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"
21 #include "ovl_entry.h"
23 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
24 MODULE_DESCRIPTION("Overlay filesystem");
25 MODULE_LICENSE("GPL");
30 #define OVL_MAX_STACK 500
32 static bool ovl_redirect_dir_def
= IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR
);
33 module_param_named(redirect_dir
, ovl_redirect_dir_def
, bool, 0644);
34 MODULE_PARM_DESC(ovl_redirect_dir_def
,
35 "Default to on or off for the redirect_dir feature");
37 static void ovl_dentry_release(struct dentry
*dentry
)
39 struct ovl_entry
*oe
= dentry
->d_fsdata
;
44 dput(oe
->__upperdentry
);
46 for (i
= 0; i
< oe
->numlower
; i
++)
47 dput(oe
->lowerstack
[i
].dentry
);
52 static int ovl_check_append_only(struct inode
*inode
, int flag
)
55 * This test was moot in vfs may_open() because overlay inode does
56 * not have the S_APPEND flag, so re-check on real upper inode
58 if (IS_APPEND(inode
)) {
59 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
68 static struct dentry
*ovl_d_real(struct dentry
*dentry
,
69 const struct inode
*inode
,
70 unsigned int open_flags
)
75 if (!d_is_reg(dentry
)) {
76 if (!inode
|| inode
== d_inode(dentry
))
81 if (d_is_negative(dentry
))
85 err
= ovl_open_maybe_copy_up(dentry
, open_flags
);
90 real
= ovl_dentry_upper(dentry
);
91 if (real
&& (!inode
|| inode
== d_inode(real
))) {
93 err
= ovl_check_append_only(d_inode(real
), open_flags
);
100 real
= ovl_dentry_lower(dentry
);
104 /* Handle recursion */
105 real
= d_real(real
, inode
, open_flags
);
107 if (!inode
|| inode
== d_inode(real
))
110 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry
,
111 inode
? inode
->i_sb
->s_id
: "NULL", inode
? inode
->i_ino
: 0);
115 static int ovl_dentry_revalidate(struct dentry
*dentry
, unsigned int flags
)
117 struct ovl_entry
*oe
= dentry
->d_fsdata
;
121 for (i
= 0; i
< oe
->numlower
; i
++) {
122 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
124 if (d
->d_flags
& DCACHE_OP_REVALIDATE
) {
125 ret
= d
->d_op
->d_revalidate(d
, flags
);
129 if (!(flags
& LOOKUP_RCU
))
138 static int ovl_dentry_weak_revalidate(struct dentry
*dentry
, unsigned int flags
)
140 struct ovl_entry
*oe
= dentry
->d_fsdata
;
144 for (i
= 0; i
< oe
->numlower
; i
++) {
145 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
147 if (d
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
) {
148 ret
= d
->d_op
->d_weak_revalidate(d
, flags
);
156 static const struct dentry_operations ovl_dentry_operations
= {
157 .d_release
= ovl_dentry_release
,
158 .d_real
= ovl_d_real
,
161 static const struct dentry_operations ovl_reval_dentry_operations
= {
162 .d_release
= ovl_dentry_release
,
163 .d_real
= ovl_d_real
,
164 .d_revalidate
= ovl_dentry_revalidate
,
165 .d_weak_revalidate
= ovl_dentry_weak_revalidate
,
168 static void ovl_put_super(struct super_block
*sb
)
170 struct ovl_fs
*ufs
= sb
->s_fs_info
;
174 mntput(ufs
->upper_mnt
);
175 for (i
= 0; i
< ufs
->numlower
; i
++)
176 mntput(ufs
->lower_mnt
[i
]);
177 kfree(ufs
->lower_mnt
);
179 kfree(ufs
->config
