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libceph: introduce and switch to reopen_session()
[linux-2.6-block.git] / fs / overlayfs / dir.c
CommitLineData
e9be9d5e
MS		 1/*
2 *
3 * Copyright (C) 2011 Novell 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/namei.h>
12#include <linux/xattr.h>
13#include <linux/security.h>
14#include <linux/cred.h>
15#include "overlayfs.h"
16
17void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
18{
19 int err;
20
21 dget(wdentry);
e36cb0b8 22 if (d_is_dir(wdentry))
e9be9d5e
MS		 23 err = ovl_do_rmdir(wdir, wdentry);
24 else
25 err = ovl_do_unlink(wdir, wdentry);
26 dput(wdentry);
27
28 if (err) {
29 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
30 wdentry, err);
31 }
32}
33
34struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
35{
36 struct dentry *temp;
37 char name[20];
38
39 snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
40
41 temp = lookup_one_len(name, workdir, strlen(name));
42 if (!IS_ERR(temp) && temp->d_inode) {
43 pr_err("overlayfs: workdir/%s already exists\n", name);
44 dput(temp);
45 temp = ERR_PTR(-EIO);
46 }
47
48 return temp;
49}
50
51/* caller holds i_mutex on workdir */
52static struct dentry *ovl_whiteout(struct dentry *workdir,
53 struct dentry *dentry)
54{
55 int err;
56 struct dentry *whiteout;
57 struct inode *wdir = workdir->d_inode;
58
59 whiteout = ovl_lookup_temp(workdir, dentry);
60 if (IS_ERR(whiteout))
61 return whiteout;
62
63 err = ovl_do_whiteout(wdir, whiteout);
64 if (err) {
65 dput(whiteout);
66 whiteout = ERR_PTR(err);
67 }
68
69 return whiteout;
70}
71
72int ovl_create_real(struct inode *dir, struct dentry *newdentry,
73 struct kstat *stat, const char *link,
74 struct dentry *hardlink, bool debug)
75{
76 int err;
77
78 if (newdentry->d_inode)
79 return -ESTALE;
80
81 if (hardlink) {
82 err = ovl_do_link(hardlink, dir, newdentry, debug);
83 } else {
84 switch (stat->mode & S_IFMT) {
85 case S_IFREG:
86 err = ovl_do_create(dir, newdentry, stat->mode, debug);
87 break;
88
89 case S_IFDIR:
90 err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
91 break;
92
93 case S_IFCHR:
94 case S_IFBLK:
95 case S_IFIFO:
96 case S_IFSOCK:
97 err = ovl_do_mknod(dir, newdentry,
98 stat->mode, stat->rdev, debug);
99 break;
100
101 case S_IFLNK:
102 err = ovl_do_symlink(dir, newdentry, link, debug);
103 break;
104
105 default:
106 err = -EPERM;
107 }
108 }
109 if (!err && WARN_ON(!newdentry->d_inode)) {
110 /*
111 * Not quite sure if non-instantiated dentry is legal or not.
112 * VFS doesn't seem to care so check and warn here.
113 */
114 err = -ENOENT;
115 }
116 return err;
117}
118
119static int ovl_set_opaque(struct dentry *upperdentry)
120{
cead89bb 121 return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
e9be9d5e
MS		 122}
123
124static void ovl_remove_opaque(struct dentry *upperdentry)
125{
126 int err;
127
cead89bb 128 err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
e9be9d5e
MS		 129 if (err) {
130 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
131 upperdentry->d_name.name, err);
132 }
133}
134
135static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
136 struct kstat *stat)
137{
138 int err;
139 enum ovl_path_type type;
140 struct path realpath;
141
142 type = ovl_path_real(dentry, &realpath);
143 err = vfs_getattr(&realpath, stat);
144 if (err)
145 return err;
146
147 stat->dev = dentry->d_sb->s_dev;
148 stat->ino = dentry->d_inode->i_ino;
149
150 /*
151 * It's probably not worth it to count subdirs to get the
152 * correct link count. nlink=1 seems to pacify 'find' and
153 * other utilities.
