--- /dev/null	2018-05-09 06:13:36.966491568 +0200
+++ new/src/hotspot/share/memory/metaspace/metablock.hpp	2018-05-09 12:24:40.419636383 +0200
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_MEMORY_METASPACE_METABLOCK_HPP_
+#define SHARE_MEMORY_METASPACE_METABLOCK_HPP_
+
+#include "memory/metaspace/metabase.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+namespace metaspace {
+namespace internals {
+
+// Metablock is the unit of allocation from a Chunk.
+//
+// A Metablock may be reused by its SpaceManager but are never moved between
+// SpaceManagers.  There is no explicit link to the Metachunk
+// from which it was allocated.  Metablock may be deallocated and
+// put on a freelist but the space is never freed, rather
+// the Metachunk it is a part of will be deallocated when it's
+// associated class loader is collected.
+
+class Metablock : public Metabase<Metablock> {
+  friend class VMStructs;
+ public:
+  Metablock(size_t word_size) : Metabase<Metablock>(word_size) {}
+};
+
+} // namespace metaspace
+} // namespace internals
+
+#endif /* SHARE_MEMORY_METASPACE_METABLOCK_HPP_ */