#val_type uint64_t
BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF    (1ULL << 0)
BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL   (1ULL << 1)
BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS     (1ULL << 2)
BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO     (1ULL << 3)
BTRFS_FEATURE_INCOMPAT_COMPRESS_LZOv2   (1ULL << 4)
BTRFS_FEATURE_INCOMPAT_BIG_METADATA     (1ULL << 5)
BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF    (1ULL << 6)
BTRFS_FEATURE_INCOMPAT_RAID56           (1ULL << 7)
BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA  (1ULL << 8)
BTRFS_FEATURE_INCOMPAT_NO_HOLES         (1ULL << 9)