]>
Commit | Line | Data |
---|---|---|
68184a5a JR |
1 | From 7dd7dc8ba5f16e494206477d3880b7ed09aff118 Mon Sep 17 00:00:00 2001 |
2 | From: Miklos Szeredi <mszeredi@suse.cz> | |
3 | Date: Thu, 30 Aug 2012 16:13:49 +0200 | |
4 | Subject: [PATCH 04/13] overlay filesystem | |
5 | Patch-mainline: not yet | |
6 | ||
7 | Overlayfs allows one, usually read-write, directory tree to be | |
8 | overlaid onto another, read-only directory tree. All modifications | |
9 | go to the upper, writable layer. | |
10 | ||
11 | This type of mechanism is most often used for live CDs but there's a | |
12 | wide variety of other uses. | |
13 | ||
14 | The implementation differs from other "union filesystem" | |
15 | implementations in that after a file is opened all operations go | |
16 | directly to the underlying, lower or upper, filesystems. This | |
17 | simplifies the implementation and allows native performance in these | |
18 | cases. | |
19 | ||
20 | The dentry tree is duplicated from the underlying filesystems, this | |
21 | enables fast cached lookups without adding special support into the | |
22 | VFS. This uses slightly more memory than union mounts, but dentries | |
23 | are relatively small. | |
24 | ||
25 | Currently inodes are duplicated as well, but it is a possible | |
26 | optimization to share inodes for non-directories. | |
27 | ||
28 | Opening non directories results in the open forwarded to the | |
29 | underlying filesystem. This makes the behavior very similar to union | |
30 | mounts (with the same limitations vs. fchmod/fchown on O_RDONLY file | |
31 | descriptors). | |
32 | ||
c06a8ce3 | 33 | Usage: |
68184a5a JR |
34 | |
35 | mount -t overlay -olowerdir=/lower,upperdir=/upper overlay /mnt | |
36 | ||
c06a8ce3 | 37 | Supported: |
68184a5a JR |
38 | |
39 | - all operations | |
40 | ||
c06a8ce3 | 41 | Missing: |
68184a5a JR |
42 | |
43 | - Currently a crash in the middle of copy-up, rename, unlink, rmdir or create | |
44 | over a whiteout may result in filesystem corruption on the overlay level. | |
45 | IOW these operations need to become atomic or at least the corruption needs | |
46 | to be detected. | |
47 | ||
48 | ||
49 | The following cotributions have been folded into this patch: | |
50 | ||
51 | Neil Brown <neilb@suse.de>: | |
52 | - minimal remount support | |
53 | - use correct seek function for directories | |
54 | - initialise is_real before use | |
55 | - rename ovl_fill_cache to ovl_dir_read | |
56 | ||
57 | Felix Fietkau <nbd@openwrt.org>: | |
58 | - fix a deadlock in ovl_dir_read_merged | |
59 | - fix a deadlock in ovl_remove_whiteouts | |
60 | ||
61 | Erez Zadok <ezk@fsl.cs.sunysb.edu> | |
62 | - fix cleanup after WARN_ON | |
63 | ||
64 | Sedat Dilek <sedat.dilek@googlemail.com> | |
65 | - fix up permission to confirm to new API | |
66 | ||
c06a8ce3 AM |
67 | Robin Dong <hao.bigrat@gmail.com> |
68 | - fix possible leak in ovl_new_inode | |
69 | - create new inode in ovl_link | |
70 | ||
71 | Andy Whitcroft <apw@canonical.com> | |
72 | - switch to __inode_permission() | |
73 | - copy up i_uid/i_gid from the underlying inode | |
74 | ||
68184a5a JR |
75 | Also thanks to the following people for testing and reporting bugs: |
76 | ||
77 | Jordi Pujol <jordipujolp@gmail.com> | |
78 | Andy Whitcroft <apw@canonical.com> | |
79 | Michal Suchanek <hramrach@centrum.cz> | |
80 | Felix Fietkau <nbd@openwrt.org> | |
81 | Erez Zadok <ezk@fsl.cs.sunysb.edu> | |
82 | Randy Dunlap <rdunlap@xenotime.net> | |
83 | ||
84 | Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> | |
85 | --- | |
86 | fs/Kconfig | 1 | |
87 | fs/Makefile | 1 | |
c06a8ce3 | 88 | fs/overlayfs/Kconfig | 10 |
68184a5a | 89 | fs/overlayfs/Makefile | 7 |
392086de | 90 | fs/overlayfs/copy_up.c | 388 +++++++++++++++++++++++++++++ |
c06a8ce3 AM |
91 | fs/overlayfs/dir.c | 605 ++++++++++++++++++++++++++++++++++++++++++++++ |
92 | fs/overlayfs/inode.c | 372 ++++++++++++++++++++++++++++ | |
93 | fs/overlayfs/overlayfs.h | 70 +++++ | |
392086de | 94 | fs/overlayfs/readdir.c | 567 +++++++++++++++++++++++++++++++++++++++++++ |
c06a8ce3 | 95 | fs/overlayfs/super.c | 612 +++++++++++++++++++++++++++++++++++++++++++++++ |
392086de | 96 | 10 files changed, 2633 insertions(+) |
68184a5a | 97 | |
514e5dae AM |
98 | --- a/fs/Kconfig |
99 | +++ b/fs/Kconfig | |
392086de | 100 | @@ -67,6 +67,7 @@ source "fs/quota/Kconfig" |
68184a5a JR |
101 | |
102 | source "fs/autofs4/Kconfig" | |
103 | source "fs/fuse/Kconfig" | |
104 | +source "fs/overlayfs/Kconfig" | |
105 | ||
24aef795 JR |
106 | menu "Caches" |
107 | ||
514e5dae AM |
108 | --- a/fs/Makefile |
109 | +++ b/fs/Makefile | |
392086de | 110 | @@ -105,6 +105,7 @@ obj-$(CONFIG_QNX6FS_FS) += qnx6/ |
68184a5a JR |
111 | obj-$(CONFIG_AUTOFS4_FS) += autofs4/ |
112 | obj-$(CONFIG_ADFS_FS) += adfs/ | |
113 | obj-$(CONFIG_FUSE_FS) += fuse/ | |
114 | +obj-$(CONFIG_OVERLAYFS_FS) += overlayfs/ | |
115 | obj-$(CONFIG_UDF_FS) += udf/ | |
116 | obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/ | |
117 | obj-$(CONFIG_OMFS_FS) += omfs/ | |
514e5dae AM |
118 | --- /dev/null |
119 | +++ b/fs/overlayfs/Kconfig | |
c06a8ce3 | 120 | @@ -0,0 +1,10 @@ |
68184a5a JR |
121 | +config OVERLAYFS_FS |
122 | + tristate "Overlay filesystem support" | |
123 | + help | |
c06a8ce3 AM |
124 | + An overlay filesystem combines two filesystems - an 'upper' filesystem |
125 | + and a 'lower' filesystem. When a name exists in both filesystems, the | |
126 | + object in the 'upper' filesystem is visible while the object in the | |
127 | + 'lower' filesystem is either hidden or, in the case of directories, | |
128 | + merged with the 'upper' object. | |
129 | + | |
130 | + For more information see Documentation/filesystems/overlayfs.txt | |
514e5dae AM |
131 | --- /dev/null |
132 | +++ b/fs/overlayfs/Makefile | |
68184a5a JR |
133 | @@ -0,0 +1,7 @@ |
134 | +# | |
135 | +# Makefile for the overlay filesystem. | |
136 | +# | |
137 | + | |
138 | +obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o | |
139 | + | |
140 | +overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o | |
514e5dae AM |
141 | --- /dev/null |
142 | +++ b/fs/overlayfs/copy_up.c | |
392086de | 143 | @@ -0,0 +1,388 @@ |
68184a5a JR |
144 | +/* |
145 | + * | |
146 | + * Copyright (C) 2011 Novell Inc. | |
147 | + * | |
148 | + * This program is free software; you can redistribute it and/or modify it | |
149 | + * under the terms of the GNU General Public License version 2 as published by | |
150 | + * the Free Software Foundation. | |
151 | + */ | |
152 | + | |
153 | +#include <linux/fs.h> | |
154 | +#include <linux/slab.h> | |
155 | +#include <linux/file.h> | |
156 | +#include <linux/splice.h> | |
157 | +#include <linux/xattr.h> | |
158 | +#include <linux/security.h> | |
159 | +#include <linux/uaccess.h> | |
160 | +#include <linux/sched.h> | |
161 | +#include "overlayfs.h" | |
162 | + | |
163 | +#define OVL_COPY_UP_CHUNK_SIZE (1 << 20) | |
164 | + | |
165 | +static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new) | |
166 | +{ | |
167 | + ssize_t list_size, size; | |
168 | + char *buf, *name, *value; | |
169 | + int error; | |
170 | + | |
171 | + if (!old->d_inode->i_op->getxattr || | |
172 | + !new->d_inode->i_op->getxattr) | |
173 | + return 0; | |
174 | + | |
175 | + list_size = vfs_listxattr(old, NULL, 0); | |
176 | + if (list_size <= 0) { | |
177 | + if (list_size == -EOPNOTSUPP) | |
178 | + return 0; | |
179 | + return list_size; | |
180 | + } | |
181 | + | |
182 | + buf = kzalloc(list_size, GFP_KERNEL); | |
183 | + if (!buf) | |
184 | + return -ENOMEM; | |
185 | + | |
186 | + error = -ENOMEM; | |
187 | + value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL); | |
188 | + if (!value) | |
189 | + goto out; | |
190 | + | |
191 | + list_size = vfs_listxattr(old, buf, list_size); | |
192 | + if (list_size <= 0) { | |
193 | + error = list_size; | |
194 | + goto out_free_value; | |
195 | + } | |
196 | + | |
197 | + for (name = buf; name < (buf + list_size); name += strlen(name) + 1) { | |
198 | + size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX); | |
199 | + if (size <= 0) { | |
200 | + error = size; | |
201 | + goto out_free_value; | |
202 | + } | |
203 | + error = vfs_setxattr(new, name, value, size, 0); | |
204 | + if (error) | |
205 | + goto out_free_value; | |
206 | + } | |
207 | + | |
208 | +out_free_value: | |
209 | + kfree(value); | |
210 | +out: | |
211 | + kfree(buf); | |
212 | + return error; | |
213 | +} | |
214 | + | |
215 | +static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) | |
216 | +{ | |
217 | + struct file *old_file; | |
218 | + struct file *new_file; | |
c06a8ce3 AM |
219 | + loff_t old_pos = 0; |
220 | + loff_t new_pos = 0; | |
68184a5a JR |
221 | + int error = 0; |
222 | + | |
223 | + if (len == 0) | |
224 | + return 0; | |
225 | + | |
226 | + old_file = ovl_path_open(old, O_RDONLY); | |
227 | + if (IS_ERR(old_file)) | |
228 | + return PTR_ERR(old_file); | |
229 | + | |
230 | + new_file = ovl_path_open(new, O_WRONLY); | |
231 | + if (IS_ERR(new_file)) { | |
232 | + error = PTR_ERR(new_file); | |
233 | + goto out_fput; | |
234 | + } | |
235 | + | |
236 | + /* FIXME: copy up sparse files efficiently */ | |
237 | + while (len) { | |
68184a5a JR |
238 | + size_t this_len = OVL_COPY_UP_CHUNK_SIZE; |
239 | + long bytes; | |
240 | + | |
241 | + if (len < this_len) | |
242 | + this_len = len; | |
243 | + | |
244 | + if (signal_pending_state(TASK_KILLABLE, current)) { | |
245 | + error = -EINTR; | |
246 | + break; | |
247 | + } | |
248 | + | |
c06a8ce3 AM |
249 | + bytes = do_splice_direct(old_file, &old_pos, |
250 | + new_file, &new_pos, | |
251 | + this_len, SPLICE_F_MOVE); | |
68184a5a JR |
252 | + if (bytes <= 0) { |
253 | + error = bytes; | |
254 | + break; | |
255 | + } | |
392086de | 256 | + WARN_ON(old_pos != new_pos); |
68184a5a JR |
257 | + |
258 | + len -= bytes; | |
259 | + } | |
260 | + | |
261 | + fput(new_file); | |
262 | +out_fput: | |
263 | + fput(old_file); | |
264 | + return error; | |
265 | +} | |
266 | + | |
267 | +static char *ovl_read_symlink(struct dentry *realdentry) | |
268 | +{ | |
269 | + int res; | |
270 | + char *buf; | |
271 | + struct inode *inode = realdentry->d_inode; | |
272 | + mm_segment_t old_fs; | |
273 | + | |
274 | + res = -EINVAL; | |
275 | + if (!inode->i_op->readlink) | |
276 | + goto err; | |
277 | + | |
278 | + res = -ENOMEM; | |
279 | + buf = (char *) __get_free_page(GFP_KERNEL); | |
280 | + if (!buf) | |
281 | + goto err; | |
282 | + | |
283 | + old_fs = get_fs(); | |
284 | + set_fs(get_ds()); | |
285 | + /* The cast to a user pointer is valid due to the set_fs() */ | |
286 | + res = inode->i_op->readlink(realdentry, | |
287 | + (char __user *)buf, PAGE_SIZE - 1); | |
288 | + set_fs(old_fs); | |
289 | + if (res < 0) { | |
290 | + free_page((unsigned long) buf); | |
291 | + goto err; | |
292 | + } | |
293 | + buf[res] = '\0'; | |
294 | + | |
295 | + return buf; | |
296 | + | |
297 | +err: | |
298 | + return ERR_PTR(res); | |
299 | +} | |
300 | + | |
301 | +static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) | |
302 | +{ | |
303 | + struct iattr attr = { | |
304 | + .ia_valid = | |
305 | + ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET, | |
306 | + .ia_atime = stat->atime, | |
307 | + .ia_mtime = stat->mtime, | |
308 | + }; | |
309 | + | |
a25ec4e9 | 310 | + return notify_change(upperdentry, &attr, NULL); |
68184a5a JR |
311 | +} |
312 | + | |
313 | +static int ovl_set_mode(struct dentry *upperdentry, umode_t mode) | |
314 | +{ | |
315 | + struct iattr attr = { | |
316 | + .ia_valid = ATTR_MODE, | |
317 | + .ia_mode = mode, | |
318 | + }; | |
319 | + | |
a25ec4e9 | 320 | + return notify_change(upperdentry, &attr, NULL); |
68184a5a JR |
321 | +} |
322 | + | |
323 | +static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry, | |
324 | + struct path *lowerpath, struct kstat *stat, | |
325 | + const char *link) | |
326 | +{ | |
327 | + int err; | |
328 | + struct path newpath; | |
