On Sat, 23 Nov 2024 at 04:06, Christian Brauner <brauner@xxxxxxxxxx> wrote:
>
> So just to clarify when that issue was brought up I realized that the
> cred bump was a big deal for overlayfs but from a quick grep I didn't
> think for any of the other cases it really mattered that much.
Oh, I agree. It's probably not really a performance issue anywhere
else. I don't think this has really ever come up before.
So my "please convert everything to one single new model" is not
because I think that would help performance, but because I really hate
having two differently flawed models when I think one would do.
We have other situations where we really do have two or more different
interfaces for the "same" thing, with very special rules: things like
fget() vs fget_raw() vs fget_task() (and similar issues wrt fdget).
But I think those other situations have more _reason_ for them.
The whole "override_creds()" thing is _already_ such a special
operation, that I hate seeing two subtly different versions of the
interface, both with their own quirks.
Because the old interface really isn't some "perfectly tailored"
thing. Yes, the performance implications were a surprise to me and I
hadn't seen that before, but the "refcounting isn't wonderful" was
_not_ really a big surprise at all.
Linus
