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 static int ovl_create_upper(struct dentry
*dentry
, struct inode
*inode
,
162 struct kstat
*stat
, const char *link
,
163 struct dentry
*hardlink
)
165 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
166 struct inode
*udir
= upperdir
->d_inode
;
167 struct dentry
*newdentry
;
170 inode_lock_nested(udir
, I_MUTEX_PARENT
);
171 newdentry
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
173 err
= PTR_ERR(newdentry
);
174 if (IS_ERR(newdentry
))
176 err
= ovl_create_real(udir
, newdentry
, stat
, link
, hardlink
, false);
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
);
192 static int ovl_lock_rename_workdir(struct dentry
*workdir
,
193 struct dentry
*upperdir
)
195 /* Workdir should not be the same as upperdir */
196 if (workdir
== upperdir
)
199 /* Workdir should not be subdir of upperdir and vice versa */
200 if (lock_rename(workdir
, upperdir
) != NULL
)
206 unlock_rename(workdir
, upperdir
);
208 pr_err("overlayfs: failed to lock workdir+upperdir\n");
212 static struct dentry
*ovl_clear_empty(struct dentry
*dentry
,
213 struct list_head
*list
)
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
;
225 if (WARN_ON(!workdir
))
226 return ERR_PTR(-EROFS
);
228 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
232 ovl_path_upper(dentry
, &upperpath
);
233 err
= vfs_getattr(&upperpath
, &stat
);
238 if (!S_ISDIR(stat
.mode
))
240 upper
= upperpath
.dentry
;
241 if (upper
->d_parent
->d_inode
!= udir
)
244 opaquedir
= ovl_lookup_temp(workdir
, dentry
);
245 err
= PTR_ERR(opaquedir
);
246 if (IS_ERR(opaquedir
))
249 err
= ovl_create_real(wdir
, opaquedir
, &stat
, NULL
, NULL
, true);
253 err
= ovl_copy_xattr(upper
, opaquedir
);
257 err
= ovl_set_opaque(opaquedir
);
261 inode_lock(opaquedir
->d_inode
);
262 err
= ovl_set_attr(opaquedir
, &stat
);
263 inode_unlock(opaquedir
->d_inode
);
267 err
= ovl_do_rename(wdir
, opaquedir
, udir
, upper
, RENAME_EXCHANGE
);
271 ovl_cleanup_whiteouts(upper
, list
);
272 ovl_cleanup(wdir
, upper
);
273 unlock_rename(workdir
, upperdir
);
275 /* dentry's upper doesn't match now, get rid of it */
281 ovl_cleanup(wdir
, opaquedir
);
285 unlock_rename(workdir
, upperdir
);
290 static struct dentry
*ovl_check_empty_and_clear(struct dentry
*dentry
)
293 struct dentry
*ret
= NULL
;
296 err
= ovl_check_empty_dir(dentry
, &list
);
301 * If no upperdentry then skip clearing whiteouts.
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.
307 if (ovl_dentry_upper(dentry
))
308 ret
= ovl_clear_empty(dentry
, &list
);
311 ovl_cache_free(&list
);
316 static int ovl_create_over_whiteout(struct dentry
*dentry
, struct inode
*inode
,
317 struct kstat
*stat
, const char *link
,
318 struct dentry
*hardlink
)
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
;
328 if (WARN_ON(!workdir
))
331 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
335 newdentry
= ovl_lookup_temp(workdir
, dentry
);
336 err
= PTR_ERR(newdentry
);
337 if (IS_ERR(newdentry
))
340 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
342 err
= PTR_ERR(upper
);
346 err
= ovl_create_real(wdir
, newdentry
, stat
, link
, hardlink
, true);
350 if (S_ISDIR(stat
->mode
)) {
351 err
= ovl_set_opaque(newdentry
);
355 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
,
360 ovl_cleanup(wdir
, upper
);
362 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
, 0);
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
);
376 unlock_rename(workdir
, upperdir
);
381 ovl_cleanup(wdir
, newdentry
);
385 static int ovl_create_or_link(struct dentry
*dentry
, int mode
, dev_t rdev
,
386 const char *link
, struct dentry
*hardlink
)
390 struct kstat stat
= {
396 inode
= ovl_new_inode(dentry
->d_sb
, mode
, dentry
->d_fsdata
