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))
267 if (!ovl_should_sync(ofs))
270 * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC).
271 * All the super blocks will be iterated, including upper_sb.
273 * If this is a syncfs(2) call, then we do need to call
274 * sync_filesystem() on upper_sb, but enough if we do it when being
275 * called with wait == 1.
280 upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
282 down_read(&upper_sb->s_umount);
283 ret = sync_filesystem(upper_sb);
284 up_read(&upper_sb->s_umount);
291 * @sb: The overlayfs super block
292 * @buf: The struct kstatfs to fill in with stats
294 * Get the filesystem statistics. As writes always target the upper layer
295 * filesystem pass the statfs to the upper filesystem (if it exists)
297 static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
299 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
300 struct dentry *root_dentry = dentry->d_sb->s_root;
304 ovl_path_real(root_dentry, &path);
306 err = vfs_statfs(&path, buf);
308 buf->f_namelen = ofs->namelen;
309 buf->f_type = OVERLAYFS_SUPER_MAGIC;
315 /* Will this overlay be forced to mount/remount ro? */
316 static bool ovl_force_readonly(struct ovl_fs *ofs)
318 return (!ovl_upper_mnt(ofs) || !ofs->workdir);
321 static const char *ovl_redirect_mode_def(void)
323 return ovl_redirect_dir_def ? "on" : "off";
326 static const char * const ovl_xino_str[] = {
332 static inline int ovl_xino_def(void)
334 return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
340 * Prints the mount options for a given superblock.
341 * Returns zero; does not fail.
343 static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
345 struct super_block *sb = dentry->d_sb;
346 struct ovl_fs *ofs = sb->s_fs_info;
348 seq_show_option(m, "lowerdir", ofs->config.lowerdir);
349 if (ofs->config.upperdir) {
350 seq_show_option(m, "upperdir", ofs->config.upperdir);
351 seq_show_option(m, "workdir", ofs->config.workdir);
353 if (ofs->config.default_permissions)
354 seq_puts(m, ",default_permissions");
355 if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0)
356 seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode);
357 if (ofs->config.index != ovl_index_def)
358 seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
359 if (ofs->config.nfs_export != ovl_nfs_export_def)
360 seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
362 if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(sb))
363 seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
364 if (ofs->config.metacopy != ovl_metacopy_def)
365 seq_printf(m, ",metacopy=%s",
366 ofs->config.metacopy ? "on" : "off");
367 if (ofs->config.ovl_volatile)
368 seq_puts(m, ",volatile");
372 static int ovl_remount(struct super_block *sb, int *flags, char *data)
374 struct ovl_fs *ofs = sb->s_fs_info;
375 struct super_block *upper_sb;
378 if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
381 if (*flags & SB_RDONLY && !sb_rdonly(sb)) {
382 upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
383 if (ovl_should_sync(ofs)) {
384 down_read(&upper_sb->s_umount);
385 ret = sync_filesystem(upper_sb);
386 up_read(&upper_sb->s_umount);
393 static const struct super_operations ovl_super_operations = {
394 .alloc_inode = ovl_alloc_inode,
395 .free_inode = ovl_free_inode,
396 .destroy_inode = ovl_destroy_inode,
397 .drop_inode = generic_delete_inode,
398 .put_super = ovl_put_super,
399 .sync_fs = ovl_sync_fs,
400 .statfs = ovl_statfs,
401 .show_options = ovl_show_options,
402 .remount_fs = ovl_remount,
409 OPT_DEFAULT_PERMISSIONS,
424 static const match_table_t ovl_tokens = {
425 {OPT_LOWERDIR, "lowerdir=%s"},
426 {OPT_UPPERDIR, "upperdir=%s"},
427 {OPT_WORKDIR, "workdir=%s"},
428 {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
429 {OPT_REDIRECT_DIR, "redirect_dir=%s"},
430 {OPT_INDEX_ON, "index=on"},
431 {OPT_INDEX_OFF, "index=off"},
432 {OPT_NFS_EXPORT_ON, "nfs_export=on"},
433 {OPT_NFS_EXPORT_OFF, "nfs_export=off"},
434 {OPT_XINO_ON, "xino=on"},
435 {OPT_XINO_OFF, "xino=off"},
436 {OPT_XINO_AUTO, "xino=auto"},
437 {OPT_METACOPY_ON, "metacopy=on"},
438 {OPT_METACOPY_OFF, "metacopy=off"},
439 {OPT_VOLATILE, "volatile"},
443 static char *ovl_next_opt(char **s)
451 for (p = sbegin; *p; p++) {
456 } else if (*p == ',') {
466 static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
468 if (strcmp(mode, "on") == 0) {
469 config->redirect_dir = true;
471 * Does not make sense to have redirect creation without
472 * redirect following.