329 | + umode_t mode = stat->mode; | |
330 | + | |
331 | + /* Can't properly set mode on creation because of the umask */ | |
332 | + stat->mode &= S_IFMT; | |
333 | + | |
334 | + ovl_path_upper(dentry, &newpath); | |
335 | + WARN_ON(newpath.dentry); | |
336 | + newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link); | |
337 | + if (IS_ERR(newpath.dentry)) | |
338 | + return PTR_ERR(newpath.dentry); | |
339 | + | |
340 | + if (S_ISREG(stat->mode)) { | |
341 | + err = ovl_copy_up_data(lowerpath, &newpath, stat->size); | |
342 | + if (err) | |
343 | + goto err_remove; | |
344 | + } | |
345 | + | |
346 | + err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry); | |
347 | + if (err) | |
348 | + goto err_remove; | |
349 | + | |
350 | + mutex_lock(&newpath.dentry->d_inode->i_mutex); | |
351 | + if (!S_ISLNK(stat->mode)) | |
352 | + err = ovl_set_mode(newpath.dentry, mode); | |
353 | + if (!err) | |
354 | + err = ovl_set_timestamps(newpath.dentry, stat); | |
355 | + mutex_unlock(&newpath.dentry->d_inode->i_mutex); | |
356 | + if (err) | |
357 | + goto err_remove; | |
358 | + | |
359 | + ovl_dentry_update(dentry, newpath.dentry); | |
360 | + | |
361 | + /* | |
362 | + * Easiest way to get rid of the lower dentry reference is to | |
363 | + * drop this dentry. This is neither needed nor possible for | |
364 | + * directories. | |
365 | + */ | |
366 | + if (!S_ISDIR(stat->mode)) | |
367 | + d_drop(dentry); | |
368 | + | |
369 | + return 0; | |
370 | + | |
371 | +err_remove: | |
372 | + if (S_ISDIR(stat->mode)) | |
373 | + vfs_rmdir(upperdir->d_inode, newpath.dentry); | |
374 | + else | |
a25ec4e9 | 375 | + vfs_unlink(upperdir->d_inode, newpath.dentry, NULL); |
68184a5a JR |
376 | + |
377 | + dput(newpath.dentry); | |
378 | + | |
379 | + return err; | |
380 | +} | |
381 | + | |
382 | +/* | |
383 | + * Copy up a single dentry | |
384 | + * | |
385 | + * Directory renames only allowed on "pure upper" (already created on | |
386 | + * upper filesystem, never copied up). Directories which are on lower or | |
387 | + * are merged may not be renamed. For these -EXDEV is returned and | |
388 | + * userspace has to deal with it. This means, when copying up a | |
389 | + * directory we can rely on it and ancestors being stable. | |
390 | + * | |
391 | + * Non-directory renames start with copy up of source if necessary. The | |
392 | + * actual rename will only proceed once the copy up was successful. Copy | |
393 | + * up uses upper parent i_mutex for exclusion. Since rename can change | |
394 | + * d_parent it is possible that the copy up will lock the old parent. At | |
395 | + * that point the file will have already been copied up anyway. | |
396 | + */ | |
397 | +static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, | |
398 | + struct path *lowerpath, struct kstat *stat) | |
399 | +{ | |
400 | + int err; | |
401 | + struct kstat pstat; | |
402 | + struct path parentpath; | |
403 | + struct dentry *upperdir; | |
404 | + const struct cred *old_cred; | |
405 | + struct cred *override_cred; | |
406 | + char *link = NULL; | |
407 | + | |
408 | + ovl_path_upper(parent, &parentpath); | |
409 | + upperdir = parentpath.dentry; | |
410 | + | |
514e5dae | 411 | + err = vfs_getattr(&parentpath, &pstat); |
68184a5a JR |
412 | + if (err) |
413 | + return err; | |
414 | + | |
415 | + if (S_ISLNK(stat->mode)) { | |
416 | + link = ovl_read_symlink(lowerpath->dentry); | |
417 | + if (IS_ERR(link)) | |
418 | + return PTR_ERR(link); | |
419 | + } | |
420 | + | |
421 | + err = -ENOMEM; | |
422 | + override_cred = prepare_creds(); | |
423 | + if (!override_cred) | |
424 | + goto out_free_link; | |
425 | + | |
426 | + override_cred->fsuid = stat->uid; | |
427 | + override_cred->fsgid = stat->gid; | |
428 | + /* | |
429 | + * CAP_SYS_ADMIN for copying up extended attributes | |
430 | + * CAP_DAC_OVERRIDE for create | |
431 | + * CAP_FOWNER for chmod, timestamp update | |
432 | + * CAP_FSETID for chmod | |
433 | + * CAP_MKNOD for mknod | |
434 | + */ | |
435 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
436 | + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
437 | + cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
438 | + cap_raise(override_cred->cap_effective, CAP_FSETID); | |
439 | + cap_raise(override_cred->cap_effective, CAP_MKNOD); | |
440 | + old_cred = override_creds(override_cred); | |
441 | + | |
442 | + mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); | |
443 | + if (ovl_path_type(dentry) != OVL_PATH_LOWER) { | |
444 | + err = 0; | |
445 | + } else { | |
446 | + err = ovl_copy_up_locked(upperdir, dentry, lowerpath, | |
447 | + stat, link); | |
448 | + if (!err) { | |
449 | + /* Restore timestamps on parent (best effort) */ | |
450 | + ovl_set_timestamps(upperdir, &pstat); | |
451 | + } | |
452 | + } | |
453 | + | |
454 | + mutex_unlock(&upperdir->d_inode->i_mutex); | |
455 | + | |
456 | + revert_creds(old_cred); | |
457 | + put_cred(override_cred); | |
458 | + | |
459 | +out_free_link: | |
460 | + if (link) | |
461 | + free_page((unsigned long) link); | |
462 | + | |
463 | + return err; | |
464 | +} | |
465 | + | |
466 | +int ovl_copy_up(struct dentry *dentry) | |
467 | +{ | |
468 | + int err; | |
469 | + | |
470 | + err = 0; | |
471 | + while (!err) { | |
472 | + struct dentry *next; | |
473 | + struct dentry *parent; | |
474 | + struct path lowerpath; | |
475 | + struct kstat stat; | |
476 | + enum ovl_path_type type = ovl_path_type(dentry); | |
477 | + | |
478 | + if (type != OVL_PATH_LOWER) | |
479 | + break; | |
480 | + | |
481 | + next = dget(dentry); | |
482 | + /* find the topmost dentry not yet copied up */ | |
483 | + for (;;) { | |
484 | + parent = dget_parent(next); | |
485 | + | |
486 | + type = ovl_path_type(parent); | |
487 | + if (type != OVL_PATH_LOWER) | |
488 | + break; | |
489 | + | |
490 | + dput(next); | |
491 | + next = parent; | |
492 | + } | |
493 | + | |
494 | + ovl_path_lower(next, &lowerpath); | |
514e5dae | 495 | + err = vfs_getattr(&lowerpath, &stat); |
68184a5a JR |
496 | + if (!err) |
497 | + err = ovl_copy_up_one(parent, next, &lowerpath, &stat); | |
498 | + | |
499 | + dput(parent); | |
500 | + dput(next); | |
501 | + } | |
502 | + | |
503 | + return err; | |
504 | +} | |
505 | + | |
506 | +/* Optimize by not copying up the file first and truncating later */ | |
507 | +int ovl_copy_up_truncate(struct dentry *dentry, loff_t size) | |
508 | +{ | |
509 | + int err; | |
510 | + struct kstat stat; | |
511 | + struct path lowerpath; | |
512 | + struct dentry *parent = dget_parent(dentry); | |
513 | + | |
514 | + err = ovl_copy_up(parent); | |
515 | + if (err) | |
516 | + goto out_dput_parent; | |
517 | + | |
518 | + ovl_path_lower(dentry, &lowerpath); | |
514e5dae | 519 | + err = vfs_getattr(&lowerpath, &stat); |
68184a5a JR |
520 | + if (err) |
521 | + goto out_dput_parent; | |
522 | + | |
523 | + if (size < stat.size) | |
524 | + stat.size = size; | |
525 | + | |
526 | + err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat); | |
527 | + | |
528 | +out_dput_parent: | |
529 | + dput(parent); | |
530 | + return err; | |
531 | +} | |
514e5dae AM |
532 | --- /dev/null |
533 | +++ b/fs/overlayfs/dir.c | |
a25ec4e9 | 534 | @@ -0,0 +1,606 @@ |
68184a5a JR |
535 | +/* |
536 | + * | |
537 | + * Copyright (C) 2011 Novell Inc. | |
538 | + * | |
539 | + * This program is free software; you can redistribute it and/or modify it | |
540 | + * under the terms of the GNU General Public License version 2 as published by | |
541 | + * the Free Software Foundation. | |
542 | + */ | |
543 | + | |
544 | +#include <linux/fs.h> | |
545 | +#include <linux/namei.h> | |
546 | +#include <linux/xattr.h> | |
547 | +#include <linux/security.h> | |
548 | +#include <linux/cred.h> | |
549 | +#include "overlayfs.h" | |
550 | + | |
551 | +static const char *ovl_whiteout_symlink = "(overlay-whiteout)"; | |
552 | + | |
553 | +static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry) | |
554 | +{ | |
555 | + int err; | |
556 | + struct dentry *newdentry; | |
557 | + const struct cred *old_cred; | |
558 | + struct cred *override_cred; | |
559 | + | |
560 | + /* FIXME: recheck lower dentry to see if whiteout is really needed */ | |
561 | + | |
562 | + err = -ENOMEM; | |
563 | + override_cred = prepare_creds(); | |
564 | + if (!override_cred) | |
565 | + goto out; | |
566 | + | |
567 | + /* | |
568 | + * CAP_SYS_ADMIN for setxattr | |
569 | + * CAP_DAC_OVERRIDE for symlink creation | |
570 | + * CAP_FOWNER for unlink in sticky directory | |
571 | + */ | |
572 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
573 | + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
574 | + cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
575 | + override_cred->fsuid = GLOBAL_ROOT_UID; | |
576 | + override_cred->fsgid = GLOBAL_ROOT_GID; | |
577 | + old_cred = override_creds(override_cred); | |
578 | + | |
579 | + newdentry = lookup_one_len(dentry->d_name.name, upperdir, | |
580 | + dentry->d_name.len); | |
581 | + err = PTR_ERR(newdentry); | |
582 | + if (IS_ERR(newdentry)) | |
583 | + goto out_put_cred; | |
584 | + | |
585 | + /* Just been removed within the same locked region */ | |
586 | + WARN_ON(newdentry->d_inode); | |
587 | + | |
588 | + err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink); | |
589 | + if (err) | |
590 | + goto out_dput; | |
591 | + | |
592 | + ovl_dentry_version_inc(dentry->d_parent); | |
593 | + | |
594 | + err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0); | |
595 | + if (err) | |
a25ec4e9 | 596 | + vfs_unlink(upperdir->d_inode, newdentry, NULL); |
68184a5a JR |
597 | + |
598 | +out_dput: | |
599 | + dput(newdentry); | |
600 | +out_put_cred: | |
601 | + revert_creds(old_cred); | |
602 | + put_cred(override_cred); | |
603 | +out: | |
604 | + if (err) { | |
605 | + /* | |
606 | + * There's no way to recover from failure to whiteout. | |
607 | + * What should we do? Log a big fat error and... ? | |
608 | + */ | |
c06a8ce3 | 609 | + pr_err("overlayfs: ERROR - failed to whiteout '%s'\n", |
68184a5a JR |
610 | + dentry->d_name.name); |
611 | + } | |
612 | + | |
613 | + return err; | |
614 | +} | |
615 | + | |
616 | +static struct dentry *ovl_lookup_create(struct dentry *upperdir, | |
617 | + struct dentry *template) | |
618 | +{ | |
619 | + int err; | |
620 | + struct dentry *newdentry; | |
621 | + struct qstr *name = &template->d_name; | |
622 | + | |
623 | + newdentry = lookup_one_len(name->name, upperdir, name->len); | |
624 | + if (IS_ERR(newdentry)) | |
625 | + return newdentry; | |
626 | + | |
627 | + if (newdentry->d_inode) { | |
628 | + const struct cred *old_cred; | |
629 | + struct cred *override_cred; | |
630 | + | |
631 | + /* No need to check whiteout if lower parent is non-existent */ | |
632 | + err = -EEXIST; | |
633 | + if (!ovl_dentry_lower(template->d_parent)) | |
634 | + goto out_dput; | |
635 | + | |
636 | + if (!S_ISLNK(newdentry->d_inode->i_mode)) | |
637 | + goto out_dput; | |
638 | + | |
639 | + err = -ENOMEM; | |
640 | + override_cred = prepare_creds(); | |
641 | + if (!override_cred) | |
642 | + goto out_dput; | |
643 | + | |
644 | + /* | |
645 | + * CAP_SYS_ADMIN for getxattr | |
646 | + * CAP_FOWNER for unlink in sticky directory | |
647 | + */ | |
648 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
649 | + cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
650 | + old_cred = override_creds(override_cred); | |
651 | + | |
652 | + err = -EEXIST; | |
653 | + if (ovl_is_whiteout(newdentry)) | |
a25ec4e9 | 654 | + err = vfs_unlink(upperdir->d_inode, newdentry, NULL); |
68184a5a JR |
655 | + |
656 | + revert_creds(old_cred); | |
657 | + put_cred(override_cred); | |
658 | + if (err) | |
659 | + goto out_dput; | |
660 | + | |
661 | + dput(newdentry); | |
662 | + newdentry = lookup_one_len(name->name, upperdir, name->len); | |
663 | + if (IS_ERR(newdentry)) { | |
664 | + ovl_whiteout(upperdir, template); | |
665 | + return newdentry; | |