.lowerdir
);
180 kfree(ufs
->config
.upperdir
);
181 kfree(ufs
->config
.workdir
);
182 put_cred(ufs
->creator_cred
);
186 static int ovl_sync_fs(struct super_block
*sb
, int wait
)
188 struct ovl_fs
*ufs
= sb
->s_fs_info
;
189 struct super_block
*upper_sb
;
194 upper_sb
= ufs
->upper_mnt
->mnt_sb
;
195 if (!upper_sb
->s_op
->sync_fs
)
198 /* real inodes have already been synced by sync_filesystem(ovl_sb) */
199 down_read(&upper_sb
->s_umount
);
200 ret
= upper_sb
->s_op
->sync_fs(upper_sb
, wait
);
201 up_read(&upper_sb
->s_umount
);
207 * @sb: The overlayfs super block
208 * @buf: The struct kstatfs to fill in with stats
210 * Get the filesystem statistics. As writes always target the upper layer
211 * filesystem pass the statfs to the upper filesystem (if it exists)
213 static int ovl_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
215 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
216 struct dentry
*root_dentry
= dentry
->d_sb
->s_root
;
220 ovl_path_real(root_dentry
, &path
);
222 err
= vfs_statfs(&path
, buf
);
224 buf
->f_namelen
= ofs
->namelen
;
225 buf
->f_type
= OVERLAYFS_SUPER_MAGIC
;
234 * Prints the mount options for a given superblock.
235 * Returns zero; does not fail.
237 static int ovl_show_options(struct seq_file
*m
, struct dentry
*dentry
)
239 struct super_block
*sb
= dentry
->d_sb
;
240 struct ovl_fs
*ufs
= sb
->s_fs_info
;
242 seq_show_option(m
, "lowerdir", ufs
->config
.lowerdir
);
243 if (ufs
->config
.upperdir
) {
244 seq_show_option(m
, "upperdir", ufs
->config
.upperdir
);
245 seq_show_option(m
, "workdir", ufs
->config
.workdir
);
247 if (ufs
->config
.default_permissions
)
248 seq_puts(m
, ",default_permissions");
249 if (ufs
->config
.redirect_dir
!= ovl_redirect_dir_def
)
250 seq_printf(m
, ",redirect_dir=%s",
251 ufs
->config
.redirect_dir
? "on" : "off");
255 static int ovl_remount(struct super_block
*sb
, int *flags
, char *data
)
257 struct ovl_fs
*ufs
= sb
->s_fs_info
;
259 if (!(*flags
& MS_RDONLY
) && (!ufs
->upper_mnt
|| !ufs
->workdir
))
265 static const struct super_operations ovl_super_operations
= {
266 .put_super
= ovl_put_super
,
267 .sync_fs
= ovl_sync_fs
,
268 .statfs
= ovl_statfs
,
269 .show_options
= ovl_show_options
,
270 .remount_fs
= ovl_remount
,
271 .drop_inode
= generic_delete_inode
,
278 OPT_DEFAULT_PERMISSIONS
,
280 OPT_REDIRECT_DIR_OFF
,
284 static const match_table_t ovl_tokens
= {
285 {OPT_LOWERDIR
, "lowerdir=%s"},
286 {OPT_UPPERDIR
, "upperdir=%s"},
287 {OPT_WORKDIR
, "workdir=%s"},
288 {OPT_DEFAULT_PERMISSIONS
, "default_permissions"},
289 {OPT_REDIRECT_DIR_ON
, "redirect_dir=on"},
290 {OPT_REDIRECT_DIR_OFF
, "redirect_dir=off"},
294 static char *ovl_next_opt(char **s
)
302 for (p
= sbegin
; *p
; p
++) {
307 } else if (*p
== ',') {
317 static int ovl_parse_opt(char *opt
, struct ovl_config
*config
)
321 while ((p
= ovl_next_opt(&opt
)) != NULL
) {
323 substring_t args
[MAX_OPT_ARGS
];
328 token
= match_token(p
, ovl_tokens
, args
);
331 kfree(config
->upperdir
);
332 config
->upperdir
= match_strdup(&args
[0]);
333 if (!config
->upperdir
)
