1 files changed, 4 insertions, 73 deletions

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index ea4ed85919ec..f3834f8d26b4 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -232,70 +232,6 @@ static struct btrfs_backref_node *walk_down_backref(
 	return NULL;
 }
 
-static void update_backref_node(struct btrfs_backref_cache *cache,
-				struct btrfs_backref_node *node, u64 bytenr)
-{
-	struct rb_node *rb_node;
-	rb_erase(&node->rb_node, &cache->rb_root);
-	node->bytenr = bytenr;
-	rb_node = rb_simple_insert(&cache->rb_root, node->bytenr, &node->rb_node);
-	if (rb_node)
-		btrfs_backref_panic(cache->fs_info, bytenr, -EEXIST);
-}
-
-/*
- * update backref cache after a transaction commit
- */
-static int update_backref_cache(struct btrfs_trans_handle *trans,
-				struct btrfs_backref_cache *cache)
-{
-	struct btrfs_backref_node *node;
-	int level = 0;
-
-	if (cache->last_trans == 0) {
-		cache->last_trans = trans->transid;
-		return 0;
-	}
-
-	if (cache->last_trans == trans->transid)
-		return 0;
-
-	/*
-	 * detached nodes are used to avoid unnecessary backref
-	 * lookup. transaction commit changes the extent tree.
-	 * so the detached nodes are no longer useful.
-	 */
-	while (!list_empty(&cache->detached)) {
-		node = list_entry(cache->detached.next,
-				  struct btrfs_backref_node, list);
-		btrfs_backref_cleanup_node(cache, node);
-	}
-
-	while (!list_empty(&cache->changed)) {
-		node = list_entry(cache->changed.next,
-				  struct btrfs_backref_node, list);
-		list_del_init(&node->list);
-		BUG_ON(node->pending);
-		update_backref_node(cache, node, node->new_bytenr);
-	}
-
-	/*
-	 * some nodes can be left in the pending list if there were
-	 * errors during processing the pending nodes.
-	 */
-	for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
-		list_for_each_entry(node, &cache->pending[level], list) {
-			BUG_ON(!node->pending);
-			if (node->bytenr == node->new_bytenr)
-				continue;
-			update_backref_node(cache, node, node->new_bytenr);
-		}
-	}
-
-	cache->last_trans = 0;
-	return 1;
-}
-
 static bool reloc_root_is_dead(const struct btrfs_root *root)
 {
 	/*
@@ -551,9 +487,6 @@ static int clone_backref_node(struct btrfs_trans_handle *trans,
 	struct btrfs_backref_edge *new_edge;
 	struct rb_node *rb_node;
 
-	if (cache->last_trans > 0)
-		update_backref_cache(trans, cache);
-
 	rb_node = rb_simple_search(&cache->rb_root, src->commit_root->start);
 	if (rb_node) {
 		node = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
@@ -923,7 +856,7 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
 	btrfs_grab_root(reloc_root);
 
 	/* root->reloc_root will stay until current relocation finished */
-	if (fs_info->reloc_ctl->merge_reloc_tree &&
+	if (fs_info->reloc_ctl && fs_info->reloc_ctl->merge_reloc_tree &&
 	    btrfs_root_refs(root_item) == 0) {
 		set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
 		/*
@@ -3698,11 +3631,9 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 			break;
 		}
 restart:
-		if (update_backref_cache(trans, &rc->backref_cache)) {
-			btrfs_end_transaction(trans);
-			trans = NULL;
-			continue;
-		}
+		if (rc->backref_cache.last_trans != trans->transid)
+			btrfs_backref_release_cache(&rc->backref_cache);
+		rc->backref_cache.last_trans = trans->transid;
 
 		ret = find_next_extent(rc, path, &key);
 		if (ret < 0)