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.
10 #include <uapi/linux/magic.h>
12 #include <linux/namei.h>
13 #include <linux/xattr.h>
14 #include <linux/mount.h>
15 #include <linux/parser.h>
16 #include <linux/module.h>
17 #include <linux/statfs.h>
18 #include <linux/seq_file.h>
19 #include <linux/posix_acl_xattr.h>
20 #include "overlayfs.h"
22 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
23 MODULE_DESCRIPTION("Overlay filesystem");
24 MODULE_LICENSE("GPL");
29 #define OVL_MAX_STACK 500
31 static bool ovl_redirect_dir_def
= IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR
);
32 module_param_named(redirect_dir
, ovl_redirect_dir_def
, bool, 0644);
33 MODULE_PARM_DESC(ovl_redirect_dir_def
,
34 "Default to on or off for the redirect_dir feature");
36 static bool ovl_index_def
= IS_ENABLED(CONFIG_OVERLAY_FS_INDEX
);
37 module_param_named(index
, ovl_index_def
, bool, 0644);
38 MODULE_PARM_DESC(ovl_index_def
,
39 "Default to on or off for the inodes index feature");
41 static void ovl_entry_stack_free(struct ovl_entry
*oe
)
45 for (i
= 0; i
< oe
->numlower
; i
++)
46 dput(oe
->lowerstack
[i
].dentry
);
49 static void ovl_dentry_release(struct dentry
*dentry
)
51 struct ovl_entry
*oe
= dentry
->d_fsdata
;
54 ovl_entry_stack_free(oe
);
59 static int ovl_check_append_only(struct inode
*inode
, int flag
)
62 * This test was moot in vfs may_open() because overlay inode does
63 * not have the S_APPEND flag, so re-check on real upper inode
65 if (IS_APPEND(inode
)) {
66 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
75 static struct dentry
*ovl_d_real(struct dentry
*dentry
,
76 const struct inode
*inode
,
77 unsigned int open_flags
, unsigned int flags
)
82 if (flags
& D_REAL_UPPER
)
83 return ovl_dentry_upper(dentry
);
85 if (!d_is_reg(dentry
)) {
86 if (!inode
|| inode
== d_inode(dentry
))
92 err
= ovl_open_maybe_copy_up(dentry
, open_flags
);
97 real
= ovl_dentry_upper(dentry
);
98 if (real
&& (!inode
|| inode
== d_inode(real
))) {
100 err
= ovl_check_append_only(d_inode(real
), open_flags
);
107 real
= ovl_dentry_lower(dentry
);
111 /* Handle recursion */
112 real
= d_real(real
, inode
, open_flags
, 0);
114 if (!inode
|| inode
== d_inode(real
))
117 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry
,
118 inode
? inode
->i_sb
->s_id
: "NULL", inode
? inode
->i_ino
: 0);
122 static int ovl_dentry_revalidate(struct dentry
*dentry
, unsigned int flags
)
124 struct ovl_entry
*oe
= dentry
->d_fsdata
;
128 for (i
= 0; i
< oe
->numlower
; i
++) {
129 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
131 if (d
->d_flags
& DCACHE_OP_REVALIDATE
) {
132 ret
= d
->d_op
->d_revalidate(d
, flags
);
136 if (!(flags
& LOOKUP_RCU
))
145 static int ovl_dentry_weak_revalidate(struct dentry
*dentry
, unsigned int flags
)
147 struct ovl_entry
*oe
= dentry
->d_fsdata
;
151 for (i
= 0; i
< oe
->numlower
; i
++) {
152 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
154 if (d
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
) {
155 ret
= d
->d_op
->d_weak_revalidate(d