338 kfree(config
->lowerdir
);
339 config
->lowerdir
= match_strdup(&args
[0]);
340 if (!config
->lowerdir
)
345 kfree(config
->workdir
);
346 config
->workdir
= match_strdup(&args
[0]);
347 if (!config
->workdir
)
351 case OPT_DEFAULT_PERMISSIONS
:
352 config
->default_permissions
= true;
355 case OPT_REDIRECT_DIR_ON
:
356 config
->redirect_dir
= true;
359 case OPT_REDIRECT_DIR_OFF
:
360 config
->redirect_dir
= false;
364 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p
);
369 /* Workdir is useless in non-upper mount */
370 if (!config
->upperdir
&& config
->workdir
) {
371 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
373 kfree(config
->workdir
);
374 config
->workdir
= NULL
;
380 #define OVL_WORKDIR_NAME "work"
382 static struct dentry
*ovl_workdir_create(struct vfsmount
*mnt
,
383 struct dentry
*dentry
)
385 struct inode
*dir
= dentry
->d_inode
;
388 bool retried
= false;
390 err
= mnt_want_write(mnt
);
394 inode_lock_nested(dir
, I_MUTEX_PARENT
);
396 work
= lookup_one_len(OVL_WORKDIR_NAME
, dentry
,
397 strlen(OVL_WORKDIR_NAME
));
400 struct iattr attr
= {
401 .ia_valid
= ATTR_MODE
,
402 .ia_mode
= S_IFDIR
| 0,
411 ovl_workdir_cleanup(dir
, mnt
, work
, 0);
416 err
= ovl_create_real(dir
, work
,
417 &(struct cattr
){.mode
= S_IFDIR
| 0},
423 * Try to remove POSIX ACL xattrs from workdir. We are good if:
425 * a) success (there was a POSIX ACL xattr and was removed)
426 * b) -ENODATA (there was no POSIX ACL xattr)
427 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
429 * There are various other error values that could effectively
430 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
431 * if the xattr name is too long), but the set of filesystems
432 * allowed as upper are limited to "normal" ones, where checking
433 * for the above two errors is sufficient.
435 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_DEFAULT
);
436 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
439 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_ACCESS
);
440 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
443 /* Clear any inherited mode bits */
444 inode_lock(work
->d_inode
);
445 err
= notify_change(work
, &attr
, NULL
);
446 inode_unlock(work
->d_inode
);
462 static void ovl_unescape(char *s
)
475 static int ovl_mount_dir_noesc(const char *name
, struct path
*path
)
480 pr_err("overlayfs: empty lowerdir\n");
483 err
= kern_path(name
, LOOKUP_FOLLOW
, path
);
485 pr_err("overlayfs: failed to resolve '%s': %i\n", name
, err
);
489 if (ovl_dentry_weird(path
->dentry
)) {
490 pr_err("overlayfs: filesystem on '%s' not supported\n", name
);
493 if (!d_is_dir(path
->dentry
)) {
494 pr_err("overlayfs: '%s' not a directory\n", name
);
505 static int ovl_mount_dir(const char *name
, struct path
*path
)
508 char *tmp
= kstrdup(name
, GFP_KERNEL
);
512 err
= ovl_mount_dir_noesc(tmp
, path
);
515 if (ovl_dentry_remote(path
->dentry
)) {
516 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
526 static int ovl_check_namelen(struct path
*path
, struct ovl_fs
*ofs
,
529 struct kstatfs statfs
;
530 int err
= vfs_statfs(path
, &statfs
);
533 pr_err("overlayfs: statfs failed on '%s'\n", name
);
535 ofs
->namelen
= max(ofs
->namelen
, statfs
.f_namelen
);
540 static int ovl_lower_dir(const char *name
, struct path
*path
,
541 struct ovl_fs
*ofs
, int *stack_depth
, bool *remote
)
545 err
= ovl_mount_dir_noesc(name
, path
);
549 err
= ovl_check_namelen(path
, ofs
, name
);
553 *stack_depth
= max(*stack_depth
, path
->mnt
->mnt_sb
->s_stack_depth
);
555 if (ovl_dentry_remote(path
->dentry
))
566 /* Workdir should not be subdir of upperdir and vice versa */
567 static bool ovl_workdir_ok(struct dentry
*workdir
, struct dentry
*upperdir
)
571 if (workdir
!= upperdir
) {
572 ok
= (lock_rename(workdir
, upperdir
) == NULL
);
573 unlock_rename(workdir
, upperdir
);
578 static unsigned int ovl_split_lowerdirs(char *str
)
580 unsigned int ctr
= 1;
583 for (s
= d
= str
;; s
++, d
++) {
586 } else if (*s
== ':') {
598 static int __maybe_unused
599 ovl_posix_acl_xattr_get(const struct xattr_handler
*handler
,
600 struct dentry
*dentry
, struct inode
*inode
,
601 const char *name
, void *buffer
, size_t size
)
603 return ovl_xattr_get(dentry
, handler
->name
, buffer
, size
);
606 static int __maybe_unused
607 ovl_posix_acl_xattr_set(const struct xattr_handler
*handler
,
608 struct dentry
*dentry
, struct inode
*inode
,
609 const char *name
, const void *value
,
610 size_t size
, int flags
)
612 struct dentry
*workdir
= ovl_workdir(dentry
);
613 struct inode
*realinode
= ovl_inode_real(inode
, NULL
);
614 struct posix_acl
*acl
= NULL
;
617 /* Check that everything is OK before copy-up */
619 acl
= posix_acl_from_xattr(&init_user_ns
, value
, size
);
624 if (!IS_POSIXACL(d_inode(workdir
)))
625 goto out_acl_release
;
626 if (!realinode
->i_op
->set_acl
)
627 goto out_acl_release
;
628 if (handler
->flags
== ACL_TYPE_DEFAULT
&& !S_ISDIR(inode
->i_mode
)) {
629 err
= acl
? -EACCES
: 0;
630 goto out_acl_release
;
633 if (!inode_owner_or_capable(inode
))
634 goto out_acl_release
;
636 posix_acl_release(acl
);
639 * Check if sgid bit needs to be cleared (actual setacl operation will
640 * be done with mounter's capabilities and so that won't do it for us).
642 if (unlikely(inode
->i_mode
& S_ISGID
) &&
643 handler
->flags
== ACL_TYPE_ACCESS
&&
644 !in_group_p(inode
->i_gid
) &&
645 !capable_wrt_inode_uidgid(inode
, CAP_FSETID
)) {
646 struct iattr iattr
= { .ia_valid
= ATTR_KILL_SGID
};
648 err
= ovl_setattr(dentry
, &iattr
);
653 err
= ovl_xattr_set(dentry
, handler
->name
, value
, size
, flags
);
655 ovl_copyattr(ovl_inode_real(inode
, NULL
), inode
);
660 posix_acl_release(acl
);
664 static int ovl_own_xattr_get(const struct xattr_handler
*handler
,
665 struct dentry
*dentry
, struct inode
*inode
,
666 const char *name
, void *buffer
, size_t size
)
671 static int ovl_own_xattr_set(const struct xattr_handler
*handler
,
672 struct dentry
*dentry
, struct inode
*inode
,
673 const char *name
, const void *value
,
674 size_t size
, int flags
)
679 static int ovl_other_xattr_get(const struct xattr_handler
*handler
,
680 struct dentry