);
400 err
= ovl_copy_up(dentry
->d_parent
);
404 if (!ovl_dentry_is_opaque(dentry
)) {
405 err
= ovl_create_upper(dentry
, inode
, &stat
, link
, hardlink
);
407 const struct cred
*old_cred
;
409 old_cred
= ovl_override_creds(dentry
->d_sb
);
411 err
= ovl_create_over_whiteout(dentry
, inode
, &stat
, link
,
414 revert_creds(old_cred
);
425 static int ovl_create_object(struct dentry
*dentry
, int mode
, dev_t rdev
,
430 err
= ovl_want_write(dentry
);
432 err
= ovl_create_or_link(dentry
, mode
, rdev
, link
, NULL
);
433 ovl_drop_write(dentry
);
439 static int ovl_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
442 return ovl_create_object(dentry
, (mode
& 07777) | S_IFREG
, 0, NULL
);
445 static int ovl_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
447 return ovl_create_object(dentry
, (mode
& 07777) | S_IFDIR
, 0, NULL
);
450 static int ovl_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
453 /* Don't allow creation of "whiteout" on overlay */
454 if (S_ISCHR(mode
) && rdev
== WHITEOUT_DEV
)
457 return ovl_create_object(dentry
, mode
, rdev
, NULL
);
460 static int ovl_symlink(struct inode
*dir
, struct dentry
*dentry
,
463 return ovl_create_object(dentry
, S_IFLNK
, 0, link
);
466 static int ovl_link(struct dentry
*old
, struct inode
*newdir
,
470 struct dentry
*upper
;
472 err
= ovl_want_write(old
);
476 err
= ovl_copy_up(old
);
480 upper
= ovl_dentry_upper(old
);
481 err
= ovl_create_or_link(new, upper
->d_inode
->i_mode
, 0, NULL
, upper
);
489 static int ovl_remove_and_whiteout(struct dentry
*dentry
, bool is_dir
)
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
;
500 if (WARN_ON(!workdir
))
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
))
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.
517 err
= ovl_check_empty_dir(dentry
, &list
);
518 ovl_cache_free(&list
);
524 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
528 whiteout
= ovl_whiteout(workdir
, dentry
);
529 err
= PTR_ERR(whiteout
);
530 if (IS_ERR(whiteout
))
533 upper
= ovl_dentry_upper(dentry
);
535 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
537 err
= PTR_ERR(upper
);
541 err
= ovl_do_rename(wdir
, whiteout
, udir
, upper
, 0);
551 if (upper
->d_parent
!= upperdir
)
555 flags
|= RENAME_EXCHANGE
;
557 err
= ovl_do_rename(wdir
, whiteout
, udir
, upper
, flags
);
562 ovl_cleanup(wdir
, upper
);
564 ovl_dentry_version_inc(dentry
->d_parent
);
569 unlock_rename(workdir
, upperdir
);
576 ovl_cleanup(wdir
, whiteout
);
580 static int ovl_remove_upper(struct dentry
*dentry
, bool is_dir
)
582 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
583 struct inode
*dir
= upperdir
->d_inode
;
584 struct dentry
*upper
;
587 inode_lock_nested(dir
, I_MUTEX_PARENT
);
588 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
590 err
= PTR_ERR(upper
);
595 if (upper
== ovl_dentry_upper(dentry
)) {
597 err
= vfs_rmdir(dir
, upper
);
599 err
= vfs_unlink(dir
, upper
, NULL
);
600 ovl_dentry_version_inc(dentry
->d_parent
);
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
618 static inline int ovl_check_sticky(struct dentry
*dentry
)
620 struct inode
*dir
= ovl_dentry_real(dentry
->d_parent
)->d_inode
;
621 struct inode
*inode
= ovl_dentry_real(dentry
)->d_inode
;
623 if (check_sticky(dir
, inode
))
629 static int ovl_do_remove(struct dentry
*dentry
, bool is_dir
)
631 enum ovl_path_type type
;
634 err
= ovl_check_sticky(dentry
);
638 err
= ovl_want_write(dentry
);
642 err
= ovl_copy_up(dentry
->d_parent
);
646 type
= ovl_path_type(dentry
);
647 if (OVL_TYPE_PURE_UPPER(type
)) {
648 err
= ovl_remove_upper(dentry
, is_dir
);
650 const struct cred
*old_cred
= ovl_override_creds(dentry
->d_sb
);
652 err
= ovl_remove_and_whiteout(dentry
, is_dir
);
654 revert_creds(old_cred