666 | + } | |
667 | + | |
668 | + /* | |
669 | + * Whiteout just been successfully removed, parent | |
670 | + * i_mutex is still held, there's no way the lookup | |
671 | + * could return positive. | |
672 | + */ | |
673 | + WARN_ON(newdentry->d_inode); | |
674 | + } | |
675 | + | |
676 | + return newdentry; | |
677 | + | |
678 | +out_dput: | |
679 | + dput(newdentry); | |
680 | + return ERR_PTR(err); | |
681 | +} | |
682 | + | |
683 | +struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, | |
684 | + struct kstat *stat, const char *link) | |
685 | +{ | |
686 | + int err; | |
687 | + struct dentry *newdentry; | |
688 | + struct inode *dir = upperdir->d_inode; | |
689 | + | |
690 | + newdentry = ovl_lookup_create(upperdir, dentry); | |
691 | + if (IS_ERR(newdentry)) | |
692 | + goto out; | |
693 | + | |
694 | + switch (stat->mode & S_IFMT) { | |
695 | + case S_IFREG: | |
696 | + err = vfs_create(dir, newdentry, stat->mode, NULL); | |
697 | + break; | |
698 | + | |
699 | + case S_IFDIR: | |
700 | + err = vfs_mkdir(dir, newdentry, stat->mode); | |
701 | + break; | |
702 | + | |
703 | + case S_IFCHR: | |
704 | + case S_IFBLK: | |
705 | + case S_IFIFO: | |
706 | + case S_IFSOCK: | |
707 | + err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev); | |
708 | + break; | |
709 | + | |
710 | + case S_IFLNK: | |
711 | + err = vfs_symlink(dir, newdentry, link); | |
712 | + break; | |
713 | + | |
714 | + default: | |
715 | + err = -EPERM; | |
716 | + } | |
717 | + if (err) { | |
718 | + if (ovl_dentry_is_opaque(dentry)) | |
719 | + ovl_whiteout(upperdir, dentry); | |
720 | + dput(newdentry); | |
721 | + newdentry = ERR_PTR(err); | |
722 | + } else if (WARN_ON(!newdentry->d_inode)) { | |
723 | + /* | |
724 | + * Not quite sure if non-instantiated dentry is legal or not. | |
725 | + * VFS doesn't seem to care so check and warn here. | |
726 | + */ | |
727 | + dput(newdentry); | |
728 | + newdentry = ERR_PTR(-ENOENT); | |
729 | + } | |
730 | + | |
731 | +out: | |
732 | + return newdentry; | |
733 | + | |
734 | +} | |
735 | + | |
736 | +static int ovl_set_opaque(struct dentry *upperdentry) | |
737 | +{ | |
738 | + int err; | |
739 | + const struct cred *old_cred; | |
740 | + struct cred *override_cred; | |
741 | + | |
742 | + override_cred = prepare_creds(); | |
743 | + if (!override_cred) | |
744 | + return -ENOMEM; | |
745 | + | |
746 | + /* CAP_SYS_ADMIN for setxattr of "trusted" namespace */ | |
747 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
748 | + old_cred = override_creds(override_cred); | |
749 | + err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0); | |
750 | + revert_creds(old_cred); | |
751 | + put_cred(override_cred); | |
752 | + | |
753 | + return err; | |
754 | +} | |
755 | + | |
756 | +static int ovl_remove_opaque(struct dentry *upperdentry) | |
757 | +{ | |
758 | + int err; | |
759 | + const struct cred *old_cred; | |
760 | + struct cred *override_cred; | |
761 | + | |
762 | + override_cred = prepare_creds(); | |
763 | + if (!override_cred) | |
764 | + return -ENOMEM; | |
765 | + | |
766 | + /* CAP_SYS_ADMIN for removexattr of "trusted" namespace */ | |
767 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
768 | + old_cred = override_creds(override_cred); | |
769 | + err = vfs_removexattr(upperdentry, ovl_opaque_xattr); | |
770 | + revert_creds(old_cred); | |
771 | + put_cred(override_cred); | |
772 | + | |
773 | + return err; | |
774 | +} | |
775 | + | |
776 | +static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
777 | + struct kstat *stat) | |
778 | +{ | |
779 | + int err; | |
780 | + enum ovl_path_type type; | |
781 | + struct path realpath; | |
782 | + | |
783 | + type = ovl_path_real(dentry, &realpath); | |
514e5dae | 784 | + err = vfs_getattr(&realpath, stat); |
68184a5a JR |
785 | + if (err) |
786 | + return err; | |
787 | + | |
788 | + stat->dev = dentry->d_sb->s_dev; | |
789 | + stat->ino = dentry->d_inode->i_ino; | |
790 | + | |
791 | + /* | |
792 | + * It's probably not worth it to count subdirs to get the | |
793 | + * correct link count. nlink=1 seems to pacify 'find' and | |
794 | + * other utilities. | |
795 | + */ | |
796 | + if (type == OVL_PATH_MERGE) | |
797 | + stat->nlink = 1; | |
798 | + | |
799 | + return 0; | |
800 | +} | |
801 | + | |
802 | +static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, | |
803 | + const char *link) | |
804 | +{ | |
805 | + int err; | |
806 | + struct dentry *newdentry; | |
807 | + struct dentry *upperdir; | |
808 | + struct inode *inode; | |
809 | + struct kstat stat = { | |
810 | + .mode = mode, | |
811 | + .rdev = rdev, | |
812 | + }; | |
813 | + | |
814 | + err = -ENOMEM; | |
815 | + inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata); | |
816 | + if (!inode) | |
817 | + goto out; | |
818 | + | |
819 | + err = ovl_copy_up(dentry->d_parent); | |
820 | + if (err) | |
821 | + goto out_iput; | |
822 | + | |
823 | + upperdir = ovl_dentry_upper(dentry->d_parent); | |
824 | + mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); | |
825 | + | |
826 | + newdentry = ovl_upper_create(upperdir, dentry, &stat, link); | |
827 | + err = PTR_ERR(newdentry); | |
828 | + if (IS_ERR(newdentry)) | |
829 | + goto out_unlock; | |
830 | + | |
831 | + ovl_dentry_version_inc(dentry->d_parent); | |
832 | + if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) { | |
833 | + err = ovl_set_opaque(newdentry); | |
834 | + if (err) { | |
835 | + vfs_rmdir(upperdir->d_inode, newdentry); | |
836 | + ovl_whiteout(upperdir, dentry); | |
837 | + goto out_dput; | |
838 | + } | |
839 | + } | |
840 | + ovl_dentry_update(dentry, newdentry); | |
c06a8ce3 | 841 | + ovl_copyattr(newdentry->d_inode, inode); |
68184a5a JR |
842 | + d_instantiate(dentry, inode); |
843 | + inode = NULL; | |
844 | + newdentry = NULL; | |
845 | + err = 0; | |
846 | + | |
847 | +out_dput: | |
848 | + dput(newdentry); | |
849 | +out_unlock: | |
850 | + mutex_unlock(&upperdir->d_inode->i_mutex); | |
851 | +out_iput: | |
852 | + iput(inode); | |
853 | +out: | |
854 | + return err; | |
855 | +} | |
856 | + | |
857 | +static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode, | |
858 | + bool excl) | |
859 | +{ | |
860 | + return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); | |
861 | +} | |
862 | + | |
863 | +static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
864 | +{ | |
865 | + return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); | |
866 | +} | |
867 | + | |
868 | +static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, | |
869 | + dev_t rdev) | |
870 | +{ | |
871 | + return ovl_create_object(dentry, mode, rdev, NULL); | |
872 | +} | |
873 | + | |
874 | +static int ovl_symlink(struct inode *dir, struct dentry *dentry, | |
875 | + const char *link) | |
876 | +{ | |
877 | + return ovl_create_object(dentry, S_IFLNK, 0, link); | |
878 | +} | |
879 | + | |
880 | +static int ovl_do_remove(struct dentry *dentry, bool is_dir) | |
881 | +{ | |
882 | + int err; | |
883 | + enum ovl_path_type type; | |
884 | + struct path realpath; | |
885 | + struct dentry *upperdir; | |
886 | + | |
887 | + err = ovl_copy_up(dentry->d_parent); | |
888 | + if (err) | |
889 | + return err; | |
890 | + | |
891 | + upperdir = ovl_dentry_upper(dentry->d_parent); | |
892 | + mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); | |
893 | + type = ovl_path_real(dentry, &realpath); | |
894 | + if (type != OVL_PATH_LOWER) { | |
895 | + err = -ESTALE; | |
896 | + if (realpath.dentry->d_parent != upperdir) | |
897 | + goto out_d_drop; | |
898 | + | |
899 | + /* FIXME: create whiteout up front and rename to target */ | |
900 | + | |
901 | + if (is_dir) | |
902 | + err = vfs_rmdir(upperdir->d_inode, realpath.dentry); | |
903 | + else | |
a25ec4e9 AM |
904 | + err = vfs_unlink(upperdir->d_inode, realpath.dentry, |
905 | + NULL); | |
68184a5a JR |
906 | + if (err) |
907 | + goto out_d_drop; | |
908 | + | |
909 | + ovl_dentry_version_inc(dentry->d_parent); | |
910 | + } | |
911 | + | |
912 | + if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry)) | |
913 | + err = ovl_whiteout(upperdir, dentry); | |
914 | + | |
915 | + /* | |
916 | + * Keeping this dentry hashed would mean having to release | |
917 | + * upperpath/lowerpath, which could only be done if we are the | |
918 | + * sole user of this dentry. Too tricky... Just unhash for | |
919 | + * now. | |
920 | + */ | |
921 | +out_d_drop: | |
922 | + d_drop(dentry); | |
923 | + mutex_unlock(&upperdir->d_inode->i_mutex); | |
924 | + | |
925 | + return err; | |
926 | +} | |
927 | + | |
928 | +static int ovl_unlink(struct inode *dir, struct dentry *dentry) | |
929 | +{ | |
930 | + return ovl_do_remove(dentry, false); | |
931 | +} | |
932 | + | |
933 | + | |
934 | +static int ovl_rmdir(struct inode *dir, struct dentry *dentry) | |
935 | +{ | |
936 | + int err; | |
937 | + enum ovl_path_type type; | |
938 | + | |
939 | + type = ovl_path_type(dentry); | |
940 | + if (type != OVL_PATH_UPPER) { | |
941 | + err = ovl_check_empty_and_clear(dentry, type); | |
942 | + if (err) | |
943 | + return err; | |
944 | + } | |
945 | + | |
946 | + return ovl_do_remove(dentry, true); | |
947 | +} | |
948 | + | |
949 | +static int ovl_link(struct dentry *old, struct inode *newdir, | |
950 | + struct dentry *new) | |
951 | +{ | |
952 | + int err; | |
953 | + struct dentry *olddentry; | |
954 | + struct dentry *newdentry; | |
955 | + struct dentry *upperdir; | |
c06a8ce3 | 956 | + struct inode *newinode; |
68184a5a JR |
957 | + |
958 | + err = ovl_copy_up(old); | |
959 | + if (err) | |
960 | + goto out; | |
961 | + | |
962 | + err = ovl_copy_up(new->d_parent); | |
963 | + if (err) | |
964 | + goto out; | |
965 | + | |
966 | + upperdir = ovl_dentry_upper(new->d_parent); | |
967 | + mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); | |
968 | + newdentry = ovl_lookup_create(upperdir, new); | |
969 | + err = PTR_ERR(newdentry); | |
970 | + if (IS_ERR(newdentry)) | |
971 | + goto out_unlock; | |
972 | + | |
973 | + olddentry = ovl_dentry_upper(old); | |
a25ec4e9 | 974 | + err = vfs_link(olddentry, upperdir->d_inode, newdentry, NULL); |
68184a5a JR |
975 | + if (!err) { |
976 | + if (WARN_ON(!newdentry->d_inode)) { | |
977 | + dput(newdentry); | |
978 | + err = -ENOENT; | |
979 | + goto out_unlock; | |
980 | + } | |
c06a8ce3 AM |
981 | + newinode = ovl_new_inode(old->d_sb, newdentry->d_inode->i_mode, |
982 | + new->d_fsdata); | |
983 | + if (!newinode) { | |
984 | + err = -ENOMEM; | |
985 | + goto link_fail; | |
986 | + } | |
987 | + ovl_copyattr(upperdir->d_inode, newinode); | |
68184a5a JR |
988 | + |
989 | + ovl_dentry_version_inc(new->d_parent); | |
990 | + ovl_dentry_update(new, newdentry); | |
991 | + | |
c06a8ce3 | 992 | + d_instantiate(new, newinode); |
68184a5a | 993 | + } else { |
c06a8ce3 | 994 | +link_fail: |
68184a5a JR |
995 | + if (ovl_dentry_is_opaque(new)) |
996 | + ovl_whiteout(upperdir, new); | |
997 | + dput(newdentry); | |
998 | + } | |
999 | +out_unlock: | |
1000 | + mutex_unlock(&upperdir->d_inode->i_mutex); | |
1001 | +out: | |
1002 | + return err; | |
68184a5a JR |
1003 | +} |
1004 | + | |
1005 | +static int ovl_rename(struct inode *olddir, struct dentry *old, | |
1006 | + struct inode *newdir, struct dentry *new) | |
1007 | +{ | |
1008 | + int err; | |
1009 | + enum ovl_path_type old_type; | |
1010 | + enum ovl_path_type new_type; | |
1011 | + struct dentry *old_upperdir; | |
1012 | + struct dentry *new_upperdir; | |
1013 | + struct dentry *olddentry; | |
1014 | + struct dentry *newdentry; | |
1015 | + struct dentry *trap; | |
1016 | + bool old_opaque; | |
1017 | + bool new_opaque; | |
1018 | + bool new_create = false; | |
1019 | + bool is_dir = S_ISDIR(old->d_inode->i_mode); | |
1020 | + | |
1021 | + /* Don't copy up directory trees */ | |
1022 | + old_type = ovl_path_type(old); | |
1023 | + if (old_type != OVL_PATH_UPPER && is_dir) | |
1024 | + return -EXDEV; | |
1025 | + | |
1026 | + if (new->d_inode) { | |