154 */
1afaba1e 155 if (OVL_TYPE_MERGE(type))
e9be9d5e
MS		 156 stat->nlink = 1;
157
158 return 0;
159}
160
161static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
162 struct kstat *stat, const char *link,
163 struct dentry *hardlink)
164{
165 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
166 struct inode *udir = upperdir->d_inode;
167 struct dentry *newdentry;
168 int err;
169
5955102c 170 inode_lock_nested(udir, I_MUTEX_PARENT);
e9be9d5e
MS		 171 newdentry = lookup_one_len(dentry->d_name.name, upperdir,
172 dentry->d_name.len);
173 err = PTR_ERR(newdentry);
174 if (IS_ERR(newdentry))
175 goto out_unlock;
176 err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
177 if (err)
178 goto out_dput;
179
180 ovl_dentry_version_inc(dentry->d_parent);
181 ovl_dentry_update(dentry, newdentry);
182 ovl_copyattr(newdentry->d_inode, inode);
183 d_instantiate(dentry, inode);
184 newdentry = NULL;
185out_dput:
186 dput(newdentry);
187out_unlock:
5955102c 188 inode_unlock(udir);
e9be9d5e
MS		 189 return err;
190}
191
192static int ovl_lock_rename_workdir(struct dentry *workdir,
193 struct dentry *upperdir)
194{
195 /* Workdir should not be the same as upperdir */
196 if (workdir == upperdir)
197 goto err;
198
199 /* Workdir should not be subdir of upperdir and vice versa */
200 if (lock_rename(workdir, upperdir) != NULL)
201 goto err_unlock;
202
203 return 0;
204
205err_unlock:
206 unlock_rename(workdir, upperdir);
207err:
208 pr_err("overlayfs: failed to lock workdir+upperdir\n");
209 return -EIO;
210}
211
212static struct dentry *ovl_clear_empty(struct dentry *dentry,
213 struct list_head *list)
214{
215 struct dentry *workdir = ovl_workdir(dentry);
216 struct inode *wdir = workdir->d_inode;
217 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
218 struct inode *udir = upperdir->d_inode;
219 struct path upperpath;
220 struct dentry *upper;
221 struct dentry *opaquedir;
222 struct kstat stat;
223 int err;
224
cc6f67bc
MS		 225 if (WARN_ON(!workdir))
226 return ERR_PTR(-EROFS);
227
e9be9d5e
MS		 228 err = ovl_lock_rename_workdir(workdir, upperdir);
229 if (err)
230 goto out;
231
232 ovl_path_upper(dentry, &upperpath);
233 err = vfs_getattr(&upperpath, &stat);
234 if (err)
235 goto out_unlock;
236
237 err = -ESTALE;
238 if (!S_ISDIR(stat.mode))
239 goto out_unlock;
240 upper = upperpath.dentry;
241 if (upper->d_parent->d_inode != udir)
242 goto out_unlock;
243
244 opaquedir = ovl_lookup_temp(workdir, dentry);
245 err = PTR_ERR(opaquedir);
246 if (IS_ERR(opaquedir))
247 goto out_unlock;
248
249 err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
250 if (err)
251 goto out_dput;
252
253 err = ovl_copy_xattr(upper, opaquedir);
254 if (err)
255 goto out_cleanup;
256
257 err = ovl_set_opaque(opaquedir);
258 if (err)
259 goto out_cleanup;
260
5955102c 261 inode_lock(opaquedir->d_inode);
e9be9d5e 262 err = ovl_set_attr(opaquedir, &stat);
5955102c 263 inode_unlock(opaquedir->d_inode);
e9be9d5e
MS		 264 if (err)
265 goto out_cleanup;
266
267 err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
268 if (err)
269 goto out_cleanup;
270
271 ovl_cleanup_whiteouts(upper, list);
272 ovl_cleanup(wdir, upper);
273 unlock_rename(workdir, upperdir);
274
275 /* dentry's upper doesn't match now, get rid of it */
276 d_drop(dentry);
277
278 return opaquedir;
279
280out_cleanup:
281 ovl_cleanup(wdir, opaquedir);
282out_dput:
283 dput(opaquedir);
284out_unlock:
285 unlock_rename(workdir, upperdir);
286out:
287 return ERR_PTR(err);
288}
289
a105d685 290static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
e9be9d5e
MS		 291{
292 int err;
293 struct dentry *ret = NULL;
294 LIST_HEAD(list);
295
296 err = ovl_check_empty_dir(dentry, &list);
297 if (err)
298 ret = ERR_PTR(err);
a105d685
MS		 299 else {
300 /*
301 * If no upperdentry then skip clearing whiteouts.
