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authorJens Axboe <axboe@fb.com>2015-05-29 13:10:23 -0600
committerJens Axboe <axboe@fb.com>2015-05-29 13:10:23 -0600
commitbeefa6ba7bf304d3de3a02cb7366fb0a7d6b27ab (patch)
tree17390185e6e56a3d9bdebd0997d8f95025a30d09
parentf6454b049d81bb3d732b6a8afde08420589c6af9 (diff)
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 <axboe@fb.com>
-rw-r--r--block/blk-merge.c3
1 files changed, 2 insertions, 1 deletions
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];