3 * Copyright (C) 2011 Novell Inc.
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.
11 #include <linux/namei.h>
12 #include <linux/xattr.h>
13 #include <linux/security.h>
14 #include <linux/cred.h>
15 #include "overlayfs.h"
17 void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
22 if (d_is_dir(wdentry))
23 err = ovl_do_rmdir(wdir, wdentry);
25 err = ovl_do_unlink(wdir, wdentry);
29 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
34 struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
39 snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);
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);
51 /* caller holds i_mutex on workdir */
52 static struct dentry *ovl_whiteout(struct dentry *workdir,
53 struct dentry *dentry)
56 struct dentry *whiteout;
57 struct inode *wdir = workdir->d_inode;
59 whiteout = ovl_lookup_temp(workdir, dentry);
63 err = ovl_do_whiteout(wdir, whiteout);
66 whiteout = ERR_PTR(err);
72 int ovl_create_real(struct inode *dir, struct dentry *newdentry,
73 struct kstat *stat, const char *link,
74 struct dentry *hardlink, bool debug)
78 if (newdentry->d_inode)
82 err = ovl_do_link(hardlink, dir, newdentry, debug);
84 switch (stat->mode & S_IFMT) {
86 err = ovl_do_create(dir, newdentry, stat->mode, debug);
90 err = ovl_do_mkdir(dir, newdentry, stat->mode, debug);
97 err = ovl_do_mknod(dir, newdentry,
98 stat->mode, stat->rdev, debug);
102 err = ovl_do_symlink(dir, newdentry, link, debug);
109 if (!err && WARN_ON(!newdentry->d_inode)) {
111 * Not quite sure if non-instantiated dentry is legal or not.
112 * VFS doesn't seem to care so check and warn here.
119 static int ovl_set_opaque(struct dentry *upperdentry)
121 return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
124 static void ovl_remove_opaque(struct dentry *upperdentry)
128 err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
130 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
131 upperdentry->d_name.name, err);
135 static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
139 enum ovl_path_type type;
140 struct path realpath;
142 type = ovl_path_real(dentry, &realpath);
143 err = vfs_getattr(&realpath, stat);
147 stat->dev = dentry->d_sb->s_dev;
148 stat->ino = dentry->d_inode->i_ino;
151 * It's probably not worth it to count subdirs to get the
152 * correct link count. nlink=1 seems to pacify 'find' and
155 if (OVL_TYPE_MERGE(type))
161 /* Common operations required to be done after creation of file on upper */
162 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
163 struct dentry *newdentry)
165 ovl_dentry_version_inc(dentry->d_parent);
166 ovl_dentry_update(dentry, newdentry);
167 ovl_copyattr(newdentry->d_inode, inode);
168 d_instantiate(dentry, inode);
171 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
172 struct kstat *stat, const char *link,
173 struct dentry *hardlink)
175 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
176 struct inode *udir = upperdir->d_inode;
177 struct dentry *newdentry;
180 inode_lock_nested(udir, I_MUTEX_PARENT);
181 newdentry = lookup_one_len(dentry->d_name.name, upperdir,
183 err = PTR_ERR(newdentry);
184 if (IS_ERR(newdentry))
186 err = ovl_create_real(udir, newdentry, stat, link, hardlink, false);
190 ovl_instantiate(dentry, inode, newdentry);
199 static int ovl_lock_rename_workdir(struct dentry *workdir,
200 struct dentry *upperdir)
202 /* Workdir should not be the same as upperdir */
203 if (workdir == upperdir)
206 /* Workdir should not be subdir of upperdir and vice versa */
207 if (lock_rename(workdir, upperdir) != NULL)
213 unlock_rename(workdir, upperdir);
215 pr_err("overlayfs: failed to lock workdir+upperdir\n");
219 static struct dentry *ovl_clear_empty(struct dentry *dentry,
220 struct list_head *list)
222 struct dentry *workdir = ovl_workdir(dentry);
223 struct inode *wdir = workdir->d_inode;
224 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
225 struct inode *udir = upperdir->d_inode;
226 struct path upperpath;
227 struct dentry *upper;
228 struct dentry *opaquedir;
232 if (WARN_ON(!workdir))
233 return ERR_PTR(-EROFS);
235 err = ovl_lock_rename_workdir(workdir, upperdir);
239 ovl_path_upper(dentry, &upperpath);
240 err = vfs_getattr(&upperpath, &stat);
245 if (!S_ISDIR(stat.mode))
247 upper = upperpath.dentry;
248 if (upper->d_parent->d_inode != udir)
251 opaquedir = ovl_lookup_temp(workdir, dentry);
252 err = PTR_ERR(opaquedir);
253 if (IS_ERR(opaquedir))
256 err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
