linux-kernel - Re: [PATCH V5 1/2] ublk_drv: add io_uring based userspace block driver

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Date:   Fri, 15 Jul 2022 14:07:17 +0800
From:   Ziyang Zhang <ZiyangZhang@...ux.alibaba.com>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        Xiaoguang Wang <xiaoguang.wang@...ux.alibaba.com>
Subject: Re: [PATCH V5 1/2] ublk_drv: add io_uring based userspace block
 driver

On 2022/7/15 10:04, Ming Lei wrote:
> On Thu, Jul 14, 2022 at 09:23:40PM +0800, Ziyang Zhang wrote:
>> On 2022/7/14 18:48, Ming Lei wrote:
>>> On Thu, Jul 14, 2022 at 06:20:38PM +0800, Ziyang Zhang wrote:
>>>> On 2022/7/13 22:07, Ming Lei wrote:
>>>>> This is the driver part of userspace block driver(ublk driver), the other
>>>>> part is userspace daemon part(ublksrv)[1].
>>>>>
...
>>
>> Put it together:
>>
>> When daemon is PF_EXITING:
>>
>> 1) current ublk_io: aborted immediately in task_work
> 
> Precisely it is just that ublk io request is ended immediately, so io->flags
> won't be touched.
> 
>>
>> 2) UBLK_IO_FLAG_ACTIVE set: aborted in ublk_daemon_monitor_work
> 
> This part is important for making forward progress, that is why it has
> to be done in a wq context.
> 
>>
>> 3) UBLK_IO_FLAG_ACTIVE unset: send cqe with UBLK_IO_RES_ABORT

Oh... sorry for one mistake. case 2) and 3) should be swapped:

ublk_daemon_monitor_work(): abort blk-mq IOs if UBLK_IO_FLAG_ACTIVE is unset

ublk_cancel_queue(): send cqes with UBLK_IO_RES_ABORT if UBLK_IO_FLAG_ACTIVE is set