1 // SPDX-License-Identifier: GPL-2.0-only
4 * Copyright (C) 2011 Novell Inc.
7 #include <uapi/linux/magic.h>
9 #include <linux/namei.h>
10 #include <linux/xattr.h>
11 #include <linux/mount.h>
12 #include <linux/parser.h>
13 #include <linux/module.h>
14 #include <linux/statfs.h>
15 #include <linux/seq_file.h>
16 #include <linux/posix_acl_xattr.h>
17 #include <linux/exportfs.h>
18 #include "overlayfs.h"
20 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
21 MODULE_DESCRIPTION("Overlay filesystem");
22 MODULE_LICENSE("GPL");
27 #define OVL_MAX_STACK 500
29 static bool ovl_redirect_dir_def
= IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR
);
30 module_param_named(redirect_dir
, ovl_redirect_dir_def
, bool, 0644);
31 MODULE_PARM_DESC(redirect_dir
,
32 "Default to on or off for the redirect_dir feature");
34 static bool ovl_redirect_always_follow
=
35 IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
);
36 module_param_named(redirect_always_follow
, ovl_redirect_always_follow
,
38 MODULE_PARM_DESC(redirect_always_follow
,
39 "Follow redirects even if redirect_dir feature is turned off");
41 static bool ovl_index_def
= IS_ENABLED(CONFIG_OVERLAY_FS_INDEX
);
42 module_param_named(index
, ovl_index_def
, bool, 0644);
43 MODULE_PARM_DESC(index
,
44 "Default to on or off for the inodes index feature");
46 static bool ovl_nfs_export_def
= IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT
);
47 module_param_named(nfs_export
, ovl_nfs_export_def
, bool, 0644);
48 MODULE_PARM_DESC(nfs_export
,
49 "Default to on or off for the NFS export feature");
51 static bool ovl_xino_auto_def
= IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO
);
52 module_param_named(xino_auto
, ovl_xino_auto_def
, bool, 0644);
53 MODULE_PARM_DESC(xino_auto
,
54 "Auto enable xino feature");
56 static void ovl_entry_stack_free(struct ovl_entry
*oe
)
60 for (i
= 0; i
< oe
->numlower
; i
++)
61 dput(oe
->lowerstack
[i
].dentry
);
64 static bool ovl_metacopy_def
= IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY
);
65 module_param_named(metacopy
, ovl_metacopy_def
, bool, 0644);
66 MODULE_PARM_DESC(metacopy
,
67 "Default to on or off for the metadata only copy up feature");
69 static void ovl_dentry_release(struct dentry
*dentry
)
71 struct ovl_entry
*oe
= dentry
->d_fsdata
;
74 ovl_entry_stack_free(oe
);
79 static struct dentry
*ovl_d_real(struct dentry
*dentry
,
80 const struct inode
*inode
)
84 /* It's an overlay file */
85 if (inode
&& d_inode(dentry
) == inode
)
88 if (!d_is_reg(dentry
)) {
89 if (!inode
|| inode
== d_inode(dentry
))
94 real
= ovl_dentry_upper(dentry
);
95 if (real
&& (inode
== d_inode(real
)))
98 if (real
&& !inode
&& ovl_has_upperdata(d_inode(dentry
)))
101 real
= ovl_dentry_lowerdata(dentry
);
105 /* Handle recursion */
106 real
= d_real(real
, inode
);
108 if (!inode
|| inode
== d_inode(real
))
111 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry
,
112 inode
? inode
->i_sb
->s_id
: "NULL", inode
? inode
->i_ino
: 0);
116 static int ovl_revalidate_real(struct dentry
*d
, unsigned int flags
, bool weak
)
121 if (d
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)
122 ret
= d
->d_op
->d_weak_revalidate(d
, flags
);
123 } else if (d
->d_flags
& DCACHE_OP_REVALIDATE
) {
124 ret
= d
->d_op
->d_revalidate(d
, flags
);
126 if (!(flags
& LOOKUP_RCU
))
134 static int ovl_dentry_revalidate_common(struct dentry
*dentry
,
135 unsigned int flags
, bool weak
)
137 struct ovl_entry
*oe
= dentry
->d_fsdata
;
138 struct dentry
*upper
;
142 upper
= ovl_dentry_upper(dentry
);
144 ret
= ovl_revalidate_real(upper
, flags
, weak
);
146 for (i
= 0; ret
> 0 && i
< oe
->numlower
; i
++) {
147 ret
= ovl_revalidate_real(oe
->lowerstack
[i
].dentry
, flags
,
153 static int ovl_dentry_revalidate(struct dentry
*dentry
, unsigned int flags
)
155 return ovl_dentry_revalidate_common(dentry
, flags
, false);
158 static int ovl_dentry_weak_revalidate(struct dentry
*dentry
, unsigned int flags
)
160 return ovl_dentry_revalidate_common(dentry
, flags
, true);
163 static const struct dentry_operations ovl_dentry_operations
= {
164 .d_release
= ovl_dentry_release
,
165 .d_real
= ovl_d_real
,
166 .d_revalidate
= ovl_dentry_revalidate
,
167 .d_weak_revalidate
= ovl_dentry_weak_revalidate
,
170 static struct kmem_cache
*ovl_inode_cachep
;
172 static struct inode
*ovl_alloc_inode(struct super_block
*sb
)
174 struct ovl_inode
*oi
= kmem_cache_alloc(ovl_inode_cachep
, GFP_KERNEL
);
183 oi
->__upperdentry
= NULL
;
185 oi
->lowerdata
= NULL
;
186 mutex_init(&oi
->lock
);
188 return &oi
->vfs_inode
;
191 static void ovl_free_inode(struct inode
*inode
)
193 struct ovl_inode
*oi
= OVL_I(inode
);
196 mutex_destroy(&oi
->lock
);
197 kmem_cache_free(ovl_inode_cachep
, oi
);
200 static void ovl_destroy_inode(struct inode
*inode
)
202 struct ovl_inode
*oi
= OVL_I(inode
);
204 dput(oi
->__upperdentry
);
206 if (S_ISDIR(inode
->i_mode
))
207 ovl_dir_cache_free(inode
);
212 static void ovl_free_fs(struct ovl_fs
*ofs
)
214 struct vfsmount
**mounts
;
217 iput(ofs
->workbasedir_trap
);
218 iput(ofs
->indexdir_trap
);
219 iput(ofs
->workdir_trap
);
223 if (ofs
->workdir_locked
)
224 ovl_inuse_unlock(ofs
->workbasedir
);
225 dput(ofs
->workbasedir
);
226 if (ofs
->upperdir_locked
)
227 ovl_inuse_unlock(ovl_upper_mnt(ofs
)->mnt_root
);
229 /* Hack! Reuse ofs->layers as a vfsmount array before freeing it */
230 mounts
= (struct vfsmount
**) ofs
->layers
;
231 for (i
= 0; i
< ofs
->numlayer
; i
++) {
232 iput(ofs
->layers
[i
].trap
);
233 mounts
[i
] = ofs
->layers
[i
].mnt
;
235 kern_unmount_array(mounts
, ofs
->numlayer
);
237 for (i
= 0; i
< ofs
->numfs
; i
++)
238 free_anon_bdev(ofs
->fs
[i
].pseudo_dev
);
241 kfree(ofs
->config
.lowerdir
);
242 kfree(ofs
->config
.upperdir
);
243 kfree(ofs
->config
.workdir
);
244 kfree(ofs
->config
.redirect_mode
);
245 if (ofs
->creator_cred
)
246 put_cred(ofs
->creator_cred
);
250 static void ovl_put_super(struct super_block
*sb
)
252 struct ovl_fs
*ofs
= sb
->s_fs_info
;
257 /* Sync real dirty inodes in upper filesystem (if it exists) */
258 static int ovl_sync_fs(struct super_block
*sb
, int wait
)
260 struct ovl_fs
*ofs
= sb
->s_fs_info
;
261 struct super_block
*upper_sb
;
264 if (!ovl_upper_mnt(ofs
))
268 * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC).
