HDFS-10876. Dispatcher#dispatch should log IOException stacktrace. Contributed by Manoj Govindassamy.

(cherry picked from commit 74b3dd514c86b46197e2e19d9824a423715cab30)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Dispatcher.java

@@ -350,7 +350,7 @@ public class Dispatcher {
         target.getDDatanode().setHasSuccess();
         LOG.info("Successfully moved " + this);
       } catch (IOException e) {
-        LOG.warn("Failed to move " + this + ": " + e.getMessage());
+        LOG.warn("Failed to move " + this, e);
         target.getDDatanode().setHasFailure();
         // Proxy or target may have some issues, delay before using these nodes
         // further in order to avoid a potential storm of "threads quota