, flags
);
163 static const struct dentry_operations ovl_dentry_operations
= {
164 .d_release
= ovl_dentry_release
,
165 .d_real
= ovl_d_real
,
168 static const struct dentry_operations ovl_reval_dentry_operations
= {
169 .d_release
= ovl_dentry_release
,
170 .d_real
= ovl_d_real
,
171 .d_revalidate
= ovl_dentry_revalidate
,
172 .d_weak_revalidate
= ovl_dentry_weak_revalidate
,
175 static struct kmem_cache
*ovl_inode_cachep
;
177 static struct inode
*ovl_alloc_inode(struct super_block
*sb
)
179 struct ovl_inode
*oi
= kmem_cache_alloc(ovl_inode_cachep
, GFP_KERNEL
);
188 oi
->__upperdentry
= NULL
;
190 mutex_init(&oi
->lock
);
192 return &oi
->vfs_inode
;
195 static void ovl_i_callback(struct rcu_head
*head
)
197 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
199 kmem_cache_free(ovl_inode_cachep
, OVL_I(inode
));
202 static void ovl_destroy_inode(struct inode
*inode
)
204 struct ovl_inode
*oi
= OVL_I(inode
);
206 dput(oi
->__upperdentry
);
208 ovl_dir_cache_free(inode
);
209 mutex_destroy(&oi
->lock
);
211 call_rcu(&inode
->i_rcu
, ovl_i_callback
);
214 static void ovl_free_fs(struct ovl_fs
*ofs
)
220 if (ofs
->workdir_locked
)
221 ovl_inuse_unlock(ofs
->workbasedir
);
222 dput(ofs
->workbasedir
);
223 if (ofs
->upperdir_locked
)
224 ovl_inuse_unlock(ofs
->upper_mnt
->mnt_root
);
225 mntput(ofs
->upper_mnt
);
226 for (i
= 0; i
< ofs
->numlower
; i
++) {
227 mntput(ofs
->lower_layers
[i
].mnt
);
228 free_anon_bdev(ofs
->lower_layers
[i
].pseudo_dev
);
230 kfree(ofs
->lower_layers
);
232 kfree(ofs
->config
.lowerdir
);
233 kfree(ofs
->config
.upperdir
);
234 kfree(ofs
->config
.workdir
);
235 if (ofs
->creator_cred
)
236 put_cred(ofs
->creator_cred
);
240 static void ovl_put_super(struct super_block
*sb
)
242 struct ovl_fs
*ofs
= sb
->s_fs_info
;
247 static int ovl_sync_fs(struct super_block
*sb
, int wait
)
249 struct ovl_fs
*ofs
= sb
->s_fs_info
;
250 struct super_block
*upper_sb
;
255 upper_sb
= ofs
->upper_mnt
->mnt_sb
;
256 if (!upper_sb
->s_op
->sync_fs
)
259 /* real inodes have already been synced by sync_filesystem(ovl_sb) */
260 down_read(&upper_sb
->s_umount
);
261 ret
= upper_sb
->s_op
->sync_fs(upper_sb
, wait
);
262 up_read(&upper_sb
->s_umount
);
268 * @sb: The overlayfs super block
269 * @buf: The struct kstatfs to fill in with stats
271 * Get the filesystem statistics. As writes always target the upper layer
272 * filesystem pass the statfs to the upper filesystem (if it exists)
274 static int ovl_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
276 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
277 struct dentry
*root_dentry
= dentry
->d_sb
->s_root
;
281 ovl_path_real(root_dentry
, &path
);
283 err
= vfs_statfs(&path
, buf
);
285 buf
->f_namelen
= ofs
->namelen
;
286 buf
->f_type
= OVERLAYFS_SUPER_MAGIC
;
292 /* Will this overlay be forced to mount/remount ro? */
293 static bool ovl_force_readonly(struct ovl_fs
*ofs
)
295 return (!ofs
->upper_mnt
|| !ofs
->workdir
);
301 * Prints the mount options for a given superblock.
302 * Returns zero; does not fail.