269 * All the super blocks will be iterated, including upper_sb.
271 * If this is a syncfs(2) call, then we do need to call
272 * sync_filesystem() on upper_sb, but enough if we do it when being
273 * called with wait == 1.
278 upper_sb
= ovl_upper_mnt(ofs
)->mnt_sb
;
280 down_read(&upper_sb
->s_umount
);
281 ret
= sync_filesystem(upper_sb
);
282 up_read(&upper_sb
->s_umount
);
289 * @sb: The overlayfs super block
290 * @buf: The struct kstatfs to fill in with stats
292 * Get the filesystem statistics. As writes always target the upper layer
293 * filesystem pass the statfs to the upper filesystem (if it exists)
295 static int ovl_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
297 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
298 struct dentry
*root_dentry
= dentry
->d_sb
->s_root
;
302 ovl_path_real(root_dentry
, &path
);
304 err
= vfs_statfs(&path
, buf
);
306 buf
->f_namelen
= ofs
->namelen
;
307 buf
->f_type
= OVERLAYFS_SUPER_MAGIC
;
313 /* Will this overlay be forced to mount/remount ro? */
314 static bool ovl_force_readonly(struct ovl_fs
*ofs
)
316 return (!ovl_upper_mnt(ofs
) || !ofs
->workdir
);
319 static const char *ovl_redirect_mode_def(void)
321 return ovl_redirect_dir_def
? "on" : "off";
324 static const char * const ovl_xino_str
[] = {
330 static inline int ovl_xino_def(void)
332 return ovl_xino_auto_def
? OVL_XINO_AUTO
: OVL_XINO_OFF
;
338 * Prints the mount options for a given superblock.
339 * Returns zero; does not fail.
341 static int ovl_show_options(struct seq_file
*m
, struct dentry
*dentry
)
343 struct super_block
*sb
= dentry
->d_sb
;
344 struct ovl_fs
*ofs
= sb
->s_fs_info
;
346 seq_show_option(m
, "lowerdir", ofs
->config
.lowerdir
);
347 if (ofs
->config
.upperdir
) {
348 seq_show_option(m
, "upperdir", ofs
->config
.upperdir
);
349 seq_show_option(m
, "workdir", ofs
->config
.workdir
);
351 if (ofs
->config
.default_permissions
)
352 seq_puts(m
, ",default_permissions");
353 if (strcmp(ofs
->config
.redirect_mode
, ovl_redirect_mode_def()) != 0)
354 seq_printf(m
, ",redirect_dir=%s", ofs
->config
.redirect_mode
);
355 if (ofs
->config
.index
!= ovl_index_def
)
356 seq_printf(m
, ",index=%s", ofs
->config
.index
? "on" : "off");
357 if (ofs
->config
.nfs_export
!= ovl_nfs_export_def
)
358 seq_printf(m
, ",nfs_export=%s", ofs
->config
.nfs_export
?
360 if (ofs
->config
.xino
!= ovl_xino_def() && !ovl_same_fs(sb
))
361 seq_printf(m
, ",xino=%s", ovl_xino_str
[ofs
->config
.xino
]);
362 if (ofs
->config
.metacopy
!= ovl_metacopy_def
)
363 seq_printf(m
, ",metacopy=%s",
364 ofs
->config
.metacopy
? "on" : "off");
368 static int ovl_remount(struct super_block
*sb
, int *flags
, char *data
)
370 struct ovl_fs
*ofs
= sb
->s_fs_info
;
371 struct super_block
*upper_sb
;
374 if (!(*flags
& SB_RDONLY
) && ovl_force_readonly(ofs
))
377 if (*flags
& SB_RDONLY
&& !sb_rdonly(sb
)) {
378 upper_sb
= ovl_upper_mnt(ofs
)->mnt_sb
;
379 down_read(&upper_sb
->s_umount
);
380 ret
= sync_filesystem(upper_sb
);
381 up_read(&upper_sb
->s_umount
);
387 static const struct super_operations ovl_super_operations
= {
388 .alloc_inode
= ovl_alloc_inode
,
389 .free_inode
= ovl_free_inode
,
390 .destroy_inode
= ovl_destroy_inode
,
391 .drop_inode
= generic_delete_inode
,
392 .put_super
= ovl_put_super
,
393 .sync_fs
= ovl_sync_fs
,
394 .statfs
= ovl_statfs
,
395 .show_options
= ovl_show_options
,
396 .remount_fs
= ovl_remount
,
403 OPT_DEFAULT_PERMISSIONS
,
417 static const match_table_t ovl_tokens
= {
418 {OPT_LOWERDIR
, "lowerdir=%s"},
419 {OPT_UPPERDIR
, "upperdir=%s"},
420 {OPT_WORKDIR
, "workdir=%s"},
421 {OPT_DEFAULT_PERMISSIONS
, "default_permissions"},
422 {OPT_REDIRECT_DIR
, "redirect_dir=%s"},
423 {OPT_INDEX_ON
, "index=on"},
424 {OPT_INDEX_OFF
, "index=off"},
425 {OPT_NFS_EXPORT_ON
, "nfs_export=on"},
426 {OPT_NFS_EXPORT_OFF
, "nfs_export=off"},
427 {OPT_XINO_ON
, "xino=on"},
428 {OPT_XINO_OFF
, "xino=off"},
429 {OPT_XINO_AUTO
, "xino=auto"},
430 {OPT_METACOPY_ON
, "metacopy=on"},
431 {OPT_METACOPY_OFF
, "metacopy=off"},
435 static char *ovl_next_opt(char **s
)
443 for (p
= sbegin
; *p
; p
++) {
448 } else if (*p
== ',') {
458 static int ovl_parse_redirect_mode(struct ovl_config
*config
, const char *mode
)
460 if (strcmp(mode
, "on") == 0) {
461 config
->redirect_dir
= true;
463 * Does not make sense to have redirect creation without
464 * redirect following.
