v4.19.13 snapshot.
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
new file mode 100644
index 0000000..0fb0a59
--- /dev/null
+++ b/fs/overlayfs/super.c
@@ -0,0 +1,1591 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <uapi/linux/magic.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/mount.h>
+#include <linux/parser.h>
+#include <linux/module.h>
+#include <linux/statfs.h>
+#include <linux/seq_file.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/exportfs.h>
+#include "overlayfs.h"
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
+MODULE_DESCRIPTION("Overlay filesystem");
+MODULE_LICENSE("GPL");
+
+
+struct ovl_dir_cache;
+
+#define OVL_MAX_STACK 500
+
+static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
+module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
+MODULE_PARM_DESC(ovl_redirect_dir_def,
+ "Default to on or off for the redirect_dir feature");
+
+static bool ovl_redirect_always_follow =
+ IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
+module_param_named(redirect_always_follow, ovl_redirect_always_follow,
+ bool, 0644);
+MODULE_PARM_DESC(ovl_redirect_always_follow,
+ "Follow redirects even if redirect_dir feature is turned off");
+
+static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
+module_param_named(index, ovl_index_def, bool, 0644);
+MODULE_PARM_DESC(ovl_index_def,
+ "Default to on or off for the inodes index feature");
+
+static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
+module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
+MODULE_PARM_DESC(ovl_nfs_export_def,
+ "Default to on or off for the NFS export feature");
+
+static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
+module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
+MODULE_PARM_DESC(ovl_xino_auto_def,
+ "Auto enable xino feature");
+
+static void ovl_entry_stack_free(struct ovl_entry *oe)
+{
+ unsigned int i;
+
+ for (i = 0; i < oe->numlower; i++)
+ dput(oe->lowerstack[i].dentry);
+}
+
+static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
+module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
+MODULE_PARM_DESC(ovl_metacopy_def,
+ "Default to on or off for the metadata only copy up feature");
+
+static void ovl_dentry_release(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe) {
+ ovl_entry_stack_free(oe);
+ kfree_rcu(oe, rcu);
+ }
+}
+
+static struct dentry *ovl_d_real(struct dentry *dentry,
+ const struct inode *inode)
+{
+ struct dentry *real;
+
+ /* It's an overlay file */
+ if (inode && d_inode(dentry) == inode)
+ return dentry;
+
+ if (!d_is_reg(dentry)) {
+ if (!inode || inode == d_inode(dentry))
+ return dentry;
+ goto bug;
+ }
+
+ real = ovl_dentry_upper(dentry);
+ if (real && (inode == d_inode(real)))
+ return real;
+
+ if (real && !inode && ovl_has_upperdata(d_inode(dentry)))
+ return real;
+
+ real = ovl_dentry_lowerdata(dentry);
+ if (!real)
+ goto bug;
+
+ /* Handle recursion */
+ real = d_real(real, inode);
+
+ if (!inode || inode == d_inode(real))
+ return real;
+bug:
+ WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry,
+ inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
+ return dentry;
+}
+
+static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ unsigned int i;
+ int ret = 1;
+
+ for (i = 0; i < oe->numlower; i++) {
+ struct dentry *d = oe->lowerstack[i].dentry;
+
+ if (d->d_flags & DCACHE_OP_REVALIDATE) {
+ ret = d->d_op->d_revalidate(d, flags);
+ if (ret < 0)
+ return ret;
+ if (!ret) {
+ if (!(flags & LOOKUP_RCU))
+ d_invalidate(d);
+ return -ESTALE;
+ }
+ }
+ }
+ return 1;
+}
+
+static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ unsigned int i;
+ int ret = 1;
+
+ for (i = 0; i < oe->numlower; i++) {
+ struct dentry *d = oe->lowerstack[i].dentry;
+
+ if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
+ ret = d->d_op->d_weak_revalidate(d, flags);
+ if (ret <= 0)
+ break;
+ }
+ }
+ return ret;
+}
+
+static const struct dentry_operations ovl_dentry_operations = {
+ .d_release = ovl_dentry_release,
+ .d_real = ovl_d_real,
+};
+
+static const struct dentry_operations ovl_reval_dentry_operations = {
+ .d_release = ovl_dentry_release,
+ .d_real = ovl_d_real,
+ .d_revalidate = ovl_dentry_revalidate,
+ .d_weak_revalidate = ovl_dentry_weak_revalidate,
+};
+
+static struct kmem_cache *ovl_inode_cachep;
+
+static struct inode *ovl_alloc_inode(struct super_block *sb)
+{
+ struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
+
+ if (!oi)
+ return NULL;
+
+ oi->cache = NULL;
