Re: [PATCH V4 5/8] ublk_drv: consider recovery feature in aborting mechanism

Ziyang Zhang
2022-09-22T02:06:41Z

On 2022/9/22 08:18, Ming Lei wrote:
> On Wed, Sep 21, 2022 at 05:58:46PM +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@linux.alibaba.com>
>
> This version is close to be ready, just some debug logging needs
> be removed, see inline comment. Also I'd suggest you to learn to
> use bpftrace a bit, then basically you needn't to rely on kernel
> logging.
>
> If these logging is removed, you will see how simple the patch becomes
> compared with previous version.

Current version is simpler, thanks for reviewing, Ming.
Debug logging will be removed in V5 and I will send it out soon.

Regards,
Zhang