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Date:   Wed, 12 Aug 2020 09:29:09 +0100
From:   David Howells <>
To:     Miklos Szeredi <>
        Linus Torvalds <>,
        linux-fsdevel <>,
        Al Viro <>, Karel Zak <>,
        Jeff Layton <>,
        Miklos Szeredi <>,
        Nicolas Dichtel <>,
        Christian Brauner <>,
        Lennart Poettering <>,
        Linux API <>,
        Ian Kent <>,
        LSM <>,
        Linux Kernel Mailing List <>
Subject: Re: file metadata via fs API (was: [GIT PULL] Filesystem Information)

Miklos Szeredi <> wrote:

> Worried about performance?  Io-uring will allow you to do all those
> five syscalls (or many more) with just one I/O submission.

io_uring isn't going to help here.  We're talking about synchronous reads.
AIUI, you're adding a couple more syscalls to the list and running stuff in a
side thread to save the effort of going in and out of the kernel five times.
But you still have to pay the set up/tear down costs on the fds and do the
pathwalks.  io_uring doesn't magically make that cost disappear.

io_uring also requires resources such as a kernel accessible ring buffer to
make it work.

You're proposing making everything else more messy just to avoid a dedicated
syscall.  Could you please set out your reasoning for that?


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