1027 | + new_type = ovl_path_type(new); | |
1028 | + | |
1029 | + if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) { | |
1030 | + if (ovl_dentry_lower(old)->d_inode == | |
1031 | + ovl_dentry_lower(new)->d_inode) | |
1032 | + return 0; | |
1033 | + } | |
1034 | + if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) { | |
1035 | + if (ovl_dentry_upper(old)->d_inode == | |
1036 | + ovl_dentry_upper(new)->d_inode) | |
1037 | + return 0; | |
1038 | + } | |
1039 | + | |
1040 | + if (new_type != OVL_PATH_UPPER && | |
1041 | + S_ISDIR(new->d_inode->i_mode)) { | |
1042 | + err = ovl_check_empty_and_clear(new, new_type); | |
1043 | + if (err) | |
1044 | + return err; | |
1045 | + } | |
1046 | + } else { | |
1047 | + new_type = OVL_PATH_UPPER; | |
1048 | + } | |
1049 | + | |
1050 | + err = ovl_copy_up(old); | |
1051 | + if (err) | |
1052 | + return err; | |
1053 | + | |
1054 | + err = ovl_copy_up(new->d_parent); | |
1055 | + if (err) | |
1056 | + return err; | |
1057 | + | |
1058 | + old_upperdir = ovl_dentry_upper(old->d_parent); | |
1059 | + new_upperdir = ovl_dentry_upper(new->d_parent); | |
1060 | + | |
1061 | + trap = lock_rename(new_upperdir, old_upperdir); | |
1062 | + | |
1063 | + olddentry = ovl_dentry_upper(old); | |
1064 | + newdentry = ovl_dentry_upper(new); | |
1065 | + if (newdentry) { | |
1066 | + dget(newdentry); | |
1067 | + } else { | |
1068 | + new_create = true; | |
1069 | + newdentry = ovl_lookup_create(new_upperdir, new); | |
1070 | + err = PTR_ERR(newdentry); | |
1071 | + if (IS_ERR(newdentry)) | |
1072 | + goto out_unlock; | |
1073 | + } | |
1074 | + | |
1075 | + err = -ESTALE; | |
1076 | + if (olddentry->d_parent != old_upperdir) | |
1077 | + goto out_dput; | |
1078 | + if (newdentry->d_parent != new_upperdir) | |
1079 | + goto out_dput; | |
1080 | + if (olddentry == trap) | |
1081 | + goto out_dput; | |
1082 | + if (newdentry == trap) | |
1083 | + goto out_dput; | |
1084 | + | |
1085 | + old_opaque = ovl_dentry_is_opaque(old); | |
1086 | + new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER; | |
1087 | + | |
1088 | + if (is_dir && !old_opaque && new_opaque) { | |
1089 | + err = ovl_set_opaque(olddentry); | |
1090 | + if (err) | |
1091 | + goto out_dput; | |
1092 | + } | |
1093 | + | |
1094 | + err = vfs_rename(old_upperdir->d_inode, olddentry, | |
24aef795 | 1095 | + new_upperdir->d_inode, newdentry, NULL, 0); |
68184a5a JR |
1096 | + |
1097 | + if (err) { | |
1098 | + if (new_create && ovl_dentry_is_opaque(new)) | |
1099 | + ovl_whiteout(new_upperdir, new); | |
1100 | + if (is_dir && !old_opaque && new_opaque) | |
1101 | + ovl_remove_opaque(olddentry); | |
1102 | + goto out_dput; | |
1103 | + } | |
1104 | + | |
1105 | + if (old_type != OVL_PATH_UPPER || old_opaque) | |
1106 | + err = ovl_whiteout(old_upperdir, old); | |
1107 | + if (is_dir && old_opaque && !new_opaque) | |
1108 | + ovl_remove_opaque(olddentry); | |
1109 | + | |
1110 | + if (old_opaque != new_opaque) | |
1111 | + ovl_dentry_set_opaque(old, new_opaque); | |
1112 | + | |
1113 | + ovl_dentry_version_inc(old->d_parent); | |
1114 | + ovl_dentry_version_inc(new->d_parent); | |
1115 | + | |
1116 | +out_dput: | |
1117 | + dput(newdentry); | |
1118 | +out_unlock: | |
1119 | + unlock_rename(new_upperdir, old_upperdir); | |
1120 | + return err; | |
1121 | +} | |
1122 | + | |
1123 | +const struct inode_operations ovl_dir_inode_operations = { | |
1124 | + .lookup = ovl_lookup, | |
1125 | + .mkdir = ovl_mkdir, | |
1126 | + .symlink = ovl_symlink, | |
1127 | + .unlink = ovl_unlink, | |
1128 | + .rmdir = ovl_rmdir, | |
1129 | + .rename = ovl_rename, | |
1130 | + .link = ovl_link, | |
1131 | + .setattr = ovl_setattr, | |
1132 | + .create = ovl_create, | |
1133 | + .mknod = ovl_mknod, | |
1134 | + .permission = ovl_permission, | |
1135 | + .getattr = ovl_dir_getattr, | |
1136 | + .setxattr = ovl_setxattr, | |
1137 | + .getxattr = ovl_getxattr, | |
1138 | + .listxattr = ovl_listxattr, | |
1139 | + .removexattr = ovl_removexattr, | |
1140 | +}; | |
514e5dae AM |
1141 | --- /dev/null |
1142 | +++ b/fs/overlayfs/inode.c | |
c06a8ce3 | 1143 | @@ -0,0 +1,372 @@ |
68184a5a JR |
1144 | +/* |
1145 | + * | |
1146 | + * Copyright (C) 2011 Novell Inc. | |
1147 | + * | |
1148 | + * This program is free software; you can redistribute it and/or modify it | |
1149 | + * under the terms of the GNU General Public License version 2 as published by | |
1150 | + * the Free Software Foundation. | |
1151 | + */ | |
1152 | + | |
1153 | +#include <linux/fs.h> | |
1154 | +#include <linux/slab.h> | |
1155 | +#include <linux/xattr.h> | |
1156 | +#include "overlayfs.h" | |
1157 | + | |
1158 | +int ovl_setattr(struct dentry *dentry, struct iattr *attr) | |
1159 | +{ | |
1160 | + struct dentry *upperdentry; | |
1161 | + int err; | |
1162 | + | |
1163 | + if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry)) | |
1164 | + err = ovl_copy_up_truncate(dentry, attr->ia_size); | |
1165 | + else | |
1166 | + err = ovl_copy_up(dentry); | |
1167 | + if (err) | |
1168 | + return err; | |
1169 | + | |
1170 | + upperdentry = ovl_dentry_upper(dentry); | |
1171 | + | |
1172 | + if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) | |
1173 | + attr->ia_valid &= ~ATTR_MODE; | |
1174 | + | |
1175 | + mutex_lock(&upperdentry->d_inode->i_mutex); | |
a25ec4e9 | 1176 | + err = notify_change(upperdentry, attr, NULL); |
c06a8ce3 AM |
1177 | + if (!err) |
1178 | + ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
68184a5a JR |
1179 | + mutex_unlock(&upperdentry->d_inode->i_mutex); |
1180 | + | |
1181 | + return err; | |
1182 | +} | |
1183 | + | |
1184 | +static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
1185 | + struct kstat *stat) | |
1186 | +{ | |
1187 | + struct path realpath; | |
1188 | + | |
1189 | + ovl_path_real(dentry, &realpath); | |
514e5dae | 1190 | + return vfs_getattr(&realpath, stat); |
68184a5a JR |
1191 | +} |
1192 | + | |
1193 | +int ovl_permission(struct inode *inode, int mask) | |
1194 | +{ | |
1195 | + struct ovl_entry *oe; | |
1196 | + struct dentry *alias = NULL; | |
1197 | + struct inode *realinode; | |
1198 | + struct dentry *realdentry; | |
1199 | + bool is_upper; | |
1200 | + int err; | |
1201 | + | |
1202 | + if (S_ISDIR(inode->i_mode)) { | |
1203 | + oe = inode->i_private; | |
1204 | + } else if (mask & MAY_NOT_BLOCK) { | |
1205 | + return -ECHILD; | |
1206 | + } else { | |
1207 | + /* | |
1208 | + * For non-directories find an alias and get the info | |
1209 | + * from there. | |
1210 | + */ | |
1211 | + alias = d_find_any_alias(inode); | |
1212 | + if (WARN_ON(!alias)) | |
1213 | + return -ENOENT; | |
1214 | + | |
1215 | + oe = alias->d_fsdata; | |
1216 | + } | |
1217 | + | |
1218 | + realdentry = ovl_entry_real(oe, &is_upper); | |
1219 | + | |
1220 | + /* Careful in RCU walk mode */ | |
1221 | + realinode = ACCESS_ONCE(realdentry->d_inode); | |
1222 | + if (!realinode) { | |
1223 | + WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
1224 | + err = -ENOENT; | |
1225 | + goto out_dput; | |
1226 | + } | |
1227 | + | |
1228 | + if (mask & MAY_WRITE) { | |
1229 | + umode_t mode = realinode->i_mode; | |
1230 | + | |
1231 | + /* | |
1232 | + * Writes will always be redirected to upper layer, so | |
1233 | + * ignore lower layer being read-only. | |
1234 | + * | |
1235 | + * If the overlay itself is read-only then proceed | |
1236 | + * with the permission check, don't return EROFS. | |
1237 | + * This will only happen if this is the lower layer of | |
1238 | + * another overlayfs. | |
1239 | + * | |
1240 | + * If upper fs becomes read-only after the overlay was | |
1241 | + * constructed return EROFS to prevent modification of | |
1242 | + * upper layer. | |
1243 | + */ | |
1244 | + err = -EROFS; | |
1245 | + if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) && | |
1246 | + (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
1247 | + goto out_dput; | |
68184a5a JR |
1248 | + } |
1249 | + | |
c06a8ce3 | 1250 | + err = __inode_permission(realinode, mask); |
68184a5a JR |
1251 | +out_dput: |
1252 | + dput(alias); | |
1253 | + return err; | |
1254 | +} | |
1255 | + | |
1256 | + | |
1257 | +struct ovl_link_data { | |
1258 | + struct dentry *realdentry; | |
1259 | + void *cookie; | |
1260 | +}; | |
1261 | + | |
1262 | +static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd) | |
1263 | +{ | |
1264 | + void *ret; | |
1265 | + struct dentry *realdentry; | |
1266 | + struct inode *realinode; | |
1267 | + | |
1268 | + realdentry = ovl_dentry_real(dentry); | |
1269 | + realinode = realdentry->d_inode; | |
1270 | + | |
1271 | + if (WARN_ON(!realinode->i_op->follow_link)) | |
1272 | + return ERR_PTR(-EPERM); | |
1273 | + | |
1274 | + ret = realinode->i_op->follow_link(realdentry, nd); | |
1275 | + if (IS_ERR(ret)) | |
1276 | + return ret; | |
1277 | + | |
1278 | + if (realinode->i_op->put_link) { | |
1279 | + struct ovl_link_data *data; | |
1280 | + | |
1281 | + data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL); | |
1282 | + if (!data) { | |
1283 | + realinode->i_op->put_link(realdentry, nd, ret); | |
1284 | + return ERR_PTR(-ENOMEM); | |
1285 | + } | |
1286 | + data->realdentry = realdentry; | |
1287 | + data->cookie = ret; | |
1288 | + | |
1289 | + return data; | |
1290 | + } else { | |
1291 | + return NULL; | |
1292 | + } | |
1293 | +} | |
1294 | + | |
1295 | +static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c) | |
1296 | +{ | |
1297 | + struct inode *realinode; | |
1298 | + struct ovl_link_data *data = c; | |
1299 | + | |
1300 | + if (!data) | |
1301 | + return; | |
1302 | + | |
1303 | + realinode = data->realdentry->d_inode; | |
1304 | + realinode->i_op->put_link(data->realdentry, nd, data->cookie); | |
1305 | + kfree(data); | |
1306 | +} | |
1307 | + | |
1308 | +static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) | |
1309 | +{ | |
1310 | + struct path realpath; | |
1311 | + struct inode *realinode; | |
1312 | + | |
1313 | + ovl_path_real(dentry, &realpath); | |
1314 | + realinode = realpath.dentry->d_inode; | |
1315 | + | |
1316 | + if (!realinode->i_op->readlink) | |
1317 | + return -EINVAL; | |
1318 | + | |
1319 | + touch_atime(&realpath); | |
1320 | + | |
1321 | + return realinode->i_op->readlink(realpath.dentry, buf, bufsiz); | |
1322 | +} | |
1323 | + | |
1324 | + | |
1325 | +static bool ovl_is_private_xattr(const char *name) | |
1326 | +{ | |
1327 | + return strncmp(name, "trusted.overlay.", 14) == 0; | |
1328 | +} | |
1329 | + | |
1330 | +int ovl_setxattr(struct dentry *dentry, const char *name, | |
1331 | + const void *value, size_t size, int flags) | |
1332 | +{ | |
1333 | + int err; | |
1334 | + struct dentry *upperdentry; | |
1335 | + | |
1336 | + if (ovl_is_private_xattr(name)) | |
1337 | + return -EPERM; | |
1338 | + | |
1339 | + err = ovl_copy_up(dentry); | |
1340 | + if (err) | |
1341 | + return err; | |
1342 | + | |
1343 | + upperdentry = ovl_dentry_upper(dentry); | |
1344 | + return vfs_setxattr(upperdentry, name, value, size, flags); | |
1345 | +} | |
1346 | + | |
1347 | +ssize_t ovl_getxattr(struct dentry *dentry, const char *name, | |
1348 | + void *value, size_t size) | |
1349 | +{ | |
1350 | + if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE && | |
1351 | + ovl_is_private_xattr(name)) | |
1352 | + return -ENODATA; | |
1353 | + | |
1354 | + return vfs_getxattr(ovl_dentry_real(dentry), name, value, size); | |
1355 | +} | |
1356 | + | |
1357 | +ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
1358 | +{ | |
1359 | + ssize_t res; | |
1360 | + int off; | |
1361 | + | |
1362 | + res = vfs_listxattr(ovl_dentry_real(dentry), list, size); | |
1363 | + if (res <= 0 || size == 0) | |
1364 | + return res; | |
1365 | + | |
1366 | + if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE) | |
1367 | + return res; | |
1368 | + | |
1369 | + /* filter out private xattrs */ | |
1370 | + for (off = 0; off < res;) { | |
1371 | + char *s = list + off; | |
1372 | + size_t slen = strlen(s) + 1; | |