);
657 ovl_drop_write(dentry
);
662 static int ovl_unlink(struct inode
*dir
, struct dentry
*dentry
)
664 return ovl_do_remove(dentry
, false);
667 static int ovl_rmdir(struct inode
*dir
, struct dentry
*dentry
)
669 return ovl_do_remove(dentry
, true);
672 static int ovl_rename2(struct inode
*olddir
, struct dentry
*old
,
673 struct inode
*newdir
, struct dentry
*new,
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
;
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
;
694 if (flags
& ~(RENAME_EXCHANGE
| RENAME_NOREPLACE
))
697 flags
&= ~RENAME_NOREPLACE
;
699 err
= ovl_check_sticky(old
);
703 /* Don't copy up directory trees */
704 old_type
= ovl_path_type(old
);
706 if (OVL_TYPE_MERGE_OR_LOWER(old_type
) && is_dir
)
710 err
= ovl_check_sticky(new);
717 new_type
= ovl_path_type(new);
719 if (!overwrite
&& OVL_TYPE_MERGE_OR_LOWER(new_type
) && new_is_dir
)
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
)
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
)
734 if (ovl_dentry_is_opaque(new))
735 new_type
= __OVL_PATH_UPPER
;
737 new_type
= __OVL_PATH_UPPER
| __OVL_PATH_PURE
;
740 err
= ovl_want_write(old
);
744 err
= ovl_copy_up(old
);
748 err
= ovl_copy_up(new->d_parent
);
752 err
= ovl_copy_up(new);
757 old_opaque
= !OVL_TYPE_PURE_UPPER(old_type
);
758 new_opaque
= !OVL_TYPE_PURE_UPPER(new_type
);
760 if (old_opaque
|| new_opaque
)
761 old_cred
= ovl_override_creds(old
->d_sb
);
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
)) {
768 goto out_revert_creds
;
774 if (new->d_inode
|| !new_opaque
) {
775 /* Whiteout source */
776 flags
|= RENAME_WHITEOUT
;
778 /* Switch whiteouts */
779 flags
|= RENAME_EXCHANGE
;
781 } else if (is_dir
&& !new->d_inode
&& new_opaque
) {
782 flags
|= RENAME_EXCHANGE
;
783 cleanup_whiteout
= true;
787 old_upperdir
= ovl_dentry_upper(old
->d_parent
);
788 new_upperdir
= ovl_dentry_upper(new->d_parent
);
790 trap
= lock_rename(new_upperdir
, old_upperdir
);
793 olddentry
= lookup_one_len(old
->d_name
.name
, old_upperdir
,
795 err
= PTR_ERR(olddentry
);
796 if (IS_ERR(olddentry
))
800 if (olddentry
!= ovl_dentry_upper(old
))
803 newdentry
= lookup_one_len(new->d_name
.name
, new_upperdir
,
805 err
= PTR_ERR(newdentry
);
806 if (IS_ERR(newdentry
))
810 if (ovl_dentry_upper(new)) {
812 if (newdentry
!= opaquedir
)
815 if (newdentry
!= ovl_dentry_upper(new))
819 if (!d_is_negative(newdentry
) &&
820 (!new_opaque
|| !ovl_is_whiteout(newdentry
)))
824 if (olddentry
== trap
)
826 if (newdentry
== trap
)
829 if (is_dir
&& !old_opaque
&& new_opaque
) {
830 err
= ovl_set_opaque(olddentry
);
834 if (!overwrite
&& new_is_dir
&& old_opaque
&& !new_opaque
) {
835 err
= ovl_set_opaque(newdentry
);
840 if (old_opaque
|| new_opaque
) {
841 err
= ovl_do_rename(old_upperdir
->d_inode
, olddentry
,
842 new_upperdir
->d_inode
, newdentry
,
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
,
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
);
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
);
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.
872 if (old_opaque
!= new_opaque
) {
873 ovl_dentry_set_opaque(old
, new_opaque
);
875 ovl_dentry_set_opaque(new, old_opaque
);
878 if (cleanup_whiteout
)
879 ovl_cleanup(old_upperdir
->d_inode
, newdentry
);
881 ovl_dentry_version_inc(old
->d_parent
);
882 ovl_dentry_version_inc(new->d_parent
);
889 unlock_rename(new_upperdir
, old_upperdir
);
891 if (old_opaque
|| new_opaque
)
892 revert_creds(old_cred
);
900 const struct inode_operations ovl_dir_inode_operations
= {
901 .lookup
= ovl_lookup
,
903 .symlink
= ovl_symlink
,
904 .unlink
= ovl_unlink
,
906 .rename2
= ovl_rename2
,
908 .setattr
= ovl_setattr
,
909 .create
= ovl_create
,
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
,