SG_DXFER_NONE
hdr.dxfer_direction = SG_DXFER_NONE;
if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE))
hp->dxfer_direction = (mxsize > 0) ? SG_DXFER_FROM_DEV : SG_DXFER_NONE;