[sheepdog] Is it necessary for outstanding io block leave/join event?

[Christoph Hellwig]

On Thu, May 17, 2012 at 09:56:15AM +0800, Liu Yuan wrote:
> This assumption seems not necessary, at least to Farm, where I/O will
> always be routed into objects in the working directory.
> 
> Let outstanding IO blocks confchg will risk both dead lock and live lock.

It also has rather direct performance consequences.

> I think both recovery code and any assumptions need to be revisited and
> possibly this is a long term issue.

One question is if we should support the simple store much longer.  Not
just in this regard farm has a lot of advantages, while I'm not sure
what the added benefit of the simple store is.