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From: Miklos Szeredi <miklos@szeredi.hu>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Vivek Goyal <vgoyal@redhat.com>,
	Dharmendra Singh <dharamhans87@gmail.com>,
	Bernd Schubert <bschubert@ddn.com>
Subject: Re: [RFC PATCH] vfs: allow ->atomic_open() on positive
Date: Fri, 20 May 2022 08:44:35 +0200	[thread overview]
Message-ID: <CAJfpegu4Pa+XUnooZn4g9OCK9Kyh9UTSROvah=E57zvg=+53Ww@mail.gmail.com> (raw)
In-Reply-To: <YocT+9pebi3ZBHdn@zeniv-ca.linux.org.uk>

On Fri, 20 May 2022 at 06:07, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Thu, May 19, 2022 at 04:43:58PM +0200, Miklos Szeredi wrote:
> > Hi Al,
> >
> > Do you see anything bad with allowing ->atomic_open() to take a positive dentry
> > and possibly invalidate it after it does the atomic LOOKUP/CREATE+OPEN?
> >
> > It looks wrong not to allow optimizing away the roundtrip associated with
> > revalidation when we do allow optimizing away the roundtrip for the initial
> > lookup in the same situation.
>
> Details, please - what will your ->atomic_open() do in that case?

It will do an open-by-name or create-and-open depending on the flags.
It will return whether the file was created or not.

If created, then the old positive is obviously stale, so it will be
invalidated and a new one allocated.

If not created, then check whether it's the same inode (same as in
->d_revalidate()) and if not, invalidate & allocate new dentry.

Thanks,
Miklos

      reply	other threads:[~2022-05-20  6:44 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-19 14:43 [RFC PATCH] vfs: allow ->atomic_open() on positive Miklos Szeredi
2022-05-19 20:09 ` Vivek Goyal
2022-05-19 20:43   ` Bernd Schubert
2022-05-19 20:50     ` Vivek Goyal
2022-05-20  6:48   ` Miklos Szeredi
2022-05-20  4:07 ` Al Viro
2022-05-20  6:44   ` Miklos Szeredi [this message]

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