diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 3a496b0d3d2b..7979449a58d6 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -57,8 +57,8 @@
 
 static struct btrfs_lockdep_keyset {
 	u64			id;		/* root objectid */
-	/* Longest entry: btrfs-free-space-00 */
-	char			names[BTRFS_MAX_LEVEL][20];
+	/* Longest entry: btrfs-block-group-00 */
+	char			names[BTRFS_MAX_LEVEL][24];
 	struct lock_class_key	keys[BTRFS_MAX_LEVEL];
 } btrfs_lockdep_keysets[] = {
 	{ .id = BTRFS_ROOT_TREE_OBJECTID,	DEFINE_NAME("root")	},
@@ -72,6 +72,7 @@ static struct btrfs_lockdep_keyset {
 	{ .id = BTRFS_DATA_RELOC_TREE_OBJECTID,	DEFINE_NAME("dreloc")	},
 	{ .id = BTRFS_UUID_TREE_OBJECTID,	DEFINE_NAME("uuid")	},
 	{ .id = BTRFS_FREE_SPACE_TREE_OBJECTID,	DEFINE_NAME("free-space") },
+	{ .id = BTRFS_BLOCK_GROUP_TREE_OBJECTID, DEFINE_NAME("block-group") },
 	{ .id = 0,				DEFINE_NAME("tree")	},
 };