From: Ming Lei ming.lei@redhat.com
[ Upstream commit 2293cae703cda162684ae966db6b1b4a11b5e88f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c763f0bc66371..b9f4546139894 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2735,7 +2735,12 @@ 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);