linux-kernel - Re: [PATCH 0/2] Remove kiocb ki

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Message-ID: <418c57cb-04a2-d324-4b9a-59106427dfe5@gmail.com>
Date:   Thu, 9 Jul 2020 16:59:34 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
        io-uring@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kanchan Joshi <joshi.k@...sung.com>,
        Javier Gonzalez <javier.gonz@...sung.com>
Subject: Re: [PATCH 0/2] Remove kiocb ki_complete

On 09/07/2020 16:53, Matthew Wilcox wrote:
> On Thu, Jul 09, 2020 at 04:49:51PM +0300, Pavel Begunkov wrote:
>> On 09/07/2020 16:43, Matthew Wilcox wrote:
>>> On Thu, Jul 09, 2020 at 04:37:59PM +0300, Pavel Begunkov wrote:
>>>> Kanchan, could you take a look if you can hide it in req->cflags?
>>>
>>> No, that's not what cflags are for.  And besides, there's only 32 bits
>>> there.
>>
>> It's there to temporarily store cqe->cflags, if a request can't completed
>> right away. And req->{result,user_data,cflags} are basically an CQE inside
>> io_kiocb.
>>
>> So, it is there exactly for that reason, and whatever way it's going to be
>> encoded in an CQE, io_kiocb can fit it. That was my point.
> 
> But it's not going to be encoded in the CQE.  Perhaps you should go back to
> the older thread and read the arguments there.

Ok, if the thread is stopped on the version with indirection. I just looked the
last sent patch.

If so, we can also store offset before adding an CQE and getting by with local
vars only. Just a thought.

-- 
Pavel Begunkov