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/pagemap.h>
13 #include <linux/xattr.h>
14 #include <linux/security.h>
15 #include <linux/mount.h>
16 #include <linux/slab.h>
17 #include <linux/parser.h>
18 #include <linux/module.h>
19 #include <linux/pagemap.h>
20 #include <linux/sched.h>
21 #include <linux/statfs.h>
22 #include <linux/seq_file.h>
23 #include "overlayfs.h"
25 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
26 MODULE_DESCRIPTION("Overlay filesystem");
27 MODULE_LICENSE("GPL");
33 bool default_permissions
;
36 /* private information held for overlayfs's superblock */
38 struct vfsmount
*upper_mnt
;
40 struct vfsmount
**lower_mnt
;
41 struct dentry
*workdir
;
43 /* pathnames of lower and upper dirs, for show_options */
44 struct ovl_config config
;
49 /* private information held for every overlayfs dentry */
51 struct dentry
*__upperdentry
;
52 struct ovl_dir_cache
*cache
;
61 struct path lowerstack
[];
64 #define OVL_MAX_STACK 500
66 static struct dentry
*__ovl_dentry_lower(struct ovl_entry
*oe
)
68 return oe
->numlower
? oe
->lowerstack
[0].dentry
: NULL
;
71 enum ovl_path_type
ovl_path_type(struct dentry
*dentry
)
73 struct ovl_entry
*oe
= dentry
->d_fsdata
;
74 enum ovl_path_type type
= 0;
76 if (oe
->__upperdentry
) {
77 type
= __OVL_PATH_UPPER
;
80 * Non-dir dentry can hold lower dentry from previous
81 * location. Its purity depends only on opaque flag.
83 if (oe
->numlower
&& S_ISDIR(dentry
->d_inode
->i_mode
))
84 type
|= __OVL_PATH_MERGE
;
86 type
|= __OVL_PATH_PURE
;
89 type
|= __OVL_PATH_MERGE
;
94 static struct dentry
*ovl_upperdentry_dereference(struct ovl_entry
*oe
)
96 return lockless_dereference(oe
->__upperdentry
);
99 void ovl_path_upper(struct dentry
*dentry
, struct path
*path
)
101 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
102 struct ovl_entry
*oe
= dentry
->d_fsdata
;
104 path
->mnt
= ofs
->upper_mnt
;
105 path
->dentry
= ovl_upperdentry_dereference(oe
);
108 enum ovl_path_type
ovl_path_real(struct dentry
*dentry
, struct path
*path
)
110 enum ovl_path_type type
= ovl_path_type(dentry
);
112 if (!OVL_TYPE_UPPER(type
))
113 ovl_path_lower(dentry
, path
);
115 ovl_path_upper(dentry
, path
);
120 struct dentry
*ovl_dentry_upper(struct dentry
*dentry
)
122 struct ovl_entry
*oe
= dentry
->d_fsdata
;
124 return ovl_upperdentry_dereference(oe
);
127 struct dentry
*ovl_dentry_lower(struct dentry
*dentry
)
129 struct ovl_entry
*oe
= dentry
->d_fsdata
;
131 return __ovl_dentry_lower(oe
);
134 struct dentry
*ovl_dentry_real(struct dentry
*dentry
)
136 struct ovl_entry
*oe
= dentry
->d_fsdata
;
137 struct dentry
*realdentry
;
139 realdentry
= ovl_upperdentry_dereference(oe
);
141 realdentry
= __ovl_dentry_lower(oe
);
146 struct dentry
*ovl_entry_real(struct ovl_entry
*oe
, bool *is_upper
)
148 struct dentry
*realdentry
;
150 realdentry
= ovl_upperdentry_dereference(oe
);
154 realdentry
= __ovl_dentry_lower(oe
);
160 struct vfsmount
*ovl_entry_mnt_real(struct ovl_entry
*oe
, struct inode
*inode
,
164 struct ovl_fs
*ofs
= inode
->i_sb
->s_fs_info
;
166 return ofs
->upper_mnt
;
168 return oe
->numlower
? oe
->lowerstack
[0].mnt
: NULL
;
172 struct ovl_dir_cache
*ovl_dir_cache(struct dentry
*dentry
)
174 struct ovl_entry
*oe
= dentry
->d_fsdata
;
