From: Ming Lei ming.lei@redhat.com
[ Upstream commit 285008501c65a3fcee05d2c2c26cbf629ceff2f0 ]
NVMe shares tagset between fabric queue and admin queue or between connect_q and NS queue, so hctx_may_queue() can be called to allocate request for these queues.
Tags can be reserved in these tagset. Before error recovery, there is often lots of in-flight requests which can't be completed, and new reserved request may be needed in error recovery path. However, hctx_may_queue() can always return false because there is too many in-flight requests which can't be completed during error handling. Finally, nothing can proceed.
Fix this issue by always allowing reserved tag allocation in hctx_may_queue(). This is reasonable because reserved tags are supposed to always be available.
Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Hannes Reinecke hare@suse.de Cc: David Milburn dmilburn@redhat.com Cc: Ewan D. Milne emilne@redhat.com Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-mq-tag.c | 3 ++- block/blk-mq.c | 5 +++-- 2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 32d82e23b0953..a1c1e7c611f7b 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -59,7 +59,8 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) static int __blk_mq_get_tag(struct blk_mq_alloc_data *data, struct sbitmap_queue *bt) { - if (!data->q->elevator && !hctx_may_queue(data->hctx, bt)) + if (!data->q->elevator && !(data->flags & BLK_MQ_REQ_RESERVED) && + !hctx_may_queue(data->hctx, bt)) return BLK_MQ_NO_TAG;
if (data->shallow_depth) diff --git a/block/blk-mq.c b/block/blk-mq.c index c27a61029cdd0..94a53d779c12b 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1105,10 +1105,11 @@ static bool __blk_mq_get_driver_tag(struct request *rq) if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) { bt = &rq->mq_hctx->tags->breserved_tags; tag_offset = 0; + } else { + if (!hctx_may_queue(rq->mq_hctx, bt)) + return false; }
- if (!hctx_may_queue(rq->mq_hctx, bt)) - return false; tag = __sbitmap_queue_get(bt); if (tag == BLK_MQ_NO_TAG) return false;