VOP_LEASE

[Sam Leffler]

Doug Rabson wrote:
>
> On 12 Apr 2008, at 18:03, Kirk McKusick wrote:
>
>>> Date: Sat, 12 Apr 2008 02:13:15 -1000 (HST)
>>> From: Jeff Roberson <jroberson at jroberson.net>
>>> To: arch at freebsd.org
>>> Subject: VOP_LEASE
>>>
>>> As far as I can tell this has never been used.  Unless someone can 
>>> show me
>>> otherwise I'm going to go ahead and remove it.
>>>
>>> Thanks,
>>> Jeff
>>
>> VOP_LEASE is used by NQNFS and NFSv4. It notifies them when a file
>> is modified locally so that they know to update any outstanding
>> leases (e.g., evict any write lease for the file and do callbacks
>> for any read leases for the file). Deleting VOP_LEASE would break
>> NFS big time.
>
> I think our NQNFS support might have been removed some time ago - I 
> can't see any calls to VOP_LEASE in the code right now. Something like 
> VOP_LEASE would certainly be useful for a hypothetical future NFSv4 
> server. I believe that samba could use it too for its oplocks feature 
> which appears to be similar to NQNFS's leases and NFSv4's delegations.
>

Note NQNFS is long dead (netbsd removed it also not too long 
ago--together with VOP_LEASE).  Jeff doesn't say why he wants to remove 
it but it might be best removed only to return when there's a real 
consumer of the api.

    Sam