if (!err) {
+               sb->s_root = root;
+               return 0; /* success */
+       }
+       dput(root);
+       goto out; /* do not iput */
+
+ out_iput:
+       iget_failed(inode);
+       iput(inode);
+ out:
+       return err;
+
+}
+
+static int aufs_fill_super(struct super_block *sb, void *raw_data,
+                          int silent __maybe_unused)
+{
+       int err;
+       struct au_opts opts;
+       struct dentry *root;
+       struct inode *inode;
+       char *arg = raw_data;
+
+       if (unlikely(!arg || !*arg)) {
+               err = -EINVAL;
+               AuErr("no arg\n");
+               goto out;
+       }
+
+       err = -ENOMEM;
+       memset(&opts, 0, sizeof(opts));
+       opts.opt = (void *)__get_free_page(GFP_NOFS);
+       if (unlikely(!opts.opt))
+               goto out;
+       opts.max_opt = PAGE_SIZE / sizeof(*opts.opt);
+       opts.sb_flags = sb->s_flags;
+
+       err = au_si_alloc(sb);
+       if (unlikely(err))
+               goto out_opts;
+
+       /* all timestamps always follow the ones on the branch */
+       sb->s_flags |= MS_NOATIME | MS_NODIRATIME;
+       sb->s_op = &aufs_sop;
+       sb->s_magic = AUFS_SUPER_MAGIC;
+       sb->s_maxbytes = 0;
+       au_export_init(sb);
+
+       err = alloc_root(sb);
+       if (unlikely(err)) {
+               si_write_unlock(sb);
+               goto out_info;
+       }
+       root = sb->s_root;
+       inode = root->d_inode;
+
+       /*
+        * actually we can parse options regardless aufs lock here.
+        * but at remount time, parsing must be done before aufs lock.
+        * so we follow the same rule.
+        */
+       ii_write_lock_parent(inode);
+       aufs_write_unlock(root);
+       err = au_opts_parse(sb, arg, &opts);
+       if (unlikely(err))
+               goto out_root;
+
+       /* lock vfs_inode first, then aufs. */
+       mutex_lock(&inode->i_mutex);
+       inode->i_op = &aufs_dir_iop;
+       inode->i_fop = &aufs_dir_fop;
+       aufs_write_lock(root);
+       err = au_opts_mount(sb, &opts);
+       au_opts_free(&opts);
+       if (unlikely(err))
+               goto out_unlock;
+       aufs_write_unlock(root);
+       mutex_unlock(&inode->i_mutex);
+       goto out_opts; /* success */
+
+ out_unlock:
+       aufs_write_unlock(root);
+       mutex_unlock(&inode->i_mutex);
+ out_root:
+       dput(root);
+       sb->s_root = NULL;
+ out_info:
+       kobject_put(&au_sbi(sb)->si_kobj);
+       sb->s_fs_info = NULL;
+ out_opts:
+       free_page((unsigned long)opts.opt);
+ out:
+       AuTraceErr(err);
+       err = cvt_err(err);
+       AuTraceErr(err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int aufs_get_sb(struct file_system_type *fs_type, int flags,
+                      const char *dev_name __maybe_unused, void *raw_data,
+                      struct vfsmount *mnt)
+{
+       int err;
+       struct super_block *sb;
+
+       /* all timestamps always follow the ones on the branch */
+       /* mnt->mnt_flags |= MNT_NOATIME | MNT_NODIRATIME; */
+       err = get_sb_nodev(fs_type, flags, raw_data, aufs_fill_super, mnt);
+       if (!err) {
+               sb = mnt->mnt_sb;
+               si_write_lock(sb);
+               sysaufs_brs_add(sb, 0);
+               si_write_unlock(sb);
+       }
+       return err;
+}
+
+struct file_system_type aufs_fs_type = {
+       .name           = AUFS_FSTYPE,
+       .fs_flags       =
+               FS_RENAME_DOES_D_MOVE   /* a race between rename and others */
+               | FS_REVAL_DOT,         /* for NFS branch and udba */
+       .get_sb         = aufs_get_sb,
+       .kill_sb        = generic_shutdown_super,
+       /* no need to __module_get() and module_put(). */
+       .owner          = THIS_MODULE,
+};
diff --git a/fs/aufs/super.h b/fs/aufs/super.h
new file mode 100644
index 0000000..9897dba
--- /dev/null
+++ b/fs/aufs/super.h
@@ -0,0 +1,351 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * super_block operations
+ */
+
+#ifndef __AUFS_SUPER_H__
+#define __AUFS_SUPER_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/kobject.h>
+#include <linux/aufs_type.h>
+#include "rwsem.h"
+#include "spl.h"
+#include "wkq.h"
+
+typedef ssize_t (*au_readf_t)(struct file *, char __user *, size_t, loff_t *);
+typedef ssize_t (*au_writef_t)(struct file *, const char __user *, size_t,
+                              loff_t *);
+
+/* policies to select one among multiple writable branches */
+struct au_wbr_copyup_operations {
+       int (*copyup)(struct dentry *dentry);
+};
+
+struct au_wbr_create_operations {
+       int (*create)(struct dentry *dentry, int isdir);
+       int (*init)(struct super_block *sb);
+       int (*fin)(struct super_block *sb);
+};
+
+struct au_wbr_mfs {
+       struct mutex    mfs_lock; /* protect this structure */
+       unsigned long   mfs_jiffy;
+       unsigned long   mfs_expire;
+       aufs_bindex_t   mfs_bindex;
+
+       unsigned long long      mfsrr_bytes;
+       unsigned long long      mfsrr_watermark;
+};
+
+/* sbinfo status flags */
+/*
+ * set true when refresh_dirs() failed at remount time.
+ * then try refreshing dirs at access time again.
+ * if it is false, refreshing dirs at access time is unnecesary
+ */
+#define AuSi_FAILED_REFRESH_DIRS       1
+#define AuSi_MAINTAIN_PLINK            (1 << 1)        /* ioctl */
+#define au_ftest_si(sbinfo, name)      ((sbinfo)->au_si_status & AuSi_##name)
+#define au_fset_si(sbinfo, name) \
+       { (sbinfo)->au_si_status |= AuSi_##name; }
+#define au_fclr_si(sbinfo, name) \
+       { (sbinfo)->au_si_status &= ~AuSi_##name; }
+
+struct au_branch;
+struct au_sbinfo {
+       /* nowait tasks in the system-wide workqueue */
+       struct au_nowait_tasks  si_nowait;
+
+       struct rw_semaphore     si_rwsem;
+
+       /* branch management */
+       unsigned int            si_generation;
+
+       /* see above flags */
+       unsigned char           au_si_status;
+
+       aufs_bindex_t           si_bend;
+       aufs_bindex_t           si_last_br_id;
+       struct au_branch        **si_branch;
+
+       /* policy to select a writable branch */
+       unsigned char           si_wbr_copyup;
+       unsigned char           si_wbr_create;
+       struct au_wbr_copyup_operations *si_wbr_copyup_ops;
+       struct au_wbr_create_operations *si_wbr_create_ops;
+
+       /* round robin */
+       atomic_t                si_wbr_rr_next;
+
+       /* most free space */
+       struct au_wbr_mfs       si_wbr_mfs;
+
+       /* mount flags */
+       /* include/asm-ia64/siginfo.h defines a macro named si_flags */
+       unsigned int            si_mntflags;
+
+       /* external inode number (bitmap and translation table) */
+       au_readf_t              si_xread;
+       au_writef_t             si_xwrite;
+       struct file             *si_xib;
+       struct mutex            si_xib_mtx; /* protect xib members */
+       unsigned long           *si_xib_buf;
+       unsigned long           si_xib_last_pindex;
+       int                     si_xib_next_bit;
+       aufs_bindex_t           si_xino_brid;
+       /* reserved for future use */
+       /* unsigned long long   si_xib_limit; */        /* Max xib file size */
+
+#ifdef CONFIG_AUFS_EXPORT
+       /* i_generation */
+       struct file             *si_xigen;
+       atomic_t                si_xigen_next;
+#endif
+
+       /* vdir parameters */
+       unsigned long           si_rdcache;     /* max cache time in HZ */
+       unsigned int            si_rdblk;       /* deblk size */
+       unsigned int            si_rdhash;      /* hash size */
+
+       /*
+        * If the number of whiteouts are larger than si_dirwh, leave all of
+        * them after au_whtmp_ren to reduce the cost of rmdir(2).
+        * future fsck.aufs or kernel thread will remove them later.
+        * Otherwise, remove all whiteouts and the dir in rmdir(2).
+        */
+       unsigned int            si_dirwh;
+
+       /*
+        * rename(2) a directory with all children.
+        */
+       /* reserved for future use */
+       /* int                  si_rendir; */
+
+       /* pseudo_link list */
+       struct au_splhead       si_plink;
+       wait_queue_head_t       si_plink_wq;
+
+       /*
+        * sysfs and lifetime management.
+        * this is not a small structure and it may be a waste of memory in case
+        * of sysfs is disabled, particulary when many aufs-es are mounted.
+        * but using sysfs is majority.
+        */
+       struct kobject          si_kobj;
+#ifdef CONFIG_DEBUG_FS
+       struct dentry            *si_dbgaufs, *si_dbgaufs_xib;
+#ifdef CONFIG_AUFS_EXPORT
+       struct dentry            *si_dbgaufs_xigen;
+#endif
+#endif
+
+       /* dirty, necessary for unmounting, sysfs and sysrq */
+       struct super_block      *si_sb;
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* policy to select one among writable branches */
+#define AuWbrCopyup(sbinfo, args...) \
+       ((sbinfo)->si_wbr_copyup_ops->copyup(args))
+#define AuWbrCreate(sbinfo, args...) \
+       ((sbinfo)->si_wbr_create_ops->create(args))
+
+/* flags for si_read_lock()/aufs_read_lock()/di_read_lock() */
+#define AuLock_DW              1               /* write-lock dentry */
+#define AuLock_IR              (1 << 1)        /* read-lock inode */
+#define AuLock_IW              (1 << 2)        /* write-lock inode */
+#define AuLock_FLUSH           (1 << 3)        /* wait for 'nowait' tasks */
+#define AuLock_DIR             (1 << 4)        /* target is a dir */
+#define au_ftest_lock(flags, name)     ((flags) & AuLock_##name)
+#define au_fset_lock(flags, name)      { (flags) |= AuLock_##name; }
+#define au_fclr_lock(flags, name)      { (flags) &= ~AuLock_##name; }
+
+/* ---------------------------------------------------------------------- */
+
+/* super.c */
+extern struct file_system_type aufs_fs_type;
+struct inode *au_iget_locked(struct super_block *sb, ino_t ino);
+
+/* sbinfo.c */
+void au_si_free(struct kobject *kobj);
+int au_si_alloc(struct super_block *sb);
+int au_sbr_realloc(struct au_sbinfo *sbinfo, int nbr);
+
+unsigned int au_sigen_inc(struct super_block *sb);
+aufs_bindex_t au_new_br_id(struct super_block *sb);
+
+void aufs_read_lock(struct dentry *dentry, int flags);
+void aufs_read_unlock(struct dentry *dentry, int flags);
+void aufs_write_lock(struct dentry *dentry);
+void aufs_write_unlock(struct dentry *dentry);
+void aufs_read_and_write_lock2(struct dentry *d1, struct dentry *d2, int isdir);
+void aufs_read_and_write_unlock2(struct dentry *d1, struct dentry *d2);
+
+/* wbr_policy.c */
+extern struct au_wbr_copyup_operations au_wbr_copyup_ops[];
+extern struct au_wbr_create_operations au_wbr_create_ops[];
+int au_cpdown_dirs(struct dentry *dentry, aufs_bindex_t bdst);
+
+/* ---------------------------------------------------------------------- */
+
+static inline struct au_sbinfo *au_sbi(struct super_block *sb)
+{
+       return sb->s_fs_info;
+}
+
+/* ---------------------------------------------------------------------- */
+
+#ifdef CONFIG_AUFS_EXPORT
+void au_export_init(struct super_block *sb);
+
+static inline int au_test_nfsd(struct task_struct *tsk)
+{
+       return !tsk->mm && !strcmp(tsk->comm, "nfsd");
+}
+
+int au_xigen_inc(struct inode *inode);
+int au_xigen_new(struct inode *inode);
+int au_xigen_set(struct super_block *sb, struct file *base);
+void au_xigen_clr(struct super_block *sb);
+
+static inline int au_busy_or_stale(void)
+{
+       if (!au_test_nfsd(current))
+               return -EBUSY;
+       return -ESTALE;
+}
+#else
+static inline void au_export_init(struct super_block *sb)
+{
+       /* nothing */
+}
+
+static inline int au_test_nfsd(struct task_struct *tsk)
+{
+       return 0;
+}
+
+static inline int au_xigen_inc(struct inode *inode)
+{
+       return 0;
+}
+
+static inline int au_xigen_new(struct inode *inode)
+{
+       return 0;
+}
+
+static inline int au_xigen_set(struct super_block *sb, struct file *base)
+{
+       return 0;
+}
+
+static inline void au_xigen_clr(struct super_block *sb)
+{
+       /* empty */
+}
+
+static inline int au_busy_or_stale(void)
+{
+       return -EBUSY;
+}
+#endif /* CONFIG_AUFS_EXPORT */
+
+/* ---------------------------------------------------------------------- */
+
+static inline void dbgaufs_si_null(struct au_sbinfo *sbinfo)
+{
+#ifdef CONFIG_DEBUG_FS
+       sbinfo->si_dbgaufs = NULL;
+       sbinfo->si_dbgaufs_xib = NULL;
+#ifdef CONFIG_AUFS_EXPORT
+       sbinfo->si_dbgaufs_xigen = NULL;
+#endif
+#endif
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* lock superblock. mainly for entry point functions */
+/*
+ * si_noflush_read_lock, si_noflush_write_lock,
+ * si_read_unlock, si_write_unlock, si_downgrade_lock
+ */
+AuSimpleLockRwsemFuncs(si_noflush, struct super_block *sb,
+                      &au_sbi(sb)->si_rwsem);
+AuSimpleUnlockRwsemFuncs(si, struct super_block *sb, &au_sbi(sb)->si_rwsem);
+
+static inline void si_read_lock(struct super_block *sb, int flags)
+{
+       if (au_ftest_lock(flags, FLUSH))
+               au_nwt_flush(&au_sbi(sb)->si_nowait);
+       si_noflush_read_lock(sb);
+}
+
+static inline void si_write_lock(struct super_block *sb)
+{
+       au_nwt_flush(&au_sbi(sb)->si_nowait);
+       si_noflush_write_lock(sb);
+}
+
+static inline int si_read_trylock(struct super_block *sb, int flags)
+{
+       if (au_ftest_lock(flags, FLUSH))
+               au_nwt_flush(&au_sbi(sb)->si_nowait);
+       return si_noflush_read_trylock(sb);
+}
+
+static inline int si_write_trylock(struct super_block *sb, int flags)
+{
+       if (au_ftest_lock(flags, FLUSH))
+               au_nwt_flush(&au_sbi(sb)->si_nowait);
+       return si_noflush_write_trylock(sb);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static inline aufs_bindex_t au_sbend(struct super_block *sb)
+{
+       return au_sbi(sb)->si_bend;
+}
+
+static inline unsigned int au_mntflags(struct super_block *sb)
+{
+       return au_sbi(sb)->si_mntflags;
+}
+
+static inline unsigned int au_sigen(struct super_block *sb)
+{
+       return au_sbi(sb)->si_generation;
+}
+
+static inline struct au_branch *au_sbr(struct super_block *sb,
+                                      aufs_bindex_t bindex)
+{
+       return au_sbi(sb)->si_branch[0 + bindex];
+}
+
+static inline void au_xino_brid_set(struct super_block *sb, aufs_bindex_t brid)
+{
+       au_sbi(sb)->si_xino_brid = brid;
+}
+
+static inline aufs_bindex_t au_xino_brid(struct super_block *sb)
+{
+       return au_sbi(sb)->si_xino_brid;
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_SUPER_H__ */
diff --git a/fs/aufs/sysaufs.c b/fs/aufs/sysaufs.c
new file mode 100644
index 0000000..623f2e6
--- /dev/null
+++ b/fs/aufs/sysaufs.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sysfs interface and lifetime management
+ * they are necessary regardless sysfs is disabled.
+ */
+
+#include <linux/fs.h>
+#include <linux/random.h>
+#include <linux/sysfs.h>
+#include "aufs.h"
+
+unsigned long sysaufs_si_mask;
+struct kset *sysaufs_ket;
+
+#define AuSiAttr(_name) { \
+       .attr   = { .name = __stringify(_name), .mode = 0444 }, \
+       .show   = sysaufs_si_##_name,                           \
+}
+
+static struct sysaufs_si_attr sysaufs_si_attr_xi_path = AuSiAttr(xi_path);
+struct attribute *sysaufs_si_attrs[] = {
+       &sysaufs_si_attr_xi_path.attr,
+       NULL,
+};
+
+static struct sysfs_ops au_sbi_ops = {
+       .show   = sysaufs_si_show
+};
+
+static struct kobj_type au_sbi_ktype = {
+       .release        = au_si_free,
+       .sysfs_ops      = &au_sbi_ops,
+       .default_attrs  = sysaufs_si_attrs
+};
+
+/* ---------------------------------------------------------------------- */
+
+int sysaufs_si_init(struct au_sbinfo *sbinfo)
+{
+       int err;
+
+       sbinfo->si_kobj.kset = sysaufs_ket;
+       /* cf. sysaufs_name() */
+       err = kobject_init_and_add
+               (&sbinfo->si_kobj, &au_sbi_ktype, /*&sysaufs_ket->kobj*/NULL,
+                SysaufsSiNamePrefix "%lx", sysaufs_si_id(sbinfo));
+
+       dbgaufs_si_null(sbinfo);
+       if (!err) {
+               err = dbgaufs_si_init(sbinfo);
+               if (unlikely(err))
+                       kobject_put(&sbinfo->si_kobj);
+       }
+       return err;
+}
+
+void sysaufs_fin(void)
+{
+       dbgaufs_fin();
+       sysfs_remove_group(&sysaufs_ket->kobj, sysaufs_attr_group);
+       kset_unregister(sysaufs_ket);
+}
+
+int __init sysaufs_init(void)
+{
+       int err;
+
+       do {
+               get_random_bytes(&sysaufs_si_mask, sizeof(sysaufs_si_mask));
+       } while (!sysaufs_si_mask);
+
+       sysaufs_ket = kset_create_and_add(AUFS_NAME, NULL, fs_kobj);
+       err = PTR_ERR(sysaufs_ket);
+       if (IS_ERR(sysaufs_ket))
+               goto out;
+       err = sysfs_create_group(&sysaufs_ket->kobj, sysaufs_attr_group);
+       if (unlikely(err)) {
+               kset_unregister(sysaufs_ket);
+               goto out;
+       }
+
+       err = dbgaufs_init();
+       if (unlikely(err))
+               sysaufs_fin();
+ out:
+       return err;
+}
diff --git a/fs/aufs/sysaufs.h b/fs/aufs/sysaufs.h
new file mode 100644
index 0000000..c1202fa
--- /dev/null
+++ b/fs/aufs/sysaufs.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sysfs interface and mount lifetime management
+ */
+
+#ifndef __SYSAUFS_H__
+#define __SYSAUFS_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/sysfs.h>
+#include <linux/aufs_type.h>
+#include "module.h"
+
+struct sysaufs_si_attr {
+       struct attribute attr;
+       int (*show)(struct seq_file *seq, struct super_block *sb);
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* sysaufs.c */
+extern unsigned long sysaufs_si_mask;
+extern struct kset *sysaufs_ket;
+extern struct attribute *sysaufs_si_attrs[];
+int sysaufs_si_init(struct au_sbinfo *sbinfo);
+int __init sysaufs_init(void);
+void sysaufs_fin(void);
+
+/* ---------------------------------------------------------------------- */
+
+/* some people doesn't like to show a pointer in kernel */
+static inline unsigned long sysaufs_si_id(struct au_sbinfo *sbinfo)
+{
+       return sysaufs_si_mask ^ (unsigned long)sbinfo;
+}
+
+#define SysaufsSiNamePrefix    "si_"
+#define SysaufsSiNameLen       (sizeof(SysaufsSiNamePrefix) + 16)
+static inline void sysaufs_name(struct au_sbinfo *sbinfo, char *name)
+{
+       snprintf(name, SysaufsSiNameLen, SysaufsSiNamePrefix "%lx",
+                sysaufs_si_id(sbinfo));
+}
+
+struct au_branch;
+#ifdef CONFIG_SYSFS
+/* sysfs.c */
+extern struct attribute_group *sysaufs_attr_group;
+
+int sysaufs_si_xi_path(struct seq_file *seq, struct super_block *sb);
+ssize_t sysaufs_si_show(struct kobject *kobj, struct attribute *attr,
+                        char *buf);
+
+void sysaufs_br_init(struct au_branch *br);
+void sysaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex);
+void sysaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex);
+
+#define sysaufs_brs_init()     do {} while (0)
+
+#else
+#define sysaufs_attr_group     NULL
+
+static inline
+int sysaufs_si_xi_path(struct seq_file *seq, struct super_block *sb)
+{
+       return 0;
+}
+
+static inline
+ssize_t sysaufs_si_show(struct kobject *kobj, struct attribute *attr,
+                        char *buf)
+{
+       return 0;
+}
+
+static inline void sysaufs_br_init(struct au_branch *br)
+{
+       /* empty */
+}
+
+static inline void sysaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex)
+{
+       /* nothing */
+}
+
+static inline void sysaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex)
+{
+       /* nothing */
+}
+
+static inline void sysaufs_brs_init(void)
+{
+       sysaufs_brs = 0;
+}
+
+#endif /* CONFIG_SYSFS */
+
+#endif /* __KERNEL__ */
+#endif /* __SYSAUFS_H__ */
diff --git a/fs/aufs/sysfs.c b/fs/aufs/sysfs.c
new file mode 100644
index 0000000..496a2fc
--- /dev/null
+++ b/fs/aufs/sysfs.c
@@ -0,0 +1,198 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sysfs interface
+ */
+
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/sysfs.h>
+#include "aufs.h"
+
+static struct attribute *au_attr[] = {
+       NULL,   /* need to NULL terminate the list of attributes */
+};
+
+static struct attribute_group sysaufs_attr_group_body = {
+       .attrs = au_attr
+};
+
+struct attribute_group *sysaufs_attr_group = &sysaufs_attr_group_body;
+
+/* ---------------------------------------------------------------------- */
+
+int sysaufs_si_xi_path(struct seq_file *seq, struct super_block *sb)
+{
+       int err;
+
+       err = 0;
+       if (au_opt_test(au_mntflags(sb), XINO)) {
+               err = au_xino_path(seq, au_sbi(sb)->si_xib);
+               seq_putc(seq, '\n');
+       }
+       return err;
+}
+
+/*
+ * the lifetime of branch is independent from the entry under sysfs.
+ * sysfs handles the lifetime of the entry, and never call ->show() after it is
+ * unlinked.
