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From: Christoph Hellwig on 14 Jun 2010 11:20
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.

> error = thaw_super(sb);
> - if (error) {
> + if (error)
> bdev->bd_fsfreeze_count++;
> - mutex_unlock(&bdev->bd_fsfreeze_mutex);
> - return error;
> - }

Ok, useful cleanup.

> out:
> mutex_unlock(&bdev->bd_fsfreeze_mutex);
> - return 0;
> + return error;

And this is the actual fix of course, also looks good.

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From: Dave Chinner on 14 Jun 2010 19:30
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(a)fromorbit.com
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