+ oi->redirect = NULL;
+ oi->version = 0;
+ oi->flags = 0;
+ oi->__upperdentry = NULL;
+ oi->lower = NULL;
+ oi->lowerdata = NULL;
+ mutex_init(&oi->lock);
+
+ return &oi->vfs_inode;
+}
+
+static void ovl_i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+
+ kmem_cache_free(ovl_inode_cachep, OVL_I(inode));
+}
+
+static void ovl_destroy_inode(struct inode *inode)
+{
+ struct ovl_inode *oi = OVL_I(inode);
+
+ dput(oi->__upperdentry);
+ iput(oi->lower);
+ if (S_ISDIR(inode->i_mode))
+ ovl_dir_cache_free(inode);
+ else
+ iput(oi->lowerdata);
+ kfree(oi->redirect);
+ mutex_destroy(&oi->lock);
+
+ call_rcu(&inode->i_rcu, ovl_i_callback);
+}
+
+static void ovl_free_fs(struct ovl_fs *ofs)
+{
+ unsigned i;
+
+ dput(ofs->indexdir);
+ dput(ofs->workdir);
+ if (ofs->workdir_locked)
+ ovl_inuse_unlock(ofs->workbasedir);
+ dput(ofs->workbasedir);
+ if (ofs->upperdir_locked)
+ ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
+ mntput(ofs->upper_mnt);
+ for (i = 0; i < ofs->numlower; i++)
+ mntput(ofs->lower_layers[i].mnt);
+ for (i = 0; i < ofs->numlowerfs; i++)
+ free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
+ kfree(ofs->lower_layers);
+ kfree(ofs->lower_fs);
+
+ kfree(ofs->config.lowerdir);
+ kfree(ofs->config.upperdir);
+ kfree(ofs->config.workdir);
+ kfree(ofs->config.redirect_mode);
+ if (ofs->creator_cred)
+ put_cred(ofs->creator_cred);
+ kfree(ofs);
+}
+
+static void ovl_put_super(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ ovl_free_fs(ofs);
+}
+
+/* Sync real dirty inodes in upper filesystem (if it exists) */
+static int ovl_sync_fs(struct super_block *sb, int wait)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct super_block *upper_sb;
+ int ret;
+
+ if (!ofs->upper_mnt)
+ return 0;
+
+ /*
+ * If this is a sync(2) call or an emergency sync, all the super blocks
+ * will be iterated, including upper_sb, so no need to do anything.
+ *
+ * If this is a syncfs(2) call, then we do need to call
+ * sync_filesystem() on upper_sb, but enough if we do it when being
+ * called with wait == 1.
+ */
+ if (!wait)
+ return 0;
+
+ upper_sb = ofs->upper_mnt->mnt_sb;
+
+ down_read(&upper_sb->s_umount);
+ ret = sync_filesystem(upper_sb);
+ up_read(&upper_sb->s_umount);
+
+ return ret;
+}
+
+/**
+ * ovl_statfs
+ * @sb: The overlayfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. As writes always target the upper layer
+ * filesystem pass the statfs to the upper filesystem (if it exists)
+ */
+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct path path;
+ int err;
+
+ ovl_path_real(root_dentry, &path);
+
+ err = vfs_statfs(&path, buf);
+ if (!err) {
+ buf->f_namelen = ofs->namelen;
+ buf->f_type = OVERLAYFS_SUPER_MAGIC;
+ }
+
+ return err;
+}
+
+/* Will this overlay be forced to mount/remount ro? */
+static bool ovl_force_readonly(struct ovl_fs *ofs)
+{
+ return (!ofs->upper_mnt || !ofs->workdir);
+}
+
+static const char *ovl_redirect_mode_def(void)
+{
+ return ovl_redirect_dir_def ? "on" : "off";
+}
+
+enum {
+ OVL_XINO_OFF,
+ OVL_XINO_AUTO,
+ OVL_XINO_ON,
+};
+
+static const char * const ovl_xino_str[] = {
+ "off",
+ "auto",
+ "on",
+};
+
+static inline int ovl_xino_def(void)
+{
+ return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
+}
+
+/**
+ * ovl_show_options
+ *
+ * Prints the mount options for a given superblock.
+ * Returns zero; does not fail.
+ */
+static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
+{
+ struct super_block *sb = dentry->d_sb;
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ seq_show_option(m, "lowerdir", ofs->config.lowerdir);
+ if (ofs->config.upperdir) {
+ seq_show_option(m, "upperdir", ofs->config.upperdir);
+ seq_show_option(m, "workdir", ofs->config.workdir);
+ }
+ if (ofs->config.default_permissions)
+ seq_puts(m, ",default_permissions");
+ if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0)
+ seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode);
+ if (ofs->config.index != ovl_index_def)
+ seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
+ if (ofs->config.nfs_export != ovl_nfs_export_def)
+ seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
+ "on" : "off");
+ if (ofs->config.xino != ovl_xino_def())
+ seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
+ if (ofs->config.metacopy != ovl_metacopy_def)
+ seq_printf(m, ",metacopy=%s",
+ ofs->config.metacopy ? "on" : "off");
+ return 0;
+}
+
+static int ovl_remount(struct super_block *sb, int *flags, char *data)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
