samba within nfs, locking mechanism fails

[Vincenzo De Sanctis]

this is the case:

serverA [ CentOs 5.6 kernel 2.6.18-238.12.1.el5.centos.plus, Samba ver. 3.5.21 ]
serverB [ CentOS 5.6 kernel 2.6.18-348.1.1.el5.centos.plus, Samba ver.
3.6.6-0.129.el5 ]
clientA [ WindowsXP ]
clientB [ WindowsXP ]


The serverA shares via Samba the resource [test]


[global]

   workgroup = DMIT
   netbios name = SAMBA
   server string = DMIT domain server
   interfaces = eth0
   smb ports = 445
   encrypt passwords = yes
    smb passwd file = /etc/samba/smbpasswd
   passdb backend = smbpasswd
   username map = /etc/samba/smbusers
   log file = /var/log/samba/pc/%m.log
   time server = Yes
   logon script = logon.bat
   logon path =
   logon drive = M:
   logon home = \\%L\%U
   domain logons = yes
   os level = 33
   preferred master = yes
   domain master = yes
   local master = yes
   printjob username = %M\%U
   hide dot files = No[netlogon]
   path = /etc/samba/netlogon
;   max protocol = smb2


[test]
   comment = test
   path = /test
   read only = no
   writable = yes
   create mode = 0775
   force create mode = 0775
   directory mode = 02775
   force directory mode = 02775
   public = no
   oplocks = no


il serverB monta tramite client nfs la risorsa /test  (mount
serverA:/test /test)
Queta e' il semplicissimo file di configurazione smb.conf di serverB:

[global]

   workgroup = DMIT
   domain master = no
   domain logons = no
   encrypt passwords = yes
   security = server
   password server = serverA
   interfaces = eth0
   smb ports = 445

[test]
   comment = test
   path = /test
   read only = no
   writable = yes
   create mode = 0775
   force create mode = 0775
   directory mode = 02775
   force directory mode = 02775
   public = no
   oplocks = no



Now on the clientA I open an excel2003 file from \\serverA\test and on
clientB i open the same file but from \\serverB\test (consider that
test is the same directory mounter from serverA via nfs)


This is what happens:

1) I can open without problem the file on clientA from \\serverA\test,
instead I have problem to open the the same file from \\serverB\test
(after 5min later it goes in timeout)


2) If I add "posix locking = no" on serverA and on serverB both
excel2003 files open without the locking mechanism.

3) I tried various combinations changing kernel oplocks, oplocks,
level2 oplocks, posix locking, locking, strict locking, nt acl support
but nothing changed.


4) I tried to open the same file from the same serverA (from clientA
and from clientB) without nfs and now the locking works well (both
from \\serverA\test)


The strange thing is that on my company newtwork there are many old
samba servers (samba 2.3) and they works well within nfs.
The proper way to use samba like a cluser is DFS insead of NFS, but
now I can not consider a migration or an upgrade to all the newtork,
so the best way at the moment is to use nfs, like the prevoiis
sysadmin did.


Have you had experience about this strange case?
Are there known bugs regarding the new samba versions + nfs ?

-- 
Vincenzo De Sanctis