From d666ba98f849ad44c4405ecc2180390ebe80f4f9 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 27 Nov 2018 17:02:25 -0700 Subject: blk-mq: add mq_ops->commit_rqs() blk-mq passes information to the hardware about any given request being the last that we will issue in this sequence. The point is that hardware can defer costly doorbell type writes to the last request. But if we run into errors issuing a sequence of requests, we may never send the request with bd->last == true set. For that case, we need a hook that tells the hardware that nothing else is coming right now. For failures returned by the drivers ->queue_rq() hook, the driver is responsible for flushing pending requests, if it uses bd->last to optimize that part. This works like before, no changes there. Reviewed-by: Omar Sandoval Reviewed-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- include/linux/blk-mq.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux/blk-mq.h') diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index b8de11e0603b..467f1dd21ccf 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -117,6 +117,7 @@ struct blk_mq_queue_data { typedef blk_status_t (queue_rq_fn)(struct blk_mq_hw_ctx *, const struct blk_mq_queue_data *); +typedef void (commit_rqs_fn)(struct blk_mq_hw_ctx *); /* takes rq->cmd_flags as input, returns a hardware type index */ typedef int (rq_flags_to_type_fn)(struct request_queue *, unsigned int); typedef bool (get_budget_fn)(struct blk_mq_hw_ctx *); @@ -144,6 +145,15 @@ struct blk_mq_ops { */ queue_rq_fn *queue_rq; + /* + * If a driver uses bd->last to judge when to submit requests to + * hardware, it must define this function. In case of errors that + * make us stop issuing further requests, this hook serves the + * purpose of kicking the hardware (which the last request otherwise + * would have done). + */ + commit_rqs_fn *commit_rqs; + /* * Return a queue map type for the given request/bio flags */ -- cgit v1.2.3-70-g09d2