[sheepdog] [PATCH] sheep: remove block/unblock callbacks

[Christoph Hellwig]

On Wed, Jun 06, 2012 at 09:28:38PM +0800, Liu Yuan wrote:
> Yes, this patch only serialize the cluster requests on local node, but I
> think this is good enough. Sheepdog doesn't need to carry on the burden
> such as name collision detection, which could be handled very well
> (better) by the administration layer by serious users. Remove
> block/unblock logic is relatively difficult to understand and possibly
> risk the cluster to be blocked for ever (assume any bug that blocks the
> cluster but forget unblock it).
> 
> By removing it, we get much more (1 simpler code 2 remove deadlock risk)
> than lose (just leave the burden to upper layer).

Sheepdog needs to handle concurrent creation of VDIs, for some defintion
of handling - detecting the case and returning an error would be enough,
causing silent failures would not.

That why I said I like the approch, but issues like the one above need
to be carefully audited and fixed.