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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
	io-uring@vger.kernel.org, Josh Triplett <josh@joshtriplett.org>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Stefan Metzmacher <metze@samba.org>
Subject: [PATCH v3 0/4] open/accept directly into io_uring fixed file table
Date: Sat, 21 Aug 2021 16:52:36 +0100	[thread overview]
Message-ID: <cover.1629559905.git.asml.silence@gmail.com> (raw)

Add an optional feature to open/accept directly into io_uring's fixed
file table bypassing the normal file table. Same behaviour if as the
snippet below, but in one operation:

sqe = prep_[open,accept](...);
cqe = submit_and_wait(sqe);
io_uring_register_files_update(uring_idx, (fd = cqe->res));
close((fd = cqe->res));

The idea in pretty old, and was brough up and implemented a year ago
by Josh Triplett, though haven't sought the light for some reasons.

The behaviour is controlled by setting sqe->file_index, where 0 implies
the old behaviour. If non-zero value is specified, then it will behave
as described and place the file into a fixed file slot
sqe->file_index - 1. A file table should be already created, the slot
should be valid and empty, otherwise the operation will fail.

we can't use IOSQE_FIXED_FILE to switch between modes, because accept
takes a file, and it already uses the flag with a different meaning.

since RFC:
 - added attribution
 - updated descriptions
 - rebased

since v1:
 - EBADF if slot is already used (Josh Triplett)
 - alias index with splice_fd_in (Josh Triplett)
 - fix a bound check bug

Pavel Begunkov (4):
  net: add accept helper not installing fd
  io_uring: openat directly into fixed fd table
  io_uring: hand code io_accept() fd installing
  io_uring: accept directly into fixed file table

 fs/io_uring.c                 | 129 +++++++++++++++++++++++++++++-----
 include/linux/socket.h        |   3 +
 include/uapi/linux/io_uring.h |   5 +-
 net/socket.c                  |  71 ++++++++++---------
 4 files changed, 157 insertions(+), 51 deletions(-)

-- 
2.32.0


             reply	other threads:[~2021-08-21 15:53 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-21 15:52 Pavel Begunkov [this message]
2021-08-21 15:52 ` [PATCH v3 1/4] net: add accept helper not installing fd Pavel Begunkov
2021-08-23 16:35   ` Jakub Kicinski
2021-08-21 15:52 ` [PATCH v3 2/4] io_uring: openat directly into fixed fd table Pavel Begunkov
2021-08-21 15:52 ` [PATCH v3 3/4] io_uring: hand code io_accept() fd installing Pavel Begunkov
2021-08-21 15:52 ` [PATCH v3 4/4] io_uring: accept directly into fixed file table Pavel Begunkov
2021-08-22  2:18 ` [PATCH v3 0/4] open/accept directly into io_uring " Jens Axboe
2021-08-23 19:13   ` Josh Triplett
2021-08-23 19:40     ` Jens Axboe
2021-08-24  9:48       ` Pavel Begunkov
2021-08-24 14:02         ` Jens Axboe
2021-08-24 14:43           ` Pavel Begunkov

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