blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests()

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@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/1633429419-228500-4-git-send-email-john.garry@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 03cbde7..240c04a 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3625,8 +3625,6 @@ 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);
@@ -3644,9 +3642,13 @@ 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);