HDFS-11069. Tighten the authorization of datanode RPC. Contributed by Kihwal Lee

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

@@ -989,7 +989,7 @@ public class DataNode extends ReconfigurableBase
 
     // Is this by the DN user itself?
     assert dnUserName != null;
-    if (callerUgi.getShortUserName().equals(dnUserName)) {
+    if (callerUgi.getUserName().equals(dnUserName)) {
       return;
     }
 
@@ -1348,7 +1348,7 @@ public class DataNode extends ReconfigurableBase
     this.blockPoolTokenSecretManager = new BlockPoolTokenSecretManager();
 
     // Login is done by now. Set the DN user name.
-    dnUserName = UserGroupInformation.getCurrentUser().getShortUserName();
+    dnUserName = UserGroupInformation.getCurrentUser().getUserName();
     LOG.info("dnUserName = " + dnUserName);
     LOG.info("supergroup = " + supergroup);
     initIpcServer();