6539707: (fc) MappedByteBuffer.force() method throws an IOException in a very simple test

Reviewed-by: alanb

src/java.base/share/classes/java/nio/MappedByteBuffer.java

@@ -26,6 +26,7 @@
 package java.nio;
 
 import java.io.FileDescriptor;
+import java.io.UncheckedIOException;
 import java.lang.ref.Reference;
 import java.util.Objects;
 
@@ -221,6 +222,10 @@ public abstract class MappedByteBuffer
      * mapping modes. This method may or may not have an effect for
      * implementation-specific mapping modes. </p>
      *
+     * @throws UncheckedIOException
+     *         If an I/O error occurs writing the buffer's content to the
+     *         storage device containing the mapped file
+     *
      * @return  This buffer
      */
     public final MappedByteBuffer force() {
@@ -272,6 +277,10 @@ public abstract class MappedByteBuffer
      *         if the preconditions on the index and length do not
      *         hold.
      *
+     * @throws UncheckedIOException
+     *         If an I/O error occurs writing the buffer's content to the
+     *         storage device containing the mapped file
+     *
      * @return  This buffer
      *
      * @since 13

src/java.base/share/classes/java/nio/MappedMemoryUtils.java

@@ -28,6 +28,8 @@ package java.nio;
 import jdk.internal.misc.Unsafe;
 
 import java.io.FileDescriptor;
+import java.io.IOException;
+import java.io.UncheckedIOException;
 
 /* package */ class MappedMemoryUtils {
 
@@ -94,7 +96,11 @@ import java.io.FileDescriptor;
         } else {
             // force writeback via file descriptor
             long offset = mappingOffset(address, index);
-            force0(fd, mappingAddress(address, offset, index), mappingLength(offset, length));
+            try {
+                force0(fd, mappingAddress(address, offset, index), mappingLength(offset, length));
+            } catch (IOException cause) {
+                throw new UncheckedIOException(cause);
+            }
         }
     }
 
@@ -103,7 +109,7 @@ import java.io.FileDescriptor;
     private static native boolean isLoaded0(long address, long length, int pageCount);
     private static native void load0(long address, long length);
     private static native void unload0(long address, long length);
-    private static native void force0(FileDescriptor fd, long address, long length);
+    private static native void force0(FileDescriptor fd, long address, long length) throws IOException;
 
     // utility methods