474 config->redirect_follow = true;
475 } else if (strcmp(mode, "follow") == 0) {
476 config->redirect_follow = true;
477 } else if (strcmp(mode, "off") == 0) {
478 if (ovl_redirect_always_follow)
479 config->redirect_follow = true;
480 } else if (strcmp(mode, "nofollow") != 0) {
481 pr_err("bad mount option \"redirect_dir=%s\"\n",
489 static int ovl_parse_opt(char *opt, struct ovl_config *config)
493 bool metacopy_opt = false, redirect_opt = false;
494 bool nfs_export_opt = false, index_opt = false;
496 config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
497 if (!config->redirect_mode)
500 while ((p = ovl_next_opt(&opt)) != NULL) {
502 substring_t args[MAX_OPT_ARGS];
507 token = match_token(p, ovl_tokens, args);
510 kfree(config->upperdir);
511 config->upperdir = match_strdup(&args[0]);
512 if (!config->upperdir)
517 kfree(config->lowerdir);
518 config->lowerdir = match_strdup(&args[0]);
519 if (!config->lowerdir)
524 kfree(config->workdir);
525 config->workdir = match_strdup(&args[0]);
526 if (!config->workdir)
530 case OPT_DEFAULT_PERMISSIONS:
531 config->default_permissions = true;
534 case OPT_REDIRECT_DIR:
535 kfree(config->redirect_mode);
536 config->redirect_mode = match_strdup(&args[0]);
537 if (!config->redirect_mode)
543 config->index = true;
548 config->index = false;
552 case OPT_NFS_EXPORT_ON:
553 config->nfs_export = true;
554 nfs_export_opt = true;
557 case OPT_NFS_EXPORT_OFF:
558 config->nfs_export = false;
559 nfs_export_opt = true;
563 config->xino = OVL_XINO_ON;
567 config->xino = OVL_XINO_OFF;
571 config->xino = OVL_XINO_AUTO;
574 case OPT_METACOPY_ON:
575 config->metacopy = true;
579 case OPT_METACOPY_OFF:
580 config->metacopy = false;
585 config->ovl_volatile = true;
589 pr_err("unrecognized mount option \"%s\" or missing value\n",
595 /* Workdir/index are useless in non-upper mount */
596 if (!config->upperdir) {
597 if (config->workdir) {
598 pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
600 kfree(config->workdir);
601 config->workdir = NULL;
603 if (config->index && index_opt) {
604 pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n");
607 config->index = false;
610 if (!config->upperdir && config->ovl_volatile) {
611 pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n");
612 config->ovl_volatile = false;
615 err = ovl_parse_redirect_mode(config, config->redirect_mode);
620 * This is to make the logic below simpler. It doesn't make any other
621 * difference, since config->redirect_dir is only used for upper.
623 if (!config->upperdir && config->redirect_follow)
624 config->redirect_dir = true;
626 /* Resolve metacopy -> redirect_dir dependency */
627 if (config->metacopy && !config->redirect_dir) {
628 if (metacopy_opt && redirect_opt) {
629 pr_err("conflicting options: metacopy=on,redirect_dir=%s\n",
630 config->redirect_mode);
635 * There was an explicit redirect_dir=... that resulted
638 pr_info("disabling metacopy due to redirect_dir=%s\n",
639 config->redirect_mode);
640 config->metacopy = false;
642 /* Automatically enable redirect otherwise. */
643 config->redirect_follow = config->redirect_dir = true;
647 /* Resolve nfs_export -> index dependency */
648 if (config->nfs_export && !config->index) {
649 if (!config->upperdir && config->redirect_follow) {
650 pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
651 config->nfs_export = false;
652 } else if (nfs_export_opt && index_opt) {
653 pr_err("conflicting options: nfs_export=on,index=off\n");
655 } else if (index_opt) {
657 * There was an explicit index=off that resulted
660 pr_info("disabling nfs_export due to index=off\n");
661 config->nfs_export = false;
663 /* Automatically enable index otherwise. */
664 config->index = true;
668 /* Resolve nfs_export -> !metacopy dependency */
669 if (config->nfs_export && config->metacopy) {
670 if (nfs_export_opt && metacopy_opt) {
671 pr_err("conflicting options: nfs_export=on,metacopy=on\n");
676 * There was an explicit metacopy=on that resulted
679 pr_info("disabling nfs_export due to metacopy=on\n");
680 config->nfs_export = false;
683 * There was an explicit nfs_export=on that resulted
686 pr_info("disabling metacopy due to nfs_export=on\n");
687 config->metacopy = false;
694 #define OVL_WORKDIR_NAME "work"
695 #define OVL_INDEXDIR_NAME "index"
697 static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
698 const char *name, bool persist)
700 struct inode *dir = ofs->workbasedir->d_inode;
701 struct vfsmount *mnt = ovl_upper_mnt(ofs);
704 bool retried = false;
706 inode_lock_nested(dir, I_MUTEX_PARENT);
708 work = lookup_one_len(name, ofs->workbasedir, strlen(name));
711 struct iattr attr = {
712 .ia_valid = ATTR_MODE,
713 .ia_mode = S_IFDIR | 0,
725 err = ovl_workdir_cleanup(dir, mnt, work, 0);
727 if (err == -EINVAL) {
734 work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode));
740 * Try to remove POSIX ACL xattrs from workdir. We are good if:
742 * a) success (there was a POSIX ACL xattr and was removed)
743 * b) -ENODATA (there was no POSIX ACL xattr)
744 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
746 * There are various other error values that could effectively
747 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
748 * if the xattr name is too long), but the set of filesystems
749 * allowed as upper are limited to "normal" ones, where checking
750 * for the above two errors is sufficient.
