cd_blkstart
if (curr->cd_blkstart <= blkno &&
((blkno - curr->cd_blkstart) <<
((blkno - curr->cd_blkstart) <<
curr->cd_blkstart) << dev_bshift),
(long long)curr->cd_blkstart,
((blkno - curr->cd_blkstart) <<
cdesc[idx].cd_blkstart = blockBlkNo;