179 bool ovl_is_default_permissions(struct inode
*inode
)
181 struct ovl_fs
*ofs
= inode
->i_sb
->s_fs_info
;
183 return ofs
->config
.default_permissions
;
186 void ovl_set_dir_cache(struct dentry
*dentry
, struct ovl_dir_cache
*cache
)
188 struct ovl_entry
*oe
= dentry
->d_fsdata
;
193 void ovl_path_lower(struct dentry
*dentry
, struct path
*path
)
195 struct ovl_entry
*oe
= dentry
->d_fsdata
;
197 *path
= oe
->numlower
? oe
->lowerstack
[0] : (struct path
) { NULL
, NULL
};
200 int ovl_want_write(struct dentry
*dentry
)
202 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
203 return mnt_want_write(ofs
->upper_mnt
);
206 void ovl_drop_write(struct dentry
*dentry
)
208 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
209 mnt_drop_write(ofs
->upper_mnt
);
212 struct dentry
*ovl_workdir(struct dentry
*dentry
)
214 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
218 bool ovl_dentry_is_opaque(struct dentry
*dentry
)
220 struct ovl_entry
*oe
= dentry
->d_fsdata
;
224 void ovl_dentry_set_opaque(struct dentry
*dentry
, bool opaque
)
226 struct ovl_entry
*oe
= dentry
->d_fsdata
;
230 void ovl_dentry_update(struct dentry
*dentry
, struct dentry
*upperdentry
)
232 struct ovl_entry
*oe
= dentry
->d_fsdata
;
234 WARN_ON(!inode_is_locked(upperdentry
->d_parent
->d_inode
));
235 WARN_ON(oe
->__upperdentry
);
236 BUG_ON(!upperdentry
->d_inode
);
238 * Make sure upperdentry is consistent before making it visible to
239 * ovl_upperdentry_dereference().
242 oe
->__upperdentry
= upperdentry
;
245 void ovl_dentry_version_inc(struct dentry
*dentry
)
247 struct ovl_entry
*oe
= dentry
->d_fsdata
;
249 WARN_ON(!inode_is_locked(dentry
->d_inode
));
253 u64
ovl_dentry_version_get(struct dentry
*dentry
)
255 struct ovl_entry
*oe
= dentry
->d_fsdata
;
257 WARN_ON(!inode_is_locked(dentry
->d_inode
));
261 bool ovl_is_whiteout(struct dentry
*dentry
)
263 struct inode
*inode
= dentry
->d_inode
;
265 return inode
&& IS_WHITEOUT(inode
);
268 static bool ovl_is_opaquedir(struct dentry
*dentry
)
272 struct inode
*inode
= dentry
->d_inode
;
274 if (!S_ISDIR(inode
->i_mode
) || !inode
->i_op
->getxattr
)
277 res
= inode
->i_op
->getxattr(dentry
, inode
, OVL_XATTR_OPAQUE
, &val
, 1);
278 if (res
== 1 && val
== 'y')
284 static void ovl_dentry_release(struct dentry
*dentry
)
286 struct ovl_entry
*oe
= dentry
->d_fsdata
;
291 dput(oe
->__upperdentry
);
292 for (i
= 0; i
< oe
->numlower
; i
++)
293 dput(oe
->lowerstack
[i
].dentry
);
298 static struct dentry
*ovl_d_real(struct dentry
*dentry
, struct inode
*inode
)
302 if (d_is_dir(dentry
)) {
303 if (!inode
|| inode
== d_inode(dentry
))
308 real
= ovl_dentry_upper(dentry
);
309 if (real
&& (!inode
|| inode
== d_inode(real
)))
312 real
= ovl_dentry_lower(dentry
);
316 if (!inode
|| inode
== d_inode(real
))
319 /* Handle recursion */
320 if (real
->d_flags
& DCACHE_OP_REAL
)
321 return real
->d_op
->d_real(real
, inode
);
324 WARN(1, "ovl_d_real(%pd4, %s:%lu\n): real dentry not found\n", dentry
,
325 inode
? inode
->i_sb
->s_id
: "NULL", inode
? inode
->i_ino
: 0);
329 static int ovl_dentry_revalidate(struct dentry
*dentry
, unsigned int flags
)
331 struct ovl_entry
*oe
= dentry
->d_fsdata
;
335 for (i
= 0; i
< oe
->numlower
; i
++) {
336 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