752 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
753 if (err && err != -ENODATA && err != -EOPNOTSUPP)
756 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
757 if (err && err != -ENODATA && err != -EOPNOTSUPP)
760 /* Clear any inherited mode bits */
761 inode_lock(work->d_inode);
762 err = notify_change(work, &attr, NULL);
763 inode_unlock(work->d_inode);
777 pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n",
778 ofs->config.workdir, name, -err);
783 static void ovl_unescape(char *s)
796 static int ovl_mount_dir_noesc(const char *name, struct path *path)
801 pr_err("empty lowerdir\n");
804 err = kern_path(name, LOOKUP_FOLLOW, path);
806 pr_err("failed to resolve '%s': %i\n", name, err);
810 if (ovl_dentry_weird(path->dentry)) {
811 pr_err("filesystem on '%s' not supported\n", name);
814 if (!d_is_dir(path->dentry)) {
815 pr_err("'%s' not a directory\n", name);
826 static int ovl_mount_dir(const char *name, struct path *path)
829 char *tmp = kstrdup(name, GFP_KERNEL);
833 err = ovl_mount_dir_noesc(tmp, path);
835 if (!err && path->dentry->d_flags & DCACHE_OP_REAL) {
836 pr_err("filesystem on '%s' not supported as upperdir\n",
846 static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
849 struct kstatfs statfs;
850 int err = vfs_statfs(path, &statfs);
853 pr_err("statfs failed on '%s'\n", name);
855 ofs->namelen = max(ofs->namelen, statfs.f_namelen);
860 static int ovl_lower_dir(const char *name, struct path *path,
861 struct ovl_fs *ofs, int *stack_depth)
866 err = ovl_mount_dir_noesc(name, path);
870 err = ovl_check_namelen(path, ofs, name);
874 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
877 * The inodes index feature and NFS export need to encode and decode
878 * file handles, so they require that all layers support them.
880 fh_type = ovl_can_decode_fh(path->dentry->d_sb);
881 if ((ofs->config.nfs_export ||
882 (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
883 ofs->config.index = false;
884 ofs->config.nfs_export = false;
885 pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
889 /* Check if lower fs has 32bit inode numbers */
890 if (fh_type != FILEID_INO32_GEN)
896 /* Workdir should not be subdir of upperdir and vice versa */
897 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
901 if (workdir != upperdir) {
902 ok = (lock_rename(workdir, upperdir) == NULL);
903 unlock_rename(workdir, upperdir);
908 static unsigned int ovl_split_lowerdirs(char *str)
910 unsigned int ctr = 1;
913 for (s = d = str;; s++, d++) {
916 } else if (*s == ':') {
928 static int __maybe_unused
929 ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
930 struct dentry *dentry, struct inode *inode,
931 const char *name, void *buffer, size_t size)
933 return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
936 static int __maybe_unused
937 ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
938 struct dentry *dentry, struct inode *inode,
939 const char *name, const void *value,
940 size_t size, int flags)
942 struct dentry *workdir = ovl_workdir(dentry);
943 struct inode *realinode = ovl_inode_real(inode);
944 struct posix_acl *acl = NULL;
947 /* Check that everything is OK before copy-up */
949 acl = posix_acl_from_xattr(&init_user_ns, value, size);
954 if (!IS_POSIXACL(d_inode(workdir)))
955 goto out_acl_release;
956 if (!realinode->i_op->set_acl)
957 goto out_acl_release;
958 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
959 err = acl ? -EACCES : 0;
960 goto out_acl_release;
963 if (!inode_owner_or_capable(inode))
964 goto out_acl_release;
966 posix_acl_release(acl);
969 * Check if sgid bit needs to be cleared (actual setacl operation will
970 * be done with mounter's capabilities and so that won't do it for us).