+ */
+static int sysaufs_si_br(struct seq_file *seq, struct super_block *sb,
+                        aufs_bindex_t bindex)
+{
+       struct path path;
+       struct dentry *root;
+       struct au_branch *br;
+
+       AuDbg("b%d\n", bindex);
+
+       root = sb->s_root;
+       di_read_lock_parent(root, !AuLock_IR);
+       br = au_sbr(sb, bindex);
+       path.mnt = br->br_mnt;
+       path.dentry = au_h_dptr(root, bindex);
+       au_seq_path(seq, &path);
+       di_read_unlock(root, !AuLock_IR);
+       seq_printf(seq, "=%s\n", au_optstr_br_perm(br->br_perm));
+       return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct seq_file *au_seq(char *p, ssize_t len)
+{
+       struct seq_file *seq;
+
+       seq = kzalloc(sizeof(*seq), GFP_NOFS);
+       if (seq) {
+               /* mutex_init(&seq.lock); */
+               seq->buf = p;
+               seq->size = len;
+               return seq; /* success */
+       }
+
+       seq = ERR_PTR(-ENOMEM);
+       return seq;
+}
+
+#define SysaufsBr_PREFIX "br"
+
+/* todo: file size may exceed PAGE_SIZE */
+ssize_t sysaufs_si_show(struct kobject *kobj, struct attribute *attr,
+                        char *buf)
+{
+       ssize_t err;
+       long l;
+       aufs_bindex_t bend;
+       struct au_sbinfo *sbinfo;
+       struct super_block *sb;
+       struct seq_file *seq;
+       char *name;
+       struct attribute **cattr;
+
+       sbinfo = container_of(kobj, struct au_sbinfo, si_kobj);
+       sb = sbinfo->si_sb;
+       si_noflush_read_lock(sb);
+
+       seq = au_seq(buf, PAGE_SIZE);
+       err = PTR_ERR(seq);
+       if (IS_ERR(seq))
+               goto out;
+
+       name = (void *)attr->name;
+       cattr = sysaufs_si_attrs;
+       while (*cattr) {
+               if (!strcmp(name, (*cattr)->name)) {
+                       err = container_of(*cattr, struct sysaufs_si_attr, attr)
+                               ->show(seq, sb);
+                       goto out_seq;
+               }
+               cattr++;
+       }
+
+       bend = au_sbend(sb);
+       if (!strncmp(name, SysaufsBr_PREFIX, sizeof(SysaufsBr_PREFIX) - 1)) {
+               name += sizeof(SysaufsBr_PREFIX) - 1;
+               err = strict_strtol(name, 10, &l);
+               if (!err) {
+                       if (l <= bend)
+                               err = sysaufs_si_br(seq, sb, (aufs_bindex_t)l);
+                       else
+                               err = -ENOENT;
+               }
+               goto out_seq;
+       }
+       BUG();
+
+ out_seq:
+       if (!err) {
+               err = seq->count;
+               /* sysfs limit */
+               if (unlikely(err == PAGE_SIZE))
+                       err = -EFBIG;
+       }
+       kfree(seq);
+ out:
+       si_read_unlock(sb);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void sysaufs_br_init(struct au_branch *br)
+{
+       br->br_attr.name = br->br_name;
+       br->br_attr.mode = S_IRUGO;
+       br->br_attr.owner = THIS_MODULE;
+}
+
+void sysaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex)
+{
+       struct au_branch *br;
+       struct kobject *kobj;
+       aufs_bindex_t bend;
+
+       dbgaufs_brs_del(sb, bindex);
+
+       if (!sysaufs_brs)
+               return;
+
+       kobj = &au_sbi(sb)->si_kobj;
+       bend = au_sbend(sb);
+       for (; bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               sysfs_remove_file(kobj, &br->br_attr);
+       }
+}
+
+void sysaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex)
+{
+       int err;
+       aufs_bindex_t bend;
+       struct kobject *kobj;
+       struct au_branch *br;
+
+       dbgaufs_brs_add(sb, bindex);
+
+       if (!sysaufs_brs)
+               return;
+
+       kobj = &au_sbi(sb)->si_kobj;
+       bend = au_sbend(sb);
+       for (; bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               snprintf(br->br_name, sizeof(br->br_name), SysaufsBr_PREFIX
+                        "%d", bindex);
+               err = sysfs_create_file(kobj, &br->br_attr);
+               if (unlikely(err))
+                       AuWarn("failed %s under sysfs(%d)\n", br->br_name, err);
+       }
+}
diff --git a/fs/aufs/sysrq.c b/fs/aufs/sysrq.c
new file mode 100644
index 0000000..419ff2c
--- /dev/null
+++ b/fs/aufs/sysrq.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * magic sysrq hanlder
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+/* #include <linux/sysrq.h> */
+#include "aufs.h"
+
+/* ---------------------------------------------------------------------- */
+
+static void sysrq_sb(struct super_block *sb)
+{
+       char *plevel;
+       struct au_sbinfo *sbinfo;
+       struct file *file;
+
+       plevel = au_plevel;
+       au_plevel = KERN_WARNING;
+       au_debug(1);
+
+       sbinfo = au_sbi(sb);
+       pr_warning("si=%lx\n", sysaufs_si_id(sbinfo));
+       pr_warning(AUFS_NAME ": superblock\n");
+       au_dpri_sb(sb);
+       pr_warning(AUFS_NAME ": root dentry\n");
+       au_dpri_dentry(sb->s_root);
+       pr_warning(AUFS_NAME ": root inode\n");
+       au_dpri_inode(sb->s_root->d_inode);
+#if 0
+       struct inode *i;
+       pr_warning(AUFS_NAME ": isolated inode\n");
+       list_for_each_entry(i, &sb->s_inodes, i_sb_list)
+               if (list_empty(&i->i_dentry))
+                       au_dpri_inode(i);
+#endif
+       pr_warning(AUFS_NAME ": files\n");
+       list_for_each_entry(file, &sb->s_files, f_u.fu_list)
+               if (!special_file(file->f_dentry->d_inode->i_mode))
+                       au_dpri_file(file);
+
+       au_plevel = plevel;
+       au_debug(0);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* module parameter */
+static char *aufs_sysrq_key = "a";
+module_param_named(sysrq, aufs_sysrq_key, charp, S_IRUGO);
+MODULE_PARM_DESC(sysrq, "MagicSysRq key for " AUFS_NAME);
+
+static void au_sysrq(int key __maybe_unused,
+                    struct tty_struct *tty __maybe_unused)
+{
+       struct kobject *kobj;
+       struct au_sbinfo *sbinfo;
+
+       /* spin_lock(&sysaufs_ket->list_lock); */
+       list_for_each_entry(kobj, &sysaufs_ket->list, entry) {
+               sbinfo = container_of(kobj, struct au_sbinfo, si_kobj);
+               sysrq_sb(sbinfo->si_sb);
+       }
+       /* spin_unlock(&sysaufs_ket->list_lock); */
+}
+
+static struct sysrq_key_op au_sysrq_op = {
+       .handler        = au_sysrq,
+       .help_msg       = "Aufs",
+       .action_msg     = "Aufs",
+       .enable_mask    = SYSRQ_ENABLE_DUMP
+};
+
+/* ---------------------------------------------------------------------- */
+
+int __init au_sysrq_init(void)
+{
+       int err;
+       char key;
+
+       err = -1;
+       key = *aufs_sysrq_key;
+       if ('a' <= key && key <= 'z')
+               err = register_sysrq_key(key, &au_sysrq_op);
+       if (unlikely(err))
+               AuErr("err %d, sysrq=%c\n", err, key);
+       return err;
+}
+
+void au_sysrq_fin(void)
+{
+       int err;
+       err = unregister_sysrq_key(*aufs_sysrq_key, &au_sysrq_op);
+       if (unlikely(err))
+               AuErr("err %d (ignored)\n", err);
+}
diff --git a/fs/aufs/vdir.c b/fs/aufs/vdir.c
new file mode 100644
index 0000000..9c7b64a
--- /dev/null
+++ b/fs/aufs/vdir.c
@@ -0,0 +1,796 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * virtual or vertical directory
+ */
+
+#include "aufs.h"
+
+static unsigned int calc_size(int namelen)
+{
+       int sz;
+       const int mask = sizeof(ino_t) - 1;
+
+       BUILD_BUG_ON(sizeof(ino_t) != sizeof(long));
+
+       sz = sizeof(struct au_vdir_de) + namelen;
+       if (sz & mask) {
+               sz += sizeof(ino_t);
+               sz &= ~mask;
+       }
+
+       AuDebugOn(sz % sizeof(ino_t));
+       return sz;
+}
+
+static int set_deblk_end(union au_vdir_deblk_p *p,
+                        union au_vdir_deblk_p *deblk_end)
+{
+       if (calc_size(0) <= deblk_end->deblk - p->deblk) {
+               p->de->de_str.len = 0;
+               /* smp_mb(); */
+               return 0;
+       }
+       return -1; /* error */
+}
+
+/* returns true or false */
+static int is_deblk_end(union au_vdir_deblk_p *p,
+                       union au_vdir_deblk_p *deblk_end)
+{
+       if (calc_size(0) <= deblk_end->deblk - p->deblk)
+               return !p->de->de_str.len;
+       return 1;
+}
+
+static unsigned char *last_deblk(struct au_vdir *vdir)
+{
+       return vdir->vd_deblk[vdir->vd_nblk - 1];
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * the allocated memory has to be freed by
+ * au_nhash_wh_free() or void au_nhash_de_free().
+ */
+struct au_nhash *au_nhash_alloc(struct super_block *sb, aufs_bindex_t bend,
+                               gfp_t gfp)
+{
+       struct au_nhash *nhash;
+       struct hlist_head *head;
+       unsigned int u, n;
+       aufs_bindex_t bindex;
+
+       nhash = kmalloc(sizeof(*nhash) * (bend + 1), gfp);
+       if (unlikely(!nhash))
+               goto out;
+
+       n = au_sbi(sb)->si_rdhash;
+       for (bindex = 0; bindex <= bend; bindex++) {
+               head = kmalloc(sizeof(*nhash->nh_head) * n, gfp);
+               if (unlikely(!head))
+                       goto out_free;
+               nhash[bindex].nh_num = n;
+               nhash[bindex].nh_head = head;
+               for (u = 0; u < n; u++)
+                       INIT_HLIST_HEAD(head++);
+       }
+       return nhash; /* success */
+
+ out_free:
+       for (bindex--; bindex >= 0; bindex--)
+               kfree(nhash[bindex].nh_head);
+       kfree(nhash);
+ out:
+       return ERR_PTR(-ENOMEM);
+}
+
+static void au_nhash_wh_do_free(struct au_nhash *whlist)
+{
+       unsigned int u, n;
+       struct hlist_head *head;
+       struct au_vdir_wh *tpos;
+       struct hlist_node *pos, *node;
+
+       n = whlist->nh_num;
+       head = whlist->nh_head;
+       for (u = 0; u < n; u++) {
+               hlist_for_each_entry_safe(tpos, pos, node, head, wh_hash) {
+                       /* hlist_del(pos); */
+                       kfree(tpos);
+               }
+               head++;
+       }
+}
+
+void au_nhash_wh_free(struct au_nhash *whlist, aufs_bindex_t bend)
+{
+       aufs_bindex_t bindex;
+
+       for (bindex = 0; bindex <= bend; bindex++) {
+               au_nhash_wh_do_free(whlist + bindex);
+               kfree(whlist[bindex].nh_head);
+       }
+
+       kfree(whlist);
+}
+
+static void au_nhash_de_do_free(struct au_nhash *delist)
+{
+       unsigned int u, n;
+       struct hlist_head *head;
+       struct au_vdir_dehstr *tpos;
+       struct hlist_node *pos, *node;
+
+       n = delist->nh_num;
+       head = delist->nh_head;
+       for (u = 0; u < n; u++) {
+               hlist_for_each_entry_safe(tpos, pos, node, head, hash) {
+                       /* hlist_del(pos); */
+                       au_cache_free_dehstr(tpos);
+               }
+               head++;
+       }
+}
+
+static void au_nhash_de_free(struct au_nhash *delist, aufs_bindex_t bend)
+{
+       aufs_bindex_t bindex;
+
+       for (bindex = 0; bindex <= bend; bindex++) {
+               au_nhash_de_do_free(delist + bindex);
+               kfree(delist[bindex].nh_head);
+       }
+
+       kfree(delist);
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_nhash_test_longer_wh(struct au_nhash *whlist, aufs_bindex_t btgt,
+                           int limit)
+{
+       int num;
+       unsigned int u, n;
+       struct hlist_head *head;
+       struct au_vdir_wh *tpos;
+       struct hlist_node *pos;
+
+       num = 0;
+       n = whlist->nh_num;
+       head = whlist->nh_head;
+       for (u = 0; u < n; u++) {
+               hlist_for_each_entry(tpos, pos, head, wh_hash)
+                       if (tpos->wh_bindex == btgt && ++num > limit)
+                               return 1;
+               head++;
+       }
+       return 0;
+}
+
+static struct hlist_head *au_name_hash(struct au_nhash *nhash,
+                                      const unsigned char *name,
+                                      unsigned int len)
+{
+       return nhash->nh_head + full_name_hash(name, len) % nhash->nh_num;
+}
+
+/* returns found or not */
+int au_nhash_test_known_wh(struct au_nhash *whlist, char *name, int namelen)
+{
+       struct hlist_head *head;
+       struct au_vdir_wh *tpos;
+       struct hlist_node *pos;
+       struct au_vdir_destr *str;
+
+       head = au_name_hash(whlist, name, namelen);
+       hlist_for_each_entry(tpos, pos, head, wh_hash) {
+               str = &tpos->wh_str;
+               AuDbg("%.*s\n", str->len, str->name);
+               if (str->len == namelen && !memcmp(str->name, name, namelen))
+                       return 1;
+       }
+       return 0;
+}
+
+int au_nhash_append_wh(struct au_nhash *whlist, char *name, int namelen,
+                      aufs_bindex_t bindex)
+{
+       int err;
+       struct au_vdir_destr *str;
+       struct au_vdir_wh *wh;
+
+       err = -ENOMEM;
+       wh = kmalloc(sizeof(*wh) + namelen, GFP_NOFS);
+       if (unlikely(!wh))
+               goto out;
+
+       err = 0;
+       wh->wh_bindex = bindex;
+       str = &wh->wh_str;
+       str->len = namelen;
+       memcpy(str->name, name, namelen);
+       hlist_add_head(&wh->wh_hash, au_name_hash(whlist, name, namelen));
+       /* smp_mb(); */
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_vdir_free(struct au_vdir *vdir)
+{
+       unsigned char **deblk;
+
+       deblk = vdir->vd_deblk;
+       while (vdir->vd_nblk--)
+               kfree(*deblk++);
+       kfree(vdir->vd_deblk);
+       au_cache_free_vdir(vdir);
+}
+
+static int append_deblk(struct au_vdir *vdir)
+{
+       int err;
+       unsigned long sz, ul;
+       const unsigned int deblk_sz = vdir->vd_deblk_sz;
+       union au_vdir_deblk_p p, deblk_end;
+       unsigned char **o;
+
+       err = -ENOMEM;
+       sz = sizeof(*o) * vdir->vd_nblk;
+       o = au_kzrealloc(vdir->vd_deblk, sz, sz + sizeof(*o), GFP_NOFS);
+       if (unlikely(!o))
+               goto out;
+
+       vdir->vd_deblk = o;
+       p.deblk = kmalloc(deblk_sz, GFP_NOFS);
+       if (p.deblk) {
+               ul = vdir->vd_nblk++;
+               vdir->vd_deblk[ul] = p.deblk;
+               vdir->vd_last.ul = ul;
+               vdir->vd_last.p.deblk = p.deblk;
+               deblk_end.deblk = p.deblk + deblk_sz;
+               err = set_deblk_end(&p, &deblk_end);
+       }
+
+ out:
+       return err;
+}
+
+static struct au_vdir *alloc_vdir(struct super_block *sb)
+{
+       struct au_vdir *vdir;
+       int err;
+
+       err = -ENOMEM;
+       vdir = au_cache_alloc_vdir();
+       if (unlikely(!vdir))
+               goto out;
+
+       vdir->vd_deblk = kzalloc(sizeof(*vdir->vd_deblk), GFP_NOFS);
+       if (unlikely(!vdir->vd_deblk))
+               goto out_free;
+
+       vdir->vd_deblk_sz = au_sbi(sb)->si_rdblk;
+       vdir->vd_nblk = 0;
+       vdir->vd_version = 0;
+       vdir->vd_jiffy = 0;
+       err = append_deblk(vdir);
+       if (!err)
+               return vdir; /* success */
+
+       kfree(vdir->vd_deblk);
+
+ out_free:
+       au_cache_free_vdir(vdir);
+ out:
+       vdir = ERR_PTR(err);
+       return vdir;
+}
+
+static int reinit_vdir(struct au_vdir *vdir)
+{
+       int err;
+       union au_vdir_deblk_p p, deblk_end;
+
+       while (vdir->vd_nblk > 1) {
+               kfree(vdir->vd_deblk[vdir->vd_nblk - 1]);
+               /* vdir->vd_deblk[vdir->vd_nblk - 1] = NULL; */
+               vdir->vd_nblk--;
+       }
+       p.deblk = vdir->vd_deblk[0];
+       deblk_end.deblk = p.deblk + vdir->vd_deblk_sz;
+       err = set_deblk_end(&p, &deblk_end);
+       /* keep vd_dblk_sz */
+       vdir->vd_last.ul = 0;
+       vdir->vd_last.p.deblk = vdir->vd_deblk[0];
+       vdir->vd_version = 0;
+       vdir->vd_jiffy = 0;
+       /* smp_mb(); */
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* returns found(true) or not */
+static int test_known(struct au_nhash *delist, char *name, int namelen)
+{
+       struct hlist_head *head;
+       struct au_vdir_dehstr *tpos;
+       struct hlist_node *pos;
+       struct au_vdir_destr *str;
+
+       head = au_name_hash(delist, name, namelen);
+       hlist_for_each_entry(tpos, pos, head, hash) {
+               str = tpos->str;
+               AuDbg("%.*s\n", str->len, str->name);
+               if (str->len == namelen && !memcmp(str->name, name, namelen))
+                       return 1;
+       }
+       return 0;
+
+}
+
+static int append_de(struct au_vdir *vdir, char *name, int namelen, ino_t ino,
+                    unsigned int d_type, struct au_nhash *delist)
+{
+       int err;
+       unsigned int sz;
+       const unsigned int deblk_sz = vdir->vd_deblk_sz;
+       union au_vdir_deblk_p p, *room, deblk_end;
+       struct au_vdir_dehstr *dehstr;
+
+       p.deblk = last_deblk(vdir);
+       deblk_end.deblk = p.deblk + deblk_sz;
+       room = &vdir->vd_last.p;
+       AuDebugOn(room->deblk < p.deblk || deblk_end.deblk <= room->deblk
+                 || !is_deblk_end(room, &deblk_end));
+
+       sz = calc_size(namelen);
+       if (unlikely(sz > deblk_end.deblk - room->deblk)) {
+               err = append_deblk(vdir);
+               if (unlikely(err))
+                       goto out;
+
+               p.deblk = last_deblk(vdir);
+               deblk_end.deblk = p.deblk + deblk_sz;
+               /* smp_mb(); */
+               AuDebugOn(room->deblk != p.deblk);
+       }
+
+       err = -ENOMEM;
+       dehstr = au_cache_alloc_dehstr();
+       if (unlikely(!dehstr))
+               goto out;
+
+       dehstr->str = &room->de->de_str;
+       hlist_add_head(&dehstr->hash, au_name_hash(delist, name, namelen));
+       room->de->de_ino = ino;
+       room->de->de_type = d_type;
+       room->de->de_str.len = namelen;
+       memcpy(room->de->de_str.name, name, namelen);
+
+       err = 0;
+       room->deblk += sz;
+       if (unlikely(set_deblk_end(room, &deblk_end)))
+               err = append_deblk(vdir);
+       /* smp_mb(); */
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_ino(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                 unsigned int d_type, ino_t *ino)
+{
+       int err;
+       struct mutex *mtx;
+       const int isdir = (d_type == DT_DIR);
+
+       /* prevent hardlinks from race condition */
+       mtx = NULL;
+       if (!isdir) {
+               mtx = &au_sbr(sb, bindex)->br_xino.xi_nondir_mtx;
+               mutex_lock(mtx);
+       }
+       err = au_xino_read(sb, bindex, h_ino, ino);
+       if (unlikely(err))
+               goto out;
+
+       if (!*ino) {
+               err = -EIO;
+               *ino = au_xino_new_ino(sb);
+               if (unlikely(!*ino))
+                       goto out;
+               err = au_xino_write(sb, bindex, h_ino, *ino);
+               if (unlikely(err))
+                       goto out;
+       }
+
+ out:
+       if (!isdir)
+               mutex_unlock(mtx);
+       return err;
+}
+
+#define AuFillVdir_CALLED      1
+#define AuFillVdir_WHABLE      (1 << 1)
+#define au_ftest_fillvdir(flags, name) ((flags) & AuFillVdir_##name)
+#define au_fset_fillvdir(flags, name)  { (flags) |= AuFillVdir_##name; }
+#define au_fclr_fillvdir(flags, name)  { (flags) &= ~AuFillVdir_##name; }
+
+struct fillvdir_arg {
+       struct file             *file;
+       struct au_vdir          *vdir;
+       struct au_nhash         *delist;
+       struct au_nhash         *whlist;
+       aufs_bindex_t           bindex;
+       unsigned int            flags;
+       int                     err;
+};
+
+static int fillvdir(void *__arg, const char *__name, int namelen,
+                   loff_t offset __maybe_unused, u64 h_ino,
+                   unsigned int d_type)
+{
+       struct fillvdir_arg *arg = __arg;
+       char *name = (void *)__name;
+       struct super_block *sb;
+       struct au_nhash *delist, *whlist;
+       ino_t ino;
+       aufs_bindex_t bindex, bend;
+
+       bend = arg->bindex;
+       arg->err = 0;
+       au_fset_fillvdir(arg->flags, CALLED);
+       /* smp_mb(); */
+       if (namelen <= AUFS_WH_PFX_LEN
+           || memcmp(name, AUFS_WH_PFX, AUFS_WH_PFX_LEN)) {
+               delist = arg->delist;
+               whlist = arg->whlist;
+               for (bindex = 0; bindex < bend; bindex++)
+                       if (test_known(delist++, name, namelen)
+                           || au_nhash_test_known_wh(whlist + bindex, name,
+                                                     namelen))
+                               goto out; /* already exists or whiteouted */
+
+               sb = arg->file->f_dentry->d_sb;
+               arg->err = au_ino(sb, bend, h_ino, d_type, &ino);
+               if (!arg->err)
+                       arg->err = append_de(arg->vdir, name, namelen, ino,
+                                            d_type, arg->delist + bend);
+       } else if (au_ftest_fillvdir(arg->flags, WHABLE)) {
+               name += AUFS_WH_PFX_LEN;
+               namelen -= AUFS_WH_PFX_LEN;
+               whlist = arg->whlist;
+               for (bindex = 0; bindex < bend; bindex++)
+                       if (au_nhash_test_known_wh(whlist++, name, namelen))
+                               goto out; /* already whiteouted */
+
+               if (!arg->err)
+                       arg->err = au_nhash_append_wh
+                               (arg->whlist + bend, name, namelen, bend);
+       }
+
+ out:
+       if (!arg->err)
+               arg->vdir->vd_jiffy = jiffies;
+       /* smp_mb(); */
+       AuTraceErr(arg->err);
+       return arg->err;
+}
+
+static int au_do_read_vdir(struct fillvdir_arg *arg)
+{
+       int err;
+       loff_t offset;
+       aufs_bindex_t bend, bindex;
+       struct file *hf, *file;
+       struct super_block *sb;
+
+       err = -ENOMEM;
+       file = arg->file;
+       sb = file->f_dentry->d_sb;
+       bend = au_fbend(file);
+       arg->delist = au_nhash_alloc(sb, bend, GFP_NOFS);
+       if (unlikely(!arg->delist))
+               goto out;
+       arg->whlist = au_nhash_alloc(sb, bend, GFP_NOFS);
+       if (unlikely(!arg->whlist))
+               goto out_delist;
+
+       err = 0;
+       arg->flags = 0;
+       for (bindex = au_fbstart(file); !err && bindex <= bend; bindex++) {
+               hf = au_h_fptr(file, bindex);
+               if (!hf)
+                       continue;
+
+               offset = vfsub_llseek(hf, 0, SEEK_SET);
+               err = offset;
+               if (unlikely(offset))
+                       break;
+
+               arg->bindex = bindex;
+               au_fclr_fillvdir(arg->flags, WHABLE);
+               if (bindex != bend
+                   && au_br_whable(au_sbr_perm(sb, bindex)))
+                       au_fset_fillvdir(arg->flags, WHABLE);
+               do {
+                       arg->err = 0;
+                       au_fclr_fillvdir(arg->flags, CALLED);
+                       /* smp_mb(); */
+                       err = vfsub_readdir(hf, fillvdir, arg);
+                       if (err >= 0)
+                               err = arg->err;
+               } while (!err && au_ftest_fillvdir(arg->flags, CALLED));
+       }
+       au_nhash_wh_free(arg->whlist, bend);
+
+ out_delist:
+       au_nhash_de_free(arg->delist, bend);
+ out:
+       return err;
+}
+
+static int read_vdir(struct file *file, int may_read)
+{
+       int err;
+       unsigned long expire;
+       unsigned char do_read;
+       struct fillvdir_arg arg;
+       struct inode *inode;
+       struct au_vdir *vdir, *allocated;
+
+       err = 0;
+       inode = file->f_dentry->d_inode;
+       IMustLock(inode);
+       allocated = NULL;
+       do_read = 0;
+       expire = au_sbi(inode->i_sb)->si_rdcache;
+       vdir = au_ivdir(inode);
+       if (!vdir) {
+               do_read = 1;
+               vdir = alloc_vdir(inode->i_sb);
+               err = PTR_ERR(vdir);
+               if (IS_ERR(vdir))
+                       goto out;
+               err = 0;
+               allocated = vdir;
+       } else if (may_read
+                  && (inode->i_version != vdir->vd_version
+                      || time_after(jiffies, vdir->vd_jiffy + expire))) {
+               do_read = 1;
+               err = reinit_vdir(vdir);
+               if (unlikely(err))
+                       goto out;
+       }
+
+       if (!do_read)
+               return 0; /* success */
+
+       arg.file = file;
+       arg.vdir = vdir;
+       err = au_do_read_vdir(&arg);
+       if (!err) {
+               /* file->f_pos = 0; */
+               vdir->vd_version = inode->i_version;
+               vdir->vd_last.ul = 0;
+               vdir->vd_last.p.deblk = vdir->vd_deblk[0];
+               if (allocated)