466 config
->redirect_follow
= true;
467 } else if (strcmp(mode
, "follow") == 0) {
468 config
->redirect_follow
= true;
469 } else if (strcmp(mode
, "off") == 0) {
470 if (ovl_redirect_always_follow
)
471 config
->redirect_follow
= true;
472 } else if (strcmp(mode
, "nofollow") != 0) {
473 pr_err("bad mount option \"redirect_dir=%s\"\n",
481 static int ovl_parse_opt(char *opt
, struct ovl_config
*config
)
485 bool metacopy_opt
= false, redirect_opt
= false;
486 bool nfs_export_opt
= false, index_opt
= false;
488 config
->redirect_mode
= kstrdup(ovl_redirect_mode_def(), GFP_KERNEL
);
489 if (!config
->redirect_mode
)
492 while ((p
= ovl_next_opt(&opt
)) != NULL
) {
494 substring_t args
[MAX_OPT_ARGS
];
499 token
= match_token(p
, ovl_tokens
, args
);
502 kfree(config
->upperdir
);
503 config
->upperdir
= match_strdup(&args
[0]);
504 if (!config
->upperdir
)
509 kfree(config
->lowerdir
);
510 config
->lowerdir
= match_strdup(&args
[0]);
511 if (!config
->lowerdir
)
516 kfree(config
->workdir
);
517 config
->workdir
= match_strdup(&args
[0]);
518 if (!config
->workdir
)
522 case OPT_DEFAULT_PERMISSIONS
:
523 config
->default_permissions
= true;
526 case OPT_REDIRECT_DIR
:
527 kfree(config
->redirect_mode
);
528 config
->redirect_mode
= match_strdup(&args
[0]);
529 if (!config
->redirect_mode
)
535 config
->index
= true;
540 config
->index
= false;
544 case OPT_NFS_EXPORT_ON
:
545 config
->nfs_export
= true;
546 nfs_export_opt
= true;
549 case OPT_NFS_EXPORT_OFF
:
550 config
->nfs_export
= false;
551 nfs_export_opt
= true;
555 config
->xino
= OVL_XINO_ON
;
559 config
->xino
= OVL_XINO_OFF
;
563 config
->xino
= OVL_XINO_AUTO
;
566 case OPT_METACOPY_ON
:
567 config
->metacopy
= true;
571 case OPT_METACOPY_OFF
:
572 config
->metacopy
= false;
577 pr_err("unrecognized mount option \"%s\" or missing value\n",
583 /* Workdir/index are useless in non-upper mount */
584 if (!config
->upperdir
) {
585 if (config
->workdir
) {
586 pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
588 kfree(config
->workdir
);
589 config
->workdir
= NULL
;
591 if (config
->index
&& index_opt
) {
592 pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n");
595 config
->index
= false;
598 err
= ovl_parse_redirect_mode(config
, config
->redirect_mode
);
603 * This is to make the logic below simpler. It doesn't make any other
604 * difference, since config->redirect_dir is only used for upper.
606 if (!config
->upperdir
&& config
->redirect_follow
)
607 config
->redirect_dir
= true;
609 /* Resolve metacopy -> redirect_dir dependency */
610 if (config
->metacopy
&& !config
->redirect_dir
) {
611 if (metacopy_opt
&& redirect_opt
) {
612 pr_err("conflicting options: metacopy=on,redirect_dir=%s\n",
613 config
->redirect_mode
);
618 * There was an explicit redirect_dir=... that resulted
621 pr_info("disabling metacopy due to redirect_dir=%s\n",
622 config
->redirect_mode
);
623 config
->metacopy
= false;
625 /* Automatically enable redirect otherwise. */
626 config
->redirect_follow
= config
->redirect_dir
= true;
630 /* Resolve nfs_export -> index dependency */
631 if (config
->nfs_export
&& !config
->index
) {
632 if (!config
->upperdir
&& config
->redirect_follow
) {
633 pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
634 config
->nfs_export
= false;
635 } else if (nfs_export_opt
&& index_opt
) {
636 pr_err("conflicting options: nfs_export=on,index=off\n");
638 } else if (index_opt
) {
640 * There was an explicit index=off that resulted
643 pr_info("disabling nfs_export due to index=off\n");
644 config
->nfs_export
= false;
646 /* Automatically enable index otherwise. */
647 config
->index
= true;
651 /* Resolve nfs_export -> !metacopy dependency */
652 if (config
->nfs_export
&& config
->metacopy
) {
653 if (nfs_export_opt
&& metacopy_opt
) {
654 pr_err("conflicting options: nfs_export=on,metacopy=on\n");
659 * There was an explicit metacopy=on that resulted
662 pr_info("disabling nfs_export due to metacopy=on\n");
663 config
->nfs_export
= false;
666 * There was an explicit nfs_export=on that resulted
669 pr_info("disabling metacopy due to nfs_export=on\n");
670 config
->metacopy
= false;
677 #define OVL_WORKDIR_NAME "work"
678 #define OVL_INDEXDIR_NAME "index"
680 static struct dentry
*ovl_workdir_create(struct ovl_fs
*ofs
,
681 const char *name
, bool persist
)
683 struct inode
*dir
= ofs
->workbasedir
->d_inode
;
684 struct vfsmount
*mnt
= ovl_upper_mnt(ofs
);
687 bool retried
= false;
689 inode_lock_nested(dir
, I_MUTEX_PARENT
);
691 work
= lookup_one_len(name
, ofs
->workbasedir
, strlen(name
));
694 struct iattr attr
= {
695 .ia_valid
= ATTR_MODE
,
696 .ia_mode
= S_IFDIR
| 0,
708 ovl_workdir_cleanup(dir
, mnt
, work
, 0);
713 work
= ovl_create_real(dir
, work
, OVL_CATTR(attr
.ia_mode
));
719 * Try to remove POSIX ACL xattrs from workdir. We are good if:
721 * a) success (there was a POSIX ACL xattr and was removed)
722 * b) -ENODATA (there was no POSIX ACL xattr)
723 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
725 * There are various other error values that could effectively
726 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
727 * if the xattr name is too long), but the set of filesystems
728 * allowed as upper are limited to "normal" ones, where checking
729 * for the above two errors is sufficient.
731 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_DEFAULT
);
732 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
735 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_ACCESS
);
736 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
739 /* Clear any inherited mode bits */
740 inode_lock(work
->d_inode
);
741 err
= notify_change(work
, &attr
, NULL
);
742 inode_unlock(work
->d_inode
);
756 pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n",
757 ofs
->config
.workdir
, name
, -err
);
762 static void ovl_unescape(char *s
)
775 static int ovl_mount_dir_noesc(const char *name
, struct path
*path
)
780 pr_err("empty lowerdir\n");
783 err
= kern_path(name
, LOOKUP_FOLLOW
, path
);
785 pr_err("failed to resolve '%s': %i\n", name
, err
);
789 if (ovl_dentry_weird(path
->dentry
)) {
790 pr_err("filesystem on '%s' not supported\n", name
);
793 if (!d_is_dir(path
->dentry
)) {
794 pr_err("'%s' not a directory\n", name
);
805 static int ovl_mount_dir(const char *name
, struct path
*path
)
808 char *tmp
= kstrdup(name
, GFP_KERNEL
);
812 err
= ovl_mount_dir_noesc(tmp
, path
);
814 if (!err
&& path
->dentry
->d_flags
& DCACHE_OP_REAL
) {
815 pr_err("filesystem on '%s' not supported as upperdir\n",
825 static int ovl_check_namelen(struct path
*path
, struct ovl_fs
*ofs
,
828 struct kstatfs statfs
;
829 int err
= vfs_statfs(path
, &statfs
);
832 pr_err("statfs failed on '%s'\n", name
);
834 ofs
->namelen
= max(ofs
->namelen
, statfs
.f_namelen
);
839 static int ovl_lower_dir(const char *name
, struct path
*path
,
840 struct ovl_fs
*ofs
, int *stack_depth
)
845 err
= ovl_mount_dir_noesc(name
, path
);
849 err
= ovl_check_namelen(path
, ofs
, name
);
853 *stack_depth
= max(*stack_depth
, path
->mnt
->mnt_sb
->s_stack_depth
);
856 * The inodes index feature and NFS export need to encode and decode
857 * file handles, so they require that all layers support them.
