From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-aio@kvack.org, io-uring@vger.kernel.org,
linux-kernel@vger.kernel.org, Kanchan Joshi <joshi.k@samsung.com>,
Javier Gonzalez <javier.gonz@samsung.com>
Subject: Re: [PATCH 0/2] Remove kiocb ki_complete
Date: Thu, 9 Jul 2020 14:26:11 +0100 [thread overview]
Message-ID: <20200709132611.GA1382@infradead.org> (raw)
In-Reply-To: <20200709111036.GA12769@casper.infradead.org>
On Thu, Jul 09, 2020 at 12:10:36PM +0100, Matthew Wilcox wrote:
> On Thu, Jul 09, 2020 at 11:17:05AM +0100, Christoph Hellwig wrote:
> > I really don't like this series at all. If saves a single pointer
> > but introduces a complicated machinery that just doesn't follow any
> > natural flow. And there doesn't seem to be any good reason for it to
> > start with.
>
> Jens doesn't want the kiocb to grow beyond a single cacheline, and we
> want the ability to set the loff_t in userspace for an appending write,
> so the plan was to replace the ki_complete member in kiocb with an
> loff_t __user *ki_posp.
>
> I don't think it's worth worrying about growing kiocb, personally,
> but this seemed like the easiest way to make room for a new pointer.
The user offset pointer has absolutely no business in the the kiocb
itself - it is a io_uring concept which needs to go into the io_kiocb,
which has 14 bytes left in the last cache line in my build. It would
fit in very well there right next to the result and user pointer.
next prev parent reply other threads:[~2020-07-09 13:26 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-08 22:26 [PATCH 0/2] Remove kiocb ki_complete Matthew Wilcox (Oracle)
2020-07-08 22:26 ` [PATCH 1/2] fs: Abstract calling the kiocb completion function Matthew Wilcox (Oracle)
2020-07-08 22:37 ` Jens Axboe
2020-07-08 22:40 ` Matthew Wilcox
2020-07-08 22:50 ` Jens Axboe
2020-07-08 22:26 ` [PATCH 2/2] fs: Remove kiocb->ki_complete Matthew Wilcox (Oracle)
2020-07-08 22:38 ` Jens Axboe
2020-07-09 3:25 ` Jens Axboe
2020-07-09 5:23 ` kernel test robot
2020-07-08 22:33 ` [PATCH 0/2] Remove kiocb ki_complete Jens Axboe
2020-07-09 10:17 ` Christoph Hellwig
2020-07-09 11:10 ` Matthew Wilcox
2020-07-09 13:26 ` Christoph Hellwig [this message]
2020-07-09 13:32 ` Matthew Wilcox
2020-07-09 13:53 ` Jens Axboe
2020-07-09 13:37 ` Pavel Begunkov
2020-07-09 13:43 ` Matthew Wilcox
2020-07-09 13:49 ` Pavel Begunkov
2020-07-09 13:53 ` Matthew Wilcox
2020-07-09 13:59 ` Pavel Begunkov
2020-07-09 13:55 ` Jens Axboe
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