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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>,
	[email protected], Josh Triplett <[email protected]>
Cc: "David S . Miller" <[email protected]>,
	Jakub Kicinski <[email protected]>,
	[email protected], [email protected],
	Stefan Metzmacher <[email protected]>
Subject: [PATCH v4 0/4] open/accept directly into io_uring fixed file table
Date: Wed, 25 Aug 2021 12:25:43 +0100	[thread overview]
Message-ID: <[email protected]> (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 = io_uring_[open|accept]_prep();
io_uring_submit(sqe);
// ... once we get a CQE back
io_uring_register_files_update(uring_idx, (fd = cqe->res));
close((fd = cqe->res));

The idea is old, and was brough up and implemented a year ago by
Josh Triplett, though haven't sought the light.

The behaviour is controlled by setting sqe->file_index, where 0 implies
the old behaviour using normal file tables. 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.

note: IOSQE_FIXED_FILE can't be used as a mode switch, because accept
takes a file, and it already uses the flag with a different meaning.

v2, since RFC:
 - added attribution
 - updated descriptions
 - rebased

v3:
 - EBADF if slot is already used (Josh Triplett)
 - alias index with splice_fd_in (Josh Triplett)
 - fix a bound check bug

v4:
 - separate u32 fields to internally store indexes (Jens, Josh)

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                 | 115 +++++++++++++++++++++++++++++-----
 include/linux/socket.h        |   3 +
 include/uapi/linux/io_uring.h |   5 +-
 net/socket.c                  |  71 +++++++++++----------
 4 files changed, 143 insertions(+), 51 deletions(-)

-- 
2.32.0


             reply	other threads:[~2021-08-25 11:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-25 11:25 Pavel Begunkov [this message]
2021-08-25 11:25 ` [PATCH v4 1/4] net: add accept helper not installing fd Pavel Begunkov
2021-08-25 12:32   ` David Miller
2021-08-25 11:25 ` [PATCH v4 2/4] io_uring: openat directly into fixed fd table Pavel Begunkov
2021-08-25 11:25 ` [PATCH v4 3/4] io_uring: hand code io_accept() fd installing Pavel Begunkov
2021-08-25 11:25 ` [PATCH v4 4/4] io_uring: accept directly into fixed file table Pavel Begunkov
2021-08-25 15:00 ` [PATCH v4 0/4] open/accept directly into io_uring " Jens Axboe

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