xref: /openbmc/linux/fs/overlayfs/dir.c (revision f0702555)
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 
17 void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
18 {
19 	int err;
20 
21 	dget(wdentry);
22 	if (d_is_dir(wdentry))
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 
34 struct 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 */
52 static 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 
72 int 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 
119 static int ovl_set_opaque(struct dentry *upperdentry)
120 {
121 	return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
122 }
123 
124 static void ovl_remove_opaque(struct dentry *upperdentry)
125 {
126 	int err;
127 
128 	err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
129 	if (err) {
130 		pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
131 			upperdentry->d_name.name, err);
132 	}
133 }
134 
135 static 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 	 */
155 	if (OVL_TYPE_MERGE(type))
156 		stat->nlink = 1;
157 
158 	return 0;
159 }
160 
161 static 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 
170 	inode_lock_nested(udir, I_MUTEX_PARENT);
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;
185 out_dput:
186 	dput(newdentry);
187 out_unlock:
188 	inode_unlock(udir);
189 	return err;
190 }
191 
192 static 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 
205 err_unlock:
206 	unlock_rename(workdir, upperdir);
207 err:
208 	pr_err("overlayfs: failed to lock workdir+upperdir\n");
209 	return -EIO;
210 }
211 
212 static 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 
225 	if (WARN_ON(!workdir))
226 		return ERR_PTR(-EROFS);
227 
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 
261 	inode_lock(opaquedir->d_inode);
262 	err = ovl_set_attr(opaquedir, &stat);
263 	inode_unlock(opaquedir->d_inode);
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 
280 out_cleanup:
281 	ovl_cleanup(wdir, opaquedir);
282 out_dput:
283 	dput(opaquedir);
284 out_unlock:
285 	unlock_rename(workdir, upperdir);
286 out:
287 	return ERR_PTR(err);
288 }
289 
290 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
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);
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 	}
310 
311 	ovl_cache_free(&list);
312 
313 	return ret;
314 }
315 
316 static 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 
328 	if (WARN_ON(!workdir))
329 		return -EROFS;
330 
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;
371 out_dput2:
372 	dput(upper);
373 out_dput:
374 	dput(newdentry);
375 out_unlock:
376 	unlock_rename(workdir, upperdir);
377 out:
378 	return err;
379 
380 out_cleanup:
381 	ovl_cleanup(wdir, newdentry);
382 	goto out_dput2;
383 }
384 
385 static 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 
409 		old_cred = ovl_override_creds(dentry->d_sb);
410 
411 		err = ovl_create_over_whiteout(dentry, inode, &stat, link,
412 					       hardlink);
413 
414 		revert_creds(old_cred);
415 	}
416 
417 	if (!err)
418 		inode = NULL;
419 out_iput:
420 	iput(inode);
421 out:
422 	return err;
423 }
424 
425 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
426 			     const char *link)
427 {
428 	int err;
429 
430 	err = ovl_want_write(dentry);
431 	if (!err) {
432 		err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
433 		ovl_drop_write(dentry);
434 	}
435 
436 	return err;
437 }
438 
439 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
440 		      bool excl)
441 {
442 	return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
443 }
444 
445 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
446 {
447 	return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
448 }
449 
450 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
451 		     dev_t rdev)
452 {
453 	/* Don't allow creation of "whiteout" on overlay */
454 	if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
455 		return -EPERM;
456 
457 	return ovl_create_object(dentry, mode, rdev, NULL);
458 }
459 
460 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
461 		       const char *link)
462 {
463 	return ovl_create_object(dentry, S_IFLNK, 0, link);
464 }
465 
466 static int ovl_link(struct dentry *old, struct inode *newdir,
467 		    struct dentry *new)
468 {
469 	int err;
470 	struct dentry *upper;
471 
472 	err = ovl_want_write(old);
473 	if (err)
474 		goto out;
475 
476 	err = ovl_copy_up(old);
477 	if (err)
478 		goto out_drop_write;
479 
480 	upper = ovl_dentry_upper(old);
481 	err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
482 
483 out_drop_write:
484 	ovl_drop_write(old);
485 out:
486 	return err;
487 }
488 
489 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
490 {
491 	struct dentry *workdir = ovl_workdir(dentry);
492 	struct inode *wdir = workdir->d_inode;
493 	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
494 	struct inode *udir = upperdir->d_inode;
495 	struct dentry *whiteout;
496 	struct dentry *upper;
497 	struct dentry *opaquedir = NULL;
498 	int err;
499 
500 	if (WARN_ON(!workdir))
501 		return -EROFS;
502 
503 	if (is_dir) {
504 		if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
505 			opaquedir = ovl_check_empty_and_clear(dentry);
506 			err = PTR_ERR(opaquedir);
507 			if (IS_ERR(opaquedir))
508 				goto out;
509 		} else {
510 			LIST_HEAD(list);
511 
512 			/*
513 			 * When removing an empty opaque directory, then it
514 			 * makes no sense to replace it with an exact replica of
515 			 * itself.  But emptiness still needs to be checked.
