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;
45 /* creds of process who forced instantiation of super block */
46 const struct cred *creator_cred;
51 /* private information held for every overlayfs dentry */
53 struct dentry *__upperdentry;
54 struct ovl_dir_cache *cache;
63 struct path lowerstack[];
66 #define OVL_MAX_STACK 500
68 static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
70 return oe->numlower ? oe->lowerstack[0].dentry : NULL;
73 enum ovl_path_type ovl_path_type(struct dentry *dentry)
75 struct ovl_entry *oe = dentry->d_fsdata;
76 enum ovl_path_type type = 0;
78 if (oe->__upperdentry) {
79 type = __OVL_PATH_UPPER;
82 * Non-dir dentry can hold lower dentry from previous
83 * location. Its purity depends only on opaque flag.
85 if (oe->numlower && S_ISDIR(dentry->d_inode->i_mode))
86 type |= __OVL_PATH_MERGE;
88 type |= __OVL_PATH_PURE;
91 type |= __OVL_PATH_MERGE;
96 static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
98 return lockless_dereference(oe->__upperdentry);
101 void ovl_path_upper(struct dentry *dentry, struct path *path)
103 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
104 struct ovl_entry *oe = dentry->d_fsdata;
106 path->mnt = ofs->upper_mnt;
107 path->dentry = ovl_upperdentry_dereference(oe);
110 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
112 enum ovl_path_type type = ovl_path_type(dentry);
114 if (!OVL_TYPE_UPPER(type))
115 ovl_path_lower(dentry, path);
117 ovl_path_upper(dentry, path);
122 struct dentry *ovl_dentry_upper(struct dentry *dentry)
124 struct ovl_entry *oe = dentry->d_fsdata;
126 return ovl_upperdentry_dereference(oe);
129 struct dentry *ovl_dentry_lower(struct dentry *dentry)
131 struct ovl_entry *oe = dentry->d_fsdata;
133 return __ovl_dentry_lower(oe);
136 struct dentry *ovl_dentry_real(struct dentry *dentry)
138 struct ovl_entry *oe = dentry->d_fsdata;
139 struct dentry *realdentry;
141 realdentry = ovl_upperdentry_dereference(oe);
143 realdentry = __ovl_dentry_lower(oe);
148 struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
150 struct dentry *realdentry;
152 realdentry = ovl_upperdentry_dereference(oe);
156 realdentry = __ovl_dentry_lower(oe);
162 struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
166 struct ovl_fs *ofs = inode->i_sb->s_fs_info;
168 return ofs->upper_mnt;
170 return oe->numlower ? oe->lowerstack[0].mnt : NULL;
174 struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
176 struct ovl_entry *oe = dentry->d_fsdata;
181 bool ovl_is_default_permissions(struct inode *inode)
183 struct ovl_fs *ofs = inode->i_sb->s_fs_info;
185 return ofs->config.default_permissions;
188 void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
190 struct ovl_entry *oe = dentry->d_fsdata;
195 void ovl_path_lower(struct dentry *dentry, struct path *path)
197 struct ovl_entry *oe = dentry->d_fsdata;
199 *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
202 int ovl_want_write(struct dentry *dentry)
204 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
205 return mnt_want_write(ofs->upper_mnt);
208 void ovl_drop_write(struct dentry *dentry)
210 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
211 mnt_drop_write(ofs->upper_mnt);
214 struct dentry *ovl_workdir(struct dentry *dentry)
216 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
220 bool ovl_dentry_is_opaque(struct dentry *dentry)
222 struct ovl_entry *oe = dentry->d_fsdata;
226 void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
228 struct ovl_entry *oe = dentry->d_fsdata;
232 void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
234 struct ovl_entry *oe = dentry->d_fsdata;
236 WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
237 WARN_ON(oe->__upperdentry);
238 BUG_ON(!upperdentry->d_inode);
240 * Make sure upperdentry is consistent before making it visible to
241 * ovl_upperdentry_dereference().