972 if (unlikely(inode->i_mode & S_ISGID) &&
973 handler->flags == ACL_TYPE_ACCESS &&
974 !in_group_p(inode->i_gid) &&
975 !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
976 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
978 err = ovl_setattr(dentry, &iattr);
983 err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
985 ovl_copyattr(ovl_inode_real(inode), inode);
990 posix_acl_release(acl);
994 static int ovl_own_xattr_get(const struct xattr_handler *handler,
995 struct dentry *dentry, struct inode *inode,
996 const char *name, void *buffer, size_t size)
1001 static int ovl_own_xattr_set(const struct xattr_handler *handler,
1002 struct dentry *dentry, struct inode *inode,
1003 const char *name, const void *value,
1004 size_t size, int flags)
1009 static int ovl_other_xattr_get(const struct xattr_handler *handler,
1010 struct dentry *dentry, struct inode *inode,
1011 const char *name, void *buffer, size_t size)
1013 return ovl_xattr_get(dentry, inode, name, buffer, size);
1016 static int ovl_other_xattr_set(const struct xattr_handler *handler,
1017 struct dentry *dentry, struct inode *inode,
1018 const char *name, const void *value,
1019 size_t size, int flags)
1021 return ovl_xattr_set(dentry, inode, name, value, size, flags);
1024 static const struct xattr_handler __maybe_unused
1025 ovl_posix_acl_access_xattr_handler = {
1026 .name = XATTR_NAME_POSIX_ACL_ACCESS,
1027 .flags = ACL_TYPE_ACCESS,
1028 .get = ovl_posix_acl_xattr_get,
1029 .set = ovl_posix_acl_xattr_set,
1032 static const struct xattr_handler __maybe_unused
1033 ovl_posix_acl_default_xattr_handler = {
1034 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
1035 .flags = ACL_TYPE_DEFAULT,
1036 .get = ovl_posix_acl_xattr_get,
1037 .set = ovl_posix_acl_xattr_set,
1040 static const struct xattr_handler ovl_own_xattr_handler = {
1041 .prefix = OVL_XATTR_PREFIX,
1042 .get = ovl_own_xattr_get,
1043 .set = ovl_own_xattr_set,
1046 static const struct xattr_handler ovl_other_xattr_handler = {
1047 .prefix = "", /* catch all */
1048 .get = ovl_other_xattr_get,
1049 .set = ovl_other_xattr_set,
1052 static const struct xattr_handler *ovl_xattr_handlers[] = {
1053 #ifdef CONFIG_FS_POSIX_ACL
1054 &ovl_posix_acl_access_xattr_handler,
1055 &ovl_posix_acl_default_xattr_handler,
1057 &ovl_own_xattr_handler,
1058 &ovl_other_xattr_handler,
1062 static int ovl_setup_trap(struct super_block *sb, struct dentry *dir,
1063 struct inode **ptrap, const char *name)
1068 trap = ovl_get_trap_inode(sb, dir);
1069 err = PTR_ERR_OR_ZERO(trap);
1072 pr_err("conflicting %s path\n", name);
1081 * Determine how we treat concurrent use of upperdir/workdir based on the
1082 * index feature. This is papering over mount leaks of container runtimes,
1083 * for example, an old overlay mount is leaked and now its upperdir is
1084 * attempted to be used as a lower layer in a new overlay mount.
1086 static int ovl_report_in_use(struct ovl_fs *ofs, const char *name)
1088 if (ofs->config.index) {
1089 pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n",
1093 pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n",
1099 static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
1100 struct ovl_layer *upper_layer, struct path *upperpath)
1102 struct vfsmount *upper_mnt;
1105 err = ovl_mount_dir(ofs->config.upperdir, upperpath);
1109 /* Upper fs should not be r/o */
1110 if (sb_rdonly(upperpath->mnt->mnt_sb)) {
1111 pr_err("upper fs is r/o, try multi-lower layers mount\n");
1116 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
1120 err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap,
1125 upper_mnt = clone_private_mount(upperpath);
1126 err = PTR_ERR(upper_mnt);
1127 if (IS_ERR(upper_mnt)) {
1128 pr_err("failed to clone upperpath\n");
1132 /* Don't inherit atime flags */
1133 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
1134 upper_layer->mnt = upper_mnt;
1135 upper_layer->idx = 0;
1136 upper_layer->fsid = 0;
1139 * Inherit SB_NOSEC flag from upperdir.
1141 * This optimization changes behavior when a security related attribute
1142 * (suid/sgid/security.*) is changed on an underlying layer. This is
1143 * okay because we don't yet have guarantees in that case, but it will
1144 * need careful treatment once we want to honour changes to underlying
1147 if (upper_mnt->mnt_sb->s_flags & SB_NOSEC)
1148 sb->s_flags |= SB_NOSEC;
1150 if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) {
1151 ofs->upperdir_locked = true;
1153 err = ovl_report_in_use(ofs, "upperdir");
1164 * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and
1165 * negative values if error is encountered.
