Re: [GIT PULL] io_uring updates for 5.14-rc1

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

On Tue, Jun 29, 2021 at 1:43 PM Jens Axboe <axboe@kernel.dk> wrote:
>
> - Support for mkdirat, symlinkat, and linkat for io_uring (Dmitry)

I pulled this, and then I unpulled it again.

I hate how makes the rules for when "putname()" is called completely
arbitrary and very confusing. It ends up with multiple cases of
something like

        error = -ENOENT;
        goto out_putnames;

that didn't exist before.

And worse still ends up being that unbelievably ugly hack with

        // On error `new` is freed by __filename_create, prevent extra freeing
        // below
        new = ERR_PTR(error);
        goto out_putpath;

that ends up intentionally undoing one of the putnames because the
name has already been used.

And none of the commits have acks by Al. I realize that he can
sometimes be a bit unresponsive, but this is just *UGLY*. And we've
had too many io_uring issues for me to just say "I'm sure it's fine".

I can see a few ways to at least de-uglify things:

 - Maybe we can make putname() just do nothing for IS_ERR_OR_NULL() names.

   We have that kind of rules for a number of path walking things,
where passing in an error pointer is fine. Things like
link_path_walk() or filename_lookup() act that way very much by
design, exactly to make it easy to handle error conditions.

 - callers of __filename_create() and similar thar eat the name (and
return a dentry or whatever) could then set the name to NULL, not as
part of the error handling, but unconditionally as a "it's been used".

So I think this is fixable.

But I'm *VERY* tired of io_uring being so buggy and doing "exciting"
things, and when it then starts affecting very core functionality and
I don't even see ack's from the one person who understands all of
that, I put my foot down.

No more flaky io_uring pulls. Give me the unambiguously good stuff,
not this kind of unacked ugly stuff.

               Linus