--- /dev/null
+From e2a8296131e94ad785f5564156ed2db1fdb2e080 Mon Sep 17 00:00:00 2001
+From: Coleman Kane <ckane@colemankane.org>
+Date: Sat, 20 Mar 2021 00:00:59 -0400
+Subject: [PATCH] Linux 5.12 compat: idmapped mounts
+
+In Linux 5.12, the filesystem API was modified to support ipmapped
+mounts by adding a "struct user_namespace *" parameter to a number
+functions and VFS handlers. This change adds the needed autoconf
+macros to detect the new interfaces and updates the code appropriately.
+This change does not add support for idmapped mounts, instead it
+preserves the existing behavior by passing the initial user namespace
+where needed. A subsequent commit will be required to add support
+for idmapped mounted.
+
+Reviewed-by: Tony Hutter <hutter2@llnl.gov>
+Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
+Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
+Signed-off-by: Coleman Kane <ckane@colemankane.org>
+Closes #11712
+---
+ config/kernel-generic_fillattr.m4 | 28 +++++++
+ config/kernel-inode-create.m4 | 43 +++++++++--
+ config/kernel-inode-getattr.m4 | 63 +++++++++++++---
+ config/kernel-is_owner_or_cap.m4 | 23 +++++-
+ config/kernel-mkdir-umode-t.m4 | 32 --------
+ config/kernel-mkdir.m4 | 65 ++++++++++++++++
+ config/kernel-mknod.m4 | 30 ++++++++
+ config/kernel-rename.m4 | 50 ++++++++++---
+ config/kernel-setattr-prepare.m4 | 45 ++++++++---
+ config/kernel-symlink.m4 | 30 ++++++++
+ config/kernel-xattr-handler.m4 | 78 +++++++++++++-------
+ config/kernel.m4 | 18 +++--
+ include/os/linux/kernel/linux/vfs_compat.h | 24 +++++-
+ include/os/linux/kernel/linux/xattr_compat.h | 17 ++++-
+ include/os/linux/zfs/sys/zfs_vnops_os.h | 3 +-
+ include/os/linux/zfs/sys/zpl.h | 18 +++++
+ module/os/linux/zfs/policy.c | 2 +-
+ module/os/linux/zfs/zfs_vnops_os.c | 5 +-
+ module/os/linux/zfs/zpl_ctldir.c | 51 ++++++++++++-
+ module/os/linux/zfs/zpl_file.c | 2 +-
+ module/os/linux/zfs/zpl_inode.c | 49 +++++++++++-
+ module/os/linux/zfs/zpl_xattr.c | 4 +-
+ 22 files changed, 557 insertions(+), 123 deletions(-)
+ create mode 100644 config/kernel-generic_fillattr.m4
+ delete mode 100644 config/kernel-mkdir-umode-t.m4
+ create mode 100644 config/kernel-mkdir.m4
+ create mode 100644 config/kernel-mknod.m4
+ create mode 100644 config/kernel-symlink.m4
+
+diff --git a/config/kernel-generic_fillattr.m4 b/config/kernel-generic_fillattr.m4
+new file mode 100644
+index 00000000000..50c8031305b
+--- /dev/null
++++ b/config/kernel-generic_fillattr.m4
+@@ -0,0 +1,28 @@
++dnl #
++dnl # 5.12 API
++dnl #
++dnl # generic_fillattr in linux/fs.h now requires a struct user_namespace*
++dnl # as the first arg, to support idmapped mounts.
++dnl #
++AC_DEFUN([ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS], [
++ ZFS_LINUX_TEST_SRC([generic_fillattr_userns], [
++ #include <linux/fs.h>
++ ],[
++ struct user_namespace *userns = NULL;
++ struct inode *in = NULL;
++ struct kstat *k = NULL;
++ generic_fillattr(userns, in, k);
++ ])
++])
++
++AC_DEFUN([ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS], [
++ AC_MSG_CHECKING([whether generic_fillattr requres struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT([generic_fillattr_userns], [
++ AC_MSG_RESULT([yes])
++ AC_DEFINE(HAVE_GENERIC_FILLATTR_USERNS, 1,
++ [generic_fillattr requires struct user_namespace*])
++ ],[
++ AC_MSG_RESULT([no])
++ ])
++])
++
+diff --git a/config/kernel-inode-create.m4 b/config/kernel-inode-create.m4
+index 9f28bcbd4f7..a6ea11fb61b 100644
+--- a/config/kernel-inode-create.m4
++++ b/config/kernel-inode-create.m4
+@@ -1,7 +1,25 @@
+-dnl #
+-dnl # 3.6 API change
+-dnl #
+-AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE_FLAGS], [
++AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE], [
++ dnl #
++ dnl # 5.12 API change that added the struct user_namespace* arg
++ dnl # to the front of this function type's arg list.
++ dnl #
++ ZFS_LINUX_TEST_SRC([create_userns], [
++ #include <linux/fs.h>
++ #include <linux/sched.h>
++
++ int inode_create(struct user_namespace *userns,
++ struct inode *inode ,struct dentry *dentry,
++ umode_t umode, bool flag) { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .create = inode_create,
++ };
++ ],[])
++
++ dnl #
++ dnl # 3.6 API change
++ dnl #
+ ZFS_LINUX_TEST_SRC([create_flags], [
+ #include <linux/fs.h>
+ #include <linux/sched.h>
+@@ -16,11 +34,20 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE_FLAGS], [
+ ],[])
+ ])
+
+-AC_DEFUN([ZFS_AC_KERNEL_CREATE_FLAGS], [
+- AC_MSG_CHECKING([whether iops->create() passes flags])
+- ZFS_LINUX_TEST_RESULT([create_flags], [
++AC_DEFUN([ZFS_AC_KERNEL_CREATE], [
++ AC_MSG_CHECKING([whether iops->create() takes struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT([create_userns], [
+ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_IOPS_CREATE_USERNS, 1,
++ [iops->create() takes struct user_namespace*])
+ ],[
+- ZFS_LINUX_TEST_ERROR([iops->create()])
++ AC_MSG_RESULT(no)
++
++ AC_MSG_CHECKING([whether iops->create() passes flags])
++ ZFS_LINUX_TEST_RESULT([create_flags], [
++ AC_MSG_RESULT(yes)
++ ],[
++ ZFS_LINUX_TEST_ERROR([iops->create()])
++ ])
+ ])
+ ])
+diff --git a/config/kernel-inode-getattr.m4 b/config/kernel-inode-getattr.m4
+index 48391d66f8b..f62e82f5230 100644
+--- a/config/kernel-inode-getattr.m4
++++ b/config/kernel-inode-getattr.m4
+@@ -1,8 +1,29 @@
+-dnl #
+-dnl # Linux 4.11 API
+-dnl # See torvalds/linux@a528d35
+-dnl #
+ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_GETATTR], [
++ dnl #
++ dnl # Linux 5.12 API
++ dnl # The getattr I/O operations handler type was extended to require
++ dnl # a struct user_namespace* as its first arg, to support idmapped
++ dnl # mounts.