1167 static int ovl_check_rename_whiteout(struct dentry *workdir)
1169 struct inode *dir = d_inode(workdir);
1170 struct dentry *temp;
1171 struct dentry *dest;
1172 struct dentry *whiteout;
1173 struct name_snapshot name;
1176 inode_lock_nested(dir, I_MUTEX_PARENT);
1178 temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0));
1179 err = PTR_ERR(temp);
1183 dest = ovl_lookup_temp(workdir);
1184 err = PTR_ERR(dest);
1190 /* Name is inline and stable - using snapshot as a copy helper */
1191 take_dentry_name_snapshot(&name, temp);
1192 err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT);
1199 whiteout = lookup_one_len(name.name.name, workdir, name.name.len);
1200 err = PTR_ERR(whiteout);
1201 if (IS_ERR(whiteout))
1204 err = ovl_is_whiteout(whiteout);
1206 /* Best effort cleanup of whiteout and temp file */
1208 ovl_cleanup(dir, whiteout);
1212 ovl_cleanup(dir, temp);
1213 release_dentry_name_snapshot(&name);
1223 static struct dentry *ovl_lookup_or_create(struct dentry *parent,
1224 const char *name, umode_t mode)
1226 size_t len = strlen(name);
1227 struct dentry *child;
1229 inode_lock_nested(parent->d_inode, I_MUTEX_PARENT);
1230 child = lookup_one_len(name, parent, len);
1231 if (!IS_ERR(child) && !child->d_inode)
1232 child = ovl_create_real(parent->d_inode, child,
1234 inode_unlock(parent->d_inode);
1241 * Creates $workdir/work/incompat/volatile/dirty file if it is not already
1244 static int ovl_create_volatile_dirty(struct ovl_fs *ofs)
1247 struct dentry *d = dget(ofs->workbasedir);
1248 static const char *const volatile_path[] = {
1249 OVL_WORKDIR_NAME, "incompat", "volatile", "dirty"
1251 const char *const *name = volatile_path;
1253 for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) {
1254 d = ovl_lookup_or_create(d, *name, ctr > 1 ? S_IFDIR : S_IFREG);
1262 static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
1263 struct path *workpath)
1265 struct vfsmount *mnt = ovl_upper_mnt(ofs);
1266 struct dentry *temp, *workdir;
1267 bool rename_whiteout;
1272 err = mnt_want_write(mnt);
1276 workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
1277 err = PTR_ERR(workdir);
1278 if (IS_ERR_OR_NULL(workdir))
1281 ofs->workdir = workdir;
1283 err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir");
1288 * Upper should support d_type, else whiteouts are visible. Given
1289 * workdir and upper are on same fs, we can do iterate_dir() on
1290 * workdir. This check requires successful creation of workdir in
1293 err = ovl_check_d_type_supported(workpath);
1299 pr_warn("upper fs needs to support d_type.\n");
1301 /* Check if upper/work fs supports O_TMPFILE */
1302 temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
1303 ofs->tmpfile = !IS_ERR(temp);
1307 pr_warn("upper fs does not support tmpfile.\n");
1310 /* Check if upper/work fs supports RENAME_WHITEOUT */
1311 err = ovl_check_rename_whiteout(ofs->workdir);
1315 rename_whiteout = err;
1316 if (!rename_whiteout)
1317 pr_warn("upper fs does not support RENAME_WHITEOUT.\n");
1320 * Check if upper/work fs supports trusted.overlay.* xattr
1322 err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
1324 ofs->noxattr = true;
1325 ofs->config.index = false;
1326 ofs->config.metacopy = false;
1327 pr_warn("upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
1330 ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE);
1334 * We allowed sub-optimal upper fs configuration and don't want to break
1335 * users over kernel upgrade, but we never allowed remote upper fs, so
1336 * we can enforce strict requirements for remote upper fs.
1338 if (ovl_dentry_remote(ofs->workdir) &&
1339 (!d_type || !rename_whiteout || ofs->noxattr)) {
1340 pr_err("upper fs missing required features.\n");
1346 * For volatile mount, create a incompat/volatile/dirty file to keep
1349 if (ofs->config.ovl_volatile) {
1350 err = ovl_create_volatile_dirty(ofs);
1352 pr_err("Failed to create volatile/dirty file.\n");
1357 /* Check if upper/work fs supports file handles */
1358 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
1359 if (ofs->config.index && !fh_type) {
1360 ofs->config.index = false;
1361 pr_warn("upper fs does not support file handles, falling back to index=off.\n");
1364 /* Check if upper fs has 32bit inode numbers */
1365 if (fh_type != FILEID_INO32_GEN)
1366 ofs->xino_mode = -1;
1368 /* NFS export of r/w mount depends on index */
1369 if (ofs->config.nfs_export && !ofs->config.index) {
1370 pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n");
1371 ofs->config.nfs_export = false;
1374 mnt_drop_write(mnt);
1378 static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs,
1379 struct path *upperpath)
1382 struct path workpath = { };
1384 err = ovl_mount_dir(ofs->config.workdir, &workpath);
1389 if (upperpath->mnt != workpath.mnt) {
1390 pr_err("workdir and upperdir must reside under the same mount\n");
1393 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) {
1394 pr_err("workdir and upperdir must be separate subtrees\n");
1398 ofs->workbasedir = dget(workpath.dentry);
1400 if (ovl_inuse_trylock(ofs->workbasedir)) {
1401 ofs->workdir_locked = true;
1403 err = ovl_report_in_use(ofs, "workdir");
1408 err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap,
1413 err = ovl_make_workdir(sb, ofs, &workpath);
1416 path_put(&workpath);
1421 static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
1422 struct ovl_entry *oe, struct path *upperpath)
1424 struct vfsmount *mnt = ovl_upper_mnt(ofs);
1425 struct dentry *indexdir;
1428 err = mnt_want_write(mnt);
1432 /* Verify lower root is upper root origin */
1433 err = ovl_verify_origin(ofs, upperpath->dentry,
1434 oe->lowerstack[0].dentry, true);
1436 pr_err("failed to verify upper root origin\n");
1440 /* index dir will act also as workdir */
1441 iput(ofs->workdir_trap);
1442 ofs->workdir_trap = NULL;
1444 ofs->workdir = NULL;
1445 indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
1446 if (IS_ERR(indexdir)) {
1447 err = PTR_ERR(indexdir);
1448 } else if (indexdir) {
1449 ofs->indexdir = indexdir;
1450 ofs->workdir = dget(indexdir);
1452 err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap,
1458 * Verify upper root is exclusively associated with index dir.
