BMBT_EXNTFLAG_BITLEN
xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
irec->br_startoff = (l0 & xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
if (l0 >> (64 - BMBT_EXNTFLAG_BITLEN))