xfs_growfs causing "Metadata corruption detected at xfs_agf_read_verify"

[Richard W.M. Jones]

On Thu, Mar 17, 2016 at 05:55:52PM -0500, Eric Sandeen wrote:
> On 3/17/16 5:48 PM, Richard W.M. Jones wrote:
> > 
> > With recent kernels (or maybe xfsprogs?) we've noticed strange
> > filesystem corruption after using xfs_growfs.
> > 
> > Examples:
> > 
> > https://bugzilla.redhat.com/show_bug.cgi?id=1315895 (on aarch64)
> > https://www.redhat.com/archives/libguestfs/2016-March/msg00113.html (x86_64)
> > https://rwmj.wordpress.com/2015/11/04/virt-builder-fedora-23-image/#comment-15668 (x86_64)
> > 
> > Do these errors look familiar?  I don't yet have a simple test case,
> > still working on that.
> 
> try:
> http://oss.sgi.com/pipermail/xfs/2016-March/047683.html

I've tried this patch now, but I still can't get a solid reproducer
(one that doesn't involve using aarch64).

I just tried to create a filesystem on kernel 4.6.0, grow it on 4.6.0,
then copy it to another machine with 4.4.4.  However that didn't
reproduce the bug, so I couldn't verify if the patch fixes the bug.
(Maybe 4.4.4 is too new?)

Can you help me to understand under what circumstances this bug would
appear, as far as you understand what's happening?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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