Re: [dm-devel] dm-thinp bug

[Christoph Hellwig <hch infradead org>]

On Wed, Apr 27, 2011 at 09:27:37AM +0100, Joe Thornber wrote:
> On Tue, 2011-04-26 at 14:47 -0400, Christoph Hellwig wrote:
> > I can reproduce a bug in virtio triggered by running under dm-thinp by
> > just copying lots of files from my home directory into a freshly created
> > filesystem on dm-thinp.
> 
> Finally someone has tried using it!  I'll look into this today.

I actually used the earlier version you posted and didn't reproduce it
there.  I have a gut feeling it's related to barriers, as I probably
just did a basic ext3 test back then.

One thing that springs to mind is that both the thinp and multisnap
targets don't appear to support empty barriers (that is REQ_FLUSH
without a payload), because they don't set ti->num_flush_requests, but
I'm not sure that's related.