HADOOP-13201. Print the directory paths when ViewFs denies the rename operation on internal dirs. Contributed by Tianyin Xiu

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ViewFs.java

@@ -472,14 +472,16 @@ public void renameInternal(final Path src, final Path dst,
   
     if (resSrc.isInternalDir()) {
       throw new AccessControlException(
-          "Cannot Rename within internal dirs of mount table: it is readOnly");
+          "Cannot Rename within internal dirs of mount table: src=" + src
+              + " is readOnly");
     }
 
     InodeTree.ResolveResult<AbstractFileSystem> resDst = 
                                 fsState.resolve(getUriPath(dst), false);
     if (resDst.isInternalDir()) {
       throw new AccessControlException(
-          "Cannot Rename within internal dirs of mount table: it is readOnly");
+          "Cannot Rename within internal dirs of mount table: dest=" + dst
+              + " is readOnly");
     }
     
     /**