The field of 'q_usage_counter' is always fetched in fast path of every
block driver, and move it into front of 'request_queue', so it can be
fetched into 1st cacheline of 'request_queue' instance.

Tested-by: Veronika Kabatova <redacted>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <redacted>
---
 include/linux/blkdev.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7d82959e7b86..7b1e53084799 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h

@@ -397,6 +397,8 @@ struct request_queue {
 	struct request		*last_merge;
 	struct elevator_queue	*elevator;
 
+	struct percpu_ref	q_usage_counter;
+
 	struct blk_queue_stats	*stats;
 	struct rq_qos		*rq_qos;
 

@@ -569,7 +571,6 @@ struct request_queue {
 	 * percpu_ref_kill() and percpu_ref_reinit().
 	 */
 	struct mutex		mq_freeze_lock;
-	struct percpu_ref	q_usage_counter;
 
 	struct blk_mq_tag_set	*tag_set;
 	struct list_head	tag_set_list;

-- 
2.25.2