"strict locking

This option checks every file access for a byte-range lock on the range
of bytes being accessed. This is typically not needed if a client
adheres to all the locking mechanisms in place. This option is set to no
by default; however, you can reset it per share as follows:

strict locking = yes

If this option is set to yes, mandatory locks are enforced on any file
with byte-range locks."

Extract from Chapter 8 of "Using Samba" 2nd edtion (The latest stable
distribution as of this writing is Samba 2.2.6, and this book focuses
mainly on the functionality supported in Samba 2.2.6)

Wouldn't be sufficient with locking=yes and veto oplock files ?

Soory if already have received this. I got a message back saying that it
could not be delivered and I think it was this