+                       au_set_ivdir(inode, allocated);
+       } else if (allocated)
+               au_vdir_free(allocated);
+
+ out:
+       return err;
+}
+
+static int copy_vdir(struct au_vdir *tgt, struct au_vdir *src)
+{
+       int err, rerr;
+       unsigned long ul, n;
+       const unsigned int deblk_sz = src->vd_deblk_sz;
+
+       AuDebugOn(tgt->vd_nblk != 1);
+
+       err = -ENOMEM;
+       if (tgt->vd_nblk < src->vd_nblk) {
+               unsigned char **p;
+
+               p = au_kzrealloc(tgt->vd_deblk, sizeof(*p) * tgt->vd_nblk,
+                                sizeof(*p) * src->vd_nblk, GFP_NOFS);
+               if (unlikely(!p))
+                       goto out;
+               tgt->vd_deblk = p;
+       }
+
+       tgt->vd_nblk = src->vd_nblk;
+       tgt->vd_deblk_sz = deblk_sz;
+       memcpy(tgt->vd_deblk[0], src->vd_deblk[0], deblk_sz);
+       /* tgt->vd_last.i = 0; */
+       /* tgt->vd_last.p.deblk = tgt->vd_deblk[0]; */
+       tgt->vd_version = src->vd_version;
+       tgt->vd_jiffy = src->vd_jiffy;
+
+       n = src->vd_nblk;
+       for (ul = 1; ul < n; ul++) {
+               tgt->vd_deblk[ul] = kmalloc(deblk_sz, GFP_NOFS);
+               if (tgt->vd_deblk[ul])
+                       memcpy(tgt->vd_deblk[ul], src->vd_deblk[ul], deblk_sz);
+               else
+                       goto out;
+       }
+       /* smp_mb(); */
+       return 0; /* success */
+
+ out:
+       rerr = reinit_vdir(tgt);
+       BUG_ON(rerr);
+       return err;
+}
+
+int au_vdir_init(struct file *file)
+{
+       int err;
+       struct inode *inode;
+       struct au_vdir *vdir_cache, *allocated;
+
+       err = read_vdir(file, !file->f_pos);
+       if (unlikely(err))
+               goto out;
+
+       allocated = NULL;
+       vdir_cache = au_fvdir_cache(file);
+       if (!vdir_cache) {
+               vdir_cache = alloc_vdir(file->f_dentry->d_sb);
+               err = PTR_ERR(vdir_cache);
+               if (IS_ERR(vdir_cache))
+                       goto out;
+               allocated = vdir_cache;
+       } else if (!file->f_pos && vdir_cache->vd_version != file->f_version) {
+               err = reinit_vdir(vdir_cache);
+               if (unlikely(err))
+                       goto out;
+       } else
+               return 0; /* success */
+
+       inode = file->f_dentry->d_inode;
+       err = copy_vdir(vdir_cache, au_ivdir(inode));
+       if (!err) {
+               file->f_version = inode->i_version;
+               if (allocated)
+                       au_set_fvdir_cache(file, allocated);
+       } else if (allocated)
+               au_vdir_free(allocated);
+
+ out:
+       return err;
+}
+
+static loff_t calc_offset(struct au_vdir *vdir)
+{
+       loff_t offset;
+       union au_vdir_deblk_p p;
+
+       p.deblk = vdir->vd_deblk[vdir->vd_last.ul];
+       offset = vdir->vd_last.p.deblk - p.deblk;
+       offset += vdir->vd_deblk_sz * vdir->vd_last.ul;
+       return offset;
+}
+
+/* returns true or false */
+static int seek_vdir(struct file *file)
+{
+       int valid;
+       unsigned int deblk_sz;
+       unsigned long ul, n;
+       loff_t offset;
+       union au_vdir_deblk_p p, deblk_end;
+       struct au_vdir *vdir_cache;
+
+       valid = 1;
+       vdir_cache = au_fvdir_cache(file);
+       offset = calc_offset(vdir_cache);
+       AuDbg("offset %lld\n", offset);
+       if (file->f_pos == offset)
+               goto out;
+
+       vdir_cache->vd_last.ul = 0;
+       vdir_cache->vd_last.p.deblk = vdir_cache->vd_deblk[0];
+       if (!file->f_pos)
+               goto out;
+
+       valid = 0;
+       deblk_sz = vdir_cache->vd_deblk_sz;
+       ul = div64_u64(file->f_pos, deblk_sz);
+       AuDbg("ul %lu\n", ul);
+       if (ul >= vdir_cache->vd_nblk)
+               goto out;
+
+       n = vdir_cache->vd_nblk;
+       for (; ul < n; ul++) {
+               p.deblk = vdir_cache->vd_deblk[ul];
+               deblk_end.deblk = p.deblk + deblk_sz;
+               offset = ul;
+               offset *= deblk_sz;
+               while (!is_deblk_end(&p, &deblk_end) && offset < file->f_pos) {
+                       unsigned int l;
+
+                       l = calc_size(p.de->de_str.len);
+                       offset += l;
+                       p.deblk += l;
+               }
+               if (!is_deblk_end(&p, &deblk_end)) {
+                       valid = 1;
+                       vdir_cache->vd_last.ul = ul;
+                       vdir_cache->vd_last.p = p;
+                       break;
+               }
+       }
+
+ out:
+       /* smp_mb(); */
+       AuTraceErr(!valid);
+       return valid;
+}
+
+int au_vdir_fill_de(struct file *file, void *dirent, filldir_t filldir)
+{
+       int err;
+       unsigned int l, deblk_sz;
+       union au_vdir_deblk_p deblk_end;
+       struct au_vdir *vdir_cache;
+       struct au_vdir_de *de;
+
+       vdir_cache = au_fvdir_cache(file);
+       if (!seek_vdir(file))
+               return 0;
+
+       deblk_sz = vdir_cache->vd_deblk_sz;
+       while (1) {
+               deblk_end.deblk = vdir_cache->vd_deblk[vdir_cache->vd_last.ul];
+               deblk_end.deblk += deblk_sz;
+               while (!is_deblk_end(&vdir_cache->vd_last.p, &deblk_end)) {
+                       de = vdir_cache->vd_last.p.de;
+                       AuDbg("%.*s, off%lld, i%lu, dt%d\n",
+                             de->de_str.len, de->de_str.name, file->f_pos,
+                             (unsigned long)de->de_ino, de->de_type);
+                       err = filldir(dirent, de->de_str.name, de->de_str.len,
+                                     file->f_pos, de->de_ino, de->de_type);
+                       if (unlikely(err)) {
+                               AuTraceErr(err);
+                               /* todo: ignore the error caused by udba? */
+                               /* return err; */
+                               return 0;
+                       }
+
+                       l = calc_size(de->de_str.len);
+                       vdir_cache->vd_last.p.deblk += l;
+                       file->f_pos += l;
+               }
+               if (vdir_cache->vd_last.ul < vdir_cache->vd_nblk - 1) {
+                       vdir_cache->vd_last.ul++;
+                       vdir_cache->vd_last.p.deblk
+                               = vdir_cache->vd_deblk[vdir_cache->vd_last.ul];
+                       file->f_pos = deblk_sz * vdir_cache->vd_last.ul;
+                       continue;
+               }
+               break;
+       }
+
+       /* smp_mb(); */
+       return 0;
+}
diff --git a/fs/aufs/vfsub.c b/fs/aufs/vfsub.c
new file mode 100644
index 0000000..f58d07d
--- /dev/null
+++ b/fs/aufs/vfsub.c
@@ -0,0 +1,724 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sub-routines for VFS
+ */
+
+#include <linux/uaccess.h>
+#include "aufs.h"
+
+int vfsub_update_h_iattr(struct path *h_path, int *did)
+{
+       int err;
+       struct kstat st;
+       struct super_block *h_sb;
+
+       /* for remote fs, leave work for its getattr or d_revalidate */
+       /* for bad i_attr fs, handle them in aufs_getattr() */
+       /* still some fs may acquire i_mutex. we need to skip them */
+       err = 0;
+       if (!did)
+               did = &err;
+       h_sb = h_path->dentry->d_sb;
+       *did = (!au_test_fs_remote(h_sb) && au_test_fs_refresh_iattr(h_sb));
+       if (*did)
+               err = vfs_getattr(h_path->mnt, h_path->dentry, &st);
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct file *vfsub_filp_open(const char *path, int oflags, int mode)
+{
+       struct file *file;
+
+       lockdep_off();
+       file = filp_open(path, oflags, mode);
+       lockdep_on();
+       if (IS_ERR(file))
+               goto out;
+       vfsub_update_h_iattr(&file->f_path, /*did*/NULL); /*ignore*/
+
+ out:
+       return file;
+}
+
+int vfsub_kern_path(const char *name, unsigned int flags, struct path *path)
+{
+       int err;
+
+       /* lockdep_off(); */
+       err = kern_path(name, flags, path);
+       /* lockdep_on(); */
+       if (!err && path->dentry->d_inode)
+               vfsub_update_h_iattr(path, /*did*/NULL); /*ignore*/
+       return err;
+}
+
+struct dentry *vfsub_lookup_one_len(const char *name, struct dentry *parent,
+                                   int len)
+{
+       struct path path = {
+               .mnt = NULL
+       };
+
+       IMustLock(parent->d_inode);
+
+       path.dentry = lookup_one_len(name, parent, len);
+       if (IS_ERR(path.dentry))
+               goto out;
+       if (path.dentry->d_inode)
+               vfsub_update_h_iattr(&path, /*did*/NULL); /*ignore*/
+
+ out:
+       return path.dentry;
+}
+
+struct dentry *vfsub_lookup_hash(struct nameidata *nd)
+{
+       struct path path = {
+               .mnt = nd->path.mnt
+       };
+
+       IMustLock(nd->path.dentry->d_inode);
+
+       path.dentry = lookup_hash(nd);
+       if (!IS_ERR(path.dentry) && path.dentry->d_inode)
+               vfsub_update_h_iattr(&path, /*did*/NULL); /*ignore*/
+
+       return path.dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct dentry *vfsub_lock_rename(struct dentry *d1, struct au_hinode *hdir1,
+                                struct dentry *d2, struct au_hinode *hdir2)
+{
+       struct dentry *d;
+
+       lockdep_off();
+       d = lock_rename(d1, d2);
+       lockdep_on();
+       au_hin_suspend(hdir1);
+       if (hdir1 != hdir2)
+               au_hin_suspend(hdir2);
+
+       return d;
+}
+
+void vfsub_unlock_rename(struct dentry *d1, struct au_hinode *hdir1,
+                        struct dentry *d2, struct au_hinode *hdir2)
+{
+       au_hin_resume(hdir1);
+       if (hdir1 != hdir2)
+               au_hin_resume(hdir2);
+       lockdep_off();
+       unlock_rename(d1, d2);
+       lockdep_on();
+}
+
+/* ---------------------------------------------------------------------- */
+
+int vfsub_create(struct inode *dir, struct path *path, int mode)
+{
+       int err;
+       struct dentry *d;
+
+       IMustLock(dir);
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       err = security_path_mknod(path, path->dentry, mode, 0);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       if (au_test_fs_null_nd(dir->i_sb))
+               err = vfs_create(dir, path->dentry, mode, NULL);
+       else {
+               struct nameidata h_nd;
+
+               memset(&h_nd, 0, sizeof(h_nd));
+               h_nd.flags = LOOKUP_CREATE;
+               h_nd.intent.open.flags = O_CREAT
+                       | vfsub_fmode_to_uint(FMODE_READ);
+               h_nd.intent.open.create_mode = mode;
+               h_nd.path.dentry = path->dentry->d_parent;
+               h_nd.path.mnt = path->mnt;
+               path_get(&h_nd.path);
+               err = vfs_create(dir, path->dentry, mode, &h_nd);
+               path_put(&h_nd.path);
+       }
+
+       if (!err) {
+               struct path tmp = *path;
+               int did;
+
+               vfsub_update_h_iattr(&tmp, &did);
+               if (did) {
+                       tmp.dentry = path->dentry->d_parent;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+               }
+               /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+int vfsub_symlink(struct inode *dir, struct path *path, const char *symname)
+{
+       int err;
+       struct dentry *d;
+
+       IMustLock(dir);
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       err = security_path_symlink(path, path->dentry, symname);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       err = vfs_symlink(dir, path->dentry, symname);
+       if (!err) {
+               struct path tmp = *path;
+               int did;
+
+               vfsub_update_h_iattr(&tmp, &did);
+               if (did) {
+                       tmp.dentry = path->dentry->d_parent;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+               }
+               /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+int vfsub_mknod(struct inode *dir, struct path *path, int mode, dev_t dev)
+{
+       int err;
+       struct dentry *d;
+
+       IMustLock(dir);
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       err = security_path_mknod(path, path->dentry, mode, dev);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       err = vfs_mknod(dir, path->dentry, mode, dev);
+       if (!err) {
+               struct path tmp = *path;
+               int did;
+
+               vfsub_update_h_iattr(&tmp, &did);
+               if (did) {
+                       tmp.dentry = path->dentry->d_parent;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+               }
+               /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+static int au_test_nlink(struct inode *inode)
+{
+       const unsigned int link_max = UINT_MAX >> 1; /* rough margin */
+
+       if (!au_test_fs_no_limit_nlink(inode->i_sb)
+           || inode->i_nlink < link_max)
+               return 0;
+       return -EMLINK;
+}
+
+int vfsub_link(struct dentry *src_dentry, struct inode *dir, struct path *path)
+{
+       int err;
+       struct dentry *d;
+
+       IMustLock(dir);
+
+       err = au_test_nlink(src_dentry->d_inode);
+       if (unlikely(err))
+               return err;
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       err = security_path_link(src_dentry, path, path->dentry);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       lockdep_off();
+       err = vfs_link(src_dentry, dir, path->dentry);
+       lockdep_on();
+       if (!err) {
+               struct path tmp = *path;
+               int did;
+
+               /* fuse has different memory inode for the same inumber */
+               vfsub_update_h_iattr(&tmp, &did);
+               if (did) {
+                       tmp.dentry = path->dentry->d_parent;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+                       tmp.dentry = src_dentry;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+               }
+               /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+int vfsub_rename(struct inode *src_dir, struct dentry *src_dentry,
+                struct inode *dir, struct path *path)
+{
+       int err;
+       struct path tmp = {
+               .mnt    = path->mnt
+       };
+       struct dentry *d;
+
+       IMustLock(dir);
+       IMustLock(src_dir);
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       tmp.dentry = src_dentry->d_parent;
+       err = security_path_rename(&tmp, src_dentry, path, path->dentry);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       lockdep_off();
+       err = vfs_rename(src_dir, src_dentry, dir, path->dentry);
+       lockdep_on();
+       if (!err) {
+               int did;
+
+               tmp.dentry = d->d_parent;
+               vfsub_update_h_iattr(&tmp, &did);
+               if (did) {
+                       tmp.dentry = src_dentry;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+                       tmp.dentry = src_dentry->d_parent;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+               }
+               /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+int vfsub_mkdir(struct inode *dir, struct path *path, int mode)
+{
+       int err;
+       struct dentry *d;
+
+       IMustLock(dir);
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       err = security_path_mkdir(path, path->dentry, mode);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       err = vfs_mkdir(dir, path->dentry, mode);
+       if (!err) {
+               struct path tmp = *path;
+               int did;
+
+               vfsub_update_h_iattr(&tmp, &did);
+               if (did) {
+                       tmp.dentry = path->dentry->d_parent;
+                       vfsub_update_h_iattr(&tmp, /*did*/NULL);
+               }
+               /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+int vfsub_rmdir(struct inode *dir, struct path *path)
+{
+       int err;
+       struct dentry *d;
+
+       IMustLock(dir);
+
+       d = path->dentry;
+       path->dentry = d->d_parent;
+       err = security_path_rmdir(path, path->dentry);
+       path->dentry = d;
+       if (unlikely(err))
+               goto out;
+
+       lockdep_off();
+       err = vfs_rmdir(dir, path->dentry);
+       lockdep_on();
+       if (!err) {
+               struct path tmp = {
+                       .dentry = path->dentry->d_parent,
+                       .mnt    = path->mnt
+               };
+
+               vfsub_update_h_iattr(&tmp, /*did*/NULL); /*ignore*/
+       }
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+ssize_t vfsub_read_u(struct file *file, char __user *ubuf, size_t count,
+                    loff_t *ppos)
+{
+       ssize_t err;
+
+       err = vfs_read(file, ubuf, count, ppos);
+       if (err >= 0)
+               vfsub_update_h_iattr(&file->f_path, /*did*/NULL); /*ignore*/
+       return err;
+}
+
+/* todo: kernel_read()? */
+ssize_t vfsub_read_k(struct file *file, void *kbuf, size_t count,
+                    loff_t *ppos)
+{
+       ssize_t err;
+       mm_segment_t oldfs;
+
+       oldfs = get_fs();
+       set_fs(KERNEL_DS);
+       err = vfsub_read_u(file, (char __user *)kbuf, count, ppos);
+       set_fs(oldfs);
+       return err;
+}
+
+ssize_t vfsub_write_u(struct file *file, const char __user *ubuf, size_t count,
+                     loff_t *ppos)
+{
+       ssize_t err;
+
+       lockdep_off();
+       err = vfs_write(file, ubuf, count, ppos);
+       lockdep_on();
+       if (err >= 0)
+               vfsub_update_h_iattr(&file->f_path, /*did*/NULL); /*ignore*/
+       return err;
+}
+
+ssize_t vfsub_write_k(struct file *file, void *kbuf, size_t count, loff_t *ppos)
+{
+       ssize_t err;
+       mm_segment_t oldfs;
+
+       oldfs = get_fs();
+       set_fs(KERNEL_DS);
+       err = vfsub_write_u(file, (const char __user *)kbuf, count, ppos);
+       set_fs(oldfs);
+       return err;
+}
+
+int vfsub_readdir(struct file *file, filldir_t filldir, void *arg)
+{
+       int err;
+
+       lockdep_off();
+       err = vfs_readdir(file, filldir, arg);
+       lockdep_on();
+       if (err >= 0)
+               vfsub_update_h_iattr(&file->f_path, /*did*/NULL); /*ignore*/
+       return err;
+}
+
+long vfsub_splice_to(struct file *in, loff_t *ppos,
+                    struct pipe_inode_info *pipe, size_t len,
+                    unsigned int flags)
+{
+       long err;
+
+       lockdep_off();
+       err = do_splice_to(in, ppos, pipe, len, flags);
+       lockdep_on();
+       if (err >= 0)
+               vfsub_update_h_iattr(&in->f_path, /*did*/NULL); /*ignore*/
+       return err;
+}
+
+long vfsub_splice_from(struct pipe_inode_info *pipe, struct file *out,
+                      loff_t *ppos, size_t len, unsigned int flags)
+{
+       long err;
+
+       lockdep_off();
+       err = do_splice_from(pipe, out, ppos, len, flags);
+       lockdep_on();
+       if (err >= 0)
+               vfsub_update_h_iattr(&out->f_path, /*did*/NULL); /*ignore*/
+       return err;
+}
+
+/* cf. open.c:do_sys_truncate() and do_sys_ftruncate() */
+int vfsub_trunc(struct path *h_path, loff_t length, unsigned int attr,
+               struct file *h_file)
+{
+       int err;
+       struct inode *h_inode;
+
+       h_inode = h_path->dentry->d_inode;
+       if (!h_file) {
+               err = mnt_want_write(h_path->mnt);
+               if (err)
+                       goto out;
+               err = inode_permission(h_inode, MAY_WRITE);
+               if (err)
+                       goto out_mnt;
+               err = get_write_access(h_inode);
+               if (err)
+                       goto out_mnt;
+               err = break_lease(h_inode, vfsub_fmode_to_uint(FMODE_WRITE));
+               if (err)
+                       goto out_inode;
+       }
+
+       err = locks_verify_truncate(h_inode, h_file, length);
+       if (!err)
+               err = security_path_truncate(h_path, length, attr);
+       if (!err) {
+               lockdep_off();
+               err = do_truncate(h_path->dentry, length, attr, h_file);
+               lockdep_on();
+       }
+
+ out_inode:
+       if (!h_file)
+               put_write_access(h_inode);
+ out_mnt:
+       if (!h_file)
+               mnt_drop_write(h_path->mnt);
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct au_vfsub_mkdir_args {
+       int *errp;
+       struct inode *dir;
+       struct path *path;
+       int mode;
+};
+
+static void au_call_vfsub_mkdir(void *args)
+{
+       struct au_vfsub_mkdir_args *a = args;
+       *a->errp = vfsub_mkdir(a->dir, a->path, a->mode);
+}
+
+int vfsub_sio_mkdir(struct inode *dir, struct path *path, int mode)
+{
+       int err, do_sio, wkq_err;
+
+       do_sio = au_test_h_perm_sio(dir, MAY_EXEC | MAY_WRITE);
+       if (!do_sio)
+               err = vfsub_mkdir(dir, path, mode);
+       else {
+               struct au_vfsub_mkdir_args args = {
+                       .errp   = &err,
+                       .dir    = dir,
+                       .path   = path,
+                       .mode   = mode
+               };
+               wkq_err = au_wkq_wait(au_call_vfsub_mkdir, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+
+       return err;
+}
+
+struct au_vfsub_rmdir_args {
+       int *errp;
+       struct inode *dir;
+       struct path *path;
+};
+
+static void au_call_vfsub_rmdir(void *args)
+{
+       struct au_vfsub_rmdir_args *a = args;
+       *a->errp = vfsub_rmdir(a->dir, a->path);
+}
+
+int vfsub_sio_rmdir(struct inode *dir, struct path *path)
+{
+       int err, do_sio, wkq_err;
+
+       do_sio = au_test_h_perm_sio(dir, MAY_EXEC | MAY_WRITE);
+       if (!do_sio)
+               err = vfsub_rmdir(dir, path);
+       else {
+               struct au_vfsub_rmdir_args args = {
+                       .errp   = &err,
+                       .dir    = dir,
+                       .path   = path
+               };
+               wkq_err = au_wkq_wait(au_call_vfsub_rmdir, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct notify_change_args {
+       int *errp;
+       struct path *path;
+       struct iattr *ia;
+};
+
+static void call_notify_change(void *args)
+{
+       struct notify_change_args *a = args;
+       struct inode *h_inode;
+
+       h_inode = a->path->dentry->d_inode;
+       IMustLock(h_inode);
+
+       *a->errp = -EPERM;
+       if (!IS_IMMUTABLE(h_inode) && !IS_APPEND(h_inode)) {
+               lockdep_off();
+               *a->errp = notify_change(a->path->dentry, a->ia);
+               lockdep_on();
+               if (!*a->errp)
+                       vfsub_update_h_iattr(a->path, /*did*/NULL); /*ignore*/
+       }
+       AuTraceErr(*a->errp);
+}
+
+int vfsub_notify_change(struct path *path, struct iattr *ia)
+{
+       int err;
+       struct notify_change_args args = {
+               .errp   = &err,
+               .path   = path,
+               .ia     = ia
+       };
+
+       call_notify_change(&args);
+
+       return err;
+}
+
+int vfsub_sio_notify_change(struct path *path, struct iattr *ia)
+{
+       int err, wkq_err;
+       struct notify_change_args args = {
+               .errp   = &err,
+               .path   = path,
+               .ia     = ia
+       };
+
+       wkq_err = au_wkq_wait(call_notify_change, &args);
+       if (unlikely(wkq_err))
+               err = wkq_err;
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct unlink_args {
+       int *errp;
+       struct inode *dir;
+       struct path *path;
+};
+
+static void call_unlink(void *args)
+{
+       struct unlink_args *a = args;
+       struct dentry *d = a->path->dentry;
+       struct inode *h_inode;
+       const int stop_sillyrename = (au_test_nfs(d->d_sb)
+                                     && atomic_read(&d->d_count) == 1);
+
+       IMustLock(a->dir);
+
+       a->path->dentry = d->d_parent;
+       *a->errp = security_path_unlink(a->path, d);
+       a->path->dentry = d;
+       if (unlikely(*a->errp))
+               return;
+
+       if (!stop_sillyrename)
+               dget(d);
+       h_inode = d->d_inode;
+       if (h_inode)
+               atomic_inc(&h_inode->i_count);
+
+       lockdep_off();
+       *a->errp = vfs_unlink(a->dir, d);
+       lockdep_on();
+       if (!*a->errp) {
+               struct path tmp = {
+                       .dentry = d->d_parent,
+                       .mnt    = a->path->mnt
+               };
+               vfsub_update_h_iattr(&tmp, /*did*/NULL); /*ignore*/
+       }
+
+       if (!stop_sillyrename)
+               dput(d);
+       if (h_inode)
+               iput(h_inode);
+
+       AuTraceErr(*a->errp);
+}
+
+/*
+ * @dir: must be locked.