304 static int ovl_show_options(struct seq_file
*m
, struct dentry
*dentry
)
306 struct super_block
*sb
= dentry
->d_sb
;
307 struct ovl_fs
*ofs
= sb
->s_fs_info
;
309 seq_show_option(m
, "lowerdir", ofs
->config
.lowerdir
);
310 if (ofs
->config
.upperdir
) {
311 seq_show_option(m
, "upperdir", ofs
->config
.upperdir
);
312 seq_show_option(m
, "workdir", ofs
->config
.workdir
);
314 if (ofs
->config
.default_permissions
)
315 seq_puts(m
, ",default_permissions");
316 if (ofs
->config
.redirect_dir
!= ovl_redirect_dir_def
)
317 seq_printf(m
, ",redirect_dir=%s",
318 ofs
->config
.redirect_dir
? "on" : "off");
319 if (ofs
->config
.index
!= ovl_index_def
)
320 seq_printf(m
, ",index=%s",
321 ofs
->config
.index
? "on" : "off");
325 static int ovl_remount(struct super_block
*sb
, int *flags
, char *data
)
327 struct ovl_fs
*ofs
= sb
->s_fs_info
;
329 if (!(*flags
& MS_RDONLY
) && ovl_force_readonly(ofs
))
335 static const struct super_operations ovl_super_operations
= {
336 .alloc_inode
= ovl_alloc_inode
,
337 .destroy_inode
= ovl_destroy_inode
,
338 .drop_inode
= generic_delete_inode
,
339 .put_super
= ovl_put_super
,
340 .sync_fs
= ovl_sync_fs
,
341 .statfs
= ovl_statfs
,
342 .show_options
= ovl_show_options
,
343 .remount_fs
= ovl_remount
,
350 OPT_DEFAULT_PERMISSIONS
,
352 OPT_REDIRECT_DIR_OFF
,
358 static const match_table_t ovl_tokens
= {
359 {OPT_LOWERDIR
, "lowerdir=%s"},
360 {OPT_UPPERDIR
, "upperdir=%s"},
361 {OPT_WORKDIR
, "workdir=%s"},
362 {OPT_DEFAULT_PERMISSIONS
, "default_permissions"},
363 {OPT_REDIRECT_DIR_ON
, "redirect_dir=on"},
364 {OPT_REDIRECT_DIR_OFF
, "redirect_dir=off"},
365 {OPT_INDEX_ON
, "index=on"},
366 {OPT_INDEX_OFF
, "index=off"},
370 static char *ovl_next_opt(char **s
)
378 for (p
= sbegin
; *p
; p
++) {
383 } else if (*p
== ',') {
393 static int ovl_parse_opt(char *opt
, struct ovl_config
*config
)
397 while ((p
= ovl_next_opt(&opt
)) != NULL
) {
399 substring_t args
[MAX_OPT_ARGS
];
404 token
= match_token(p
, ovl_tokens
, args
);
407 kfree(config
->upperdir
);
408 config
->upperdir
= match_strdup(&args
[0]);
409 if (!config
->upperdir
)
414 kfree(config
->lowerdir
);
415 config
->lowerdir
= match_strdup(&args
[0]);
416 if (!config
->lowerdir
)
421 kfree(config
->workdir
);
422 config
->workdir
= match_strdup(&args
[0]);
423 if (!config
->workdir
)
427 case OPT_DEFAULT_PERMISSIONS
:
428 config
->default_permissions
= true;
431 case OPT_REDIRECT_DIR_ON
:
432 config
->redirect_dir
= true;
435 case OPT_REDIRECT_DIR_OFF
:
436 config
->redirect_dir
= false;
440 config
->index
= true;
444 config
->index
= false;
448 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p
);
453 /* Workdir is useless in non-upper mount */
454 if (!config
->upperdir
&& config
->workdir
) {
455 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
457 kfree(config
->workdir
);
458 config
->workdir
= NULL
;
464 #define OVL_WORKDIR_NAME "work"
465 #define OVL_INDEXDIR_NAME "index"
467 static struct dentry
*ovl_workdir_create(struct ovl_fs
*ofs
,
468 const char *name
, bool persist
)
470 struct inode
*dir
= ofs
->workbasedir
->d_inode
;
471 struct vfsmount
*mnt
= ofs
->upper_mnt
;
474 bool retried
= false;
477 err
= mnt_want_write(mnt
);
481 inode_lock_nested(dir
, I_MUTEX_PARENT
);
485 work
= lookup_one_len(name
, ofs
->workbasedir
, strlen(name
));
488 struct iattr attr
= {
489 .ia_valid
= ATTR_MODE
,
490 .ia_mode
= S_IFDIR
| 0,
502 ovl_workdir_cleanup(dir
, mnt
, work
, 0);
507 err
= ovl_create_real(dir
, work
,
508 &(struct cattr
){.mode
= S_IFDIR
| 0},
514 * Try to remove POSIX ACL xattrs from workdir. We are good if:
516 * a) success (there was a POSIX ACL xattr and was removed)
517 * b) -ENODATA (there was no POSIX ACL xattr)
518 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
520 * There are various other error values that could effectively
521 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
522 * if the xattr name is too long), but the set of filesystems
523 * allowed as upper are limited to "normal" ones, where checking
524 * for the above two errors is sufficient.
