Re: [PATCH 5/7] namei: clean up do_symlinkat retry logic

[Linus Torvalds <torvalds@linux-foundation.org>]

On Mon, Jul 12, 2021 at 5:37 AM Dmitry Kadashev <dkadashev@gmail.com> wrote:
>
> +
> +int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
> +{
> +       int error;
> +
> +       if (IS_ERR(from)) {
> +               error = PTR_ERR(from);
> +               goto out;
>         }
> -out_putnames:
> +
> +       error = symlinkat_helper(from, newdfd, to, 0);
> +       if (retry_estale(error, 0))
> +               error = symlinkat_helper(from, newdfd, to, LOOKUP_REVAL);
> +
> +out:
>         putname(to);
>         putname(from);
>         return error;

So here you moved that part that was outside the retry loop into the
caller. Except it's very ugly and keeps the goto mess.

So I'd suggest either keep it as a nested if - avoiding the goto - or
like in the previous patch, do that "we can do this test twice" with a
big commit message note about why it's ok.

Because it _is_ ok to repeat the test inside the retry_estale, and
'from' won't have changed (and won't have been -ESTALE in the first
place).

Looking at the pattern of this and the previous one, I think just
repeating the test is what generates the cleanest end result.

               Linus