QLW_IOCB_SEGS_PER_CMD
nsegs = ccb->ccb_dmamap->dm_nsegs - QLW_IOCB_SEGS_PER_CMD;
if (seg >= QLW_IOCB_SEGS_PER_CMD)
seg = QLW_IOCB_SEGS_PER_CMD;