526 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_DEFAULT
);
527 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
530 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_ACCESS
);
531 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
534 /* Clear any inherited mode bits */
535 inode_lock(work
->d_inode
);
536 err
= notify_change(work
, &attr
, NULL
);
537 inode_unlock(work
->d_inode
);
554 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
555 ofs
->config
.workdir
, name
, -err
);
560 static void ovl_unescape(char *s
)
573 static int ovl_mount_dir_noesc(const char *name
, struct path
*path
)
578 pr_err("overlayfs: empty lowerdir\n");
581 err
= kern_path(name
, LOOKUP_FOLLOW
, path
);
583 pr_err("overlayfs: failed to resolve '%s': %i\n", name
, err
);
587 if (ovl_dentry_weird(path
->dentry
)) {
588 pr_err("overlayfs: filesystem on '%s' not supported\n", name
);
591 if (!d_is_dir(path
->dentry
)) {
592 pr_err("overlayfs: '%s' not a directory\n", name
);
603 static int ovl_mount_dir(const char *name
, struct path
*path
)
606 char *tmp
= kstrdup(name
, GFP_KERNEL
);
610 err
= ovl_mount_dir_noesc(tmp
, path
);
613 if (ovl_dentry_remote(path
->dentry
)) {
614 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
624 static int ovl_check_namelen(struct path
*path
, struct ovl_fs
*ofs
,
627 struct kstatfs statfs
;
628 int err
= vfs_statfs(path
, &statfs
);
631 pr_err("overlayfs: statfs failed on '%s'\n", name
);
633 ofs
->namelen
= max(ofs
->namelen
, statfs
.f_namelen
);
638 static int ovl_lower_dir(const char *name
, struct path
*path
,
639 struct ovl_fs
*ofs
, int *stack_depth
, bool *remote
)
643 err
= ovl_mount_dir_noesc(name
, path
);
647 err
= ovl_check_namelen(path
, ofs
, name
);
651 *stack_depth
= max(*stack_depth
, path
->mnt
->mnt_sb
->s_stack_depth
);
653 if (ovl_dentry_remote(path
->dentry
))
657 * The inodes index feature needs to encode and decode file
658 * handles, so it requires that all layers support them.
660 if (ofs
->config
.index
&& !ovl_can_decode_fh(path
->dentry
->d_sb
)) {
661 ofs
->config
.index
= false;
662 pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off.\n", name
);
673 /* Workdir should not be subdir of upperdir and vice versa */
674 static bool ovl_workdir_ok(struct dentry
*workdir
, struct dentry
*upperdir
)
678 if (workdir
!= upperdir
) {
679 ok
= (lock_rename(workdir
, upperdir
) == NULL
);
680 unlock_rename(workdir
, upperdir
);
685 static unsigned int ovl_split_lowerdirs(char *str
)
687 unsigned int ctr
= 1;
690 for (s
= d
= str
;; s
++, d
++) {
693 } else if (*s
== ':') {
705 static int __maybe_unused
706 ovl_posix_acl_xattr_get(const struct xattr_handler
*handler
,
707 struct dentry
*dentry
, struct inode
*inode
,
708 const char *name
, void *buffer
, size_t size
)
710 return ovl_xattr_get(dentry
, inode
, handler
->name
, buffer
, size
);
713 static int __maybe_unused
714 ovl_posix_acl_xattr_set(const struct xattr_handler
*handler
,
715 struct dentry
*dentry
, struct inode
*inode
,
716 const char *name
, const void *value
,
717 size_t size
, int flags
)
719 struct dentry
*workdir
= ovl_workdir(dentry
);
720 struct inode
*realinode
= ovl_inode_real(inode
);
721 struct posix_acl
*acl
= NULL
;
724 /* Check that everything is OK before copy-up */
726 acl
= posix_acl_from_xattr(&init_user_ns
, value
, size
);
731 if (!IS_POSIXACL(d_inode(workdir
)))
732 goto out_acl_release
;
733 if (!realinode
->i_op
->set_acl
)
734 goto out_acl_release
;
735 if (handler
->flags
== ACL_TYPE_DEFAULT
&& !S_ISDIR(inode
->i_mode
)) {
736 err
= acl
? -EACCES
: 0;
737 goto out_acl_release
;
740 if (!inode_owner_or_capable(inode
))
741 goto out_acl_release
;
743 posix_acl_release(acl
);
746 * Check if sgid bit needs to be cleared (actual setacl operation will
747 * be done with mounter's capabilities and so that won't do it for us).
