linux-kernel - Re: [PATCH V5 3/7] ublk_drv: requeue rqs with recovery feature enabled

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Message-ID: <Yy0i6V/Qr1Wgw0Hu@T590>
Date:   Fri, 23 Sep 2022 11:07:21 +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
Subject: Re: [PATCH V5 3/7] ublk_drv: requeue rqs with recovery feature
 enabled

On Thu, Sep 22, 2022 at 02:17:30PM +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 | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 05bfbaa49696..a1cbcc5e9285 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -655,6 +655,16 @@ 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)
> +{
> +	/* We cannot process this rq so just requeue it. */
> +	if (ublk_queue_can_use_recovery(ubq))
> +		blk_mq_requeue_request(rq, false);
> +	else
> +		blk_mq_end_request(rq, BLK_STS_IOERR);
> +}

__ublk_abort_rq_in_task_work() can be renamed as __ublk_abort_rq(), then
be reused for the user of ublk_queue_rq(). 

> +
>  static inline void __ublk_rq_task_work(struct request *req)
>  {
>  	struct ublk_queue *ubq = req->mq_hctx->driver_data;
> @@ -677,7 +687,7 @@ 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;
>  	}
> @@ -752,6 +762,17 @@ 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)
> +{
> +	/* We cannot process this rq so just requeue it. */
> +	if (ublk_queue_can_use_recovery(ubq)) {
> +		blk_mq_requeue_request(rq, false);
> +		return BLK_STS_OK;
> +	}
> +	return BLK_STS_IOERR;
> +}

The above helper isn't needed.

> +
>  static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
>  		const struct blk_mq_queue_data *bd)
>  {
> @@ -769,7 +790,7 @@ static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
>  	if (unlikely(ubq_daemon_is_dying(ubq))) {
>   fail:
>  		mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
> -		return BLK_STS_IOERR;
> +		return __ublk_abort_rq(ubq, rq);

Then you can call __ublk_abort_rq(), and return BLK_STS_OK.


thanks.
Ming