oplock_break problem (PR#20285)

[Jeremy Allison]

Jay.Anderson at dw.deere.com wrote:

> I believe the problem that occurs is that oplocks are left hanging on
> the server, and are never removed.  After a period of time, all the
> shared memory that is allocated to file locking is filled, and the
> server starts sending garbage back to the clients when they request
> locks, confusing the clients and creating all sorts of strange behavior.

If that were the case you would see "alloc failed" messages for
shared memory in the smbd logs and you could fix it by increasing
the shared memory area. Do you see this ?

> There are so many great features in Samba 2.0.x, I'd really like to
> start using it in production.  I hope the Samba team can come up with a
> solution to this problem eventually, but to this point I get the feeling
> they don't even recognize this as a problem.

No, I recognise it as a problem and both Andrew and I and
many others have studied this code for several years now,
we do have one bug that has been found and will be fixed
for 2.0.6, but the symptoms of this bug don't fit any of
the debug logs people have sent us regarding the problem.

The problem is that no one has ever come up with a *reproducible*
test case - the clients just seem to "randomly" fail.

Several people have also reported exactly this problem to
have been fixed once a network problem is corrected, so at
least some people (not all, I'll grant you) suffer this problem
due to network problems. 

I guess I'm saying I recognise the problem, and am willing
to believe people reporting it, however I don't yet have the
reproducible test case that will allow a bug in the Samba 
code to be found. 

There is a also the possibility it is a problem in the underlying
TCP timing between Solaris etc. and Windows clients that causes
clients to not respond to the oplock break message, and that changes
in Samba 2.0.x cause this timing problem to happen more than
1.9.18 does. But currently I know of no relevent differences in the
1.9.18 and 2.0.x code in this area.

Regards,

	Jeremy Allison,
	Samba Team.

-- 
--------------------------------------------------------
Buying an operating system without source is like buying
a self-assembly Space Shuttle with no instructions.
--------------------------------------------------------