[PATCH v2 03/11] blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests()

John Garry
2021-08-09T14:36:29Z

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>
---
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 ae28f470893c..0e4825ca9869 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3624,8 +3624,6 @@ 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);
@@ -3643,9 +3641,13 @@ 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