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Commit | Line | Data |
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bbb1e54d MS |
1 | /* |
2 | * Copyright (C) 2011 Novell Inc. | |
3 | * Copyright (C) 2016 Red Hat, Inc. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License version 2 as published by | |
7 | * the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/fs.h> | |
11 | #include <linux/mount.h> | |
12 | #include <linux/slab.h> | |
5b825c3a | 13 | #include <linux/cred.h> |
bbb1e54d | 14 | #include <linux/xattr.h> |
02bcd157 AG |
15 | #include <linux/exportfs.h> |
16 | #include <linux/uuid.h> | |
caf70cb2 AG |
17 | #include <linux/namei.h> |
18 | #include <linux/ratelimit.h> | |
bbb1e54d | 19 | #include "overlayfs.h" |
bbb1e54d MS |
20 | |
21 | int ovl_want_write(struct dentry *dentry) | |
22 | { | |
23 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
24 | return mnt_want_write(ofs->upper_mnt); | |
25 | } | |
26 | ||
27 | void ovl_drop_write(struct dentry *dentry) | |
28 | { | |
29 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
30 | mnt_drop_write(ofs->upper_mnt); | |
31 | } | |
32 | ||
33 | struct dentry *ovl_workdir(struct dentry *dentry) | |
34 | { | |
35 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
36 | return ofs->workdir; | |
37 | } | |
38 | ||
39 | const struct cred *ovl_override_creds(struct super_block *sb) | |
40 | { | |
41 | struct ovl_fs *ofs = sb->s_fs_info; | |
42 | ||
43 | return override_creds(ofs->creator_cred); | |
44 | } | |
45 | ||
7bcd74b9 AG |
46 | struct super_block *ovl_same_sb(struct super_block *sb) |
47 | { | |
48 | struct ovl_fs *ofs = sb->s_fs_info; | |
49 | ||
50 | return ofs->same_sb; | |
51 | } | |
52 | ||
a0b09f9b AW |
53 | int ovl_creator_permission(struct super_block *sb, struct inode *inode, |
54 | int mode) | |
55 | { | |
56 | const struct cred *old_cred; | |
57 | int err = 0; | |
58 | ||
59 | old_cred = ovl_override_creds(sb); | |
60 | err = inode_permission(inode, mode); | |
61 | revert_creds(old_cred); | |
62 | ||
63 | return err; | |
64 | } | |
65 | ||
02bcd157 AG |
66 | bool ovl_can_decode_fh(struct super_block *sb) |
67 | { | |
68 | return (sb->s_export_op && sb->s_export_op->fh_to_dentry && | |
69 | !uuid_is_null(&sb->s_uuid)); | |
70 | } | |
71 | ||
72 | struct dentry *ovl_indexdir(struct super_block *sb) | |
73 | { | |
74 | struct ovl_fs *ofs = sb->s_fs_info; | |
75 | ||
76 | return ofs->indexdir; | |
77 | } | |
78 | ||
bbb1e54d MS |
79 | struct ovl_entry *ovl_alloc_entry(unsigned int numlower) |
80 | { | |
81 | size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); | |
82 | struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); | |
83 | ||
84 | if (oe) | |
85 | oe->numlower = numlower; | |
86 | ||
87 | return oe; | |
88 | } | |
89 | ||
90 | bool ovl_dentry_remote(struct dentry *dentry) | |
91 | { | |
92 | return dentry->d_flags & | |
93 | (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | | |
94 | DCACHE_OP_REAL); | |
95 | } | |
96 | ||
97 | bool ovl_dentry_weird(struct dentry *dentry) | |
98 | { | |
99 | return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | | |
100 | DCACHE_MANAGE_TRANSIT | | |
101 | DCACHE_OP_HASH | | |
102 | DCACHE_OP_COMPARE); | |
103 | } | |
104 | ||
105 | enum ovl_path_type ovl_path_type(struct dentry *dentry) | |
106 | { | |
107 | struct ovl_entry *oe = dentry->d_fsdata; | |
108 | enum ovl_path_type type = 0; | |
109 | ||
09d8b586 | 110 | if (ovl_dentry_upper(dentry)) { |
