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From: Jens Axboe <axboe@kernel.dk>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: io-uring@vger.kernel.org
Subject: Re: [PATCH 2/5] io_uring: add support for IORING_OP_URING_CMD
Date: Wed, 27 Jan 2021 19:19:25 -0700	[thread overview]
Message-ID: <f8576940-5441-1355-c09e-db60ad0ac889@kernel.dk> (raw)
In-Reply-To: <67627096-6d30-af3a-9545-1446909a38c4@kernel.dk>

>> Assuming that I got that right, that means that the pdu information
>> doesn't actually go all the way to the end of the sqe, which currently
>> is just a bunch of padding.  Was that intentional, or does this mean
>> that io_uring_pdu could actually be 8 bytes longer?
> 
> Also correct. The reason is actually kind of stupid, and I think we
> should just fix that up. struct io_uring_cmd should fit within the first
> cacheline of io_kiocb, to avoid bloating that one. But with the members
> in there, it ends up being 8 bytes too big, if we grab those 8 bytes.
> What I think we should do is get rid of ->done, and just have drivers
> call io_uring_cmd_done() instead. We can provide an empty hook for that.
> Then we can reclaim the 8 bytes, and grow the io_uring_cmd to 56 bytes.

Pushed out that version:

https://git.kernel.dk/cgit/linux-block/log/?h=io_uring-fops.v2

which gives you the full 56 bytes for the payload command.

-- 
Jens Axboe


  reply	other threads:[~2021-01-28  2:20 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-27 21:25 [PATCHSET RFC 0/5] file_operations based io_uring commands Jens Axboe
2021-01-27 21:25 ` [PATCH 1/5] fs: add file_operations->uring_cmd() Jens Axboe
2021-01-27 21:25 ` [PATCH 2/5] io_uring: add support for IORING_OP_URING_CMD Jens Axboe
2021-01-28  0:38   ` Darrick J. Wong
2021-01-28  1:45     ` Jens Axboe
2021-01-28  2:19       ` Jens Axboe [this message]
2021-02-20  3:57         ` Stefan Metzmacher
2021-02-20 14:50           ` Jens Axboe
2021-02-20 16:45             ` Jens Axboe
2021-02-22 20:04               ` Stefan Metzmacher
2021-02-22 20:14                 ` Jens Axboe
2021-02-23  8:14                   ` Stefan Metzmacher
2021-02-23 13:21                     ` Pavel Begunkov
2021-01-27 21:25 ` [PATCH 3/5] block: wire up support for file_operations->uring_cmd() Jens Axboe
2021-01-27 21:25 ` [PATCH 4/5] block: add example ioctl Jens Axboe
2021-01-27 21:25 ` [PATCH 5/5] net: wire up support for file_operations->uring_cmd() Jens Axboe

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