+ * @dentry: target dentry.
+ */
+int vfsub_unlink(struct inode *dir, struct path *path, int force)
+{
+       int err;
+       struct unlink_args args = {
+               .errp   = &err,
+               .dir    = dir,
+               .path   = path
+       };
+
+       if (!force)
+               call_unlink(&args);
+       else {
+               int wkq_err;
+
+               wkq_err = au_wkq_wait(call_unlink, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+
+       return err;
+}
diff --git a/fs/aufs/vfsub.h b/fs/aufs/vfsub.h
new file mode 100644
index 0000000..d0172c7
--- /dev/null
+++ b/fs/aufs/vfsub.h
@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * sub-routines for VFS
+ */
+
+#ifndef __AUFS_VFSUB_H__
+#define __AUFS_VFSUB_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/fs_stack.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/splice.h>
+
+/* ---------------------------------------------------------------------- */
+
+/* lock subclass for lower inode */
+/* default MAX_LOCKDEP_SUBCLASSES(8) is not enough */
+/* reduce? gave up. */
+enum {
+       AuLsc_I_Begin = I_MUTEX_QUOTA, /* 4 */
+       AuLsc_I_PARENT,         /* lower inode, parent first */
+       AuLsc_I_PARENT2,        /* copyup dirs */
+       AuLsc_I_CHILD,
+       AuLsc_I_CHILD2,
+       AuLsc_I_End
+};
+
+/* to debug easier, do not make them inlined functions */
+#define MtxMustLock(mtx)       AuDebugOn(!mutex_is_locked(mtx))
+#define IMustLock(i)           MtxMustLock(&(i)->i_mutex)
+
+/* ---------------------------------------------------------------------- */
+
+static inline void vfsub_copy_inode_size(struct inode *inode,
+                                        struct inode *h_inode)
+{
+       spin_lock(&inode->i_lock);
+       fsstack_copy_inode_size(inode, h_inode);
+       spin_unlock(&inode->i_lock);
+}
+
+int vfsub_update_h_iattr(struct path *h_path, int *did);
+struct file *vfsub_filp_open(const char *path, int oflags, int mode);
+int vfsub_kern_path(const char *name, unsigned int flags, struct path *path);
+struct dentry *vfsub_lookup_one_len(const char *name, struct dentry *parent,
+                                   int len);
+struct dentry *vfsub_lookup_hash(struct nameidata *nd);
+
+/* ---------------------------------------------------------------------- */
+
+struct au_hinode;
+struct dentry *vfsub_lock_rename(struct dentry *d1, struct au_hinode *hdir1,
+                                struct dentry *d2, struct au_hinode *hdir2);
+void vfsub_unlock_rename(struct dentry *d1, struct au_hinode *hdir1,
+                        struct dentry *d2, struct au_hinode *hdir2);
+
+int vfsub_create(struct inode *dir, struct path *path, int mode);
+int vfsub_symlink(struct inode *dir, struct path *path,
+                 const char *symname);
+int vfsub_mknod(struct inode *dir, struct path *path, int mode, dev_t dev);
+int vfsub_link(struct dentry *src_dentry, struct inode *dir,
+              struct path *path);
+int vfsub_rename(struct inode *src_hdir, struct dentry *src_dentry,
+                struct inode *hdir, struct path *path);
+int vfsub_mkdir(struct inode *dir, struct path *path, int mode);
+int vfsub_rmdir(struct inode *dir, struct path *path);
+
+/* ---------------------------------------------------------------------- */
+
+ssize_t vfsub_read_u(struct file *file, char __user *ubuf, size_t count,
+                    loff_t *ppos);
+ssize_t vfsub_read_k(struct file *file, void *kbuf, size_t count,
+                       loff_t *ppos);
+ssize_t vfsub_write_u(struct file *file, const char __user *ubuf, size_t count,
+                     loff_t *ppos);
+ssize_t vfsub_write_k(struct file *file, void *kbuf, size_t count,
+                     loff_t *ppos);
+int vfsub_readdir(struct file *file, filldir_t filldir, void *arg);
+
+static inline void vfsub_file_accessed(struct file *h_file)
+{
+       file_accessed(h_file);
+       vfsub_update_h_iattr(&h_file->f_path, /*did*/NULL); /*ignore*/
+}
+
+static inline void vfsub_touch_atime(struct vfsmount *h_mnt,
+                                    struct dentry *h_dentry)
+{
+       struct path h_path = {
+               .dentry = h_dentry,
+               .mnt    = h_mnt
+       };
+       touch_atime(h_mnt, h_dentry);
+       vfsub_update_h_iattr(&h_path, /*did*/NULL); /*ignore*/
+}
+
+long vfsub_splice_to(struct file *in, loff_t *ppos,
+                    struct pipe_inode_info *pipe, size_t len,
+                    unsigned int flags);
+long vfsub_splice_from(struct pipe_inode_info *pipe, struct file *out,
+                      loff_t *ppos, size_t len, unsigned int flags);
+int vfsub_trunc(struct path *h_path, loff_t length, unsigned int attr,
+               struct file *h_file);
+
+/* ---------------------------------------------------------------------- */
+
+static inline loff_t vfsub_llseek(struct file *file, loff_t offset, int origin)
+{
+       loff_t err;
+
+       lockdep_off();
+       err = vfs_llseek(file, offset, origin);
+       lockdep_on();
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* dirty workaround for strict type of fmode_t */
+union vfsub_fmu {
+       fmode_t fm;
+       unsigned int ui;
+};
+
+static inline unsigned int vfsub_fmode_to_uint(fmode_t fm)
+{
+       union vfsub_fmu u = {
+               .fm = fm
+       };
+
+       BUILD_BUG_ON(sizeof(u.fm) != sizeof(u.ui));
+
+       return u.ui;
+}
+
+static inline fmode_t vfsub_uint_to_fmode(unsigned int ui)
+{
+       union vfsub_fmu u = {
+               .ui = ui
+       };
+
+       return u.fm;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int vfsub_sio_mkdir(struct inode *dir, struct path *path, int mode);
+int vfsub_sio_rmdir(struct inode *dir, struct path *path);
+int vfsub_sio_notify_change(struct path *path, struct iattr *ia);
+int vfsub_notify_change(struct path *path, struct iattr *ia);
+int vfsub_unlink(struct inode *dir, struct path *path, int force);
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_VFSUB_H__ */
diff --git a/fs/aufs/wbr_policy.c b/fs/aufs/wbr_policy.c
new file mode 100644
index 0000000..436ebfc
--- /dev/null
+++ b/fs/aufs/wbr_policy.c
@@ -0,0 +1,628 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * policies for selecting one among multiple writable branches
+ */
+
+#include <linux/statfs.h>
+#include "aufs.h"
+
+/* subset of cpup_attr() */
+static noinline_for_stack
+int au_cpdown_attr(struct path *h_path, struct dentry *h_src)
+{
+       int err, sbits;
+       struct iattr ia;
+       struct inode *h_isrc;
+
+       h_isrc = h_src->d_inode;
+       ia.ia_valid = ATTR_FORCE | ATTR_MODE | ATTR_UID | ATTR_GID;
+       ia.ia_mode = h_isrc->i_mode;
+       ia.ia_uid = h_isrc->i_uid;
+       ia.ia_gid = h_isrc->i_gid;
+       sbits = !!(ia.ia_mode & (S_ISUID | S_ISGID));
+       au_cpup_attr_flags(h_path->dentry->d_inode, h_isrc);
+       err = vfsub_sio_notify_change(h_path, &ia);
+
+       /* is this nfs only? */
+       if (!err && sbits && au_test_nfs(h_path->dentry->d_sb)) {
+               ia.ia_valid = ATTR_FORCE | ATTR_MODE;
+               ia.ia_mode = h_isrc->i_mode;
+               err = vfsub_sio_notify_change(h_path, &ia);
+       }
+
+       return err;
+}
+
+#define AuCpdown_PARENT_OPQ    1
+#define AuCpdown_WHED          (1 << 1)
+#define AuCpdown_MADE_DIR      (1 << 2)
+#define AuCpdown_DIROPQ                (1 << 3)
+#define au_ftest_cpdown(flags, name)   ((flags) & AuCpdown_##name)
+#define au_fset_cpdown(flags, name)    { (flags) |= AuCpdown_##name; }
+#define au_fclr_cpdown(flags, name)    { (flags) &= ~AuCpdown_##name; }
+
+struct au_cpdown_dir_args {
+       struct dentry *parent;
+       unsigned int flags;
+};
+
+static int au_cpdown_dir_opq(struct dentry *dentry, aufs_bindex_t bdst,
+                            struct au_cpdown_dir_args *a)
+{
+       int err;
+       struct dentry *opq_dentry;
+
+       opq_dentry = au_diropq_create(dentry, bdst);
+       err = PTR_ERR(opq_dentry);
+       if (IS_ERR(opq_dentry))
+               goto out;
+       dput(opq_dentry);
+       au_fset_cpdown(a->flags, DIROPQ);
+
+ out:
+       return err;
+}
+
+static int au_cpdown_dir_wh(struct dentry *dentry, struct dentry *h_parent,
+                           struct inode *dir, aufs_bindex_t bdst)
+{
+       int err;
+       struct path h_path;
+       struct au_branch *br;
+
+       br = au_sbr(dentry->d_sb, bdst);
+       h_path.dentry = au_wh_lkup(h_parent, &dentry->d_name, br);
+       err = PTR_ERR(h_path.dentry);
+       if (IS_ERR(h_path.dentry))
+               goto out;
+
+       err = 0;
+       if (h_path.dentry->d_inode) {
+               h_path.mnt = br->br_mnt;
+               err = au_wh_unlink_dentry(au_h_iptr(dir, bdst), &h_path,
+                                         dentry);
+       }
+       dput(h_path.dentry);
+
+ out:
+       return err;
+}
+
+static int au_cpdown_dir(struct dentry *dentry, aufs_bindex_t bdst,
+                        struct dentry *h_parent, void *arg)
+{
+       int err, rerr;
+       aufs_bindex_t bend, bopq, bstart;
+       unsigned char parent_opq;
+       struct path h_path;
+       struct dentry *parent;
+       struct inode *h_dir, *h_inode, *inode, *dir;
+       struct au_cpdown_dir_args *args = arg;
+
+       bstart = au_dbstart(dentry);
+       /* dentry is di-locked */
+       parent = dget_parent(dentry);
+       dir = parent->d_inode;
+       h_dir = h_parent->d_inode;
+       AuDebugOn(h_dir != au_h_iptr(dir, bdst));
+       IMustLock(h_dir);
+
+       err = au_lkup_neg(dentry, bdst);
+       if (unlikely(err < 0))
+               goto out;
+       h_path.dentry = au_h_dptr(dentry, bdst);
+       h_path.mnt = au_sbr_mnt(dentry->d_sb, bdst);
+       err = vfsub_sio_mkdir(au_h_iptr(dir, bdst), &h_path,
+                             S_IRWXU | S_IRUGO | S_IXUGO);
+       if (unlikely(err))
+               goto out_put;
+       au_fset_cpdown(args->flags, MADE_DIR);
+
+       bend = au_dbend(dentry);
+       bopq = au_dbdiropq(dentry);
+       au_fclr_cpdown(args->flags, WHED);
+       au_fclr_cpdown(args->flags, DIROPQ);
+       if (au_dbwh(dentry) == bdst)
+               au_fset_cpdown(args->flags, WHED);
+       if (!au_ftest_cpdown(args->flags, PARENT_OPQ) && bopq <= bdst)
+               au_fset_cpdown(args->flags, PARENT_OPQ);
+       parent_opq = (au_ftest_cpdown(args->flags, PARENT_OPQ)
+                     && args->parent == dentry);
+       h_inode = h_path.dentry->d_inode;
+       mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+       if (au_ftest_cpdown(args->flags, WHED)) {
+               err = au_cpdown_dir_opq(dentry, bdst, args);
+               if (unlikely(err)) {
+                       mutex_unlock(&h_inode->i_mutex);
+                       goto out_dir;
+               }
+       }
+
+       err = au_cpdown_attr(&h_path, au_h_dptr(dentry, bstart));
+       mutex_unlock(&h_inode->i_mutex);
+       if (unlikely(err))
+               goto out_opq;
+
+       if (au_ftest_cpdown(args->flags, WHED)) {
+               err = au_cpdown_dir_wh(dentry, h_parent, dir, bdst);
+               if (unlikely(err))
+                       goto out_opq;
+       }
+
+       inode = dentry->d_inode;
+       if (au_ibend(inode) < bdst)
+               au_set_ibend(inode, bdst);
+       au_set_h_iptr(inode, bdst, au_igrab(h_inode),
+                     au_hi_flags(inode, /*isdir*/1));
+       goto out; /* success */
+
+       /* revert */
+ out_opq:
+       if (au_ftest_cpdown(args->flags, DIROPQ)) {
+               mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+               rerr = au_diropq_remove(dentry, bdst);
+               mutex_unlock(&h_inode->i_mutex);
+               if (unlikely(rerr)) {
+                       AuIOErr("failed removing diropq for %.*s b%d (%d)\n",
+                               AuDLNPair(dentry), bdst, rerr);
+                       err = -EIO;
+                       goto out;
+               }
+       }
+ out_dir:
+       if (au_ftest_cpdown(args->flags, MADE_DIR)) {
+               rerr = vfsub_sio_rmdir(au_h_iptr(dir, bdst), &h_path);
+               if (unlikely(rerr)) {
+                       AuIOErr("failed removing %.*s b%d (%d)\n",
+                               AuDLNPair(dentry), bdst, rerr);
+                       err = -EIO;
+               }
+       }
+ out_put:
+       au_set_h_dptr(dentry, bdst, NULL);
+       if (au_dbend(dentry) == bdst)
+               au_update_dbend(dentry);
+ out:
+       dput(parent);
+       return err;
+}
+
+int au_cpdown_dirs(struct dentry *dentry, aufs_bindex_t bdst)
+{
+       int err;
+       struct au_cpdown_dir_args args = {
+               .parent = dget_parent(dentry),
+               .flags  = 0
+       };
+
+       err = au_cp_dirs(dentry, bdst, au_cpdown_dir, &args);
+       dput(args.parent);
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* policies for create */
+
+static int au_wbr_bu(struct super_block *sb, aufs_bindex_t bindex)
+{
+       for (; bindex >= 0; bindex--)
+               if (!au_br_rdonly(au_sbr(sb, bindex)))
+                       return bindex;
+       return -EROFS;
+}
+
+/* top down parent */
+static int au_wbr_create_tdp(struct dentry *dentry, int isdir __maybe_unused)
+{
+       int err;
+       aufs_bindex_t bstart, bindex;
+       struct super_block *sb;
+       struct dentry *parent, *h_parent;
+
+       sb = dentry->d_sb;
+       bstart = au_dbstart(dentry);
+       err = bstart;
+       if (!au_br_rdonly(au_sbr(sb, bstart)))
+               goto out;
+
+       err = -EROFS;
+       parent = dget_parent(dentry);
+       for (bindex = au_dbstart(parent); bindex < bstart; bindex++) {
+               h_parent = au_h_dptr(parent, bindex);
+               if (!h_parent || !h_parent->d_inode)
+                       continue;
+
+               if (!au_br_rdonly(au_sbr(sb, bindex))) {
+                       err = bindex;
+                       break;
+               }
+       }
+       dput(parent);
+
+       /* bottom up here */
+       if (unlikely(err < 0))
+               err = au_wbr_bu(sb, bstart - 1);
+
+ out:
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* an exception for the policy other than tdp */
+static int au_wbr_create_exp(struct dentry *dentry)
+{
+       int err;
+       aufs_bindex_t bwh, bdiropq;
+       struct dentry *parent;
+
+       err = -1;
+       bwh = au_dbwh(dentry);
+       parent = dget_parent(dentry);
+       bdiropq = au_dbdiropq(parent);
+       if (bwh >= 0) {
+               if (bdiropq >= 0)
+                       err = min(bdiropq, bwh);
+               else
+                       err = bwh;
+               AuDbg("%d\n", err);
+       } else if (bdiropq >= 0) {
+               err = bdiropq;
+               AuDbg("%d\n", err);
+       }
+       dput(parent);
+
+       if (err >= 0 && au_br_rdonly(au_sbr(dentry->d_sb, err)))
+               err = -1;
+
+       AuDbg("%d\n", err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* round robin */
+static int au_wbr_create_init_rr(struct super_block *sb)
+{
+       int err;
+
+       err = au_wbr_bu(sb, au_sbend(sb));
+       atomic_set(&au_sbi(sb)->si_wbr_rr_next, -err); /* less important */
+
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+static int au_wbr_create_rr(struct dentry *dentry, int isdir)
+{
+       int err, nbr;
+       unsigned int u;
+       aufs_bindex_t bindex, bend;
+       struct super_block *sb;
+       atomic_t *next;
+
+       err = au_wbr_create_exp(dentry);
+       if (err >= 0)
+               goto out;
+
+       sb = dentry->d_sb;
+       next = &au_sbi(sb)->si_wbr_rr_next;
+       bend = au_sbend(sb);
+       nbr = bend + 1;
+       for (bindex = 0; bindex <= bend; bindex++) {
+               if (!isdir) {
+                       err = atomic_dec_return(next) + 1;
+                       /* modulo for 0 is meaningless */
+                       if (unlikely(!err))
+                               err = atomic_dec_return(next) + 1;
+               } else
+                       err = atomic_read(next);
+               AuDbg("%d\n", err);
+               u = err;
+               err = u % nbr;
+               AuDbg("%d\n", err);
+               if (!au_br_rdonly(au_sbr(sb, err)))
+                       break;
+               err = -EROFS;
+       }
+
+ out:
+       AuDbg("%d\n", err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* most free space */
+static void au_mfs(struct dentry *dentry)
+{
+       struct super_block *sb;
+       struct au_branch *br;
+       struct au_wbr_mfs *mfs;
+       aufs_bindex_t bindex, bend;
+       int err;
+       unsigned long long b, bavail;
+       /* reduce the stack usage */
+       struct kstatfs *st;
+
+       st = kmalloc(sizeof(*st), GFP_NOFS);
+       if (unlikely(!st)) {
+               AuWarn1("failed updating mfs(%d), ignored\n", -ENOMEM);
+               return;
+       }
+
+       bavail = 0;
+       sb = dentry->d_sb;
+       mfs = &au_sbi(sb)->si_wbr_mfs;
+       mfs->mfs_bindex = -EROFS;
+       mfs->mfsrr_bytes = 0;
+       bend = au_sbend(sb);
+       for (bindex = 0; bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               if (au_br_rdonly(br))
+                       continue;
+
+               /* sb->s_root for NFS is unreliable */
+               err = vfs_statfs(br->br_mnt->mnt_root, st);
+               if (unlikely(err)) {
+                       AuWarn1("failed statfs, b%d, %d\n", bindex, err);
+                       continue;
+               }
+
+               /* when the available size is equal, select the lower one */
+               BUILD_BUG_ON(sizeof(b) < sizeof(st->f_bavail)
+                            || sizeof(b) < sizeof(st->f_bsize));
+               b = st->f_bavail * st->f_bsize;
+               br->br_wbr->wbr_bytes = b;
+               if (b >= bavail) {
+                       bavail = b;
+                       mfs->mfs_bindex = bindex;
+                       mfs->mfs_jiffy = jiffies;
+               }
+       }
+
+       mfs->mfsrr_bytes = bavail;
+       AuDbg("b%d\n", mfs->mfs_bindex);
+       kfree(st);
+}
+
+static int au_wbr_create_mfs(struct dentry *dentry, int isdir __maybe_unused)
+{
+       int err;
+       struct super_block *sb;
+       struct au_wbr_mfs *mfs;
+
+       err = au_wbr_create_exp(dentry);
+       if (err >= 0)
+               goto out;
+
+       sb = dentry->d_sb;
+       mfs = &au_sbi(sb)->si_wbr_mfs;
+       mutex_lock(&mfs->mfs_lock);
+       if (time_after(jiffies, mfs->mfs_jiffy + mfs->mfs_expire)
+           || mfs->mfs_bindex < 0
+           || au_br_rdonly(au_sbr(sb, mfs->mfs_bindex)))
+               au_mfs(dentry);
+       mutex_unlock(&mfs->mfs_lock);
+       err = mfs->mfs_bindex;
+
+ out:
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+static int au_wbr_create_init_mfs(struct super_block *sb)
+{
+       struct au_wbr_mfs *mfs;
+
+       mfs = &au_sbi(sb)->si_wbr_mfs;
+       mutex_init(&mfs->mfs_lock);
+       mfs->mfs_jiffy = 0;
+       mfs->mfs_bindex = -EROFS;
+
+       return 0;
+}
+
+static int au_wbr_create_fin_mfs(struct super_block *sb __maybe_unused)
+{
+       mutex_destroy(&au_sbi(sb)->si_wbr_mfs.mfs_lock);
+       return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* most free space and then round robin */
+static int au_wbr_create_mfsrr(struct dentry *dentry, int isdir)
+{
+       int err;
+       struct au_wbr_mfs *mfs;
+
+       err = au_wbr_create_mfs(dentry, isdir);
+       if (err >= 0) {
+               mfs = &au_sbi(dentry->d_sb)->si_wbr_mfs;
+               if (mfs->mfsrr_bytes < mfs->mfsrr_watermark)
+                       err = au_wbr_create_rr(dentry, isdir);
+       }
+
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+static int au_wbr_create_init_mfsrr(struct super_block *sb)
+{
+       int err;
+
+       au_wbr_create_init_mfs(sb); /* ignore */
+       err = au_wbr_create_init_rr(sb);
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* top down parent and most free space */
+static int au_wbr_create_pmfs(struct dentry *dentry, int isdir)
+{
+       int err, e2;
+       unsigned long long b;
+       aufs_bindex_t bindex, bstart, bend;
+       struct super_block *sb;
+       struct dentry *parent, *h_parent;
+       struct au_branch *br;
+
+       err = au_wbr_create_tdp(dentry, isdir);
+       if (unlikely(err < 0))
+               goto out;
+       parent = dget_parent(dentry);
+       bstart = au_dbstart(parent);
+       bend = au_dbtaildir(parent);
+       if (bstart == bend)
+               goto out_parent; /* success */
+
+       e2 = au_wbr_create_mfs(dentry, isdir);
+       if (e2 < 0)
+               goto out_parent; /* success */
+
+       /* when the available size is equal, select upper one */
+       sb = dentry->d_sb;
+       br = au_sbr(sb, err);
+       b = br->br_wbr->wbr_bytes;
+       AuDbg("b%d, %llu\n", err, b);
+
+       for (bindex = bstart; bindex <= bend; bindex++) {
+               h_parent = au_h_dptr(parent, bindex);
+               if (!h_parent || !h_parent->d_inode)
+                       continue;
+
+               br = au_sbr(sb, bindex);
+               if (!au_br_rdonly(br) && br->br_wbr->wbr_bytes > b) {
+                       b = br->br_wbr->wbr_bytes;
+                       err = bindex;
+                       AuDbg("b%d, %llu\n", err, b);
+               }
+       }
+
+ out_parent:
+       dput(parent);
+ out:
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* policies for copyup */
+
+/* top down parent */
+static int au_wbr_copyup_tdp(struct dentry *dentry)
+{
+       return au_wbr_create_tdp(dentry, /*isdir, anything is ok*/0);
+}
+
+/* bottom up parent */
+static int au_wbr_copyup_bup(struct dentry *dentry)
+{
+       int err;
+       aufs_bindex_t bindex, bstart;
+       struct dentry *parent, *h_parent;
+       struct super_block *sb;
+
+       err = -EROFS;
+       sb = dentry->d_sb;
+       parent = dget_parent(dentry);
+       bstart = au_dbstart(parent);
+       for (bindex = au_dbstart(dentry); bindex >= bstart; bindex--) {
+               h_parent = au_h_dptr(parent, bindex);
+               if (!h_parent || !h_parent->d_inode)
+                       continue;
+
+               if (!au_br_rdonly(au_sbr(sb, bindex))) {
+                       err = bindex;
+                       break;
+               }
+       }
+       dput(parent);
+
+       /* bottom up here */
+       if (unlikely(err < 0))
+               err = au_wbr_bu(sb, bstart - 1);
+
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+/* bottom up */
+static int au_wbr_copyup_bu(struct dentry *dentry)
+{
+       int err;
+
+       err = au_wbr_bu(dentry->d_sb, au_dbstart(dentry));
+
+       AuDbg("b%d\n", err);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct au_wbr_copyup_operations au_wbr_copyup_ops[] = {
+       [AuWbrCopyup_TDP] = {
+               .copyup = au_wbr_copyup_tdp
+       },
+       [AuWbrCopyup_BUP] = {
+               .copyup = au_wbr_copyup_bup
+       },
+       [AuWbrCopyup_BU] = {
+               .copyup = au_wbr_copyup_bu
+       }
+};
+
+struct au_wbr_create_operations au_wbr_create_ops[] = {
+       [AuWbrCreate_TDP] = {
+               .create = au_wbr_create_tdp
+       },
+       [AuWbrCreate_RR] = {
+               .create = au_wbr_create_rr,
+               .init   = au_wbr_create_init_rr
+       },
+       [AuWbrCreate_MFS] = {
+               .create = au_wbr_create_mfs,
+               .init   = au_wbr_create_init_mfs,
+               .fin    = au_wbr_create_fin_mfs
+       },
+       [AuWbrCreate_MFSV] = {
+               .create = au_wbr_create_mfs,
+               .init   = au_wbr_create_init_mfs,
+               .fin    = au_wbr_create_fin_mfs
+       },
+       [AuWbrCreate_MFSRR] = {
+               .create = au_wbr_create_mfsrr,
+               .init   = au_wbr_create_init_mfsrr,
+               .fin    = au_wbr_create_fin_mfs
+       },
+       [AuWbrCreate_MFSRRV] = {
+               .create = au_wbr_create_mfsrr,
+               .init   = au_wbr_create_init_mfsrr,
+               .fin    = au_wbr_create_fin_mfs
+       },
+       [AuWbrCreate_PMFS] = {
+               .create = au_wbr_create_pmfs,
+               .init   = au_wbr_create_init_mfs,
+               .fin    = au_wbr_create_fin_mfs
+       },
+       [AuWbrCreate_PMFSV] = {
+               .create = au_wbr_create_pmfs,
+               .init   = au_wbr_create_init_mfs,
+               .fin    = au_wbr_create_fin_mfs
+       }
+};
diff --git a/fs/aufs/whout.c b/fs/aufs/whout.c
new file mode 100644
index 0000000..a45e126
--- /dev/null
+++ b/fs/aufs/whout.c
@@ -0,0 +1,1030 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * whiteout for logical deletion and opaque directory
+ */
+
+#include <linux/fs.h>
+#include "aufs.h"
+
+#define WH_MASK                        S_IRUGO
+
+/*
+ * If a directory contains this file, then it is opaque.  We start with the
+ * .wh. flag so that it is blocked by lookup.
