btrfs: add block-group tree to lockdep classes

The block group tree was not present among the lockdep classes. We could
get potentially lockdep warnings but so far none has been seen, also
because block-group-tree is a relatively new feature.

CC: stable@vger.kernel.org # 6.1+
Signed-off-by: David Sterba <dsterba@suse.com>

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")	},
 };