bbb1e54d MS |
111 | type = __OVL_PATH_UPPER; |
112 | ||
113 | /* | |
59548503 | 114 | * Non-dir dentry can hold lower dentry of its copy up origin. |
bbb1e54d | 115 | */ |
59548503 AG |
116 | if (oe->numlower) { |
117 | type |= __OVL_PATH_ORIGIN; | |
118 | if (d_is_dir(dentry)) | |
119 | type |= __OVL_PATH_MERGE; | |
120 | } | |
bbb1e54d MS |
121 | } else { |
122 | if (oe->numlower > 1) | |
123 | type |= __OVL_PATH_MERGE; | |
124 | } | |
125 | return type; | |
126 | } | |
127 | ||
128 | void ovl_path_upper(struct dentry *dentry, struct path *path) | |
129 | { | |
130 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
bbb1e54d MS |
131 | |
132 | path->mnt = ofs->upper_mnt; | |
09d8b586 | 133 | path->dentry = ovl_dentry_upper(dentry); |
bbb1e54d MS |
134 | } |
135 | ||
136 | void ovl_path_lower(struct dentry *dentry, struct path *path) | |
137 | { | |
138 | struct ovl_entry *oe = dentry->d_fsdata; | |
139 | ||
b9343632 CR |
140 | if (oe->numlower) { |
141 | path->mnt = oe->lowerstack[0].layer->mnt; | |
142 | path->dentry = oe->lowerstack[0].dentry; | |
143 | } else { | |
144 | *path = (struct path) { }; | |
145 | } | |
bbb1e54d MS |
146 | } |
147 | ||
148 | enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) | |
149 | { | |
150 | enum ovl_path_type type = ovl_path_type(dentry); | |
151 | ||
152 | if (!OVL_TYPE_UPPER(type)) | |
153 | ovl_path_lower(dentry, path); | |
154 | else | |
155 | ovl_path_upper(dentry, path); | |
156 | ||
157 | return type; | |
158 | } | |
159 | ||
160 | struct dentry *ovl_dentry_upper(struct dentry *dentry) | |
161 | { | |
09d8b586 | 162 | return ovl_upperdentry_dereference(OVL_I(d_inode(dentry))); |
bbb1e54d MS |
163 | } |
164 | ||
165 | struct dentry *ovl_dentry_lower(struct dentry *dentry) | |
166 | { | |
167 | struct ovl_entry *oe = dentry->d_fsdata; | |
168 | ||
09d8b586 | 169 | return oe->numlower ? oe->lowerstack[0].dentry : NULL; |
bbb1e54d MS |
170 | } |
171 | ||
172 | struct dentry *ovl_dentry_real(struct dentry *dentry) | |
173 | { | |
09d8b586 | 174 | return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry); |
bbb1e54d MS |
175 | } |
176 | ||
1d88f183 MS |
177 | struct dentry *ovl_i_dentry_upper(struct inode *inode) |
178 | { | |
179 | return ovl_upperdentry_dereference(OVL_I(inode)); | |
180 | } | |
181 | ||
09d8b586 | 182 | struct inode *ovl_inode_upper(struct inode *inode) |
25b7713a | 183 | { |
1d88f183 | 184 | struct dentry *upperdentry = ovl_i_dentry_upper(inode); |
25b7713a | 185 | |
09d8b586 MS |
186 | return upperdentry ? d_inode(upperdentry) : NULL; |
187 | } | |
25b7713a | 188 | |
09d8b586 MS |
189 | struct inode *ovl_inode_lower(struct inode *inode) |
190 | { | |
191 | return OVL_I(inode)->lower; | |
192 | } | |
25b7713a | 193 | |
09d8b586 MS |
194 | struct inode *ovl_inode_real(struct inode *inode) |
195 | { | |
196 | return ovl_inode_upper(inode) ?: ovl_inode_lower(inode); | |
25b7713a MS |
197 | } |
198 | ||
09d8b586 | 199 | |
4edb83bb | 200 | struct ovl_dir_cache *ovl_dir_cache(struct inode *inode) |
bbb1e54d | 201 | { |
4edb83bb | 202 | return OVL_I(inode)->cache; |
bbb1e54d MS |
203 | } |
204 | ||
4edb83bb | 205 | void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache) |
bbb1e54d | 206 | { |
4edb83bb | 207 | OVL_I(inode)->cache = cache; |
bbb1e54d MS |
208 | } |
209 | ||
210 | bool ovl_dentry_is_opaque(struct dentry *dentry) | |
211 | { | |
212 | struct ovl_entry *oe = dentry->d_fsdata; | |
213 | return oe->opaque; | |
214 | } | |
215 | ||
