add disable volume_growth flag (#7196)

weed/server/master_grpc_server_assign.go

@@ -89,7 +89,7 @@ func (ms *MasterServer) Assign(ctx context.Context, req *master_pb.AssignRequest
 
 	for time.Now().Sub(startTime) < maxTimeout {
 		fid, count, dnList, shouldGrow, err := ms.Topo.PickForWrite(req.Count, option, vl)
-		if shouldGrow && !vl.HasGrowRequest() {
+		if shouldGrow && !vl.HasGrowRequest() && !ms.option.VolumeGrowthDisabled {
 			if err != nil && ms.Topo.AvailableSpaceFor(option) <= 0 {
 				err = fmt.Errorf("%s and no free volumes left for %s", err.Error(), option.String())
 			}