749 if (unlikely(inode
->i_mode
& S_ISGID
) &&
750 handler
->flags
== ACL_TYPE_ACCESS
&&
751 !in_group_p(inode
->i_gid
) &&
752 !capable_wrt_inode_uidgid(inode
, CAP_FSETID
)) {
753 struct iattr iattr
= { .ia_valid
= ATTR_KILL_SGID
};
755 err
= ovl_setattr(dentry
, &iattr
);
760 err
= ovl_xattr_set(dentry
, inode
, handler
->name
, value
, size
, flags
);
762 ovl_copyattr(ovl_inode_real(inode
), inode
);
767 posix_acl_release(acl
);
771 static int ovl_own_xattr_get(const struct xattr_handler
*handler
,
772 struct dentry
*dentry
, struct inode
*inode
,
773 const char *name
, void *buffer
, size_t size
)
778 static int ovl_own_xattr_set(const struct xattr_handler
*handler
,
779 struct dentry
*dentry
, struct inode
*inode
,
780 const char *name
, const void *value
,
781 size_t size
, int flags
)
786 static int ovl_other_xattr_get(const struct xattr_handler
*handler
,
787 struct dentry
*dentry
, struct inode
*inode
,
788 const char *name
, void *buffer
, size_t size
)
790 return ovl_xattr_get(dentry
, inode
, name
, buffer
, size
);
793 static int ovl_other_xattr_set(const struct xattr_handler
*handler
,
794 struct dentry
*dentry
, struct inode
*inode
,
795 const char *name
, const void *value
,
796 size_t size
, int flags
)
798 return ovl_xattr_set(dentry
, inode
, name
, value
, size
, flags
);
801 static const struct xattr_handler __maybe_unused
802 ovl_posix_acl_access_xattr_handler
= {
803 .name
= XATTR_NAME_POSIX_ACL_ACCESS
,
804 .flags
= ACL_TYPE_ACCESS
,
805 .get
= ovl_posix_acl_xattr_get
,
806 .set
= ovl_posix_acl_xattr_set
,
809 static const struct xattr_handler __maybe_unused
810 ovl_posix_acl_default_xattr_handler
= {
811 .name
= XATTR_NAME_POSIX_ACL_DEFAULT
,
812 .flags
= ACL_TYPE_DEFAULT
,
813 .get
= ovl_posix_acl_xattr_get
,
814 .set
= ovl_posix_acl_xattr_set
,
817 static const struct xattr_handler ovl_own_xattr_handler
= {
818 .prefix
= OVL_XATTR_PREFIX
,
819 .get
= ovl_own_xattr_get
,
820 .set
= ovl_own_xattr_set
,
823 static const struct xattr_handler ovl_other_xattr_handler
= {
824 .prefix
= "", /* catch all */
825 .get
= ovl_other_xattr_get
,
826 .set
= ovl_other_xattr_set
,
829 static const struct xattr_handler
*ovl_xattr_handlers
[] = {
830 #ifdef CONFIG_FS_POSIX_ACL
831 &ovl_posix_acl_access_xattr_handler
,
832 &ovl_posix_acl_default_xattr_handler
,
834 &ovl_own_xattr_handler
,
835 &ovl_other_xattr_handler
,
839 static int ovl_get_upper(struct ovl_fs
*ofs
, struct path
*upperpath
)
841 struct vfsmount
*upper_mnt
;
844 err
= ovl_mount_dir(ofs
->config
.upperdir
, upperpath
);
848 /* Upper fs should not be r/o */
849 if (sb_rdonly(upperpath
->mnt
->mnt_sb
)) {
850 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
855 err
= ovl_check_namelen(upperpath
, ofs
, ofs
->config
.upperdir
);
860 if (ovl_inuse_trylock(upperpath
->dentry
)) {
861 ofs
->upperdir_locked
= true;
862 } else if (ofs
->config
.index
) {
863 pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");
866 pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
869 upper_mnt
= clone_private_mount(upperpath
);
870 err
= PTR_ERR(upper_mnt
);
871 if (IS_ERR(upper_mnt
)) {
872 pr_err("overlayfs: failed to clone upperpath\n");
876 /* Don't inherit atime flags */
877 upper_mnt
->mnt_flags
&= ~(MNT_NOATIME
| MNT_NODIRATIME
| MNT_RELATIME
);
878 ofs
->upper_mnt
= upper_mnt
;
884 static int ovl_make_workdir(struct ovl_fs