1373 | + | |
1374 | + BUG_ON(off + slen > res); | |
1375 | + | |
1376 | + if (ovl_is_private_xattr(s)) { | |
1377 | + res -= slen; | |
1378 | + memmove(s, s + slen, res - off); | |
1379 | + } else { | |
1380 | + off += slen; | |
1381 | + } | |
1382 | + } | |
1383 | + | |
1384 | + return res; | |
1385 | +} | |
1386 | + | |
1387 | +int ovl_removexattr(struct dentry *dentry, const char *name) | |
1388 | +{ | |
1389 | + int err; | |
1390 | + struct path realpath; | |
1391 | + enum ovl_path_type type; | |
1392 | + | |
1393 | + if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE && | |
1394 | + ovl_is_private_xattr(name)) | |
1395 | + return -ENODATA; | |
1396 | + | |
1397 | + type = ovl_path_real(dentry, &realpath); | |
1398 | + if (type == OVL_PATH_LOWER) { | |
1399 | + err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
1400 | + if (err < 0) | |
1401 | + return err; | |
1402 | + | |
1403 | + err = ovl_copy_up(dentry); | |
1404 | + if (err) | |
1405 | + return err; | |
1406 | + | |
1407 | + ovl_path_upper(dentry, &realpath); | |
1408 | + } | |
1409 | + | |
1410 | + return vfs_removexattr(realpath.dentry, name); | |
1411 | +} | |
1412 | + | |
1413 | +static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, | |
1414 | + struct dentry *realdentry) | |
1415 | +{ | |
1416 | + if (type != OVL_PATH_LOWER) | |
1417 | + return false; | |
1418 | + | |
1419 | + if (special_file(realdentry->d_inode->i_mode)) | |
1420 | + return false; | |
1421 | + | |
1422 | + if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
1423 | + return false; | |
1424 | + | |
1425 | + return true; | |
1426 | +} | |
1427 | + | |
1428 | +static int ovl_dentry_open(struct dentry *dentry, struct file *file, | |
1429 | + const struct cred *cred) | |
1430 | +{ | |
1431 | + int err; | |
1432 | + struct path realpath; | |
1433 | + enum ovl_path_type type; | |
1434 | + | |
1435 | + type = ovl_path_real(dentry, &realpath); | |
1436 | + if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) { | |
1437 | + if (file->f_flags & O_TRUNC) | |
1438 | + err = ovl_copy_up_truncate(dentry, 0); | |
1439 | + else | |
1440 | + err = ovl_copy_up(dentry); | |
1441 | + if (err) | |
1442 | + return err; | |
1443 | + | |
1444 | + ovl_path_upper(dentry, &realpath); | |
1445 | + } | |
1446 | + | |
1447 | + return vfs_open(&realpath, file, cred); | |
1448 | +} | |
1449 | + | |
1450 | +static const struct inode_operations ovl_file_inode_operations = { | |
1451 | + .setattr = ovl_setattr, | |
1452 | + .permission = ovl_permission, | |
1453 | + .getattr = ovl_getattr, | |
1454 | + .setxattr = ovl_setxattr, | |
1455 | + .getxattr = ovl_getxattr, | |
1456 | + .listxattr = ovl_listxattr, | |
1457 | + .removexattr = ovl_removexattr, | |
1458 | + .dentry_open = ovl_dentry_open, | |
1459 | +}; | |
1460 | + | |
1461 | +static const struct inode_operations ovl_symlink_inode_operations = { | |
1462 | + .setattr = ovl_setattr, | |
1463 | + .follow_link = ovl_follow_link, | |
1464 | + .put_link = ovl_put_link, | |
1465 | + .readlink = ovl_readlink, | |
1466 | + .getattr = ovl_getattr, | |
1467 | + .setxattr = ovl_setxattr, | |
1468 | + .getxattr = ovl_getxattr, | |
1469 | + .listxattr = ovl_listxattr, | |
1470 | + .removexattr = ovl_removexattr, | |
1471 | +}; | |
1472 | + | |
1473 | +struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, | |
1474 | + struct ovl_entry *oe) | |
1475 | +{ | |
1476 | + struct inode *inode; | |
1477 | + | |
1478 | + inode = new_inode(sb); | |
1479 | + if (!inode) | |
1480 | + return NULL; | |
1481 | + | |
1482 | + mode &= S_IFMT; | |
1483 | + | |
1484 | + inode->i_ino = get_next_ino(); | |
1485 | + inode->i_mode = mode; | |
1486 | + inode->i_flags |= S_NOATIME | S_NOCMTIME; | |
1487 | + | |
1488 | + switch (mode) { | |
1489 | + case S_IFDIR: | |
1490 | + inode->i_private = oe; | |
1491 | + inode->i_op = &ovl_dir_inode_operations; | |
1492 | + inode->i_fop = &ovl_dir_operations; | |
1493 | + break; | |
1494 | + | |
1495 | + case S_IFLNK: | |
1496 | + inode->i_op = &ovl_symlink_inode_operations; | |
1497 | + break; | |
1498 | + | |
1499 | + case S_IFREG: | |
1500 | + case S_IFSOCK: | |
1501 | + case S_IFBLK: | |
1502 | + case S_IFCHR: | |
1503 | + case S_IFIFO: | |
1504 | + inode->i_op = &ovl_file_inode_operations; | |
1505 | + break; | |
1506 | + | |
1507 | + default: | |
1508 | + WARN(1, "illegal file type: %i\n", mode); | |
c06a8ce3 | 1509 | + iput(inode); |
68184a5a JR |
1510 | + inode = NULL; |
1511 | + } | |
1512 | + | |
1513 | + return inode; | |
1514 | + | |
1515 | +} | |
514e5dae AM |
1516 | --- /dev/null |
1517 | +++ b/fs/overlayfs/overlayfs.h | |
c06a8ce3 | 1518 | @@ -0,0 +1,70 @@ |
68184a5a JR |
1519 | +/* |
1520 | + * | |
1521 | + * Copyright (C) 2011 Novell Inc. | |
1522 | + * | |
1523 | + * This program is free software; you can redistribute it and/or modify it | |
1524 | + * under the terms of the GNU General Public License version 2 as published by | |
1525 | + * the Free Software Foundation. | |
1526 | + */ | |
1527 | + | |
1528 | +struct ovl_entry; | |
1529 | + | |
1530 | +enum ovl_path_type { | |
1531 | + OVL_PATH_UPPER, | |
1532 | + OVL_PATH_MERGE, | |
1533 | + OVL_PATH_LOWER, | |
1534 | +}; | |
1535 | + | |
1536 | +extern const char *ovl_opaque_xattr; | |
1537 | +extern const char *ovl_whiteout_xattr; | |
1538 | +extern const struct dentry_operations ovl_dentry_operations; | |
1539 | + | |
1540 | +enum ovl_path_type ovl_path_type(struct dentry *dentry); | |
1541 | +u64 ovl_dentry_version_get(struct dentry *dentry); | |
1542 | +void ovl_dentry_version_inc(struct dentry *dentry); | |
1543 | +void ovl_path_upper(struct dentry *dentry, struct path *path); | |
1544 | +void ovl_path_lower(struct dentry *dentry, struct path *path); | |
1545 | +enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); | |
1546 | +struct dentry *ovl_dentry_upper(struct dentry *dentry); | |
1547 | +struct dentry *ovl_dentry_lower(struct dentry *dentry); | |
1548 | +struct dentry *ovl_dentry_real(struct dentry *dentry); | |
1549 | +struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper); | |
1550 | +bool ovl_dentry_is_opaque(struct dentry *dentry); | |
1551 | +void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque); | |
1552 | +bool ovl_is_whiteout(struct dentry *dentry); | |
1553 | +void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry); | |
1554 | +struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, | |
1555 | + unsigned int flags); | |
1556 | +struct file *ovl_path_open(struct path *path, int flags); | |
1557 | + | |
1558 | +struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, | |
1559 | + struct kstat *stat, const char *link); | |
1560 | + | |
1561 | +/* readdir.c */ | |
1562 | +extern const struct file_operations ovl_dir_operations; | |
1563 | +int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type); | |
1564 | + | |
1565 | +/* inode.c */ | |
1566 | +int ovl_setattr(struct dentry *dentry, struct iattr *attr); | |
1567 | +int ovl_permission(struct inode *inode, int mask); | |
1568 | +int ovl_setxattr(struct dentry *dentry, const char *name, | |
1569 | + const void *value, size_t size, int flags); | |
1570 | +ssize_t ovl_getxattr(struct dentry *dentry, const char *name, | |
1571 | + void *value, size_t size); | |
1572 | +ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); | |
1573 | +int ovl_removexattr(struct dentry *dentry, const char *name); | |
1574 | + | |
1575 | +struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, | |
1576 | + struct ovl_entry *oe); | |
c06a8ce3 AM |
1577 | +static inline void ovl_copyattr(struct inode *from, struct inode *to) |
1578 | +{ | |
1579 | + to->i_uid = from->i_uid; | |
1580 | + to->i_gid = from->i_gid; | |
1581 | +} | |
1582 | + | |
68184a5a JR |
1583 | +/* dir.c */ |
1584 | +extern const struct inode_operations ovl_dir_inode_operations; | |
1585 | + | |
1586 | +/* copy_up.c */ | |
1587 | +int ovl_copy_up(struct dentry *dentry); | |
1588 | +int ovl_copy_up_truncate(struct dentry *dentry, loff_t size); | |
514e5dae AM |
1589 | --- /dev/null |
1590 | +++ b/fs/overlayfs/readdir.c | |
392086de | 1591 | @@ -0,0 +1,567 @@ |
68184a5a JR |
1592 | +/* |
1593 | + * | |
1594 | + * Copyright (C) 2011 Novell Inc. | |
1595 | + * | |
1596 | + * This program is free software; you can redistribute it and/or modify it | |
1597 | + * under the terms of the GNU General Public License version 2 as published by | |
1598 | + * the Free Software Foundation. | |
1599 | + */ | |
1600 | + | |
1601 | +#include <linux/fs.h> | |
1602 | +#include <linux/slab.h> | |
1603 | +#include <linux/namei.h> | |
1604 | +#include <linux/file.h> | |
1605 | +#include <linux/xattr.h> | |
1606 | +#include <linux/rbtree.h> | |
1607 | +#include <linux/security.h> | |
1608 | +#include <linux/cred.h> | |
1609 | +#include "overlayfs.h" | |
1610 | + | |
1611 | +struct ovl_cache_entry { | |
1612 | + const char *name; | |
1613 | + unsigned int len; | |
1614 | + unsigned int type; | |
1615 | + u64 ino; | |
1616 | + bool is_whiteout; | |
1617 | + struct list_head l_node; | |
1618 | + struct rb_node node; | |
1619 | +}; | |
1620 | + | |
1621 | +struct ovl_readdir_data { | |
392086de AM |
1622 | + struct dir_context ctx; |
1623 | + bool is_merge; | |
68184a5a JR |
1624 | + struct rb_root *root; |
1625 | + struct list_head *list; | |
1626 | + struct list_head *middle; | |
1627 | + struct dentry *dir; | |
1628 | + int count; | |
1629 | + int err; | |
1630 | +}; | |
1631 | + | |
1632 | +struct ovl_dir_file { | |
1633 | + bool is_real; | |
1634 | + bool is_cached; | |
1635 | + struct list_head cursor; | |
1636 | + u64 cache_version; | |
1637 | + struct list_head cache; | |
1638 | + struct file *realfile; | |
1639 | +}; | |
1640 | + | |
1641 | +static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) | |
1642 | +{ | |
1643 | + return container_of(n, struct ovl_cache_entry, node); | |
1644 | +} | |
1645 | + | |
1646 | +static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, | |
1647 | + const char *name, int len) | |
1648 | +{ | |
1649 | + struct rb_node *node = root->rb_node; | |
1650 | + int cmp; | |
1651 | + | |
1652 | + while (node) { | |
1653 | + struct ovl_cache_entry *p = ovl_cache_entry_from_node(node); | |
1654 | + | |
1655 | + cmp = strncmp(name, p->name, len); | |
1656 | + if (cmp > 0) | |
1657 | + node = p->node.rb_right; | |
1658 | + else if (cmp < 0 || len < p->len) | |
1659 | + node = p->node.rb_left; | |
1660 | + else | |
1661 | + return p; | |
1662 | + } | |
1663 | + | |
1664 | + return NULL; | |
1665 | +} | |
1666 | + | |
1667 | +static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len, | |
1668 | + u64 ino, unsigned int d_type) | |
1669 | +{ | |
1670 | + struct ovl_cache_entry *p; | |
1671 | + | |
1672 | + p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL); | |
1673 | + if (p) { | |
1674 | + char *name_copy = (char *) (p + 1); | |
1675 | + memcpy(name_copy, name, len); | |
1676 | + name_copy[len] = '\0'; | |
1677 | + p->name = name_copy; | |
1678 | + p->len = len; | |
1679 | + p->type = d_type; | |
1680 | + p->ino = ino; | |
1681 | + p->is_whiteout = false; | |
1682 | + } | |
1683 | + | |
1684 | + return p; | |
1685 | +} | |
1686 | + | |
1687 | +static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, | |
1688 | + const char *name, int len, u64 ino, | |
1689 | + unsigned int d_type) | |
1690 | +{ | |
1691 | + struct rb_node **newp = &rdd->root->rb_node; | |
1692 | + struct rb_node *parent = NULL; | |
1693 | + struct ovl_cache_entry *p; | |
1694 | + | |
1695 | + while (*newp) { | |
1696 | + int cmp; | |
1697 | + struct ovl_cache_entry *tmp; | |
1698 | + | |
1699 | + parent = *newp; | |
1700 | + tmp = ovl_cache_entry_from_node(*newp); | |
1701 | + cmp = strncmp(name, tmp->name, len); | |
1702 | + if (cmp > 0) | |
1703 | + newp = &tmp->node.rb_right; | |
1704 | + else if (cmp < 0 || len < tmp->len) | |
1705 | + newp = &tmp->node.rb_left; | |
1706 | + else | |
1707 | + return 0; | |