216 | bool ovl_dentry_is_whiteout(struct dentry *dentry) | |
217 | { | |
218 | return !dentry->d_inode && ovl_dentry_is_opaque(dentry); | |
219 | } | |
220 | ||
5cf5b477 | 221 | void ovl_dentry_set_opaque(struct dentry *dentry) |
bbb1e54d MS |
222 | { |
223 | struct ovl_entry *oe = dentry->d_fsdata; | |
5cf5b477 MS |
224 | |
225 | oe->opaque = true; | |
bbb1e54d MS |
226 | } |
227 | ||
55acc661 MS |
228 | /* |
229 | * For hard links it's possible for ovl_dentry_upper() to return positive, while | |
230 | * there's no actual upper alias for the inode. Copy up code needs to know | |
231 | * about the existence of the upper alias, so it can't use ovl_dentry_upper(). | |
232 | */ | |
233 | bool ovl_dentry_has_upper_alias(struct dentry *dentry) | |
234 | { | |
235 | struct ovl_entry *oe = dentry->d_fsdata; | |
236 | ||
237 | return oe->has_upper; | |
238 | } | |
239 | ||
240 | void ovl_dentry_set_upper_alias(struct dentry *dentry) | |
241 | { | |
242 | struct ovl_entry *oe = dentry->d_fsdata; | |
243 | ||
244 | oe->has_upper = true; | |
245 | } | |
246 | ||
a6c60655 MS |
247 | bool ovl_redirect_dir(struct super_block *sb) |
248 | { | |
249 | struct ovl_fs *ofs = sb->s_fs_info; | |
250 | ||
21a22878 | 251 | return ofs->config.redirect_dir && !ofs->noxattr; |
a6c60655 MS |
252 | } |
253 | ||
254 | const char *ovl_dentry_get_redirect(struct dentry *dentry) | |
255 | { | |
cf31c463 | 256 | return OVL_I(d_inode(dentry))->redirect; |
a6c60655 MS |
257 | } |
258 | ||
259 | void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect) | |
260 | { | |
cf31c463 | 261 | struct ovl_inode *oi = OVL_I(d_inode(dentry)); |
a6c60655 | 262 | |
cf31c463 MS |
263 | kfree(oi->redirect); |
264 | oi->redirect = redirect; | |
a6c60655 MS |
265 | } |
266 | ||
09d8b586 MS |
267 | void ovl_inode_init(struct inode *inode, struct dentry *upperdentry, |
268 | struct dentry *lowerdentry) | |
bbb1e54d | 269 | { |
09d8b586 MS |
270 | if (upperdentry) |
271 | OVL_I(inode)->__upperdentry = upperdentry; | |
272 | if (lowerdentry) | |
d2c9584e | 273 | OVL_I(inode)->lower = igrab(d_inode(lowerdentry)); |
bbb1e54d | 274 | |
09d8b586 | 275 | ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode); |
bbb1e54d MS |
276 | } |
277 | ||
09d8b586 | 278 | void ovl_inode_update(struct inode *inode, struct dentry *upperdentry) |
bbb1e54d | 279 | { |
09d8b586 | 280 | struct inode *upperinode = d_inode(upperdentry); |
e6d2ebdd | 281 | |
09d8b586 MS |
282 | WARN_ON(OVL_I(inode)->__upperdentry); |
283 | ||
25b7713a | 284 | /* |
09d8b586 | 285 | * Make sure upperdentry is consistent before making it visible |
25b7713a MS |
286 | */ |
287 | smp_wmb(); | |
09d8b586 | 288 | OVL_I(inode)->__upperdentry = upperdentry; |
d2c9584e | 289 | if (inode_unhashed(inode)) { |
25b7713a | 290 | inode->i_private = upperinode; |
bbb1e54d | 291 | __insert_inode_hash(inode, (unsigned long) upperinode); |
25b7713a | 292 | } |
bbb1e54d MS |
293 | } |
294 | ||
4edb83bb | 295 | void ovl_dentry_version_inc(struct dentry *dentry, bool impurity) |
bbb1e54d | 296 | { |
04a01ac7 | 297 | struct inode *inode = d_inode(dentry); |
bbb1e54d | 298 | |
04a01ac7 | 299 | WARN_ON(!inode_is_locked(inode)); |
4edb83bb MS |
300 | /* |
301 | * Version is used by readdir code to keep cache consistent. For merge | |
302 | * dirs all changes need to be noted. For non-merge dirs, cache only | |
303 | * contains impure (ones which have been copied up and have origins) | |
304 | * entries, so only need to note changes to impure entries. | |