338 if (d
->d_flags
& DCACHE_OP_REVALIDATE
) {
339 ret
= d
->d_op
->d_revalidate(d
, flags
);
343 if (!(flags
& LOOKUP_RCU
))
352 static int ovl_dentry_weak_revalidate(struct dentry
*dentry
, unsigned int flags
)
354 struct ovl_entry
*oe
= dentry
->d_fsdata
;
358 for (i
= 0; i
< oe
->numlower
; i
++) {
359 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
361 if (d
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
) {
362 ret
= d
->d_op
->d_weak_revalidate(d
, flags
);
370 static const struct dentry_operations ovl_dentry_operations
= {
371 .d_release
= ovl_dentry_release
,
372 .d_select_inode
= ovl_d_select_inode
,
373 .d_real
= ovl_d_real
,
376 static const struct dentry_operations ovl_reval_dentry_operations
= {
377 .d_release
= ovl_dentry_release
,
378 .d_select_inode
= ovl_d_select_inode
,
379 .d_real
= ovl_d_real
,
380 .d_revalidate
= ovl_dentry_revalidate
,
381 .d_weak_revalidate
= ovl_dentry_weak_revalidate
,
384 static struct ovl_entry
*ovl_alloc_entry(unsigned int numlower
)
386 size_t size
= offsetof(struct ovl_entry
, lowerstack
[numlower
]);
387 struct ovl_entry
*oe
= kzalloc(size
, GFP_KERNEL
);
390 oe
->numlower
= numlower
;
395 static bool ovl_dentry_remote(struct dentry
*dentry
)
397 return dentry
->d_flags
&
398 (DCACHE_OP_REVALIDATE
| DCACHE_OP_WEAK_REVALIDATE
);
401 static bool ovl_dentry_weird(struct dentry
*dentry
)
403 return dentry
->d_flags
& (DCACHE_NEED_AUTOMOUNT
|
404 DCACHE_MANAGE_TRANSIT
|
409 static inline struct dentry
*ovl_lookup_real(struct dentry
*dir
,
412 struct dentry
*dentry
;
414 dentry
= lookup_hash(name
, dir
);
416 if (IS_ERR(dentry
)) {
417 if (PTR_ERR(dentry
) == -ENOENT
)
419 } else if (!dentry
->d_inode
) {
422 } else if (ovl_dentry_weird(dentry
)) {
424 /* Don't support traversing automounts and other weirdness */
425 dentry
= ERR_PTR(-EREMOTE
);
431 * Returns next layer in stack starting from top.
432 * Returns -1 if this is the last layer.
434 int ovl_path_next(int idx
, struct dentry
*dentry
, struct path
*path
)
436 struct ovl_entry
*oe
= dentry
->d_fsdata
;
440 ovl_path_upper(dentry
, path
);
442 return oe
->numlower
? 1 : -1;
445 BUG_ON(idx
> oe
->numlower
);
446 *path
= oe
->lowerstack
[idx
- 1];
448 return (idx
< oe
->numlower
) ? idx
+ 1 : -1;
451 struct dentry
*ovl_lookup(struct inode
*dir
, struct dentry
*dentry
,
454 struct ovl_entry
*oe
;
455 struct ovl_entry
*poe
= dentry
->d_parent
->d_fsdata
;
456 struct path
*stack
= NULL
;
457 struct dentry
*upperdir
, *upperdentry
= NULL
;
458 unsigned int ctr
= 0;
459 struct inode
*inode
= NULL
;
460 bool upperopaque
= false;
461 struct dentry
*this, *prev
= NULL
;
465 upperdir
= ovl_upperdentry_dereference(poe
);
467 this = ovl_lookup_real(upperdir
, &dentry
->d_name
);
473 if (unlikely(ovl_dentry_remote(this))) {
478 if (ovl_is_whiteout(this)) {
482 } else if (poe
->numlower
&& ovl_is_opaquedir(this)) {
486 upperdentry
= prev
= this;
489 if (!upperopaque
&& poe
->numlower
) {
491 stack
= kcalloc(poe
->numlower
, sizeof(struct path
), GFP_KERNEL
);
496 for (i
= 0; !upperopaque
&& i
< poe
->numlower
; i
++) {
498 struct path lowerpath
= poe
->lowerstack
[i
];
500 this = ovl_lookup_real(lowerpath
.dentry
, &dentry
->d_name
);
504 * If it's positive, then treat ENAMETOOLONG as ENOENT.
