HDFS-11891. DU#refresh should print the path of the directory when an exception is caught. Contributed by Chen Liang.

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

@@ -52,7 +52,8 @@ public class DU extends CachingGetSpaceUsed {
     try {
       duShell.startRefresh();
     } catch (IOException ioe) {
-      LOG.warn("Could not get disk usage information", ioe);
+      LOG.warn("Could not get disk usage information for path {}",
+          getDirPath(), ioe);
     }
   }