Re: [RFC 0/4] open/accept directly into io_uring fixed file table

[Hao Xu]

在 2021/7/7 下午7:39, Pavel Begunkov 写道:
> Implement an old idea allowing open/accept io_uring requests to register
> a newly created file as a io_uring's fixed file instead of placing it
> into a task's file table. The switching is encoded in io_uring's SQEs
> by setting sqe->buf_index/file_index, so restricted to 2^16-1. Don't
> think we need more, but may be a good idea to scrap u32 somewhere
> instead.
>
>  From the net side only needs a function doing __sys_accept4_file()
> but not installing fd, see 2/4.
>
> Only RFC for now, the new functionality is tested only for open yet.
> I hope we can remember the author of the idea to add attribution.
Great feature! I believe this one leverages linked sqes, we may need to
remind users to be careful when they use this feature in shared sqthread
mode since linked sqes may be splited.
> Pavel Begunkov (4):
>    io_uring: allow open directly into fixed fd table
>    net: add an accept helper not installing fd
>    io_uring: hand code io_accept()' fd installing
>    io_uring: accept directly into fixed file table
>
>   fs/io_uring.c                 | 113 +++++++++++++++++++++++++++++-----
>   include/linux/socket.h        |   3 +
>   include/uapi/linux/io_uring.h |   2 +
>   net/socket.c                  |  71 +++++++++++----------
>   4 files changed, 138 insertions(+), 51 deletions(-)