blk-mq: allow changing of queue depth through sysfs

For request_fn based devices, the block layer exports a 'nr_requests'
file through sysfs to allow adjusting of queue depth on the fly.
Currently this returns -EINVAL for blk-mq, since it's not wired up.
Wire this up for blk-mq, so that it now also always dynamic
adjustments of the allowed queue depth for any given block device
managed by blk-mq.

Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 9 insertions, 36 deletions

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 7500f87..4d6811a 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -48,11 +48,10 @@ static ssize_t queue_requests_show(struct request_queue *q, char *page)
 static ssize_t
 queue_requests_store(struct request_queue *q, const char *page, size_t count)
 {
-	struct request_list *rl;
 	unsigned long nr;
-	int ret;
+	int ret, err;
 
-	if (!q->request_fn)
+	if (!q->request_fn && !q->mq_ops)
 		return -EINVAL;
 
 	ret = queue_var_store(&nr, page, count);
@@ -62,40 +61,14 @@ queue_requests_store(struct request_queue *q, const char *page, size_t count)
 	if (nr < BLKDEV_MIN_RQ)
 		nr = BLKDEV_MIN_RQ;
 
-	spin_lock_irq(q->queue_lock);
-	q->nr_requests = nr;
-	blk_queue_congestion_threshold(q);
-
-	/* congestion isn't cgroup aware and follows root blkcg for now */
-	rl = &q->root_rl;
-
-	if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
-		blk_set_queue_congested(q, BLK_RW_SYNC);
-	else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
-		blk_clear_queue_congested(q, BLK_RW_SYNC);
-
-	if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
-		blk_set_queue_congested(q, BLK_RW_ASYNC);
-	else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
-		blk_clear_queue_congested(q, BLK_RW_ASYNC);
-
-	blk_queue_for_each_rl(rl, q) {
-		if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
-			blk_set_rl_full(rl, BLK_RW_SYNC);
-		} else {
-			blk_clear_rl_full(rl, BLK_RW_SYNC);
-			wake_up(&rl->wait[BLK_RW_SYNC]);
-		}
-
-		if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
-			blk_set_rl_full(rl, BLK_RW_ASYNC);
-		} else {
-			blk_clear_rl_full(rl, BLK_RW_ASYNC);
-			wake_up(&rl->wait[BLK_RW_ASYNC]);
-		}
-	}
+	if (q->request_fn)
+		err = blk_update_nr_requests(q, nr);
+	else
+		err = blk_mq_update_nr_requests(q, nr);
+
+	if (err)
+		return err;
 
-	spin_unlock_irq(q->queue_lock);
 	return ret;
 }