blk-mq: allow resize of scheduler requests

Add support for growing the tags associated with a hardware queue, for
the scheduler tags. Currently we only support resizing within the
limits of the original depth, change that so we can grow it as well by
allocating and replacing the existing scheduler tag set.

This is similar to how we could increase the software queue depth with
the legacy IO stack and schedulers.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>

1 files changed, 14 insertions, 5 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b365cde..ee69e5e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2561,6 +2561,9 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	if (!set)
 		return -EINVAL;
 
+	blk_mq_freeze_queue(q);
+	blk_mq_quiesce_queue(q);
+
 	ret = 0;
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (!hctx->tags)
@@ -2569,11 +2572,14 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 		 * If we're using an MQ scheduler, just update the scheduler
 		 * queue depth. This is similar to what the old code would do.
 		 */
-		if (!hctx->sched_tags)
-			ret = blk_mq_tag_update_depth(hctx->tags,
-							min(nr, set->queue_depth));
-		else
-			ret = blk_mq_tag_update_depth(hctx->sched_tags, nr);
+		if (!hctx->sched_tags) {
+			ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
+							min(nr, set->queue_depth),
+							false);
+		} else {
+			ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
+							nr, true);
+		}
 		if (ret)
 			break;
 	}
@@ -2581,6 +2587,9 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	if (!ret)
 		q->nr_requests = nr;
 
+	blk_mq_unfreeze_queue(q);
+	blk_mq_start_stopped_hw_queues(q, true);
+
 	return ret;
 }