Date: Tue, 15 Jun 2010 09:19:43 +1000
From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
       viro@ZenIV.linux.org.uk, josef@redhat.com, jeffmerkey@gmail.com
Subject: Re: [PATCH 1/5] fsfreeze: Prevent emergency thaw from looping
 infinitely
Message-ID: <20100614231943.GH6590@dastard>
References: <1276154395-24766-1-git-send-email-david@fromorbit.com>
 <1276154395-24766-2-git-send-email-david@fromorbit.com>
 <20100614151815.GA32354@infradead.org>
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On Mon, Jun 14, 2010 at 11:18:15AM -0400, Christoph Hellwig wrote:
> On Thu, Jun 10, 2010 at 05:19:50PM +1000, Dave Chinner wrote:
> > Return -EINVAL when the filesystem is already unfrozen to avoid this
> > problem.
> 
> 
> This includes some additional changes in addition to the description,
> and at least one of them seems incorrect.
> 
> > -	error = 0;
> > -	if (--bdev->bd_fsfreeze_count > 0)
> > +	if (!sb)
> >  		goto out;
> >  
> > -	if (!sb)
> > +	error = 0;
> > +	if (--bdev->bd_fsfreeze_count > 0)
> >  		goto out;
> 
> Here you reorder the sb check to be before the counter decrement.  But
> we do support calling freeze_bdev on a device without a superblock, and
> you would leak bd_fsfreeze_count for that case and wrongly return
> -EINVAL on unthaw for these now.

Ok, will fix it.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com
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