block: call elv_bio_merged() when merged

Commit 73c101011926 ("block: initial patch for on-stack per-task plugging")
removed calls to elv_bio_merged() when @bio merged with @req. Re-add them.

This in turn will update merged stats in associated group. That
should be safe as long as request has got reference to the blkio_group.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Divyesh Shah <dpshah@google.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 7369eeeafe23..c8303e9d919d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1122,6 +1122,7 @@ static bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
         req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
 
         drive_stat_acct(req, 0);
+        elv_bio_merged(q, req, bio);
         return true;
 }
 
@@ -1155,6 +1156,7 @@ static bool bio_attempt_front_merge(struct request_queue *q,
         req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
 
         drive_stat_acct(req, 0);
+        elv_bio_merged(q, req, bio);
         return true;
 }