859 fh_type
= ovl_can_decode_fh(path
->dentry
->d_sb
);
860 if ((ofs
->config
.nfs_export
||
861 (ofs
->config
.index
&& ofs
->config
.upperdir
)) && !fh_type
) {
862 ofs
->config
.index
= false;
863 ofs
->config
.nfs_export
= false;
864 pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
868 /* Check if lower fs has 32bit inode numbers */
869 if (fh_type
!= FILEID_INO32_GEN
)
875 /* Workdir should not be subdir of upperdir and vice versa */
876 static bool ovl_workdir_ok(struct dentry
*workdir
, struct dentry
*upperdir
)
880 if (workdir
!= upperdir
) {
881 ok
= (lock_rename(workdir
, upperdir
) == NULL
);
882 unlock_rename(workdir
, upperdir
);
887 static unsigned int ovl_split_lowerdirs(char *str
)
889 unsigned int ctr
= 1;
892 for (s
= d
= str
;; s
++, d
++) {
895 } else if (*s
== ':') {
907 static int __maybe_unused
908 ovl_posix_acl_xattr_get(const struct xattr_handler
*handler
,
909 struct dentry
*dentry
, struct inode
*inode
,
910 const char *name
, void *buffer
, size_t size
)
912 return ovl_xattr_get(dentry
, inode
, handler
->name
, buffer
, size
);
915 static int __maybe_unused
916 ovl_posix_acl_xattr_set(const struct xattr_handler
*handler
,
917 struct dentry
*dentry
, struct inode
*inode
,
918 const char *name
, const void *value
,
919 size_t size
, int flags
)
921 struct dentry
*workdir
= ovl_workdir(dentry
);
922 struct inode
*realinode
= ovl_inode_real(inode
);
923 struct posix_acl
*acl
= NULL
;
926 /* Check that everything is OK before copy-up */
928 acl
= posix_acl_from_xattr(&init_user_ns
, value
, size
);
933 if (!IS_POSIXACL(d_inode(workdir
)))
934 goto out_acl_release
;
935 if (!realinode
->i_op
->set_acl
)
936 goto out_acl_release
;
937 if (handler
->flags
== ACL_TYPE_DEFAULT
&& !S_ISDIR(inode
->i_mode
)) {
938 err
= acl
? -EACCES
: 0;
939 goto out_acl_release
;
942 if (!inode_owner_or_capable(inode
))
943 goto out_acl_release
;
945 posix_acl_release(acl
);
948 * Check if sgid bit needs to be cleared (actual setacl operation will
949 * be done with mounter's capabilities and so that won't do it for us).
951 if (unlikely(inode
->i_mode
& S_ISGID
) &&
952 handler
->flags
== ACL_TYPE_ACCESS
&&
953 !in_group_p(inode
->i_gid
) &&
954 !capable_wrt_inode_uidgid(inode
, CAP_FSETID
)) {
955 struct iattr iattr
= { .ia_valid
= ATTR_KILL_SGID
};
957 err
= ovl_setattr(dentry
, &iattr
);
962 err
= ovl_xattr_set(dentry
, inode
, handler
->name
, value
, size
, flags
);
964 ovl_copyattr(ovl_inode_real(inode
), inode
);
969 posix_acl_release(acl
);
973 static int ovl_own_xattr_get(const struct xattr_handler
*handler
,
974 struct dentry
*dentry
, struct inode
*inode
,
975 const char *name
, void *buffer
, size_t size
)
980 static int ovl_own_xattr_set(const struct xattr_handler
*handler
,
981 struct dentry
*dentry
, struct inode
*inode
,
982 const char *name
, const void *value
,
983 size_t size
, int flags
)
988 static int ovl_other_xattr_get(const struct xattr_handler
*handler
,
989 struct dentry
*dentry
, struct inode
*inode
,
990 const char *name
, void *buffer
, size_t size
)
992 return ovl_xattr_get(dentry
, inode
, name
, buffer
, size
);
995 static int ovl_other_xattr_set(const struct xattr_handler
*handler
,
996 struct dentry
*dentry
, struct inode
*inode
,
997 const char *name
, const void *value
,
998 size_t size
, int flags
)
1000 return ovl_xattr_set(dentry
, inode
, name
, value
, size
, flags
);
1003 static const struct xattr_handler __maybe_unused
1004 ovl_posix_acl_access_xattr_handler
= {
1005 .name
= XATTR_NAME_POSIX_ACL_ACCESS
,
1006 .flags
= ACL_TYPE_ACCESS
,
1007 .get
= ovl_posix_acl_xattr_get
,
1008 .set
= ovl_posix_acl_xattr_set
,
1011 static const struct xattr_handler __maybe_unused
1012 ovl_posix_acl_default_xattr_handler
= {
1013 .name
= XATTR_NAME_POSIX_ACL_DEFAULT
,
1014 .flags
= ACL_TYPE_DEFAULT
,
1015 .get
= ovl_posix_acl_xattr_get
,
1016 .set
= ovl_posix_acl_xattr_set
,
1019 static const struct xattr_handler ovl_own_xattr_handler
= {
1020 .prefix
= OVL_XATTR_PREFIX
,
1021 .get
= ovl_own_xattr_get
,
1022 .set
= ovl_own_xattr_set
,
1025 static const struct xattr_handler ovl_other_xattr_handler
= {
1026 .prefix
= "", /* catch all */
1027 .get
= ovl_other_xattr_get
,
1028 .set
= ovl_other_xattr_set
,
1031 static const struct xattr_handler
*ovl_xattr_handlers
[] = {
1032 #ifdef CONFIG_FS_POSIX_ACL
1033 &ovl_posix_acl_access_xattr_handler
,
1034 &ovl_posix_acl_default_xattr_handler
,
1036 &ovl_own_xattr_handler
,
1037 &ovl_other_xattr_handler
,
1041 static int ovl_setup_trap(struct super_block
*sb
, struct dentry
*dir
,
1042 struct inode
**ptrap
, const char *name
)
1047 trap
= ovl_get_trap_inode(sb
, dir
);
1048 err
= PTR_ERR_OR_ZERO(trap
);
1051 pr_err("conflicting %s path\n", name
);
1060 * Determine how we treat concurrent use of upperdir/workdir based on the
1061 * index feature. This is papering over mount leaks of container runtimes,
1062 * for example, an old overlay mount is leaked and now its upperdir is
1063 * attempted to be used as a lower layer in a new overlay mount.
