BLKFREE2IDX
ffslot = BLKFREE2IDX(nfree / DIRALIGN);
ofidx = BLKFREE2IDX(dh->dh_blkfree[block]);
nfidx = BLKFREE2IDX(dh->dh_blkfree[block]);
if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx)