#unconditional
#val_type uint64_t
BTRFS_BLOCK_GROUP_DATA
BTRFS_BLOCK_GROUP_SYSTEM
BTRFS_BLOCK_GROUP_METADATA
BTRFS_BLOCK_GROUP_RAID0
BTRFS_BLOCK_GROUP_RAID1
BTRFS_BLOCK_GROUP_DUP
BTRFS_BLOCK_GROUP_RAID10
BTRFS_BLOCK_GROUP_RAID5
BTRFS_BLOCK_GROUP_RAID6
BTRFS_AVAIL_ALLOC_BIT_SINGLE
BTRFS_SPACE_INFO_GLOBAL_RSV