Re: [PATCH v5 2/8] block: Introduce BLK_MQ_REQ_PM

[Can Guo <cang@codeaurora.org>]

On 2020-12-09 13:29, Bart Van Assche wrote:
> Introduce the BLK_MQ_REQ_PM flag. This flag makes the request 
> allocation
> functions set RQF_PM. This is the first step towards removing
> BLK_MQ_REQ_PREEMPT.
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Jens Axboe <axboe@kernel.dk>

Reviewed-by: Can Guo <cang@codeaurora.org>

> Cc: Alan Stern <stern@rowland.harvard.edu>
> Cc: Stanley Chu <stanley.chu@mediatek.com>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Can Guo <cang@codeaurora.org>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  block/blk-core.c       | 7 ++++---
>  block/blk-mq.c         | 2 ++
>  include/linux/blk-mq.h | 2 ++
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 2db8bda43b6e..10696f9fb6ac 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -424,11 +424,11 @@ EXPORT_SYMBOL(blk_cleanup_queue);
>  /**
>   * blk_queue_enter() - try to increase q->q_usage_counter
>   * @q: request queue pointer
> - * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
> + * @flags: BLK_MQ_REQ_NOWAIT, BLK_MQ_REQ_PM and/or BLK_MQ_REQ_PREEMPT
>   */
>  int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
>  {
> -	const bool pm = flags & BLK_MQ_REQ_PREEMPT;
> +	const bool pm = flags & (BLK_MQ_REQ_PM | BLK_MQ_REQ_PREEMPT);
> 
>  	while (true) {
>  		bool success = false;
> @@ -630,7 +630,8 @@ struct request *blk_get_request(struct
> request_queue *q, unsigned int op,
>  	struct request *req;
> 
>  	WARN_ON_ONCE(op & REQ_NOWAIT);
> -	WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT));
> +	WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PM |
> +			       BLK_MQ_REQ_PREEMPT));
> 
>  	req = blk_mq_alloc_request(q, op, flags);
>  	if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 1b25ec2fe9be..b5880a1fb38d 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -292,6 +292,8 @@ static struct request *blk_mq_rq_ctx_init(struct
> blk_mq_alloc_data *data,
>  	rq->mq_hctx = data->hctx;
>  	rq->rq_flags = 0;
>  	rq->cmd_flags = data->cmd_flags;
> +	if (data->flags & BLK_MQ_REQ_PM)
> +		rq->rq_flags |= RQF_PM;
>  	if (data->flags & BLK_MQ_REQ_PREEMPT)
>  		rq->rq_flags |= RQF_PREEMPT;
>  	if (blk_queue_io_stat(data->q))
> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
> index b23eeca4d677..c00e856c6fb1 100644
> --- a/include/linux/blk-mq.h
> +++ b/include/linux/blk-mq.h
> @@ -444,6 +444,8 @@ enum {
>  	BLK_MQ_REQ_NOWAIT	= (__force blk_mq_req_flags_t)(1 << 0),
>  	/* allocate from reserved pool */
>  	BLK_MQ_REQ_RESERVED	= (__force blk_mq_req_flags_t)(1 << 1),
> +	/* set RQF_PM */
> +	BLK_MQ_REQ_PM		= (__force blk_mq_req_flags_t)(1 << 2),
>  	/* set RQF_PREEMPT */
>  	BLK_MQ_REQ_PREEMPT	= (__force blk_mq_req_flags_t)(1 << 3),
>  };