260 err = ovl_copy_xattr(upper, opaquedir);
264 err = ovl_set_opaque(opaquedir);
268 inode_lock(opaquedir->d_inode);
269 err = ovl_set_attr(opaquedir, &stat);
270 inode_unlock(opaquedir->d_inode);
274 err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
278 ovl_cleanup_whiteouts(upper, list);
279 ovl_cleanup(wdir, upper);
280 unlock_rename(workdir, upperdir);
282 /* dentry's upper doesn't match now, get rid of it */
288 ovl_cleanup(wdir, opaquedir);
292 unlock_rename(workdir, upperdir);
297 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
300 struct dentry *ret = NULL;
303 err = ovl_check_empty_dir(dentry, &list);
308 * If no upperdentry then skip clearing whiteouts.
310 * Can race with copy-up, since we don't hold the upperdir
311 * mutex. Doesn't matter, since copy-up can't create a
312 * non-empty directory from an empty one.
314 if (ovl_dentry_upper(dentry))
315 ret = ovl_clear_empty(dentry, &list);
318 ovl_cache_free(&list);
323 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
324 struct kstat *stat, const char *link,
325 struct dentry *hardlink)
327 struct dentry *workdir = ovl_workdir(dentry);
328 struct inode *wdir = workdir->d_inode;
329 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
330 struct inode *udir = upperdir->d_inode;
331 struct dentry *upper;
332 struct dentry *newdentry;
335 if (WARN_ON(!workdir))
338 err = ovl_lock_rename_workdir(workdir, upperdir);
342 newdentry = ovl_lookup_temp(workdir, dentry);
343 err = PTR_ERR(newdentry);
344 if (IS_ERR(newdentry))
347 upper = lookup_one_len(dentry->d_name.name, upperdir,
349 err = PTR_ERR(upper);
353 err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
357 if (S_ISDIR(stat->mode)) {
358 err = ovl_set_opaque(newdentry);
362 err = ovl_do_rename(wdir, newdentry, udir, upper,
367 ovl_cleanup(wdir, upper);
369 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
373 ovl_instantiate(dentry, inode, newdentry);
380 unlock_rename(workdir, upperdir);
385 ovl_cleanup(wdir, newdentry);
389 static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
390 const char *link, struct dentry *hardlink)
394 struct kstat stat = {
400 inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
404 err = ovl_copy_up(dentry->d_parent);
408 if (!ovl_dentry_is_opaque(dentry)) {
409 err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
411 const struct cred *old_cred;
412 struct cred *override_cred;
414 old_cred = ovl_override_creds(dentry->d_sb);
417 override_cred = prepare_creds();
419 override_cred->fsuid = old_cred->fsuid;
420 override_cred->fsgid = old_cred->fsgid;
421 put_cred(override_creds(override_cred));
422 put_cred(override_cred);
424 err = ovl_create_over_whiteout(dentry, inode, &stat,
427 revert_creds(old_cred);
438 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
443 err = ovl_want_write(dentry);
445 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
446 ovl_drop_write(dentry);
452 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
455 return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
458 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
460 return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
463 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
466 /* Don't allow creation of "whiteout" on overlay */
467 if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
470 return ovl_create_object(dentry, mode, rdev, NULL);
473 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
476 return ovl_create_object(dentry, S_IFLNK, 0, link);
479 static int ovl_link(struct dentry *old, struct inode *newdir,
483 struct dentry *upper;
485 err = ovl_want_write(old);
489 err = ovl_copy_up(old);
493 upper = ovl_dentry_upper(old);
494 err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
502 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
504 struct dentry *workdir = ovl_workdir(dentry);
505 struct inode *wdir = workdir->d_inode;
506 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
507 struct inode *udir = upperdir->d_inode;
508 struct dentry *whiteout;
509 struct dentry *upper;
510 struct dentry *opaquedir = NULL;
514 if (WARN_ON(!workdir))
518 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
519 opaquedir = ovl_check_empty_and_clear(dentry);
520 err = PTR_ERR(opaquedir);
521 if (IS_ERR(opaquedir))
527 * When removing an empty opaque directory, then it
528 * makes no sense to replace it with an exact replica of
529 * itself. But emptiness still needs to be checked.
