HDFS-2285. BackupNode should reject requests to modify namespace. Contributed by Konstantin Shvachko and Uma Maheswara Rao G.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1195013 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -1816,6 +1816,9 @@ Release 0.22.0 - Unreleased
     HDFS-2452. OutOfMemoryError in DataXceiverServer takes down the DataNode
     (Uma Maheswara Rao via cos)
 
+    HDFS-2285. BackupNode should reject requests to modify namespace.
+    (shv and Uma Maheswara Rao)
+
 Release 0.21.1 - Unreleased
 
     HDFS-1466. TestFcHdfsSymlink relies on /tmp/test not existing. (eli)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/BackupNode.java

@@ -28,6 +28,7 @@
 import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocolR23Compatible.JournalProtocolServerSideTranslatorR23;
 import org.apache.hadoop.hdfs.protocolR23Compatible.JournalWireProtocol;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
@@ -137,6 +138,10 @@ protected void initialize(Configuration conf) throws IOException {
                  CommonConfigurationKeys.FS_TRASH_INTERVAL_DEFAULT);
     NamespaceInfo nsInfo = handshake(conf);
     super.initialize(conf);
+    if (false == namesystem.isInSafeMode()) {
+      namesystem.setSafeMode(SafeModeAction.SAFEMODE_ENTER);
+    }
+
     // Backup node should never do lease recovery,
     // therefore lease hard limit should never expire.
     namesystem.leaseManager.setLeasePeriod(
@@ -191,6 +196,11 @@ public void stop() {
     super.stop();
   }
   
+  /* @Override */// NameNode
+  public boolean setSafeMode(SafeModeAction action) throws IOException {
+    throw new UnsupportedActionException("setSafeMode");
+  }
+  
   static class BackupNodeRpcServer extends NameNodeRpcServer implements
       JournalProtocol {
     private final String nnRpcAddress;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/Checkpointer.java

@@ -243,6 +243,10 @@ void doCheckpoint() throws IOException {
     }
     
     long txid = bnImage.getLastAppliedTxId();
+    
+    backupNode.namesystem.dir.setReady();
+    backupNode.namesystem.setBlockTotal();
+    
     bnImage.saveFSImageInAllDirs(backupNode.getNamesystem(), txid);
     bnStorage.writeAll();
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java

@@ -159,6 +159,11 @@ private BlockManager getBlockManager() {
    */
   void imageLoadComplete() {
     Preconditions.checkState(!ready, "FSDirectory already loaded");
+    setReady();
+  }
+
+  void setReady() {
+    if(ready) return;
     writeLock();
     try {
       setReady(true);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -3344,7 +3344,7 @@ public void decrementSafeBlockCount(Block b) {
   /**
    * Set the total number of blocks in the system. 
    */
-  private void setBlockTotal() {
+  void setBlockTotal() {
     // safeMode is volatile, and may be set to null at any time
     SafeModeInfo safeMode = this.safeMode;
     if (safeMode == null)

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBackupNode.java

@@ -19,9 +19,12 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.InetSocketAddress;
 import java.util.Collections;
 import java.util.List;
 
+import junit.framework.TestCase;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.commons.logging.impl.Log4JLogger;
@@ -29,13 +32,13 @@
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.namenode.FileJournalManager.EditLogFile;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
-import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.log4j.Level;
 
@@ -44,8 +47,6 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 
-import junit.framework.TestCase;
-
 public class TestBackupNode extends TestCase {
   public static final Log LOG = LogFactory.getLog(TestBackupNode.class);
 
@@ -241,8 +242,11 @@ public void testBackupNode() throws Exception {
   void testCheckpoint(StartupOption op) throws Exception {
     Path file1 = new Path("checkpoint.dat");
     Path file2 = new Path("checkpoint2.dat");
+    Path file3 = new Path("backup.dat");
 
     Configuration conf = new HdfsConfiguration();
+    short replication = (short)conf.getInt("dfs.replication", 3);
+    int numDatanodes = Math.max(3, replication);
     conf.set(DFSConfigKeys.DFS_BLOCKREPORT_INITIAL_DELAY_KEY, "0");
     conf.setInt(DFSConfigKeys.DFS_DATANODE_SCAN_PERIOD_HOURS_KEY, -1); // disable block scanner
     conf.setInt(DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_TXNS_KEY, 1);
@@ -290,7 +294,7 @@ void testCheckpoint(StartupOption op) throws Exception {
       //
       // Restart cluster and verify that file1 still exist.
       //
-      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(0)
+      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDatanodes)
                                                 .format(false).build();
       fileSys = cluster.getFileSystem();
       // check that file1 still exists
@@ -319,6 +323,26 @@ void testCheckpoint(StartupOption op) throws Exception {
       backup.doCheckpoint();
       waitCheckpointDone(cluster, backup, txid);
 
+      // Try BackupNode operations
+      InetSocketAddress add = backup.getNameNodeAddress();
+      // Write to BN
+      FileSystem bnFS = FileSystem.get(new Path("hdfs://"
+          + NameNode.getHostPortString(add)).toUri(), conf);
+      boolean canWrite = true;
+      try {
+        TestCheckpoint.writeFile(bnFS, file3, replication);
+      } catch (IOException eio) {
+        LOG.info("Write to BN failed as expected: ", eio);
+        canWrite = false;
+      }
+      assertFalse("Write to BackupNode must be prohibited.", canWrite);
+
+      TestCheckpoint.writeFile(fileSys, file3, replication);
+      TestCheckpoint.checkFile(fileSys, file3, replication);
+      // should also be on BN right away
+      assertTrue("file3 does not exist on BackupNode",
+          op != StartupOption.BACKUP || bnFS.exists(file3));
+
     } catch(IOException e) {
       LOG.error("Error in TestBackupNode:", e);
       assertTrue(e.getLocalizedMessage(), false);