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/nfs4proc.c

@@ -9899,6 +9899,7 @@ static const struct nfs4_minor_version_ops nfs_v4_2_minor_ops = {
 		| NFS_CAP_ALLOCATE
 		| NFS_CAP_COPY
 		| NFS_CAP_OFFLOAD_CANCEL
+		| NFS_CAP_COPY_NOTIFY
 		| NFS_CAP_DEALLOCATE
 		| NFS_CAP_SEEK
 		| NFS_CAP_LAYOUTSTATS