531 err = ovl_check_empty_dir(dentry, &list);
532 ovl_cache_free(&list);
538 err = ovl_lock_rename_workdir(workdir, upperdir);
542 upper = lookup_one_len(dentry->d_name.name, upperdir,
544 err = PTR_ERR(upper);
549 if ((opaquedir && upper != opaquedir) ||
550 (!opaquedir && ovl_dentry_upper(dentry) &&
551 upper != ovl_dentry_upper(dentry))) {
555 whiteout = ovl_whiteout(workdir, dentry);
556 err = PTR_ERR(whiteout);
557 if (IS_ERR(whiteout))
561 flags = RENAME_EXCHANGE;
563 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
567 ovl_cleanup(wdir, upper);
569 ovl_dentry_version_inc(dentry->d_parent);
576 unlock_rename(workdir, upperdir);
583 ovl_cleanup(wdir, whiteout);
587 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
589 struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
590 struct inode *dir = upperdir->d_inode;
591 struct dentry *upper;
594 inode_lock_nested(dir, I_MUTEX_PARENT);
595 upper = lookup_one_len(dentry->d_name.name, upperdir,
597 err = PTR_ERR(upper);
602 if (upper == ovl_dentry_upper(dentry)) {
604 err = vfs_rmdir(dir, upper);
606 err = vfs_unlink(dir, upper, NULL);
607 ovl_dentry_version_inc(dentry->d_parent);
612 * Keeping this dentry hashed would mean having to release
613 * upperpath/lowerpath, which could only be done if we are the
614 * sole user of this dentry. Too tricky... Just unhash for
625 static inline int ovl_check_sticky(struct dentry *dentry)
627 struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
628 struct inode *inode = ovl_dentry_real(dentry)->d_inode;
630 if (check_sticky(dir, inode))
636 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
638 enum ovl_path_type type;
641 err = ovl_check_sticky(dentry);
645 err = ovl_want_write(dentry);
649 err = ovl_copy_up(dentry->d_parent);
653 type = ovl_path_type(dentry);
654 if (OVL_TYPE_PURE_UPPER(type)) {
655 err = ovl_remove_upper(dentry, is_dir);
657 const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
659 err = ovl_remove_and_whiteout(dentry, is_dir);
661 revert_creds(old_cred);
664 ovl_drop_write(dentry);
669 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
671 return ovl_do_remove(dentry, false);
674 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
676 return ovl_do_remove(dentry, true);
679 static int ovl_rename2(struct inode *olddir, struct dentry *old,
680 struct inode *newdir, struct dentry *new,
684 enum ovl_path_type old_type;
685 enum ovl_path_type new_type;
686 struct dentry *old_upperdir;
687 struct dentry *new_upperdir;
688 struct dentry *olddentry;
689 struct dentry *newdentry;
693 bool cleanup_whiteout = false;
694 bool overwrite = !(flags & RENAME_EXCHANGE);
695 bool is_dir = d_is_dir(old);
696 bool new_is_dir = false;
697 struct dentry *opaquedir = NULL;
698 const struct cred *old_cred = NULL;
701 if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
704 flags &= ~RENAME_NOREPLACE;
706 err = ovl_check_sticky(old);
710 /* Don't copy up directory trees */
711 old_type = ovl_path_type(old);
713 if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
717 err = ovl_check_sticky(new);
724 new_type = ovl_path_type(new);
726 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
730 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
731 if (ovl_dentry_lower(old)->d_inode ==
732 ovl_dentry_lower(new)->d_inode)
735 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
736 if (ovl_dentry_upper(old)->d_inode ==
737 ovl_dentry_upper(new)->d_inode)
