Commit beefa6ba authored by Jens Axboe's avatar Jens Axboe
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block: only honor SG gap prevention for merges that contain data 



We can safely merge anything that wont generate an SG list entry,
so if the bio is data-less (discard), don't look at potential
SG gaps.

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent f6454b04

block/blk-merge.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -589,7 +589,8 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 
	    !blk_write_same_mergeable(rq->bio, bio))

	    !blk_write_same_mergeable(rq->bio, bio))

		return false;

		return false;





	if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) {

	/* Only check gaps if the bio carries data */

	if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) && bio_has_data(bio)) {

		struct bio_vec *bprev;

		struct bio_vec *bprev;





		bprev = &rq->biotail->bi_io_vec[rq->biotail->bi_vcnt - 1];

		bprev = &rq->biotail->bi_io_vec[rq->biotail->bi_vcnt - 1];