From: Andrew Morton <akpm@osdl.org>
To: Daniel Phillips <phillips@arcor.de>
Cc: reiser@namesys.com, reiserfs-list@namesys.com,
linux-kernel@vger.kernel.org
Subject: Re: precise characterization of ext3 atomicity
Date: Thu, 4 Sep 2003 13:10:52 -0700 [thread overview]
Message-ID: <20030904131052.6ec6426d.akpm@osdl.org> (raw)
In-Reply-To: <200309042216.04121.phillips@arcor.de>
Daniel Phillips <phillips@arcor.de> wrote:
>
> On Thursday 04 September 2003 17:55, Andrew Morton wrote:
> > Hans Reiser <reiser@namesys.com> wrote:
> > > Is it correct to say of ext3 that it guarantees and only guarantees
> > > atomicity of writes that do not cross page boundaries?
> >
> > Yes.
>
> Is that just happenstance, or does Posix or similar mandate it?
Happenstance.
It's semi-trivial to do this in ext3. You'd open the file with O_ATOMIC
and a write() would either be completely atomic or would return -EFOO
without having written anything.
The thing which prevents this is the ranking order between journal_start()
and lock_page().
It's not trivial but also not too hard to change things so that
journal_start() can rank outside lock_page() - this would also offer some
CPU savings.
Can't say that I'm terribly motivated about the feature though.
next prev parent reply other threads:[~2003-09-04 20:28 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-04 14:20 Hans Reiser
2003-09-04 15:55 ` Andrew Morton
2003-09-04 15:59 ` Hans Reiser
2003-09-04 16:12 ` Andrew Morton
2003-09-04 16:25 ` Hans Reiser
2003-09-04 18:15 ` Mike Fedyk
2003-09-04 16:05 ` Antonio Vargas
2003-09-04 18:37 ` Hans Reiser
2003-09-04 19:12 ` Mike Fedyk
2003-09-04 21:03 ` Hans Reiser
2003-09-04 19:28 ` Andreas Dilger
2003-09-04 21:32 ` Hans Reiser
2003-09-04 22:03 ` Andreas Dilger
2003-09-05 13:47 ` Chris Mason
2003-09-09 13:09 ` Pavel Machek
2003-09-09 19:21 ` Gábor Lénárt
2003-09-09 19:43 ` Mike Fedyk
2003-09-04 20:16 ` Daniel Phillips
2003-09-04 20:10 ` Andrew Morton [this message]
2003-09-04 21:08 ` Daniel Phillips
2003-09-04 21:39 ` Hans Reiser
2003-09-04 21:59 ` Daniel Phillips
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