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

[Sunil Mushran]

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.