*dentry
, struct inode
*inode
,
681 const char *name
, void *buffer
, size_t size
)
683 return ovl_xattr_get(dentry
, name
, buffer
, size
);
686 static int ovl_other_xattr_set(const struct xattr_handler
*handler
,
687 struct dentry
*dentry
, struct inode
*inode
,
688 const char *name
, const void *value
,
689 size_t size
, int flags
)
691 return ovl_xattr_set(dentry
, name
, value
, size
, flags
);
694 static const struct xattr_handler __maybe_unused
695 ovl_posix_acl_access_xattr_handler
= {
696 .name
= XATTR_NAME_POSIX_ACL_ACCESS
,
697 .flags
= ACL_TYPE_ACCESS
,
698 .get
= ovl_posix_acl_xattr_get
,
699 .set
= ovl_posix_acl_xattr_set
,
702 static const struct xattr_handler __maybe_unused
703 ovl_posix_acl_default_xattr_handler
= {
704 .name
= XATTR_NAME_POSIX_ACL_DEFAULT
,
705 .flags
= ACL_TYPE_DEFAULT
,
706 .get
= ovl_posix_acl_xattr_get
,
707 .set
= ovl_posix_acl_xattr_set
,
710 static const struct xattr_handler ovl_own_xattr_handler
= {
711 .prefix
= OVL_XATTR_PREFIX
,
712 .get
= ovl_own_xattr_get
,
713 .set
= ovl_own_xattr_set
,
716 static const struct xattr_handler ovl_other_xattr_handler
= {
717 .prefix
= "", /* catch all */
718 .get
= ovl_other_xattr_get
,
719 .set
= ovl_other_xattr_set
,
722 static const struct xattr_handler
*ovl_xattr_handlers
[] = {
723 #ifdef CONFIG_FS_POSIX_ACL
724 &ovl_posix_acl_access_xattr_handler
,
725 &ovl_posix_acl_default_xattr_handler
,
727 &ovl_own_xattr_handler
,
728 &ovl_other_xattr_handler
,
732 static int ovl_fill_super(struct super_block
*sb
, void *data
, int silent
)
734 struct path upperpath
= { };
735 struct path workpath
= { };
736 struct dentry
*root_dentry
;
737 struct inode
*realinode
;
738 struct ovl_entry
*oe
;
740 struct path
*stack
= NULL
;
743 unsigned int numlower
;
744 unsigned int stacklen
= 0;
751 ufs
= kzalloc(sizeof(struct ovl_fs
), GFP_KERNEL
);
755 init_waitqueue_head(&ufs
->copyup_wq
);
756 ufs
->config
.redirect_dir
= ovl_redirect_dir_def
;
757 err
= ovl_parse_opt((char *) data
, &ufs
->config
);
759 goto out_free_config
;
762 if (!ufs
->config
.lowerdir
) {
764 pr_err("overlayfs: missing 'lowerdir'\n");
765 goto out_free_config
;
768 sb
->s_stack_depth
= 0;
769 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
770 if (ufs
->config
.upperdir
) {
771 if (!ufs
->config
.workdir
) {
772 pr_err("overlayfs: missing 'workdir'\n");
773 goto out_free_config
;
776 err
= ovl_mount_dir(ufs
->config
.upperdir
, &upperpath
);
778 goto out_free_config
;
780 /* Upper fs should not be r/o */
781 if (upperpath
.mnt
->mnt_sb
->s_flags
& MS_RDONLY
) {
782 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
784 goto out_put_upperpath
;
787 err
= ovl_check_namelen(&upperpath
, ufs
, ufs
->config
.upperdir
);
789 goto out_put_upperpath
;
791 err
= ovl_mount_dir(ufs
->config
.workdir
, &workpath
);
793 goto out_put_upperpath
;
796 if (upperpath
.mnt
!= workpath
.mnt
) {
797 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
798 goto out_put_workpath
;
800 if (!ovl_workdir_ok(workpath
.dentry
, upperpath
.dentry
)) {
801 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
