From: Jan Kara <jack@suse.cz>
To: Theodore Tso <tytso@mit.edu>
Cc: Andreas Dilger <adilger@sun.com>,
Ric Wheeler <rwheeler@redhat.com>,
Christian Fischer <Christian.Fischer@easterngraphics.com>,
linux-ext4@vger.kernel.org
Subject: Re: Enable asynchronous commits by default patch revoked?
Date: Wed, 26 Aug 2009 18:02:31 +0200 [thread overview]
Message-ID: <20090826160231.GA28867@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <20090825001554.GN17684@mit.edu>
> On Mon, Aug 24, 2009 at 05:43:36PM -0600, Andreas Dilger wrote:
> > Without transaction checksums waiting on all of the blocks together
> > is NOT safe. If the commit record is on disk, but the rest of the
> > transaction's blocks are not then during replay it may cause garbage
> > to be written from the journal into the filesystem metadata.
>
> Yes, I *said* that we can only wait on all of the blocks together with
> the commit record when doing journal checksums. Sorry if I didn't
> make that clear enough.
I suppose we talk about the case when write caches are turned off and
we use barrier=0 (because case barrier=1 does not really care about when
we wait for the blocks from the correctness POV - at least according to
Documentation/block/barrier.txt). In that case, you have to wait for
*data* blocks before writing the commit block because you have no
checksumming of those...
Honza
--
Jan Kara <jack@suse.cz>
SuSE CR Labs
next prev parent reply other threads:[~2009-08-26 16:02 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200908241033.10527.Christian.Fischer@easterngraphics.com>
2009-08-24 13:34 ` Enable asynchronous commits by default patch revoked? Theodore Tso
2009-08-24 18:31 ` Andreas Dilger
2009-08-24 18:37 ` Ric Wheeler
2009-08-24 20:10 ` Theodore Tso
2009-08-24 20:28 ` Ric Wheeler
2009-08-24 22:07 ` Theodore Tso
2009-08-24 22:12 ` Ric Wheeler
2009-08-24 23:28 ` Theodore Tso
2009-08-24 23:43 ` Andreas Dilger
2009-08-25 0:15 ` Theodore Tso
2009-08-25 17:52 ` Andreas Dilger
2009-08-25 18:07 ` Ric Wheeler
2009-08-25 21:11 ` Theodore Tso
2009-08-26 9:50 ` Andreas Dilger
2009-08-26 13:14 ` Theodore Tso
2009-08-26 22:00 ` Andreas Dilger
2009-08-26 22:55 ` Theodore Tso
2009-08-25 18:21 ` Ric Wheeler
2009-08-26 16:02 ` Jan Kara [this message]
2009-08-24 22:46 ` Andreas Dilger
2009-08-24 23:52 ` Theodore Tso
2009-09-02 14:48 ` Tom Vier
2009-09-02 15:03 ` Theodore Tso
2009-08-24 21:28 ` Andreas Dilger
2009-08-25 6:16 ` Christian Fischer
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