+ */
+static struct qstr diropq_name = {
+       .name = AUFS_WH_DIROPQ,
+       .len = sizeof(AUFS_WH_DIROPQ) - 1
+};
+
+/*
+ * generate whiteout name, which is NOT terminated by NULL.
+ * @name: original d_name.name
+ * @len: original d_name.len
+ * @wh: whiteout qstr
+ * returns zero when succeeds, otherwise error.
+ * succeeded value as wh->name should be freed by kfree().
+ */
+int au_wh_name_alloc(struct qstr *wh, const struct qstr *name)
+{
+       char *p;
+
+       if (unlikely(name->len > PATH_MAX - AUFS_WH_PFX_LEN))
+               return -ENAMETOOLONG;
+
+       wh->len = name->len + AUFS_WH_PFX_LEN;
+       p = kmalloc(wh->len, GFP_NOFS);
+       wh->name = p;
+       if (p) {
+               memcpy(p, AUFS_WH_PFX, AUFS_WH_PFX_LEN);
+               memcpy(p + AUFS_WH_PFX_LEN, name->name, name->len);
+               /* smp_mb(); */
+               return 0;
+       }
+       return -ENOMEM;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * test if the @wh_name exists under @h_parent.
+ * @try_sio specifies the necessary of super-io.
+ */
+int au_wh_test(struct dentry *h_parent, struct qstr *wh_name,
+              struct au_branch *br, int try_sio)
+{
+       int err;
+       struct dentry *wh_dentry;
+       struct inode *h_dir;
+
+       h_dir = h_parent->d_inode;
+       if (!try_sio)
+               wh_dentry = au_lkup_one(wh_name, h_parent, br, /*nd*/NULL);
+       else
+               wh_dentry = au_sio_lkup_one(wh_name, h_parent, br);
+       err = PTR_ERR(wh_dentry);
+       if (IS_ERR(wh_dentry))
+               goto out;
+
+       err = 0;
+       if (!wh_dentry->d_inode)
+               goto out_wh; /* success */
+
+       err = 1;
+       if (S_ISREG(wh_dentry->d_inode->i_mode))
+               goto out_wh; /* success */
+
+       err = -EIO;
+       AuIOErr("%.*s Invalid whiteout entry type 0%o.\n",
+               AuDLNPair(wh_dentry), wh_dentry->d_inode->i_mode);
+
+ out_wh:
+       dput(wh_dentry);
+ out:
+       return err;
+}
+
+/*
+ * test if the @h_dentry sets opaque or not.
+ */
+int au_diropq_test(struct dentry *h_dentry, struct au_branch *br)
+{
+       int err;
+       struct inode *h_dir;
+
+       h_dir = h_dentry->d_inode;
+       err = au_wh_test(h_dentry, &diropq_name, br,
+                        au_test_h_perm_sio(h_dir, MAY_EXEC));
+       return err;
+}
+
+/*
+ * returns a negative dentry whose name is unique and temporary.
+ */
+struct dentry *au_whtmp_lkup(struct dentry *h_parent, struct au_branch *br,
+                            struct qstr *prefix)
+{
+#define HEX_LEN        4
+       struct dentry *dentry;
+       int i;
+       char defname[AUFS_WH_PFX_LEN * 2 + DNAME_INLINE_LEN_MIN + 1
+                    + HEX_LEN + 1], *name, *p;
+       static unsigned short cnt;
+       struct qstr qs;
+
+       name = defname;
+       qs.len = sizeof(defname) - DNAME_INLINE_LEN_MIN + prefix->len - 1;
+       if (unlikely(prefix->len > DNAME_INLINE_LEN_MIN)) {
+               dentry = ERR_PTR(-ENAMETOOLONG);
+               if (unlikely(qs.len >= PATH_MAX))
+                       goto out;
+               dentry = ERR_PTR(-ENOMEM);
+               name = kmalloc(qs.len + 1, GFP_NOFS);
+               if (unlikely(!name))
+                       goto out;
+       }
+
+       /* doubly whiteout-ed */
+       memcpy(name, AUFS_WH_PFX AUFS_WH_PFX, AUFS_WH_PFX_LEN * 2);
+       p = name + AUFS_WH_PFX_LEN * 2;
+       memcpy(p, prefix->name, prefix->len);
+       p += prefix->len;
+       *p++ = '.';
+       AuDebugOn(name + qs.len + 1 - p <= HEX_LEN);
+
+       qs.name = name;
+       for (i = 0; i < 3; i++) {
+               sprintf(p, "%.*d", HEX_LEN, cnt++);
+               dentry = au_sio_lkup_one(&qs, h_parent, br);
+               if (IS_ERR(dentry) || !dentry->d_inode)
+                       goto out_name;
+               dput(dentry);
+       }
+       /* AuWarn("could not get random name\n"); */
+       dentry = ERR_PTR(-EEXIST);
+       AuDbg("%.*s\n", AuLNPair(&qs));
+       BUG();
+
+ out_name:
+       if (name != defname)
+               kfree(name);
+ out:
+       return dentry;
+#undef HEX_LEN
+}
+
+/*
+ * rename the @h_dentry on @br to the whiteouted temporary name.
+ */
+int au_whtmp_ren(struct dentry *h_dentry, struct au_branch *br)
+{
+       int err;
+       struct path h_path = {
+               .mnt = br->br_mnt
+       };
+       struct inode *h_dir;
+       struct dentry *h_parent;
+
+       h_parent = h_dentry->d_parent; /* dir inode is locked */
+       h_dir = h_parent->d_inode;
+       IMustLock(h_dir);
+
+       h_path.dentry = au_whtmp_lkup(h_parent, br, &h_dentry->d_name);
+       err = PTR_ERR(h_path.dentry);
+       if (IS_ERR(h_path.dentry))
+               goto out;
+
+       /* under the same dir, no need to lock_rename() */
+       err = vfsub_rename(h_dir, h_dentry, h_dir, &h_path);
+       AuTraceErr(err);
+       dput(h_path.dentry);
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+/*
+ * functions for removing a whiteout
+ */
+
+static int do_unlink_wh(struct inode *h_dir, struct path *h_path)
+{
+       int force;
+
+       /*
+        * forces superio when the dir has a sticky bit.
+        * this may be a violation of unix fs semantics.
+        */
+       force = (h_dir->i_mode & S_ISVTX)
+               && h_path->dentry->d_inode->i_uid != current_fsuid();
+       return vfsub_unlink(h_dir, h_path, force);
+}
+
+int au_wh_unlink_dentry(struct inode *h_dir, struct path *h_path,
+                       struct dentry *dentry)
+{
+       int err;
+
+       err = do_unlink_wh(h_dir, h_path);
+       if (!err && dentry)
+               au_set_dbwh(dentry, -1);
+
+       return err;
+}
+
+static int unlink_wh_name(struct dentry *h_parent, struct qstr *wh,
+                         struct au_branch *br)
+{
+       int err;
+       struct path h_path = {
+               .mnt = br->br_mnt
+       };
+
+       err = 0;
+       h_path.dentry = au_lkup_one(wh, h_parent, br, /*nd*/NULL);
+       if (IS_ERR(h_path.dentry))
+               err = PTR_ERR(h_path.dentry);
+       else {
+               if (h_path.dentry->d_inode
+                   && S_ISREG(h_path.dentry->d_inode->i_mode))
+                       err = do_unlink_wh(h_parent->d_inode, &h_path);
+               dput(h_path.dentry);
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+/*
+ * initialize/clean whiteout for a branch
+ */
+
+static void au_wh_clean(struct inode *h_dir, struct path *whpath,
+                       const int isdir)
+{
+       int err;
+
+       if (!whpath->dentry->d_inode)
+               return;
+
+       err = mnt_want_write(whpath->mnt);
+       if (!err) {
+               if (isdir)
+                       err = vfsub_rmdir(h_dir, whpath);
+               else
+                       err = vfsub_unlink(h_dir, whpath, /*force*/0);
+               mnt_drop_write(whpath->mnt);
+       }
+       if (unlikely(err))
+               AuWarn("failed removing %.*s (%d), ignored.\n",
+                      AuDLNPair(whpath->dentry), err);
+}
+
+static int test_linkable(struct dentry *h_root)
+{
+       struct inode *h_dir = h_root->d_inode;
+
+       if (h_dir->i_op->link)
+               return 0;
+
+       AuErr("%.*s (%s) doesn't support link(2), use noplink and rw+nolwh\n",
+             AuDLNPair(h_root), au_sbtype(h_root->d_sb));
+       return -ENOSYS;
+}
+
+/* todo: should this mkdir be done in /sbin/mount.aufs helper? */
+static int au_whdir(struct inode *h_dir, struct path *path)
+{
+       int err;
+
+       err = -EEXIST;
+       if (!path->dentry->d_inode) {
+               int mode = S_IRWXU;
+
+               if (au_test_nfs(path->dentry->d_sb))
+                       mode |= S_IXUGO;
+               err = mnt_want_write(path->mnt);
+               if (!err) {
+                       err = vfsub_mkdir(h_dir, path, mode);
+                       mnt_drop_write(path->mnt);
+               }
+       } else if (S_ISDIR(path->dentry->d_inode->i_mode))
+               err = 0;
+       else
+               AuErr("unknown %.*s exists\n", AuDLNPair(path->dentry));
+
+       return err;
+}
+
+struct au_wh_base {
+       const struct qstr *name;
+       struct dentry *dentry;
+};
+
+static void au_wh_init_ro(struct inode *h_dir, struct au_wh_base base[],
+                         struct path *h_path)
+{
+       h_path->dentry = base[AuBrWh_BASE].dentry;
+       au_wh_clean(h_dir, h_path, /*isdir*/0);
+       h_path->dentry = base[AuBrWh_PLINK].dentry;
+       au_wh_clean(h_dir, h_path, /*isdir*/1);
+       h_path->dentry = base[AuBrWh_ORPH].dentry;
+       au_wh_clean(h_dir, h_path, /*isdir*/1);
+}
+
+/*
+ * returns tri-state,
+ * minus: error, caller should print the mesage
+ * zero: succuess
+ * plus: error, caller should NOT print the mesage
+ */
+static int au_wh_init_rw_nolink(struct dentry *h_root, struct au_wbr *wbr,
+                               int do_plink, struct au_wh_base base[],
+                               struct path *h_path)
+{
+       int err;
+       struct inode *h_dir;
+
+       h_dir = h_root->d_inode;
+       h_path->dentry = base[AuBrWh_BASE].dentry;
+       au_wh_clean(h_dir, h_path, /*isdir*/0);
+       h_path->dentry = base[AuBrWh_PLINK].dentry;
+       if (do_plink) {
+               err = test_linkable(h_root);
+               if (unlikely(err)) {
+                       err = 1;
+                       goto out;
+               }
+
+               err = au_whdir(h_dir, h_path);
+               if (unlikely(err))
+                       goto out;
+               wbr->wbr_plink = dget(base[AuBrWh_PLINK].dentry);
+       } else
+               au_wh_clean(h_dir, h_path, /*isdir*/1);
+       h_path->dentry = base[AuBrWh_ORPH].dentry;
+       err = au_whdir(h_dir, h_path);
+       if (unlikely(err))
+               goto out;
+       wbr->wbr_orph = dget(base[AuBrWh_ORPH].dentry);
+
+ out:
+       return err;
+}
+
+/*
+ * for the moment, aufs supports the branch filesystem which does not support
+ * link(2). testing on FAT which does not support i_op->setattr() fully either,
+ * copyup failed. finally, such filesystem will not be used as the writable
+ * branch.
+ *
+ * returns tri-state, see above.
+ */
+static int au_wh_init_rw(struct dentry *h_root, struct au_wbr *wbr,
+                        int do_plink, struct au_wh_base base[],
+                        struct path *h_path)
+{
+       int err;
+       struct inode *h_dir;
+
+       err = test_linkable(h_root);
+       if (unlikely(err)) {
+               err = 1;
+               goto out;
+       }
+
+       /*
+        * todo: should this create be done in /sbin/mount.aufs helper?
+        */
+       err = -EEXIST;
+       h_dir = h_root->d_inode;
+       if (!base[AuBrWh_BASE].dentry->d_inode) {
+               err = mnt_want_write(h_path->mnt);
+               if (!err) {
+                       h_path->dentry = base[AuBrWh_BASE].dentry;
+                       err = vfsub_create(h_dir, h_path, WH_MASK);
+                       mnt_drop_write(h_path->mnt);
+               }
+       } else if (S_ISREG(base[AuBrWh_BASE].dentry->d_inode->i_mode))
+               err = 0;
+       else
+               AuErr("unknown %.*s/%.*s exists\n",
+                     AuDLNPair(h_root), AuDLNPair(base[AuBrWh_BASE].dentry));
+       if (unlikely(err))
+               goto out;
+
+       h_path->dentry = base[AuBrWh_PLINK].dentry;
+       if (do_plink) {
+               err = au_whdir(h_dir, h_path);
+               if (unlikely(err))
+                       goto out;
+               wbr->wbr_plink = dget(base[AuBrWh_PLINK].dentry);
+       } else
+               au_wh_clean(h_dir, h_path, /*isdir*/1);
+       wbr->wbr_whbase = dget(base[AuBrWh_BASE].dentry);
+
+       h_path->dentry = base[AuBrWh_ORPH].dentry;
+       err = au_whdir(h_dir, h_path);
+       if (unlikely(err))
+               goto out;
+       wbr->wbr_orph = dget(base[AuBrWh_ORPH].dentry);
+
+ out:
+       return err;
+}
+
+/*
+ * initialize the whiteout base file/dir for @br.
+ */
+int au_wh_init(struct dentry *h_root, struct au_branch *br,
+              struct super_block *sb)
+{
+       int err, i;
+       const unsigned char do_plink
+               = !!au_opt_test(au_mntflags(sb), PLINK);
+       struct path path = {
+               .mnt = br->br_mnt
+       };
+       struct inode *h_dir;
+       struct au_wbr *wbr = br->br_wbr;
+       static const struct qstr base_name[] = {
+               [AuBrWh_BASE] = {
+                       .name   = AUFS_BASE_NAME,
+                       .len    = sizeof(AUFS_BASE_NAME) - 1
+               },
+               [AuBrWh_PLINK] = {
+                       .name   = AUFS_PLINKDIR_NAME,
+                       .len    = sizeof(AUFS_PLINKDIR_NAME) - 1
+               },
+               [AuBrWh_ORPH] = {
+                       .name   = AUFS_ORPHDIR_NAME,
+                       .len    = sizeof(AUFS_ORPHDIR_NAME) - 1
+               }
+       };
+       struct au_wh_base base[] = {
+               [AuBrWh_BASE] = {
+                       .name   = base_name + AuBrWh_BASE,
+                       .dentry = NULL
+               },
+               [AuBrWh_PLINK] = {
+                       .name   = base_name + AuBrWh_PLINK,
+                       .dentry = NULL
+               },
+               [AuBrWh_ORPH] = {
+                       .name   = base_name + AuBrWh_ORPH,
+                       .dentry = NULL
+               }
+       };
+
+
+       h_dir = h_root->d_inode;
+       for (i = 0; i < AuBrWh_Last; i++) {
+               /* doubly whiteouted */
+               struct dentry *d;
+
+               d = au_wh_lkup(h_root, (void *)base[i].name, br);
+               err = PTR_ERR(d);
+               if (IS_ERR(d))
+                       goto out;
+
+               base[i].dentry = d;
+               AuDebugOn(wbr
+                         && wbr->wbr_wh[i]
+                         && wbr->wbr_wh[i] != base[i].dentry);
+       }
+
+       if (wbr)
+               for (i = 0; i < AuBrWh_Last; i++) {
+                       dput(wbr->wbr_wh[i]);
+                       wbr->wbr_wh[i] = NULL;
+               }
+
+       err = 0;
+
+       switch (br->br_perm) {
+       case AuBrPerm_RO:
+       case AuBrPerm_ROWH:
+       case AuBrPerm_RR:
+       case AuBrPerm_RRWH:
+               au_wh_init_ro(h_dir, base, &path);
+               break;
+
+       case AuBrPerm_RWNoLinkWH:
+               err = au_wh_init_rw_nolink(h_root, wbr, do_plink, base, &path);
+               if (err > 0)
+                       goto out;
+               else if (err)
+                       goto out_err;
+               break;
+
+       case AuBrPerm_RW:
+               err = au_wh_init_rw(h_root, wbr, do_plink, base, &path);
+               if (err > 0)
+                       goto out;
+               else if (err)
+                       goto out_err;
+               break;
+
+       default:
+               BUG();
+       }
+       goto out; /* success */
+
+ out_err:
+       AuErr("an error(%d) on the writable branch %.*s(%s)\n",
+             err, AuDLNPair(h_root), au_sbtype(h_root->d_sb));
+ out:
+       for (i = 0; i < AuBrWh_Last; i++)
+               dput(base[i].dentry);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+/*
+ * whiteouts are all hard-linked usually.
+ * when its link count reaches a ceiling, we create a new whiteout base
+ * asynchronously.