1065 static int ovl_report_in_use(struct ovl_fs
*ofs
, const char *name
)
1067 if (ofs
->config
.index
) {
1068 pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n",
1072 pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n",
1078 static int ovl_get_upper(struct super_block
*sb
, struct ovl_fs
*ofs
,
1079 struct ovl_layer
*upper_layer
, struct path
*upperpath
)
1081 struct vfsmount
*upper_mnt
;
1084 err
= ovl_mount_dir(ofs
->config
.upperdir
, upperpath
);
1088 /* Upper fs should not be r/o */
1089 if (sb_rdonly(upperpath
->mnt
->mnt_sb
)) {
1090 pr_err("upper fs is r/o, try multi-lower layers mount\n");
1095 err
= ovl_check_namelen(upperpath
, ofs
, ofs
->config
.upperdir
);
1099 err
= ovl_setup_trap(sb
, upperpath
->dentry
, &upper_layer
->trap
,
1104 upper_mnt
= clone_private_mount(upperpath
);
1105 err
= PTR_ERR(upper_mnt
);
1106 if (IS_ERR(upper_mnt
)) {
1107 pr_err("failed to clone upperpath\n");
1111 /* Don't inherit atime flags */
1112 upper_mnt
->mnt_flags
&= ~(MNT_NOATIME
| MNT_NODIRATIME
| MNT_RELATIME
);
1113 upper_layer
->mnt
= upper_mnt
;
1114 upper_layer
->idx
= 0;
1115 upper_layer
->fsid
= 0;
1118 * Inherit SB_NOSEC flag from upperdir.
1120 * This optimization changes behavior when a security related attribute
1121 * (suid/sgid/security.*) is changed on an underlying layer. This is
1122 * okay because we don't yet have guarantees in that case, but it will
1123 * need careful treatment once we want to honour changes to underlying
1126 if (upper_mnt
->mnt_sb
->s_flags
& SB_NOSEC
)
1127 sb
->s_flags
|= SB_NOSEC
;
1129 if (ovl_inuse_trylock(ovl_upper_mnt(ofs
)->mnt_root
)) {
1130 ofs
->upperdir_locked
= true;
1132 err
= ovl_report_in_use(ofs
, "upperdir");
1143 * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and
1144 * negative values if error is encountered.
1146 static int ovl_check_rename_whiteout(struct dentry
*workdir
)
1148 struct inode
*dir
= d_inode(workdir
);
1149 struct dentry
*temp
;
1150 struct dentry
*dest
;
1151 struct dentry
*whiteout
;
1152 struct name_snapshot name
;
1155 inode_lock_nested(dir
, I_MUTEX_PARENT
);
1157 temp
= ovl_create_temp(workdir
, OVL_CATTR(S_IFREG
| 0));
1158 err
= PTR_ERR(temp
);
1162 dest
= ovl_lookup_temp(workdir
);
1163 err
= PTR_ERR(dest
);
1169 /* Name is inline and stable - using snapshot as a copy helper */
1170 take_dentry_name_snapshot(&name
, temp
);
1171 err
= ovl_do_rename(dir
, temp
, dir
, dest
, RENAME_WHITEOUT
);
1178 whiteout
= lookup_one_len(name
.name
.name
, workdir
, name
.name
.len
);
1179 err
= PTR_ERR(whiteout
);
1180 if (IS_ERR(whiteout
))
1183 err
= ovl_is_whiteout(whiteout
);
1185 /* Best effort cleanup of whiteout and temp file */
1187 ovl_cleanup(dir
, whiteout
);
1191 ovl_cleanup(dir
, temp
);
1192 release_dentry_name_snapshot(&name
);
1202 static int ovl_make_workdir(struct super_block
*sb
, struct ovl_fs
*ofs
,
1203 struct path
*workpath
)
1205 struct vfsmount
*mnt
= ovl_upper_mnt(ofs
);
1206 struct dentry
*temp
;
1207 bool rename_whiteout
;
1212 err
= mnt_want_write(mnt
);
1216 ofs
->workdir
= ovl_workdir_create(ofs
, OVL_WORKDIR_NAME
, false);
1220 err
= ovl_setup_trap(sb
, ofs
->workdir
, &ofs
->workdir_trap
, "workdir");
1225 * Upper should support d_type, else whiteouts are visible. Given
1226 * workdir and upper are on same fs, we can do iterate_dir() on
1227 * workdir. This check requires successful creation of workdir in
1230 err
= ovl_check_d_type_supported(workpath
);
1236 pr_warn("upper fs needs to support d_type.\n");
1238 /* Check if upper/work fs supports O_TMPFILE */
1239 temp
= ovl_do_tmpfile(ofs
->workdir
, S_IFREG
| 0);
1240 ofs
->tmpfile
= !IS_ERR(temp
);
1244 pr_warn("upper fs does not support tmpfile.\n");
1247 /* Check if upper/work fs supports RENAME_WHITEOUT */
1248 err
= ovl_check_rename_whiteout(ofs
->workdir
);
1252 rename_whiteout
= err
;
1253 if (!rename_whiteout
)
1254 pr_warn("upper fs does not support RENAME_WHITEOUT.\n");
1257 * Check if upper/work fs supports trusted.overlay.* xattr
1259 err
= ovl_do_setxattr(ofs
->workdir
, OVL_XATTR_OPAQUE
, "0", 1, 0);
1261 ofs
->noxattr
= true;
1262 ofs
->config
.index
= false;
1263 ofs
->config
.metacopy
= false;
1264 pr_warn("upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
1267 vfs_removexattr(ofs
->workdir
, OVL_XATTR_OPAQUE
);
1271 * We allowed sub-optimal upper fs configuration and don't want to break
1272 * users over kernel upgrade, but we never allowed remote upper fs, so
1273 * we can enforce strict requirements for remote upper fs.