+ return -EROFS;
+
+ return 0;
+}
+
+static const struct super_operations ovl_super_operations = {
+ .alloc_inode = ovl_alloc_inode,
+ .destroy_inode = ovl_destroy_inode,
+ .drop_inode = generic_delete_inode,
+ .put_super = ovl_put_super,
+ .sync_fs = ovl_sync_fs,
+ .statfs = ovl_statfs,
+ .show_options = ovl_show_options,
+ .remount_fs = ovl_remount,
+};
+
+enum {
+ OPT_LOWERDIR,
+ OPT_UPPERDIR,
+ OPT_WORKDIR,
+ OPT_DEFAULT_PERMISSIONS,
+ OPT_REDIRECT_DIR,
+ OPT_INDEX_ON,
+ OPT_INDEX_OFF,
+ OPT_NFS_EXPORT_ON,
+ OPT_NFS_EXPORT_OFF,
+ OPT_XINO_ON,
+ OPT_XINO_OFF,
+ OPT_XINO_AUTO,
+ OPT_METACOPY_ON,
+ OPT_METACOPY_OFF,
+ OPT_ERR,
+};
+
+static const match_table_t ovl_tokens = {
+ {OPT_LOWERDIR, "lowerdir=%s"},
+ {OPT_UPPERDIR, "upperdir=%s"},
+ {OPT_WORKDIR, "workdir=%s"},
+ {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
+ {OPT_REDIRECT_DIR, "redirect_dir=%s"},
+ {OPT_INDEX_ON, "index=on"},
+ {OPT_INDEX_OFF, "index=off"},
+ {OPT_NFS_EXPORT_ON, "nfs_export=on"},
+ {OPT_NFS_EXPORT_OFF, "nfs_export=off"},
+ {OPT_XINO_ON, "xino=on"},
+ {OPT_XINO_OFF, "xino=off"},
+ {OPT_XINO_AUTO, "xino=auto"},
+ {OPT_METACOPY_ON, "metacopy=on"},
+ {OPT_METACOPY_OFF, "metacopy=off"},
+ {OPT_ERR, NULL}
+};
+
+static char *ovl_next_opt(char **s)
+{
+ char *sbegin = *s;
+ char *p;
+
+ if (sbegin == NULL)
+ return NULL;
+
+ for (p = sbegin; *p; p++) {
+ if (*p == '\\') {
+ p++;
+ if (!*p)
+ break;
+ } else if (*p == ',') {
+ *p = '\0';
+ *s = p + 1;
+ return sbegin;
+ }
+ }
+ *s = NULL;
+ return sbegin;
+}
+
+static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
+{
+ if (strcmp(mode, "on") == 0) {
+ config->redirect_dir = true;
+ /*
+ * Does not make sense to have redirect creation without
+ * redirect following.
+ */
+ config->redirect_follow = true;
+ } else if (strcmp(mode, "follow") == 0) {
+ config->redirect_follow = true;
+ } else if (strcmp(mode, "off") == 0) {
+ if (ovl_redirect_always_follow)
+ config->redirect_follow = true;
+ } else if (strcmp(mode, "nofollow") != 0) {
+ pr_err("overlayfs: bad mount option \"redirect_dir=%s\"\n",
+ mode);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int ovl_parse_opt(char *opt, struct ovl_config *config)
+{
+ char *p;
+ int err;
+ bool metacopy_opt = false, redirect_opt = false;
+
+ config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
+ if (!config->redirect_mode)
+ return -ENOMEM;
+
+ while ((p = ovl_next_opt(&opt)) != NULL) {
+ int token;
+ substring_t args[MAX_OPT_ARGS];
+
+ if (!*p)
+ continue;
+
+ token = match_token(p, ovl_tokens, args);
+ switch (token) {
+ case OPT_UPPERDIR:
+ kfree(config->upperdir);
+ config->upperdir = match_strdup(&args[0]);
+ if (!config->upperdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_LOWERDIR:
+ kfree(config->lowerdir);
+ config->lowerdir = match_strdup(&args[0]);
+ if (!config->lowerdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_WORKDIR:
+ kfree(config->workdir);
+ config->workdir = match_strdup(&args[0]);
+ if (!config->workdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_DEFAULT_PERMISSIONS:
+ config->default_permissions = true;
+ break;
+
+ case OPT_REDIRECT_DIR:
+ kfree(config->redirect_mode);
+ config->redirect_mode = match_strdup(&args[0]);
+ if (!config->redirect_mode)
+ return -ENOMEM;
+ redirect_opt = true;
+ break;
+
+ case OPT_INDEX_ON:
+ config->index = true;
+ break;
+
+ case OPT_INDEX_OFF:
+ config->index = false;
+ break;
+
+ case OPT_NFS_EXPORT_ON:
+ config->nfs_export = true;
+ break;
+
+ case OPT_NFS_EXPORT_OFF:
+ config->nfs_export = false;
+ break;
+
+ case OPT_XINO_ON:
+ config->xino = OVL_XINO_ON;
+ break;
+
+ case OPT_XINO_OFF:
+ config->xino = OVL_XINO_OFF;
+ break;
+
+ case OPT_XINO_AUTO:
+ config->xino = OVL_XINO_AUTO;
+ break;
+
+ case OPT_METACOPY_ON:
+ config->metacopy = true;
+ metacopy_opt = true;
+ break;
+
+ case OPT_METACOPY_OFF:
+ config->metacopy = false;
+ break;
+
+ default:
+ pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
+ return -EINVAL;
+ }
+ }
+
+ /* Workdir is useless in non-upper mount */
+ if (!config->upperdir && config->workdir) {
+ pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
+ config->workdir);
+ kfree(config->workdir);
+ config->workdir = NULL;
+ }
+
+ err = ovl_parse_redirect_mode(config, config->redirect_mode);
+ if (err)
+ return err;
+
+ /*
+ * This is to make the logic below simpler. It doesn't make any other
+ * difference, since config->redirect_dir is only used for upper.
