HDFS-16501. Print the exception when reporting a bad block (#4062)

Reviewed-by: tomscut <litao@bigo.sg>
(cherry picked from commit 45ce1cce50c3ff65676d946e96bbc7846ad3131a)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java

@@ -293,7 +293,7 @@ public class VolumeScanner extends Thread {
             volume, block);
         return;
       }
-      LOG.warn("Reporting bad {} on {}", block, volume);
+      LOG.warn("Reporting bad {} on {}", block, volume, e);
       scanner.datanode.handleBadBlock(block, e, true);
     }
   }