302 *
303 * Can race with copy-up, since we don't hold the upperdir
304 * mutex. Doesn't matter, since copy-up can't create a
305 * non-empty directory from an empty one.
306 */
307 if (ovl_dentry_upper(dentry))
308 ret = ovl_clear_empty(dentry, &list);
309 }
e9be9d5e
MS		 310
311 ovl_cache_free(&list);
312
313 return ret;
314}
315
316static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
317 struct kstat *stat, const char *link,
318 struct dentry *hardlink)
319{
320 struct dentry *workdir = ovl_workdir(dentry);
321 struct inode *wdir = workdir->d_inode;
322 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
323 struct inode *udir = upperdir->d_inode;
324 struct dentry *upper;
325 struct dentry *newdentry;
326 int err;
327
cc6f67bc
MS		 328 if (WARN_ON(!workdir))
329 return -EROFS;
330
e9be9d5e
MS		 331 err = ovl_lock_rename_workdir(workdir, upperdir);
332 if (err)
333 goto out;
334
335 newdentry = ovl_lookup_temp(workdir, dentry);
336 err = PTR_ERR(newdentry);
337 if (IS_ERR(newdentry))
338 goto out_unlock;
339
340 upper = lookup_one_len(dentry->d_name.name, upperdir,
341 dentry->d_name.len);
342 err = PTR_ERR(upper);
343 if (IS_ERR(upper))
344 goto out_dput;
345
346 err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
347 if (err)
348 goto out_dput2;
349
350 if (S_ISDIR(stat->mode)) {
351 err = ovl_set_opaque(newdentry);
352 if (err)
353 goto out_cleanup;
354
355 err = ovl_do_rename(wdir, newdentry, udir, upper,
356 RENAME_EXCHANGE);
357 if (err)
358 goto out_cleanup;
359
360 ovl_cleanup(wdir, upper);
361 } else {
362 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
363 if (err)
364 goto out_cleanup;
365 }
366 ovl_dentry_version_inc(dentry->d_parent);
367 ovl_dentry_update(dentry, newdentry);
368 ovl_copyattr(newdentry->d_inode, inode);
369 d_instantiate(dentry, inode);
370 newdentry = NULL;
371out_dput2:
372 dput(upper);
373out_dput:
374 dput(newdentry);
375out_unlock:
376 unlock_rename(workdir, upperdir);
377out:
378 return err;
379
380out_cleanup:
381 ovl_cleanup(wdir, newdentry);
382 goto out_dput2;
383}
384
385static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
386 const char *link, struct dentry *hardlink)
387{
388 int err;
389 struct inode *inode;
390 struct kstat stat = {
391 .mode = mode,
392 .rdev = rdev,
393 };
394
395 err = -ENOMEM;
396 inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
397 if (!inode)
398 goto out;
399
400 err = ovl_copy_up(dentry->d_parent);
401 if (err)
402 goto out_iput;
403
404 if (!ovl_dentry_is_opaque(dentry)) {
405 err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
406 } else {
407 const struct cred *old_cred;
408 struct cred *override_cred;
409
410 err = -ENOMEM;
411 override_cred = prepare_creds();
412 if (!override_cred)
413 goto out_iput;
414
415 /*
416 * CAP_SYS_ADMIN for setting opaque xattr
417 * CAP_DAC_OVERRIDE for create in workdir, rename
418 * CAP_FOWNER for removing whiteout from sticky dir
419 */
420 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
421 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
422 cap_raise(override_cred->cap_effective, CAP_FOWNER);
423 old_cred = override_creds(override_cred);
424
425 err = ovl_create_over_whiteout(dentry, inode, &stat, link,
426 hardlink);
427
428 revert_creds(old_cred);
429 put_cred(override_cred);
430 }
431
432 if (!err)
433 inode = NULL;
434out_iput:
435 iput(inode);
436out:
437 return err;
438}
439
440static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
441 const char *link)
442{
443 int err;
444
445 err = ovl_want_write(dentry);
446 if (!err) {
447 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
448 ovl_drop_write(dentry);
449 }
450
451 return err;
452}
453
454static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
455 bool excl)
456{
457 return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
458}
459
460static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
461{
462 return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
463}
464