+ */
+ if (!config->upperdir && config->redirect_follow)
+ config->redirect_dir = true;
+
+ /* Resolve metacopy -> redirect_dir dependency */
+ if (config->metacopy && !config->redirect_dir) {
+ if (metacopy_opt && redirect_opt) {
+ pr_err("overlayfs: conflicting options: metacopy=on,redirect_dir=%s\n",
+ config->redirect_mode);
+ return -EINVAL;
+ }
+ if (redirect_opt) {
+ /*
+ * There was an explicit redirect_dir=... that resulted
+ * in this conflict.
+ */
+ pr_info("overlayfs: disabling metacopy due to redirect_dir=%s\n",
+ config->redirect_mode);
+ config->metacopy = false;
+ } else {
+ /* Automatically enable redirect otherwise. */
+ config->redirect_follow = config->redirect_dir = true;
+ }
+ }
+
+ return 0;
+}
+
+#define OVL_WORKDIR_NAME "work"
+#define OVL_INDEXDIR_NAME "index"
+
+static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
+ const char *name, bool persist)
+{
+ struct inode *dir = ofs->workbasedir->d_inode;
+ struct vfsmount *mnt = ofs->upper_mnt;
+ struct dentry *work;
+ int err;
+ bool retried = false;
+ bool locked = false;
+
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ locked = true;
+
+retry:
+ work = lookup_one_len(name, ofs->workbasedir, strlen(name));
+
+ if (!IS_ERR(work)) {
+ struct iattr attr = {
+ .ia_valid = ATTR_MODE,
+ .ia_mode = S_IFDIR | 0,
+ };
+
+ if (work->d_inode) {
+ err = -EEXIST;
+ if (retried)
+ goto out_dput;
+
+ if (persist)
+ goto out_unlock;
+
+ retried = true;
+ ovl_workdir_cleanup(dir, mnt, work, 0);
+ dput(work);
+ goto retry;
+ }
+
+ work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode));
+ err = PTR_ERR(work);
+ if (IS_ERR(work))
+ goto out_err;
+
+ /*
+ * Try to remove POSIX ACL xattrs from workdir. We are good if:
+ *
+ * a) success (there was a POSIX ACL xattr and was removed)
+ * b) -ENODATA (there was no POSIX ACL xattr)
+ * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
+ *
+ * There are various other error values that could effectively
+ * mean that the xattr doesn't exist (e.g. -ERANGE is returned
+ * if the xattr name is too long), but the set of filesystems
+ * allowed as upper are limited to "normal" ones, where checking
+ * for the above two errors is sufficient.
+ */
+ err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
+ if (err && err != -ENODATA && err != -EOPNOTSUPP)
+ goto out_dput;
+
+ err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
+ if (err && err != -ENODATA && err != -EOPNOTSUPP)
+ goto out_dput;
+
+ /* Clear any inherited mode bits */
+ inode_lock(work->d_inode);
+ err = notify_change(work, &attr, NULL);
+ inode_unlock(work->d_inode);
+ if (err)
+ goto out_dput;
+ } else {
+ err = PTR_ERR(work);
+ goto out_err;
+ }
+out_unlock:
+ if (locked)
+ inode_unlock(dir);
+
+ return work;
+
+out_dput:
+ dput(work);
+out_err:
+ pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
+ ofs->config.workdir, name, -err);
+ work = NULL;
+ goto out_unlock;
+}
+
+static void ovl_unescape(char *s)
+{
+ char *d = s;
+
+ for (;; s++, d++) {
+ if (*s == '\\')
+ s++;
+ *d = *s;
+ if (!*s)
+ break;
+ }
+}
+
+static int ovl_mount_dir_noesc(const char *name, struct path *path)
+{
+ int err = -EINVAL;
+
+ if (!*name) {
+ pr_err("overlayfs: empty lowerdir\n");
+ goto out;
+ }
+ err = kern_path(name, LOOKUP_FOLLOW, path);
+ if (err) {
+ pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
+ goto out;
+ }
+ err = -EINVAL;
+ if (ovl_dentry_weird(path->dentry)) {
+ pr_err("overlayfs: filesystem on '%s' not supported\n", name);
+ goto out_put;
+ }
+ if (!d_is_dir(path->dentry)) {
+ pr_err("overlayfs: '%s' not a directory\n", name);
+ goto out_put;
+ }
+ return 0;
+
+out_put:
+ path_put_init(path);
+out:
+ return err;
+}
+
+static int ovl_mount_dir(const char *name, struct path *path)
+{
+ int err = -ENOMEM;
+ char *tmp = kstrdup(name, GFP_KERNEL);
+
+ if (tmp) {
+ ovl_unescape(tmp);
+ err = ovl_mount_dir_noesc(tmp, path);
+
+ if (!err)
+ if (ovl_dentry_remote(path->dentry)) {
+ pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
+ tmp);
+ path_put_init(path);
+ err = -EINVAL;
+ }
+ kfree(tmp);
+ }
+ return err;
+}
+
+static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
+ const char *name)
+{
+ struct kstatfs statfs;
+ int err = vfs_statfs(path, &statfs);
+
+ if (err)
+ pr_err("overlayfs: statfs failed on '%s'\n", name);
+ else
+ ofs->namelen = max(ofs->namelen, statfs.f_namelen);
+
+ return err;
+}
+
+static int ovl_lower_dir(const char *name, struct path *path,
+ struct ovl_fs *ofs, int *stack_depth, bool *remote)
+{
+ int fh_type;
+ int err;
+
+ err = ovl_mount_dir_noesc(name, path);
+ if (err)
+ goto out;
+
+ err = ovl_check_namelen(path, ofs, name);
+ if (err)
+ goto out_put;
+
+ *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
+
+ if (ovl_dentry_remote(path->dentry))
+ *remote = true;
+
+ /*
+ * The inodes index feature and NFS export need to encode and decode
+ * file handles, so they require that all layers support them.