+ */
+
+struct reinit_br_wh {
+       struct super_block *sb;
+       struct au_branch *br;
+};
+
+static void reinit_br_wh(void *arg)
+{
+       int err;
+       aufs_bindex_t bindex;
+       struct path h_path;
+       struct reinit_br_wh *a = arg;
+       struct au_wbr *wbr;
+       struct inode *dir;
+       struct dentry *h_root;
+       struct au_hinode *hdir;
+
+       err = 0;
+       wbr = a->br->br_wbr;
+       /* big aufs lock */
+       si_noflush_write_lock(a->sb);
+       if (!au_br_writable(a->br->br_perm))
+               goto out;
+       bindex = au_br_index(a->sb, a->br->br_id);
+       if (unlikely(bindex < 0))
+               goto out;
+
+       dir = a->sb->s_root->d_inode;
+       /* ii_read_lock_parent(dir); */
+       hdir = au_hi(dir, bindex);
+       h_root = au_h_dptr(a->sb->s_root, bindex);
+
+       au_hin_imtx_lock_nested(hdir, AuLsc_I_PARENT);
+       wbr_wh_write_lock(wbr);
+       err = au_h_verify(wbr->wbr_whbase, au_opt_udba(a->sb), hdir->hi_inode,
+                         h_root, a->br);
+       if (!err) {
+               err = mnt_want_write(a->br->br_mnt);
+               if (!err) {
+                       h_path.dentry = wbr->wbr_whbase;
+                       h_path.mnt = a->br->br_mnt;
+                       err = vfsub_unlink(hdir->hi_inode, &h_path, /*force*/0);
+                       mnt_drop_write(a->br->br_mnt);
+               }
+       } else {
+               AuWarn("%.*s is moved, ignored\n", AuDLNPair(wbr->wbr_whbase));
+               err = 0;
+       }
+       dput(wbr->wbr_whbase);
+       wbr->wbr_whbase = NULL;
+       if (!err)
+               err = au_wh_init(h_root, a->br, a->sb);
+       wbr_wh_write_unlock(wbr);
+       au_hin_imtx_unlock(hdir);
+       /* ii_read_unlock(dir); */
+
+ out:
+       if (wbr)
+               atomic_dec(&wbr->wbr_wh_running);
+       atomic_dec(&a->br->br_count);
+       au_nwt_done(&au_sbi(a->sb)->si_nowait);
+       si_write_unlock(a->sb);
+       kfree(arg);
+       if (unlikely(err))
+               AuIOErr("err %d\n", err);
+}
+
+static void kick_reinit_br_wh(struct super_block *sb, struct au_branch *br)
+{
+       int do_dec, wkq_err;
+       struct reinit_br_wh *arg;
+
+       do_dec = 1;
+       if (atomic_inc_return(&br->br_wbr->wbr_wh_running) != 1)
+               goto out;
+
+       /* ignore ENOMEM */
+       arg = kmalloc(sizeof(*arg), GFP_NOFS);
+       if (arg) {
+               /*
+                * dec(wh_running), kfree(arg) and dec(br_count)
+                * in reinit function
+                */
+               arg->sb = sb;
+               arg->br = br;
+               atomic_inc(&br->br_count);
+               wkq_err = au_wkq_nowait(reinit_br_wh, arg, sb);
+               if (unlikely(wkq_err)) {
+                       atomic_dec(&br->br_wbr->wbr_wh_running);
+                       atomic_dec(&br->br_count);
+                       kfree(arg);
+               }
+               do_dec = 0;
+       }
+
+ out:
+       if (do_dec)
+               atomic_dec(&br->br_wbr->wbr_wh_running);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * create the whiteout @wh.
+ */
+static int link_or_create_wh(struct super_block *sb, aufs_bindex_t bindex,
+                            struct dentry *wh)
+{
+       int err;
+       struct path h_path = {
+               .dentry = wh
+       };
+       struct au_branch *br;
+       struct au_wbr *wbr;
+       struct dentry *h_parent;
+       struct inode *h_dir;
+
+       h_parent = wh->d_parent; /* dir inode is locked */
+       h_dir = h_parent->d_inode;
+       IMustLock(h_dir);
+
+       br = au_sbr(sb, bindex);
+       h_path.mnt = br->br_mnt;
+       wbr = br->br_wbr;
+       wbr_wh_read_lock(wbr);
+       if (wbr->wbr_whbase) {
+               err = vfsub_link(wbr->wbr_whbase, h_dir, &h_path);
+               if (!err || err != -EMLINK)
+                       goto out;
+
+               /* link count full. re-initialize br_whbase. */
+               kick_reinit_br_wh(sb, br);
+       }
+
+       /* return this error in this context */
+       err = vfsub_create(h_dir, &h_path, WH_MASK);
+
+ out:
+       wbr_wh_read_unlock(wbr);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * create or remove the diropq.
+ */
+static struct dentry *do_diropq(struct dentry *dentry, aufs_bindex_t bindex,
+                               unsigned int flags)
+{
+       struct dentry *opq_dentry, *h_dentry;
+       struct super_block *sb;
+       struct au_branch *br;
+       int err;
+
+       sb = dentry->d_sb;
+       br = au_sbr(sb, bindex);
+       h_dentry = au_h_dptr(dentry, bindex);
+       opq_dentry = au_lkup_one(&diropq_name, h_dentry, br, /*nd*/NULL);
+       if (IS_ERR(opq_dentry))
+               goto out;
+
+       if (au_ftest_diropq(flags, CREATE)) {
+               err = link_or_create_wh(sb, bindex, opq_dentry);
+               if (!err) {
+                       au_set_dbdiropq(dentry, bindex);
+                       goto out; /* success */
+               }
+       } else {
+               struct path tmp = {
+                       .dentry = opq_dentry,
+                       .mnt    = br->br_mnt
+               };
+               err = do_unlink_wh(au_h_iptr(dentry->d_inode, bindex), &tmp);
+               if (!err)
+                       au_set_dbdiropq(dentry, -1);
+       }
+       dput(opq_dentry);
+       opq_dentry = ERR_PTR(err);
+
+ out:
+       return opq_dentry;
+}
+
+struct do_diropq_args {
+       struct dentry **errp;
+       struct dentry *dentry;
+       aufs_bindex_t bindex;
+       unsigned int flags;
+};
+
+static void call_do_diropq(void *args)
+{
+       struct do_diropq_args *a = args;
+       *a->errp = do_diropq(a->dentry, a->bindex, a->flags);
+}
+
+struct dentry *au_diropq_sio(struct dentry *dentry, aufs_bindex_t bindex,
+                            unsigned int flags)
+{
+       struct dentry *diropq, *h_dentry;
+
+       h_dentry = au_h_dptr(dentry, bindex);
+       if (!au_test_h_perm_sio(h_dentry->d_inode, MAY_EXEC | MAY_WRITE))
+               diropq = do_diropq(dentry, bindex, flags);
+       else {
+               int wkq_err;
+               struct do_diropq_args args = {
+                       .errp           = &diropq,
+                       .dentry         = dentry,
+                       .bindex         = bindex,
+                       .flags          = flags
+               };
+
+               wkq_err = au_wkq_wait(call_do_diropq, &args);
+               if (unlikely(wkq_err))
+                       diropq = ERR_PTR(wkq_err);
+       }
+
+       return diropq;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * lookup whiteout dentry.
+ * @h_parent: lower parent dentry which must exist and be locked
+ * @base_name: name of dentry which will be whiteouted
+ * returns dentry for whiteout.
+ */
+struct dentry *au_wh_lkup(struct dentry *h_parent, struct qstr *base_name,
+                         struct au_branch *br)
+{
+       int err;
+       struct qstr wh_name;
+       struct dentry *wh_dentry;
+
+       err = au_wh_name_alloc(&wh_name, base_name);
+       wh_dentry = ERR_PTR(err);
+       if (!err) {
+               wh_dentry = au_lkup_one(&wh_name, h_parent, br, /*nd*/NULL);
+               kfree(wh_name.name);
+       }
+       return wh_dentry;
+}
+
+/*
+ * link/create a whiteout for @dentry on @bindex.
+ */
+struct dentry *au_wh_create(struct dentry *dentry, aufs_bindex_t bindex,
+                           struct dentry *h_parent)
+{
+       struct dentry *wh_dentry;
+       struct super_block *sb;
+       int err;
+
+       sb = dentry->d_sb;
+       wh_dentry = au_wh_lkup(h_parent, &dentry->d_name, au_sbr(sb, bindex));
+       if (!IS_ERR(wh_dentry) && !wh_dentry->d_inode) {
+               err = link_or_create_wh(sb, bindex, wh_dentry);
+               if (!err)
+                       au_set_dbwh(dentry, bindex);
+               else {
+                       dput(wh_dentry);
+                       wh_dentry = ERR_PTR(err);
+               }
+       }
+
+       return wh_dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* Delete all whiteouts in this directory on branch bindex. */
+static int del_wh_children(struct dentry *h_dentry, struct au_nhash *whlist,
+                          aufs_bindex_t bindex, struct au_branch *br)
+{
+       int err;
+       unsigned long ul, n;
+       struct qstr wh_name;
+       char *p;
+       struct hlist_head *head;
+       struct au_vdir_wh *tpos;
+       struct hlist_node *pos;
+       struct au_vdir_destr *str;
+
+       err = -ENOMEM;
+       p = __getname();
+       wh_name.name = p;
+       if (unlikely(!wh_name.name))
+               goto out;
+
+       err = 0;
+       memcpy(p, AUFS_WH_PFX, AUFS_WH_PFX_LEN);
+       p += AUFS_WH_PFX_LEN;
+       n = whlist->nh_num;
+       head = whlist->nh_head;
+       for (ul = 0; !err && ul < n; ul++, head++) {
+               hlist_for_each_entry(tpos, pos, head, wh_hash) {
+                       if (tpos->wh_bindex != bindex)
+                               continue;
+
+                       str = &tpos->wh_str;
+                       if (str->len + AUFS_WH_PFX_LEN <= PATH_MAX) {
+                               memcpy(p, str->name, str->len);
+                               wh_name.len = AUFS_WH_PFX_LEN + str->len;
+                               err = unlink_wh_name(h_dentry, &wh_name, br);
+                               if (!err)
+                                       continue;
+                               break;
+                       }
+                       AuIOErr("whiteout name too long %.*s\n",
+                               str->len, str->name);
+                       err = -EIO;
+                       break;
+               }
+       }
+       __putname(wh_name.name);
+
+ out:
+       return err;
+}
+
+struct del_wh_children_args {
+       int *errp;
+       struct dentry *h_dentry;
+       struct au_nhash *whlist;
+       aufs_bindex_t bindex;
+       struct au_branch *br;
+};
+
+static void call_del_wh_children(void *args)
+{
+       struct del_wh_children_args *a = args;
+       *a->errp = del_wh_children(a->h_dentry, a->whlist, a->bindex, a->br);
+}
+
+/* ---------------------------------------------------------------------- */
+
+struct au_whtmp_rmdir *au_whtmp_rmdir_alloc(struct super_block *sb, gfp_t gfp)
+{
+       struct au_whtmp_rmdir *whtmp;
+
+       whtmp = kmalloc(sizeof(*whtmp), gfp);
+       if (unlikely(!whtmp))
+               goto out;
+
+       whtmp->dir = NULL;
+       whtmp->wh_dentry = NULL;
+       whtmp->whlist = au_nhash_alloc(sb, /*bend*/0, gfp);
+       if (unlikely(!whtmp->whlist))
+               goto out_whtmp;
+       return whtmp; /* success */
+
+ out_whtmp:
+       kfree(whtmp);
+ out:
+       return ERR_PTR(-ENOMEM);
+}
+
+void au_whtmp_rmdir_free(struct au_whtmp_rmdir *whtmp)
+{
+       dput(whtmp->wh_dentry);
+       iput(whtmp->dir);
+       au_nhash_wh_free(whtmp->whlist, /*bend*/0);
+       kfree(whtmp);
+}
+
+/*
+ * rmdir the whiteouted temporary named dir @h_dentry.
+ * @whlist: whiteouted children.
+ */
+int au_whtmp_rmdir(struct inode *dir, aufs_bindex_t bindex,
+                  struct dentry *wh_dentry, struct au_nhash *whlist)
+{
+       int err;
+       struct path h_tmp;
+       struct inode *wh_inode, *h_dir;
+       struct au_branch *br;
+
+       h_dir = wh_dentry->d_parent->d_inode; /* dir inode is locked */
+       IMustLock(h_dir);
+
+       br = au_sbr(dir->i_sb, bindex);
+       wh_inode = wh_dentry->d_inode;
+       mutex_lock_nested(&wh_inode->i_mutex, AuLsc_I_CHILD);
+
+       /*
+        * someone else might change some whiteouts while we were sleeping.
+        * it means this whlist may have an obsoleted entry.
+        */
+       if (!au_test_h_perm_sio(wh_inode, MAY_EXEC | MAY_WRITE))
+               err = del_wh_children(wh_dentry, whlist, bindex, br);
+       else {
+               int wkq_err;
+               struct del_wh_children_args args = {
+                       .errp           = &err,
+                       .h_dentry       = wh_dentry,
+                       .whlist         = whlist,
+                       .bindex         = bindex,
+                       .br             = br
+               };
+
+               wkq_err = au_wkq_wait(call_del_wh_children, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       }
+       mutex_unlock(&wh_inode->i_mutex);
+
+       if (!err) {
+               h_tmp.dentry = wh_dentry;
+               h_tmp.mnt = br->br_mnt;
+               err = vfsub_rmdir(h_dir, &h_tmp);
+               /* d_drop(h_dentry); */
+       }
+
+       if (!err) {
+               if (au_ibstart(dir) == bindex) {
+                       au_cpup_attr_timesizes(dir);
+                       drop_nlink(dir);
+               }
+               return 0; /* success */
+       }
+
+       AuWarn("failed removing %.*s(%d), ignored\n",
+              AuDLNPair(wh_dentry), err);
+       return err;
+}
+
+static void call_rmdir_whtmp(void *args)
+{
+       int err;
+       struct au_whtmp_rmdir *a = args;
+       struct super_block *sb;
+       struct dentry *h_parent;
+       struct inode *h_dir;
+       struct au_branch *br;
+       struct au_hinode *hdir;
+
+       /* rmdir by nfsd may cause deadlock with this i_mutex */
+       /* mutex_lock(&a->dir->i_mutex); */
+       sb = a->dir->i_sb;
+       si_noflush_read_lock(sb);
+       err = au_test_ro(sb, a->bindex, NULL);
+       if (unlikely(err))
+               goto out;
+
+       err = -EIO;
+       br = au_sbr(sb, a->bindex);
+       ii_write_lock_parent(a->dir);
+       h_parent = dget_parent(a->wh_dentry);
+       h_dir = h_parent->d_inode;
+       hdir = au_hi(a->dir, a->bindex);
+       au_hin_imtx_lock_nested(hdir, AuLsc_I_PARENT);
+       err = au_h_verify(a->wh_dentry, au_opt_udba(sb), h_dir, h_parent, br);
+       if (!err) {
+               err = mnt_want_write(br->br_mnt);
+               if (!err) {
+                       err = au_whtmp_rmdir(a->dir, a->bindex, a->wh_dentry,
+                                            a->whlist);
+                       mnt_drop_write(br->br_mnt);
+               }
+       }
+       au_hin_imtx_unlock(hdir);
+       dput(h_parent);
+       ii_write_unlock(a->dir);
+
+ out:
+       /* mutex_unlock(&a->dir->i_mutex); */
+       au_nwt_done(&au_sbi(sb)->si_nowait);
+       si_read_unlock(sb);
+       au_whtmp_rmdir_free(a);
+       if (unlikely(err))
+               AuIOErr("err %d\n", err);
+}
+
+void au_whtmp_kick_rmdir(struct inode *dir, aufs_bindex_t bindex,
+                        struct dentry *wh_dentry, struct au_whtmp_rmdir *args)
+{
+       int wkq_err;
+
+       IMustLock(dir);
+
+       /* all post-process will be done in do_rmdir_whtmp(). */
+       args->dir = au_igrab(dir);
+       args->bindex = bindex;
+       args->wh_dentry = dget(wh_dentry);
+       wkq_err = au_wkq_nowait(call_rmdir_whtmp, args, dir->i_sb);
+       if (unlikely(wkq_err)) {
+               AuWarn("rmdir error %.*s (%d), ignored\n",
+                      AuDLNPair(wh_dentry), wkq_err);
+               au_whtmp_rmdir_free(args);
+       }
+}
diff --git a/fs/aufs/whout.h b/fs/aufs/whout.h
new file mode 100644
index 0000000..3247a4f
--- /dev/null
+++ b/fs/aufs/whout.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * whiteout for logical deletion and opaque directory
+ */
+
+#ifndef __AUFS_WHOUT_H__
+#define __AUFS_WHOUT_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/aufs_type.h>
+#include "dir.h"
+
+/* whout.c */
+int au_wh_name_alloc(struct qstr *wh, const struct qstr *name);
+struct au_branch;
+int au_wh_test(struct dentry *h_parent, struct qstr *wh_name,
+              struct au_branch *br, int try_sio);
+int au_diropq_test(struct dentry *h_dentry, struct au_branch *br);
+struct dentry *au_whtmp_lkup(struct dentry *h_parent, struct au_branch *br,
+                            struct qstr *prefix);
+int au_whtmp_ren(struct dentry *h_dentry, struct au_branch *br);
+int au_wh_unlink_dentry(struct inode *h_dir, struct path *h_path,
+                       struct dentry *dentry);
+int au_wh_init(struct dentry *h_parent, struct au_branch *br,
+              struct super_block *sb);
+
+/* diropq flags */
+#define AuDiropq_CREATE        1
+#define au_ftest_diropq(flags, name)   ((flags) & AuDiropq_##name)
+#define au_fset_diropq(flags, name)    { (flags) |= AuDiropq_##name; }
+#define au_fclr_diropq(flags, name)    { (flags) &= ~AuDiropq_##name; }
+
+struct dentry *au_diropq_sio(struct dentry *dentry, aufs_bindex_t bindex,
+                            unsigned int flags);
+struct dentry *au_wh_lkup(struct dentry *h_parent, struct qstr *base_name,
+                         struct au_branch *br);
+struct dentry *au_wh_create(struct dentry *dentry, aufs_bindex_t bindex,
+                           struct dentry *h_parent);
+
+/* real rmdir for the whiteout-ed dir */
+struct au_whtmp_rmdir {
+       struct inode *dir;
+       aufs_bindex_t bindex;
+       struct dentry *wh_dentry;
+       struct au_nhash *whlist;
+};
+
+struct au_whtmp_rmdir *au_whtmp_rmdir_alloc(struct super_block *sb, gfp_t gfp);
+void au_whtmp_rmdir_free(struct au_whtmp_rmdir *whtmp);
+int au_whtmp_rmdir(struct inode *dir, aufs_bindex_t bindex,
+                  struct dentry *wh_dentry, struct au_nhash *whlist);
+void au_whtmp_kick_rmdir(struct inode *dir, aufs_bindex_t bindex,
+                        struct dentry *wh_dentry, struct au_whtmp_rmdir *args);
+
+/* ---------------------------------------------------------------------- */
+
+static inline struct dentry *au_diropq_create(struct dentry *dentry,
+                                             aufs_bindex_t bindex)
+{
+       return au_diropq_sio(dentry, bindex, AuDiropq_CREATE);
+}
+
+static inline int au_diropq_remove(struct dentry *dentry, aufs_bindex_t bindex)
+{
+       return PTR_ERR(au_diropq_sio(dentry, bindex, !AuDiropq_CREATE));
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_WHOUT_H__ */
diff --git a/fs/aufs/wkq.c b/fs/aufs/wkq.c
new file mode 100644
index 0000000..41e30be
--- /dev/null
+++ b/fs/aufs/wkq.c
@@ -0,0 +1,249 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * workqueue for asynchronous/super-io operations
+ * todo: try new dredential scheme
+ */
+
+#include "aufs.h"
+
+/* internal workqueue named AUFS_WKQ_NAME */
+static struct au_wkq {
+       struct workqueue_struct *q;
+
+       /* balancing */
+       atomic_t                busy;
+} *au_wkq;
+
+struct au_wkinfo {
+       struct work_struct wk;
+       struct super_block *sb;
+
+       unsigned int flags; /* see wkq.h */
+
+       au_wkq_func_t func;
+       void *args;
+
+       atomic_t *busyp;
+       struct completion *comp;
+};
+
+/* ---------------------------------------------------------------------- */
+
+static int enqueue(struct au_wkq *wkq, struct au_wkinfo *wkinfo)
+{
+       wkinfo->busyp = &wkq->busy;
+       if (au_ftest_wkq(wkinfo->flags, WAIT))
+               return !queue_work(wkq->q, &wkinfo->wk);
+       else
+               return !schedule_work(&wkinfo->wk);
+}
+
+static void do_wkq(struct au_wkinfo *wkinfo)
+{
+       unsigned int idle, n;
+       int i, idle_idx;
+
+       while (1) {
+               if (au_ftest_wkq(wkinfo->flags, WAIT)) {
+                       idle_idx = 0;
+                       idle = UINT_MAX;
+                       for (i = 0; i < aufs_nwkq; i++) {
+                               n = atomic_inc_return(&au_wkq[i].busy);
+                               if (n == 1 && !enqueue(au_wkq + i, wkinfo))
+                                       return; /* success */
+
+                               if (n < idle) {
+                                       idle_idx = i;
+                                       idle = n;
+                               }
+                               atomic_dec(&au_wkq[i].busy);
+                       }
+               } else
+                       idle_idx = aufs_nwkq;
+
+               atomic_inc(&au_wkq[idle_idx].busy);
+               if (!enqueue(au_wkq + idle_idx, wkinfo))
+                       return; /* success */
+
+               /* impossible? */
+               AuWarn1("failed to queue_work()\n");
+               yield();
+       }
+}
+
+static void wkq_func(struct work_struct *wk)
+{
+       struct au_wkinfo *wkinfo = container_of(wk, struct au_wkinfo, wk);
+
+       wkinfo->func(wkinfo->args);
+       atomic_dec(wkinfo->busyp);
+       if (au_ftest_wkq(wkinfo->flags, WAIT))
+               complete(wkinfo->comp);
+       else {
+               kobject_put(&au_sbi(wkinfo->sb)->si_kobj);
+               module_put(THIS_MODULE);
+               kfree(wkinfo);
+       }
+}
+
+/*
+ * Since struct completion is large, try allocating it dynamically.
+ */
+#if defined(CONFIG_4KSTACKS) || defined(AuTest4KSTACKS)
+#define AuWkqCompDeclare(name) struct completion *comp = NULL
+
+static int au_wkq_comp_alloc(struct au_wkinfo *wkinfo, struct completion **comp)
+{
+       *comp = kmalloc(sizeof(**comp), GFP_NOFS);
+       if (*comp) {
+               init_completion(*comp);
+               wkinfo->comp = *comp;
+               return 0;
+       }
+       return -ENOMEM;
+}
+
+static void au_wkq_comp_free(struct completion *comp)
+{
+       kfree(comp);
+}
+
+#else
+
+/* no braces */
+#define AuWkqCompDeclare(name) \
+       DECLARE_COMPLETION_ONSTACK(_ ## name); \
+       struct completion *comp = &_ ## name
+
+static int au_wkq_comp_alloc(struct au_wkinfo *wkinfo, struct completion **comp)
+{
+       wkinfo->comp = *comp;
+       return 0;
+}
+
+static void au_wkq_comp_free(struct completion *comp __maybe_unused)
+{
+       /* empty */
+}
+#endif /* 4KSTACKS */
+
+static void au_wkq_run(struct au_wkinfo *wkinfo)
+{
+       au_dbg_verify_kthread();
+       INIT_WORK(&wkinfo->wk, wkq_func);
+       do_wkq(wkinfo);
+}
+
+int au_wkq_wait(au_wkq_func_t func, void *args)
+{
+       int err;
+       AuWkqCompDeclare(comp);
+       struct au_wkinfo wkinfo = {
+               .flags  = AuWkq_WAIT,
+               .func   = func,
+               .args   = args
+       };
+
+       err = au_wkq_comp_alloc(&wkinfo, &comp);
+       if (!err) {
+               au_wkq_run(&wkinfo);
+               /* no timeout, no interrupt */
+               wait_for_completion(wkinfo.comp);
+               au_wkq_comp_free(comp);
+       }
+
+       return err;
+
+}
+
+int au_wkq_nowait(au_wkq_func_t func, void *args, struct super_block *sb)
+{
+       int err;
+       struct au_wkinfo *wkinfo;
+
+       atomic_inc(&au_sbi(sb)->si_nowait.nw_len);
+
+       /*
+        * wkq_func() must free this wkinfo.
+        * it highly depends upon the implementation of workqueue.
