From fdd96e46d1f89f0ecdb9b1836dc7fca9fbb954fd Mon Sep 17 00:00:00 2001
From: Shashikant Banerjee <shashikant@apache.org>
Date: Wed, 18 Dec 2019 22:50:46 +0530
Subject: [PATCH] HDFS-15012. NN fails to parse Edit logs after applying
 HDFS-13101. Contributed by Shashikant Banerjee.

---
 .../DirectoryWithSnapshotFeature.java         |  8 ++-
 .../snapshot/TestRenameWithSnapshots.java     | 64 +++++++++++++++++++
 2 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/DirectoryWithSnapshotFeature.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/DirectoryWithSnapshotFeature.java
index 7fb639c6a46..4e756c7268c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/DirectoryWithSnapshotFeature.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/DirectoryWithSnapshotFeature.java
@@ -739,8 +739,12 @@ public class DirectoryWithSnapshotFeature implements INode.Feature {
           // were created before "prior" will be covered by the later 
           // cleanSubtreeRecursively call.
           if (priorCreated != null) {
-            if (currentINode.isLastReference()) {
-              // if this is the last reference, the created list can be
+            if (currentINode.isLastReference() &&
+                    currentINode.getDiffs().getLastSnapshotId() == prior) {
+              // If this is the last reference of the directory inode and it
+              // can not be accessed in any of the subsequent snapshots i.e,
+              // this is the latest snapshot diff and if this is the last
+              // reference, the created list can be
               // destroyed.
               priorDiff.getChildrenDiff().destroyCreatedList(
                   reclaimContext, currentINode);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java
index f5b5345bf86..128e3ba8bec 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java
@@ -49,6 +49,7 @@ import org.mockito.Mockito;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.PrintWriter;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.Random;
@@ -2412,4 +2413,67 @@ public class TestRenameWithSnapshots {
     assertTrue(existsInDiffReport(entries, DiffType.RENAME, "foo/file2", "newDir/file2"));
     assertTrue(existsInDiffReport(entries, DiffType.RENAME, "foo/file3", "newDir/file1"));
   }
+
+  @Test (timeout=60000)
+  public void testDoubleRenamesWithSnapshotDelete() throws Exception {
+    hdfs.mkdirs(sub1);
+    hdfs.allowSnapshot(sub1);
+    final Path dir1 = new Path(sub1, "dir1");
+    final Path dir2 = new Path(sub1, "dir2");
+    final Path dir3 = new Path(sub1, "dir3");
+    final String snap3 = "snap3";
+    final String snap4 = "snap4";
+    final String snap5 = "snap5";
+    final String snap6 = "snap6";
+    final Path foo = new Path(dir2, "foo");
+    final Path bar = new Path(dir2, "bar");
+    hdfs.createSnapshot(sub1, snap1);
+    hdfs.mkdirs(dir1, new FsPermission((short) 0777));
+    rename(dir1, dir2);
+    hdfs.createSnapshot(sub1, snap2);
+    DFSTestUtil.createFile(hdfs, foo, BLOCKSIZE, REPL, SEED);
+    DFSTestUtil.createFile(hdfs, bar, BLOCKSIZE, REPL, SEED);
+    hdfs.createSnapshot(sub1, snap3);
+    hdfs.delete(foo, false);
+    DFSTestUtil.createFile(hdfs, foo, BLOCKSIZE, REPL, SEED);
+    hdfs.createSnapshot(sub1, snap4);
+    hdfs.delete(foo, false);
+    DFSTestUtil.createFile(hdfs, foo, BLOCKSIZE, REPL, SEED);
+    hdfs.createSnapshot(sub1, snap5);
+    rename(dir2, dir3);
+    hdfs.createSnapshot(sub1, snap6);
+    hdfs.delete(dir3, true);
+    deleteSnapshot(sub1, snap6);
+    deleteSnapshot(sub1, snap3);
+    // save namespace and restart Namenode
+    hdfs.setSafeMode(SafeModeAction.SAFEMODE_ENTER);
+    hdfs.saveNamespace();
+    hdfs.setSafeMode(SafeModeAction.SAFEMODE_LEAVE);
+    cluster.restartNameNode(true);
+  }
+
+
+  void rename(Path src, Path dst) throws Exception {
+    printTree("Before rename " + src + " -> " + dst);
+    hdfs.rename(src, dst);
+    printTree("After rename " + src + " -> " + dst);
+  }
+
+  void deleteSnapshot(Path directory, String snapshotName) throws Exception {
+    hdfs.deleteSnapshot(directory, snapshotName);
+    printTree("deleted snapshot " + snapshotName);
+  }
+
+  private final PrintWriter output = new PrintWriter(System.out, true);
+  private int printTreeCount = 0;
+
+  String printTree(String label) throws Exception {
+    output.println();
+    output.println();
+    output.println("***** " + printTreeCount++ + ": " + label);
+    final String b =
+        fsn.getFSDirectory().getINode("/").dumpTreeRecursively().toString();
+    output.println(b);
+    return b;
+  }
 }