From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
Mikhail Malygin <m.malygin@yadro.com>,
Christoph Hellwig <hch@lst.de>
Cc: Alexander Buev <a.buev@yadro.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
"linux@yadro.com" <linux@yadro.com>
Subject: Re: [PATCH 0/3] implement direct IO with integrity
Date: Thu, 28 Oct 2021 18:11:26 +0100 [thread overview]
Message-ID: <e44e0928-bc01-06df-4bd7-cb120efeed50@gmail.com> (raw)
In-Reply-To: <bc0dc601-8e5a-800a-e3c4-d2dfdabb96fb@kernel.dk>
On 10/28/21 17:22, Jens Axboe wrote:
> On 10/28/21 9:56 AM, Pavel Begunkov wrote:
>> On 10/28/21 16:50, Jens Axboe wrote:
>>> On 10/28/21 9:44 AM, Mikhail Malygin wrote:
>>>> Thanks for the feedback, we’ll submit and updated version of the series.
>>>>
>>>> The only question is regarding uapi: should we add a separate opcodes
>>>> for read/write or use existing opcodes with the flag in the
>>>> io_uring_sqe.rw_flags field?
>>>>
>>>> The flag was discussed in the another submission, where it was
>>>> considered to be a better approach over opcodes:
>>>> https://patchwork.kernel.org/project/linux-block/patch/20200226083719.4389-2-bob.liu@oracle.com/
>>>
>>> Separate opcodes is, at least to me, definitely the way to go. Just
>>> looking at the code needing to tap into weird spots for PI is enough to
>>> make that call. On top of that, it also allows you to cleanly define
>>> this command and (hopefully?) avoid that weirdness with implied PI in
>>> the last iovec.
>>
>> Reminds me struggles with writing encoded data to btrfs. I believe
>> Omar did go for RWF_ENCODED flag, right?
>
> Exactly the same problem, yes. It ends up being pretty miserable, and
> there's no reason to go through that misery when we're not bound by only
> passing in an iovec.
I agree that a new opcode is better, at least we can keep the overhead
out of the common path, but RWF_ENCODED was having similar problems
(e.g. passing metadata in iov), so that's interesting why RWF was chosen
in the end. Is it only to support readv/writev(2) or something else?
--
Pavel Begunkov
next prev parent reply other threads:[~2021-10-28 17:13 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-28 11:24 [PATCH 0/3] implement direct IO with integrity Alexander V. Buev
2021-10-28 11:24 ` [PATCH 1/3] block: bio-integrity: add PI iovec to bio Alexander V. Buev
2021-10-28 15:16 ` Christoph Hellwig
2021-10-29 0:11 ` Chaitanya Kulkarni
2021-10-29 4:27 ` Martin K. Petersen
2021-10-29 10:59 ` Alexander V. Buev
2021-10-29 8:40 ` kernel test robot
2021-10-29 8:53 ` kernel test robot
2021-10-29 9:48 ` kernel test robot
2021-10-28 11:24 ` [PATCH 2/3] block: io_uring: add IO_WITH_PI flag to SQE Alexander V. Buev
2021-10-28 11:24 ` [PATCH 3/3] block: fops: handle IOCB_USE_PI in direct IO Alexander V. Buev
2021-10-28 15:17 ` Christoph Hellwig
2021-10-29 9:04 ` kernel test robot
2021-10-28 15:13 ` [PATCH 0/3] implement direct IO with integrity Jens Axboe
2021-10-28 15:18 ` Christoph Hellwig
2021-10-28 15:20 ` Jens Axboe
2021-10-28 15:44 ` Mikhail Malygin
2021-10-28 15:50 ` Jens Axboe
2021-10-28 15:56 ` Pavel Begunkov
2021-10-28 16:22 ` Jens Axboe
2021-10-28 17:11 ` Pavel Begunkov [this message]
2021-10-28 17:45 ` Jens Axboe
2021-10-29 3:39 ` Martin K. Petersen
2021-10-28 15:25 ` Jens Axboe
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