244 oe->__upperdentry = upperdentry;
247 void ovl_dentry_version_inc(struct dentry *dentry)
249 struct ovl_entry *oe = dentry->d_fsdata;
251 WARN_ON(!inode_is_locked(dentry->d_inode));
255 u64 ovl_dentry_version_get(struct dentry *dentry)
257 struct ovl_entry *oe = dentry->d_fsdata;
259 WARN_ON(!inode_is_locked(dentry->d_inode));
263 bool ovl_is_whiteout(struct dentry *dentry)
265 struct inode *inode = dentry->d_inode;
267 return inode && IS_WHITEOUT(inode);
270 const struct cred *ovl_override_creds(struct super_block *sb)
272 struct ovl_fs *ofs = sb->s_fs_info;
274 return override_creds(ofs->creator_cred);
277 static bool ovl_is_opaquedir(struct dentry *dentry)
281 struct inode *inode = dentry->d_inode;
283 if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr)
286 res = inode->i_op->getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1);
287 if (res == 1 && val == 'y')
293 static void ovl_dentry_release(struct dentry *dentry)
295 struct ovl_entry *oe = dentry->d_fsdata;
300 dput(oe->__upperdentry);
301 for (i = 0; i < oe->numlower; i++)
302 dput(oe->lowerstack[i].dentry);
307 static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode)
311 if (d_is_dir(dentry)) {
312 if (!inode || inode == d_inode(dentry))
317 real = ovl_dentry_upper(dentry);
318 if (real && (!inode || inode == d_inode(real)))
321 real = ovl_dentry_lower(dentry);
325 if (!inode || inode == d_inode(real))
328 /* Handle recursion */
329 if (real->d_flags & DCACHE_OP_REAL)
330 return real->d_op->d_real(real, inode);
333 WARN(1, "ovl_d_real(%pd4, %s:%lu\n): real dentry not found\n", dentry,
334 inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
338 static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
340 struct ovl_entry *oe = dentry->d_fsdata;
344 for (i = 0; i < oe->numlower; i++) {
345 struct dentry *d = oe->lowerstack[i].dentry;
347 if (d->d_flags & DCACHE_OP_REVALIDATE) {
348 ret = d->d_op->d_revalidate(d, flags);
352 if (!(flags & LOOKUP_RCU))
361 static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
363 struct ovl_entry *oe = dentry->d_fsdata;
367 for (i = 0; i < oe->numlower; i++) {
368 struct dentry *d = oe->lowerstack[i].dentry;
370 if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
371 ret = d->d_op->d_weak_revalidate(d, flags);
379 static const struct dentry_operations ovl_dentry_operations = {
380 .d_release = ovl_dentry_release,
381 .d_select_inode = ovl_d_select_inode,
382 .d_real = ovl_d_real,
385 static const struct dentry_operations ovl_reval_dentry_operations = {
386 .d_release = ovl_dentry_release,
387 .d_select_inode = ovl_d_select_inode,
388 .d_real = ovl_d_real,
389 .d_revalidate = ovl_dentry_revalidate,
390 .d_weak_revalidate = ovl_dentry_weak_revalidate,
393 static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
395 size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
396 struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
399 oe->numlower = numlower;
404 static bool ovl_dentry_remote(struct dentry *dentry)
406 return dentry->d_flags &
407 (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
410 static bool ovl_dentry_weird(struct dentry *dentry)
412 return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
413 DCACHE_MANAGE_TRANSIT |
418 static inline struct dentry *ovl_lookup_real(struct dentry *dir,
421 struct dentry *dentry;
423 dentry = lookup_hash(name, dir);
425 if (IS_ERR(dentry)) {
426 if (PTR_ERR(dentry) == -ENOENT)
428 } else if (!dentry->d_inode) {
431 } else if (ovl_dentry_weird(dentry)) {
433 /* Don't support traversing automounts and other weirdness */
434 dentry = ERR_PTR(-EREMOTE);
440 * Returns next layer in stack starting from top.
441 * Returns -1 if this is the last layer.
443 int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
445 struct ovl_entry *oe = dentry->d_fsdata;
449 ovl_path_upper(dentry, path);
451 return oe->numlower ? 1 : -1;
454 BUG_ON(idx > oe->numlower);
455 *path = oe->lowerstack[idx - 1];
457 return (idx < oe->numlower) ? idx + 1 : -1;
460 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
463 struct ovl_entry *oe;
464 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
465 struct path *stack = NULL;
466 struct dentry *upperdir, *upperdentry = NULL;
467 unsigned int ctr = 0;
468 struct inode *inode = NULL;
469 bool upperopaque = false;
470 struct dentry *this, *prev = NULL;
474 upperdir = ovl_upperdentry_dereference(poe);
476 this = ovl_lookup_real(upperdir, &dentry->d_name);
482 if (unlikely(ovl_dentry_remote(this))) {
487 if (ovl_is_whiteout(this)) {
491 } else if (poe->numlower && ovl_is_opaquedir(this)) {
495 upperdentry = prev = this;
498 if (!upperopaque && poe->numlower) {
500 stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
505 for (i = 0; !upperopaque && i < poe->numlower; i++) {
507 struct path lowerpath = poe->lowerstack[i];
509 this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
513 * If it's positive, then treat ENAMETOOLONG as ENOENT.
