block: check bio_mergeable() early before merging

After bio splitting is introduced, one bio can be splitted
and it is marked as NOMERGE because it is too fat to be merged,
so check bio_mergeable() earlier to avoid to try to merge it
unnecessarily.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2015-10-20 23:13:55 +08:00 коммит произвёл Jens Axboe
Родитель e18378a60e
Коммит 7460d389c0
1 изменённых файлов: 1 добавлений и 1 удалений

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@ -420,7 +420,7 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
* noxmerges: Only simple one-hit cache try
* merges: All merge tries attempted
*/
if (blk_queue_nomerges(q))
if (blk_queue_nomerges(q) || !bio_mergeable(bio))
return ELEVATOR_NO_MERGE;
/*