516 			 */
517 			err = ovl_check_empty_dir(dentry, &list);
518 			ovl_cache_free(&list);
519 			if (err)
520 				goto out;
521 		}
522 	}
523 
524 	err = ovl_lock_rename_workdir(workdir, upperdir);
525 	if (err)
526 		goto out_dput;
527 
528 	whiteout = ovl_whiteout(workdir, dentry);
529 	err = PTR_ERR(whiteout);
530 	if (IS_ERR(whiteout))
531 		goto out_unlock;
532 
533 	upper = ovl_dentry_upper(dentry);
534 	if (!upper) {
535 		upper = lookup_one_len(dentry->d_name.name, upperdir,
536 				       dentry->d_name.len);
537 		err = PTR_ERR(upper);
538 		if (IS_ERR(upper))
539 			goto kill_whiteout;
540 
541 		err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
542 		dput(upper);
543 		if (err)
544 			goto kill_whiteout;
545 	} else {
546 		int flags = 0;
547 
548 		if (opaquedir)
549 			upper = opaquedir;
550 		err = -ESTALE;
551 		if (upper->d_parent != upperdir)
552 			goto kill_whiteout;
553 
554 		if (is_dir)
555 			flags |= RENAME_EXCHANGE;
556 
557 		err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
558 		if (err)
559 			goto kill_whiteout;
560 
561 		if (is_dir)
562 			ovl_cleanup(wdir, upper);
563 	}
564 	ovl_dentry_version_inc(dentry->d_parent);
565 out_d_drop:
566 	d_drop(dentry);
567 	dput(whiteout);
568 out_unlock:
569 	unlock_rename(workdir, upperdir);
570 out_dput:
571 	dput(opaquedir);
572 out:
573 	return err;
574 
575 kill_whiteout:
576 	ovl_cleanup(wdir, whiteout);
577 	goto out_d_drop;
578 }
579 
580 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
581 {
582 	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
583 	struct inode *dir = upperdir->d_inode;
584 	struct dentry *upper;
585 	int err;
586 
587 	inode_lock_nested(dir, I_MUTEX_PARENT);
588 	upper = lookup_one_len(dentry->d_name.name, upperdir,
589 			       dentry->d_name.len);
590 	err = PTR_ERR(upper);
591 	if (IS_ERR(upper))
592 		goto out_unlock;
593 
594 	err = -ESTALE;
595 	if (upper == ovl_dentry_upper(dentry)) {
596 		if (is_dir)
597 			err = vfs_rmdir(dir, upper);
598 		else
599 			err = vfs_unlink(dir, upper, NULL);
600 		ovl_dentry_version_inc(dentry->d_parent);
601 	}
602 	dput(upper);
603 
604 	/*
605 	 * Keeping this dentry hashed would mean having to release
606 	 * upperpath/lowerpath, which could only be done if we are the
607 	 * sole user of this dentry.  Too tricky...  Just unhash for
608 	 * now.