465static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
466 dev_t rdev)
467{
468 /* Don't allow creation of "whiteout" on overlay */
469 if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
470 return -EPERM;
471
472 return ovl_create_object(dentry, mode, rdev, NULL);
473}
474
475static int ovl_symlink(struct inode *dir, struct dentry *dentry,
476 const char *link)
477{
478 return ovl_create_object(dentry, S_IFLNK, 0, link);
479}
480
481static int ovl_link(struct dentry *old, struct inode *newdir,
482 struct dentry *new)
483{
484 int err;
485 struct dentry *upper;
486
487 err = ovl_want_write(old);
488 if (err)
489 goto out;
490
491 err = ovl_copy_up(old);
492 if (err)
493 goto out_drop_write;
494
495 upper = ovl_dentry_upper(old);
496 err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
497
498out_drop_write:
499 ovl_drop_write(old);
500out:
501 return err;
502}
503
a105d685 504static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
e9be9d5e
MS		 505{
506 struct dentry *workdir = ovl_workdir(dentry);
507 struct inode *wdir = workdir->d_inode;
508 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
509 struct inode *udir = upperdir->d_inode;
510 struct dentry *whiteout;
511 struct dentry *upper;
512 struct dentry *opaquedir = NULL;
513 int err;
514
cc6f67bc
MS		 515 if (WARN_ON(!workdir))
516 return -EROFS;
517
d377c5eb
MS		 518 if (is_dir) {
519 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
520 opaquedir = ovl_check_empty_and_clear(dentry);
521 err = PTR_ERR(opaquedir);
522 if (IS_ERR(opaquedir))
523 goto out;
524 } else {
525 LIST_HEAD(list);
526
527 /*
528 * When removing an empty opaque directory, then it
529 * makes no sense to replace it with an exact replica of
530 * itself. But emptiness still needs to be checked.
531 */
532 err = ovl_check_empty_dir(dentry, &list);
533 ovl_cache_free(&list);
534 if (err)
535 goto out;
536 }
e9be9d5e
MS		 537 }
538
539 err = ovl_lock_rename_workdir(workdir, upperdir);
540 if (err)
541 goto out_dput;
542
543 whiteout = ovl_whiteout(workdir, dentry);
544 err = PTR_ERR(whiteout);
545 if (IS_ERR(whiteout))
546 goto out_unlock;
547
a105d685
MS		 548 upper = ovl_dentry_upper(dentry);
549 if (!upper) {
e9be9d5e 550 upper = lookup_one_len(dentry->d_name.name, upperdir,
a105d685 551 dentry->d_name.len);
e9be9d5e
MS		 552 err = PTR_ERR(upper);
553 if (IS_ERR(upper))
554 goto kill_whiteout;
555
556 err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
557 dput(upper);
558 if (err)
559 goto kill_whiteout;
560 } else {
561 int flags = 0;
562
e9be9d5e
MS		 563 if (opaquedir)
564 upper = opaquedir;
565 err = -ESTALE;
566 if (upper->d_parent != upperdir)
567 goto kill_whiteout;
568
569 if (is_dir)
570 flags |= RENAME_EXCHANGE;
571
572 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
573 if (err)
574 goto kill_whiteout;
575
576 if (is_dir)
577 ovl_cleanup(wdir, upper);
578 }
579 ovl_dentry_version_inc(dentry->d_parent);
580out_d_drop:
581 d_drop(dentry);
582 dput(whiteout);
583out_unlock:
584 unlock_rename(workdir, upperdir);
585out_dput:
586 dput(opaquedir);
587out:
588 return err;
589
590kill_whiteout:
591 ovl_cleanup(wdir, whiteout);
592 goto out_d_drop;
593}
594
595static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
596{
597 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
598 struct inode *dir = upperdir->d_inode;
599 struct dentry *upper = ovl_dentry_upper(dentry);
600 int err;
601
5955102c 602 inode_lock_nested(dir, I_MUTEX_PARENT);
e9be9d5e
MS		 603 err = -ESTALE;
604 if (upper->d_parent == upperdir) {
605 /* Don't let d_delete() think it can reset d_inode */
606 dget(upper);
607 if (is_dir)
608 err = vfs_rmdir(dir, upper);
609 else
610 err = vfs_unlink(dir, upper, NULL);
611 dput(upper);
612 ovl_dentry_version_inc(dentry->d_parent);
613 }
614
615 /*
616 * Keeping this dentry hashed would mean having to release
617 * upperpath/lowerpath, which could only be done if we are the
618 * sole user of this dentry. Too tricky... Just unhash for
619 * now.