802 goto out_put_workpath
;
804 sb
->s_stack_depth
= upperpath
.mnt
->mnt_sb
->s_stack_depth
;
807 lowertmp
= kstrdup(ufs
->config
.lowerdir
, GFP_KERNEL
);
809 goto out_put_workpath
;
812 stacklen
= ovl_split_lowerdirs(lowertmp
);
813 if (stacklen
> OVL_MAX_STACK
) {
814 pr_err("overlayfs: too many lower directories, limit is %d\n",
816 goto out_free_lowertmp
;
817 } else if (!ufs
->config
.upperdir
&& stacklen
== 1) {
818 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
819 goto out_free_lowertmp
;
823 stack
= kcalloc(stacklen
, sizeof(struct path
), GFP_KERNEL
);
825 goto out_free_lowertmp
;
829 for (numlower
= 0; numlower
< stacklen
; numlower
++) {
830 err
= ovl_lower_dir(lower
, &stack
[numlower
], ufs
,
831 &sb
->s_stack_depth
, &remote
);
833 goto out_put_lowerpath
;
835 lower
= strchr(lower
, '\0') + 1;
840 if (sb
->s_stack_depth
> FILESYSTEM_MAX_STACK_DEPTH
) {
841 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
842 goto out_put_lowerpath
;
845 if (ufs
->config
.upperdir
) {
846 ufs
->upper_mnt
= clone_private_mount(&upperpath
);
847 err
= PTR_ERR(ufs
->upper_mnt
);
848 if (IS_ERR(ufs
->upper_mnt
)) {
849 pr_err("overlayfs: failed to clone upperpath\n");
850 goto out_put_lowerpath
;
852 /* Don't inherit atime flags */
853 ufs
->upper_mnt
->mnt_flags
&= ~(MNT_NOATIME
| MNT_NODIRATIME
| MNT_RELATIME
);
855 sb
->s_time_gran
= ufs
->upper_mnt
->mnt_sb
->s_time_gran
;
857 ufs
->workdir
= ovl_workdir_create(ufs
->upper_mnt
, workpath
.dentry
);
858 err
= PTR_ERR(ufs
->workdir
);
859 if (IS_ERR(ufs
->workdir
)) {
860 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
861 ufs
->config
.workdir
, OVL_WORKDIR_NAME
, -err
);
862 sb
->s_flags
|= MS_RDONLY
;
867 * Upper should support d_type, else whiteouts are visible.
868 * Given workdir and upper are on same fs, we can do
869 * iterate_dir() on workdir. This check requires successful
870 * creation of workdir in previous step.
875 err
= ovl_check_d_type_supported(&workpath
);
877 goto out_put_workdir
;
880 * We allowed this configuration and don't want to
881 * break users over kernel upgrade. So warn instead
885 pr_warn("overlayfs: upper fs needs to support d_type.\n");
887 /* Check if upper/work fs supports O_TMPFILE */
888 temp
= ovl_do_tmpfile(ufs
->workdir
, S_IFREG
| 0);
889 ufs
->tmpfile
= !IS_ERR(temp
);
893 pr_warn("overlayfs: upper fs does not support tmpfile.\n");
896 * Check if upper/work fs supports trusted.overlay.*
899 err
= ovl_do_setxattr(ufs
->workdir
, OVL_XATTR_OPAQUE
,
903 pr_warn("overlayfs: upper fs does not support xattr.\n");
905 vfs_removexattr(ufs
->workdir
, OVL_XATTR_OPAQUE
);
911 ufs
->lower_mnt
= kcalloc(numlower
, sizeof(struct vfsmount
*), GFP_KERNEL
);
912 if (ufs
->lower_mnt
== NULL
)
913 goto out_put_workdir
;
914 for (i
= 0; i
< numlower
; i
++) {
915 struct vfsmount
*mnt
= clone_private_mount(&stack
[i
]);
919 pr_err("overlayfs: failed to clone lowerpath\n");
920 goto out_put_lower_mnt
;
923 * Make lower_mnt R/O. That way fchmod/fchown on lower file
924 * will fail instead of modifying lower fs.