+ */
+ fh_type = ovl_can_decode_fh(path->dentry->d_sb);
+ if ((ofs->config.nfs_export ||
+ (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
+ ofs->config.index = false;
+ ofs->config.nfs_export = false;
+ pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
+ name);
+ }
+
+ /* Check if lower fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
+ return 0;
+
+out_put:
+ path_put_init(path);
+out:
+ return err;
+}
+
+/* Workdir should not be subdir of upperdir and vice versa */
+static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
+{
+ bool ok = false;
+
+ if (workdir != upperdir) {
+ ok = (lock_rename(workdir, upperdir) == NULL);
+ unlock_rename(workdir, upperdir);
+ }
+ return ok;
+}
+
+static unsigned int ovl_split_lowerdirs(char *str)
+{
+ unsigned int ctr = 1;
+ char *s, *d;
+
+ for (s = d = str;; s++, d++) {
+ if (*s == '\\') {
+ s++;
+ } else if (*s == ':') {
+ *d = '\0';
+ ctr++;
+ continue;
+ }
+ *d = *s;
+ if (!*s)
+ break;
+ }
+ return ctr;
+}
+
+static int __maybe_unused
+ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
+}
+
+static int __maybe_unused
+ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *realinode = ovl_inode_real(inode);
+ struct posix_acl *acl = NULL;
+ int err;
+
+ /* Check that everything is OK before copy-up */
+ if (value) {
+ acl = posix_acl_from_xattr(&init_user_ns, value, size);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ }
+ err = -EOPNOTSUPP;
+ if (!IS_POSIXACL(d_inode(workdir)))
+ goto out_acl_release;
+ if (!realinode->i_op->set_acl)
+ goto out_acl_release;
+ if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
+ err = acl ? -EACCES : 0;
+ goto out_acl_release;
+ }
+ err = -EPERM;
+ if (!inode_owner_or_capable(inode))
+ goto out_acl_release;
+
+ posix_acl_release(acl);
+
+ /*
+ * Check if sgid bit needs to be cleared (actual setacl operation will
+ * be done with mounter's capabilities and so that won't do it for us).
+ */
+ if (unlikely(inode->i_mode & S_ISGID) &&
+ handler->flags == ACL_TYPE_ACCESS &&
+ !in_group_p(inode->i_gid) &&
+ !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
+ struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
+
+ err = ovl_setattr(dentry, &iattr);
+ if (err)
+ return err;
+ }
+
+ err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
+ if (!err)
+ ovl_copyattr(ovl_inode_real(inode), inode);
+
+ return err;
+
+out_acl_release:
+ posix_acl_release(acl);
+ return err;
+}
+
+static int ovl_own_xattr_get(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ovl_own_xattr_set(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ovl_other_xattr_get(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ return ovl_xattr_get(dentry, inode, name, buffer, size);
+}
+
+static int ovl_other_xattr_set(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ return ovl_xattr_set(dentry, inode, name, value, size, flags);
+}
+
+static const struct xattr_handler __maybe_unused
+ovl_posix_acl_access_xattr_handler = {
+ .name = XATTR_NAME_POSIX_ACL_ACCESS,
+ .flags = ACL_TYPE_ACCESS,
+ .get = ovl_posix_acl_xattr_get,
+ .set = ovl_posix_acl_xattr_set,
+};
+
+static const struct xattr_handler __maybe_unused
+ovl_posix_acl_default_xattr_handler = {
+ .name = XATTR_NAME_POSIX_ACL_DEFAULT,
+ .flags = ACL_TYPE_DEFAULT,
+ .get = ovl_posix_acl_xattr_get,
+ .set = ovl_posix_acl_xattr_set,
+};
+
+static const struct xattr_handler ovl_own_xattr_handler = {
+ .prefix = OVL_XATTR_PREFIX,
+ .get = ovl_own_xattr_get,
+ .set = ovl_own_xattr_set,
+};
+
+static const struct xattr_handler ovl_other_xattr_handler = {
+ .prefix = "", /* catch all */
+ .get = ovl_other_xattr_get,
+ .set = ovl_other_xattr_set,
+};
+
+static const struct xattr_handler *ovl_xattr_handlers[] = {
+#ifdef CONFIG_FS_POSIX_ACL
+ &ovl_posix_acl_access_xattr_handler,
+ &ovl_posix_acl_default_xattr_handler,
+#endif
+ &ovl_own_xattr_handler,
+ &ovl_other_xattr_handler,
+ NULL
+};
+
+static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)
+{
+ struct vfsmount *upper_mnt;
+ int err;
+
+ err = ovl_mount_dir(ofs->config.upperdir, upperpath);
+ if (err)
+ goto out;
+
+ /* Upper fs should not be r/o */
+ if (sb_rdonly(upperpath->mnt->mnt_sb)) {
+ pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
+ if (err)
+ goto out;
+
+ upper_mnt = clone_private_mount(upperpath);
+ err = PTR_ERR(upper_mnt);
+ if (IS_ERR(upper_mnt)) {
+ pr_err("overlayfs: failed to clone upperpath\n");
+ goto out;
+ }
+
+ /* Don't inherit atime flags */
+ upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
+ ofs->upper_mnt = upper_mnt;
+
+ err = -EBUSY;
+ if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) {
+ ofs->upperdir_locked = true;
+ } else if (ofs->config.index) {
+ pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");
+ goto out;
+ } else {
+ pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
+{
+ struct vfsmount *mnt = ofs->upper_mnt;
+ struct dentry *temp;
+ int fh_type;
+ int err;
+
+ err = mnt_want_write(mnt);
+ if (err)
+ return err;
+
+ ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
+ if (!ofs->workdir)
+ goto out;
+
+ /*
+ * Upper should support d_type, else whiteouts are visible. Given
+ * workdir and upper are on same fs, we can do iterate_dir() on
+ * workdir. This check requires successful creation of workdir in
+ * previous step.