305 | */ | |
306 | if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity) | |
307 | OVL_I(inode)->version++; | |
bbb1e54d MS |
308 | } |
309 | ||
310 | u64 ovl_dentry_version_get(struct dentry *dentry) | |
311 | { | |
04a01ac7 | 312 | struct inode *inode = d_inode(dentry); |
bbb1e54d | 313 | |
04a01ac7 MS |
314 | WARN_ON(!inode_is_locked(inode)); |
315 | return OVL_I(inode)->version; | |
bbb1e54d MS |
316 | } |
317 | ||
318 | bool ovl_is_whiteout(struct dentry *dentry) | |
319 | { | |
320 | struct inode *inode = dentry->d_inode; | |
321 | ||
322 | return inode && IS_WHITEOUT(inode); | |
323 | } | |
324 | ||
325 | struct file *ovl_path_open(struct path *path, int flags) | |
326 | { | |
327 | return dentry_open(path, flags | O_NOATIME, current_cred()); | |
328 | } | |
39d3d60a AG |
329 | |
330 | int ovl_copy_up_start(struct dentry *dentry) | |
331 | { | |
a015dafc | 332 | struct ovl_inode *oi = OVL_I(d_inode(dentry)); |
39d3d60a AG |
333 | int err; |
334 | ||
a015dafc | 335 | err = mutex_lock_interruptible(&oi->lock); |
59be0971 | 336 | if (!err && ovl_dentry_has_upper_alias(dentry)) { |
a015dafc AG |
337 | err = 1; /* Already copied up */ |
338 | mutex_unlock(&oi->lock); | |
39d3d60a | 339 | } |
39d3d60a AG |
340 | |
341 | return err; | |
342 | } | |
343 | ||
344 | void ovl_copy_up_end(struct dentry *dentry) | |
345 | { | |
a015dafc | 346 | mutex_unlock(&OVL_I(d_inode(dentry))->lock); |
39d3d60a | 347 | } |
82b749b2 | 348 | |
b79e05aa AG |
349 | bool ovl_check_origin_xattr(struct dentry *dentry) |
350 | { | |
351 | int res; | |
352 | ||
353 | res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0); | |
354 | ||
355 | /* Zero size value means "copied up but origin unknown" */ | |
356 | if (res >= 0) | |
357 | return true; | |
358 | ||
359 | return false; | |
360 | } | |
361 | ||
f3a15685 AG |
362 | bool ovl_check_dir_xattr(struct dentry *dentry, const char *name) |
363 | { | |
364 | int res; | |
365 | char val; | |
366 | ||
367 | if (!d_is_dir(dentry)) | |
368 | return false; | |
369 | ||
370 | res = vfs_getxattr(dentry, name, &val, 1); | |
371 | if (res == 1 && val == 'y') | |
372 | return true; | |
373 | ||
374 | return false; | |
375 | } | |
376 | ||
82b749b2 AG |
377 | int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry, |
378 | const char *name, const void *value, size_t size, | |
379 | int xerr) | |
380 | { | |
381 | int err; | |
382 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
383 | ||
384 | if (ofs->noxattr) | |
385 | return xerr; | |
386 | ||
387 | err = ovl_do_setxattr(upperdentry, name, value, size, 0); | |
388 | ||
389 | if (err == -EOPNOTSUPP) { | |
390 | pr_warn("overlayfs: cannot set %s xattr on upper\n", name); | |
391 | ofs->noxattr = true; | |
392 | return xerr; | |
393 | } | |
394 | ||
395 | return err; | |
396 | } | |
f3a15685 AG |
397 | |
398 | int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry) | |
399 | { | |
400 | int err; | |
f3a15685 | 401 | |
13c72075 | 402 | if (ovl_test_flag(OVL_IMPURE, d_inode(dentry))) |
f3a15685 AG |
403 | return 0; |
404 | ||
405 | /* | |
406 | * Do not fail when upper doesn't support xattrs. | |
407 | * Upper inodes won't have origin nor redirect xattr anyway. | |
408 | */ | |
409 | err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE, | |
410 | "y", 1, 0); | |
411 | if (!err) | |
13c72075 | 412 | ovl_set_flag(OVL_IMPURE, d_inode(dentry)); |
f3a15685 AG |
413 | |
414 | return err; | |
415 | } | |
13c72075 MS |
416 | |