*ofs
, struct path
*workpath
)
889 ofs
->workdir
= ovl_workdir_create(ofs
, OVL_WORKDIR_NAME
, false);
894 * Upper should support d_type, else whiteouts are visible. Given
895 * workdir and upper are on same fs, we can do iterate_dir() on
896 * workdir. This check requires successful creation of workdir in
899 err
= ovl_check_d_type_supported(workpath
);
904 * We allowed this configuration and don't want to break users over
905 * kernel upgrade. So warn instead of erroring out.
908 pr_warn("overlayfs: upper fs needs to support d_type.\n");
910 /* Check if upper/work fs supports O_TMPFILE */
911 temp
= ovl_do_tmpfile(ofs
->workdir
, S_IFREG
| 0);
912 ofs
->tmpfile
= !IS_ERR(temp
);
916 pr_warn("overlayfs: upper fs does not support tmpfile.\n");
919 * Check if upper/work fs supports trusted.overlay.* xattr
921 err
= ovl_do_setxattr(ofs
->workdir
, OVL_XATTR_OPAQUE
, "0", 1, 0);
924 pr_warn("overlayfs: upper fs does not support xattr.\n");
926 vfs_removexattr(ofs
->workdir
, OVL_XATTR_OPAQUE
);
929 /* Check if upper/work fs supports file handles */
930 if (ofs
->config
.index
&&
931 !ovl_can_decode_fh(ofs
->workdir
->d_sb
)) {
932 ofs
->config
.index
= false;
933 pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
939 static int ovl_get_workdir(struct ovl_fs
*ofs
, struct path
*upperpath
)
942 struct path workpath
= { };
944 err
= ovl_mount_dir(ofs
->config
.workdir
, &workpath
);
949 if (upperpath
->mnt
!= workpath
.mnt
) {
950 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
953 if (!ovl_workdir_ok(workpath
.dentry
, upperpath
->dentry
)) {
954 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
959 if (ovl_inuse_trylock(workpath
.dentry
)) {
960 ofs
->workdir_locked
= true;
961 } else if (ofs
->config
.index
) {
962 pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n");
965 pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
968 ofs
->workbasedir
= dget(workpath
.dentry
);
969 err
= ovl_make_workdir(ofs
, &workpath
);
980 static int ovl_get_indexdir(struct ovl_fs
*ofs
, struct ovl_entry
*oe
,
981 struct path
*upperpath
)
985 /* Verify lower root is upper root origin */
986 err
= ovl_verify_origin(upperpath
->dentry
, oe
->lowerstack
[0].dentry
,
989 pr_err("overlayfs: failed to verify upper root origin\n");
993 ofs
->indexdir
= ovl_workdir_create(ofs
, OVL_INDEXDIR_NAME
, true);
995 /* Verify upper root is index dir origin */
996 err
= ovl_verify_origin(ofs
->indexdir
, upperpath
->dentry
,
999 pr_err("overlayfs: failed to verify index dir origin\n");
1001 /* Cleanup bad/stale/orphan index entries */
1003 err
= ovl_indexdir_cleanup(ofs
->indexdir
,
1008 if (err
|| !ofs
->indexdir
)
1009 pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1015 static int ovl_get_lower_layers(struct ovl_fs
*ofs
, struct path
*stack
,
1016 unsigned int numlower
)
1022 ofs
->lower_layers
= kcalloc(numlower
, sizeof(struct ovl_layer
),
1024 if (ofs
->lower_layers
== NULL
)
1026 for (i
= 0; i
< numlower
; i
++) {
1027 struct vfsmount
*mnt
;
1030 err
= get_anon_bdev(&dev
);
1032 pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
1036 mnt
= clone_private_mount(&stack
[i
]);
1039 pr_err("overlayfs: failed to clone lowerpath\n");
1040 free_anon_bdev(dev
);
1044 * Make lower layers R/O. That way fchmod/fchown on lower file
1045 * will fail instead of modifying lower fs.