+ */
+ err = ovl_check_d_type_supported(workpath);
+ if (err < 0)
+ goto out;
+
+ /*
+ * We allowed this configuration and don't want to break users over
+ * kernel upgrade. So warn instead of erroring out.
+ */
+ if (!err)
+ pr_warn("overlayfs: upper fs needs to support d_type.\n");
+
+ /* Check if upper/work fs supports O_TMPFILE */
+ temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
+ ofs->tmpfile = !IS_ERR(temp);
+ if (ofs->tmpfile)
+ dput(temp);
+ else
+ pr_warn("overlayfs: upper fs does not support tmpfile.\n");
+
+ /*
+ * Check if upper/work fs supports trusted.overlay.* xattr
+ */
+ err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0);
+ if (err) {
+ ofs->noxattr = true;
+ ofs->config.index = false;
+ ofs->config.metacopy = false;
+ pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
+ err = 0;
+ } else {
+ vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
+ }
+
+ /* Check if upper/work fs supports file handles */
+ fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
+ if (ofs->config.index && !fh_type) {
+ ofs->config.index = false;
+ pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
+ }
+
+ /* Check if upper fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
+ /* NFS export of r/w mount depends on index */
+ if (ofs->config.nfs_export && !ofs->config.index) {
+ pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+out:
+ mnt_drop_write(mnt);
+ return err;
+}
+
+static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
+{
+ int err;
+ struct path workpath = { };
+
+ err = ovl_mount_dir(ofs->config.workdir, &workpath);
+ if (err)
+ goto out;
+
+ err = -EINVAL;
+ if (upperpath->mnt != workpath.mnt) {
+ pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
+ goto out;
+ }
+ if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) {
+ pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
+ goto out;
+ }
+
+ ofs->workbasedir = dget(workpath.dentry);
+
+ err = -EBUSY;
+ if (ovl_inuse_trylock(ofs->workbasedir)) {
+ ofs->workdir_locked = true;
+ } else if (ofs->config.index) {
+ pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n");
+ goto out;
+ } else {
+ pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
+ }
+
+ err = ovl_make_workdir(ofs, &workpath);
+ if (err)
+ goto out;
+
+ err = 0;
+out:
+ path_put(&workpath);
+
+ return err;
+}
+
+static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
+ struct path *upperpath)
+{
+ struct vfsmount *mnt = ofs->upper_mnt;
+ int err;
+
+ err = mnt_want_write(mnt);
+ if (err)
+ return err;
+
+ /* Verify lower root is upper root origin */
+ err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
+ true);
+ if (err) {
+ pr_err("overlayfs: failed to verify upper root origin\n");
+ goto out;
+ }
+
+ ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
+ if (ofs->indexdir) {
+ /*
+ * Verify upper root is exclusively associated with index dir.
+ * Older kernels stored upper fh in "trusted.overlay.origin"
+ * xattr. If that xattr exists, verify that it is a match to
+ * upper dir file handle. In any case, verify or set xattr
+ * "trusted.overlay.upper" to indicate that index may have
+ * directory entries.