417 | void ovl_set_flag(unsigned long flag, struct inode *inode) | |
418 | { | |
419 | set_bit(flag, &OVL_I(inode)->flags); | |
420 | } | |
421 | ||
4edb83bb MS |
422 | void ovl_clear_flag(unsigned long flag, struct inode *inode) |
423 | { | |
424 | clear_bit(flag, &OVL_I(inode)->flags); | |
425 | } | |
426 | ||
13c72075 MS |
427 | bool ovl_test_flag(unsigned long flag, struct inode *inode) |
428 | { | |
429 | return test_bit(flag, &OVL_I(inode)->flags); | |
430 | } | |
ad0af710 AG |
431 | |
432 | /** | |
433 | * Caller must hold a reference to inode to prevent it from being freed while | |
434 | * it is marked inuse. | |
435 | */ | |
436 | bool ovl_inuse_trylock(struct dentry *dentry) | |
437 | { | |
438 | struct inode *inode = d_inode(dentry); | |
439 | bool locked = false; | |
440 | ||
441 | spin_lock(&inode->i_lock); | |
442 | if (!(inode->i_state & I_OVL_INUSE)) { | |
443 | inode->i_state |= I_OVL_INUSE; | |
444 | locked = true; | |
445 | } | |
446 | spin_unlock(&inode->i_lock); | |
447 | ||
448 | return locked; | |
449 | } | |
450 | ||
451 | void ovl_inuse_unlock(struct dentry *dentry) | |
452 | { | |
453 | if (dentry) { | |
454 | struct inode *inode = d_inode(dentry); | |
455 | ||
456 | spin_lock(&inode->i_lock); | |
457 | WARN_ON(!(inode->i_state & I_OVL_INUSE)); | |
458 | inode->i_state &= ~I_OVL_INUSE; | |
459 | spin_unlock(&inode->i_lock); | |
460 | } | |
461 | } | |
5f8415d6 | 462 | |
9f4ec904 | 463 | /* Caller must hold OVL_I(inode)->lock */ |
caf70cb2 AG |
464 | static void ovl_cleanup_index(struct dentry *dentry) |
465 | { | |
466 | struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode; | |
467 | struct dentry *lowerdentry = ovl_dentry_lower(dentry); | |
468 | struct dentry *upperdentry = ovl_dentry_upper(dentry); | |
469 | struct dentry *index = NULL; | |
470 | struct inode *inode; | |
5efeca49 | 471 | struct qstr name = { }; |
caf70cb2 AG |
472 | int err; |
473 | ||
474 | err = ovl_get_index_name(lowerdentry, &name); | |
475 | if (err) | |
476 | goto fail; | |
477 | ||
478 | inode = d_inode(upperdentry); | |
479 | if (inode->i_nlink != 1) { | |
480 | pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n", | |
481 | upperdentry, inode->i_ino, inode->i_nlink); | |
482 | /* | |
483 | * We either have a bug with persistent union nlink or a lower | |
484 | * hardlink was added while overlay is mounted. Adding a lower | |
485 | * hardlink and then unlinking all overlay hardlinks would drop | |
486 | * overlay nlink to zero before all upper inodes are unlinked. | |
487 | * As a safety measure, when that situation is detected, set | |
488 | * the overlay nlink to the index inode nlink minus one for the | |
489 | * index entry itself. | |
490 | */ | |
491 | set_nlink(d_inode(dentry), inode->i_nlink - 1); | |
492 | ovl_set_nlink_upper(dentry); | |
493 | goto out; | |
494 | } | |
495 | ||
496 | inode_lock_nested(dir, I_MUTEX_PARENT); | |
497 | /* TODO: whiteout instead of cleanup to block future open by handle */ | |
498 | index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len); | |
499 | err = PTR_ERR(index); | |
500 | if (!IS_ERR(index)) | |
501 | err = ovl_cleanup(dir, index); | |
9f4ec904 AG |
502 | else |
503 | index = NULL; | |
504 | ||
caf70cb2 AG |
505 | inode_unlock(dir); |
506 | if (err) | |
507 | goto fail; | |
508 | ||
509 | out: | |
5efeca49 | 510 | kfree(name.name); |
caf70cb2 AG |
511 | dput(index); |
512 | return; | |
513 | ||
514 | fail: | |
515 | pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err); | |
