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 7500f876dae4..4d6811ac13fd 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;
 }