| From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.9 022/111] blk-mq: always allow reserved allocation in hctx_may_queue | Date | Sun, 18 Oct 2020 15:16:38 -0400 |
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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 cdced4aca2e81..96425e4bd2b2c 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; -- 2.25.1
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