blk-mq: ensure that we set REQ_IO_STAT so diskstats work

If disk stats are enabled on the queue, a request needs to
be marked with REQ_IO_STAT for accounting to be active on
that request. This fixes an issue with virtio-blk not
showing up in /proc/diskstats after the conversion to
blk-mq.

Add QUEUE_FLAG_MQ_DEFAULT, setting stats and same cpu-group
completion on by default.

Reported-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f26ec20f6354..1b135d49b279 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -505,6 +505,9 @@ struct request_queue {
                                  (1 << QUEUE_FLAG_SAME_COMP)    |       \
                                  (1 << QUEUE_FLAG_ADD_RANDOM))
 
+#define QUEUE_FLAG_MQ_DEFAULT   ((1 << QUEUE_FLAG_IO_STAT) |            \
+                                 (1 << QUEUE_FLAG_SAME_COMP))
+
 static inline void queue_lockdep_assert_held(struct request_queue *q)
 {
         if (q->queue_lock)