+ */
+ if (ovl_check_origin_xattr(ofs->indexdir)) {
+ err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN,
+ upperpath->dentry, true, false);
+ if (err)
+ pr_err("overlayfs: failed to verify index dir 'origin' xattr\n");
+ }
+ err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true);
+ if (err)
+ pr_err("overlayfs: failed to verify index dir 'upper' xattr\n");
+
+ /* Cleanup bad/stale/orphan index entries */
+ if (!err)
+ err = ovl_indexdir_cleanup(ofs);
+ }
+ if (err || !ofs->indexdir)
+ pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
+
+out:
+ mnt_drop_write(mnt);
+ return err;
+}
+
+/* Get a unique fsid for the layer */
+static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb)
+{
+ unsigned int i;
+ dev_t dev;
+ int err;
+
+ /* fsid 0 is reserved for upper fs even with non upper overlay */
+ if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb)
+ return 0;
+
+ for (i = 0; i < ofs->numlowerfs; i++) {
+ if (ofs->lower_fs[i].sb == sb)
+ return i + 1;
+ }
+
+ err = get_anon_bdev(&dev);
+ if (err) {
+ pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
+ return err;
+ }
+
+ ofs->lower_fs[ofs->numlowerfs].sb = sb;
+ ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev;
+ ofs->numlowerfs++;
+
+ return ofs->numlowerfs;
+}
+
+static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack,
+ unsigned int numlower)
+{
+ int err;
+ unsigned int i;
+
+ err = -ENOMEM;
+ ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer),
+ GFP_KERNEL);
+ if (ofs->lower_layers == NULL)
+ goto out;
+
+ ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
+ GFP_KERNEL);
+ if (ofs->lower_fs == NULL)
+ goto out;
+
+ for (i = 0; i < numlower; i++) {
+ struct vfsmount *mnt;
+ int fsid;
+
+ err = fsid = ovl_get_fsid(ofs, stack[i].mnt->mnt_sb);
+ if (err < 0)
+ goto out;
+
+ mnt = clone_private_mount(&stack[i]);
+ err = PTR_ERR(mnt);
+ if (IS_ERR(mnt)) {
+ pr_err("overlayfs: failed to clone lowerpath\n");
+ goto out;
+ }
+
+ /*
+ * Make lower layers R/O. That way fchmod/fchown on lower file
+ * will fail instead of modifying lower fs.
+ */
+ mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
+
+ ofs->lower_layers[ofs->numlower].mnt = mnt;
+ ofs->lower_layers[ofs->numlower].idx = i + 1;
+ ofs->lower_layers[ofs->numlower].fsid = fsid;
+ if (fsid) {
+ ofs->lower_layers[ofs->numlower].fs =
+ &ofs->lower_fs[fsid - 1];
+ }
+ ofs->numlower++;
+ }
+
+ /*
+ * When all layers on same fs, overlay can use real inode numbers.
+ * With mount option "xino=on", mounter declares that there are enough
+ * free high bits in underlying fs to hold the unique fsid.
+ * If overlayfs does encounter underlying inodes using the high xino
+ * bits reserved for fsid, it emits a warning and uses the original
+ * inode number.
+ */
+ if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
+ ofs->xino_bits = 0;
+ ofs->config.xino = OVL_XINO_OFF;
+ } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) {
+ /*
+ * This is a roundup of number of bits needed for numlowerfs+1
+ * (i.e. ilog2(numlowerfs+1 - 1) + 1). fsid 0 is reserved for
+ * upper fs even with non upper overlay.
+ */
+ BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31);
+ ofs->xino_bits = ilog2(ofs->numlowerfs) + 1;
+ }
+
+ if (ofs->xino_bits) {
+ pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n",
+ ofs->xino_bits);
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
+ struct ovl_fs *ofs)
+{
+ int err;
+ char *lowertmp, *lower;
+ struct path *stack = NULL;
+ unsigned int stacklen, numlower = 0, i;
+ bool remote = false;
+ struct ovl_entry *oe;
+
+ err = -ENOMEM;
+ lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
+ if (!lowertmp)
+ goto out_err;
+
+ err = -EINVAL;
+ stacklen = ovl_split_lowerdirs(lowertmp);
+ if (stacklen > OVL_MAX_STACK) {
+ pr_err("overlayfs: too many lower directories, limit is %d\n",
+ OVL_MAX_STACK);
+ goto out_err;
+ } else if (!ofs->config.upperdir && stacklen == 1) {
+ pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
+ goto out_err;
+ } else if (!ofs->config.upperdir && ofs->config.nfs_export &&
+ ofs->config.redirect_follow) {
+ pr_warn("overlayfs: NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+
+ err = -ENOMEM;
+ stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
+ if (!stack)
+ goto out_err;
+
+ err = -EINVAL;
+ lower = lowertmp;
+ for (numlower = 0; numlower < stacklen; numlower++) {
+ err = ovl_lower_dir(lower, &stack[numlower], ofs,
+ &sb->s_stack_depth, &remote);
+ if (err)
+ goto out_err;
+
+ lower = strchr(lower, '\0') + 1;
+ }
+
+ err = -EINVAL;
+ sb->s_stack_depth++;
+ if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
+ pr_err("overlayfs: maximum fs stacking depth exceeded\n");
+ goto out_err;
+ }
+
+ err = ovl_get_lower_layers(ofs, stack, numlower);
+ if (err)
+ goto out_err;
+
+ err = -ENOMEM;
+ oe = ovl_alloc_entry(numlower);
+ if (!oe)
+ goto out_err;
+
+ for (i = 0; i < numlower; i++) {
+ oe->lowerstack[i].dentry = dget(stack[i].dentry);