++ dnl #
++ ZFS_LINUX_TEST_SRC([inode_operations_getattr_userns], [
++ #include <linux/fs.h>
++
++ int test_getattr(
++ struct user_namespace *userns,
++ const struct path *p, struct kstat *k,
++ u32 request_mask, unsigned int query_flags)
++ { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .getattr = test_getattr,
++ };
++ ],[])
++
++ dnl #
++ dnl # Linux 4.11 API
++ dnl # See torvalds/linux@a528d35
++ dnl #
+ ZFS_LINUX_TEST_SRC([inode_operations_getattr_path], [
+ #include <linux/fs.h>
+
+@@ -33,21 +54,39 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_GETATTR], [
+ ])
+
+ AC_DEFUN([ZFS_AC_KERNEL_INODE_GETATTR], [
+- AC_MSG_CHECKING([whether iops->getattr() takes a path])
+- ZFS_LINUX_TEST_RESULT([inode_operations_getattr_path], [
++ dnl #
++ dnl # Kernel 5.12 test
++ dnl #
++ AC_MSG_CHECKING([whether iops->getattr() takes user_namespace])
++ ZFS_LINUX_TEST_RESULT([inode_operations_getattr_userns], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_PATH_IOPS_GETATTR, 1,
+- [iops->getattr() takes a path])
++ AC_DEFINE(HAVE_USERNS_IOPS_GETATTR, 1,
++ [iops->getattr() takes struct user_namespace*])
+ ],[
+ AC_MSG_RESULT(no)
+
+- AC_MSG_CHECKING([whether iops->getattr() takes a vfsmount])
+- ZFS_LINUX_TEST_RESULT([inode_operations_getattr_vfsmount], [
++ dnl #
++ dnl # Kernel 4.11 test
++ dnl #
++ AC_MSG_CHECKING([whether iops->getattr() takes a path])
++ ZFS_LINUX_TEST_RESULT([inode_operations_getattr_path], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_VFSMOUNT_IOPS_GETATTR, 1,
+- [iops->getattr() takes a vfsmount])
++ AC_DEFINE(HAVE_PATH_IOPS_GETATTR, 1,
++ [iops->getattr() takes a path])
+ ],[
+ AC_MSG_RESULT(no)
++
++ dnl #
++ dnl # Kernel < 4.11 test
++ dnl #
++ AC_MSG_CHECKING([whether iops->getattr() takes a vfsmount])
++ ZFS_LINUX_TEST_RESULT([inode_operations_getattr_vfsmount], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_VFSMOUNT_IOPS_GETATTR, 1,
++ [iops->getattr() takes a vfsmount])
++ ],[
++ AC_MSG_RESULT(no)
++ ])
+ ])
+ ])
+ ])
+diff --git a/config/kernel-is_owner_or_cap.m4 b/config/kernel-is_owner_or_cap.m4
+index 3df6163da27..3c3c6ad2240 100644
+--- a/config/kernel-is_owner_or_cap.m4
++++ b/config/kernel-is_owner_or_cap.m4
+@@ -11,13 +11,32 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_OWNER_OR_CAPABLE], [
+ struct inode *ip = NULL;
+ (void) inode_owner_or_capable(ip);
+ ])
++
++ ZFS_LINUX_TEST_SRC([inode_owner_or_capable_idmapped], [
++ #include <linux/fs.h>
++ ],[
++ struct inode *ip = NULL;
++ (void) inode_owner_or_capable(&init_user_ns, ip);
++ ])
+ ])
+
+ AC_DEFUN([ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE], [
+ AC_MSG_CHECKING([whether inode_owner_or_capable() exists])
+ ZFS_LINUX_TEST_RESULT([inode_owner_or_capable], [
+ AC_MSG_RESULT(yes)
+- ],[
+- ZFS_LINUX_TEST_ERROR([capability])
++ AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE, 1,
++ [inode_owner_or_capable() exists])
++ ], [
++ AC_MSG_RESULT(no)
++
++ AC_MSG_CHECKING(
++ [whether inode_owner_or_capable() takes user_ns])
++ ZFS_LINUX_TEST_RESULT([inode_owner_or_capable_idmapped], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE_IDMAPPED, 1,
++ [inode_owner_or_capable() takes user_ns])
++ ],[
++ ZFS_LINUX_TEST_ERROR([capability])
++ ])
+ ])
+ ])
+diff --git a/config/kernel-mkdir-umode-t.m4 b/config/kernel-mkdir-umode-t.m4
+deleted file mode 100644
+index 19599670df3..00000000000
+--- a/config/kernel-mkdir-umode-t.m4
++++ /dev/null
+@@ -1,32 +0,0 @@
+-dnl #
+-dnl # 3.3 API change
+-dnl # The VFS .create, .mkdir and .mknod callbacks were updated to take a
+-dnl # umode_t type rather than an int. The expectation is that any backport
+-dnl # would also change all three prototypes. However, if it turns out that
+-dnl # some distribution doesn't backport the whole thing this could be
+-dnl # broken apart into three separate checks.
+-dnl #
+-AC_DEFUN([ZFS_AC_KERNEL_SRC_MKDIR_UMODE_T], [
+- ZFS_LINUX_TEST_SRC([inode_operations_mkdir], [
+- #include <linux/fs.h>
+-
+- int mkdir(struct inode *inode, struct dentry *dentry,
+- umode_t umode) { return 0; }
+-
+- static const struct inode_operations
+- iops __attribute__ ((unused)) = {
+- .mkdir = mkdir,
+- };
+- ],[])
+-])
+-
+-AC_DEFUN([ZFS_AC_KERNEL_MKDIR_UMODE_T], [
+- AC_MSG_CHECKING([whether iops->create()/mkdir()/mknod() take umode_t])
+- ZFS_LINUX_TEST_RESULT([inode_operations_mkdir], [
+- AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_MKDIR_UMODE_T, 1,
+- [iops->create()/mkdir()/mknod() take umode_t])
+- ],[
+- ZFS_LINUX_TEST_ERROR([mkdir()])
+- ])
+-])
+diff --git a/config/kernel-mkdir.m4 b/config/kernel-mkdir.m4
+new file mode 100644
+index 00000000000..a162bcd880f
+--- /dev/null
++++ b/config/kernel-mkdir.m4
+@@ -0,0 +1,65 @@
++dnl #
++dnl # Supported mkdir() interfaces checked newest to oldest.
++dnl #
++AC_DEFUN([ZFS_AC_KERNEL_SRC_MKDIR], [
++ dnl #
++ dnl # 5.12 API change
++ dnl # The struct user_namespace arg was added as the first argument to
++ dnl # mkdir()
++ dnl #
++ ZFS_LINUX_TEST_SRC([mkdir_user_namespace], [
++ #include <linux/fs.h>
++
++ int mkdir(struct user_namespace *userns,
++ struct inode *inode, struct dentry *dentry,
++ umode_t umode) { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .mkdir = mkdir,
++ };
++ ],[])
++
++ dnl #
++ dnl # 3.3 API change
++ dnl # The VFS .create, .mkdir and .mknod callbacks were updated to take a
++ dnl # umode_t type rather than an int. The expectation is that any backport
++ dnl # would also change all three prototypes. However, if it turns out that
++ dnl # some distribution doesn't backport the whole thing this could be
++ dnl # broken apart into three separate checks.
