NFS: add COPY_NOTIFY operation

Try using the delegation stateid, then the open stateid.

Only NL4_NETATTR, No support for NL4_NAME and NL4_URL.
Allow only one source server address to be returned for now.

To distinguish between same server copy offload ("intra") and
a copy between different server ("inter"), do a check of server
owner identity and also make sure server is capable of doing
a copy offload.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>

fs/nfs/nfs4client.c

@@ -629,7 +629,7 @@ out:
 /*
  * Returns true if the server major ids match
  */
-static bool
+bool
 nfs4_check_serverowner_major_id(struct nfs41_server_owner *o1,
 				struct nfs41_server_owner *o2)
 {