#val_type uint64_t
BTRFS_ROOT_TREE_OBJECTID 1ULL
BTRFS_EXTENT_TREE_OBJECTID 2ULL
BTRFS_CHUNK_TREE_OBJECTID 3ULL
BTRFS_DEV_TREE_OBJECTID 4ULL
BTRFS_FS_TREE_OBJECTID 5ULL
BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
BTRFS_CSUM_TREE_OBJECTID 7ULL
BTRFS_QUOTA_TREE_OBJECTID 8ULL
BTRFS_UUID_TREE_OBJECTID 9ULL
BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL
BTRFS_FIRST_FREE_OBJECTID 256ULL
BTRFS_LAST_FREE_OBJECTID -256ULL
UINT64_MAX -1ULL
