leases and F_NOTIFY in samba 3 & 4

[Abhijith Das]

Hi List,

I understand that Samba uses F_SETLEASE, F_GETLEASE fcntls to implement 
oplocks in linux. Atleast in Samba3.
Does Samba4 also use linux kernel leases? How much of a performance 
impact is it to run Samba with oplocks disabled?
I'm about to implement lease support for GFS, but at the outset, there 
seems to be a significant performance impact for the fs.

Also, can somebody comment on how the F_NOTIFY fcntl is used in Samba?
James, can you comment on leases/F_NOTIFY from a CxFS perspective?

Many thanks,
--Abhi