620 */
ce9113bb
RW		 621 if (!err)
622 d_drop(dentry);
5955102c 623 inode_unlock(dir);
e9be9d5e
MS		 624
625 return err;
626}
627
628static inline int ovl_check_sticky(struct dentry *dentry)
629{
630 struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
631 struct inode *inode = ovl_dentry_real(dentry)->d_inode;
632
633 if (check_sticky(dir, inode))
634 return -EPERM;
635
636 return 0;
637}
638
639static int ovl_do_remove(struct dentry *dentry, bool is_dir)
640{
641 enum ovl_path_type type;
642 int err;
643
644 err = ovl_check_sticky(dentry);
645 if (err)
646 goto out;
647
648 err = ovl_want_write(dentry);
649 if (err)
650 goto out;
651
652 err = ovl_copy_up(dentry->d_parent);
653 if (err)
654 goto out_drop_write;
655
656 type = ovl_path_type(dentry);
1afaba1e 657 if (OVL_TYPE_PURE_UPPER(type)) {
e9be9d5e
MS		 658 err = ovl_remove_upper(dentry, is_dir);
659 } else {
660 const struct cred *old_cred;
661 struct cred *override_cred;
662
663 err = -ENOMEM;
664 override_cred = prepare_creds();
665 if (!override_cred)
666 goto out_drop_write;
667
668 /*
669 * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
670 * CAP_DAC_OVERRIDE for create in workdir, rename
671 * CAP_FOWNER for removing whiteout from sticky dir
672 * CAP_FSETID for chmod of opaque dir
673 * CAP_CHOWN for chown of opaque dir
674 */
675 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
676 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
677 cap_raise(override_cred->cap_effective, CAP_FOWNER);
678 cap_raise(override_cred->cap_effective, CAP_FSETID);
679 cap_raise(override_cred->cap_effective, CAP_CHOWN);
680 old_cred = override_creds(override_cred);
681
a105d685 682 err = ovl_remove_and_whiteout(dentry, is_dir);
e9be9d5e
MS		 683
684 revert_creds(old_cred);
685 put_cred(override_cred);
686 }
687out_drop_write:
688 ovl_drop_write(dentry);
689out:
690 return err;
691}
692
693static int ovl_unlink(struct inode *dir, struct dentry *dentry)
694{
695 return ovl_do_remove(dentry, false);
696}
697
698static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
699{
700 return ovl_do_remove(dentry, true);
701}
702
703static int ovl_rename2(struct inode *olddir, struct dentry *old,
704 struct inode *newdir, struct dentry *new,
705 unsigned int flags)
706{
707 int err;
708 enum ovl_path_type old_type;
709 enum ovl_path_type new_type;
710 struct dentry *old_upperdir;
711 struct dentry *new_upperdir;
712 struct dentry *olddentry;
713 struct dentry *newdentry;
714 struct dentry *trap;
715 bool old_opaque;
716 bool new_opaque;
717 bool new_create = false;
718 bool cleanup_whiteout = false;
719 bool overwrite = !(flags & RENAME_EXCHANGE);
e36cb0b8 720 bool is_dir = d_is_dir(old);
e9be9d5e
MS		 721 bool new_is_dir = false;
722 struct dentry *opaquedir = NULL;
723 const struct cred *old_cred = NULL;
724 struct cred *override_cred = NULL;
725
726 err = -EINVAL;
727 if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
728 goto out;
729
730 flags &= ~RENAME_NOREPLACE;
731
732 err = ovl_check_sticky(old);
733 if (err)
734 goto out;
735
736 /* Don't copy up directory trees */
