HDFS-8596. TestDistributedFileSystem et al tests are broken in branch-2 due to incorrect setting of "datanode" attribute. Contributed by Yongjun Zhang.

(cherry picked from commit b0dc291961410b6ac2b275cdcff4b95d75727e8d)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/DatanodeHttpServer.java

(cherry picked from commit cd578fa289252b0ae1e27f7e7b097cceeb2c30ff)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -116,6 +116,9 @@ Release 2.7.1 - UNRELEASED
     HDFS-8572. DN always uses HTTP/localhost@REALM principals in SPNEGO.
     (wheat9)
 
+    HDFS-8596. TestDistributedFileSystem et al tests are broken in branch-2
+    due to incorrect setting of "datanode" attribute. (Yongjun Zhang)
+
 Release 2.7.0 - 2015-04-20
 
   INCOMPATIBLE CHANGES

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

@@ -756,7 +756,7 @@ public class DataNode extends ReconfigurableBase
     ServerSocketChannel httpServerChannel = secureResources != null ?
         secureResources.getHttpServerChannel() : null;
 
-    this.httpServer = new DatanodeHttpServer(conf, httpServerChannel);
+    this.httpServer = new DatanodeHttpServer(conf, this, httpServerChannel);
     httpServer.start();
     if (httpServer.getHttpAddress() != null) {
       infoPort = httpServer.getHttpAddress().getPort();

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

@@ -75,6 +75,7 @@ public class DatanodeHttpServer implements Closeable {
   static final Log LOG = LogFactory.getLog(DatanodeHttpServer.class);
 
   public DatanodeHttpServer(final Configuration conf,
+      final DataNode datanode,
       final ServerSocketChannel externalHttpChannel)
     throws IOException {
     this.conf = conf;
@@ -95,7 +96,7 @@ public class DatanodeHttpServer implements Closeable {
     this.infoServer.addInternalServlet(null, "/getFileChecksum/*",
         FileChecksumServlets.GetServlet.class);
 
-    this.infoServer.setAttribute("datanode", this);
+    this.infoServer.setAttribute("datanode", datanode);
     this.infoServer.setAttribute(JspHelper.CURRENT_CONF, conf);
     this.infoServer.addServlet(null, "/blockScannerReport",
                                BlockScanner.Servlet.class);