++ dnl #
++ ZFS_LINUX_TEST_SRC([inode_operations_mkdir], [
++ #include <linux/fs.h>
++
++ int mkdir(struct inode *inode, struct dentry *dentry,
++ umode_t umode) { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .mkdir = mkdir,
++ };
++ ],[])
++])
++
++AC_DEFUN([ZFS_AC_KERNEL_MKDIR], [
++ dnl #
++ dnl # 5.12 API change
++ dnl # The struct user_namespace arg was added as the first argument to
++ dnl # mkdir() of the iops structure.
++ dnl #
++ AC_MSG_CHECKING([whether iops->mkdir() takes struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT([mkdir_user_namespace], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_IOPS_MKDIR_USERNS, 1,
++ [iops->mkdir() takes struct user_namespace*])
++ ],[
++ AC_MSG_CHECKING([whether iops->mkdir() takes umode_t])
++ ZFS_LINUX_TEST_RESULT([inode_operations_mkdir], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_MKDIR_UMODE_T, 1,
++ [iops->mkdir() takes umode_t])
++ ],[
++ ZFS_LINUX_TEST_ERROR([mkdir()])
++ ])
++ ])
++])
+diff --git a/config/kernel-mknod.m4 b/config/kernel-mknod.m4
+new file mode 100644
+index 00000000000..ffe45106003
+--- /dev/null
++++ b/config/kernel-mknod.m4
+@@ -0,0 +1,30 @@
++AC_DEFUN([ZFS_AC_KERNEL_SRC_MKNOD], [
++ dnl #
++ dnl # 5.12 API change that added the struct user_namespace* arg
++ dnl # to the front of this function type's arg list.
++ dnl #
++ ZFS_LINUX_TEST_SRC([mknod_userns], [
++ #include <linux/fs.h>
++ #include <linux/sched.h>
++
++ int tmp_mknod(struct user_namespace *userns,
++ struct inode *inode ,struct dentry *dentry,
++ umode_t u, dev_t d) { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .mknod = tmp_mknod,
++ };
++ ],[])
++])
++
++AC_DEFUN([ZFS_AC_KERNEL_MKNOD], [
++ AC_MSG_CHECKING([whether iops->mknod() takes struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT([mknod_userns], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_IOPS_MKNOD_USERNS, 1,
++ [iops->mknod() takes struct user_namespace*])
++ ],[
++ AC_MSG_RESULT(no)
++ ])
++])
+diff --git a/config/kernel-rename.m4 b/config/kernel-rename.m4
+index f707391539d..31d199f33bb 100644
+--- a/config/kernel-rename.m4
++++ b/config/kernel-rename.m4
+@@ -1,10 +1,10 @@
+-dnl #
+-dnl # 4.9 API change,
+-dnl # iops->rename2() merged into iops->rename(), and iops->rename() now wants
+-dnl # flags.
+-dnl #
+-AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME_WANTS_FLAGS], [
+- ZFS_LINUX_TEST_SRC([inode_operations_rename], [
++AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME], [
++ dnl #
++ dnl # 4.9 API change,
++ dnl # iops->rename2() merged into iops->rename(), and iops->rename() now wants
++ dnl # flags.
++ dnl #
++ ZFS_LINUX_TEST_SRC([inode_operations_rename_flags], [
+ #include <linux/fs.h>
+ int rename_fn(struct inode *sip, struct dentry *sdp,
+ struct inode *tip, struct dentry *tdp,
+@@ -15,15 +15,41 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME_WANTS_FLAGS], [
+ .rename = rename_fn,
+ };
+ ],[])
++
++ dnl #
++ dnl # 5.12 API change,
++ dnl #
++ dnl # Linux 5.12 introduced passing struct user_namespace* as the first argument
++ dnl # of the rename() and other inode_operations members.
++ dnl #
++ ZFS_LINUX_TEST_SRC([inode_operations_rename_userns], [
++ #include <linux/fs.h>
++ int rename_fn(struct user_namespace *user_ns, struct inode *sip,
++ struct dentry *sdp, struct inode *tip, struct dentry *tdp,
++ unsigned int flags) { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .rename = rename_fn,
++ };
++ ],[])
+ ])
+
+-AC_DEFUN([ZFS_AC_KERNEL_RENAME_WANTS_FLAGS], [
+- AC_MSG_CHECKING([whether iops->rename() wants flags])
+- ZFS_LINUX_TEST_RESULT([inode_operations_rename], [
++AC_DEFUN([ZFS_AC_KERNEL_RENAME], [
++ AC_MSG_CHECKING([whether iops->rename() takes struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT([inode_operations_rename_userns], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_RENAME_WANTS_FLAGS, 1,
+- [iops->rename() wants flags])
++ AC_DEFINE(HAVE_IOPS_RENAME_USERNS, 1,
++ [iops->rename() takes struct user_namespace*])
+ ],[
+ AC_MSG_RESULT(no)
++
++ ZFS_LINUX_TEST_RESULT([inode_operations_rename_flags], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_RENAME_WANTS_FLAGS, 1,
++ [iops->rename() wants flags])
++ ],[
++ AC_MSG_RESULT(no)
++ ])
+ ])
+ ])
+diff --git a/config/kernel-setattr-prepare.m4 b/config/kernel-setattr-prepare.m4
+index 45408c45c69..24245aa5344 100644
+--- a/config/kernel-setattr-prepare.m4
++++ b/config/kernel-setattr-prepare.m4
+@@ -1,27 +1,52 @@
+-dnl #
+-dnl # 4.9 API change
+-dnl # The inode_change_ok() function has been renamed setattr_prepare()
+-dnl # and updated to take a dentry rather than an inode.
+-dnl #
+ AC_DEFUN([ZFS_AC_KERNEL_SRC_SETATTR_PREPARE], [
++ dnl #
++ dnl # 4.9 API change
++ dnl # The inode_change_ok() function has been renamed setattr_prepare()
++ dnl # and updated to take a dentry rather than an inode.
