linux-ext4 - Re: [ext3] Changes to block device after an ext3 mount point has been remounted readonly

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Message-ID: <20100224165940.GM3687@quack.suse.cz>
Date:	Wed, 24 Feb 2010 17:59:41 +0100
From:	Jan Kara <jack@...e.cz>
To:	Camille Moncelier <pix@...life.org>
Cc:	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	ext4 development <linux-ext4@...r.kernel.org>,
	Jan Kara <jack@...e.cz>
Subject: Re: [ext3] Changes to block device after an ext3 mount point has
 been remounted readonly

On Wed 24-02-10 17:26:37, Camille Moncelier wrote:
> > Theoretically some pages may exist after rw=>ro remount
> > because of generic race between write/sync, And they will be written
> > in by writepage if page already has buffers. This not happen in ext4
> > because. Each time it try to perform writepages it try to start_journal
> > and this result in EROFS.
> > The race bug will be closed some day but new one may appear again.
> >
> > Let's be honest and change ext3 writepage like follows:
> > - check ROFS flag inside write page
> > - dump writepage's errors.
> >
> >
> I think I don't understand correctly your patch. For me it seems that
> when an ext3 filesystem is remounted ro, some data may not have been
> written to disk right ?
  I think that Dmitry was concerned about the fact that a process could
open a file and write to it after we synced the filesystem in
do_remount_sb().

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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