[Linux-cluster] DLM user API for blocking AST

[David Teigland]

> > As a workaround to avoid an unwanted bast callback after a completion, I
> > wonder if you could make a no-op call with NULL astaddr/astarg to prevent
> > any further callback using those?
> 
> I assume that what you call a no-op is a lock conversion towards the same 
> mode as before, correct?

That should work.

> Then I think for this to work we need the second assumption I made, ie. 
> the kernel should not deliver the bast event to userland after it 
> delivered the cast for the last conversion.

The suggestion just depended on clearing on the astaddr/astarg values in
the kernel (which will itself have some effect on callbacks being sent or
not).  I hoped that might be a way to avoid analyzing callback ordering.

Dave