file metadata via fs API (was: [GIT PULL] Filesystem Information)

[David Howells]

Miklos Szeredi <miklos at szeredi.hu> 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?

David