From: Ziyang Zhang <ZiyangZhang@linux.alibaba.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: axboe@kernel.dk, xiaoguang.wang@linux.alibaba.com,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
joseph.qi@linux.alibaba.com
Subject: Re: [PATCH V3 5/7] ublk_drv: consider recovery feature in aborting mechanism
Date: Tue, 20 Sep 2022 13:03:04 +0800 [thread overview]
Message-ID: <dd6cfbb2-c10d-c123-bcf7-22abbc4260ac@linux.alibaba.com> (raw)
In-Reply-To: <YylGPHg+hvY8f9+U@T590>
On 2022/9/20 12:49, Ming Lei wrote:
> On Tue, Sep 20, 2022 at 12:39:31PM +0800, Ziyang Zhang wrote:
>> On 2022/9/20 12:01, Ming Lei wrote:
>>> On Tue, Sep 20, 2022 at 11:24:12AM +0800, Ziyang Zhang wrote:
>>>> On 2022/9/20 11:04, Ming Lei wrote:
>>>>> On Tue, Sep 20, 2022 at 09:49:33AM +0800, Ziyang Zhang wrote:
>>>>>
>>>>> Follows the delta patch against patch 5 for showing the idea:
>>>>>
>>>>>
>>>>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
>>>>> index 4409a130d0b6..60c5786c4711 100644
>>>>> --- a/drivers/block/ublk_drv.c
>>>>> +++ b/drivers/block/ublk_drv.c
>>>>> @@ -656,7 +656,8 @@ static void ublk_complete_rq(struct request *req)
>>>>> * Also aborting may not be started yet, keep in mind that one failed
>>>>> * request may be issued by block layer again.
>>>>> */
>>>>> -static void __ublk_fail_req(struct ublk_io *io, struct request *req)
>>>>> +static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
>>>>> + struct request *req)
>>>>> {
>>>>> WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
>>>>>
>>>>> @@ -667,7 +668,10 @@ static void __ublk_fail_req(struct ublk_io *io, struct request *req)
>>>>> req->tag,
>>>>> io->flags);
>>>>> io->flags |= UBLK_IO_FLAG_ABORTED;
>>>>> - blk_mq_end_request(req, BLK_STS_IOERR);
>>>>> + if (ublk_queue_can_use_recovery_reissue(ubq))
>>>>> + blk_mq_requeue_request(req, false);
>>>>
>>>> Here is one problem:
>>>> We reset io->flags to 0 in ublk_queue_reinit() and it is called before new
>>>
>>> As we agreed, ublk_queue_reinit() will be moved to ublk_ch_release(), when there isn't
>>> any inflight request, which is completed by either ublk server or __ublk_fail_req().
>>>
>>> So clearing io->flags isn't related with quisceing device.
>>>
>>>> ubq_daemon with FETCH_REQ is accepted. ublk_abort_queue() is not protected with
>>>> ub_mutex and it is called many times in monitor_work. So same rq may be requeued
>>>> multiple times.
>>>
>>> UBLK_IO_FLAG_ABORTED is set for the slot, so one req is only ended or
>>> requeued just once.
>>
>> Yes, we can move ublk_queue_reinit() into ublk_ch_release(), but monitor_work is scheduled
>> periodically so ublk_abort_queue() is called multiple times. As ublk_queue_reinit() clear
>> io->flags, ublk_abort_queue() can requeue the same rq twice. Note that monitor_work can be
>> scheduled after ublk_ch_release().
>
> No, monitor work is supposed to be shutdown after in-flight requests are
> drained.
Let's add cancel_delayed_work_sync(&ub->monitor_work) in ublk_ch_release().
monitor_work should not be scheduled after ub's state is QUIESCED.
Regards,
Zhang.
next prev parent reply other threads:[~2022-09-20 5:03 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-13 4:17 [PATCH V3 0/7] ublk_drv: add USER_RECOVERY support ZiyangZhang
2022-09-13 4:17 ` [PATCH V3 1/7] ublk_drv: check 'current' instead of 'ubq_daemon' ZiyangZhang
2022-09-13 4:17 ` [PATCH V3 2/7] ublk_drv: refactor ublk_cancel_queue() ZiyangZhang
2022-09-13 4:17 ` [PATCH V3 3/7] ublk_drv: define macros for recovery feature and check them ZiyangZhang
2022-09-20 5:04 ` Ming Lei
2022-09-13 4:17 ` [PATCH V3 4/7] ublk_drv: requeue rqs with recovery feature enabled ZiyangZhang
2022-09-19 3:55 ` Ming Lei
2022-09-19 9:12 ` Ziyang Zhang
2022-09-19 12:39 ` Ming Lei
2022-09-20 1:31 ` Ziyang Zhang
2022-09-20 2:39 ` Ming Lei
2022-09-20 3:04 ` Ziyang Zhang
2022-09-20 3:18 ` Ming Lei
2022-09-20 3:34 ` Ziyang Zhang
2022-09-20 4:41 ` Ming Lei
2022-09-13 4:17 ` [PATCH V3 5/7] ublk_drv: consider recovery feature in aborting mechanism ZiyangZhang
2022-09-19 9:32 ` Ming Lei
2022-09-19 9:55 ` Ziyang Zhang
2022-09-19 12:33 ` Ming Lei
2022-09-20 1:49 ` Ziyang Zhang
2022-09-20 3:04 ` Ming Lei
2022-09-20 3:24 ` Ziyang Zhang
2022-09-20 4:01 ` Ming Lei
2022-09-20 4:39 ` Ziyang Zhang
2022-09-20 4:49 ` Ming Lei
2022-09-20 5:03 ` Ziyang Zhang [this message]
2022-09-20 4:45 ` Ziyang Zhang
2022-09-20 5:05 ` Ziyang Zhang
2022-09-13 4:17 ` [PATCH V3 6/7] ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support ZiyangZhang
2022-09-19 13:03 ` Ming Lei
2022-09-20 2:41 ` Ziyang Zhang
2022-09-13 4:17 ` [PATCH V3 7/7] ublk_drv: do not run monitor_work while ub's state is QUIESCED ZiyangZhang
2022-09-19 2:17 ` [PATCH V3 0/7] ublk_drv: add USER_RECOVERY support Ziyang Zhang
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