1459 * Older kernels stored upper fh in "trusted.overlay.origin"
1460 * xattr. If that xattr exists, verify that it is a match to
1461 * upper dir file handle. In any case, verify or set xattr
1462 * "trusted.overlay.upper" to indicate that index may have
1463 * directory entries.
1465 if (ovl_check_origin_xattr(ofs, ofs->indexdir)) {
1466 err = ovl_verify_set_fh(ofs, ofs->indexdir,
1468 upperpath->dentry, true, false);
1470 pr_err("failed to verify index dir 'origin' xattr\n");
1472 err = ovl_verify_upper(ofs, ofs->indexdir, upperpath->dentry,
1475 pr_err("failed to verify index dir 'upper' xattr\n");
1477 /* Cleanup bad/stale/orphan index entries */
1479 err = ovl_indexdir_cleanup(ofs);
1481 if (err || !ofs->indexdir)
1482 pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1485 mnt_drop_write(mnt);
1489 static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
1493 if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs))
1497 * We allow using single lower with null uuid for index and nfs_export
1498 * for example to support those features with single lower squashfs.
1499 * To avoid regressions in setups of overlay with re-formatted lower
1500 * squashfs, do not allow decoding origin with lower null uuid unless
1501 * user opted-in to one of the new features that require following the
1502 * lower inode of non-dir upper.
1504 if (!ofs->config.index && !ofs->config.metacopy && !ofs->config.xino &&
1508 for (i = 0; i < ofs->numfs; i++) {
1510 * We use uuid to associate an overlay lower file handle with a
1511 * lower layer, so we can accept lower fs with null uuid as long
1512 * as all lower layers with null uuid are on the same fs.
1513 * if we detect multiple lower fs with the same uuid, we
1514 * disable lower file handle decoding on all of them.
1516 if (ofs->fs[i].is_lower &&
1517 uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
1518 ofs->fs[i].bad_uuid = true;
1525 /* Get a unique fsid for the layer */
1526 static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
1528 struct super_block *sb = path->mnt->mnt_sb;
1532 bool bad_uuid = false;
1534 for (i = 0; i < ofs->numfs; i++) {
1535 if (ofs->fs[i].sb == sb)
1539 if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) {
1541 if (ofs->config.index || ofs->config.nfs_export) {
1542 ofs->config.index = false;
1543 ofs->config.nfs_export = false;
1544 pr_warn("%s uuid detected in lower fs '%pd2', falling back to index=off,nfs_export=off.\n",
1545 uuid_is_null(&sb->s_uuid) ? "null" :
1551 err = get_anon_bdev(&dev);
1553 pr_err("failed to get anonymous bdev for lowerpath\n");
1557 ofs->fs[ofs->numfs].sb = sb;
1558 ofs->fs[ofs->numfs].pseudo_dev = dev;
1559 ofs->fs[ofs->numfs].bad_uuid = bad_uuid;
1561 return ofs->numfs++;
1564 static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
1565 struct path *stack, unsigned int numlower,
1566 struct ovl_layer *layers)
1572 ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL);
1573 if (ofs->fs == NULL)
1576 /* idx/fsid 0 are reserved for upper fs even with lower only overlay */
1580 * All lower layers that share the same fs as upper layer, use the same
1581 * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower
1582 * only overlay to simplify ovl_fs_free().
1583 * is_lower will be set if upper fs is shared with a lower layer.
1585 err = get_anon_bdev(&ofs->fs[0].pseudo_dev);
1587 pr_err("failed to get anonymous bdev for upper fs\n");
1591 if (ovl_upper_mnt(ofs)) {
1592 ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb;
1593 ofs->fs[0].is_lower = false;
1596 for (i = 0; i < numlower; i++) {
1597 struct vfsmount *mnt;
1601 err = fsid = ovl_get_fsid(ofs, &stack[i]);
1606 * Check if lower root conflicts with this overlay layers before
1607 * checking if it is in-use as upperdir/workdir of "another"
1608 * mount, because we do not bother to check in ovl_is_inuse() if
1609 * the upperdir/workdir is in fact in-use by our
1612 err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir");
1616 if (ovl_is_inuse(stack[i].dentry)) {
1617 err = ovl_report_in_use(ofs, "lowerdir");
1624 mnt = clone_private_mount(&stack[i]);
1627 pr_err("failed to clone lowerpath\n");
1633 * Make lower layers R/O. That way fchmod/fchown on lower file
1634 * will fail instead of modifying lower fs.
1636 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
1638 layers[ofs->numlayer].trap = trap;
1639 layers[ofs->numlayer].mnt = mnt;
1640 layers[ofs->numlayer].idx = ofs->numlayer;
1641 layers[ofs->numlayer].fsid = fsid;
1642 layers[ofs->numlayer].fs = &ofs->fs[fsid];
1644 ofs->fs[fsid].is_lower = true;
1648 * When all layers on same fs, overlay can use real inode numbers.
