block: Move a misplaced comment in queue_wb_lat_store()

blk_mq_quiesce_queue() does not wait for pending I/O to finish. Freezing
a queue waits for pending I/O to finish. Hence move the comment that
refers to waiting for pending I/O above the call that freezes the
request queue. This patch moves this comment back to the position where
it was when this comment was introduced. See also commit c125311d96b1
("blk-wbt: don't maintain inflight counts if disabled").

Cc: Christoph Hellwig <hch@lst.de>
Cc: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20250825151424.1653910-1-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 4a7f1a349998bae6cb84bd3eeb7ab4547d91a81a..c94b8b6ab024f7994769a69ebf7e51f540204efd 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -620,6 +620,11 @@ static ssize_t queue_wb_lat_store(struct gendisk *disk, const char *page,
        if (val < -1)
                return -EINVAL;
 
+       /*
+        * Ensure that the queue is idled, in case the latency update
+        * ends up either enabling or disabling wbt completely. We can't
+        * have IO inflight if that happens.
+        */
        memflags = blk_mq_freeze_queue(q);
 
        rqos = wbt_rq_qos(q);
@@ -638,11 +643,6 @@ static ssize_t queue_wb_lat_store(struct gendisk *disk, const char *page,
        if (wbt_get_min_lat(q) == val)
                goto out;
 
-       /*
-        * Ensure that the queue is idled, in case the latency update
-        * ends up either enabling or disabling wbt completely. We can't
-        * have IO inflight if that happens.
-        */
        blk_mq_quiesce_queue(q);
 
        mutex_lock(&disk->rqos_state_mutex);