On Wed, Nov 25, 2020 at 03:19:44PM +0800, Ming Lei wrote: > Not sure the new bio flag is really required for this case, just wondering > why not take the following simple way? BTW we are really going to run > out of bio flag. > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 55bcee5dc032..1139b1efd712 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2157,6 +2157,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio) > unsigned int nr_segs; > blk_qc_t cookie; > blk_status_t ret; > + struct bio *orig_bio = bio; > > blk_queue_bounce(q, &bio); > __blk_queue_split(&bio, &nr_segs); > @@ -2265,6 +2266,10 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio) > blk_mq_sched_insert_request(rq, false, true, true); > } > > + /* don't poll splitted bio */ > + if (orig_bio != bio) > + return BLK_QC_T_NONE; > + > return cookie; > queue_exit: > blk_queue_exit(q); Yeah, this looks simpler and more obvious, and it also catches the bounce buffering case (not that polling + bounce buffering should ever happen).
