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-core.c b/block/blk-core.c
index 853f92749202..99e20cca37e1 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2354,7 +2354,7 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
         if (!req->bio)
                 return false;
 
-        trace_block_rq_complete(req->q, req);
+        trace_block_rq_complete(req->q, req, nr_bytes);
 
         /*
          * For fs requests, rq is just carrier of independent bio's