++ dnl #
+ ZFS_LINUX_TEST_SRC([setattr_prepare], [
+ #include <linux/fs.h>
+ ], [
+ struct dentry *dentry = NULL;
+ struct iattr *attr = NULL;
+ int error __attribute__ ((unused)) =
+- setattr_prepare(dentry, attr);
++ setattr_prepare(dentry, attr);
++ ])
++
++ dnl #
++ dnl # 5.12 API change
++ dnl # The setattr_prepare() function has been changed to accept a new argument
++ dnl # for struct user_namespace*
++ dnl #
++ ZFS_LINUX_TEST_SRC([setattr_prepare_userns], [
++ #include <linux/fs.h>
++ ], [
++ struct dentry *dentry = NULL;
++ struct iattr *attr = NULL;
++ struct user_namespace *userns = NULL;
++ int error __attribute__ ((unused)) =
++ setattr_prepare(userns, dentry, attr);
+ ])
+ ])
+
+ AC_DEFUN([ZFS_AC_KERNEL_SETATTR_PREPARE], [
+- AC_MSG_CHECKING([whether setattr_prepare() is available])
+- ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare],
++ AC_MSG_CHECKING([whether setattr_prepare() is available and accepts struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare_userns],
+ [setattr_prepare], [fs/attr.c], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_SETATTR_PREPARE, 1,
+- [setattr_prepare() is available])
++ AC_DEFINE(HAVE_SETATTR_PREPARE_USERNS, 1,
++ [setattr_prepare() accepts user_namespace])
+ ], [
+ AC_MSG_RESULT(no)
++
++ AC_MSG_CHECKING([whether setattr_prepare() is available, doesn't accept user_namespace])
++ ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare],
++ [setattr_prepare], [fs/attr.c], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_SETATTR_PREPARE_NO_USERNS, 1,
++ [setattr_prepare() is available, doesn't accept user_namespace])
++ ], [
++ AC_MSG_RESULT(no)
++ ])
+ ])
+ ])
+diff --git a/config/kernel-symlink.m4 b/config/kernel-symlink.m4
+new file mode 100644
+index 00000000000..d90366d04b7
+--- /dev/null
++++ b/config/kernel-symlink.m4
+@@ -0,0 +1,30 @@
++AC_DEFUN([ZFS_AC_KERNEL_SRC_SYMLINK], [
++ dnl #
++ dnl # 5.12 API change that added the struct user_namespace* arg
++ dnl # to the front of this function type's arg list.
++ dnl #
++ ZFS_LINUX_TEST_SRC([symlink_userns], [
++ #include <linux/fs.h>
++ #include <linux/sched.h>
++
++ int tmp_symlink(struct user_namespace *userns,
++ struct inode *inode ,struct dentry *dentry,
++ const char *path) { return 0; }
++
++ static const struct inode_operations
++ iops __attribute__ ((unused)) = {
++ .symlink = tmp_symlink,
++ };
++ ],[])
++])
++
++AC_DEFUN([ZFS_AC_KERNEL_SYMLINK], [
++ AC_MSG_CHECKING([whether iops->symlink() takes struct user_namespace*])
++ ZFS_LINUX_TEST_RESULT([symlink_userns], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_IOPS_SYMLINK_USERNS, 1,
++ [iops->symlink() takes struct user_namespace*])
++ ],[
++ AC_MSG_RESULT(no)
++ ])
++])
+diff --git a/config/kernel-xattr-handler.m4 b/config/kernel-xattr-handler.m4
+index 137bf4a8aff..00b1e74a9cc 100644
+--- a/config/kernel-xattr-handler.m4
++++ b/config/kernel-xattr-handler.m4
+@@ -152,6 +152,21 @@ dnl #
+ dnl # Supported xattr handler set() interfaces checked newest to oldest.
+ dnl #
+ AC_DEFUN([ZFS_AC_KERNEL_SRC_XATTR_HANDLER_SET], [
++ ZFS_LINUX_TEST_SRC([xattr_handler_set_userns], [
++ #include <linux/xattr.h>
++
++ int set(const struct xattr_handler *handler,
++ struct user_namespace *mnt_userns,
++ struct dentry *dentry, struct inode *inode,
++ const char *name, const void *buffer,
++ size_t size, int flags)
++ { return 0; }
++ static const struct xattr_handler
++ xops __attribute__ ((unused)) = {
++ .set = set,
++ };
++ ],[])
++
+ ZFS_LINUX_TEST_SRC([xattr_handler_set_dentry_inode], [
+ #include <linux/xattr.h>
+
+@@ -194,45 +209,58 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_XATTR_HANDLER_SET], [
+
+ AC_DEFUN([ZFS_AC_KERNEL_XATTR_HANDLER_SET], [
+ dnl #
+- dnl # 4.7 API change,
+- dnl # The xattr_handler->set() callback was changed to take both
+- dnl # dentry and inode.
++ dnl # 5.12 API change,
++ dnl # The xattr_handler->set() callback was changed to 8 arguments, and
++ dnl # struct user_namespace* was inserted as arg #2
+ dnl #
+- AC_MSG_CHECKING([whether xattr_handler->set() wants dentry and inode])
+- ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry_inode], [
++ AC_MSG_CHECKING([whether xattr_handler->set() wants dentry, inode, and user_namespace])
++ ZFS_LINUX_TEST_RESULT([xattr_handler_set_userns], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_XATTR_SET_DENTRY_INODE, 1,
+- [xattr_handler->set() wants both dentry and inode])
++ AC_DEFINE(HAVE_XATTR_SET_USERNS, 1,
++ [xattr_handler->set() takes user_namespace])
+ ],[
+ dnl #
+- dnl # 4.4 API change,
+- dnl # The xattr_handler->set() callback was changed to take a
+- dnl # xattr_handler, and handler_flags argument was removed and
+- dnl # should be accessed by handler->flags.
++ dnl # 4.7 API change,
++ dnl # The xattr_handler->set() callback was changed to take both
++ dnl # dentry and inode.
+ dnl #
+ AC_MSG_RESULT(no)
+- AC_MSG_CHECKING(
+- [whether xattr_handler->set() wants xattr_handler])
+- ZFS_LINUX_TEST_RESULT([xattr_handler_set_xattr_handler], [
++ AC_MSG_CHECKING([whether xattr_handler->set() wants dentry and inode])
++ ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry_inode], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_XATTR_SET_HANDLER, 1,
+- [xattr_handler->set() wants xattr_handler])
++ AC_DEFINE(HAVE_XATTR_SET_DENTRY_INODE, 1,
++ [xattr_handler->set() wants both dentry and inode])
+ ],[
+ dnl #
+- dnl # 2.6.33 API change,
+- dnl # The xattr_handler->set() callback was changed
+- dnl # to take a dentry instead of an inode, and a
+- dnl # handler_flags argument was added.
++ dnl # 4.4 API change,
++ dnl # The xattr_handler->set() callback was changed to take a
++ dnl # xattr_handler, and handler_flags argument was removed and
++ dnl # should be accessed by handler->flags.
+ dnl #
+ AC_MSG_RESULT(no)
+ AC_MSG_CHECKING(
+- [whether xattr_handler->set() wants dentry])
+- ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry], [
++ [whether xattr_handler->set() wants xattr_handler])
++ ZFS_LINUX_TEST_RESULT([xattr_handler_set_xattr_handler], [
+ AC_MSG_RESULT(yes)
+- AC_DEFINE(HAVE_XATTR_SET_DENTRY, 1,
+- [xattr_handler->set() wants dentry])
++ AC_DEFINE(HAVE_XATTR_SET_HANDLER, 1,
++ [xattr_handler->set() wants xattr_handler])
+ ],[
+- ZFS_LINUX_TEST_ERROR([xattr set()])
++ dnl #
++ dnl # 2.6.33 API change,
++ dnl # The xattr_handler->set() callback was changed
++ dnl # to take a dentry instead of an inode, and a
++ dnl # handler_flags argument was added.
