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Subject: Re: [PATCH] loop: make autoclear operation asynchronous
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From:   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To:     Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>
Cc:     Dave Chinner <dchinner@redhat.com>, linux-block@vger.kernel.org,
        Jens Axboe <axboe@kernel.dk>
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Can we apply https://lkml.kernel.org/r/d1f760f9-cdb2-f40d-33d8-bfa517c731be@i-love.sakura.ne.jp ?

On 2021/12/03 20:01, Tetsuo Handa wrote:
> On 2021/12/03 15:50, Christoph Hellwig wrote:
>> task_work_add sounds nice, but it is currently not exported which might
>> be for a reason (I don't really have any experience with it).
> 
> I didn't find a reason not to export. But generally task_work_add() users
> seem to implement a fallback which uses a WQ in case task_work_add() failed
> (i.e. exit_task_work() was already called from do_exit()) or task_work_add()
> cannot be used (e.g. the caller is a kernel thread).
> 
> I don't know if there is possibility that a kernel thread calls blkdev_put(),
> but implementing the fallback path after all requires WQ. Thus, I think that
> starting from WQ only and see if something breaks is fine.
>