fold destroy_super() into __put_super()

There's only one caller of destroy_super() left now.  Fold it there,
and replace those list_lru_destroy() calls with checks that they
had already been done (as they should have, when we were dropping
the last active reference).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/super.c

@@ -154,23 +154,6 @@ static void destroy_super_rcu(struct rcu_head *head)
 	schedule_work(&s->destroy_work);
 }
 
-/**
- *	destroy_super	-	frees a superblock
- *	@s: superblock to free
- *
- *	Frees a superblock.
- */
-static void destroy_super(struct super_block *s)
-{
-	list_lru_destroy(&s->s_dentry_lru);
-	list_lru_destroy(&s->s_inode_lru);
-	security_sb_free(s);
-	WARN_ON(!list_empty(&s->s_mounts));
-	put_user_ns(s->s_user_ns);
-	kfree(s->s_subtype);
-	call_rcu(&s->rcu, destroy_super_rcu);
-}
-
 /* Free a superblock that has never been seen by anyone */
 static void destroy_unused_super(struct super_block *s)
 {
@@ -280,11 +263,17 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
 /*
  * Drop a superblock's refcount.  The caller must hold sb_lock.
  */
-static void __put_super(struct super_block *sb)
+static void __put_super(struct super_block *s)
 {
-	if (!--sb->s_count) {
-		list_del_init(&sb->s_list);
-		destroy_super(sb);
+	if (!--s->s_count) {
+		list_del_init(&s->s_list);
+		WARN_ON(s->s_dentry_lru.node);
+		WARN_ON(s->s_inode_lru.node);
+		WARN_ON(!list_empty(&s->s_mounts));
+		security_sb_free(s);
+		put_user_ns(s->s_user_ns);
+		kfree(s->s_subtype);
+		call_rcu(&s->rcu, destroy_super_rcu);
 	}
 }