+ oe->lowerstack[i].layer = &ofs->lower_layers[i];
+ }
+
+ if (remote)
+ sb->s_d_op = &ovl_reval_dentry_operations;
+ else
+ sb->s_d_op = &ovl_dentry_operations;
+
+out:
+ for (i = 0; i < numlower; i++)
+ path_put(&stack[i]);
+ kfree(stack);
+ kfree(lowertmp);
+
+ return oe;
+
+out_err:
+ oe = ERR_PTR(err);
+ goto out;
+}
+
+static int ovl_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct path upperpath = { };
+ struct dentry *root_dentry;
+ struct ovl_entry *oe;
+ struct ovl_fs *ofs;
+ struct cred *cred;
+ int err;
+
+ err = -ENOMEM;
+ ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
+ if (!ofs)
+ goto out;
+
+ ofs->creator_cred = cred = prepare_creds();
+ if (!cred)
+ goto out_err;
+
+ ofs->config.index = ovl_index_def;
+ ofs->config.nfs_export = ovl_nfs_export_def;
+ ofs->config.xino = ovl_xino_def();
+ ofs->config.metacopy = ovl_metacopy_def;
+ err = ovl_parse_opt((char *) data, &ofs->config);
+ if (err)
+ goto out_err;
+
+ err = -EINVAL;
+ if (!ofs->config.lowerdir) {
+ if (!silent)
+ pr_err("overlayfs: missing 'lowerdir'\n");
+ goto out_err;
+ }
+
+ sb->s_stack_depth = 0;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
+ /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
+ if (ofs->config.xino != OVL_XINO_OFF)
+ ofs->xino_bits = BITS_PER_LONG - 32;
+
+ if (ofs->config.upperdir) {
+ if (!ofs->config.workdir) {
+ pr_err("overlayfs: missing 'workdir'\n");
+ goto out_err;
+ }
+
+ err = ovl_get_upper(ofs, &upperpath);
+ if (err)
+ goto out_err;
+
+ err = ovl_get_workdir(ofs, &upperpath);
+ if (err)
+ goto out_err;
+
+ if (!ofs->workdir)
+ sb->s_flags |= SB_RDONLY;
+
+ sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth;
+ sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran;
+
+ }
+ oe = ovl_get_lowerstack(sb, ofs);
+ err = PTR_ERR(oe);
+ if (IS_ERR(oe))
+ goto out_err;
+
+ /* If the upper fs is nonexistent, we mark overlayfs r/o too */
+ if (!ofs->upper_mnt)
+ sb->s_flags |= SB_RDONLY;
+
+ if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
+ err = ovl_get_indexdir(ofs, oe, &upperpath);
+ if (err)
+ goto out_free_oe;
+
+ /* Force r/o mount with no index dir */
+ if (!ofs->indexdir) {
+ dput(ofs->workdir);
+ ofs->workdir = NULL;
+ sb->s_flags |= SB_RDONLY;
+ }
+
+ }
+
+ /* Show index=off in /proc/mounts for forced r/o mount */
+ if (!ofs->indexdir) {
+ ofs->config.index = false;
+ if (ofs->upper_mnt && ofs->config.nfs_export) {
+ pr_warn("overlayfs: NFS export requires an index dir, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+ }
+
+ if (ofs->config.metacopy && ofs->config.nfs_export) {
+ pr_warn("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+
+ if (ofs->config.nfs_export)
+ sb->s_export_op = &ovl_export_operations;
+
+ /* Never override disk quota limits or use reserved space */
+ cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
+
+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
+ sb->s_op = &ovl_super_operations;
+ sb->s_xattr = ovl_xattr_handlers;
+ sb->s_fs_info = ofs;
+ sb->s_flags |= SB_POSIXACL;
+
+ err = -ENOMEM;
+ root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
+ if (!root_dentry)
+ goto out_free_oe;
+
+ root_dentry->d_fsdata = oe;
+
+ mntput(upperpath.mnt);
+ if (upperpath.dentry) {
+ ovl_dentry_set_upper_alias(root_dentry);
+ if (ovl_is_impuredir(upperpath.dentry))
+ ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));
+ }
+
+ /* Root is always merge -> can have whiteouts */
+ ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
+ ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
+ ovl_set_upperdata(d_inode(root_dentry));
+ ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
+ ovl_dentry_lower(root_dentry), NULL);
+
+ sb->s_root = root_dentry;
+
+ return 0;
+
+out_free_oe:
+ ovl_entry_stack_free(oe);
+ kfree(oe);
+out_err:
+ path_put(&upperpath);
+ ovl_free_fs(ofs);
+out:
+ return err;
+}
+
+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *raw_data)
+{
+ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
+}
+
+static struct file_system_type ovl_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "overlay",
+ .mount = ovl_mount,
+ .kill_sb = kill_anon_super,
+};
+MODULE_ALIAS_FS("overlay");
+
+static void ovl_inode_init_once(void *foo)
+{
+ struct ovl_inode *oi = foo;
+
+ inode_init_once(&oi->vfs_inode);
+}
+
+static int __init ovl_init(void)
+{
+ int err;
+
+ ovl_inode_cachep = kmem_cache_create("ovl_inode",
+ sizeof(struct ovl_inode), 0,
+ (SLAB_RECLAIM_ACCOUNT|
+ SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+ ovl_inode_init_once);
+ if (ovl_inode_cachep == NULL)
+ return -ENOMEM;
+
+ err = register_filesystem(&ovl_fs_type);
+ if (err)
+ kmem_cache_destroy(ovl_inode_cachep);
+
+ return err;
+}
+
+static void __exit ovl_exit(void)
+{
+ unregister_filesystem(&ovl_fs_type);
+
+ /*
+ * Make sure all delayed rcu free inodes are flushed before we
+ * destroy cache.
+ */
+ rcu_barrier();
+ kmem_cache_destroy(ovl_inode_cachep);
+
+}
+
+module_init(ovl_init);
+module_exit(ovl_exit);