blktrace: fix accounting of partially completed requests

trace_block_rq_complete does not take into account that request can
be partially completed, so we can get the following incorrect output
of blkparser:

  C   R 232 + 240 [0]
  C   R 240 + 232 [0]
  C   R 248 + 224 [0]
  C   R 256 + 216 [0]

but should be:

  C   R 232 + 8 [0]
  C   R 240 + 8 [0]
  C   R 248 + 8 [0]
  C   R 256 + 8 [0]

Also, the whole output summary statistics of completed requests and
final throughput will be incorrect.

This patch takes into account real completion size of the request and
fixes wrong completion accounting.

Signed-off-by: Roman Pen <r.peniaev@gmail.com>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@redhat.com>
CC: linux-kernel@vger.kernel.org
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6468a715a0e..01d8735db8d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -309,7 +309,7 @@ void blk_mq_end_io(struct request *rq, int error)
 	struct bio *bio = rq->bio;
 	unsigned int bytes = 0;
 
-	trace_block_rq_complete(rq->q, rq);
+	trace_block_rq_complete(rq->q, rq, blk_rq_bytes(rq));
 
 	while (bio) {
 		struct bio *next = bio->bi_next;