1708 | + } | |
1709 | + | |
1710 | + p = ovl_cache_entry_new(name, len, ino, d_type); | |
1711 | + if (p == NULL) | |
1712 | + return -ENOMEM; | |
1713 | + | |
1714 | + list_add_tail(&p->l_node, rdd->list); | |
1715 | + rb_link_node(&p->node, parent, newp); | |
1716 | + rb_insert_color(&p->node, rdd->root); | |
1717 | + | |
1718 | + return 0; | |
1719 | +} | |
1720 | + | |
392086de AM |
1721 | +static int ovl_fill_lower(struct ovl_readdir_data *rdd, |
1722 | + const char *name, int namelen, | |
1723 | + loff_t offset, u64 ino, unsigned int d_type) | |
68184a5a | 1724 | +{ |
68184a5a JR |
1725 | + struct ovl_cache_entry *p; |
1726 | + | |
68184a5a JR |
1727 | + p = ovl_cache_entry_find(rdd->root, name, namelen); |
1728 | + if (p) { | |
1729 | + list_move_tail(&p->l_node, rdd->middle); | |
1730 | + } else { | |
1731 | + p = ovl_cache_entry_new(name, namelen, ino, d_type); | |
1732 | + if (p == NULL) | |
1733 | + rdd->err = -ENOMEM; | |
1734 | + else | |
1735 | + list_add_tail(&p->l_node, rdd->middle); | |
1736 | + } | |
1737 | + | |
1738 | + return rdd->err; | |
1739 | +} | |
1740 | + | |
1741 | +static void ovl_cache_free(struct list_head *list) | |
1742 | +{ | |
1743 | + struct ovl_cache_entry *p; | |
1744 | + struct ovl_cache_entry *n; | |
1745 | + | |
1746 | + list_for_each_entry_safe(p, n, list, l_node) | |
1747 | + kfree(p); | |
1748 | + | |
1749 | + INIT_LIST_HEAD(list); | |
1750 | +} | |
1751 | + | |
392086de | 1752 | +static int ovl_fill_merge(void *buf, const char *name, int namelen, |
68184a5a JR |
1753 | + loff_t offset, u64 ino, unsigned int d_type) |
1754 | +{ | |
1755 | + struct ovl_readdir_data *rdd = buf; | |
1756 | + | |
1757 | + rdd->count++; | |
392086de AM |
1758 | + if (!rdd->is_merge) |
1759 | + return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); | |
1760 | + else | |
1761 | + return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type); | |
68184a5a JR |
1762 | +} |
1763 | + | |
1764 | +static inline int ovl_dir_read(struct path *realpath, | |
392086de | 1765 | + struct ovl_readdir_data *rdd) |
68184a5a JR |
1766 | +{ |
1767 | + struct file *realfile; | |
1768 | + int err; | |
1769 | + | |
1770 | + realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY); | |
1771 | + if (IS_ERR(realfile)) | |
1772 | + return PTR_ERR(realfile); | |
1773 | + | |
392086de | 1774 | + rdd->ctx.pos = 0; |
68184a5a JR |
1775 | + do { |
1776 | + rdd->count = 0; | |
1777 | + rdd->err = 0; | |
392086de | 1778 | + err = iterate_dir(realfile, &rdd->ctx); |
68184a5a JR |
1779 | + if (err >= 0) |
1780 | + err = rdd->err; | |
1781 | + } while (!err && rdd->count); | |
1782 | + fput(realfile); | |
1783 | + | |
1784 | + return 0; | |
1785 | +} | |
1786 | + | |
1787 | +static void ovl_dir_reset(struct file *file) | |
1788 | +{ | |
1789 | + struct ovl_dir_file *od = file->private_data; | |
1790 | + enum ovl_path_type type = ovl_path_type(file->f_path.dentry); | |
1791 | + | |
1792 | + if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) { | |
1793 | + list_del_init(&od->cursor); | |
1794 | + ovl_cache_free(&od->cache); | |
1795 | + od->is_cached = false; | |
1796 | + } | |
1797 | + WARN_ON(!od->is_real && type != OVL_PATH_MERGE); | |
1798 | + if (od->is_real && type == OVL_PATH_MERGE) { | |
1799 | + fput(od->realfile); | |
1800 | + od->realfile = NULL; | |
1801 | + od->is_real = false; | |
1802 | + } | |
1803 | +} | |
1804 | + | |
1805 | +static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd) | |
1806 | +{ | |
1807 | + struct ovl_cache_entry *p; | |
1808 | + struct dentry *dentry; | |
1809 | + const struct cred *old_cred; | |
1810 | + struct cred *override_cred; | |
1811 | + | |
1812 | + override_cred = prepare_creds(); | |
1813 | + if (!override_cred) { | |
1814 | + ovl_cache_free(rdd->list); | |
1815 | + return -ENOMEM; | |
1816 | + } | |
1817 | + | |
1818 | + /* | |
1819 | + * CAP_SYS_ADMIN for getxattr | |
1820 | + * CAP_DAC_OVERRIDE for lookup | |
1821 | + */ | |
1822 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
1823 | + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
1824 | + old_cred = override_creds(override_cred); | |
1825 | + | |
1826 | + mutex_lock(&rdd->dir->d_inode->i_mutex); | |
1827 | + list_for_each_entry(p, rdd->list, l_node) { | |
1828 | + if (p->type != DT_LNK) | |
1829 | + continue; | |
1830 | + | |
1831 | + dentry = lookup_one_len(p->name, rdd->dir, p->len); | |
1832 | + if (IS_ERR(dentry)) | |
1833 | + continue; | |
1834 | + | |
1835 | + p->is_whiteout = ovl_is_whiteout(dentry); | |
1836 | + dput(dentry); | |
1837 | + } | |
1838 | + mutex_unlock(&rdd->dir->d_inode->i_mutex); | |
1839 | + | |
1840 | + revert_creds(old_cred); | |
1841 | + put_cred(override_cred); | |
1842 | + | |
1843 | + return 0; | |
1844 | +} | |
1845 | + | |
1846 | +static inline int ovl_dir_read_merged(struct path *upperpath, | |
1847 | + struct path *lowerpath, | |
392086de | 1848 | + struct list_head *list) |
68184a5a JR |
1849 | +{ |
1850 | + int err; | |
1851 | + struct rb_root root = RB_ROOT; | |
1852 | + struct list_head middle; | |
392086de AM |
1853 | + struct ovl_readdir_data rdd = { |
1854 | + .ctx.actor = ovl_fill_merge, | |
1855 | + .list = list, | |
1856 | + .root = &root, | |
1857 | + .is_merge = false, | |
1858 | + }; | |
68184a5a | 1859 | + |
68184a5a | 1860 | + if (upperpath->dentry) { |
392086de AM |
1861 | + rdd.dir = upperpath->dentry; |
1862 | + err = ovl_dir_read(upperpath, &rdd); | |
68184a5a JR |
1863 | + if (err) |
1864 | + goto out; | |
1865 | + | |
392086de | 1866 | + err = ovl_dir_mark_whiteouts(&rdd); |
68184a5a JR |
1867 | + if (err) |
1868 | + goto out; | |
1869 | + } | |
1870 | + /* | |
1871 | + * Insert lowerpath entries before upperpath ones, this allows | |
1872 | + * offsets to be reasonably constant | |
1873 | + */ | |
392086de AM |
1874 | + list_add(&middle, rdd.list); |
1875 | + rdd.middle = &middle; | |
1876 | + rdd.is_merge = true; | |
1877 | + err = ovl_dir_read(lowerpath, &rdd); | |
68184a5a JR |
1878 | + list_del(&middle); |
1879 | +out: | |
68184a5a JR |
1880 | + return err; |
1881 | +} | |
1882 | + | |
1883 | +static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) | |
1884 | +{ | |
1885 | + struct list_head *l; | |
1886 | + loff_t off; | |
1887 | + | |
1888 | + l = od->cache.next; | |
1889 | + for (off = 0; off < pos; off++) { | |
1890 | + if (l == &od->cache) | |
1891 | + break; | |
1892 | + l = l->next; | |
1893 | + } | |
1894 | + list_move_tail(&od->cursor, l); | |
1895 | +} | |
1896 | + | |
392086de | 1897 | +static int ovl_iterate(struct file *file, struct dir_context *ctx) |
68184a5a JR |
1898 | +{ |
1899 | + struct ovl_dir_file *od = file->private_data; | |
1900 | + int res; | |
1901 | + | |
392086de | 1902 | + if (!ctx->pos) |
68184a5a JR |
1903 | + ovl_dir_reset(file); |
1904 | + | |
1905 | + if (od->is_real) { | |
392086de | 1906 | + res = iterate_dir(od->realfile, ctx); |
68184a5a JR |
1907 | + |
1908 | + return res; | |
1909 | + } | |
1910 | + | |
1911 | + if (!od->is_cached) { | |
1912 | + struct path lowerpath; | |
1913 | + struct path upperpath; | |
68184a5a JR |
1914 | + |
1915 | + ovl_path_lower(file->f_path.dentry, &lowerpath); | |
1916 | + ovl_path_upper(file->f_path.dentry, &upperpath); | |
1917 | + | |
392086de | 1918 | + res = ovl_dir_read_merged(&upperpath, &lowerpath, &od->cache); |
68184a5a | 1919 | + if (res) { |
392086de | 1920 | + ovl_cache_free(&od->cache); |
68184a5a JR |
1921 | + return res; |
1922 | + } | |
1923 | + | |
1924 | + od->cache_version = ovl_dentry_version_get(file->f_path.dentry); | |
1925 | + od->is_cached = true; | |
1926 | + | |
392086de | 1927 | + ovl_seek_cursor(od, ctx->pos); |
68184a5a JR |
1928 | + } |
1929 | + | |
1930 | + while (od->cursor.next != &od->cache) { | |
68184a5a JR |
1931 | + struct ovl_cache_entry *p; |
1932 | + | |
1933 | + p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node); | |
68184a5a | 1934 | + if (!p->is_whiteout) { |
392086de | 1935 | + if (!dir_emit(ctx, p->name, p->len, p->ino, p->type)) |
68184a5a JR |
1936 | + break; |
1937 | + } | |
392086de | 1938 | + ctx->pos++; |
68184a5a JR |
1939 | + list_move(&od->cursor, &p->l_node); |
1940 | + } | |
1941 | + | |
1942 | + return 0; | |
1943 | +} | |
1944 | + | |
1945 | +static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) | |
1946 | +{ | |
1947 | + loff_t res; | |
1948 | + struct ovl_dir_file *od = file->private_data; | |
1949 | + | |
c06a8ce3 | 1950 | + mutex_lock(&file_inode(file)->i_mutex); |
68184a5a JR |
1951 | + if (!file->f_pos) |
1952 | + ovl_dir_reset(file); | |
1953 | + | |
1954 | + if (od->is_real) { | |
1955 | + res = vfs_llseek(od->realfile, offset, origin); | |
1956 | + file->f_pos = od->realfile->f_pos; | |
1957 | + } else { | |
1958 | + res = -EINVAL; | |
1959 | + | |
1960 | + switch (origin) { | |
1961 | + case SEEK_CUR: | |
1962 | + offset += file->f_pos; | |
1963 | + break; | |
1964 | + case SEEK_SET: | |
1965 | + break; | |
1966 | + default: | |
1967 | + goto out_unlock; | |
1968 | + } | |
1969 | + if (offset < 0) | |
1970 | + goto out_unlock; | |
1971 | + | |
1972 | + if (offset != file->f_pos) { | |
1973 | + file->f_pos = offset; | |
1974 | + if (od->is_cached) | |
1975 | + ovl_seek_cursor(od, offset); | |
1976 | + } | |
1977 | + res = offset; | |
1978 | + } | |
1979 | +out_unlock: | |
c06a8ce3 | 1980 | + mutex_unlock(&file_inode(file)->i_mutex); |
68184a5a JR |
1981 | + |
1982 | + return res; | |
1983 | +} | |
1984 | + | |
1985 | +static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, | |
1986 | + int datasync) | |
1987 | +{ | |
1988 | + struct ovl_dir_file *od = file->private_data; | |
1989 | + | |
1990 | + /* May need to reopen directory if it got copied up */ | |
1991 | + if (!od->realfile) { | |
1992 | + struct path upperpath; | |
1993 | + | |
1994 | + ovl_path_upper(file->f_path.dentry, &upperpath); | |
1995 | + od->realfile = ovl_path_open(&upperpath, O_RDONLY); | |
1996 | + if (IS_ERR(od->realfile)) | |
1997 | + return PTR_ERR(od->realfile); | |
1998 | + } | |
1999 | + | |
2000 | + return vfs_fsync_range(od->realfile, start, end, datasync); | |
2001 | +} | |
2002 | + | |
2003 | +static int ovl_dir_release(struct inode *inode, struct file *file) | |
2004 | +{ | |
2005 | + struct ovl_dir_file *od = file->private_data; | |
2006 | + | |
2007 | + list_del(&od->cursor); | |
2008 | + ovl_cache_free(&od->cache); | |
2009 | + if (od->realfile) | |
2010 | + fput(od->realfile); | |
2011 | + kfree(od); | |
2012 | + | |
2013 | + return 0; | |
2014 | +} | |
2015 | + | |
2016 | +static int ovl_dir_open(struct inode *inode, struct file *file) | |
2017 | +{ | |
2018 | + struct path realpath; | |
2019 | + struct file *realfile; | |
2020 | + struct ovl_dir_file *od; | |
2021 | + enum ovl_path_type type; | |
2022 | + | |
2023 | + od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); | |
2024 | + if (!od) | |
2025 | + return -ENOMEM; | |
2026 | + | |
2027 | + type = ovl_path_real(file->f_path.dentry, &realpath); | |
2028 | + realfile = ovl_path_open(&realpath, file->f_flags); | |
2029 | + if (IS_ERR(realfile)) { | |
2030 | + kfree(od); | |
2031 | + return PTR_ERR(realfile); | |
2032 | + } | |
2033 | + INIT_LIST_HEAD(&od->cache); | |
2034 | + INIT_LIST_HEAD(&od->cursor); | |
2035 | + od->is_cached = false; | |
2036 | + od->realfile = realfile; | |
2037 | + od->is_real = (type != OVL_PATH_MERGE); | |
2038 | + file->private_data = od; | |
2039 | + | |
2040 | + return 0; | |
2041 | +} | |
2042 | + | |
2043 | +const struct file_operations ovl_dir_operations = { | |
2044 | + .read = generic_read_dir, | |
2045 | + .open = ovl_dir_open, | |
392086de | 2046 | + .iterate = ovl_iterate, |
68184a5a JR |
2047 | + .llseek = ovl_dir_llseek, |
2048 | + .fsync = ovl_dir_fsync, | |
2049 | + .release = ovl_dir_release, | |
2050 | +}; | |
2051 | + | |
2052 | +static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) | |
2053 | +{ | |
2054 | + int err; | |
2055 | + struct path lowerpath; | |
2056 | + struct path upperpath; | |
