[Sheepdog] Some setattr/getattr strangeness

[MORITA Kazutaka]

At Wed, 12 Oct 2011 16:07:41 +0100,
Chris Webb wrote:
> 
> MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp> writes:
> 
> > Chris Webb wrote:
> > > I'm guessing that what's really going on here is that the setattr
> > > operation happens asynchronously and hasn't finished by the time the
> > > command exits and we do the getattr?
> > 
> > Sorry, I couldn't reproduce this.  "collie vdi setattr" should be a
> > synchronous operation.  Were there node membership changes (node
> > join/left) during vdi attribute operations?
> 
> Hi. No, there weren't node changes, but I think there may have been multiple
> attempts to claim the lock with setattr -x at the same time. (All but the
> first are supposed to fail, of course.) This is definitely atomic in the
> correct way isn't it?

Yes, as long as setattr -x is run on the same machine.  Note that
Sheepdog object storage doesn't allow concurrent accesses from
multiple machines.

> 
> I'll try to cook up a short recipe that reproduces the symptoms in a line of
> shell rather than going through our whole management system!

Thanks, it would be really helpful!

Kazutaka