++ dnl #
++ AC_MSG_RESULT(no)
++ AC_MSG_CHECKING(
++ [whether xattr_handler->set() wants dentry])
++ ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry], [
++ AC_MSG_RESULT(yes)
++ AC_DEFINE(HAVE_XATTR_SET_DENTRY, 1,
++ [xattr_handler->set() wants dentry])
++ ],[
++ ZFS_LINUX_TEST_ERROR([xattr set()])
++ ])
+ ])
+ ])
+ ])
+diff --git a/config/kernel.m4 b/config/kernel.m4
+index f31be845f5d..24db38f09f4 100644
+--- a/config/kernel.m4
++++ b/config/kernel.m4
+@@ -79,9 +79,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
+ ZFS_AC_KERNEL_SRC_EVICT_INODE
+ ZFS_AC_KERNEL_SRC_DIRTY_INODE
+ ZFS_AC_KERNEL_SRC_SHRINKER
+- ZFS_AC_KERNEL_SRC_MKDIR_UMODE_T
++ ZFS_AC_KERNEL_SRC_MKDIR
+ ZFS_AC_KERNEL_SRC_LOOKUP_FLAGS
+- ZFS_AC_KERNEL_SRC_CREATE_FLAGS
++ ZFS_AC_KERNEL_SRC_CREATE
+ ZFS_AC_KERNEL_SRC_GET_LINK
+ ZFS_AC_KERNEL_SRC_PUT_LINK
+ ZFS_AC_KERNEL_SRC_TMPFILE
+@@ -115,7 +115,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
+ ZFS_AC_KERNEL_SRC_KUIDGID_T
+ ZFS_AC_KERNEL_SRC_KUID_HELPERS
+ ZFS_AC_KERNEL_SRC_MODULE_PARAM_CALL_CONST
+- ZFS_AC_KERNEL_SRC_RENAME_WANTS_FLAGS
++ ZFS_AC_KERNEL_SRC_RENAME
+ ZFS_AC_KERNEL_SRC_CURRENT_TIME
+ ZFS_AC_KERNEL_SRC_USERNS_CAPABILITIES
+ ZFS_AC_KERNEL_SRC_IN_COMPAT_SYSCALL
+@@ -125,6 +125,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
+ ZFS_AC_KERNEL_SRC_TOTALHIGH_PAGES
+ ZFS_AC_KERNEL_SRC_KSTRTOUL
+ ZFS_AC_KERNEL_SRC_PERCPU
++ ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS
++ ZFS_AC_KERNEL_SRC_MKNOD
++ ZFS_AC_KERNEL_SRC_SYMLINK
+
+ AC_MSG_CHECKING([for available kernel interfaces])
+ ZFS_LINUX_TEST_COMPILE_ALL([kabi])
+@@ -177,9 +180,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
+ ZFS_AC_KERNEL_EVICT_INODE
+ ZFS_AC_KERNEL_DIRTY_INODE
+ ZFS_AC_KERNEL_SHRINKER
+- ZFS_AC_KERNEL_MKDIR_UMODE_T
++ ZFS_AC_KERNEL_MKDIR
+ ZFS_AC_KERNEL_LOOKUP_FLAGS
+- ZFS_AC_KERNEL_CREATE_FLAGS
++ ZFS_AC_KERNEL_CREATE
+ ZFS_AC_KERNEL_GET_LINK
+ ZFS_AC_KERNEL_PUT_LINK
+ ZFS_AC_KERNEL_TMPFILE
+@@ -213,7 +216,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
+ ZFS_AC_KERNEL_KUIDGID_T
+ ZFS_AC_KERNEL_KUID_HELPERS
+ ZFS_AC_KERNEL_MODULE_PARAM_CALL_CONST
+- ZFS_AC_KERNEL_RENAME_WANTS_FLAGS
++ ZFS_AC_KERNEL_RENAME
+ ZFS_AC_KERNEL_CURRENT_TIME
+ ZFS_AC_KERNEL_USERNS_CAPABILITIES
+ ZFS_AC_KERNEL_IN_COMPAT_SYSCALL
+@@ -223,6 +226,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
+ ZFS_AC_KERNEL_TOTALHIGH_PAGES
+ ZFS_AC_KERNEL_KSTRTOUL
+ ZFS_AC_KERNEL_PERCPU
++ ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS
++ ZFS_AC_KERNEL_MKNOD
++ ZFS_AC_KERNEL_SYMLINK
+ ])
+
+ dnl #
+diff --git a/include/os/linux/kernel/linux/vfs_compat.h b/include/os/linux/kernel/linux/vfs_compat.h
+index c35e80d31cd..91e908598fb 100644
+--- a/include/os/linux/kernel/linux/vfs_compat.h
++++ b/include/os/linux/kernel/linux/vfs_compat.h
+@@ -343,7 +343,8 @@ static inline void zfs_gid_write(struct inode *ip, gid_t gid)
+ /*
+ * 4.9 API change
+ */
+-#ifndef HAVE_SETATTR_PREPARE
++#if !(defined(HAVE_SETATTR_PREPARE_NO_USERNS) || \
++ defined(HAVE_SETATTR_PREPARE_USERNS))
+ static inline int
+ setattr_prepare(struct dentry *dentry, struct iattr *ia)
+ {
+@@ -389,6 +390,15 @@ func(const struct path *path, struct kstat *stat, u32 request_mask, \
+ { \
+ return (func##_impl(path, stat, request_mask, query_flags)); \
+ }
++#elif defined(HAVE_USERNS_IOPS_GETATTR)
++#define ZPL_GETATTR_WRAPPER(func) \
++static int \
++func(struct user_namespace *user_ns, const struct path *path, \
++ struct kstat *stat, u32 request_mask, unsigned int query_flags) \
++{ \
++ return (func##_impl(user_ns, path, stat, request_mask, \
++ query_flags)); \
++}
+ #else
+ #error
+ #endif
+@@ -436,4 +446,16 @@ zpl_is_32bit_api(void)
+ #endif
+ }
+
++/*
++ * 5.12 API change
++ * To support id-mapped mounts, generic_fillattr() was modified to
++ * accept a new struct user_namespace* as its first arg.
++ */
++#ifdef HAVE_GENERIC_FILLATTR_USERNS
++#define zpl_generic_fillattr(user_ns, ip, sp) \
++ generic_fillattr(user_ns, ip, sp)
++#else
++#define zpl_generic_fillattr(user_ns, ip, sp) generic_fillattr(ip, sp)
++#endif
++
+ #endif /* _ZFS_VFS_H */
+diff --git a/include/os/linux/kernel/linux/xattr_compat.h b/include/os/linux/kernel/linux/xattr_compat.h
+index 8348e99198a..54690727eab 100644
+--- a/include/os/linux/kernel/linux/xattr_compat.h
++++ b/include/os/linux/kernel/linux/xattr_compat.h
+@@ -119,12 +119,27 @@ fn(struct dentry *dentry, const char *name, void *buffer, size_t size, \
+ #error "Unsupported kernel"
+ #endif
+
++/*
++ * 5.12 API change,
++ * The xattr_handler->set() callback was changed to take the
++ * struct user_namespace* as the first arg, to support idmapped
++ * mounts.
++ */
++#if defined(HAVE_XATTR_SET_USERNS)
++#define ZPL_XATTR_SET_WRAPPER(fn) \
++static int \
++fn(const struct xattr_handler *handler, struct user_namespace *user_ns, \
++ struct dentry *dentry, struct inode *inode, const char *name, \
++ const void *buffer, size_t size, int flags) \
++{ \
++ return (__ ## fn(inode, name, buffer, size, flags)); \
++}
+ /*
+ * 4.7 API change,
+ * The xattr_handler->set() callback was changed to take a both dentry and
+ * inode, because the dentry might not be attached to an inode yet.