2057 | + struct ovl_cache_entry *p; | |
68184a5a JR |
2058 | + |
2059 | + ovl_path_upper(dentry, &upperpath); | |
2060 | + ovl_path_lower(dentry, &lowerpath); | |
2061 | + | |
392086de | 2062 | + err = ovl_dir_read_merged(&upperpath, &lowerpath, list); |
68184a5a JR |
2063 | + if (err) |
2064 | + return err; | |
2065 | + | |
2066 | + err = 0; | |
2067 | + | |
2068 | + list_for_each_entry(p, list, l_node) { | |
2069 | + if (p->is_whiteout) | |
2070 | + continue; | |
2071 | + | |
2072 | + if (p->name[0] == '.') { | |
2073 | + if (p->len == 1) | |
2074 | + continue; | |
2075 | + if (p->len == 2 && p->name[1] == '.') | |
2076 | + continue; | |
2077 | + } | |
2078 | + err = -ENOTEMPTY; | |
2079 | + break; | |
2080 | + } | |
2081 | + | |
2082 | + return err; | |
2083 | +} | |
2084 | + | |
2085 | +static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list) | |
2086 | +{ | |
2087 | + struct path upperpath; | |
2088 | + struct dentry *upperdir; | |
2089 | + struct ovl_cache_entry *p; | |
2090 | + const struct cred *old_cred; | |
2091 | + struct cred *override_cred; | |
2092 | + int err; | |
2093 | + | |
2094 | + ovl_path_upper(dir, &upperpath); | |
2095 | + upperdir = upperpath.dentry; | |
2096 | + | |
2097 | + override_cred = prepare_creds(); | |
2098 | + if (!override_cred) | |
2099 | + return -ENOMEM; | |
2100 | + | |
2101 | + /* | |
2102 | + * CAP_DAC_OVERRIDE for lookup and unlink | |
2103 | + * CAP_SYS_ADMIN for setxattr of "trusted" namespace | |
2104 | + * CAP_FOWNER for unlink in sticky directory | |
2105 | + */ | |
2106 | + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
2107 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
2108 | + cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
2109 | + old_cred = override_creds(override_cred); | |
2110 | + | |
2111 | + err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0); | |
2112 | + if (err) | |
2113 | + goto out_revert_creds; | |
2114 | + | |
2115 | + mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); | |
2116 | + list_for_each_entry(p, list, l_node) { | |
2117 | + struct dentry *dentry; | |
2118 | + int ret; | |
2119 | + | |
2120 | + if (!p->is_whiteout) | |
2121 | + continue; | |
2122 | + | |
2123 | + dentry = lookup_one_len(p->name, upperdir, p->len); | |
2124 | + if (IS_ERR(dentry)) { | |
c06a8ce3 | 2125 | + pr_warn( |
68184a5a JR |
2126 | + "overlayfs: failed to lookup whiteout %.*s: %li\n", |
2127 | + p->len, p->name, PTR_ERR(dentry)); | |
2128 | + continue; | |
2129 | + } | |
a25ec4e9 | 2130 | + ret = vfs_unlink(upperdir->d_inode, dentry, NULL); |
68184a5a JR |
2131 | + dput(dentry); |
2132 | + if (ret) | |
c06a8ce3 | 2133 | + pr_warn( |
68184a5a JR |
2134 | + "overlayfs: failed to unlink whiteout %.*s: %i\n", |
2135 | + p->len, p->name, ret); | |
2136 | + } | |
2137 | + mutex_unlock(&upperdir->d_inode->i_mutex); | |
2138 | + | |
2139 | +out_revert_creds: | |
2140 | + revert_creds(old_cred); | |
2141 | + put_cred(override_cred); | |
2142 | + | |
2143 | + return err; | |
2144 | +} | |
2145 | + | |
2146 | +int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type) | |
2147 | +{ | |
2148 | + int err; | |
2149 | + LIST_HEAD(list); | |
2150 | + | |
2151 | + err = ovl_check_empty_dir(dentry, &list); | |
2152 | + if (!err && type == OVL_PATH_MERGE) | |
2153 | + err = ovl_remove_whiteouts(dentry, &list); | |
2154 | + | |
2155 | + ovl_cache_free(&list); | |
2156 | + | |
2157 | + return err; | |
2158 | +} | |
514e5dae AM |
2159 | --- /dev/null |
2160 | +++ b/fs/overlayfs/super.c | |
c06a8ce3 | 2161 | @@ -0,0 +1,612 @@ |
68184a5a JR |
2162 | +/* |
2163 | + * | |
2164 | + * Copyright (C) 2011 Novell Inc. | |
2165 | + * | |
2166 | + * This program is free software; you can redistribute it and/or modify it | |
2167 | + * under the terms of the GNU General Public License version 2 as published by | |
2168 | + * the Free Software Foundation. | |
2169 | + */ | |
2170 | + | |
2171 | +#include <linux/fs.h> | |
2172 | +#include <linux/namei.h> | |
2173 | +#include <linux/xattr.h> | |
2174 | +#include <linux/security.h> | |
2175 | +#include <linux/mount.h> | |
2176 | +#include <linux/slab.h> | |
2177 | +#include <linux/parser.h> | |
2178 | +#include <linux/module.h> | |
2179 | +#include <linux/cred.h> | |
2180 | +#include <linux/sched.h> | |
2181 | +#include "overlayfs.h" | |
2182 | + | |
2183 | +MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); | |
2184 | +MODULE_DESCRIPTION("Overlay filesystem"); | |
2185 | +MODULE_LICENSE("GPL"); | |
2186 | + | |
2187 | +struct ovl_fs { | |
2188 | + struct vfsmount *upper_mnt; | |
2189 | + struct vfsmount *lower_mnt; | |
2190 | +}; | |
2191 | + | |
2192 | +struct ovl_entry { | |
2193 | + /* | |
2194 | + * Keep "double reference" on upper dentries, so that | |
2195 | + * d_delete() doesn't think it's OK to reset d_inode to NULL. | |
2196 | + */ | |
2197 | + struct dentry *__upperdentry; | |
2198 | + struct dentry *lowerdentry; | |
2199 | + union { | |
2200 | + struct { | |
2201 | + u64 version; | |
2202 | + bool opaque; | |
2203 | + }; | |
2204 | + struct rcu_head rcu; | |
2205 | + }; | |
2206 | +}; | |
2207 | + | |
2208 | +const char *ovl_whiteout_xattr = "trusted.overlay.whiteout"; | |
2209 | +const char *ovl_opaque_xattr = "trusted.overlay.opaque"; | |
2210 | + | |
2211 | + | |
2212 | +enum ovl_path_type ovl_path_type(struct dentry *dentry) | |
2213 | +{ | |
2214 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2215 | + | |
2216 | + if (oe->__upperdentry) { | |
2217 | + if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode)) | |
2218 | + return OVL_PATH_MERGE; | |
2219 | + else | |
2220 | + return OVL_PATH_UPPER; | |
2221 | + } else { | |
2222 | + return OVL_PATH_LOWER; | |
2223 | + } | |
2224 | +} | |
2225 | + | |
2226 | +static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) | |
2227 | +{ | |
2228 | + struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry); | |
2229 | + smp_read_barrier_depends(); | |
2230 | + return upperdentry; | |
2231 | +} | |
2232 | + | |
2233 | +void ovl_path_upper(struct dentry *dentry, struct path *path) | |
2234 | +{ | |
2235 | + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
2236 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2237 | + | |
2238 | + path->mnt = ofs->upper_mnt; | |
2239 | + path->dentry = ovl_upperdentry_dereference(oe); | |
2240 | +} | |
2241 | + | |
2242 | +void ovl_path_lower(struct dentry *dentry, struct path *path) | |
2243 | +{ | |
2244 | + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
2245 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2246 | + | |
2247 | + path->mnt = ofs->lower_mnt; | |
2248 | + path->dentry = oe->lowerdentry; | |
2249 | +} | |
2250 | + | |
2251 | +enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) | |
2252 | +{ | |
2253 | + | |
2254 | + enum ovl_path_type type = ovl_path_type(dentry); | |
2255 | + | |
2256 | + if (type == OVL_PATH_LOWER) | |
2257 | + ovl_path_lower(dentry, path); | |
2258 | + else | |
2259 | + ovl_path_upper(dentry, path); | |
2260 | + | |
2261 | + return type; | |
2262 | +} | |
2263 | + | |
2264 | +struct dentry *ovl_dentry_upper(struct dentry *dentry) | |
2265 | +{ | |
2266 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2267 | + | |
2268 | + return ovl_upperdentry_dereference(oe); | |
2269 | +} | |
2270 | + | |
2271 | +struct dentry *ovl_dentry_lower(struct dentry *dentry) | |
2272 | +{ | |
2273 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2274 | + | |
2275 | + return oe->lowerdentry; | |
2276 | +} | |
2277 | + | |
2278 | +struct dentry *ovl_dentry_real(struct dentry *dentry) | |
2279 | +{ | |
2280 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2281 | + struct dentry *realdentry; | |
2282 | + | |
2283 | + realdentry = ovl_upperdentry_dereference(oe); | |
2284 | + if (!realdentry) | |
2285 | + realdentry = oe->lowerdentry; | |
2286 | + | |
2287 | + return realdentry; | |
2288 | +} | |
2289 | + | |
2290 | +struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper) | |
2291 | +{ | |
2292 | + struct dentry *realdentry; | |
2293 | + | |
2294 | + realdentry = ovl_upperdentry_dereference(oe); | |
2295 | + if (realdentry) { | |
2296 | + *is_upper = true; | |
2297 | + } else { | |
2298 | + realdentry = oe->lowerdentry; | |
2299 | + *is_upper = false; | |
2300 | + } | |
2301 | + return realdentry; | |
2302 | +} | |
2303 | + | |
2304 | +bool ovl_dentry_is_opaque(struct dentry *dentry) | |
2305 | +{ | |
2306 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2307 | + return oe->opaque; | |
2308 | +} | |
2309 | + | |
2310 | +void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) | |
2311 | +{ | |
2312 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2313 | + oe->opaque = opaque; | |
2314 | +} | |
2315 | + | |
2316 | +void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) | |
2317 | +{ | |
2318 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2319 | + | |
2320 | + WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex)); | |
2321 | + WARN_ON(oe->__upperdentry); | |
2322 | + BUG_ON(!upperdentry->d_inode); | |
2323 | + smp_wmb(); | |
2324 | + oe->__upperdentry = dget(upperdentry); | |
2325 | +} | |
2326 | + | |
2327 | +void ovl_dentry_version_inc(struct dentry *dentry) | |
2328 | +{ | |
2329 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2330 | + | |
2331 | + WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
2332 | + oe->version++; | |
2333 | +} | |
2334 | + | |
2335 | +u64 ovl_dentry_version_get(struct dentry *dentry) | |
2336 | +{ | |
2337 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2338 | + | |
2339 | + WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
2340 | + return oe->version; | |
2341 | +} | |
2342 | + | |
2343 | +bool ovl_is_whiteout(struct dentry *dentry) | |
2344 | +{ | |
2345 | + int res; | |
2346 | + char val; | |
2347 | + | |
2348 | + if (!dentry) | |
2349 | + return false; | |
2350 | + if (!dentry->d_inode) | |
2351 | + return false; | |
2352 | + if (!S_ISLNK(dentry->d_inode->i_mode)) | |
2353 | + return false; | |
2354 | + | |
2355 | + res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1); | |
2356 | + if (res == 1 && val == 'y') | |
2357 | + return true; | |
2358 | + | |
2359 | + return false; | |
2360 | +} | |
2361 | + | |
2362 | +static bool ovl_is_opaquedir(struct dentry *dentry) | |
2363 | +{ | |
2364 | + int res; | |
2365 | + char val; | |
2366 | + | |
2367 | + if (!S_ISDIR(dentry->d_inode->i_mode)) | |
2368 | + return false; | |
2369 | + | |
2370 | + res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1); | |
2371 | + if (res == 1 && val == 'y') | |
2372 | + return true; | |
2373 | + | |
2374 | + return false; | |
2375 | +} | |
2376 | + | |
2377 | +static void ovl_entry_free(struct rcu_head *head) | |
2378 | +{ | |
2379 | + struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu); | |
2380 | + kfree(oe); | |
2381 | +} | |
2382 | + | |
2383 | +static void ovl_dentry_release(struct dentry *dentry) | |
2384 | +{ | |
2385 | + struct ovl_entry *oe = dentry->d_fsdata; | |
2386 | + | |
2387 | + if (oe) { | |
2388 | + dput(oe->__upperdentry); | |
2389 | + dput(oe->__upperdentry); | |
2390 | + dput(oe->lowerdentry); | |
2391 | + call_rcu(&oe->rcu, ovl_entry_free); | |
2392 | + } | |
2393 | +} | |
2394 | + | |
2395 | +const struct dentry_operations ovl_dentry_operations = { | |
2396 | + .d_release = ovl_dentry_release, | |
2397 | +}; | |
2398 | + | |
2399 | +static struct ovl_entry *ovl_alloc_entry(void) | |
2400 | +{ | |
2401 | + return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL); | |
2402 | +} | |
2403 | + | |
2404 | +static inline struct dentry *ovl_lookup_real(struct dentry *dir, | |
2405 | + struct qstr *name) | |
2406 | +{ | |
2407 | + struct dentry *dentry; | |
2408 | + | |
2409 | + mutex_lock(&dir->d_inode->i_mutex); | |
2410 | + dentry = lookup_one_len(name->name, dir, name->len); | |
2411 | + mutex_unlock(&dir->d_inode->i_mutex); | |
2412 | + | |
2413 | + if (IS_ERR(dentry)) { | |
