blk-mq: blk-mq: check quiesce state before queue_rqs

The low level drivers don't expect to see new requests after a
successful quiesce completes. Check the queue quiesce state within the
rcu protected area prior to calling the driver's queue_rqs().

Fixes: 3c67d44de787 ("block: add mq_ops->queue_rqs hook")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20211220205919.180191-1-kbusch@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 51991232824a519e0439ecba57386b8d4527f9d8..0d7c9d3e0329395e91a5db4fd5e7434552e49be3 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2549,6 +2549,14 @@ static void blk_mq_plug_issue_direct(struct blk_plug *plug, bool from_schedule)
                blk_mq_commit_rqs(hctx, &queued, from_schedule);
 }
 
+static void __blk_mq_flush_plug_list(struct request_queue *q,
+                                    struct blk_plug *plug)
+{
+       if (blk_queue_quiesced(q))
+               return;
+       q->mq_ops->queue_rqs(&plug->mq_list);
+}
+
 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 {
        struct blk_mq_hw_ctx *this_hctx;
@@ -2580,7 +2588,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
                if (q->mq_ops->queue_rqs &&
                    !(rq->mq_hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
                        blk_mq_run_dispatch_ops(q,
-                               q->mq_ops->queue_rqs(&plug->mq_list));
+                               __blk_mq_flush_plug_list(q, plug));
                        if (rq_list_empty(plug->mq_list))
                                return;
                }