btrfs: remove detached list from btrfs_backref_cache

We don't ever look at this list, remove it.

Signed-off-by: Josef Bacik <[email protected]>

fs/btrfs/backref.c

@@ -3021,7 +3021,6 @@ void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
 	cache->rb_root = RB_ROOT;
 	for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 		INIT_LIST_HEAD(&cache->pending[i]);
-	INIT_LIST_HEAD(&cache->detached);
 	INIT_LIST_HEAD(&cache->pending_edge);
 	INIT_LIST_HEAD(&cache->useless_node);
 	cache->fs_info = fs_info;
@@ -3158,7 +3157,6 @@ void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
 
 	ASSERT(list_empty(&cache->pending_edge));
 	ASSERT(list_empty(&cache->useless_node));
-	ASSERT(list_empty(&cache->detached));
 	ASSERT(!cache->nr_nodes);
 	ASSERT(!cache->nr_edges);
 }

fs/btrfs/backref.h

@@ -393,8 +393,6 @@ struct btrfs_backref_cache {
 	 * level blocks may not reflect the new location
 	 */
 	struct list_head pending[BTRFS_MAX_LEVEL];
-	/* List of detached backref node. */
-	struct list_head detached;
 
 	u64 last_trans;
 

fs/btrfs/relocation.c

@@ -367,7 +367,6 @@ static bool handle_useless_nodes(struct reloc_control *rc,
 		 * cache to avoid unnecessary backref lookup.
 		 */
 		if (cur->level > 0) {
-			list_add(&cur->list, &cache->detached);
 			cur->detached = 1;
 		} else {
 			rb_erase(&cur->rb_node, &cache->rb_root);