HDFS-7885. Datanode should not trust the generation stamp provided by client. Contributed by Tsz Wo Nicholas Sze.

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

@@ -1104,6 +1104,9 @@ Release 2.7.0 - UNRELEASED
 
     HDFS-7434. DatanodeID hashCode should not be mutable. (daryn via kihwal)
 
+    HDFS-7885. Datanode should not trust the generation stamp provided by
+    client. (Tsz Wo Nicholas Sze via jing9)
+
     BREAKDOWN OF HDFS-7584 SUBTASKS AND RELATED JIRAS
 
       HDFS-7720. Quota by Storage Type API, tools and ClientNameNode

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -2568,6 +2568,21 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   @Override // FsDatasetSpi
   public BlockLocalPathInfo getBlockLocalPathInfo(ExtendedBlock block)
       throws IOException {
+    synchronized(this) {
+      final Replica replica = volumeMap.get(block.getBlockPoolId(),
+          block.getBlockId());
+      if (replica == null) {
+        throw new ReplicaNotFoundException(block);
+      }
+      if (replica.getGenerationStamp() < block.getGenerationStamp()) {
+        throw new IOException(
+            "Replica generation stamp < block generation stamp, block="
+            + block + ", replica=" + replica);
+      } else if (replica.getGenerationStamp() > block.getGenerationStamp()) {
+        block.setGenerationStamp(replica.getGenerationStamp());
+      }
+    }
+
     File datafile = getBlockFile(block);
     File metafile = FsDatasetUtil.getMetaFile(datafile, block.getGenerationStamp());
     BlockLocalPathInfo info = new BlockLocalPathInfo(block,

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestBlockReaderLocalLegacy.java

@@ -30,11 +30,16 @@ import org.apache.hadoop.fs.FSDataInputStream;
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
+import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.net.unix.DomainSocket;
 import org.apache.hadoop.net.unix.TemporarySocketDirectory;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.token.Token;
 import org.junit.Assert;
 import org.junit.Assume;
 import org.junit.BeforeClass;
@@ -153,4 +158,62 @@ public class TestBlockReaderLocalLegacy {
     Arrays.equals(orig, buf);
     cluster.shutdown();
   }
+
+  @Test(timeout=20000)
+  public void testBlockReaderLocalLegacyWithAppend() throws Exception {
+    final short REPL_FACTOR = 1;
+    final HdfsConfiguration conf = getConfiguration(null);
+    conf.setBoolean(DFSConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL, true);
+
+    final MiniDFSCluster cluster =
+        new MiniDFSCluster.Builder(conf).numDataNodes(1).build();
+    cluster.waitActive();
+
+    final DistributedFileSystem dfs = cluster.getFileSystem();
+    final Path path = new Path("/testBlockReaderLocalLegacy");
+    DFSTestUtil.createFile(dfs, path, 10, REPL_FACTOR, 0);
+    DFSTestUtil.waitReplication(dfs, path, REPL_FACTOR);
+
+    final ClientDatanodeProtocol proxy;
+    final Token<BlockTokenIdentifier> token;
+    final ExtendedBlock originalBlock;
+    final long originalGS;
+    {
+      final LocatedBlock lb = cluster.getNameNode().getRpcServer()
+          .getBlockLocations(path.toString(), 0, 1).get(0);
+      proxy = DFSUtil.createClientDatanodeProtocolProxy(
+          lb.getLocations()[0], conf, 60000, false);
+      token = lb.getBlockToken();
+
+      // get block and generation stamp
+      final ExtendedBlock blk = new ExtendedBlock(lb.getBlock());
+      originalBlock = new ExtendedBlock(blk);
+      originalGS = originalBlock.getGenerationStamp();
+
+      // test getBlockLocalPathInfo
+      final BlockLocalPathInfo info = proxy.getBlockLocalPathInfo(blk, token);
+      Assert.assertEquals(originalGS, info.getBlock().getGenerationStamp());
+    }
+
+    { // append one byte
+      FSDataOutputStream out = dfs.append(path);
+      out.write(1);
+      out.close();
+    }
+
+    {
+      // get new generation stamp
+      final LocatedBlock lb = cluster.getNameNode().getRpcServer()
+          .getBlockLocations(path.toString(), 0, 1).get(0);
+      final long newGS = lb.getBlock().getGenerationStamp();
+      Assert.assertTrue(newGS > originalGS);
+
+      // getBlockLocalPathInfo using the original block.
+      Assert.assertEquals(originalGS, originalBlock.getGenerationStamp());
+      final BlockLocalPathInfo info = proxy.getBlockLocalPathInfo(
+          originalBlock, token);
+      Assert.assertEquals(newGS, info.getBlock().getGenerationStamp());
+    }
+    cluster.shutdown();
+  }
 }