515 if (err == -ENAMETOOLONG && (upperdentry || ctr))
521 if (ovl_is_whiteout(this)) {
526 * Only makes sense to check opaque dir if this is not the
529 if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
532 if (prev && (!S_ISDIR(prev->d_inode->i_mode) ||
533 !S_ISDIR(this->d_inode->i_mode))) {
535 * FIXME: check for upper-opaqueness maybe better done
538 if (prev == upperdentry)
544 * If this is a non-directory then stop here.
546 if (!S_ISDIR(this->d_inode->i_mode))
549 stack[ctr].dentry = this;
550 stack[ctr].mnt = lowerpath.mnt;
557 oe = ovl_alloc_entry(ctr);
562 if (upperdentry || ctr) {
563 struct dentry *realdentry;
565 realdentry = upperdentry ? upperdentry : stack[0].dentry;
568 inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
572 ovl_copyattr(realdentry->d_inode, inode);
575 oe->opaque = upperopaque;
576 oe->__upperdentry = upperdentry;
577 memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
579 dentry->d_fsdata = oe;
580 d_add(dentry, inode);
587 for (i = 0; i < ctr; i++)
588 dput(stack[i].dentry);
596 struct file *ovl_path_open(struct path *path, int flags)
598 return dentry_open(path, flags, current_cred());
601 static void ovl_put_super(struct super_block *sb)
603 struct ovl_fs *ufs = sb->s_fs_info;
607 mntput(ufs->upper_mnt);
608 for (i = 0; i < ufs->numlower; i++)
609 mntput(ufs->lower_mnt[i]);
610 kfree(ufs->lower_mnt);
612 kfree(ufs->config.lowerdir);
613 kfree(ufs->config.upperdir);
614 kfree(ufs->config.workdir);
615 put_cred(ufs->creator_cred);
621 * @sb: The overlayfs super block
622 * @buf: The struct kstatfs to fill in with stats
624 * Get the filesystem statistics. As writes always target the upper layer
625 * filesystem pass the statfs to the upper filesystem (if it exists)
627 static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
629 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
630 struct dentry *root_dentry = dentry->d_sb->s_root;
634 ovl_path_real(root_dentry, &path);
636 err = vfs_statfs(&path, buf);
638 buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
639 buf->f_type = OVERLAYFS_SUPER_MAGIC;
648 * Prints the mount options for a given superblock.
649 * Returns zero; does not fail.
651 static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
653 struct super_block *sb = dentry->d_sb;
654 struct ovl_fs *ufs = sb->s_fs_info;
656 seq_show_option(m, "lowerdir", ufs->config.lowerdir);
657 if (ufs->config.upperdir) {
658 seq_show_option(m, "upperdir", ufs->config.upperdir);
659 seq_show_option(m, "workdir", ufs->config.workdir);
661 if (ufs->config.default_permissions)
662 seq_puts(m, ",default_permissions");
666 static int ovl_remount(struct super_block *sb, int *flags, char *data)
668 struct ovl_fs *ufs = sb->s_fs_info;
670 if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir))
676 static const struct super_operations ovl_super_operations = {
677 .put_super = ovl_put_super,
678 .statfs = ovl_statfs,
679 .show_options = ovl_show_options,
680 .remount_fs = ovl_remount,
687 OPT_DEFAULT_PERMISSIONS,
691 static const match_table_t ovl_tokens = {
692 {OPT_LOWERDIR, "lowerdir=%s"},
693 {OPT_UPPERDIR, "upperdir=%s"},
694 {OPT_WORKDIR, "workdir=%s"},
695 {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
699 static char *ovl_next_opt(char **s)
707 for (p = sbegin; *p; p++) {
712 } else if (*p == ',') {
722 static int ovl_parse_opt(char *opt, struct ovl_config *config)
726 while ((p = ovl_next_opt(&opt)) != NULL) {
728 substring_t args[MAX_OPT_ARGS];
733 token = match_token(p, ovl_tokens, args);
736 kfree(config->upperdir);
737 config->upperdir = match_strdup(&args[0]);
738 if (!config->upperdir)
743 kfree(config->lowerdir);
744 config->lowerdir = match_strdup(&args[0]);
745 if (!config->lowerdir)
750 kfree(config->workdir);
751 config->workdir = match_strdup(&args[0]);
752 if (!config->workdir)
756 case OPT_DEFAULT_PERMISSIONS:
757 config->default_permissions = true;
761 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
766 /* Workdir is useless in non-upper mount */
767 if (!config->upperdir && config->workdir) {
768 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
770 kfree(config->workdir);
771 config->workdir = NULL;
777 #define OVL_WORKDIR_NAME "work"
779 static struct dentry *ovl_workdir_create(struct vfsmount *mnt,
780 struct dentry *dentry)
782 struct inode *dir = dentry->d_inode;
785 bool retried = false;
787 err = mnt_want_write(mnt);
791 inode_lock_nested(dir, I_MUTEX_PARENT);
793 work = lookup_one_len(OVL_WORKDIR_NAME, dentry,
794 strlen(OVL_WORKDIR_NAME));
797 struct kstat stat = {
807 ovl_cleanup(dir, work);
