linux-kernel - Re: [RESEND PATCH V5 4/7] ublk_drv: consider recovery feature in aborting mechanism

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Date:   Fri, 23 Sep 2022 21:48:15 +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: [RESEND PATCH V5 4/7] ublk_drv: consider recovery feature in
 aborting mechanism

On Fri, Sep 23, 2022 at 02:15:02PM +0800, ZiyangZhang wrote:
> With USER_RECOVERY feature enabled, the monitor_work schedules
> quiesce_work after finding a dying ubq_daemon. The monitor_work
> should also abort all rqs issued to userspace before the ubq_daemon is
> dying. The quiesce_work's job is to:
> (1) quiesce request queue.
> (2) check if there is any INFLIGHT rq. If so, we retry until all these
>     rqs are requeued and become IDLE. These rqs should be requeued by
> 	ublk_queue_rq(), task work, io_uring fallback wq or monitor_work.
> (3) complete all ioucmds by calling io_uring_cmd_done(). We are safe to
>     do so because no ioucmd can be referenced now.
> (5) set ub's state to UBLK_S_DEV_QUIESCED, which means we are ready for
>     recovery. This state is exposed to userspace by GET_DEV_INFO.
> 
> The driver can always handle STOP_DEV and cleanup everything no matter
> ub's state is LIVE or QUIESCED. After ub's state is UBLK_S_DEV_QUIESCED,
> user can recover with new process.
> 
> Note: we do not change the default behavior with reocvery feature
> disabled. monitor_work still schedules stop_work and abort inflight
> rqs. And finally ublk_device is released.
> 
> Signed-off-by: ZiyangZhang <ZiyangZhang@...ux.alibaba.com>

Looks fine,

Reviewed-by: Ming Lei <ming.lei@...hat.com>


Thanks,
Ming