blk_rq_nr_discard_segments
unsigned short segments = blk_rq_nr_discard_segments(req);
unsigned short segments = blk_rq_nr_discard_segments(req);
req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next);
unsigned short segments = blk_rq_nr_discard_segments(req);
unsigned short segments = blk_rq_nr_discard_segments(req), n = 0;