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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 10 Sep 2021 10:31:00 -0700
Message-ID: <CAHk-=wjWQtXmtOK9nMdM68CKavejv=p-0B81WazbjxaD-e3JXw@mail.gmail.com>
Subject: Re: [git pull] iov_iter fixes
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Pavel Begunkov <asml.silence@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
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On Fri, Sep 10, 2021 at 10:26 AM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 9/10/21 10:58 AM, Linus Torvalds wrote:
> > On Fri, Sep 10, 2021 at 9:56 AM Al Viro <viro@zeniv.linux.org.uk> wrote:
> >>
> >> What's the point of all those contortions, anyway?  You only need it for
> >> iovec case; don't mix doing that and turning it into flavour-independent
> >> primitive.
> >
> > Good point, making it specific to iovec only gets rid of a lot of
> > special cases and worries.
> >
> > This is fairly specialized, no need to always cater to every possible case.
>
> Alright, split into three patches:
>
> https://git.kernel.dk/cgit/linux-block/log/?h=iov_iter

That looks sane to me.

Please add some comment about how that

        i->iov -= state->nr_segs - i->nr_segs;

actually is the right thing for all the three cases (iow how 'iov',
'kvec' and 'bvec' all end up having a union member that acts the same
way).

But yeah, I like how the io_uring.c code looks better this way too.

Al, what do you think?

              Linus