block: fix inconsistency in I/O stat accounting code

This forces in_flight to be zero when turning off or on the I/O stat
accounting and stops updating I/O stats in attempt_merge() when
accounting is turned off.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/block/blk.h b/block/blk.h
index 22043c2886c7..24fcaeeaf620 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -112,12 +112,14 @@ static inline int blk_cpu_to_group(int cpu)
 #endif
 }
 
-static inline int blk_do_io_stat(struct request_queue *q)
+static inline int blk_do_io_stat(struct request *rq)
 {
-        if (q)
-                return blk_queue_io_stat(q);
+        struct gendisk *disk = rq->rq_disk;
 
-        return 0;
+        if (!disk || !disk->queue)
+                return 0;
+
+        return blk_queue_io_stat(disk->queue) && (rq->cmd_flags & REQ_ELVPRIV);
 }
 
 #endif