linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>,
	Pavel Begunkov <asml.silence@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [git pull] iov_iter fixes
Date: Fri, 10 Sep 2021 18:48:34 +0000	[thread overview]
Message-ID: <YTuogsGTH5pQLKo7@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <CAHk-=wjWQtXmtOK9nMdM68CKavejv=p-0B81WazbjxaD-e3JXw@mail.gmail.com>

On Fri, Sep 10, 2021 at 10:31:00AM -0700, Linus Torvalds wrote:
> 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?

I think that sizeof(struct bio_vec) != sizeof(struct iovec):
struct bio_vec {
        struct page     *bv_page;
	unsigned int    bv_len;
	unsigned int    bv_offset;
};
takes 3 words on 32bit boxen.
struct iovec
{
        void __user *iov_base;  /* BSD uses caddr_t (1003.1g requires void *) */
	__kernel_size_t iov_len; /* Must be size_t (1003.1g) */
};
takes 2 words on 32bit boxen.

  parent reply	other threads:[~2021-09-10 18:50 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-09  4:22 [git pull] iov_iter fixes Al Viro
2021-09-09 19:37 ` Linus Torvalds
2021-09-09 21:19   ` Jens Axboe
2021-09-09 21:39     ` Jens Axboe
2021-09-09 21:56       ` Linus Torvalds
2021-09-09 22:21         ` Jens Axboe
2021-09-09 22:56           ` Linus Torvalds
2021-09-10  1:35             ` Jens Axboe
2021-09-10  2:43               ` Jens Axboe
2021-09-10  2:48               ` Al Viro
2021-09-10  3:06                 ` Jens Axboe
2021-09-10  3:15                   ` Al Viro
2021-09-10  3:23                     ` Jens Axboe
2021-09-10  3:24                     ` Al Viro
2021-09-10  3:28                       ` Jens Axboe
2021-09-13 15:29                 ` David Laight
2021-09-09 21:42     ` Dave Chinner
2021-09-10  2:57     ` Al Viro
2021-09-10  3:05       ` Jens Axboe
2021-09-10  3:11         ` Al Viro
2021-09-10  3:22           ` Jens Axboe
2021-09-10  3:27             ` Al Viro
2021-09-10  3:30               ` Jens Axboe
2021-09-10  3:36                 ` Al Viro
2021-09-10 13:57                   ` Jens Axboe
2021-09-10 14:42                     ` Al Viro
2021-09-10 15:08                       ` Jens Axboe
2021-09-10 15:32                         ` Al Viro
2021-09-10 15:36                           ` Jens Axboe
2021-09-10 15:04                     ` Jens Axboe
2021-09-10 16:06                       ` Jens Axboe
2021-09-10 16:44                         ` Linus Torvalds
2021-09-10 16:56                         ` Al Viro
2021-09-10 16:58                           ` Linus Torvalds
2021-09-10 17:26                             ` Jens Axboe
2021-09-10 17:31                               ` Linus Torvalds
2021-09-10 17:32                                 ` Jens Axboe
2021-09-10 18:48                                 ` Al Viro [this message]
2021-09-10 19:04                                   ` Linus Torvalds
2021-09-10 19:10                                     ` Linus Torvalds
2021-09-10 19:10                                   ` Jens Axboe
2021-09-10 17:04                           ` Jens Axboe
2021-09-09 22:54   ` Pavel Begunkov
2021-09-09 22:57     ` Pavel Begunkov
2021-09-09 23:14   ` Pavel Begunkov
2021-09-09 20:03 ` pr-tracker-bot

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YTuogsGTH5pQLKo7@zeniv-ca.linux.org.uk \
    --to=viro@zeniv.linux.org.uk \
    --cc=asml.silence@gmail.com \
    --cc=axboe@kernel.dk \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).