516 | goto out; | |
517 | } | |
518 | ||
5f8415d6 AG |
519 | /* |
520 | * Operations that change overlay inode and upper inode nlink need to be | |
521 | * synchronized with copy up for persistent nlink accounting. | |
522 | */ | |
523 | int ovl_nlink_start(struct dentry *dentry, bool *locked) | |
524 | { | |
525 | struct ovl_inode *oi = OVL_I(d_inode(dentry)); | |
526 | const struct cred *old_cred; | |
527 | int err; | |
528 | ||
529 | if (!d_inode(dentry) || d_is_dir(dentry)) | |
530 | return 0; | |
531 | ||
532 | /* | |
533 | * With inodes index is enabled, we store the union overlay nlink | |
534 | * in an xattr on the index inode. When whiting out lower hardlinks | |
535 | * we need to decrement the overlay persistent nlink, but before the | |
536 | * first copy up, we have no upper index inode to store the xattr. | |
537 | * | |
538 | * As a workaround, before whiteout/rename over of a lower hardlink, | |
539 | * copy up to create the upper index. Creating the upper index will | |
540 | * initialize the overlay nlink, so it could be dropped if unlink | |
541 | * or rename succeeds. | |
542 | * | |
543 | * TODO: implement metadata only index copy up when called with | |
544 | * ovl_copy_up_flags(dentry, O_PATH). | |
545 | */ | |
546 | if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) && | |
547 | d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) { | |
548 | err = ovl_copy_up(dentry); | |
549 | if (err) | |
550 | return err; | |
551 | } | |
552 | ||
553 | err = mutex_lock_interruptible(&oi->lock); | |
554 | if (err) | |
555 | return err; | |
556 | ||
557 | if (!ovl_test_flag(OVL_INDEX, d_inode(dentry))) | |
558 | goto out; | |
559 | ||
560 | old_cred = ovl_override_creds(dentry->d_sb); | |
561 | /* | |
562 | * The overlay inode nlink should be incremented/decremented IFF the | |
563 | * upper operation succeeds, along with nlink change of upper inode. | |
564 | * Therefore, before link/unlink/rename, we store the union nlink | |
565 | * value relative to the upper inode nlink in an upper inode xattr. | |
566 | */ | |
567 | err = ovl_set_nlink_upper(dentry); | |
568 | revert_creds(old_cred); | |
569 | ||
570 | out: | |
571 | if (err) | |
572 | mutex_unlock(&oi->lock); | |
573 | else | |
574 | *locked = true; | |
575 | ||
576 | return err; | |
577 | } | |
578 | ||
579 | void ovl_nlink_end(struct dentry *dentry, bool locked) | |
580 | { | |
caf70cb2 AG |
581 | if (locked) { |
582 | if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) && | |
583 | d_inode(dentry)->i_nlink == 0) { | |
584 | const struct cred *old_cred; | |
585 | ||
586 | old_cred = ovl_override_creds(dentry->d_sb); | |
587 | ovl_cleanup_index(dentry); | |
588 | revert_creds(old_cred); | |
589 | } | |
590 | ||
5f8415d6 | 591 | mutex_unlock(&OVL_I(d_inode(dentry))->lock); |
caf70cb2 | 592 | } |
5f8415d6 | 593 | } |
5820dc08 AG |
594 | |
595 | int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir) | |
596 | { | |
597 | /* Workdir should not be the same as upperdir */ | |
598 | if (workdir == upperdir) | |
599 | goto err; | |
600 | ||
601 | /* Workdir should not be subdir of upperdir and vice versa */ | |
602 | if (lock_rename(workdir, upperdir) != NULL) | |
603 | goto err_unlock; | |
604 | ||
605 | return 0; | |
606 | ||
607 | err_unlock: | |
608 | unlock_rename(workdir, upperdir); | |
609 | err: | |
610 | pr_err("overlayfs: failed to lock workdir+upperdir\n"); | |
611 | return -EIO; | |
612 | } |