samba - Jun 2007 - samba not responding to linux __break_lease() call.

I am working on a distributed file system running on linux where I am trying
to add support for samba OpLocks and I am observing behavior that I do not
understand.

My understanding is that samba establishes a lease on a file and expects to
receive a signal when conditions change and samba must relinquish the
lease.  In my file system, when I detect a condition, possibly on another
node of my cluster, that requires samba to relinquish the lease, the file
system calls linux routine, __break_lease(), on the node where the samba
server has established the lease.  I would expect that the call to
__break_lease() would generate a signal that would then result in the samba
server making an fcntl() call to release the lease.  I clearly see the
__break_lease() calls occurring but then I observe a long period (45 seconds
the lease timeout period) where nothing happens.

I am running samba-3.0.24-3.fc6 on a 32 bit i686  (930 Mhz) machine with a
slightly modified linux 2.6.19.5.  Any help or insight would be greatly
appreciated.

- Robert Rappaport

On Fri, Jun 15, 2007 at 05:16:00PM -0400, Robert Rappaport
wrote:
> server making an fcntl() call to release the lease.  I clearly see the
> __break_lease() calls occurring but then I observe a long period (45
seconds
> the lease timeout period) where nothing happens.
"nothing happens" meaning exactly what? Is the signal being
delivered to the smbd process? If it is, then it is a
potential smbd problem. If it's not, there's not much you
can do about it.

Question: Are you implementing the full beauty of the
Windows oplock levels? Or "just" what the Linux Kernel does
right now? If I'm right then things like batch oplocks are
not supported by Linux right now.

I'm asking because if you want to support Windows clients
across your cluster you have two options: Use the Samba/ctdb
combo to get full Windows semantics or do the full Windows
semantics in the kernel. Naturally I'd vote for the ctdb
thing and only provide the minimum necessary to local
processes and NFS. The Windows semantics are quite tricky,
after 15 years of working with it we're still finding new
behaviour :-)

Volker
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