We only need to call it to resolve the blk_status_t -> errno mapping
if the status is different than BLK_STS_OK. Check that it is before
doing so.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
  block/blk-mq.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ffccc5f0f66a..fa5b12200404 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c

@@ -676,9 +676,11 @@ static void blk_account_io_completion(struct request *req, unsigned int bytes)
  bool blk_update_request(struct request *req, blk_status_t error,
  		unsigned int nr_bytes)
  {
-	int total_bytes;
+	int total_bytes, blk_errno = 0;
  
-	trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes);
+	if (unlikely(error != BLK_STS_OK))
+		blk_errno = blk_status_to_errno(error);
+	trace_block_rq_complete(req, blk_errno, nr_bytes);