XFS hung on 2.6.33.3 kernel

[Christoph Hellwig]

On Sun, Jul 18, 2010 at 11:20:33AM +1000, Dave Chinner wrote:
> So, back to the situation with the WARN_ON(). You're running
> applications that are doing something that:
> 
> 	a) is not supported;
> 	b) compromises data integrity guarantees;
> 	c) is not reliably reported; and
> 	d) might be causing hangs
> 
> Right now I'm not particularly inclined to dig into this further;
> it's obvious the applications are doing something that is not
> supported (by XFS or the generic page cache code), so this is the
> first thing you really need to care about getting fixed if you value
> your backups...

While it's slightly crazy it's also a pretty easy way for users to shoot
themselve in their feet.  Unlike the generic filesystems with their
simplistic i_mutex locking we have a way to assure this works properly
in XFS with the shared/exclusive iolock, so I'm willing to look into
this further.

Ilia, would you be willing to test patches for this?