[Lustre-devel] Sub Tree lock ideas.

[Oleg Drokin]

Hello!

On Feb 3, 2009, at 10:01 AM, Nikita Danilov wrote:
>>    For the case of a different client stepping into area covered by
>> STL lock, this client would get STL lock's cookie and will start
>> present it for all subsequent
>>    operations (also a special flag meaning that the client is not
>> operating within STL).
> How is it determined that a given point in a namespace is covered by  
> an
> STL lock? E.g., client A holds an STL on /a, and client B accesses
> /a/b/c/f (where /a/b/c is a working directory of some process on B)?
> This looks especially problematic in the CMD case.

When client B looks up /a during its path traversal, it will get a  
lock cookie
of the STL lock and will start presenting it with further lookups.
If /a/b/c became a working dir of process B before STL on /a was  
granted, then
/a/b/c has a normal lock for client B and STL does not cover that  
subtree.
Also see other discussion on this topic here, since in the end we  
might end up
not implementing entire STL idea.

Bye,
     Oleg