926 mnt
->mnt_flags
|= MNT_READONLY
| MNT_NOATIME
;
928 ufs
->lower_mnt
[ufs
->numlower
] = mnt
;
931 /* Check if all lower layers are on same sb */
933 ufs
->same_sb
= mnt
->mnt_sb
;
934 else if (ufs
->same_sb
!= mnt
->mnt_sb
)
938 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
940 sb
->s_flags
|= MS_RDONLY
;
941 else if (ufs
->upper_mnt
->mnt_sb
!= ufs
->same_sb
)
945 sb
->s_d_op
= &ovl_reval_dentry_operations
;
947 sb
->s_d_op
= &ovl_dentry_operations
;
949 ufs
->creator_cred
= cred
= prepare_creds();
951 goto out_put_lower_mnt
;
953 /* Never override disk quota limits or use reserved space */
954 cap_lower(cred
->cap_effective
, CAP_SYS_RESOURCE
);
957 oe
= ovl_alloc_entry(numlower
);
961 sb
->s_magic
= OVERLAYFS_SUPER_MAGIC
;
962 sb
->s_op
= &ovl_super_operations
;
963 sb
->s_xattr
= ovl_xattr_handlers
;
965 sb
->s_flags
|= MS_POSIXACL
| MS_NOREMOTELOCK
;
967 root_dentry
= d_make_root(ovl_new_inode(sb
, S_IFDIR
, 0));
971 mntput(upperpath
.mnt
);
972 for (i
= 0; i
< numlower
; i
++)
973 mntput(stack
[i
].mnt
);
977 if (upperpath
.dentry
) {
978 oe
->__upperdentry
= upperpath
.dentry
;
979 oe
->impure
= ovl_is_impuredir(upperpath
.dentry
);
981 for (i
= 0; i
< numlower
; i
++) {
982 oe
->lowerstack
[i
].dentry
= stack
[i
].dentry
;
983 oe
->lowerstack
[i
].mnt
= ufs
->lower_mnt
[i
];
987 root_dentry
->d_fsdata
= oe
;
989 realinode
= d_inode(ovl_dentry_real(root_dentry
));
990 ovl_inode_init(d_inode(root_dentry
), realinode
, !!upperpath
.dentry
);
991 ovl_copyattr(realinode
, d_inode(root_dentry
));
993 sb
->s_root
= root_dentry
;
1000 put_cred(ufs
->creator_cred
);
1002 for (i
= 0; i
< ufs
->numlower
; i
++)
1003 mntput(ufs
->lower_mnt
[i
]);
1004 kfree(ufs
->lower_mnt
);
1007 mntput(ufs
->upper_mnt
);
1009 for (i
= 0; i
< numlower
; i
++)
1010 path_put(&stack
[i
]);
1015 path_put(&workpath
);
1017 path_put(&upperpath
);
1019 kfree(ufs
->config
.lowerdir
);
1020 kfree(ufs
->config
.upperdir
);
1021 kfree(ufs
->config
.workdir
);
1027 static struct dentry
*ovl_mount(struct file_system_type
*fs_type
, int flags
,
1028 const char *dev_name
, void *raw_data
)
1030 return mount_nodev(fs_type
, flags
, raw_data
, ovl_fill_super
);
1033 static struct file_system_type ovl_fs_type
= {
1034 .owner
= THIS_MODULE
,
1037 .kill_sb
= kill_anon_super
,
1039 MODULE_ALIAS_FS("overlay");
1041 static int __init
ovl_init(void)
1043 return register_filesystem(&ovl_fs_type
);
1046 static void __exit
ovl_exit(void)
1048 unregister_filesystem(&ovl_fs_type
);
1051 module_init(ovl_init
);
1052 module_exit(ovl_exit
);