+        */
+       err = 0;
+       wkinfo = kmalloc(sizeof(*wkinfo), GFP_NOFS);
+       if (wkinfo) {
+               wkinfo->sb = sb;
+               wkinfo->flags = !AuWkq_WAIT;
+               wkinfo->func = func;
+               wkinfo->args = args;
+               wkinfo->comp = NULL;
+               kobject_get(&au_sbi(sb)->si_kobj);
+               __module_get(THIS_MODULE);
+
+               au_wkq_run(wkinfo);
+       } else {
+               err = -ENOMEM;
+               atomic_dec(&au_sbi(sb)->si_nowait.nw_len);
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_nwt_init(struct au_nowait_tasks *nwt)
+{
+       atomic_set(&nwt->nw_len, 0);
+       /* smp_mb();*/ /* atomic_set */
+       init_waitqueue_head(&nwt->nw_wq);
+}
+
+void au_wkq_fin(void)
+{
+       int i;
+
+       for (i = 0; i < aufs_nwkq; i++)
+               if (au_wkq[i].q && !IS_ERR(au_wkq[i].q))
+                       destroy_workqueue(au_wkq[i].q);
+       kfree(au_wkq);
+}
+
+int __init au_wkq_init(void)
+{
+       int err, i;
+       struct au_wkq *nowaitq;
+
+       /* '+1' is for accounting of nowait queue */
+       err = -ENOMEM;
+       au_wkq = kcalloc(aufs_nwkq + 1, sizeof(*au_wkq), GFP_NOFS);
+       if (unlikely(!au_wkq))
+               goto out;
+
+       err = 0;
+       for (i = 0; i < aufs_nwkq; i++) {
+               au_wkq[i].q = create_singlethread_workqueue(AUFS_WKQ_NAME);
+               if (au_wkq[i].q && !IS_ERR(au_wkq[i].q)) {
+                       atomic_set(&au_wkq[i].busy, 0);
+                       continue;
+               }
+
+               err = PTR_ERR(au_wkq[i].q);
+               au_wkq_fin();
+               goto out;
+       }
+
+       /* nowait accounting */
+       nowaitq = au_wkq + aufs_nwkq;
+       atomic_set(&nowaitq->busy, 0);
+       nowaitq->q = NULL;
+       /* smp_mb(); */ /* atomic_set */
+
+ out:
+       return err;
+}
diff --git a/fs/aufs/wkq.h b/fs/aufs/wkq.h
new file mode 100644
index 0000000..17d24d8
--- /dev/null
+++ b/fs/aufs/wkq.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * workqueue for asynchronous/super-io operations
+ * todo: try new credentials management scheme
+ */
+
+#ifndef __AUFS_WKQ_H__
+#define __AUFS_WKQ_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/workqueue.h>
+#include <linux/aufs_type.h>
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * in the next operation, wait for the 'nowait' tasks in system-wide workqueue
+ */
+struct au_nowait_tasks {
+       atomic_t                nw_len;
+       wait_queue_head_t       nw_wq;
+};
+
+/* ---------------------------------------------------------------------- */
+
+typedef void (*au_wkq_func_t)(void *args);
+
+/* wkq flags */
+#define AuWkq_WAIT     1
+#define au_ftest_wkq(flags, name)      ((flags) & AuWkq_##name)
+#define au_fset_wkq(flags, name)       { (flags) |= AuWkq_##name; }
+#define au_fclr_wkq(flags, name)       { (flags) &= ~AuWkq_##name; }
+
+/* wkq.c */
+int au_wkq_wait(au_wkq_func_t func, void *args);
+int au_wkq_nowait(au_wkq_func_t func, void *args, struct super_block *sb);
+void au_nwt_init(struct au_nowait_tasks *nwt);
+int __init au_wkq_init(void);
+void au_wkq_fin(void);
+
+/* ---------------------------------------------------------------------- */
+
+static inline int au_test_wkq(struct task_struct *tsk)
+{
+       return !tsk->mm && !strcmp(tsk->comm, AUFS_WKQ_NAME);
+}
+
+static inline void au_nwt_done(struct au_nowait_tasks *nwt)
+{
+       if (!atomic_dec_return(&nwt->nw_len))
+               wake_up_all(&nwt->nw_wq);
+}
+
+static inline int au_nwt_flush(struct au_nowait_tasks *nwt)
+{
+       wait_event(nwt->nw_wq, !atomic_read(&nwt->nw_len));
+       return 0;
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_WKQ_H__ */
diff --git a/fs/aufs/xino.c b/fs/aufs/xino.c
new file mode 100644
index 0000000..7d11111
--- /dev/null
+++ b/fs/aufs/xino.c
@@ -0,0 +1,1181 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * external inode number translation table and bitmap
+ */
+
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include "aufs.h"
+
+ssize_t xino_fread(au_readf_t func, struct file *file, void *buf, size_t size,
+                  loff_t *pos)
+{
+       ssize_t err;
+       mm_segment_t oldfs;
+
+       oldfs = get_fs();
+       set_fs(KERNEL_DS);
+       do {
+               /* todo: signal_pending? */
+               err = func(file, (char __user *)buf, size, pos);
+       } while (err == -EAGAIN || err == -EINTR);
+       set_fs(oldfs);
+
+#if 0 /* reserved for future use */
+       if (err > 0)
+               fsnotify_access(file->f_dentry);
+#endif
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static ssize_t do_xino_fwrite(au_writef_t func, struct file *file, void *buf,
+                             size_t size, loff_t *pos)
+{
+       ssize_t err;
+       mm_segment_t oldfs;
+
+       oldfs = get_fs();
+       set_fs(KERNEL_DS);
+       lockdep_off();
+       do {
+               /* todo: signal_pending? */
+               err = func(file, (const char __user *)buf, size, pos);
+       } while (err == -EAGAIN || err == -EINTR);
+       lockdep_on();
+       set_fs(oldfs);
+
+#if 0 /* reserved for future use */
+       if (err > 0)
+               fsnotify_modify(file->f_dentry);
+#endif
+
+       return err;
+}
+
+struct do_xino_fwrite_args {
+       ssize_t *errp;
+       au_writef_t func;
+       struct file *file;
+       void *buf;
+       size_t size;
+       loff_t *pos;
+};
+
+static void call_do_xino_fwrite(void *args)
+{
+       struct do_xino_fwrite_args *a = args;
+       *a->errp = do_xino_fwrite(a->func, a->file, a->buf, a->size, a->pos);
+}
+
+ssize_t xino_fwrite(au_writef_t func, struct file *file, void *buf, size_t size,
+                   loff_t *pos)
+{
+       ssize_t err;
+
+       /* todo: signal block and no wkq? */
+       /* todo: new credential scheme */
+       /*
+        * it breaks RLIMIT_FSIZE and normal user's limit,
+        * users should care about quota and real 'filesystem full.'
+        */
+       if (!au_test_wkq(current)) {
+               int wkq_err;
+               struct do_xino_fwrite_args args = {
+                       .errp   = &err,
+                       .func   = func,
+                       .file   = file,
+                       .buf    = buf,
+                       .size   = size,
+                       .pos    = pos
+               };
+
+               wkq_err = au_wkq_wait(call_do_xino_fwrite, &args);
+               if (unlikely(wkq_err))
+                       err = wkq_err;
+       } else
+               err = do_xino_fwrite(func, file, buf, size, pos);
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * create a new xinofile at the same place/path as @base_file.
+ */
+struct file *au_xino_create2(struct file *base_file, struct file *copy_src)
+{
+       struct file *file;
+       struct dentry *base, *dentry, *parent;
+       struct inode *dir;
+       struct qstr *name;
+       int err;
+
+       base = base_file->f_dentry;
+       parent = base->d_parent; /* dir inode is locked */
+       dir = parent->d_inode;
+       IMustLock(dir);
+
+       file = ERR_PTR(-EINVAL);
+       name = &base->d_name;
+       dentry = vfsub_lookup_one_len(name->name, parent, name->len);
+       if (IS_ERR(dentry)) {
+               file = (void *)dentry;
+               AuErr("%.*s lookup err %ld\n", AuLNPair(name), PTR_ERR(dentry));
+               goto out;
+       }
+
+       /* no need to mnt_want_write() since we call dentry_open() later */
+       err = vfs_create(dir, dentry, S_IRUGO | S_IWUGO, NULL);
+       if (unlikely(err)) {
+               file = ERR_PTR(err);
+               AuErr("%.*s create err %d\n", AuLNPair(name), err);
+               goto out_dput;
+       }
+
+       file = dentry_open(dget(dentry), mntget(base_file->f_vfsmnt),
+                          O_RDWR | O_CREAT | O_EXCL | O_LARGEFILE,
+                          current_cred());
+       if (IS_ERR(file)) {
+               AuErr("%.*s open err %ld\n", AuLNPair(name), PTR_ERR(file));
+               goto out_dput;
+       }
+
+       err = vfsub_unlink(dir, &file->f_path, /*force*/0);
+       if (unlikely(err)) {
+               AuErr("%.*s unlink err %d\n", AuLNPair(name), err);
+               goto out_fput;
+       }
+
+       if (copy_src) {
+               /* no one can touch copy_src xino */
+               err = au_copy_file(file, copy_src,
+                                  i_size_read(copy_src->f_dentry->d_inode));
+               if (unlikely(err)) {
+                       AuErr("%.*s copy err %d\n", AuLNPair(name), err);
+                       goto out_fput;
+               }
+       }
+       goto out_dput; /* success */
+
+ out_fput:
+       fput(file);
+       file = ERR_PTR(err);
+ out_dput:
+       dput(dentry);
+ out:
+       return file;
+}
+
+struct au_xino_lock_dir {
+       struct au_hinode *hdir;
+       struct dentry *parent;
+       struct mutex *mtx;
+};
+
+static void au_xino_lock_dir(struct super_block *sb, struct file *xino,
+                            struct au_xino_lock_dir *ldir)
+{
+       aufs_bindex_t brid, bindex;
+
+       ldir->hdir = NULL;
+       bindex = -1;
+       brid = au_xino_brid(sb);
+       if (brid >= 0)
+               bindex = au_br_index(sb, brid);
+       if (bindex >= 0) {
+               ldir->hdir = au_hi(sb->s_root->d_inode, bindex);
+               au_hin_imtx_lock_nested(ldir->hdir, AuLsc_I_PARENT);
+       } else {
+               ldir->parent = dget_parent(xino->f_dentry);
+               ldir->mtx = &ldir->parent->d_inode->i_mutex;
+               mutex_lock_nested(ldir->mtx, AuLsc_I_PARENT);
+       }
+}
+
+static void au_xino_unlock_dir(struct au_xino_lock_dir *ldir)
+{
+       if (ldir->hdir)
+               au_hin_imtx_unlock(ldir->hdir);
+       else {
+               mutex_unlock(ldir->mtx);
+               dput(ldir->parent);
+       }
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* trucate xino files asynchronously */
+
+int au_xino_trunc(struct super_block *sb, aufs_bindex_t bindex)
+{
+       int err;
+       aufs_bindex_t bi, bend;
+       struct au_branch *br;
+       struct file *new_xino, *file;
+       struct super_block *h_sb;
+       struct au_xino_lock_dir ldir;
+
+       err = -EINVAL;
+       bend = au_sbend(sb);
+       if (unlikely(bindex < 0 || bend < bindex))
+               goto out;
+       br = au_sbr(sb, bindex);
+       file = br->br_xino.xi_file;
+       if (!file)
+               goto out;
+
+       au_xino_lock_dir(sb, file, &ldir);
+       /* mnt_want_write() is unnecessary here */
+       new_xino = au_xino_create2(file, file);
+       au_xino_unlock_dir(&ldir);
+       err = PTR_ERR(new_xino);
+       if (IS_ERR(new_xino))
+               goto out;
+       err = 0;
+       fput(file);
+       br->br_xino.xi_file = new_xino;
+
+       h_sb = br->br_mnt->mnt_sb;
+       for (bi = 0; bi <= bend; bi++) {
+               if (unlikely(bi == bindex))
+                       continue;
+               br = au_sbr(sb, bi);
+               if (br->br_mnt->mnt_sb != h_sb)
+                       continue;
+
+               fput(br->br_xino.xi_file);
+               br->br_xino.xi_file = new_xino;
+               get_file(new_xino);
+       }
+
+ out:
+       return err;
+}
+
+struct xino_do_trunc_args {
+       struct super_block *sb;
+       struct au_branch *br;
+};
+
+static void xino_do_trunc(void *_args)
+{
+       struct xino_do_trunc_args *args = _args;
+       struct super_block *sb;
+       struct au_branch *br;
+       struct inode *dir;
+       int err;
+       aufs_bindex_t bindex;
+
+       err = 0;
+       sb = args->sb;
+       dir = sb->s_root->d_inode;
+       br = args->br;
+
+       si_noflush_write_lock(sb);
+       ii_read_lock_parent(dir);
+       bindex = au_br_index(sb, br->br_id);
+       err = au_xino_trunc(sb, bindex);
+       if (unlikely(err))
+               goto out;
+
+       if (br->br_xino.xi_file->f_dentry->d_inode->i_blocks
+           >= br->br_xino_upper)
+               br->br_xino_upper += AUFS_XINO_TRUNC_STEP;
+
+ out:
+       ii_read_unlock(dir);
+       if (unlikely(err))
+               AuWarn("err b%d, (%d)\n", bindex, err);
+       atomic_dec(&br->br_xino_running);
+       atomic_dec(&br->br_count);
+       au_nwt_done(&au_sbi(sb)->si_nowait);
+       si_write_unlock(sb);
+       kfree(args);
+}
+
+static void xino_try_trunc(struct super_block *sb, struct au_branch *br)
+{
+       struct xino_do_trunc_args *args;
+       int wkq_err;
+
+       if (br->br_xino.xi_file->f_dentry->d_inode->i_blocks
+           < br->br_xino_upper)
+               return;
+
+       if (atomic_inc_return(&br->br_xino_running) > 1)
+               goto out;
+
+       /* lock and kfree() will be called in trunc_xino() */
+       args = kmalloc(sizeof(*args), GFP_NOFS);
+       if (unlikely(!args)) {
+               AuErr1("no memory\n");
+               goto out_args;
+       }
+
+       atomic_inc(&br->br_count);
+       args->sb = sb;
+       args->br = br;
+       wkq_err = au_wkq_nowait(xino_do_trunc, args, sb);
+       if (!wkq_err)
+               return; /* success */
+
+       AuErr("wkq %d\n", wkq_err);
+       atomic_dec(&br->br_count);
+
+ out_args:
+       kfree(args);
+ out:
+       atomic_dec(&br->br_xino_running);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_xino_do_write(au_writef_t write, struct file *file,
+                           ino_t h_ino, ino_t ino)
+{
+       loff_t pos;
+       ssize_t sz;
+
+       pos = h_ino;
+       if (unlikely(au_loff_max / sizeof(ino) - 1 < pos)) {
+               AuIOErr1("too large hi%lu\n", (unsigned long)h_ino);
+               return -EFBIG;
+       }
+       pos *= sizeof(ino);
+       sz = xino_fwrite(write, file, &ino, sizeof(ino), &pos);
+       if (sz == sizeof(ino))
+               return 0; /* success */
+
+       AuIOErr("write failed (%zd)\n", sz);
+       return -EIO;
+}
+
+/*
+ * write @ino to the xinofile for the specified branch{@sb, @bindex}
+ * at the position of @h_ino.
+ * even if @ino is zero, it is written to the xinofile and means no entry.
+ * if the size of the xino file on a specific filesystem exceeds the watermark,
+ * try truncating it.
+ */
+int au_xino_write(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                 ino_t ino)
+{
+       int err;
+       unsigned int mnt_flags;
+       struct au_branch *br;
+
+       BUILD_BUG_ON(sizeof(long long) != sizeof(au_loff_max)
+                    || ((loff_t)-1) > 0);
+
+       mnt_flags = au_mntflags(sb);
+       if (!au_opt_test(mnt_flags, XINO))
+               return 0;
+
+       br = au_sbr(sb, bindex);
+       err = au_xino_do_write(au_sbi(sb)->si_xwrite, br->br_xino.xi_file,
+                              h_ino, ino);
+       if (!err) {
+               if (au_opt_test(mnt_flags, TRUNC_XINO)
+                   && au_test_fs_trunc_xino(br->br_mnt->mnt_sb))
+                       xino_try_trunc(sb, br);
+               return 0; /* success */
+       }
+
+       AuIOErr("write failed (%d)\n", err);
+       return -EIO;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* aufs inode number bitmap */
+
+static const int page_bits = (int)PAGE_SIZE * BITS_PER_BYTE;
+static ino_t xib_calc_ino(unsigned long pindex, int bit)
+{
+       ino_t ino;
+
+       AuDebugOn(bit < 0 || page_bits <= bit);
+       ino = AUFS_FIRST_INO + pindex * page_bits + bit;
+       return ino;
+}
+
+static void xib_calc_bit(ino_t ino, unsigned long *pindex, int *bit)
+{
+       AuDebugOn(ino < AUFS_FIRST_INO);
+       ino -= AUFS_FIRST_INO;
+       *pindex = ino / page_bits;
+       *bit = ino % page_bits;
+}
+
+static int xib_pindex(struct super_block *sb, unsigned long pindex)
+{
+       int err;
+       loff_t pos;
+       ssize_t sz;
+       struct au_sbinfo *sbinfo;
+       struct file *xib;
+       unsigned long *p;
+
+       sbinfo = au_sbi(sb);
+       MtxMustLock(&sbinfo->si_xib_mtx);
+       AuDebugOn(pindex > ULONG_MAX / PAGE_SIZE
+                 || !au_opt_test(sbinfo->si_mntflags, XINO));
+
+       if (pindex == sbinfo->si_xib_last_pindex)
+               return 0;
+
+       xib = sbinfo->si_xib;
+       p = sbinfo->si_xib_buf;
+       pos = sbinfo->si_xib_last_pindex;
+       pos *= PAGE_SIZE;
+       sz = xino_fwrite(sbinfo->si_xwrite, xib, p, PAGE_SIZE, &pos);
+       if (unlikely(sz != PAGE_SIZE))
+               goto out;
+
+       pos = pindex;
+       pos *= PAGE_SIZE;
+       if (i_size_read(xib->f_dentry->d_inode) >= pos + PAGE_SIZE)
+               sz = xino_fread(sbinfo->si_xread, xib, p, PAGE_SIZE, &pos);
+       else {
+               memset(p, 0, PAGE_SIZE);
+               sz = xino_fwrite(sbinfo->si_xwrite, xib, p, PAGE_SIZE, &pos);
+       }
+       if (sz == PAGE_SIZE) {
+               sbinfo->si_xib_last_pindex = pindex;
+               return 0; /* success */
+       }
+
+ out:
+       AuIOErr1("write failed (%zd)\n", sz);
+       err = sz;
+       if (sz >= 0)
+               err = -EIO;
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_xino_write0(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                  ino_t ino)
+{
+       int err, bit;
+       unsigned long pindex;
+       struct au_sbinfo *sbinfo;
+
+       if (!au_opt_test(au_mntflags(sb), XINO))
+               return 0;
+
+       err = 0;
+       if (ino) {
+               sbinfo = au_sbi(sb);
+               xib_calc_bit(ino, &pindex, &bit);
+               AuDebugOn(page_bits <= bit);
+               mutex_lock(&sbinfo->si_xib_mtx);
+               err = xib_pindex(sb, pindex);
+               if (!err) {
+                       clear_bit(bit, sbinfo->si_xib_buf);
+                       sbinfo->si_xib_next_bit = bit;
+               }
+               mutex_unlock(&sbinfo->si_xib_mtx);
+       }
+
+       if (!err)
+               err = au_xino_write(sb, bindex, h_ino, 0);
+       return err;
+}
+
+/* get an unused inode number from bitmap */
+ino_t au_xino_new_ino(struct super_block *sb)
+{
+       ino_t ino;
+       unsigned long *p, pindex, ul, pend;
+       struct au_sbinfo *sbinfo;
+       struct file *file;
+       int free_bit, err;
+
+       if (!au_opt_test(au_mntflags(sb), XINO))
+               return iunique(sb, AUFS_FIRST_INO);
+
+       sbinfo = au_sbi(sb);
+       mutex_lock(&sbinfo->si_xib_mtx);
+       p = sbinfo->si_xib_buf;
+       free_bit = sbinfo->si_xib_next_bit;
+       if (free_bit < page_bits && !test_bit(free_bit, p))
+               goto out; /* success */
+       free_bit = find_first_zero_bit(p, page_bits);
+       if (free_bit < page_bits)
+               goto out; /* success */
+
+       pindex = sbinfo->si_xib_last_pindex;
+       for (ul = pindex - 1; ul < ULONG_MAX; ul--) {
+               err = xib_pindex(sb, ul);
+               if (unlikely(err))
+                       goto out_err;
+               free_bit = find_first_zero_bit(p, page_bits);
+               if (free_bit < page_bits)
+                       goto out; /* success */
+       }
+
+       file = sbinfo->si_xib;
+       pend = i_size_read(file->f_dentry->d_inode) / PAGE_SIZE;
+       for (ul = pindex + 1; ul <= pend; ul++) {
+               err = xib_pindex(sb, ul);
+               if (unlikely(err))
+                       goto out_err;
+               free_bit = find_first_zero_bit(p, page_bits);
+               if (free_bit < page_bits)
+                       goto out; /* success */
+       }
+       BUG();
+
+ out:
+       set_bit(free_bit, p);
+       sbinfo->si_xib_next_bit++;
+       pindex = sbinfo->si_xib_last_pindex;
+       mutex_unlock(&sbinfo->si_xib_mtx);
+       ino = xib_calc_ino(pindex, free_bit);
+       AuDbg("i%lu\n", (unsigned long)ino);
+       return ino;
+ out_err:
+       mutex_unlock(&sbinfo->si_xib_mtx);
+       AuDbg("i0\n");
+       return 0;
+}
+
+/*
+ * read @ino from xinofile for the specified branch{@sb, @bindex}
+ * at the position of @h_ino.
+ * if @ino does not exist and @do_new is true, get new one.
+ */
+int au_xino_read(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+                ino_t *ino)
+{
+       int err;
+       ssize_t sz;
+       loff_t pos;
+       struct file *file;
+       struct au_sbinfo *sbinfo;
+
+       *ino = 0;
+       if (!au_opt_test(au_mntflags(sb), XINO))
+               return 0; /* no xino */
+
+       err = 0;
+       sbinfo = au_sbi(sb);
+       pos = h_ino;
+       if (unlikely(au_loff_max / sizeof(*ino) - 1 < pos)) {
+               AuIOErr1("too large hi%lu\n", (unsigned long)h_ino);
+               return -EFBIG;
+       }
+       pos *= sizeof(*ino);
+
+       file = au_sbr(sb, bindex)->br_xino.xi_file;
+       if (i_size_read(file->f_dentry->d_inode) < pos + sizeof(*ino))
+               return 0; /* no ino */
+
+       sz = xino_fread(sbinfo->si_xread, file, ino, sizeof(*ino), &pos);
+       if (sz == sizeof(*ino))
+               return 0; /* success */
+
+       err = sz;
+       if (unlikely(sz >= 0)) {
+               err = -EIO;
+               AuIOErr("xino read error (%zd)\n", sz);
+       }
+
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* create and set a new xino file */
+
+struct file *au_xino_create(struct super_block *sb, char *fname, int silent)
+{
+       struct file *file;
+       struct dentry *h_parent, *d;
+       struct inode *h_dir;
+       int err;
+
+       /*
+        * at mount-time, and the xino file is the default path,
+        * hinotify is disabled so we have no inotify events to ignore.
+        * when a user specified the xino, we cannot get au_hdir to be ignored.
+        */
+       file = vfsub_filp_open(fname, O_RDWR | O_CREAT | O_EXCL | O_LARGEFILE,
+                              S_IRUGO | S_IWUGO);
+       if (IS_ERR(file)) {
+               if (!silent)
+                       AuErr("open %s(%ld)\n", fname, PTR_ERR(file));
+               return file;
+       }
+
+       /* keep file count */
+       h_parent = dget_parent(file->f_dentry);
+       h_dir = h_parent->d_inode;
+       mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_PARENT);
+       /* mnt_want_write() is unnecessary here */
+       err = vfsub_unlink(h_dir, &file->f_path, /*force*/0);
+       mutex_unlock(&h_dir->i_mutex);
+       dput(h_parent);
+       if (unlikely(err)) {
+               if (!silent)
+                       AuErr("unlink %s(%d)\n", fname, err);
+               goto out;
+       }
+
+       err = -EINVAL;
+       d = file->f_dentry;
+       if (unlikely(sb == d->d_sb)) {
+               if (!silent)
+                       AuErr("%s must be outside\n", fname);
+               goto out;
+       }
+       if (unlikely(au_test_fs_bad_xino(d->d_sb))) {
+               if (!silent)
+                       AuErr("xino doesn't support %s(%s)\n",
+                             fname, au_sbtype(d->d_sb));
+               goto out;
+       }
+       return file; /* success */
+
+ out:
+       fput(file);
+       file = ERR_PTR(err);
+       return file;
+}
+
+/*
+ * find another branch who is on the same filesystem of the specified
+ * branch{@btgt}. search until @bend.