737 old_type = ovl_path_type(old);
738 err = -EXDEV;
1afaba1e 739 if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
e9be9d5e
MS		 740 goto out;
741
742 if (new->d_inode) {
743 err = ovl_check_sticky(new);
744 if (err)
745 goto out;
746
e36cb0b8 747 if (d_is_dir(new))
e9be9d5e
MS		 748 new_is_dir = true;
749
750 new_type = ovl_path_type(new);
751 err = -EXDEV;
1afaba1e 752 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
e9be9d5e
MS		 753 goto out;
754
755 err = 0;
1afaba1e 756 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
e9be9d5e
MS		 757 if (ovl_dentry_lower(old)->d_inode ==
758 ovl_dentry_lower(new)->d_inode)
759 goto out;
760 }
1afaba1e 761 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
e9be9d5e
MS		 762 if (ovl_dentry_upper(old)->d_inode ==
763 ovl_dentry_upper(new)->d_inode)
764 goto out;
765 }
766 } else {
767 if (ovl_dentry_is_opaque(new))
1afaba1e 768 new_type = __OVL_PATH_UPPER;
e9be9d5e 769 else
1afaba1e 770 new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
e9be9d5e
MS		 771 }
772
773 err = ovl_want_write(old);
774 if (err)
775 goto out;
776
777 err = ovl_copy_up(old);
778 if (err)
779 goto out_drop_write;
780
781 err = ovl_copy_up(new->d_parent);
782 if (err)
783 goto out_drop_write;
784 if (!overwrite) {
785 err = ovl_copy_up(new);
786 if (err)
787 goto out_drop_write;
788 }
789
1afaba1e
MS		 790 old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
791 new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
e9be9d5e
MS		 792
793 if (old_opaque || new_opaque) {
794 err = -ENOMEM;
795 override_cred = prepare_creds();
796 if (!override_cred)
797 goto out_drop_write;
798
799 /*
800 * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
801 * CAP_DAC_OVERRIDE for create in workdir
802 * CAP_FOWNER for removing whiteout from sticky dir
803 * CAP_FSETID for chmod of opaque dir
804 * CAP_CHOWN for chown of opaque dir
805 */
806 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
807 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
808 cap_raise(override_cred->cap_effective, CAP_FOWNER);
809 cap_raise(override_cred->cap_effective, CAP_FSETID);
810 cap_raise(override_cred->cap_effective, CAP_CHOWN);
811 old_cred = override_creds(override_cred);
812 }
813
1afaba1e 814 if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
a105d685 815 opaquedir = ovl_check_empty_and_clear(new);
e9be9d5e
MS		 816 err = PTR_ERR(opaquedir);
817 if (IS_ERR(opaquedir)) {
818 opaquedir = NULL;
819 goto out_revert_creds;
820 }
821 }
822
823 if (overwrite) {
824 if (old_opaque) {
825 if (new->d_inode || !new_opaque) {
826 /* Whiteout source */
827 flags |= RENAME_WHITEOUT;
828 } else {
829 /* Switch whiteouts */
830 flags |= RENAME_EXCHANGE;
831 }
832 } else if (is_dir && !new->d_inode && new_opaque) {
833 flags |= RENAME_EXCHANGE;
834 cleanup_whiteout = true;
835 }
836 }
837
838 old_upperdir = ovl_dentry_upper(old->d_parent);
839 new_upperdir = ovl_dentry_upper(new->d_parent);
840
841 trap = lock_rename(new_upperdir, old_upperdir);
842
843 olddentry = ovl_dentry_upper(old);
844 newdentry = ovl_dentry_upper(new);
845 if (newdentry) {