609 	 */
610 	if (!err)
611 		d_drop(dentry);
612 out_unlock:
613 	inode_unlock(dir);
614 
615 	return err;
616 }
617 
618 static inline int ovl_check_sticky(struct dentry *dentry)
619 {
620 	struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
621 	struct inode *inode = ovl_dentry_real(dentry)->d_inode;
622 
623 	if (check_sticky(dir, inode))
624 		return -EPERM;
625 
626 	return 0;
627 }
628 
629 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
630 {
631 	enum ovl_path_type type;
632 	int err;
633 
634 	err = ovl_check_sticky(dentry);
635 	if (err)
636 		goto out;
637 
638 	err = ovl_want_write(dentry);
639 	if (err)
640 		goto out;
641 
642 	err = ovl_copy_up(dentry->d_parent);
643 	if (err)
644 		goto out_drop_write;
645 
646 	type = ovl_path_type(dentry);
647 	if (OVL_TYPE_PURE_UPPER(type)) {
648 		err = ovl_remove_upper(dentry, is_dir);
649 	} else {
650 		const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
651 
652 		err = ovl_remove_and_whiteout(dentry, is_dir);
653 
654 		revert_creds(old_cred);
655 	}
656 out_drop_write:
657 	ovl_drop_write(dentry);
658 out:
659 	return err;
660 }
661 
662 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
663 {
664 	return ovl_do_remove(dentry, false);
665 }
666 
667 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
668 {
669 	return ovl_do_remove(dentry, true);
670 }
671 
672 static int ovl_rename2(struct inode *olddir, struct dentry *old,
673 		       struct inode *newdir, struct dentry *new,
674 		       unsigned int flags)
675 {
676 	int err;
677 	enum ovl_path_type old_type;
678 	enum ovl_path_type new_type;
679 	struct dentry *old_upperdir;
680 	struct dentry *new_upperdir;
681 	struct dentry *olddentry;
682 	struct dentry *newdentry;
683 	struct dentry *trap;
684 	bool old_opaque;
685 	bool new_opaque;
686 	bool cleanup_whiteout = false;
687 	bool overwrite = !(flags & RENAME_EXCHANGE);
688 	bool is_dir = d_is_dir(old);
689 	bool new_is_dir = false;
690 	struct dentry *opaquedir = NULL;
691 	const struct cred *old_cred = NULL;
692 
693 	err = -EINVAL;
694 	if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
695 		goto out;
696 
697 	flags &= ~RENAME_NOREPLACE;
698 
699 	err = ovl_check_sticky(old);
700 	if (err)
701 		goto out;
702 
703 	/* Don't copy up directory trees */
704 	old_type = ovl_path_type(old);
705 	err = -EXDEV;
706 	if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
707 		goto out;
708 
709 	if (new->d_inode) {
710 		err = ovl_check_sticky(new);
711 		if (err)
712 			goto out;
713 
714 		if (d_is_dir(new))
715 			new_is_dir = true;
716 
717 		new_type = ovl_path_type(new);
718 		err = -EXDEV;
719 		if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
720 			goto out;
721 
722 		err = 0;
723 		if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
724 			if (ovl_dentry_lower(old)->d_inode ==
725 			    ovl_dentry_lower(new)->d_inode)
726 				goto out;
727 		}
728 		if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
729 			if (ovl_dentry_upper(old)->d_inode ==
730 			    ovl_dentry_upper(new)->d_inode)
731 				goto out;
732 		}
733 	} else {
734 		if (ovl_dentry_is_opaque(new))
735 			new_type = __OVL_PATH_UPPER;
736 		else
737 			new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
738 	}
739 
740 	err = ovl_want_write(old);
741 	if (err)
742 		goto out;
743 
744 	err = ovl_copy_up(old);
745 	if (err)
746 		goto out_drop_write;
747 
748 	err = ovl_copy_up(new->d_parent);
749 	if (err)
750 		goto out_drop_write;
751 	if (!overwrite) {
752 		err = ovl_copy_up(new);
753 		if (err)
754 			goto out_drop_write;
755 	}
756 
757 	old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
758 	new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
759 
760 	if (old_opaque || new_opaque)
761 		old_cred = ovl_override_creds(old->d_sb);
762 
763 	if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
764 		opaquedir = ovl_check_empty_and_clear(new);
765 		err = PTR_ERR(opaquedir);
766 		if (IS_ERR(opaquedir)) {
767 			opaquedir = NULL;
768 			goto out_revert_creds;
769 		}
770 	}
771 
772 	if (overwrite) {
773 		if (old_opaque) {