506 if (err
== -ENAMETOOLONG
&& (upperdentry
|| ctr
))
512 if (ovl_is_whiteout(this)) {
517 * Only makes sense to check opaque dir if this is not the
520 if (i
< poe
->numlower
- 1 && ovl_is_opaquedir(this))
523 if (prev
&& (!S_ISDIR(prev
->d_inode
->i_mode
) ||
524 !S_ISDIR(this->d_inode
->i_mode
))) {
526 * FIXME: check for upper-opaqueness maybe better done
529 if (prev
== upperdentry
)
535 * If this is a non-directory then stop here.
537 if (!S_ISDIR(this->d_inode
->i_mode
))
540 stack
[ctr
].dentry
= this;
541 stack
[ctr
].mnt
= lowerpath
.mnt
;
548 oe
= ovl_alloc_entry(ctr
);
553 if (upperdentry
|| ctr
) {
554 struct dentry
*realdentry
;
556 realdentry
= upperdentry
? upperdentry
: stack
[0].dentry
;
559 inode
= ovl_new_inode(dentry
->d_sb
, realdentry
->d_inode
->i_mode
,
563 ovl_copyattr(realdentry
->d_inode
, inode
);
566 oe
->opaque
= upperopaque
;
567 oe
->__upperdentry
= upperdentry
;
568 memcpy(oe
->lowerstack
, stack
, sizeof(struct path
) * ctr
);
570 dentry
->d_fsdata
= oe
;
571 d_add(dentry
, inode
);
578 for (i
= 0; i
< ctr
; i
++)
579 dput(stack
[i
].dentry
);
587 struct file
*ovl_path_open(struct path
*path
, int flags
)
589 return dentry_open(path
, flags
, current_cred());
592 static void ovl_put_super(struct super_block
*sb
)
594 struct ovl_fs
*ufs
= sb
->s_fs_info
;
598 mntput(ufs
->upper_mnt
);
599 for (i
= 0; i
< ufs
->numlower
; i
++)
600 mntput(ufs
->lower_mnt
[i
]);
601 kfree(ufs
->lower_mnt
);
603 kfree(ufs
->config
.lowerdir
);
604 kfree(ufs
->config
.upperdir
);
605 kfree(ufs
->config
.workdir
);
611 * @sb: The overlayfs super block
612 * @buf: The struct kstatfs to fill in with stats
614 * Get the filesystem statistics. As writes always target the upper layer
615 * filesystem pass the statfs to the upper filesystem (if it exists)
617 static int ovl_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
619 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
620 struct dentry
*root_dentry
= dentry
->d_sb
->s_root
;
624 ovl_path_real(root_dentry
, &path
);
626 err
= vfs_statfs(&path
, buf
);
628 buf
->f_namelen
= max(buf
->f_namelen
, ofs
->lower_namelen
);
629 buf
->f_type
= OVERLAYFS_SUPER_MAGIC
;
638 * Prints the mount options for a given superblock.
639 * Returns zero; does not fail.