1047 mnt
->mnt_flags
|= MNT_READONLY
| MNT_NOATIME
;
1049 ofs
->lower_layers
[ofs
->numlower
].mnt
= mnt
;
1050 ofs
->lower_layers
[ofs
->numlower
].pseudo_dev
= dev
;
1053 /* Check if all lower layers are on same sb */
1055 ofs
->same_sb
= mnt
->mnt_sb
;
1056 else if (ofs
->same_sb
!= mnt
->mnt_sb
)
1057 ofs
->same_sb
= NULL
;
1064 static struct ovl_entry
*ovl_get_lowerstack(struct super_block
*sb
,
1068 char *lowertmp
, *lower
;
1069 struct path
*stack
= NULL
;
1070 unsigned int stacklen
, numlower
= 0, i
;
1071 bool remote
= false;
1072 struct ovl_entry
*oe
;
1075 lowertmp
= kstrdup(ofs
->config
.lowerdir
, GFP_KERNEL
);
1080 stacklen
= ovl_split_lowerdirs(lowertmp
);
1081 if (stacklen
> OVL_MAX_STACK
) {
1082 pr_err("overlayfs: too many lower directories, limit is %d\n",
1085 } else if (!ofs
->config
.upperdir
&& stacklen
== 1) {
1086 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
1091 stack
= kcalloc(stacklen
, sizeof(struct path
), GFP_KERNEL
);
1097 for (numlower
= 0; numlower
< stacklen
; numlower
++) {
1098 err
= ovl_lower_dir(lower
, &stack
[numlower
], ofs
,
1099 &sb
->s_stack_depth
, &remote
);
1103 lower
= strchr(lower
, '\0') + 1;
1107 sb
->s_stack_depth
++;
1108 if (sb
->s_stack_depth
> FILESYSTEM_MAX_STACK_DEPTH
) {
1109 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
1113 err
= ovl_get_lower_layers(ofs
, stack
, numlower
);
1118 oe
= ovl_alloc_entry(numlower
);
1122 for (i
= 0; i
< numlower
; i
++) {
1123 oe
->lowerstack
[i
].dentry
= dget(stack
[i
].dentry
);
1124 oe
->lowerstack
[i
].layer
= &ofs
->lower_layers
[i
];
1128 sb
->s_d_op
= &ovl_reval_dentry_operations
;
1130 sb
->s_d_op
= &ovl_dentry_operations
;
1133 for (i
= 0; i
< numlower
; i
++)
1134 path_put(&stack
[i
]);
1145 static int ovl_fill_super(struct super_block
*sb
, void *data
, int silent
)
1147 struct path upperpath
= { };
1148 struct dentry
*root_dentry
;
1149 struct ovl_entry
*oe
;
1155 ofs
= kzalloc(sizeof(struct ovl_fs
), GFP_KERNEL
);
1159 ofs
->creator_cred
= cred
= prepare_creds();
1163 ofs
->config
.redirect_dir
= ovl_redirect_dir_def
;
1164 ofs
->config
.index
= ovl_index_def
;
1165 err
= ovl_parse_opt((char *) data
, &ofs
->config
);
1170 if (!ofs
->config
.lowerdir
) {
1172 pr_err("overlayfs: missing 'lowerdir'\n");
1176 sb
->s_stack_depth
= 0;
1177 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
1178 if (ofs
->config
.upperdir
) {
1179 if (!ofs
->config
.workdir
) {
1180 pr_err("overlayfs: missing 'workdir'\n");
1184 err
= ovl_get_upper(ofs
, &upperpath
);
1188 err
= ovl_get_workdir(ofs
, &upperpath
);
1193 sb
->s_flags
|= MS_RDONLY
;
1195 sb
->s_stack_depth