2414 | + if (PTR_ERR(dentry) == -ENOENT) | |
2415 | + dentry = NULL; | |
2416 | + } else if (!dentry->d_inode) { | |
2417 | + dput(dentry); | |
2418 | + dentry = NULL; | |
2419 | + } | |
2420 | + return dentry; | |
2421 | +} | |
2422 | + | |
2423 | +static int ovl_do_lookup(struct dentry *dentry) | |
2424 | +{ | |
2425 | + struct ovl_entry *oe; | |
2426 | + struct dentry *upperdir; | |
2427 | + struct dentry *lowerdir; | |
2428 | + struct dentry *upperdentry = NULL; | |
2429 | + struct dentry *lowerdentry = NULL; | |
2430 | + struct inode *inode = NULL; | |
2431 | + int err; | |
2432 | + | |
2433 | + err = -ENOMEM; | |
2434 | + oe = ovl_alloc_entry(); | |
2435 | + if (!oe) | |
2436 | + goto out; | |
2437 | + | |
2438 | + upperdir = ovl_dentry_upper(dentry->d_parent); | |
2439 | + lowerdir = ovl_dentry_lower(dentry->d_parent); | |
2440 | + | |
2441 | + if (upperdir) { | |
2442 | + upperdentry = ovl_lookup_real(upperdir, &dentry->d_name); | |
2443 | + err = PTR_ERR(upperdentry); | |
2444 | + if (IS_ERR(upperdentry)) | |
2445 | + goto out_put_dir; | |
2446 | + | |
2447 | + if (lowerdir && upperdentry && | |
2448 | + (S_ISLNK(upperdentry->d_inode->i_mode) || | |
2449 | + S_ISDIR(upperdentry->d_inode->i_mode))) { | |
2450 | + const struct cred *old_cred; | |
2451 | + struct cred *override_cred; | |
2452 | + | |
2453 | + err = -ENOMEM; | |
2454 | + override_cred = prepare_creds(); | |
2455 | + if (!override_cred) | |
2456 | + goto out_dput_upper; | |
2457 | + | |
2458 | + /* CAP_SYS_ADMIN needed for getxattr */ | |
2459 | + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
2460 | + old_cred = override_creds(override_cred); | |
2461 | + | |
2462 | + if (ovl_is_opaquedir(upperdentry)) { | |
2463 | + oe->opaque = true; | |
2464 | + } else if (ovl_is_whiteout(upperdentry)) { | |
2465 | + dput(upperdentry); | |
2466 | + upperdentry = NULL; | |
2467 | + oe->opaque = true; | |
2468 | + } | |
2469 | + revert_creds(old_cred); | |
2470 | + put_cred(override_cred); | |
2471 | + } | |
2472 | + } | |
2473 | + if (lowerdir && !oe->opaque) { | |
2474 | + lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name); | |
2475 | + err = PTR_ERR(lowerdentry); | |
2476 | + if (IS_ERR(lowerdentry)) | |
2477 | + goto out_dput_upper; | |
2478 | + } | |
2479 | + | |
2480 | + if (lowerdentry && upperdentry && | |
2481 | + (!S_ISDIR(upperdentry->d_inode->i_mode) || | |
2482 | + !S_ISDIR(lowerdentry->d_inode->i_mode))) { | |
2483 | + dput(lowerdentry); | |
2484 | + lowerdentry = NULL; | |
2485 | + oe->opaque = true; | |
2486 | + } | |
2487 | + | |
2488 | + if (lowerdentry || upperdentry) { | |
2489 | + struct dentry *realdentry; | |
2490 | + | |
2491 | + realdentry = upperdentry ? upperdentry : lowerdentry; | |
2492 | + err = -ENOMEM; | |
2493 | + inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode, | |
2494 | + oe); | |
2495 | + if (!inode) | |
2496 | + goto out_dput; | |
c06a8ce3 | 2497 | + ovl_copyattr(realdentry->d_inode, inode); |
68184a5a JR |
2498 | + } |
2499 | + | |
2500 | + if (upperdentry) | |
2501 | + oe->__upperdentry = dget(upperdentry); | |
2502 | + | |
2503 | + if (lowerdentry) | |
2504 | + oe->lowerdentry = lowerdentry; | |
2505 | + | |
2506 | + dentry->d_fsdata = oe; | |
2507 | + dentry->d_op = &ovl_dentry_operations; | |
2508 | + d_add(dentry, inode); | |
2509 | + | |
2510 | + return 0; | |
2511 | + | |
2512 | +out_dput: | |
2513 | + dput(lowerdentry); | |
2514 | +out_dput_upper: | |
2515 | + dput(upperdentry); | |
2516 | +out_put_dir: | |
2517 | + kfree(oe); | |
2518 | +out: | |
2519 | + return err; | |
2520 | +} | |
2521 | + | |
2522 | +struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, | |
2523 | + unsigned int flags) | |
2524 | +{ | |
2525 | + int err = ovl_do_lookup(dentry); | |
2526 | + | |
2527 | + if (err) | |
2528 | + return ERR_PTR(err); | |
2529 | + | |
2530 | + return NULL; | |
2531 | +} | |
2532 | + | |
2533 | +struct file *ovl_path_open(struct path *path, int flags) | |
2534 | +{ | |
68184a5a JR |
2535 | + return dentry_open(path, flags, current_cred()); |
2536 | +} | |
2537 | + | |
2538 | +static void ovl_put_super(struct super_block *sb) | |
2539 | +{ | |
2540 | + struct ovl_fs *ufs = sb->s_fs_info; | |
2541 | + | |
2542 | + if (!(sb->s_flags & MS_RDONLY)) | |
2543 | + mnt_drop_write(ufs->upper_mnt); | |
2544 | + | |
2545 | + mntput(ufs->upper_mnt); | |
2546 | + mntput(ufs->lower_mnt); | |
2547 | + | |
2548 | + kfree(ufs); | |
2549 | +} | |
2550 | + | |
2551 | +static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data) | |
2552 | +{ | |
2553 | + int flags = *flagsp; | |
2554 | + struct ovl_fs *ufs = sb->s_fs_info; | |
2555 | + | |
2556 | + /* When remounting rw or ro, we need to adjust the write access to the | |
2557 | + * upper fs. | |
2558 | + */ | |
2559 | + if (((flags ^ sb->s_flags) & MS_RDONLY) == 0) | |
2560 | + /* No change to readonly status */ | |
2561 | + return 0; | |
2562 | + | |
2563 | + if (flags & MS_RDONLY) { | |
2564 | + mnt_drop_write(ufs->upper_mnt); | |
2565 | + return 0; | |
2566 | + } else | |
2567 | + return mnt_want_write(ufs->upper_mnt); | |
2568 | +} | |
2569 | + | |
2570 | +static const struct super_operations ovl_super_operations = { | |
2571 | + .put_super = ovl_put_super, | |
2572 | + .remount_fs = ovl_remount_fs, | |
2573 | +}; | |
2574 | + | |
2575 | +struct ovl_config { | |
2576 | + char *lowerdir; | |
2577 | + char *upperdir; | |
2578 | +}; | |
2579 | + | |
2580 | +enum { | |
c06a8ce3 AM |
2581 | + OPT_LOWERDIR, |
2582 | + OPT_UPPERDIR, | |
2583 | + OPT_ERR, | |
68184a5a JR |
2584 | +}; |
2585 | + | |
2586 | +static const match_table_t ovl_tokens = { | |
c06a8ce3 AM |
2587 | + {OPT_LOWERDIR, "lowerdir=%s"}, |
2588 | + {OPT_UPPERDIR, "upperdir=%s"}, | |
2589 | + {OPT_ERR, NULL} | |
68184a5a JR |
2590 | +}; |
2591 | + | |
2592 | +static int ovl_parse_opt(char *opt, struct ovl_config *config) | |
2593 | +{ | |
2594 | + char *p; | |
2595 | + | |
2596 | + config->upperdir = NULL; | |
2597 | + config->lowerdir = NULL; | |
2598 | + | |
2599 | + while ((p = strsep(&opt, ",")) != NULL) { | |
2600 | + int token; | |
2601 | + substring_t args[MAX_OPT_ARGS]; | |
2602 | + | |
2603 | + if (!*p) | |
2604 | + continue; | |
2605 | + | |
2606 | + token = match_token(p, ovl_tokens, args); | |
2607 | + switch (token) { | |
c06a8ce3 | 2608 | + case OPT_UPPERDIR: |
68184a5a JR |
2609 | + kfree(config->upperdir); |
2610 | + config->upperdir = match_strdup(&args[0]); | |
2611 | + if (!config->upperdir) | |
2612 | + return -ENOMEM; | |
2613 | + break; | |
2614 | + | |
c06a8ce3 | 2615 | + case OPT_LOWERDIR: |
68184a5a JR |
2616 | + kfree(config->lowerdir); |
2617 | + config->lowerdir = match_strdup(&args[0]); | |
2618 | + if (!config->lowerdir) | |
2619 | + return -ENOMEM; | |
2620 | + break; | |
2621 | + | |
2622 | + default: | |
2623 | + return -EINVAL; | |
2624 | + } | |
2625 | + } | |
2626 | + return 0; | |
2627 | +} | |
2628 | + | |
2629 | +static int ovl_fill_super(struct super_block *sb, void *data, int silent) | |
2630 | +{ | |
2631 | + struct path lowerpath; | |
2632 | + struct path upperpath; | |
2633 | + struct inode *root_inode; | |
2634 | + struct dentry *root_dentry; | |
2635 | + struct ovl_entry *oe; | |
2636 | + struct ovl_fs *ufs; | |
2637 | + struct ovl_config config; | |
2638 | + int err; | |
2639 | + | |
2640 | + err = ovl_parse_opt((char *) data, &config); | |
2641 | + if (err) | |
2642 | + goto out; | |
2643 | + | |
2644 | + err = -EINVAL; | |
2645 | + if (!config.upperdir || !config.lowerdir) { | |
c06a8ce3 | 2646 | + pr_err("overlayfs: missing upperdir or lowerdir\n"); |
68184a5a JR |
2647 | + goto out_free_config; |
2648 | + } | |
2649 | + | |
2650 | + err = -ENOMEM; | |
2651 | + ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL); | |
2652 | + if (!ufs) | |
2653 | + goto out_free_config; | |
2654 | + | |
2655 | + oe = ovl_alloc_entry(); | |
2656 | + if (oe == NULL) | |
2657 | + goto out_free_ufs; | |
2658 | + | |
2659 | + err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath); | |
2660 | + if (err) | |
2661 | + goto out_free_oe; | |
2662 | + | |
2663 | + err = kern_path(config.lowerdir, LOOKUP_FOLLOW, &lowerpath); | |
2664 | + if (err) | |
2665 | + goto out_put_upperpath; | |
2666 | + | |
2667 | + err = -ENOTDIR; | |
2668 | + if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) || | |
2669 | + !S_ISDIR(lowerpath.dentry->d_inode->i_mode)) | |
2670 | + goto out_put_lowerpath; | |
2671 | + | |
2672 | + ufs->upper_mnt = clone_private_mount(&upperpath); | |
2673 | + err = PTR_ERR(ufs->upper_mnt); | |
2674 | + if (IS_ERR(ufs->upper_mnt)) { | |
c06a8ce3 | 2675 | + pr_err("overlayfs: failed to clone upperpath\n"); |
68184a5a JR |
2676 | + goto out_put_lowerpath; |
2677 | + } | |
2678 | + | |
2679 | + ufs->lower_mnt = clone_private_mount(&lowerpath); | |
2680 | + err = PTR_ERR(ufs->lower_mnt); | |
2681 | + if (IS_ERR(ufs->lower_mnt)) { | |
c06a8ce3 | 2682 | + pr_err("overlayfs: failed to clone lowerpath\n"); |
68184a5a JR |
2683 | + goto out_put_upper_mnt; |
2684 | + } | |
2685 | + | |
2686 | + /* | |
2687 | + * Make lower_mnt R/O. That way fchmod/fchown on lower file | |
2688 | + * will fail instead of modifying lower fs. | |
2689 | + */ | |
2690 | + ufs->lower_mnt->mnt_flags |= MNT_READONLY; | |
2691 | + | |
2692 | + /* If the upper fs is r/o, we mark overlayfs r/o too */ | |
2693 | + if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY) | |
2694 | + sb->s_flags |= MS_RDONLY; | |
2695 | + | |
2696 | + if (!(sb->s_flags & MS_RDONLY)) { | |
2697 | + err = mnt_want_write(ufs->upper_mnt); | |
2698 | + if (err) | |
2699 | + goto out_put_lower_mnt; | |
2700 | + } | |
2701 | + | |
2702 | + err = -ENOMEM; | |
2703 | + root_inode = ovl_new_inode(sb, S_IFDIR, oe); | |
2704 | + if (!root_inode) | |
2705 | + goto out_drop_write; | |
2706 | + | |
2707 | + root_dentry = d_make_root(root_inode); | |
2708 | + if (!root_dentry) | |
2709 | + goto out_drop_write; | |
2710 | + | |
2711 | + mntput(upperpath.mnt); | |
2712 | + mntput(lowerpath.mnt); | |
2713 | + | |
2714 | + oe->__upperdentry = dget(upperpath.dentry); | |
2715 | + oe->lowerdentry = lowerpath.dentry; | |
2716 | + | |
2717 | + root_dentry->d_fsdata = oe; | |
2718 | + root_dentry->d_op = &ovl_dentry_operations; | |
2719 | + | |
2720 | + sb->s_op = &ovl_super_operations; | |
2721 | + sb->s_root = root_dentry; | |
2722 | + sb->s_fs_info = ufs; | |
2723 | + | |
2724 | + return 0; | |
2725 | + | |
2726 | +out_drop_write: | |
2727 | + if (!(sb->s_flags & MS_RDONLY)) | |
2728 | + mnt_drop_write(ufs->upper_mnt); | |
2729 | +out_put_lower_mnt: | |
2730 | + mntput(ufs->lower_mnt); | |
2731 | +out_put_upper_mnt: | |
2732 | + mntput(ufs->upper_mnt); | |
2733 | +out_put_lowerpath: | |
2734 | + path_put(&lowerpath); | |
2735 | +out_put_upperpath: | |
2736 | + path_put(&upperpath); | |
2737 | +out_free_oe: | |
2738 | + kfree(oe); | |
2739 | +out_free_ufs: | |
2740 | + kfree(ufs); | |
2741 | +out_free_config: | |
2742 | + kfree(config.lowerdir); | |
2743 | + kfree(config.upperdir); | |
2744 | +out: | |
2745 | + return err; | |
2746 | +} | |
2747 | + | |
2748 | +static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
2749 | + const char *dev_name, void *raw_data) | |
2750 | +{ | |
2751 | + return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
2752 | +} | |
2753 | + | |
2754 | +static struct file_system_type ovl_fs_type = { | |
2755 | + .owner = THIS_MODULE, | |
2756 | + .name = "overlayfs", | |
2757 | + .mount = ovl_mount, | |
2758 | + .kill_sb = kill_anon_super, | |
2759 | +}; | |
c06a8ce3 | 2760 | +MODULE_ALIAS_FS("overlayfs"); |
68184a5a JR |
2761 | + |
2762 | +static int __init ovl_init(void) | |
2763 | +{ | |
2764 | + return register_filesystem(&ovl_fs_type); | |
2765 | +} | |
2766 | + | |
2767 | +static void __exit ovl_exit(void) | |
2768 | +{ | |
2769 | + unregister_filesystem(&ovl_fs_type); | |
2770 | +} | |
2771 | + | |
2772 | +module_init(ovl_init); | |
2773 | +module_exit(ovl_exit); |