+ */
+-#if defined(HAVE_XATTR_SET_DENTRY_INODE)
++#elif defined(HAVE_XATTR_SET_DENTRY_INODE)
+ #define ZPL_XATTR_SET_WRAPPER(fn) \
+ static int \
+ fn(const struct xattr_handler *handler, struct dentry *dentry, \
+diff --git a/include/os/linux/zfs/sys/zfs_vnops_os.h b/include/os/linux/zfs/sys/zfs_vnops_os.h
+index ef76de3e298..47f91e4a6cf 100644
+--- a/include/os/linux/zfs/sys/zfs_vnops_os.h
++++ b/include/os/linux/zfs/sys/zfs_vnops_os.h
+@@ -54,7 +54,8 @@ extern int zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap,
+ extern int zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd,
+ cred_t *cr, int flags);
+ extern int zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr);
+-extern int zfs_getattr_fast(struct inode *ip, struct kstat *sp);
++extern int zfs_getattr_fast(struct user_namespace *, struct inode *ip,
++ struct kstat *sp);
+ extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr);
+ extern int zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp,
+ char *tnm, cred_t *cr, int flags);
+diff --git a/include/os/linux/zfs/sys/zpl.h b/include/os/linux/zfs/sys/zpl.h
+index b0bb9c29c0b..21825d1f378 100644
+--- a/include/os/linux/zfs/sys/zpl.h
++++ b/include/os/linux/zfs/sys/zpl.h
+@@ -171,4 +171,22 @@ zpl_dir_emit_dots(struct file *file, zpl_dir_context_t *ctx)
+ timespec_trunc(ts, (ip)->i_sb->s_time_gran)
+ #endif
+
++#if defined(HAVE_INODE_OWNER_OR_CAPABLE)
++#define zpl_inode_owner_or_capable(ns, ip) inode_owner_or_capable(ip)
++#elif defined(HAVE_INODE_OWNER_OR_CAPABLE_IDMAPPED)
++#define zpl_inode_owner_or_capable(ns, ip) inode_owner_or_capable(ns, ip)
++#else
++#error "Unsupported kernel"
++#endif
++
++#ifdef HAVE_SETATTR_PREPARE_USERNS
++#define zpl_setattr_prepare(ns, dentry, ia) setattr_prepare(ns, dentry, ia)
++#else
++/*
++ * Use kernel-provided version, or our own from
++ * linux/vfs_compat.h
++ */
++#define zpl_setattr_prepare(ns, dentry, ia) setattr_prepare(dentry, ia)
++#endif
++
+ #endif /* _SYS_ZPL_H */
+diff --git a/module/os/linux/zfs/policy.c b/module/os/linux/zfs/policy.c
+index 8780d7f6c70..bbccb2e572d 100644
+--- a/module/os/linux/zfs/policy.c
++++ b/module/os/linux/zfs/policy.c
+@@ -124,7 +124,7 @@ secpolicy_vnode_any_access(const cred_t *cr, struct inode *ip, uid_t owner)
+ if (crgetfsuid(cr) == owner)
+ return (0);
+
+- if (inode_owner_or_capable(ip))
++ if (zpl_inode_owner_or_capable(kcred->user_ns, ip))
+ return (0);
+
+ #if defined(CONFIG_USER_NS)
+diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
+index 84c33b541ea..8aeed6f568c 100644
+--- a/module/os/linux/zfs/zfs_vnops_os.c
++++ b/module/os/linux/zfs/zfs_vnops_os.c
+@@ -1656,7 +1656,8 @@ zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr)
+ */
+ /* ARGSUSED */
+ int
+-zfs_getattr_fast(struct inode *ip, struct kstat *sp)
++zfs_getattr_fast(struct user_namespace *user_ns, struct inode *ip,
++ struct kstat *sp)
+ {
+ znode_t *zp = ITOZ(ip);
+ zfsvfs_t *zfsvfs = ITOZSB(ip);
+@@ -1668,7 +1669,7 @@ zfs_getattr_fast(struct inode *ip, struct kstat *sp)
+
+ mutex_enter(&zp->z_lock);
+
+- generic_fillattr(ip, sp);
++ zpl_generic_fillattr(user_ns, ip, sp);
+ /*
+ * +1 link count for root inode with visible '.zfs' directory.
+ */
+diff --git a/module/os/linux/zfs/zpl_ctldir.c b/module/os/linux/zfs/zpl_ctldir.c
+index e6420f19ed8..9b526afd000 100644
+--- a/module/os/linux/zfs/zpl_ctldir.c
++++ b/module/os/linux/zfs/zpl_ctldir.c
+@@ -101,12 +101,22 @@ zpl_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
+ */
+ /* ARGSUSED */
+ static int
++#ifdef HAVE_USERNS_IOPS_GETATTR
++zpl_root_getattr_impl(struct user_namespace *user_ns,
++ const struct path *path, struct kstat *stat, u32 request_mask,
++ unsigned int query_flags)
++#else
+ zpl_root_getattr_impl(const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
++#endif
+ {
+ struct inode *ip = path->dentry->d_inode;
+
++#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
++ generic_fillattr(user_ns, ip, stat);
++#else
+ generic_fillattr(ip, stat);
++#endif
+ stat->atime = current_time(ip);
+
+ return (0);
+@@ -290,8 +300,14 @@ zpl_snapdir_readdir(struct file *filp, void *dirent, filldir_t filldir)
+ #endif /* !HAVE_VFS_ITERATE && !HAVE_VFS_ITERATE_SHARED */
+
+ static int
++#ifdef HAVE_IOPS_RENAME_USERNS
++zpl_snapdir_rename2(struct user_namespace *user_ns, struct inode *sdip,
++ struct dentry *sdentry, struct inode *tdip, struct dentry *tdentry,
++ unsigned int flags)
++#else
+ zpl_snapdir_rename2(struct inode *sdip, struct dentry *sdentry,
+ struct inode *tdip, struct dentry *tdentry, unsigned int flags)
++#endif
+ {
+ cred_t *cr = CRED();
+ int error;
+@@ -309,7 +325,7 @@ zpl_snapdir_rename2(struct inode *sdip, struct dentry *sdentry,
+ return (error);
+ }
+
+-#ifndef HAVE_RENAME_WANTS_FLAGS
++#if !defined(HAVE_RENAME_WANTS_FLAGS) && !defined(HAVE_IOPS_RENAME_USERNS)
+ static int
+ zpl_snapdir_rename(struct inode *sdip, struct dentry *sdentry,
+ struct inode *tdip, struct dentry *tdentry)
+@@ -333,7 +349,12 @@ zpl_snapdir_rmdir(struct inode *dip, struct dentry *dentry)
