[Ocfs2-devel] DLM Questions

[Jim Wayda (Stellus)]

I am interested in using a DLM for my user mode application and have been examining the ocfs2 DLM. I have been experimenting with the o2dlm_test code and have noticed an issue with the trylock command. When I start the o2dlm code with no options, it is operating in classic mode and is using /dlm.


1.       On node 1 and node 2  I issue the command "register test".


2.       On node 1 I issue the command "lock ex mylock" and the operation succeeds.


3.       On node 2 I issue the command "trylock ex mylock" and the operation fails as expected.


4.       On node 1, I then unlock by issuing the command "unlock mylock" and the operation succeeds.


5.       On node 2 I issue the command "trylock ex mylock" and the operation fails. This seems to be an error. The operation should succeed.

Note that if I try the same operations shown above with o2dlm_test invoked with the -u option which causes it to use fsdlm, I don't see the error in step 5 above. Everything works as expected.

It is also my understanding from examining the code that when using /dlm (this mode is referred to as "classic" in the source code), blocking ASTs are supported, but when using fsdlm blocking operations are not supported. Is this a correct understanding?

In the tests that I am running I am using the DLM with a two node ocfs2 cluster, but in my final design I want to remove the DLM code from the file system and use it in another application. Is this feasible?

Who is currently maintaining the DLM code?

Thanks,
-jim
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