641 static int ovl_show_options(struct seq_file
*m
, struct dentry
*dentry
)
643 struct super_block
*sb
= dentry
->d_sb
;
644 struct ovl_fs
*ufs
= sb
->s_fs_info
;
646 seq_show_option(m
, "lowerdir", ufs
->config
.lowerdir
);
647 if (ufs
->config
.upperdir
) {
648 seq_show_option(m
, "upperdir", ufs
->config
.upperdir
);
649 seq_show_option(m
, "workdir", ufs
->config
.workdir
);
651 if (ufs
->config
.default_permissions
)
652 seq_puts(m
, ",default_permissions");
656 static int ovl_remount(struct super_block
*sb
, int *flags
, char *data
)
658 struct ovl_fs
*ufs
= sb
->s_fs_info
;
660 if (!(*flags
& MS_RDONLY
) && (!ufs
->upper_mnt
|| !ufs
->workdir
))
666 static const struct super_operations ovl_super_operations
= {
667 .put_super
= ovl_put_super
,
668 .statfs
= ovl_statfs
,
669 .show_options
= ovl_show_options
,
670 .remount_fs
= ovl_remount
,
677 OPT_DEFAULT_PERMISSIONS
,
681 static const match_table_t ovl_tokens
= {
682 {OPT_LOWERDIR
, "lowerdir=%s"},
683 {OPT_UPPERDIR
, "upperdir=%s"},
684 {OPT_WORKDIR
, "workdir=%s"},
685 {OPT_DEFAULT_PERMISSIONS
, "default_permissions"},
689 static char *ovl_next_opt(char **s
)
697 for (p
= sbegin
; *p
; p
++) {
702 } else if (*p
== ',') {
712 static int ovl_parse_opt(char *opt
, struct ovl_config
*config
)
716 while ((p
= ovl_next_opt(&opt
)) != NULL
) {
718 substring_t args
[MAX_OPT_ARGS
];
723 token
= match_token(p
, ovl_tokens
, args
);
726 kfree(config
->upperdir
);
727 config
->upperdir
= match_strdup(&args
[0]);
728 if (!config
->upperdir
)
733 kfree(config
->lowerdir
);
734 config
->lowerdir
= match_strdup(&args
[0]);
735 if (!config
->lowerdir
)
740 kfree(config
->workdir
);
741 config
->workdir
= match_strdup(&args
[0]);
742 if (!config
->workdir
)
746 case OPT_DEFAULT_PERMISSIONS
:
747 config
->default_permissions
= true;
751 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p
);
756 /* Workdir is useless in non-upper mount */
757 if (!config
->upperdir
&& config
->workdir
) {
758 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
760 kfree(config
->workdir
);
761 config
->workdir
= NULL
;
767 #define OVL_WORKDIR_NAME "work"
769 static struct dentry
*ovl_workdir_create(struct vfsmount
*mnt
,
770 struct dentry
*dentry
)
772 struct inode
*dir
= dentry
->d_inode
;
775 bool retried
= false;
777 err
= mnt_want_write(mnt
);
781 inode_lock_nested(dir
, I_MUTEX_PARENT
);
783 work
= lookup_one_len(OVL_WORKDIR_NAME
, dentry
,
784 strlen(OVL_WORKDIR_NAME
));
787 struct kstat stat
= {
797 ovl_cleanup(dir
, work
);
802 err
= ovl_create_real(dir
, work
, &stat
, NULL
, NULL
, true);
818 static void ovl_unescape(char *s
)
831 static int ovl_mount_dir_noesc(const char *name
, struct path
*path
)
836 pr_err("overlayfs: empty lowerdir\n");
839 err
= kern_path(name
, LOOKUP_FOLLOW
, path
);
841 pr_err("overlayfs: failed to resolve '%s': %i\n", name
, err
);
845 if (ovl_dentry_weird(path
->dentry
)) {
846 pr_err("overlayfs: filesystem on '%s' not supported\n", name
);
849 if (!S_ISDIR(path
->dentry
->d_inode
->i_mode
)) {
850 pr_err("overlayfs: '%s' not a directory\n", name
);
861 static int ovl_mount_dir(const char *name
, struct path
*path
)
864 char *tmp
= kstrdup(name
, GFP_KERNEL
);
868 err
= ovl_mount_dir_noesc(tmp
, path
);
871 if (ovl_dentry_remote(path
->dentry
)) {
872 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
882 static int ovl_lower_dir(const char *name
, struct path
*path
, long *namelen
,
883 int *stack_depth
, bool *remote
)
886 struct kstatfs statfs
;
888 err
= ovl_mount_dir_noesc(name
, path
);
892 err
= vfs_statfs(path
, &statfs
);
894 pr_err("overlayfs: statfs failed on '%s'\n", name
);
897 *namelen
= max(*namelen