741 if (ovl_dentry_is_opaque(new))
742 new_type = __OVL_PATH_UPPER;
744 new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
747 err = ovl_want_write(old);
751 err = ovl_copy_up(old);
755 err = ovl_copy_up(new->d_parent);
759 err = ovl_copy_up(new);
764 old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
765 new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
767 if (old_opaque || new_opaque)
768 old_cred = ovl_override_creds(old->d_sb);
770 if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
771 opaquedir = ovl_check_empty_and_clear(new);
772 err = PTR_ERR(opaquedir);
773 if (IS_ERR(opaquedir)) {
775 goto out_revert_creds;
781 if (new->d_inode || !new_opaque) {
782 /* Whiteout source */
783 flags |= RENAME_WHITEOUT;
785 /* Switch whiteouts */
786 flags |= RENAME_EXCHANGE;
788 } else if (is_dir && !new->d_inode && new_opaque) {
789 flags |= RENAME_EXCHANGE;
790 cleanup_whiteout = true;
794 old_upperdir = ovl_dentry_upper(old->d_parent);
795 new_upperdir = ovl_dentry_upper(new->d_parent);
797 trap = lock_rename(new_upperdir, old_upperdir);
800 olddentry = lookup_one_len(old->d_name.name, old_upperdir,
802 err = PTR_ERR(olddentry);
803 if (IS_ERR(olddentry))
807 if (olddentry != ovl_dentry_upper(old))
810 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
812 err = PTR_ERR(newdentry);
813 if (IS_ERR(newdentry))
817 if (ovl_dentry_upper(new)) {
819 if (newdentry != opaquedir)
822 if (newdentry != ovl_dentry_upper(new))
826 if (!d_is_negative(newdentry) &&
827 (!new_opaque || !ovl_is_whiteout(newdentry)))
831 if (olddentry == trap)
833 if (newdentry == trap)
836 if (is_dir && !old_opaque && new_opaque) {
837 err = ovl_set_opaque(olddentry);
841 if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
842 err = ovl_set_opaque(newdentry);
847 if (old_opaque || new_opaque) {
848 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
849 new_upperdir->d_inode, newdentry,
852 /* No debug for the plain case */
853 BUG_ON(flags & ~RENAME_EXCHANGE);
854 err = vfs_rename(old_upperdir->d_inode, olddentry,
855 new_upperdir->d_inode, newdentry,
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);
867 if (is_dir && old_opaque && !new_opaque)
868 ovl_remove_opaque(olddentry);
869 if (!overwrite && new_is_dir && !old_opaque && new_opaque)
870 ovl_remove_opaque(newdentry);
873 * Old dentry now lives in different location. Dentries in
874 * lowerstack are stale. We cannot drop them here because
875 * access to them is lockless. This could be only pure upper
876 * or opaque directory - numlower is zero. Or upper non-dir
877 * entry - its pureness is tracked by flag opaque.
879 if (old_opaque != new_opaque) {
880 ovl_dentry_set_opaque(old, new_opaque);
882 ovl_dentry_set_opaque(new, old_opaque);
885 if (cleanup_whiteout)
886 ovl_cleanup(old_upperdir->d_inode, newdentry);
888 ovl_dentry_version_inc(old->d_parent);
889 ovl_dentry_version_inc(new->d_parent);
896 unlock_rename(new_upperdir, old_upperdir);
898 if (old_opaque || new_opaque)
899 revert_creds(old_cred);
907 const struct inode_operations ovl_dir_inode_operations = {
908 .lookup = ovl_lookup,
910 .symlink = ovl_symlink,
911 .unlink = ovl_unlink,
913 .rename2 = ovl_rename2,
915 .setattr = ovl_setattr,
916 .create = ovl_create,
918 .permission = ovl_permission,
919 .getattr = ovl_dir_getattr,
920 .setxattr = ovl_setxattr,
921 .getxattr = ovl_getxattr,
922 .listxattr = ovl_listxattr,
923 .removexattr = ovl_removexattr,