NFS: Set EXCHGID4_FLAG_SUPP_MOVED_MIGR

Broadly speaking, v4.1 migration is untested.  There are no servers
in the wild that support NFSv4.1 migration.  However, as server
implementations become available, we do want to enable testing by
developers, while leaving it disabled for environments for which
broken migration support would be an unpleasant surprise.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8aa8ff3..1463c71 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6596,8 +6596,14 @@
 	struct nfs41_exchange_id_args args = {
 		.verifier = &verifier,
 		.client = clp,
+#ifdef CONFIG_NFS_V4_1_MIGRATION
 		.flags = EXCHGID4_FLAG_SUPP_MOVED_REFER |
-			EXCHGID4_FLAG_BIND_PRINC_STATEID,
+			 EXCHGID4_FLAG_BIND_PRINC_STATEID |
+			 EXCHGID4_FLAG_SUPP_MOVED_MIGR,
+#else
+		.flags = EXCHGID4_FLAG_SUPP_MOVED_REFER |
+			 EXCHGID4_FLAG_BIND_PRINC_STATEID,
+#endif
 	};
 	struct nfs41_exchange_id_res res = {
 		0