, statfs
.f_namelen
);
898 *stack_depth
= max(*stack_depth
, path
->mnt
->mnt_sb
->s_stack_depth
);
900 if (ovl_dentry_remote(path
->dentry
))
911 /* Workdir should not be subdir of upperdir and vice versa */
912 static bool ovl_workdir_ok(struct dentry
*workdir
, struct dentry
*upperdir
)
916 if (workdir
!= upperdir
) {
917 ok
= (lock_rename(workdir
, upperdir
) == NULL
);
918 unlock_rename(workdir
, upperdir
);
923 static unsigned int ovl_split_lowerdirs(char *str
)
925 unsigned int ctr
= 1;
928 for (s
= d
= str
;; s
++, d
++) {
931 } else if (*s
== ':') {
943 static int ovl_fill_super(struct super_block
*sb
, void *data
, int silent
)
945 struct path upperpath
= { NULL
, NULL
};
946 struct path workpath
= { NULL
, NULL
};
947 struct dentry
*root_dentry
;
948 struct ovl_entry
*oe
;
950 struct path
*stack
= NULL
;
953 unsigned int numlower
;
954 unsigned int stacklen
= 0;
960 ufs
= kzalloc(sizeof(struct ovl_fs
), GFP_KERNEL
);
964 err
= ovl_parse_opt((char *) data
, &ufs
->config
);
966 goto out_free_config
;
969 if (!ufs
->config
.lowerdir
) {
971 pr_err("overlayfs: missing 'lowerdir'\n");
972 goto out_free_config
;
975 sb
->s_stack_depth
= 0;
976 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
977 if (ufs
->config
.upperdir
) {
978 if (!ufs
->config
.workdir
) {
979 pr_err("overlayfs: missing 'workdir'\n");
980 goto out_free_config
;
983 err
= ovl_mount_dir(ufs
->config
.upperdir
, &upperpath
);
985 goto out_free_config
;
987 /* Upper fs should not be r/o */
988 if (upperpath
.mnt
->mnt_sb
->s_flags
& MS_RDONLY
) {
989 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
991 goto out_put_upperpath
;
994 err
= ovl_mount_dir(ufs
->config
.workdir
, &workpath
);
996 goto out_put_upperpath
;
999 if (upperpath
.mnt
!= workpath
.mnt
) {
1000 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
1001 goto out_put_workpath
;
1003 if (!ovl_workdir_ok(workpath
.dentry
, upperpath
.dentry
)) {
1004 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
1005 goto out_put_workpath
;
1007 sb
->s_stack_depth
= upperpath
.mnt
->mnt_sb
->s_stack_depth
;
1010 lowertmp
= kstrdup(ufs
->config
.lowerdir
, GFP_KERNEL
);
1012 goto out_put_workpath
;
1015 stacklen
= ovl_split_lowerdirs(lowertmp
);
1016 if (stacklen
> OVL_MAX_STACK
) {
1017 pr_err("overlayfs: too many lower directries, limit is %d\n",
1019 goto out_free_lowertmp
;
1020 } else if (!ufs
->config
.upperdir
&& stacklen
== 1) {
1021 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
1022 goto out_free_lowertmp
;
1025 stack
= kcalloc(stacklen
, sizeof(struct path
), GFP_KERNEL
);
1027 goto out_free_lowertmp
;
1030 for (numlower
= 0; numlower
< stacklen
; numlower
++) {
1031 err
= ovl_lower_dir(lower
, &stack
[numlower
],
1032 &ufs
->lower_namelen
, &sb
->s_stack_depth
,
1035 goto out_put_lowerpath
;
1037 lower
= strchr(lower
, '\0') + 1;
1041 sb
->s_stack_depth
++;
1042 if (sb
->s_stack_depth
> FILESYSTEM_MAX_STACK_DEPTH
) {
1043 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
1044 goto out_put_lowerpath
;
1047 if (ufs
->config
.upperdir
) {
1048 ufs
->upper_mnt
= clone_private_mount(&upperpath
);
1049 err
= PTR_ERR(ufs
->upper_mnt
);
1050 if (IS_ERR(ufs
->upper_mnt
)) {
1051 pr_err("overlayfs: failed to clone upperpath\n");
1052 goto out_put_lowerpath
;
1055 ufs
->workdir
= ovl_workdir_create(ufs
->upper_mnt
, workpath
.dentry
);
1056 err
= PTR_ERR(ufs
->workdir
);
1057 if (IS_ERR(ufs
->workdir
)) {
1058 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
1059 ufs
->config
.workdir
, OVL_WORKDIR_NAME
, -err
);
1060 sb
->s_flags
|= MS_RDONLY
;
1061 ufs
->workdir
= NULL
;
1065 * Upper should support d_type, else whiteouts are visible.