= ofs
->upper_mnt
->mnt_sb
->s_stack_depth
;
1196 sb
->s_time_gran
= ofs
->upper_mnt
->mnt_sb
->s_time_gran
;
1199 oe
= ovl_get_lowerstack(sb
, ofs
);
1204 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1205 if (!ofs
->upper_mnt
)
1206 sb
->s_flags
|= MS_RDONLY
;
1207 else if (ofs
->upper_mnt
->mnt_sb
!= ofs
->same_sb
)
1208 ofs
->same_sb
= NULL
;
1210 if (!(ovl_force_readonly(ofs
)) && ofs
->config
.index
) {
1211 err
= ovl_get_indexdir(ofs
, oe
, &upperpath
);
1216 sb
->s_flags
|= MS_RDONLY
;
1219 /* Show index=off/on in /proc/mounts for any of the reasons above */
1221 ofs
->config
.index
= false;
1223 /* Never override disk quota limits or use reserved space */
1224 cap_lower(cred
->cap_effective
, CAP_SYS_RESOURCE
);
1226 sb
->s_magic
= OVERLAYFS_SUPER_MAGIC
;
1227 sb
->s_op
= &ovl_super_operations
;
1228 sb
->s_xattr
= ovl_xattr_handlers
;
1229 sb
->s_fs_info
= ofs
;
1230 sb
->s_flags
|= MS_POSIXACL
| MS_NOREMOTELOCK
;
1233 root_dentry
= d_make_root(ovl_new_inode(sb
, S_IFDIR
, 0));
1237 mntput(upperpath
.mnt
);
1238 if (upperpath
.dentry
) {
1239 oe
->has_upper
= true;
1240 if (ovl_is_impuredir(upperpath
.dentry
))
1241 ovl_set_flag(OVL_IMPURE
, d_inode(root_dentry
));
1244 root_dentry
->d_fsdata
= oe
;
1246 /* Root is always merge -> can have whiteouts */
1247 ovl_set_flag(OVL_WHITEOUTS
, d_inode(root_dentry
));
1248 ovl_inode_init(d_inode(root_dentry
), upperpath
.dentry
,
1249 ovl_dentry_lower(root_dentry
));
1251 sb
->s_root
= root_dentry
;
1256 ovl_entry_stack_free(oe
);
1259 path_put(&upperpath
);
1265 static struct dentry
*ovl_mount(struct file_system_type
*fs_type
, int flags
,
1266 const char *dev_name
, void *raw_data
)
1268 return mount_nodev(fs_type
, flags
, raw_data
, ovl_fill_super
);
1271 static struct file_system_type ovl_fs_type
= {
1272 .owner
= THIS_MODULE
,
1275 .kill_sb
= kill_anon_super
,
1277 MODULE_ALIAS_FS("overlay");
1279 static void ovl_inode_init_once(void *foo
)
1281 struct ovl_inode
*oi
= foo
;
1283 inode_init_once(&oi
->vfs_inode
);
1286 static int __init
ovl_init(void)
1290 ovl_inode_cachep
= kmem_cache_create("ovl_inode",
1291 sizeof(struct ovl_inode
), 0,
1292 (SLAB_RECLAIM_ACCOUNT
|
1293 SLAB_MEM_SPREAD
|SLAB_ACCOUNT
),
1294 ovl_inode_init_once
);
1295 if (ovl_inode_cachep
== NULL
)
1298 err
= register_filesystem(&ovl_fs_type
);
1300 kmem_cache_destroy(ovl_inode_cachep
);
1305 static void __exit
ovl_exit(void)
1307 unregister_filesystem(&ovl_fs_type
);
1310 * Make sure all delayed rcu free inodes are flushed before we
1314 kmem_cache_destroy(ovl_inode_cachep
);
1318 module_init(ovl_init
);
1319 module_exit(ovl_exit
);