+ */
+static int is_sb_shared(struct super_block *sb, aufs_bindex_t btgt,
+                       aufs_bindex_t bend)
+{
+       aufs_bindex_t bindex;
+       struct super_block *tgt_sb = au_sbr_sb(sb, btgt);
+
+       for (bindex = 0; bindex < btgt; bindex++)
+               if (unlikely(tgt_sb == au_sbr_sb(sb, bindex)))
+                       return bindex;
+       for (bindex++; bindex <= bend; bindex++)
+               if (unlikely(tgt_sb == au_sbr_sb(sb, bindex)))
+                       return bindex;
+       return -1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * initialize the xinofile for the specified branch @br
+ * at the place/path where @base_file indicates.
+ * test whether another branch is on the same filesystem or not,
+ * if @do_test is true.
+ */
+int au_xino_br(struct super_block *sb, struct au_branch *br, ino_t h_ino,
+              struct file *base_file, int do_test)
+{
+       int err;
+       ino_t ino;
+       aufs_bindex_t bend, bindex;
+       struct au_branch *shared_br, *b;
+       struct file *file;
+       struct super_block *tgt_sb;
+
+       shared_br = NULL;
+       bend = au_sbend(sb);
+       if (do_test) {
+               tgt_sb = br->br_mnt->mnt_sb;
+               for (bindex = 0; bindex <= bend; bindex++) {
+                       b = au_sbr(sb, bindex);
+                       if (tgt_sb == b->br_mnt->mnt_sb) {
+                               shared_br = b;
+                               break;
+                       }
+               }
+       }
+
+       if (!shared_br || !shared_br->br_xino.xi_file) {
+               struct au_xino_lock_dir ldir;
+
+               au_xino_lock_dir(sb, base_file, &ldir);
+               /* mnt_want_write() is unnecessary here */
+               file = au_xino_create2(base_file, NULL);
+               au_xino_unlock_dir(&ldir);
+               err = PTR_ERR(file);
+               if (IS_ERR(file))
+                       goto out;
+               br->br_xino.xi_file = file;
+       } else {
+               br->br_xino.xi_file = shared_br->br_xino.xi_file;
+               get_file(br->br_xino.xi_file);
+       }
+
+       ino = AUFS_ROOT_INO;
+       err = au_xino_do_write(au_sbi(sb)->si_xwrite, br->br_xino.xi_file,
+                              h_ino, ino);
+       if (!err)
+               return 0; /* success */
+
+
+ out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* trucate a xino bitmap file */
+
+/* todo: slow */
+static int do_xib_restore(struct super_block *sb, struct file *file, void *page)
+{
+       int err, bit;
+       ssize_t sz;
+       unsigned long pindex;
+       loff_t pos, pend;
+       struct au_sbinfo *sbinfo;
+       au_readf_t func;
+       ino_t *ino;
+       unsigned long *p;
+
+       err = 0;
+       sbinfo = au_sbi(sb);
+       p = sbinfo->si_xib_buf;
+       func = sbinfo->si_xread;
+       pend = i_size_read(file->f_dentry->d_inode);
+       pos = 0;
+       while (pos < pend) {
+               sz = xino_fread(func, file, page, PAGE_SIZE, &pos);
+               err = sz;
+               if (unlikely(sz <= 0))
+                       goto out;
+
+               err = 0;
+               for (ino = page; sz > 0; ino++, sz -= sizeof(ino)) {
+                       if (unlikely(*ino < AUFS_FIRST_INO))
+                               continue;
+
+                       xib_calc_bit(*ino, &pindex, &bit);
+                       AuDebugOn(page_bits <= bit);
+                       err = xib_pindex(sb, pindex);
+                       if (!err)
+                               set_bit(bit, p);
+                       else
+                               goto out;
+               }
+       }
+
+ out:
+       return err;
+}
+
+static int xib_restore(struct super_block *sb)
+{
+       int err;
+       aufs_bindex_t bindex, bend;
+       void *page;
+
+       err = -ENOMEM;
+       page = (void *)__get_free_page(GFP_NOFS);
+       if (unlikely(!page))
+               goto out;
+
+       err = 0;
+       bend = au_sbend(sb);
+       for (bindex = 0; !err && bindex <= bend; bindex++)
+               if (!bindex || is_sb_shared(sb, bindex, bindex - 1) < 0)
+                       err = do_xib_restore
+                               (sb, au_sbr(sb, bindex)->br_xino.xi_file, page);
+               else
+                       AuDbg("b%d\n", bindex);
+       free_page((unsigned long)page);
+
+ out:
+       return err;
+}
+
+int au_xib_trunc(struct super_block *sb)
+{
+       int err;
+       ssize_t sz;
+       loff_t pos;
+       struct au_xino_lock_dir ldir;
+       struct au_sbinfo *sbinfo;
+       unsigned long *p;
+       struct file *file;
+
+       err = 0;
+       sbinfo = au_sbi(sb);
+       if (!au_opt_test(sbinfo->si_mntflags, XINO))
+               goto out;
+
+       file = sbinfo->si_xib;
+       if (i_size_read(file->f_dentry->d_inode) <= PAGE_SIZE)
+               goto out;
+
+       au_xino_lock_dir(sb, file, &ldir);
+       /* mnt_want_write() is unnecessary here */
+       file = au_xino_create2(sbinfo->si_xib, NULL);
+       au_xino_unlock_dir(&ldir);
+       err = PTR_ERR(file);
+       if (IS_ERR(file))
+               goto out;
+       fput(sbinfo->si_xib);
+       sbinfo->si_xib = file;
+
+       p = sbinfo->si_xib_buf;
+       memset(p, 0, PAGE_SIZE);
+       pos = 0;
+       sz = xino_fwrite(sbinfo->si_xwrite, sbinfo->si_xib, p, PAGE_SIZE, &pos);
+       if (unlikely(sz != PAGE_SIZE)) {
+               err = sz;
+               AuIOErr("err %d\n", err);
+               if (sz >= 0)
+                       err = -EIO;
+               goto out;
+       }
+
+       mutex_lock(&sbinfo->si_xib_mtx);
+       /* mnt_want_write() is unnecessary here */
+       err = xib_restore(sb);
+       mutex_unlock(&sbinfo->si_xib_mtx);
+
+out:
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * xino mount option handlers
+ */
+static au_readf_t find_readf(struct file *h_file)
+{
+       const struct file_operations *fop = h_file->f_op;
+
+       if (fop) {
+               if (fop->read)
+                       return fop->read;
+               if (fop->aio_read)
+                       return do_sync_read;
+       }
+       return ERR_PTR(-ENOSYS);
+}
+
+static au_writef_t find_writef(struct file *h_file)
+{
+       const struct file_operations *fop = h_file->f_op;
+
+       if (fop) {
+               if (fop->write)
+                       return fop->write;
+               if (fop->aio_write)
+                       return do_sync_write;
+       }
+       return ERR_PTR(-ENOSYS);
+}
+
+/* xino bitmap */
+static void xino_clear_xib(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+
+       sbinfo = au_sbi(sb);
+       sbinfo->si_xread = NULL;
+       sbinfo->si_xwrite = NULL;
+       if (sbinfo->si_xib)
+               fput(sbinfo->si_xib);
+       sbinfo->si_xib = NULL;
+       free_page((unsigned long)sbinfo->si_xib_buf);
+       sbinfo->si_xib_buf = NULL;
+}
+
+static int au_xino_set_xib(struct super_block *sb, struct file *base)
+{
+       int err;
+       loff_t pos;
+       struct au_sbinfo *sbinfo;
+       struct file *file;
+
+       sbinfo = au_sbi(sb);
+       file = au_xino_create2(base, sbinfo->si_xib);
+       err = PTR_ERR(file);
+       if (IS_ERR(file))
+               goto out;
+       if (sbinfo->si_xib)
+               fput(sbinfo->si_xib);
+       sbinfo->si_xib = file;
+       sbinfo->si_xread = find_readf(file);
+       sbinfo->si_xwrite = find_writef(file);
+
+       err = -ENOMEM;
+       if (!sbinfo->si_xib_buf)
+               sbinfo->si_xib_buf = (void *)get_zeroed_page(GFP_NOFS);
+       if (unlikely(!sbinfo->si_xib_buf))
+               goto out_unset;
+
+       sbinfo->si_xib_last_pindex = 0;
+       sbinfo->si_xib_next_bit = 0;
+       if (i_size_read(file->f_dentry->d_inode) < PAGE_SIZE) {
+               pos = 0;
+               err = xino_fwrite(sbinfo->si_xwrite, file, sbinfo->si_xib_buf,
+                                 PAGE_SIZE, &pos);
+               if (unlikely(err != PAGE_SIZE))
+                       goto out_free;
+       }
+       err = 0;
+       goto out; /* success */
+
+ out_free:
+       free_page((unsigned long)sbinfo->si_xib_buf);
+       sbinfo->si_xib_buf = NULL;
+       if (err >= 0)
+               err = -EIO;
+ out_unset:
+       fput(sbinfo->si_xib);
+       sbinfo->si_xib = NULL;
+       sbinfo->si_xread = NULL;
+       sbinfo->si_xwrite = NULL;
+ out:
+       return err;
+}
+
+/* xino for each branch */
+static void xino_clear_br(struct super_block *sb)
+{
+       aufs_bindex_t bindex, bend;
+       struct au_branch *br;
+
+       bend = au_sbend(sb);
+       for (bindex = 0; bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               if (!br || !br->br_xino.xi_file)
+                       continue;
+
+               fput(br->br_xino.xi_file);
+               br->br_xino.xi_file = NULL;
+       }
+}
+
+static int au_xino_set_br(struct super_block *sb, struct file *base)
+{
+       int err;
+       ino_t ino;
+       aufs_bindex_t bindex, bend, bshared;
+       struct {
+               struct file *old, *new;
+       } *fpair, *p;
+       struct au_branch *br;
+       struct inode *inode;
+       au_writef_t writef;
+
+       err = -ENOMEM;
+       bend = au_sbend(sb);
+       fpair = kcalloc(bend + 1, sizeof(*fpair), GFP_NOFS);
+       if (unlikely(!fpair))
+               goto out;
+
+       inode = sb->s_root->d_inode;
+       ino = AUFS_ROOT_INO;
+       writef = au_sbi(sb)->si_xwrite;
+       for (bindex = 0, p = fpair; bindex <= bend; bindex++, p++) {
+               br = au_sbr(sb, bindex);
+               bshared = is_sb_shared(sb, bindex, bindex - 1);
+               if (bshared >= 0) {
+                       /* shared xino */
+                       *p = fpair[bshared];
+                       get_file(p->new);
+               }
+
+               if (!p->new) {
+                       /* new xino */
+                       p->old = br->br_xino.xi_file;
+                       p->new = au_xino_create2(base, br->br_xino.xi_file);
+                       err = PTR_ERR(p->new);
+                       if (IS_ERR(p->new)) {
+                               p->new = NULL;
+                               goto out_pair;
+                       }
+               }
+
+               err = au_xino_do_write(writef, p->new,
+                                      au_h_iptr(inode, bindex)->i_ino, ino);
+               if (unlikely(err))
+                       goto out_pair;
+       }
+
+       for (bindex = 0, p = fpair; bindex <= bend; bindex++, p++) {
+               br = au_sbr(sb, bindex);
+               if (br->br_xino.xi_file)
+                       fput(br->br_xino.xi_file);
+               get_file(p->new);
+               br->br_xino.xi_file = p->new;
+       }
+
+ out_pair:
+       for (bindex = 0, p = fpair; bindex <= bend; bindex++, p++)
+               if (p->new)
+                       fput(p->new);
+               else
+                       break;
+       kfree(fpair);
+ out:
+       return err;
+}
+
+void au_xino_clr(struct super_block *sb)
+{
+       struct au_sbinfo *sbinfo;
+
+       au_xigen_clr(sb);
+       xino_clear_xib(sb);
+       xino_clear_br(sb);
+       sbinfo = au_sbi(sb);
+       /* lvalue, do not call au_mntflags() */
+       au_opt_clr(sbinfo->si_mntflags, XINO);
+}
+
+int au_xino_set(struct super_block *sb, struct au_opt_xino *xino, int remount)
+{
+       int err, skip;
+       struct dentry *parent, *cur_parent;
+       struct qstr *dname, *cur_name;
+       struct file *cur_xino;
+       struct inode *dir;
+       struct au_sbinfo *sbinfo;
+
+       err = 0;
+       sbinfo = au_sbi(sb);
+       parent = dget_parent(xino->file->f_dentry);
+       if (remount) {
+               skip = 0;
+               dname = &xino->file->f_dentry->d_name;
+               cur_xino = sbinfo->si_xib;
+               if (cur_xino) {
+                       cur_parent = dget_parent(cur_xino->f_dentry);
+                       cur_name = &cur_xino->f_dentry->d_name;
+                       skip = (cur_parent == parent
+                               && dname->len == cur_name->len
+                               && !memcmp(dname->name, cur_name->name,
+                                          dname->len));
+                       dput(cur_parent);
+               }
+               if (skip)
+                       goto out;
+       }
+
+       au_opt_set(sbinfo->si_mntflags, XINO);
+       dir = parent->d_inode;
+       mutex_lock_nested(&dir->i_mutex, AuLsc_I_PARENT);
+       /* mnt_want_write() is unnecessary here */
+       err = au_xino_set_xib(sb, xino->file);
+       if (!err)
+               err = au_xigen_set(sb, xino->file);
+       if (!err)
+               err = au_xino_set_br(sb, xino->file);
+       mutex_unlock(&dir->i_mutex);
+       if (!err)
+               goto out; /* success */
+
+       /* reset all */
+       AuIOErr("failed creating xino(%d).\n", err);
+
+ out:
+       dput(parent);
+       return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * create a xinofile at the default place/path.
+ */
+struct file *au_xino_def(struct super_block *sb)
+{
+       struct file *file;
+       char *page, *p;
+       struct au_branch *br;
+       struct super_block *h_sb;
+       struct path path;
+       aufs_bindex_t bend, bindex, bwr;
+
+       br = NULL;
+       bend = au_sbend(sb);
+       bwr = -1;
+       for (bindex = 0; bindex <= bend; bindex++) {
+               br = au_sbr(sb, bindex);
+               if (au_br_writable(br->br_perm)
+                   && !au_test_fs_bad_xino(br->br_mnt->mnt_sb)) {
+                       bwr = bindex;
+                       break;
+               }
+       }
+
+       if (bwr >= 0) {
+               file = ERR_PTR(-ENOMEM);
+               page = __getname();
+               if (unlikely(!page))
+                       goto out;
+               path.mnt = br->br_mnt;
+               path.dentry = au_h_dptr(sb->s_root, bwr);
+               p = d_path(&path, page, PATH_MAX - sizeof(AUFS_XINO_FNAME));
+               file = (void *)p;
+               if (!IS_ERR(p)) {
+                       strcat(p, "/" AUFS_XINO_FNAME);
+                       AuDbg("%s\n", p);
+                       file = au_xino_create(sb, p, /*silent*/0);
+                       if (!IS_ERR(file))
+                               au_xino_brid_set(sb, br->br_id);
+               }
+               __putname(page);
+       } else {
+               file = au_xino_create(sb, AUFS_XINO_DEFPATH, /*silent*/0);
+               if (IS_ERR(file))
+                       goto out;
+               h_sb = file->f_dentry->d_sb;
+               if (unlikely(au_test_fs_bad_xino(h_sb))) {
+                       AuErr("xino doesn't support %s(%s)\n",
+                             AUFS_XINO_DEFPATH, au_sbtype(h_sb));
+                       fput(file);
+                       file = ERR_PTR(-EINVAL);
+               }
+               if (!IS_ERR(file))
+                       au_xino_brid_set(sb, -1);
+       }
+
+ out:
+       return file;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_xino_path(struct seq_file *seq, struct file *file)
+{
+       int err;
+
+       err = au_seq_path(seq, &file->f_path);
+       if (unlikely(err < 0))
+               goto out;
+
+       err = 0;
+#define Deleted "\\040(deleted)"
+       seq->count -= sizeof(Deleted) - 1;
+       AuDebugOn(memcmp(seq->buf + seq->count, Deleted,
+                        sizeof(Deleted) - 1));
+#undef Deleted
+
+ out:
+       return err;
+}
diff --git a/fs/namei.c b/fs/namei.c
index bbc15c2..db581b4 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1196,7 +1196,7 @@ out:
  * needs parent already locked. Doesn't follow mounts.
  * SMP-safe.
  */
-static struct dentry *lookup_hash(struct nameidata *nd)
+struct dentry *lookup_hash(struct nameidata *nd)
 {
        int err;
 
@@ -1206,7 +1206,7 @@ static struct dentry *lookup_hash(struct nameidata *nd)
        return __lookup_hash(&nd->last, nd->path.dentry, nd);
 }
 
-static int __lookup_one_len(const char *name, struct qstr *this,
+int __lookup_one_len(const char *name, struct qstr *this,
                struct dentry *base, int len)
 {
        unsigned long hash;
diff --git a/fs/splice.c b/fs/splice.c
index 4ed0ba4..2fb3d17 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -888,8 +888,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
 /*
  * Attempt to initiate a splice from pipe to file.
  */
-static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
-                          loff_t *ppos, size_t len, unsigned int flags)
+long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+                   loff_t *ppos, size_t len, unsigned int flags)
 {
        int ret;
 
@@ -912,9 +912,9 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 /*
  * Attempt to initiate a splice from a file to a pipe.
  */
-static long do_splice_to(struct file *in, loff_t *ppos,
-                        struct pipe_inode_info *pipe, size_t len,
-                        unsigned int flags)
+long do_splice_to(struct file *in, loff_t *ppos,
+                 struct pipe_inode_info *pipe, size_t len,
+                 unsigned int flags)
 {
        int ret;
 
diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index 106c3ba..d0c7262 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -34,6 +34,7 @@ header-y += atmppp.h
 header-y += atmsap.h
 header-y += atmsvc.h
 header-y += atm_zatm.h
+header-y += aufs_type.h
 header-y += auto_fs4.h
 header-y += ax25.h
 header-y += b1lli.h
diff --git a/include/linux/aufs_type.h b/include/linux/aufs_type.h
new file mode 100644
index 0000000..5c98a5f
--- /dev/null
+++ b/include/linux/aufs_type.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __AUFS_TYPE_H__
+#define __AUFS_TYPE_H__
+
+#include <linux/ioctl.h>
+
+#define AUFS_VERSION   "2-29"
+
+/* todo? move this to linux-2.6.19/include/magic.h */
+#define AUFS_SUPER_MAGIC       ('a' << 24 | 'u' << 16 | 'f' << 8 | 's')
+
+/* ---------------------------------------------------------------------- */
+
+#ifdef CONFIG_AUFS_BRANCH_MAX_127
+/* some environments treat 'char' as 'unsigned char' by default */
+typedef signed char aufs_bindex_t;
+#define AUFS_BRANCH_MAX 127
+#else
+typedef short aufs_bindex_t;
+#ifdef CONFIG_AUFS_BRANCH_MAX_511
+#define AUFS_BRANCH_MAX 511
+#elif defined(CONFIG_AUFS_BRANCH_MAX_1023)
+#define AUFS_BRANCH_MAX 1023
+#elif defined(CONFIG_AUFS_BRANCH_MAX_32767)
+#define AUFS_BRANCH_MAX 32767
+#endif
+#endif
+
+#ifdef __KERNEL__
+#ifndef AUFS_BRANCH_MAX
+#error unknown CONFIG_AUFS_BRANCH_MAX value
+#endif
+#endif /* __KERNEL__ */
+
+/* ---------------------------------------------------------------------- */
+
+#define AUFS_NAME              "aufs"
+#define AUFS_FSTYPE            AUFS_NAME
+
+#define AUFS_ROOT_INO          2
+#define AUFS_FIRST_INO         11
+
+#define AUFS_WH_PFX            ".wh."
+#define AUFS_WH_PFX_LEN                ((int)sizeof(AUFS_WH_PFX) - 1)
+#define AUFS_XINO_FNAME                "." AUFS_NAME ".xino"
+#define AUFS_XINO_DEFPATH      "/tmp/" AUFS_XINO_FNAME
+#define AUFS_XINO_TRUNC_INIT   64 /* blocks */
+#define AUFS_XINO_TRUNC_STEP   4  /* blocks */
+#define AUFS_DIRWH_DEF         3
+#define AUFS_RDCACHE_DEF       10 /* seconds */
+#define AUFS_RDBLK_DEF         512 /* bytes */
+#define AUFS_RDHASH_DEF                32
+#define AUFS_WKQ_NAME          AUFS_NAME "d"
+#define AUFS_NWKQ_DEF          4
+#define AUFS_MFS_SECOND_DEF    30 /* seconds */
+#define AUFS_PLINK_WARN                100 /* number of plinks */
+
+#define AUFS_DIROPQ_NAME       AUFS_WH_PFX ".opq" /* whiteouted doubly */
+#define AUFS_WH_DIROPQ         AUFS_WH_PFX AUFS_DIROPQ_NAME
+
+#define AUFS_BASE_NAME         AUFS_WH_PFX AUFS_NAME
+#define AUFS_PLINKDIR_NAME     AUFS_WH_PFX "plnk"
+#define AUFS_ORPHDIR_NAME      AUFS_WH_PFX "orph"
+
+/* doubly whiteouted */
+#define AUFS_WH_BASE           AUFS_WH_PFX AUFS_BASE_NAME
+#define AUFS_WH_PLINKDIR       AUFS_WH_PFX AUFS_PLINKDIR_NAME
+#define AUFS_WH_ORPHDIR                AUFS_WH_PFX AUFS_ORPHDIR_NAME
+
+/* branch permission */
+#define AUFS_BRPERM_RW         "rw"
+#define AUFS_BRPERM_RO         "ro"
+#define AUFS_BRPERM_RR         "rr"
+#define AUFS_BRPERM_WH         "wh"
+#define AUFS_BRPERM_NLWH       "nolwh"
+#define AUFS_BRPERM_ROWH       AUFS_BRPERM_RO "+" AUFS_BRPERM_WH
+#define AUFS_BRPERM_RRWH       AUFS_BRPERM_RR "+" AUFS_BRPERM_WH
+#define AUFS_BRPERM_RWNLWH     AUFS_BRPERM_RW "+" AUFS_BRPERM_NLWH
+
+/* ---------------------------------------------------------------------- */
+
+/* ioctl */
+enum {
+       AuCtl_PLINK_MAINT,
+       AuCtl_PLINK_CLEAN
+};
+
+#define AuCtlType              'A'
+#define AUFS_CTL_PLINK_MAINT   _IO(AuCtlType, AuCtl_PLINK_MAINT)
+#define AUFS_CTL_PLINK_CLEAN   _IO(AuCtlType, AuCtl_PLINK_CLEAN)
+
+#endif /* __AUFS_TYPE_H__ */
diff --git a/include/linux/namei.h b/include/linux/namei.h
index fc2e035..182d43b 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -75,6 +75,9 @@ extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry
 extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
 extern void release_open_intent(struct nameidata *);
 
+extern struct dentry *lookup_hash(struct nameidata *nd);
+extern int __lookup_one_len(const char *name, struct qstr *this,
+                           struct dentry *base, int len);
 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry *lookup_one_noperm(const char *, struct dentry *);
 
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 528dcb9..5123bc6 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -71,4 +71,10 @@ extern ssize_t splice_to_pipe(struct pipe_inode_info *,
 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
                                      splice_direct_actor *);
 
+extern long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+                          loff_t *ppos, size_t len, unsigned int flags);
+extern long do_splice_to(struct file *in, loff_t *ppos,
+                        struct pipe_inode_info *pipe, size_t len,
+                        unsigned int flags);
+
 #endif