1066 * Given workdir and upper are on same fs, we can do
1067 * iterate_dir() on workdir.
1069 err
= ovl_check_d_type_supported(&workpath
);
1071 goto out_put_workdir
;
1074 pr_err("overlayfs: upper fs needs to support d_type.\n");
1076 goto out_put_workdir
;
1081 ufs
->lower_mnt
= kcalloc(numlower
, sizeof(struct vfsmount
*), GFP_KERNEL
);
1082 if (ufs
->lower_mnt
== NULL
)
1083 goto out_put_workdir
;
1084 for (i
= 0; i
< numlower
; i
++) {
1085 struct vfsmount
*mnt
= clone_private_mount(&stack
[i
]);
1089 pr_err("overlayfs: failed to clone lowerpath\n");
1090 goto out_put_lower_mnt
;
1093 * Make lower_mnt R/O. That way fchmod/fchown on lower file
1094 * will fail instead of modifying lower fs.
1096 mnt
->mnt_flags
|= MNT_READONLY
;
1098 ufs
->lower_mnt
[ufs
->numlower
] = mnt
;
1102 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1103 if (!ufs
->upper_mnt
)
1104 sb
->s_flags
|= MS_RDONLY
;
1107 sb
->s_d_op
= &ovl_reval_dentry_operations
;
1109 sb
->s_d_op
= &ovl_dentry_operations
;
1112 oe
= ovl_alloc_entry(numlower
);
1114 goto out_put_lower_mnt
;
1116 root_dentry
= d_make_root(ovl_new_inode(sb
, S_IFDIR
, oe
));
1120 mntput(upperpath
.mnt
);
1121 for (i
= 0; i
< numlower
; i
++)
1122 mntput(stack
[i
].mnt
);
1123 path_put(&workpath
);
1126 oe
->__upperdentry
= upperpath
.dentry
;
1127 for (i
= 0; i
< numlower
; i
++) {
1128 oe
->lowerstack
[i
].dentry
= stack
[i
].dentry
;
1129 oe
->lowerstack
[i
].mnt
= ufs
->lower_mnt
[i
];
1133 root_dentry
->d_fsdata
= oe
;
1135 ovl_copyattr(ovl_dentry_real(root_dentry
)->d_inode
,
1136 root_dentry
->d_inode
);
1138 sb
->s_magic
= OVERLAYFS_SUPER_MAGIC
;
1139 sb
->s_op
= &ovl_super_operations
;
1140 sb
->s_root
= root_dentry
;
1141 sb
->s_fs_info
= ufs
;
1148 for (i
= 0; i
< ufs
->numlower
; i
++)
1149 mntput(ufs
->lower_mnt
[i
]);
1150 kfree(ufs
->lower_mnt
);
1153 mntput(ufs
->upper_mnt
);
1155 for (i
= 0; i
< numlower
; i
++)
1156 path_put(&stack
[i
]);
1161 path_put(&workpath
);
1163 path_put(&upperpath
);
1165 kfree(ufs
->config
.lowerdir
);
1166 kfree(ufs
->config
.upperdir
);
1167 kfree(ufs
->config
.workdir
);
1173 static struct dentry
*ovl_mount(struct file_system_type
*fs_type
, int flags
,
1174 const char *dev_name
, void *raw_data
)
1176 return mount_nodev(fs_type
, flags
, raw_data
, ovl_fill_super
);
1179 static struct file_system_type ovl_fs_type
= {
1180 .owner
= THIS_MODULE
,
1183 .kill_sb
= kill_anon_super
,
1185 MODULE_ALIAS_FS("overlay");
1187 static int __init
ovl_init(void)
1189 return register_filesystem(&ovl_fs_type
);
1192 static void __exit
ovl_exit(void)
1194 unregister_filesystem(&ovl_fs_type
);
1197 module_init(ovl_init
);
1198 module_exit(ovl_exit
);