774 			if (new->d_inode || !new_opaque) {
775 				/* Whiteout source */
776 				flags |= RENAME_WHITEOUT;
777 			} else {
778 				/* Switch whiteouts */
779 				flags |= RENAME_EXCHANGE;
780 			}
781 		} else if (is_dir && !new->d_inode && new_opaque) {
782 			flags |= RENAME_EXCHANGE;
783 			cleanup_whiteout = true;
784 		}
785 	}
786 
787 	old_upperdir = ovl_dentry_upper(old->d_parent);
788 	new_upperdir = ovl_dentry_upper(new->d_parent);
789 
790 	trap = lock_rename(new_upperdir, old_upperdir);
791 
792 
793 	olddentry = lookup_one_len(old->d_name.name, old_upperdir,
794 				   old->d_name.len);
795 	err = PTR_ERR(olddentry);
796 	if (IS_ERR(olddentry))
797 		goto out_unlock;
798 
799 	err = -ESTALE;
800 	if (olddentry != ovl_dentry_upper(old))
801 		goto out_dput_old;
802 
803 	newdentry = lookup_one_len(new->d_name.name, new_upperdir,
804 				   new->d_name.len);
805 	err = PTR_ERR(newdentry);
806 	if (IS_ERR(newdentry))
807 		goto out_dput_old;
808 
809 	err = -ESTALE;
810 	if (ovl_dentry_upper(new)) {
811 		if (opaquedir) {
812 			if (newdentry != opaquedir)
813 				goto out_dput;
814 		} else {
815 			if (newdentry != ovl_dentry_upper(new))
816 				goto out_dput;
817 		}
818 	} else {
819 		if (!d_is_negative(newdentry) &&
820 		    (!new_opaque || !ovl_is_whiteout(newdentry)))
821 			goto out_dput;
822 	}
823 
824 	if (olddentry == trap)
825 		goto out_dput;
826 	if (newdentry == trap)
827 		goto out_dput;
828 
829 	if (is_dir && !old_opaque && new_opaque) {
830 		err = ovl_set_opaque(olddentry);
831 		if (err)
832 			goto out_dput;
833 	}
834 	if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
835 		err = ovl_set_opaque(newdentry);
836 		if (err)
837 			goto out_dput;
838 	}
839 
840 	if (old_opaque || new_opaque) {
841 		err = ovl_do_rename(old_upperdir->d_inode, olddentry,
842 				    new_upperdir->d_inode, newdentry,
843 				    flags);
844 	} else {
845 		/* No debug for the plain case */
846 		BUG_ON(flags & ~RENAME_EXCHANGE);
847 		err = vfs_rename(old_upperdir->d_inode, olddentry,
848 				 new_upperdir->d_inode, newdentry,
849 				 NULL, flags);
850 	}
851 
852 	if (err) {
853 		if (is_dir && !old_opaque && new_opaque)
854 			ovl_remove_opaque(olddentry);
855 		if (!overwrite && new_is_dir && old_opaque && !new_opaque)
856 			ovl_remove_opaque(newdentry);
857 		goto out_dput;
858 	}
859 
860 	if (is_dir && old_opaque && !new_opaque)
861 		ovl_remove_opaque(olddentry);
862 	if (!overwrite && new_is_dir && !old_opaque && new_opaque)
863 		ovl_remove_opaque(newdentry);
864 
865 	/*
866 	 * Old dentry now lives in different location. Dentries in
867 	 * lowerstack are stale. We cannot drop them here because
868 	 * access to them is lockless. This could be only pure upper
869 	 * or opaque directory - numlower is zero. Or upper non-dir
870 	 * entry - its pureness is tracked by flag opaque.
871 	 */
872 	if (old_opaque != new_opaque) {
873 		ovl_dentry_set_opaque(old, new_opaque);
874 		if (!overwrite)
875 			ovl_dentry_set_opaque(new, old_opaque);
876 	}
877 
878 	if (cleanup_whiteout)
879 		ovl_cleanup(old_upperdir->d_inode, newdentry);
880 
881 	ovl_dentry_version_inc(old->d_parent);
882 	ovl_dentry_version_inc(new->d_parent);
883 
884 out_dput:
885 	dput(newdentry);
886 out_dput_old:
887 	dput(olddentry);
888 out_unlock:
889 	unlock_rename(new_upperdir, old_upperdir);
890 out_revert_creds:
891 	if (old_opaque || new_opaque)
892 		revert_creds(old_cred);
893 out_drop_write:
894 	ovl_drop_write(old);
895 out:
896 	dput(opaquedir);
897 	return err;
898 }
899 
900 const struct inode_operations ovl_dir_inode_operations = {
901 	.lookup		= ovl_lookup,
902 	.mkdir		= ovl_mkdir,
903 	.symlink	= ovl_symlink,
904 	.unlink		= ovl_unlink,
905 	.rmdir		= ovl_rmdir,
906 	.rename2	= ovl_rename2,
907 	.link		= ovl_link,
908 	.setattr	= ovl_setattr,
909 	.create		= ovl_create,
910 	.mknod		= ovl_mknod,
911 	.permission	= ovl_permission,
912 	.getattr	= ovl_dir_getattr,
913 	.setxattr	= ovl_setxattr,
914 	.getxattr	= ovl_getxattr,
915 	.listxattr	= ovl_listxattr,
916 	.removexattr	= ovl_removexattr,
917 };
918