812 err = ovl_create_real(dir, work, &stat, NULL, NULL, true);
828 static void ovl_unescape(char *s)
841 static int ovl_mount_dir_noesc(const char *name, struct path *path)
846 pr_err("overlayfs: empty lowerdir\n");
849 err = kern_path(name, LOOKUP_FOLLOW, path);
851 pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
855 if (ovl_dentry_weird(path->dentry)) {
856 pr_err("overlayfs: filesystem on '%s' not supported\n", name);
859 if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
860 pr_err("overlayfs: '%s' not a directory\n", name);
871 static int ovl_mount_dir(const char *name, struct path *path)
874 char *tmp = kstrdup(name, GFP_KERNEL);
878 err = ovl_mount_dir_noesc(tmp, path);
881 if (ovl_dentry_remote(path->dentry)) {
882 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
892 static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
893 int *stack_depth, bool *remote)
896 struct kstatfs statfs;
898 err = ovl_mount_dir_noesc(name, path);
902 err = vfs_statfs(path, &statfs);
904 pr_err("overlayfs: statfs failed on '%s'\n", name);
907 *namelen = max(*namelen, statfs.f_namelen);
908 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
910 if (ovl_dentry_remote(path->dentry))
921 /* Workdir should not be subdir of upperdir and vice versa */
922 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
926 if (workdir != upperdir) {
927 ok = (lock_rename(workdir, upperdir) == NULL);
928 unlock_rename(workdir, upperdir);
933 static unsigned int ovl_split_lowerdirs(char *str)
935 unsigned int ctr = 1;
938 for (s = d = str;; s++, d++) {
941 } else if (*s == ':') {
953 static int ovl_fill_super(struct super_block *sb, void *data, int silent)
955 struct path upperpath = { NULL, NULL };
956 struct path workpath = { NULL, NULL };
957 struct dentry *root_dentry;
958 struct ovl_entry *oe;
960 struct path *stack = NULL;
963 unsigned int numlower;
964 unsigned int stacklen = 0;
970 ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
974 err = ovl_parse_opt((char *) data, &ufs->config);
976 goto out_free_config;
979 if (!ufs->config.lowerdir) {
981 pr_err("overlayfs: missing 'lowerdir'\n");
982 goto out_free_config;
985 sb->s_stack_depth = 0;
986 sb->s_maxbytes = MAX_LFS_FILESIZE;
987 if (ufs->config.upperdir) {
988 if (!ufs->config.workdir) {
989 pr_err("overlayfs: missing 'workdir'\n");
990 goto out_free_config;
993 err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
995 goto out_free_config;
997 /* Upper fs should not be r/o */
998 if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) {
999 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
1001 goto out_put_upperpath;
1004 err = ovl_mount_dir(ufs->config.workdir, &workpath);
1006 goto out_put_upperpath;
1009 if (upperpath.mnt != workpath.mnt) {
1010 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
1011 goto out_put_workpath;
1013 if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
1014 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
1015 goto out_put_workpath;
1017 sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
1020 lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL);
1022 goto out_put_workpath;
1025 stacklen = ovl_split_lowerdirs(lowertmp);
1026 if (stacklen > OVL_MAX_STACK) {
1027 pr_err("overlayfs: too many lower directries, limit is %d\n",
1029 goto out_free_lowertmp;
1030 } else if (!ufs->config.upperdir && stacklen == 1) {
1031 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
1032 goto out_free_lowertmp;
1035 stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
1037 goto out_free_lowertmp;
1040 for (numlower = 0; numlower < stacklen; numlower++) {
1041 err = ovl_lower_dir(lower, &stack[numlower],
1042 &ufs->lower_namelen, &sb->s_stack_depth,
1045 goto out_put_lowerpath;
1047 lower = strchr(lower, '\0') + 1;
1051 sb->s_stack_depth++;
1052 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
1053 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
1054 goto out_put_lowerpath;
1057 if (ufs->config.upperdir) {
1058 ufs->upper_mnt = clone_private_mount(&upperpath);
1059 err = PTR_ERR(ufs->upper_mnt);
1060 if (IS_ERR(ufs->upper_mnt)) {
1061 pr_err("overlayfs: failed to clone upperpath\n");
1062 goto out_put_lowerpath;
1065 ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
1066 err = PTR_ERR(ufs->workdir);
1067 if (IS_ERR(ufs->workdir)) {
1068 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
1069 ufs->config.workdir, OVL_WORKDIR_NAME, -err);
1070 sb->s_flags |= MS_RDONLY;
1071 ufs->workdir = NULL;
1075 * Upper should support d_type, else whiteouts are visible.