+ }
+
+ static int
++#ifdef HAVE_IOPS_MKDIR_USERNS
++zpl_snapdir_mkdir(struct user_namespace *user_ns, struct inode *dip,
++ struct dentry *dentry, umode_t mode)
++#else
+ zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
++#endif
+ {
+ cred_t *cr = CRED();
+ vattr_t *vap;
+@@ -363,14 +384,24 @@ zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
+ */
+ /* ARGSUSED */
+ static int
++#ifdef HAVE_USERNS_IOPS_GETATTR
++zpl_snapdir_getattr_impl(struct user_namespace *user_ns,
++ const struct path *path, struct kstat *stat, u32 request_mask,
++ unsigned int query_flags)
++#else
+ zpl_snapdir_getattr_impl(const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
++#endif
+ {
+ struct inode *ip = path->dentry->d_inode;
+ zfsvfs_t *zfsvfs = ITOZSB(ip);
+
+ ZPL_ENTER(zfsvfs);
++#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
++ generic_fillattr(user_ns, ip, stat);
++#else
+ generic_fillattr(ip, stat);
++#endif
+
+ stat->nlink = stat->size = 2;
+ stat->ctime = stat->mtime = dmu_objset_snap_cmtime(zfsvfs->z_os);
+@@ -408,7 +439,7 @@ const struct file_operations zpl_fops_snapdir = {
+ const struct inode_operations zpl_ops_snapdir = {
+ .lookup = zpl_snapdir_lookup,
+ .getattr = zpl_snapdir_getattr,
+-#ifdef HAVE_RENAME_WANTS_FLAGS
++#if defined(HAVE_RENAME_WANTS_FLAGS) || defined(HAVE_IOPS_RENAME_USERNS)
+ .rename = zpl_snapdir_rename2,
+ #else
+ .rename = zpl_snapdir_rename,
+@@ -495,8 +526,14 @@ zpl_shares_readdir(struct file *filp, void *dirent, filldir_t filldir)
+
+ /* ARGSUSED */
+ static int
++#ifdef HAVE_USERNS_IOPS_GETATTR
++zpl_shares_getattr_impl(struct user_namespace *user_ns,
++ const struct path *path, struct kstat *stat, u32 request_mask,
++ unsigned int query_flags)
++#else
+ zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
++#endif
+ {
+ struct inode *ip = path->dentry->d_inode;
+ zfsvfs_t *zfsvfs = ITOZSB(ip);
+@@ -506,7 +543,11 @@ zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
+ ZPL_ENTER(zfsvfs);
+
+ if (zfsvfs->z_shares_dir == 0) {
++#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
++ generic_fillattr(user_ns, path->dentry->d_inode, stat);
++#else
+ generic_fillattr(path->dentry->d_inode, stat);
++#endif
+ stat->nlink = stat->size = 2;
+ stat->atime = current_time(ip);
+ ZPL_EXIT(zfsvfs);
+@@ -515,7 +556,11 @@ zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
+
+ error = -zfs_zget(zfsvfs, zfsvfs->z_shares_dir, &dzp);
+ if (error == 0) {
+- error = -zfs_getattr_fast(ZTOI(dzp), stat);
++#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
++ error = -zfs_getattr_fast(user_ns, ZTOI(dzp), stat);
++#else
++ error = -zfs_getattr_fast(kcred->user_ns, ZTOI(dzp), stat);
++#endif
+ iput(ZTOI(dzp));
+ }
+
+diff --git a/module/os/linux/zfs/zpl_file.c b/module/os/linux/zfs/zpl_file.c
+index 970db4a8b73..ea6993ffa4b 100644
+--- a/module/os/linux/zfs/zpl_file.c
++++ b/module/os/linux/zfs/zpl_file.c
+@@ -869,7 +869,7 @@ __zpl_ioctl_setflags(struct inode *ip, uint32_t ioctl_flags, xvattr_t *xva)
+ !capable(CAP_LINUX_IMMUTABLE))
+ return (-EACCES);
+
+- if (!inode_owner_or_capable(ip))
++ if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+ return (-EACCES);
+
+ xva_init(xva);
+diff --git a/module/os/linux/zfs/zpl_inode.c b/module/os/linux/zfs/zpl_inode.c
+index 117963f44af..cf0eab3e8c9 100644
+--- a/module/os/linux/zfs/zpl_inode.c
++++ b/module/os/linux/zfs/zpl_inode.c
+@@ -128,7 +128,12 @@ zpl_vap_init(vattr_t *vap, struct inode *dir, umode_t mode, cred_t *cr)
+ }
+
+ static int
++#ifdef HAVE_IOPS_CREATE_USERNS
++zpl_create(struct user_namespace *user_ns, struct inode *dir,
++ struct dentry *dentry, umode_t mode, bool flag)
++#else
+ zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
++#endif
+ {
+ cred_t *cr = CRED();
+ znode_t *zp;
+@@ -163,7 +168,12 @@ zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
+ }
+
+ static int
++#ifdef HAVE_IOPS_MKNOD_USERNS
++zpl_mknod(struct user_namespace *user_ns, struct inode *dir,
++ struct dentry *dentry, umode_t mode,
++#else
+ zpl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
++#endif
+ dev_t rdev)
+ {
+ cred_t *cr = CRED();
+@@ -278,7 +288,12 @@ zpl_unlink(struct inode *dir, struct dentry *dentry)
+ }
+
+ static int
++#ifdef HAVE_IOPS_MKDIR_USERNS
++zpl_mkdir(struct user_namespace *user_ns, struct inode *dir,
++ struct dentry *dentry, umode_t mode)
++#else
+ zpl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
++#endif
+ {
+ cred_t *cr = CRED();
+ vattr_t *vap;
+@@ -338,8 +353,14 @@ zpl_rmdir(struct inode *dir, struct dentry *dentry)
+ }
+
+ static int
++#ifdef HAVE_USERNS_IOPS_GETATTR
++zpl_getattr_impl(struct user_namespace *user_ns,
++ const struct path *path, struct kstat *stat, u32 request_mask,
++ unsigned int query_flags)
++#else
+ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
+ unsigned int query_flags)
++#endif
+ {
+ int error;
+ fstrans_cookie_t cookie;
+@@ -350,7 +371,11 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
+ * XXX request_mask and query_flags currently ignored.
