linux-kernel - Re: [PATCH V3 4/7] ublk_drv: requeue rqs with recovery feature enabled

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Message-ID: <YyfoQuw18kOynxcC@T590>
Date:   Mon, 19 Sep 2022 11:55:46 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     ZiyangZhang <ZiyangZhang@...ux.alibaba.com>
Cc:     axboe@...nel.dk, xiaoguang.wang@...ux.alibaba.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        joseph.qi@...ux.alibaba.com, ming.lei@...hat.com
Subject: Re: [PATCH V3 4/7] ublk_drv: requeue rqs with recovery feature
 enabled

On Tue, Sep 13, 2022 at 12:17:04PM +0800, ZiyangZhang wrote:
> With recovery feature enabled, in ublk_queue_rq or task work
> (in exit_task_work or fallback wq), we requeue rqs instead of
> ending(aborting) them. Besides, No matter recovery feature is enabled
> or disabled, we schedule monitor_work immediately.
> 
> Signed-off-by: ZiyangZhang <ZiyangZhang@...ux.alibaba.com>
> ---
>  drivers/block/ublk_drv.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 23337bd7c105..b067f33a1913 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -682,6 +682,21 @@ static void ubq_complete_io_cmd(struct ublk_io *io, int res)
>  
>  #define UBLK_REQUEUE_DELAY_MS	3
>  
> +static inline void __ublk_abort_rq_in_task_work(struct ublk_queue *ubq,
> +		struct request *rq)
> +{
> +	pr_devel("%s: %s q_id %d tag %d io_flags %x.\n", __func__,
> +			(ublk_queue_can_use_recovery(ubq)) ? "requeue" : "abort",
> +			ubq->q_id, rq->tag, ubq->ios[rq->tag].flags);
> +	/* We cannot process this rq so just requeue it. */
> +	if (ublk_queue_can_use_recovery(ubq)) {
> +		blk_mq_requeue_request(rq, false);
> +		blk_mq_delay_kick_requeue_list(rq->q, UBLK_REQUEUE_DELAY_MS);

Here you needn't to kick requeue list since we know it can't make
progress. And you can do that once before deleting gendisk
or the queue is recovered.

> +	} else {
> +		blk_mq_end_request(rq, BLK_STS_IOERR);
> +	}
> +}
> +
>  static inline void __ublk_rq_task_work(struct request *req)
>  {
>  	struct ublk_queue *ubq = req->mq_hctx->driver_data;
> @@ -704,7 +719,7 @@ static inline void __ublk_rq_task_work(struct request *req)
>  	 * (2) current->flags & PF_EXITING.
>  	 */
>  	if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
> -		blk_mq_end_request(req, BLK_STS_IOERR);
> +		__ublk_abort_rq_in_task_work(ubq, req);
>  		mod_delayed_work(system_wq, &ub->monitor_work, 0);
>  		return;
>  	}
> @@ -779,6 +794,21 @@ static void ublk_rq_task_work_fn(struct callback_head *work)
>  	__ublk_rq_task_work(req);
>  }
>  
> +static inline blk_status_t __ublk_abort_rq(struct ublk_queue *ubq,
> +		struct request *rq)
> +{
> +	pr_devel("%s: %s q_id %d tag %d io_flags %x.\n", __func__,
> +			(ublk_queue_can_use_recovery(ubq)) ? "requeue" : "abort",
> +			ubq->q_id, rq->tag, ubq->ios[rq->tag].flags);
> +	/* We cannot process this rq so just requeue it. */
> +	if (ublk_queue_can_use_recovery(ubq)) {
> +		blk_mq_requeue_request(rq, false);
> +		blk_mq_delay_kick_requeue_list(rq->q, UBLK_REQUEUE_DELAY_MS);

Same with above.


Thanks,
Ming