846 if (opaquedir) {
847 newdentry = opaquedir;
848 opaquedir = NULL;
849 } else {
850 dget(newdentry);
851 }
852 } else {
853 new_create = true;
854 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
855 new->d_name.len);
856 err = PTR_ERR(newdentry);
857 if (IS_ERR(newdentry))
858 goto out_unlock;
859 }
860
861 err = -ESTALE;
862 if (olddentry->d_parent != old_upperdir)
863 goto out_dput;
864 if (newdentry->d_parent != new_upperdir)
865 goto out_dput;
866 if (olddentry == trap)
867 goto out_dput;
868 if (newdentry == trap)
869 goto out_dput;
870
871 if (is_dir && !old_opaque && new_opaque) {
872 err = ovl_set_opaque(olddentry);
873 if (err)
874 goto out_dput;
875 }
876 if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
877 err = ovl_set_opaque(newdentry);
878 if (err)
879 goto out_dput;
880 }
881
882 if (old_opaque || new_opaque) {
883 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
884 new_upperdir->d_inode, newdentry,
885 flags);
886 } else {
887 /* No debug for the plain case */
888 BUG_ON(flags & ~RENAME_EXCHANGE);
889 err = vfs_rename(old_upperdir->d_inode, olddentry,
890 new_upperdir->d_inode, newdentry,
891 NULL, flags);
892 }
893
894 if (err) {
895 if (is_dir && !old_opaque && new_opaque)
896 ovl_remove_opaque(olddentry);
897 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
898 ovl_remove_opaque(newdentry);
899 goto out_dput;
900 }
901
902 if (is_dir && old_opaque && !new_opaque)
903 ovl_remove_opaque(olddentry);
904 if (!overwrite && new_is_dir && !old_opaque && new_opaque)
905 ovl_remove_opaque(newdentry);
906
45d11738
KK		 907 /*
908 * Old dentry now lives in different location. Dentries in
909 * lowerstack are stale. We cannot drop them here because
910 * access to them is lockless. This could be only pure upper
911 * or opaque directory - numlower is zero. Or upper non-dir
912 * entry - its pureness is tracked by flag opaque.
913 */
e9be9d5e
MS		 914 if (old_opaque != new_opaque) {
915 ovl_dentry_set_opaque(old, new_opaque);
916 if (!overwrite)
917 ovl_dentry_set_opaque(new, old_opaque);
918 }
919
920 if (cleanup_whiteout)
921 ovl_cleanup(old_upperdir->d_inode, newdentry);
922
923 ovl_dentry_version_inc(old->d_parent);
924 ovl_dentry_version_inc(new->d_parent);
925
926out_dput:
927 dput(newdentry);
928out_unlock:
929 unlock_rename(new_upperdir, old_upperdir);
930out_revert_creds:
931 if (old_opaque || new_opaque) {
932 revert_creds(old_cred);
933 put_cred(override_cred);
934 }
935out_drop_write:
936 ovl_drop_write(old);
937out:
938 dput(opaquedir);
939 return err;
940}
941
942const struct inode_operations ovl_dir_inode_operations = {
943 .lookup = ovl_lookup,
944 .mkdir = ovl_mkdir,
945 .symlink = ovl_symlink,
946 .unlink = ovl_unlink,
947 .rmdir = ovl_rmdir,
948 .rename2 = ovl_rename2,
949 .link = ovl_link,
950 .setattr = ovl_setattr,
951 .create = ovl_create,
952 .mknod = ovl_mknod,
953 .permission = ovl_permission,
954 .getattr = ovl_dir_getattr,
955 .setxattr = ovl_setxattr,
956 .getxattr = ovl_getxattr,
957 .listxattr = ovl_listxattr,
958 .removexattr = ovl_removexattr,
959};
Linux 6.x block layer and io_uring tree(s)