+ */
+
+- error = -zfs_getattr_fast(path->dentry->d_inode, stat);
++#ifdef HAVE_USERNS_IOPS_GETATTR
++ error = -zfs_getattr_fast(user_ns, path->dentry->d_inode, stat);
++#else
++ error = -zfs_getattr_fast(kcred->user_ns, path->dentry->d_inode, stat);
++#endif
+ spl_fstrans_unmark(cookie);
+ ASSERT3S(error, <=, 0);
+
+@@ -359,7 +384,12 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
+ ZPL_GETATTR_WRAPPER(zpl_getattr);
+
+ static int
++#ifdef HAVE_SETATTR_PREPARE_USERNS
++zpl_setattr(struct user_namespace *user_ns, struct dentry *dentry,
++ struct iattr *ia)
++#else
+ zpl_setattr(struct dentry *dentry, struct iattr *ia)
++#endif
+ {
+ struct inode *ip = dentry->d_inode;
+ cred_t *cr = CRED();
+@@ -367,7 +397,7 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
+ int error;
+ fstrans_cookie_t cookie;
+
+- error = setattr_prepare(dentry, ia);
++ error = zpl_setattr_prepare(kcred->user_ns, dentry, ia);
+ if (error)
+ return (error);
+
+@@ -399,8 +429,14 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
+ }
+
+ static int
++#ifdef HAVE_IOPS_RENAME_USERNS
++zpl_rename2(struct user_namespace *user_ns, struct inode *sdip,
++ struct dentry *sdentry, struct inode *tdip, struct dentry *tdentry,
++ unsigned int flags)
++#else
+ zpl_rename2(struct inode *sdip, struct dentry *sdentry,
+ struct inode *tdip, struct dentry *tdentry, unsigned int flags)
++#endif
+ {
+ cred_t *cr = CRED();
+ int error;
+@@ -421,7 +457,7 @@ zpl_rename2(struct inode *sdip, struct dentry *sdentry,
+ return (error);
+ }
+
+-#ifndef HAVE_RENAME_WANTS_FLAGS
++#if !defined(HAVE_RENAME_WANTS_FLAGS) && !defined(HAVE_IOPS_RENAME_USERNS)
+ static int
+ zpl_rename(struct inode *sdip, struct dentry *sdentry,
+ struct inode *tdip, struct dentry *tdentry)
+@@ -431,7 +467,12 @@ zpl_rename(struct inode *sdip, struct dentry *sdentry,
+ #endif
+
+ static int
++#ifdef HAVE_IOPS_SYMLINK_USERNS
++zpl_symlink(struct user_namespace *user_ns, struct inode *dir,
++ struct dentry *dentry, const char *name)
++#else
+ zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name)
++#endif
+ {
+ cred_t *cr = CRED();
+ vattr_t *vap;
+@@ -678,7 +719,7 @@ const struct inode_operations zpl_dir_inode_operations = {
+ .mkdir = zpl_mkdir,
+ .rmdir = zpl_rmdir,
+ .mknod = zpl_mknod,
+-#ifdef HAVE_RENAME_WANTS_FLAGS
++#if defined(HAVE_RENAME_WANTS_FLAGS) || defined(HAVE_IOPS_RENAME_USERNS)
+ .rename = zpl_rename2,
+ #else
+ .rename = zpl_rename,
+diff --git a/module/os/linux/zfs/zpl_xattr.c b/module/os/linux/zfs/zpl_xattr.c
+index 83812f2dcba..971cd6ad031 100644
+--- a/module/os/linux/zfs/zpl_xattr.c
++++ b/module/os/linux/zfs/zpl_xattr.c
+@@ -1233,7 +1233,7 @@ __zpl_xattr_acl_set_access(struct inode *ip, const char *name,
+ if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIX)
+ return (-EOPNOTSUPP);
+
+- if (!inode_owner_or_capable(ip))
++ if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+ return (-EPERM);
+
+ if (value) {
+@@ -1273,7 +1273,7 @@ __zpl_xattr_acl_set_default(struct inode *ip, const char *name,
+ if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIX)
+ return (-EOPNOTSUPP);
+
+- if (!inode_owner_or_capable(ip))
++ if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+ return (-EPERM);
+
+ if (value) {
+From ffd6978ef59cfe2773e984bf03de2f0b93b03f5c Mon Sep 17 00:00:00 2001
+From: Coleman Kane <ckane@colemankane.org>
+Date: Sat, 20 Mar 2021 01:33:42 -0400
+Subject: [PATCH] Linux 5.12 update: bio_max_segs() replaces BIO_MAX_PAGES
+
+The BIO_MAX_PAGES macro is being retired in favor of a bio_max_segs()
+function that implements the typical MIN(x,y) logic used throughout the
+kernel for bounding the allocation, and also the new implementation is
+intended to be signed-safe (which the former was not).
+
+Reviewed-by: Tony Hutter <hutter2@llnl.gov>
+Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
+Signed-off-by: Coleman Kane <ckane@colemankane.org>
+Closes #11765
+---
+ config/kernel-bio_max_segs.m4 | 23 +++++++++++++++++++++++
+ config/kernel.m4 | 2 ++
+ module/os/linux/zfs/vdev_disk.c | 5 +++++
+ 3 files changed, 30 insertions(+)
+ create mode 100644 config/kernel-bio_max_segs.m4
+
+diff --git a/config/kernel-bio_max_segs.m4 b/config/kernel-bio_max_segs.m4
+new file mode 100644
+index 00000000000..a90d75455c1
+--- /dev/null
++++ b/config/kernel-bio_max_segs.m4
+@@ -0,0 +1,23 @@
++dnl #
++dnl # 5.12 API change removes BIO_MAX_PAGES in favor of bio_max_segs()
++dnl # which will handle the logic of setting the upper-bound to a
++dnl # BIO_MAX_PAGES, internally.
++dnl #
++AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS], [
++ ZFS_LINUX_TEST_SRC([bio_max_segs], [
++ #include <linux/bio.h>
++ ],[
++ bio_max_segs(1);
++ ])
++])
++
++AC_DEFUN([ZFS_AC_KERNEL_BIO_MAX_SEGS], [
++ AC_MSG_CHECKING([whether bio_max_segs() exists])
++ ZFS_LINUX_TEST_RESULT([bio_max_segs], [
++ AC_MSG_RESULT(yes)
++
++ AC_DEFINE([HAVE_BIO_MAX_SEGS], 1, [bio_max_segs() is implemented])
++ ],[
++ AC_MSG_RESULT(no)
++ ])
++])
+diff --git a/config/kernel.m4 b/config/kernel.m4
+index 24db38f09f4..dfb6165d879 100644
+--- a/config/kernel.m4
++++ b/config/kernel.m4
+@@ -128,6 +128,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
+ ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS
+ ZFS_AC_KERNEL_SRC_MKNOD
+ ZFS_AC_KERNEL_SRC_SYMLINK
++ ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS
+
+ AC_MSG_CHECKING([for available kernel interfaces])
+ ZFS_LINUX_TEST_COMPILE_ALL([kabi])
+@@ -229,6 +230,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
+ ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS
+ ZFS_AC_KERNEL_MKNOD
+ ZFS_AC_KERNEL_SYMLINK
++ ZFS_AC_KERNEL_BIO_MAX_SEGS
+ ])
+
+ dnl #
+diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c
+index ff71ef4cd06..c56fd3a6ff2 100644
+--- a/module/os/linux/zfs/vdev_disk.c
++++ b/module/os/linux/zfs/vdev_disk.c
+@@ -589,9 +589,14 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio,
+ }
+
+ /* bio_alloc() with __GFP_WAIT never returns NULL */
++#ifdef HAVE_BIO_MAX_SEGS
++ dr->dr_bio[i] = bio_alloc(GFP_NOIO, bio_max_segs(
++ abd_nr_pages_off(zio->io_abd, bio_size, abd_offset)));
++#else
+ dr->dr_bio[i] = bio_alloc(GFP_NOIO,
+ MIN(abd_nr_pages_off(zio->io_abd, bio_size, abd_offset),
+ BIO_MAX_PAGES));
++#endif
+ if (unlikely(dr->dr_bio[i] == NULL)) {
+ vdev_disk_dio_free(dr);
+ return (SET_ERROR(ENOMEM));
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