From beefa6ba7bf304d3de3a02cb7366fb0a7d6b27ab Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 29 May 2015 13:10:23 -0600 Subject: [PATCH] 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: Jens Axboe --- block/blk-merge.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index fd3fee81c23c..30a0d9f89017 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -589,7 +589,8 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) !blk_write_same_mergeable(rq->bio, bio)) 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; bprev = &rq->biotail->bi_io_vec[rq->biotail->bi_vcnt - 1]; -- 2.20.1