From 2293cae703cda162684ae966db6b1b4a11b5e88f Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@redhat.com>
Date: Wed, 21 Jun 2023 21:22:08 +0800
Subject: [PATCH] blk-mq: don't insert passthrough request into sw queue
In case of real io scheduler, q->elevator is set, so blk_mq_run_hw_queue()
may just check if scheduler queue has request to dispatch, see
__blk_mq_sched_dispatch_requests(). Then IO hang may be caused because
all passthorugh requests may stay in sw queue.
And any passthrough request should have been inserted to hctx->dispatch
always.
Reported-by: Guangwu Zhang <guazhang@redhat.com>
Fixes: d97217e7f024 ("blk-mq: don't queue plugged passthrough requests into scheduler")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230621132208.1142318-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-mq.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 16c524e371233..720b5061ffe88 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2728,7 +2728,12 @@ static void blk_mq_dispatch_plug_list(struct blk_plug *plug, bool from_sched)
percpu_ref_get(&this_hctx->queue->q_usage_counter);
/* passthrough requests should never be issued to the I/O scheduler */
- if (this_hctx->queue->elevator && !is_passthrough) {
+ if (is_passthrough) {
+ spin_lock(&this_hctx->lock);
+ list_splice_tail_init(&list, &this_hctx->dispatch);
+ spin_unlock(&this_hctx->lock);
+ blk_mq_run_hw_queue(this_hctx, from_sched);
+ } else if (this_hctx->queue->elevator) {
this_hctx->queue->elevator->type->ops.insert_requests(this_hctx,
&list, 0);
blk_mq_run_hw_queue(this_hctx, from_sched);
--
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