1275 if (ovl_dentry_remote(ofs
->workdir
) &&
1276 (!d_type
|| !rename_whiteout
|| ofs
->noxattr
)) {
1277 pr_err("upper fs missing required features.\n");
1282 /* Check if upper/work fs supports file handles */
1283 fh_type
= ovl_can_decode_fh(ofs
->workdir
->d_sb
);
1284 if (ofs
->config
.index
&& !fh_type
) {
1285 ofs
->config
.index
= false;
1286 pr_warn("upper fs does not support file handles, falling back to index=off.\n");
1289 /* Check if upper fs has 32bit inode numbers */
1290 if (fh_type
!= FILEID_INO32_GEN
)
1291 ofs
->xino_mode
= -1;
1293 /* NFS export of r/w mount depends on index */
1294 if (ofs
->config
.nfs_export
&& !ofs
->config
.index
) {
1295 pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n");
1296 ofs
->config
.nfs_export
= false;
1299 mnt_drop_write(mnt
);
1303 static int ovl_get_workdir(struct super_block
*sb
, struct ovl_fs
*ofs
,
1304 struct path
*upperpath
)
1307 struct path workpath
= { };
1309 err
= ovl_mount_dir(ofs
->config
.workdir
, &workpath
);
1314 if (upperpath
->mnt
!= workpath
.mnt
) {
1315 pr_err("workdir and upperdir must reside under the same mount\n");
1318 if (!ovl_workdir_ok(workpath
.dentry
, upperpath
->dentry
)) {
1319 pr_err("workdir and upperdir must be separate subtrees\n");
1323 ofs
->workbasedir
= dget(workpath
.dentry
);
1325 if (ovl_inuse_trylock(ofs
->workbasedir
)) {
1326 ofs
->workdir_locked
= true;
1328 err
= ovl_report_in_use(ofs
, "workdir");
1333 err
= ovl_setup_trap(sb
, ofs
->workbasedir
, &ofs
->workbasedir_trap
,
1338 err
= ovl_make_workdir(sb
, ofs
, &workpath
);
1341 path_put(&workpath
);
1346 static int ovl_get_indexdir(struct super_block
*sb
, struct ovl_fs
*ofs
,
1347 struct ovl_entry
*oe
, struct path
*upperpath
)
1349 struct vfsmount
*mnt
= ovl_upper_mnt(ofs
);
1352 err
= mnt_want_write(mnt
);
1356 /* Verify lower root is upper root origin */
1357 err
= ovl_verify_origin(upperpath
->dentry
, oe
->lowerstack
[0].dentry
,
1360 pr_err("failed to verify upper root origin\n");
1364 /* index dir will act also as workdir */
1365 iput(ofs
->workdir_trap
);
1366 ofs
->workdir_trap
= NULL
;
1368 ofs
->workdir
= NULL
;
1369 ofs
->indexdir
= ovl_workdir_create(ofs
, OVL_INDEXDIR_NAME
, true);
1370 if (ofs
->indexdir
) {
1371 ofs
->workdir
= dget(ofs
->indexdir
);
1373 err
= ovl_setup_trap(sb
, ofs
->indexdir
, &ofs
->indexdir_trap
,
1379 * Verify upper root is exclusively associated with index dir.
1380 * Older kernels stored upper fh in "trusted.overlay.origin"
1381 * xattr. If that xattr exists, verify that it is a match to
1382 * upper dir file handle. In any case, verify or set xattr
1383 * "trusted.overlay.upper" to indicate that index may have
1384 * directory entries.
1386 if (ovl_check_origin_xattr(ofs
->indexdir
)) {
1387 err
= ovl_verify_set_fh(ofs
->indexdir
, OVL_XATTR_ORIGIN
,
1388 upperpath
->dentry
, true, false);
1390 pr_err("failed to verify index dir 'origin' xattr\n");
1392 err
= ovl_verify_upper(ofs
->indexdir
, upperpath
->dentry
, true);
1394 pr_err("failed to verify index dir 'upper' xattr\n");
1396 /* Cleanup bad/stale/orphan index entries */
1398 err
= ovl_indexdir_cleanup(ofs
);
1400 if (err
|| !ofs
->indexdir
)
1401 pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1404 mnt_drop_write(mnt
);
1408 static bool ovl_lower_uuid_ok(struct ovl_fs
*ofs
, const uuid_t
*uuid
)
1412 if (!ofs
->config
.nfs_export
&& !ovl_upper_mnt(ofs
))
1416 * We allow using single lower with null uuid for index and nfs_export
1417 * for example to support those features with single lower squashfs.
1418 * To avoid regressions in setups of overlay with re-formatted lower
1419 * squashfs, do not allow decoding origin with lower null uuid unless
1420 * user opted-in to one of the new features that require following the
1421 * lower inode of non-dir upper.
1423 if (!ofs
->config
.index
&& !ofs
->config
.metacopy
&& !ofs
->config
.xino
&&
1427 for (i
= 0; i
< ofs
->numfs
; i
++) {
1429 * We use uuid to associate an overlay lower file handle with a
1430 * lower layer, so we can accept lower fs with null uuid as long
1431 * as all lower layers with null uuid are on the same fs.
1432 * if we detect multiple lower fs with the same uuid, we
1433 * disable lower file handle decoding on all of them.
1435 if (ofs
->fs
[i
].is_lower
&&
1436 uuid_equal(&ofs
->fs
[i
].sb
->s_uuid
, uuid
)) {
1437 ofs
->fs
[i
].bad_uuid
= true;
1444 /* Get a unique fsid for the layer */
1445 static int ovl_get_fsid(struct ovl_fs
*ofs
, const struct path
*path
)
1447 struct super_block
*sb
= path
->mnt
->mnt_sb
;
1451 bool bad_uuid
= false;
1453 for (i
= 0; i
< ofs
->numfs
; i
++) {
1454 if (ofs
->fs
[i
].sb
== sb
)
1458 if (!ovl_lower_uuid_ok(ofs
, &sb
->s_uuid
)) {
1460 if (ofs
->config
.index
|| ofs
->config
.nfs_export
) {
1461 ofs
->config
.index
= false;
1462 ofs
->config
.nfs_export
= false;
1463 pr_warn("%s uuid detected in lower fs '%pd2', falling back to index=off,nfs_export=off.\n",
1464 uuid_is_null(&sb
->s_uuid
) ? "null" :
1470 err
= get_anon_bdev(&dev
);
1472 pr_err("failed to get anonymous bdev for lowerpath\n");
1476 ofs
->fs
[ofs
->numfs
].sb
= sb
;
1477 ofs
->fs
[ofs
->numfs
].pseudo_dev
= dev
;
1478 ofs
->fs
[ofs
->numfs
].bad_uuid
= bad_uuid
;
1480 return ofs
->numfs
++;
1483 static int ovl_get_layers(struct super_block
*sb
, struct ovl_fs
*ofs
,
1484 struct path
*stack
, unsigned int numlower
,
1485 struct ovl_layer
*layers
)
1491 ofs
->fs
= kcalloc(numlower
+ 1, sizeof(struct ovl_sb
), GFP_KERNEL
);
1492 if (ofs
->fs
== NULL
)
1495 /* idx/fsid 0 are reserved for upper fs even with lower only overlay */
1499 * All lower layers that share the same fs as upper layer, use the same
1500 * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower
1501 * only overlay to simplify ovl_fs_free().
1502 * is_lower will be set if upper fs is shared with a lower layer.