1649 * With mount option "xino=<on|auto>", mounter declares that there are
1650 * enough free high bits in underlying fs to hold the unique fsid.
1651 * If overlayfs does encounter underlying inodes using the high xino
1652 * bits reserved for fsid, it emits a warning and uses the original
1653 * inode number or a non persistent inode number allocated from a
1656 if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) {
1657 if (ofs->config.xino == OVL_XINO_ON)
1658 pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
1660 } else if (ofs->config.xino == OVL_XINO_OFF) {
1661 ofs->xino_mode = -1;
1662 } else if (ofs->xino_mode < 0) {
1664 * This is a roundup of number of bits needed for encoding
1665 * fsid, where fsid 0 is reserved for upper fs (even with
1666 * lower only overlay) +1 extra bit is reserved for the non
1667 * persistent inode number range that is used for resolving
1668 * xino lower bits overflow.
1670 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30);
1671 ofs->xino_mode = ilog2(ofs->numfs - 1) + 2;
1674 if (ofs->xino_mode > 0) {
1675 pr_info("\"xino\" feature enabled using %d upper inode bits.\n",
1684 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
1685 const char *lower, unsigned int numlower,
1686 struct ovl_fs *ofs, struct ovl_layer *layers)
1689 struct path *stack = NULL;
1691 struct ovl_entry *oe;
1693 if (!ofs->config.upperdir && numlower == 1) {
1694 pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
1695 return ERR_PTR(-EINVAL);
1698 stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL);
1700 return ERR_PTR(-ENOMEM);
1703 for (i = 0; i < numlower; i++) {
1704 err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth);
1708 lower = strchr(lower, '\0') + 1;
1712 sb->s_stack_depth++;
1713 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
1714 pr_err("maximum fs stacking depth exceeded\n");
1718 err = ovl_get_layers(sb, ofs, stack, numlower, layers);
1723 oe = ovl_alloc_entry(numlower);
1727 for (i = 0; i < numlower; i++) {
1728 oe->lowerstack[i].dentry = dget(stack[i].dentry);
1729 oe->lowerstack[i].layer = &ofs->layers[i+1];
1733 for (i = 0; i < numlower; i++)
1734 path_put(&stack[i]);
1745 * Check if this layer root is a descendant of:
1746 * - another layer of this overlayfs instance
1747 * - upper/work dir of any overlayfs instance
1749 static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs,
1750 struct dentry *dentry, const char *name)
1752 struct dentry *next = dentry, *parent;
1758 parent = dget_parent(next);
1760 /* Walk back ancestors to root (inclusive) looking for traps */
1761 while (!err && parent != next) {
1762 if (ovl_lookup_trap_inode(sb, parent)) {
1764 pr_err("overlapping %s path\n", name);
1765 } else if (ovl_is_inuse(parent)) {
1766 err = ovl_report_in_use(ofs, name);
1769 parent = dget_parent(next);
1779 * Check if any of the layers or work dirs overlap.
1781 static int ovl_check_overlapping_layers(struct super_block *sb,
1786 if (ovl_upper_mnt(ofs)) {
1787 err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root,
1793 * Checking workbasedir avoids hitting ovl_is_inuse(parent) of
1794 * this instance and covers overlapping work and index dirs,
1795 * unless work or index dir have been moved since created inside
1796 * workbasedir. In that case, we already have their traps in
1797 * inode cache and we will catch that case on lookup.
1799 err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir");
1804 for (i = 1; i < ofs->numlayer; i++) {
1805 err = ovl_check_layer(sb, ofs,
1806 ofs->layers[i].mnt->mnt_root,
1815 static struct dentry *ovl_get_root(struct super_block *sb,
1816 struct dentry *upperdentry,
1817 struct ovl_entry *oe)
1819 struct dentry *root;
1820 struct ovl_path *lowerpath = &oe->lowerstack[0];
1821 unsigned long ino = d_inode(lowerpath->dentry)->i_ino;
1822 int fsid = lowerpath->layer->fsid;
1823 struct ovl_inode_params oip = {
1824 .upperdentry = upperdentry,
1825 .lowerpath = lowerpath,
1828 root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
1832 root->d_fsdata = oe;
1835 /* Root inode uses upper st_ino/i_ino */
1836 ino = d_inode(upperdentry)->i_ino;
1838 ovl_dentry_set_upper_alias(root);
1839 if (ovl_is_impuredir(sb, upperdentry))
1840 ovl_set_flag(OVL_IMPURE, d_inode(root));
1843 /* Root is always merge -> can have whiteouts */
1844 ovl_set_flag(OVL_WHITEOUTS, d_inode(root));
1845 ovl_dentry_set_flag(OVL_E_CONNECTED, root);
1846 ovl_set_upperdata(d_inode(root));
1847 ovl_inode_init(d_inode(root), &oip, ino, fsid);
1848 ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE);
