[PATCH v4 03/13] blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests()

[John Garry]

For shared sbitmap, if the call to blk_mq_tag_update_depth() was
successful for any hctx when hctx->sched_tags is not set, then it would be
successful for all (due to nature in which blk_mq_tag_update_depth()
fails).

As such, there is no need to call blk_mq_tag_resize_shared_sbitmap() for
each hctx. So relocate the call until after the hctx iteration under the
!q->elevator check, which is equivalent (to !hctx->sched_tags).

Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
 block/blk-mq.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2316ff27c1f5..1a4bb2db30e5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3616,8 +3616,6 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 		if (!hctx->sched_tags) {
 			ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
 							false);
-			if (!ret && blk_mq_is_sbitmap_shared(set->flags))
-				blk_mq_tag_resize_shared_sbitmap(set, nr);
 		} else {
 			ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
 							nr, true);
@@ -3635,9 +3633,13 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	}
 	if (!ret) {
 		q->nr_requests = nr;
-		if (q->elevator && blk_mq_is_sbitmap_shared(set->flags))
-			sbitmap_queue_resize(&q->sched_bitmap_tags,
-					     nr - set->reserved_tags);
+		if (blk_mq_is_sbitmap_shared(set->flags)) {
+			if (q->elevator)
+				sbitmap_queue_resize(&q->sched_bitmap_tags,
+						     nr - set->reserved_tags);
+			else
+				blk_mq_tag_resize_shared_sbitmap(set, nr);
+		}
 	}
 
 	blk_mq_unquiesce_queue(q);
-- 
2.26.2