1504 err
= get_anon_bdev(&ofs
->fs
[0].pseudo_dev
);
1506 pr_err("failed to get anonymous bdev for upper fs\n");
1510 if (ovl_upper_mnt(ofs
)) {
1511 ofs
->fs
[0].sb
= ovl_upper_mnt(ofs
)->mnt_sb
;
1512 ofs
->fs
[0].is_lower
= false;
1515 for (i
= 0; i
< numlower
; i
++) {
1516 struct vfsmount
*mnt
;
1520 err
= fsid
= ovl_get_fsid(ofs
, &stack
[i
]);
1525 * Check if lower root conflicts with this overlay layers before
1526 * checking if it is in-use as upperdir/workdir of "another"
1527 * mount, because we do not bother to check in ovl_is_inuse() if
1528 * the upperdir/workdir is in fact in-use by our
1531 err
= ovl_setup_trap(sb
, stack
[i
].dentry
, &trap
, "lowerdir");
1535 if (ovl_is_inuse(stack
[i
].dentry
)) {
1536 err
= ovl_report_in_use(ofs
, "lowerdir");
1543 mnt
= clone_private_mount(&stack
[i
]);
1546 pr_err("failed to clone lowerpath\n");
1552 * Make lower layers R/O. That way fchmod/fchown on lower file
1553 * will fail instead of modifying lower fs.
1555 mnt
->mnt_flags
|= MNT_READONLY
| MNT_NOATIME
;
1557 layers
[ofs
->numlayer
].trap
= trap
;
1558 layers
[ofs
->numlayer
].mnt
= mnt
;
1559 layers
[ofs
->numlayer
].idx
= ofs
->numlayer
;
1560 layers
[ofs
->numlayer
].fsid
= fsid
;
1561 layers
[ofs
->numlayer
].fs
= &ofs
->fs
[fsid
];
1563 ofs
->fs
[fsid
].is_lower
= true;
1567 * When all layers on same fs, overlay can use real inode numbers.
1568 * With mount option "xino=<on|auto>", mounter declares that there are
1569 * enough free high bits in underlying fs to hold the unique fsid.
1570 * If overlayfs does encounter underlying inodes using the high xino
1571 * bits reserved for fsid, it emits a warning and uses the original
1572 * inode number or a non persistent inode number allocated from a
1575 if (ofs
->numfs
- !ovl_upper_mnt(ofs
) == 1) {
1576 if (ofs
->config
.xino
== OVL_XINO_ON
)
1577 pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
1579 } else if (ofs
->config
.xino
== OVL_XINO_OFF
) {
1580 ofs
->xino_mode
= -1;
1581 } else if (ofs
->xino_mode
< 0) {
1583 * This is a roundup of number of bits needed for encoding
1584 * fsid, where fsid 0 is reserved for upper fs (even with
1585 * lower only overlay) +1 extra bit is reserved for the non
1586 * persistent inode number range that is used for resolving
1587 * xino lower bits overflow.
1589 BUILD_BUG_ON(ilog2(OVL_MAX_STACK
) > 30);
1590 ofs
->xino_mode
= ilog2(ofs
->numfs
- 1) + 2;
1593 if (ofs
->xino_mode
> 0) {
1594 pr_info("\"xino\" feature enabled using %d upper inode bits.\n",
1603 static struct ovl_entry
*ovl_get_lowerstack(struct super_block
*sb
,
1604 const char *lower
, unsigned int numlower
,
1605 struct ovl_fs
*ofs
, struct ovl_layer
*layers
)
1608 struct path
*stack
= NULL
;
1610 struct ovl_entry
*oe
;
1612 if (!ofs
->config
.upperdir
&& numlower
== 1) {
1613 pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
1614 return ERR_PTR(-EINVAL
);
1617 stack
= kcalloc(numlower
, sizeof(struct path
), GFP_KERNEL
);
1619 return ERR_PTR(-ENOMEM
);
1622 for (i
= 0; i
< numlower
; i
++) {
1623 err
= ovl_lower_dir(lower
, &stack
[i
], ofs
, &sb
->s_stack_depth
);
1627 lower
= strchr(lower
, '\0') + 1;
1631 sb
->s_stack_depth
++;
1632 if (sb
->s_stack_depth
> FILESYSTEM_MAX_STACK_DEPTH
) {
1633 pr_err("maximum fs stacking depth exceeded\n");
1637 err
= ovl_get_layers(sb
, ofs
, stack
, numlower
, layers
);
1642 oe
= ovl_alloc_entry(numlower
);
1646 for (i
= 0; i
< numlower
; i
++) {
1647 oe
->lowerstack
[i
].dentry
= dget(stack
[i
].dentry
);
1648 oe
->lowerstack
[i
].layer
= &ofs
->layers
[i
+1];
1652 for (i
= 0; i
< numlower
; i
++)
1653 path_put(&stack
[i
]);
1664 * Check if this layer root is a descendant of:
1665 * - another layer of this overlayfs instance
1666 * - upper/work dir of any overlayfs instance
1668 static int ovl_check_layer(struct super_block
*sb
, struct ovl_fs
*ofs
,
1669 struct dentry
*dentry
, const char *name
)
1671 struct dentry
*next
= dentry
, *parent
;
1677 parent
= dget_parent(next
);
1679 /* Walk back ancestors to root (inclusive) looking for traps */
1680 while (!err
&& parent
!= next
) {
1681 if (ovl_lookup_trap_inode(sb
, parent
)) {
1683 pr_err("overlapping %s path\n", name
);
1684 } else if (ovl_is_inuse(parent
)) {
1685 err
= ovl_report_in_use(ofs
, name
);
1688 parent
= dget_parent(next
);
1698 * Check if any of the layers or work dirs overlap.
1700 static int ovl_check_overlapping_layers(struct super_block
*sb
,
1705 if (ovl_upper_mnt(ofs
)) {
1706 err
= ovl_check_layer(sb
, ofs
, ovl_upper_mnt(ofs
)->mnt_root
,
1712 * Checking workbasedir avoids hitting ovl_is_inuse(parent) of
1713 * this instance and covers overlapping work and index dirs,
1714 * unless work or index dir have been moved since created inside
1715 * workbasedir. In that case, we already have their traps in
1716 * inode cache and we will catch that case on lookup.
