[Ocfs2-devel] [PATCH] ocfs2/dlm: queue ast in lockres->spinlock

[Wengang Wang]

On 10-11-30 21:33, Sunil Mushran wrote:
> On 11/30/2010 06:52 PM, Wengang Wang wrote:
> >First I have to say that the scenario is in my thought only, no tcpdump
> >shows that. Only the node C wanting a PR is the truth from the vmcore.
> >
> >Let's consider this situation:
> >
> >The create lock(CL) is for a PR;
> >the up convert(UC) is PR->EX;
> >there is an existing PR granted for another node(say node D) before the UC comes
> >
> >The UC comes. Because of the existing PR, the UC lock is moved to converting list.
> >dlm_thread takes care it later.
> >The CL comes. no conflict found(see dlm_can_grant_new_lock, convert_type not
> >checked there). so it's not added to blocked list.
> >
> >Seems the above scenario can trigger a BAST before AST.
> 
> dlm_can_grant_new_lock() should be looking at convert_type also and
> add the lock to the blocked list in this case.
> 
> This is not just to plug this hole but is as per the spec.
So you meant o2dlm is (should be) implementing fair locking? Anywhere I
can take a look at the spec?

regards,
wengang.