NFS locking problems with 7.0-RELEASE

[Rick Macklem]

On Tue, 30 Dec 2008, Bryan Alves wrote:

>> - Download my server patches (ftp.cis.uoguelph.ca/pub/nfsv4/FreeBSD7) and
>>  switch to using nfsv4, which has integral locking in the protocol.
>>
>> Have a good holiday, rick
>>
>>
> Is there another location where I can get the nfs4 patches?  That FTP seems
> to be down.
>
Seems to be working here. Just "ftp ftp.cis.uoguelph.ca", login 
"anonymous", then "cd pub/nfsv4/FreeBSD7". (Is it that you can't find
the machine? It's IP# is 131.104.48.112.)

> Also, outside the scope of this list, but since the discussion is opened, I
> might as well ask:
>
> If this NFS is the only remote mount that involves writing (it's opened
> read-only in other locations), and it's read/write locally, is it safe to
> use local locking?
>
Yes, I believe so. Even if there are multiple clients rw mounting a file
system, local locking should be fine unless there are multiple clients
writing the same file in the file system. (With a single writer and
multiple readers, an application might run into coherency problems if
that application was written to use byte range locking to maintain
coherency (ie. most recently written data visible to the readers), but
that seems unlikely to matter for most applications/environments. (And
I'm not sure if the NLM is wired into NFS is such a way as to maintain
full coherency for the locked byte ranges anyhow, since normally NFS
does not maintain full coherency?)

Have a happy new years, rick