1718 err
= ovl_check_layer(sb
, ofs
, ofs
->workbasedir
, "workdir");
1723 for (i
= 1; i
< ofs
->numlayer
; i
++) {
1724 err
= ovl_check_layer(sb
, ofs
,
1725 ofs
->layers
[i
].mnt
->mnt_root
,
1734 static struct dentry
*ovl_get_root(struct super_block
*sb
,
1735 struct dentry
*upperdentry
,
1736 struct ovl_entry
*oe
)
1738 struct dentry
*root
;
1739 struct ovl_path
*lowerpath
= &oe
->lowerstack
[0];
1740 unsigned long ino
= d_inode(lowerpath
->dentry
)->i_ino
;
1741 int fsid
= lowerpath
->layer
->fsid
;
1742 struct ovl_inode_params oip
= {
1743 .upperdentry
= upperdentry
,
1744 .lowerpath
= lowerpath
,
1747 root
= d_make_root(ovl_new_inode(sb
, S_IFDIR
, 0));
1751 root
->d_fsdata
= oe
;
1754 /* Root inode uses upper st_ino/i_ino */
1755 ino
= d_inode(upperdentry
)->i_ino
;
1757 ovl_dentry_set_upper_alias(root
);
1758 if (ovl_is_impuredir(upperdentry
))
1759 ovl_set_flag(OVL_IMPURE
, d_inode(root
));
1762 /* Root is always merge -> can have whiteouts */
1763 ovl_set_flag(OVL_WHITEOUTS
, d_inode(root
));
1764 ovl_dentry_set_flag(OVL_E_CONNECTED
, root
);
1765 ovl_set_upperdata(d_inode(root
));
1766 ovl_inode_init(d_inode(root
), &oip
, ino
, fsid
);
1767 ovl_dentry_update_reval(root
, upperdentry
, DCACHE_OP_WEAK_REVALIDATE
);
1772 static int ovl_fill_super(struct super_block
*sb
, void *data
, int silent
)
1774 struct path upperpath
= { };
1775 struct dentry
*root_dentry
;
1776 struct ovl_entry
*oe
;
1778 struct ovl_layer
*layers
;
1780 char *splitlower
= NULL
;
1781 unsigned int numlower
;
1784 sb
->s_d_op
= &ovl_dentry_operations
;
1787 ofs
= kzalloc(sizeof(struct ovl_fs
), GFP_KERNEL
);
1791 ofs
->creator_cred
= cred
= prepare_creds();
1795 /* Is there a reason anyone would want not to share whiteouts? */
1796 ofs
->share_whiteout
= true;
1798 ofs
->config
.index
= ovl_index_def
;
1799 ofs
->config
.nfs_export
= ovl_nfs_export_def
;
1800 ofs
->config
.xino
= ovl_xino_def();
1801 ofs
->config
.metacopy
= ovl_metacopy_def
;
1802 err
= ovl_parse_opt((char *) data
, &ofs
->config
);
1807 if (!ofs
->config
.lowerdir
) {
1809 pr_err("missing 'lowerdir'\n");
1814 splitlower
= kstrdup(ofs
->config
.lowerdir
, GFP_KERNEL
);
1818 numlower
= ovl_split_lowerdirs(splitlower
);
1819 if (numlower
> OVL_MAX_STACK
) {
1820 pr_err("too many lower directories, limit is %d\n",
1825 layers
= kcalloc(numlower
+ 1, sizeof(struct ovl_layer
), GFP_KERNEL
);
1829 ofs
->layers
= layers
;
1830 /* Layer 0 is reserved for upper even if there's no upper */
1833 sb
->s_stack_depth
= 0;
1834 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
1835 atomic_long_set(&ofs
->last_ino
, 1);
1836 /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
1837 if (ofs
->config
.xino
!= OVL_XINO_OFF
) {
1838 ofs
->xino_mode
= BITS_PER_LONG
- 32;
1839 if (!ofs
->xino_mode
) {
1840 pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n");
1841 ofs
->config
.xino
= OVL_XINO_OFF
;
1845 /* alloc/destroy_inode needed for setting up traps in inode cache */
1846 sb
->s_op
= &ovl_super_operations
;
1848 if (ofs
->config
.upperdir
) {
1849 if (!ofs
->config
.workdir
) {
1850 pr_err("missing 'workdir'\n");
1854 err
= ovl_get_upper(sb
, ofs
, &layers
[0], &upperpath
);
1858 err
= ovl_get_workdir(sb
, ofs
, &upperpath
);
1863 sb
->s_flags
|= SB_RDONLY
;
1865 sb
->s_stack_depth
= ovl_upper_mnt(ofs
)->mnt_sb
->s_stack_depth
;
1866 sb
->s_time_gran
= ovl_upper_mnt(ofs
)->mnt_sb
->s_time_gran
;
1869 oe
= ovl_get_lowerstack(sb
, splitlower
, numlower
, ofs
, layers
);
1874 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1875 if (!ovl_upper_mnt(ofs
))
1876 sb
->s_flags
|= SB_RDONLY
;
1878 if (!ovl_force_readonly(ofs
) && ofs
->config
.index
) {
1879 err
= ovl_get_indexdir(sb
, ofs
, oe
, &upperpath
);
1883 /* Force r/o mount with no index dir */
1885 sb
->s_flags
|= SB_RDONLY
;
1888 err
= ovl_check_overlapping_layers(sb
, ofs
);
1892 /* Show index=off in /proc/mounts for forced r/o mount */
1893 if (!ofs
->indexdir
) {
1894 ofs
->config
.index
= false;
1895 if (ovl_upper_mnt(ofs
) && ofs
->config
.nfs_export
) {
1896 pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n");
1897 ofs
->config
.nfs_export
= false;
1901 if (ofs
->config
.metacopy
&& ofs
->config
.nfs_export
) {
1902 pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
1903 ofs
->config
.nfs_export
= false;
1906 if (ofs
->config
.nfs_export
)
1907 sb
->s_export_op
= &ovl_export_operations
;
1909 /* Never override disk quota limits or use reserved space */
1910 cap_lower(cred
->cap_effective
, CAP_SYS_RESOURCE
);
1912 sb
->s_magic
= OVERLAYFS_SUPER_MAGIC
;
1913 sb
->s_xattr
= ovl_xattr_handlers
;
1914 sb
->s_fs_info
= ofs
;
1915 sb
->s_flags
|= SB_POSIXACL
;
1916 sb
->s_iflags
|= SB_I_SKIP_SYNC
;
1919 root_dentry
= ovl_get_root(sb
, upperpath
.dentry
, oe
);
1923 mntput(upperpath
.mnt
);
1926 sb
->s_root
= root_dentry
;
1931 ovl_entry_stack_free(oe
);
1935 path_put(&upperpath
);
1941 static struct dentry
*ovl_mount(struct file_system_type
*fs_type
, int flags
,
1942 const char *dev_name
, void *raw_data
)
1944 return mount_nodev(fs_type
, flags
, raw_data
, ovl_fill_super
);
1947 static struct file_system_type ovl_fs_type
= {
1948 .owner
= THIS_MODULE
,
1951 .kill_sb
= kill_anon_super
,
1953 MODULE_ALIAS_FS("overlay");
1955 static void ovl_inode_init_once(void *foo
)
1957 struct ovl_inode
*oi
= foo
;
1959 inode_init_once(&oi
->vfs_inode
);
1962 static int __init
ovl_init(void)
1966 ovl_inode_cachep
= kmem_cache_create("ovl_inode",
1967 sizeof(struct ovl_inode
), 0,
1968 (SLAB_RECLAIM_ACCOUNT
|
1969 SLAB_MEM_SPREAD
|SLAB_ACCOUNT
),
1970 ovl_inode_init_once
);
1971 if (ovl_inode_cachep
== NULL
)
1974 err
= ovl_aio_request_cache_init();
1976 err
= register_filesystem(&ovl_fs_type
);
1980 ovl_aio_request_cache_destroy();
1982 kmem_cache_destroy(ovl_inode_cachep
);
1987 static void __exit
ovl_exit(void)
1989 unregister_filesystem(&ovl_fs_type
);
1992 * Make sure all delayed rcu free inodes are flushed before we
1996 kmem_cache_destroy(ovl_inode_cachep
);
1997 ovl_aio_request_cache_destroy();
2000 module_init(ovl_init
);
2001 module_exit(ovl_exit
);