1853 static int ovl_fill_super(struct super_block *sb, void *data, int silent)
1855 struct path upperpath = { };
1856 struct dentry *root_dentry;
1857 struct ovl_entry *oe;
1859 struct ovl_layer *layers;
1861 char *splitlower = NULL;
1862 unsigned int numlower;
1865 sb->s_d_op = &ovl_dentry_operations;
1868 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
1872 ofs->creator_cred = cred = prepare_creds();
1876 /* Is there a reason anyone would want not to share whiteouts? */
1877 ofs->share_whiteout = true;
1879 ofs->config.index = ovl_index_def;
1880 ofs->config.nfs_export = ovl_nfs_export_def;
1881 ofs->config.xino = ovl_xino_def();
1882 ofs->config.metacopy = ovl_metacopy_def;
1883 err = ovl_parse_opt((char *) data, &ofs->config);
1888 if (!ofs->config.lowerdir) {
1890 pr_err("missing 'lowerdir'\n");
1895 splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
1899 numlower = ovl_split_lowerdirs(splitlower);
1900 if (numlower > OVL_MAX_STACK) {
1901 pr_err("too many lower directories, limit is %d\n",
1906 layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL);
1910 ofs->layers = layers;
1911 /* Layer 0 is reserved for upper even if there's no upper */
1914 sb->s_stack_depth = 0;
1915 sb->s_maxbytes = MAX_LFS_FILESIZE;
1916 atomic_long_set(&ofs->last_ino, 1);
1917 /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
1918 if (ofs->config.xino != OVL_XINO_OFF) {
1919 ofs->xino_mode = BITS_PER_LONG - 32;
1920 if (!ofs->xino_mode) {
1921 pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n");
1922 ofs->config.xino = OVL_XINO_OFF;
1926 /* alloc/destroy_inode needed for setting up traps in inode cache */
1927 sb->s_op = &ovl_super_operations;
1929 if (ofs->config.upperdir) {
1930 if (!ofs->config.workdir) {
1931 pr_err("missing 'workdir'\n");
1935 err = ovl_get_upper(sb, ofs, &layers[0], &upperpath);
1939 err = ovl_get_workdir(sb, ofs, &upperpath);
1944 sb->s_flags |= SB_RDONLY;
1946 sb->s_stack_depth = ovl_upper_mnt(ofs)->mnt_sb->s_stack_depth;
1947 sb->s_time_gran = ovl_upper_mnt(ofs)->mnt_sb->s_time_gran;
1950 oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers);
1955 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1956 if (!ovl_upper_mnt(ofs))
1957 sb->s_flags |= SB_RDONLY;
1959 if (!ovl_force_readonly(ofs) && ofs->config.index) {
1960 err = ovl_get_indexdir(sb, ofs, oe, &upperpath);
1964 /* Force r/o mount with no index dir */
1966 sb->s_flags |= SB_RDONLY;
1969 err = ovl_check_overlapping_layers(sb, ofs);
1973 /* Show index=off in /proc/mounts for forced r/o mount */
1974 if (!ofs->indexdir) {
1975 ofs->config.index = false;
1976 if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) {
1977 pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n");
1978 ofs->config.nfs_export = false;
1982 if (ofs->config.metacopy && ofs->config.nfs_export) {
1983 pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
1984 ofs->config.nfs_export = false;
1987 if (ofs->config.nfs_export)
1988 sb->s_export_op = &ovl_export_operations;
1990 /* Never override disk quota limits or use reserved space */
1991 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
1993 sb->s_magic = OVERLAYFS_SUPER_MAGIC;
1994 sb->s_xattr = ovl_xattr_handlers;
1995 sb->s_fs_info = ofs;
1996 sb->s_flags |= SB_POSIXACL;
1997 sb->s_iflags |= SB_I_SKIP_SYNC;
2000 root_dentry = ovl_get_root(sb, upperpath.dentry, oe);
2004 mntput(upperpath.mnt);
2007 sb->s_root = root_dentry;
2012 ovl_entry_stack_free(oe);
2016 path_put(&upperpath);
2022 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
2023 const char *dev_name, void *raw_data)
2025 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
2028 static struct file_system_type ovl_fs_type = {
2029 .owner = THIS_MODULE,
2032 .kill_sb = kill_anon_super,
2034 MODULE_ALIAS_FS("overlay");
2036 static void ovl_inode_init_once(void *foo)
2038 struct ovl_inode *oi = foo;
2040 inode_init_once(&oi->vfs_inode);
2043 static int __init ovl_init(void)
2047 ovl_inode_cachep = kmem_cache_create("ovl_inode",
2048 sizeof(struct ovl_inode), 0,
2049 (SLAB_RECLAIM_ACCOUNT|
2050 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
2051 ovl_inode_init_once);
2052 if (ovl_inode_cachep == NULL)
2055 err = ovl_aio_request_cache_init();
2057 err = register_filesystem(&ovl_fs_type);
2061 ovl_aio_request_cache_destroy();
2063 kmem_cache_destroy(ovl_inode_cachep);
2068 static void __exit ovl_exit(void)
2070 unregister_filesystem(&ovl_fs_type);
2073 * Make sure all delayed rcu free inodes are flushed before we
2077 kmem_cache_destroy(ovl_inode_cachep);
2078 ovl_aio_request_cache_destroy();
2081 module_init(ovl_init);
2082 module_exit(ovl_exit);