[PATCH 5/8] fs/configfs: add superblock as attribute to configfs_pin_fs()

[Hannes Reinecke]

Each namspace might have its own superblock, so add it as an argument
to configfs_pin_fs() to ensure that the correct filesystem instance
will be pinned.

Signed-off-by: Hannes Reinecke <hare at kernel.org>
---
 fs/configfs/configfs_internal.h |  4 +--
 fs/configfs/dir.c               | 10 ++++----
 fs/configfs/mount.c             | 44 +++++++++++++++++++++++++++------
 3 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index e91f4249b83a..a91e97194c3d 100644
--- a/fs/configfs/configfs_internal.h
+++ b/fs/configfs/configfs_internal.h
@@ -90,8 +90,8 @@ extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
 extern int configfs_setattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, struct iattr *iattr);
 
-extern struct dentry *configfs_pin_fs(void);
-extern void configfs_release_fs(void);
+extern struct dentry *configfs_pin_fs(struct super_block *sb);
+extern void configfs_release_fs(struct super_block *sb);
 extern struct configfs_super_info *configfs_get_super_info(u64 ns_id);
 extern void configfs_put_super_info(struct configfs_super_info *info);
 
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index cf89c76ea7e6..6e111e3fd0e0 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1114,7 +1114,7 @@ int configfs_depend_item(struct configfs_subsystem *subsys,
 	 * Pin the configfs filesystem.  This means we can safely access
 	 * the root of the configfs filesystem.
 	 */
-	root = configfs_pin_fs();
+	root = configfs_pin_fs(NULL);
 	if (IS_ERR(root))
 		return PTR_ERR(root);
 
@@ -1141,7 +1141,7 @@ int configfs_depend_item(struct configfs_subsystem *subsys,
 	 * If we succeeded, the fs is pinned via other methods.  If not,
 	 * we're done with it anyway.  So release_fs() is always right.
 	 */
-	configfs_release_fs();
+	configfs_release_fs(NULL);
 
 	return ret;
 }
@@ -1896,7 +1896,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
 	if (WARN_ON(IS_ERR(info)))
 		return PTR_ERR(info);
 
-	root = configfs_pin_fs();
+	root = configfs_pin_fs(NULL);
 	if (IS_ERR(root)) {
 		err = PTR_ERR(root);
 		goto out_put;
@@ -1904,7 +1904,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
 
 	err = configfs_link_root(info, subsys, root);
 	if (err)
-		configfs_release_fs();
+		configfs_release_fs(NULL);
 
 out_put:
 	configfs_put_super_info(info);
@@ -1964,7 +1964,7 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
 	configfs_unlink_root(subsys);
 	unlink_group(group);
 	mutex_unlock(&info->subsys_mutex);
-	configfs_release_fs();
+	configfs_release_fs(NULL);
 	configfs_put_super_info(info);
 }
 
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index f49c8636eccb..8cf4bda14bec 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -177,18 +177,48 @@ static struct file_system_type configfs_fs_type = {
 };
 MODULE_ALIAS_FS("configfs");
 
-struct dentry *configfs_pin_fs(void)
+struct dentry *configfs_pin_fs(struct super_block *sb)
 {
-	int err = simple_pin_fs(&configfs_fs_type, &configfs_root->mnt,
-			     &configfs_root->mnt_count);
-	return err ? ERR_PTR(err) : configfs_root->mnt->mnt_root;
+	struct configfs_super_info *info = configfs_root;
+	int err;
+
+	if (sb) {
+		struct configfs_super_info *root = info;
+		struct dentry *dentry = sb->s_root;
+		struct vfsmount *mnt;
+
+		info = sb->s_fs_info;
+		if (!info->mnt) {
+			mnt = mnt_clone_direct(root->mnt, dentry);
+			if (IS_ERR(mnt))
+				return ERR_CAST(mnt);
+			info->mnt = mnt;
+		}
+		dget(dentry);
+		mntget(info->mnt);
+		info->mnt_count++;
+		return info->mnt->mnt_root;
+	}
+
+	err = simple_pin_fs(&configfs_fs_type, &info->mnt, &info->mnt_count);
+	if (err)
+		return ERR_PTR(err);
+
+	return info->mnt->mnt_root;
 }
 
-void configfs_release_fs(void)
+void configfs_release_fs(struct super_block *sb)
 {
-	simple_release_fs(&configfs_root->mnt, &configfs_root->mnt_count);
-}
+	struct configfs_super_info *info = configfs_root;
 
+	if (sb) {
+		info = sb->s_fs_info;
+		dput(sb->s_root);
+	}
+
+	pr_debug("release ns %llu\n", info->ns_id);
+	simple_release_fs(&info->mnt, &info->mnt_count);
+}
 
 static int __init configfs_init(void)
 {
-- 
2.51.0