1076 * Given workdir and upper are on same fs, we can do
1077 * iterate_dir() on workdir. This check requires successful
1078 * creation of workdir in previous step.
1081 err = ovl_check_d_type_supported(&workpath);
1083 goto out_put_workdir;
1086 * We allowed this configuration and don't want to
1087 * break users over kernel upgrade. So warn instead
1091 pr_warn("overlayfs: upper fs needs to support d_type.\n");
1096 ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
1097 if (ufs->lower_mnt == NULL)
1098 goto out_put_workdir;
1099 for (i = 0; i < numlower; i++) {
1100 struct vfsmount *mnt = clone_private_mount(&stack[i]);
1104 pr_err("overlayfs: failed to clone lowerpath\n");
1105 goto out_put_lower_mnt;
1108 * Make lower_mnt R/O. That way fchmod/fchown on lower file
1109 * will fail instead of modifying lower fs.
1111 mnt->mnt_flags |= MNT_READONLY;
1113 ufs->lower_mnt[ufs->numlower] = mnt;
1117 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1118 if (!ufs->upper_mnt)
1119 sb->s_flags |= MS_RDONLY;
1122 sb->s_d_op = &ovl_reval_dentry_operations;
1124 sb->s_d_op = &ovl_dentry_operations;
1126 ufs->creator_cred = prepare_creds();
1127 if (!ufs->creator_cred)
1128 goto out_put_lower_mnt;
1131 oe = ovl_alloc_entry(numlower);
1135 root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, oe));
1139 mntput(upperpath.mnt);
1140 for (i = 0; i < numlower; i++)
1141 mntput(stack[i].mnt);
1142 path_put(&workpath);
1145 oe->__upperdentry = upperpath.dentry;
1146 for (i = 0; i < numlower; i++) {
1147 oe->lowerstack[i].dentry = stack[i].dentry;
1148 oe->lowerstack[i].mnt = ufs->lower_mnt[i];
1152 root_dentry->d_fsdata = oe;
1154 ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode,
1155 root_dentry->d_inode);
1157 sb->s_magic = OVERLAYFS_SUPER_MAGIC;
1158 sb->s_op = &ovl_super_operations;
1159 sb->s_root = root_dentry;
1160 sb->s_fs_info = ufs;
1167 put_cred(ufs->creator_cred);
1169 for (i = 0; i < ufs->numlower; i++)
1170 mntput(ufs->lower_mnt[i]);
1171 kfree(ufs->lower_mnt);
1174 mntput(ufs->upper_mnt);
1176 for (i = 0; i < numlower; i++)
1177 path_put(&stack[i]);
1182 path_put(&workpath);
1184 path_put(&upperpath);
1186 kfree(ufs->config.lowerdir);
1187 kfree(ufs->config.upperdir);
1188 kfree(ufs->config.workdir);
1194 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
1195 const char *dev_name, void *raw_data)
1197 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
1200 static struct file_system_type ovl_fs_type = {
1201 .owner = THIS_MODULE,
1204 .kill_sb = kill_anon_super,
1206 MODULE_ALIAS_FS("overlay");
1208 static int __init ovl_init(void)
1210 return register_filesystem(&ovl_fs_type);
1213 static void __exit ovl_exit(void)
1215 unregister_filesystem(&ovl_fs_type);
1218 module_init(ovl_init);
1219 module_exit(ovl_exit);