8293456: runtime/os/TestTracePageSizes.java sub-tests fail with "AssertionError: No memory range found for address: NNNN"

Reviewed-by: alanb, lancea

src/java.base/unix/classes/sun/nio/fs/UnixFileSystem.java

@@ -668,8 +668,11 @@ abstract class UnixFileSystem
             // set to true when file and attributes copied
             boolean complete = false;
             try {
+                // set to true when data copied
                 boolean copied = false;
-                if (!directCopyNotSupported) {
+
+                // Some forms of direct copy do not work on zero size files
+                if (!directCopyNotSupported && attrs.size() > 0) {
                     // copy bytes to target using platform function
                     long comp = Blocker.begin();
                     try {