From: Josh Triplett <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH WIP 0/3] Support userspace-selected fds
Date: Wed, 4 Mar 2020 06:35:48 -0800 [thread overview]
Message-ID: <20200304143548.GA407676@localhost> (raw)
Prototype of the proposal I made at
https://lore.kernel.org/io-uring/20200211223235.GA25104@localhost/ . See
also the discussion at
https://twitter.com/josh_triplett/status/1235004009502494721 .
The first patch is independent of the other two; it allows reserving
file descriptors below a certain minimum for userspace-selected fd
allocation only.
The second patch implements userspace-selected fd allocation for
openat2, introducing a new O_SPECIFIC_FD flag and an fd field in struct
open_how. In io_uring, this allows sequences like openat2/read/close
without waiting for the openat2 to complete. Multiple such sequences can
overlap, as long as each uses a distinct file descriptor.
The third patch adds userspace-selected fd allocation to pipe2 as well.
I did this partly as a demonstration of how simple it is to wire up
O_SPECIFIC_FD support for a new fd-allocating system call, and partly in
the hopes that this may make it more useful to wire up io_uring support
for pipe2 in the future.
Josh Triplett (3):
fs: Support setting a minimum fd for "lowest available fd" allocation
fs: openat2: Extend open_how to allow userspace-selected fds
fs: pipe2: Support O_SPECIFIC_FD
fs/fcntl.c | 2 +-
fs/file.c | 62 ++++++++++++++++++++++++++++----
fs/io_uring.c | 2 +-
fs/open.c | 6 ++--
fs/pipe.c | 15 +++++---
include/linux/fcntl.h | 5 +--
include/linux/fdtable.h | 1 +
include/linux/file.h | 3 ++
include/uapi/asm-generic/fcntl.h | 4 +++
include/uapi/linux/openat2.h | 2 ++
include/uapi/linux/prctl.h | 4 +++
kernel/sys.c | 10 ++++++
12 files changed, 100 insertions(+), 16 deletions(-)
--
2.25.1
next reply other threads:[~2020-03-04 14:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-04 14:35 Josh Triplett [this message]
2020-03-04 14:53 ` [PATCH WIP 1/3] fs: Support setting a minimum fd for "lowest available fd" allocation Josh Triplett
2020-03-04 14:53 ` [PATCH WIP 2/3] fs: openat2: Extend open_how to allow userspace-selected fds Josh Triplett
2020-03-04 14:53 ` [PATCH WIP 3/3] fs: pipe2: Support O_SPECIFIC_FD Josh Triplett
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