make configfs_pin_fs() return root dentry on success

... and make configfs_mnt static
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/configfs/configfs_internal.h

@@ -58,7 +58,6 @@ struct configfs_dirent {
 extern struct mutex configfs_symlink_mutex;
 extern spinlock_t configfs_dirent_lock;
 
-extern struct vfsmount * configfs_mount;
 extern struct kmem_cache *configfs_dir_cachep;
 
 extern int configfs_is_root(struct config_item *item);
@@ -80,7 +79,7 @@ extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
 extern void configfs_drop_dentry(struct configfs_dirent *sd, struct dentry *parent);
 extern int configfs_setattr(struct dentry *dentry, struct iattr *iattr);
 
-extern int configfs_pin_fs(void);
+extern struct dentry *configfs_pin_fs(void);
 extern void configfs_release_fs(void);
 
 extern struct rw_semaphore configfs_rename_sem;

fs/configfs/dir.c

@@ -1075,16 +1075,15 @@ int configfs_depend_item(struct configfs_subsystem *subsys,
 	 * Pin the configfs filesystem.  This means we can safely access
 	 * the root of the configfs filesystem.
 	 */
-	ret = configfs_pin_fs();
-	if (ret)
-		return ret;
+	root = configfs_pin_fs();
+	if (IS_ERR(root))
+		return PTR_ERR(root);
 
 	/*
 	 * Next, lock the root directory.  We're going to check that the
 	 * subsystem is really registered, and so we need to lock out
 	 * configfs_[un]register_subsystem().
 	 */
-	root = configfs_mount->mnt_root;
 	mutex_lock(&root->d_inode->i_mutex);
 
 	root_sd = root->d_fsdata;
@@ -1673,14 +1672,13 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
 	struct dentry *root;
 	struct configfs_dirent *sd;
 
-	err = configfs_pin_fs();
-	if (err)
-		return err;
+	root = configfs_pin_fs();
+	if (IS_ERR(root))
+		return PTR_ERR(root);
 
 	if (!group->cg_item.ci_name)
 		group->cg_item.ci_name = group->cg_item.ci_namebuf;
 
-	root = configfs_mount->mnt_root;
 	sd = root->d_fsdata;
 	link_group(to_config_group(sd->s_element), group);
 

fs/configfs/mount.c

@@ -37,7 +37,7 @@
 /* Random magic number */
 #define CONFIGFS_MAGIC 0x62656570
 
-struct vfsmount * configfs_mount = NULL;
+static struct vfsmount *configfs_mount = NULL;
 struct kmem_cache *configfs_dir_cachep;
 static int configfs_mnt_count = 0;
 
@@ -115,10 +115,11 @@ static struct file_system_type configfs_fs_type = {
 	.kill_sb	= kill_litter_super,
 };
 
-int configfs_pin_fs(void)
+struct dentry *configfs_pin_fs(void)
 {
-	return simple_pin_fs(&configfs_fs_type, &configfs_mount,
+	int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
 			     &configfs_mnt_count);
+	return err ? ERR_PTR(err) : configfs_mount->mnt_root;
 }
 
 void configfs_release_fs(void)