Date: Wed, 9 Jun 2004 17:38:56 -0700
From: Andrew Morton <akpm@osdl.org>
To: Chris Mason <mason@suse.com>
Cc: B.Zolnierkiewicz@elka.pw.edu.pl, axboe@suse.de, edt@aei.ca,
       linux-kernel@vger.kernel.org
Subject: Re: ide errors in 7-rc1-mm1 and later
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Chris Mason <mason@suse.com> wrote:
>
> On Wed, 2004-06-09 at 19:50, Andrew Morton wrote:
> > Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl> wrote:
> > >
> > > Does journal has checksum or some other protection against failure during
> > > writing journal to a disk?  If not than it still can be screwed even with
> > > ordered writes if we are unfortunate enough.  ;-)
> > 
> > A transaction is written to disk as two synchronous operations: write all
> > the data, wait on it, write the single commit block, wait on that.
> > 
> > If the commit block were to hit disk before the data then we have a window
> > in which poweroff+recovery would replay garbage into the filesystem.
> > 
> > So I think we have a bug in the current ext3 barrier implementation - we
> > need a blk_issue_flush() before submitting the buffer_ordered commit block.
> 
> The IDE barriers are both a pre and post flush.  If the commit block is
> ordered, before the commit block hits the disk we know all the blocks
> previously submitted are also on disk.
> 

Oh, OK.  Will the same apply to (for example) scsi?
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