--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/sun/nio/ch/FileLockImpl.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2001, 2009, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package sun.nio.ch;
+
+import java.io.IOException;
+import java.nio.channels.*;
+
+public class FileLockImpl
+    extends FileLock
+{
+    private volatile boolean invalid;
+
+    FileLockImpl(FileChannel channel, long position, long size, boolean shared)
+    {
+        super(channel, position, size, shared);
+    }
+
+    FileLockImpl(AsynchronousFileChannel channel, long position, long size, boolean shared)
+    {
+        super(channel, position, size, shared);
+    }
+
+    public boolean isValid() {
+        return !invalid;
+    }
+
+    void invalidate() {
+        assert Thread.holdsLock(this);
+        invalid = true;
+    }
+
+    public synchronized void release() throws IOException {
+        Channel ch = acquiredBy();
+        if (!ch.isOpen())
+            throw new ClosedChannelException();
+        if (isValid()) {
+            if (ch instanceof FileChannelImpl)
+                ((FileChannelImpl)ch).release(this);
+            else if (ch instanceof AsynchronousFileChannelImpl)
+                ((AsynchronousFileChannelImpl)ch).release(this);
+            else throw new AssertionError();
+            invalidate();
+        }
+    }
+}