nfsd41: implement NFS4_SHARE_WANT_NO_DELEG, NFS4_OPEN_DELEGATE_NONE_EXT, why_no_deleg

Respect client request for not getting a delegation in NFSv4.1
Appropriately return delegation "type" NFS4_OPEN_DELEGATE_NONE_EXT
and WND4_NOT_WANTED reason.

[nfsd41: add missing break when encoding op_why_no_deleg]
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index a58f206..f8fcddc 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2849,6 +2849,20 @@
 		WRITE32(0);   /* XXX: is NULL principal ok? */
 		ADJUST_ARGS();
 		break;
+	case NFS4_OPEN_DELEGATE_NONE_EXT: /* 4.1 */
+		switch (open->op_why_no_deleg) {
+		case WND4_CONTENTION:
+		case WND4_RESOURCE:
+			RESERVE_SPACE(8);
+			WRITE32(open->op_why_no_deleg);
+			WRITE32(0);	/* deleg signaling not supported yet */
+			break;
+		default:
+			RESERVE_SPACE(4);
+			WRITE32(open->op_why_no_deleg);
+		}
+		ADJUST_ARGS();
+		break;
 	default:
 		BUG();
 	}