HDFS-4159. Rename should fail when the destination directory is snapshottable and has snapshots. Contributed by Jing Zhao

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2802@1406771 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-2802.txt

@@ -59,3 +59,6 @@ Branch-2802 Snapshot (Unreleased)
 
   HDFS-4150.  Update the inode in the block map when a snapshotted file or a
   snapshot file is deleted. (Jing Zhao via szetszwo)
+
+  HDFS-4159. Rename should fail when the destination directory is snapshottable
+  and has snapshots. (Jing Zhao via szetszwo)

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

@@ -705,6 +705,16 @@ boolean unprotectedRenameTo(String src, String dst, long timestamp,
             + error);
         throw new IOException(error);
       }
+      INode snapshotNode = hasSnapshot(dstInode);
+      if (snapshotNode != null) {
+        error = "The direcotry " + dstInode.getFullPathName()
+            + " cannot be deleted for renaming since "
+            + snapshotNode.getFullPathName()
+            + " is snapshottable and already has snapshots";
+        NameNode.stateChangeLog.warn("DIR* FSDirectory.unprotectedRenameTo: "
+            + error);
+        throw new IOException(error);
+      }
     }
     if (dstInodes[dstInodes.length - 2] == null) {
       error = "rename destination parent " + dst + " not found.";
@@ -1145,13 +1155,16 @@ private static INode hasSnapshot(INode target) {
           && ((INodeDirectorySnapshottable) targetDir).getNumSnapshots() > 0) {
         return target;
       }
-      for (INode child : targetDir.getChildren()) {
+      List<INode> children = targetDir.getChildren();
+      if (children != null) {
+        for (INode child : children) {
           INode snapshotDir = hasSnapshot(child);
           if (snapshotDir != null) {
             return snapshotDir;
           }
         }
       }
+    }
     return null;
   }
 

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

@@ -28,6 +28,7 @@
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Options.Rename;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DFSTestUtil;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
@@ -253,6 +254,64 @@ public void testDeleteDirectoryWithSnapshot2() throws Exception {
     hdfs.delete(dir, true);
   }  
   
+  /**
+   * Renaming a directory to another directory with snapshots must fail.
+   */
+  @Test
+  public void testRenameToDirectoryWithSnapshot() throws Exception {
+    // create the directory sub1
+    hdfs.mkdirs(sub1);
+    
+    Path sub2 = new Path(dir, "sub2");
+    Path file2 = new Path(sub2, "file");
+    DFSTestUtil.createFile(hdfs, file2, BLOCKSIZE, REPLICATION, seed);
+    
+    // The normal rename should succeed
+    hdfs.rename(sub2, sub1, Rename.OVERWRITE);
+    
+    // Create sub3 and create snapshot for it 
+    Path sub3 = new Path(dir, "sub3");
+    hdfs.mkdirs(sub3);
+    SnapshotTestHelper.createSnapshot(hdfs, sub3, "s1");
+    
+    exception.expect(RemoteException.class);
+    String error = "The direcotry " + sub3.toString()
+        + " cannot be deleted for renaming since " + sub3.toString()
+        + " is snapshottable and already has snapshots";
+    exception.expectMessage(error);
+    hdfs.rename(sub1, sub3, Rename.OVERWRITE);
+  }
+  
+  /**
+   * Renaming a directory to another directory with snapshots
+   * must fail.
+   */
+  @Test
+  public void testRenameToDirectoryWithSnapshot2() throws Exception {
+    Path file0 = new Path(sub1, "file0");
+    Path file1 = new Path(sub1, "file1");
+    DFSTestUtil.createFile(hdfs, file0, BLOCKSIZE, REPLICATION, seed);
+    DFSTestUtil.createFile(hdfs, file1, BLOCKSIZE, REPLICATION, seed);
+    
+    Path sub2 = new Path(dir, "sub2");
+    Path file2 = new Path(sub2, "file");
+    DFSTestUtil.createFile(hdfs, file2, BLOCKSIZE, REPLICATION, seed);
+    
+    // Create snapshot for sub1
+    SnapshotTestHelper.createSnapshot(hdfs, sub1, "s1");
+    // Then delete file0 and file1 so that the renaming can succeed if without
+    // snapshots
+    hdfs.delete(file0, true);
+    hdfs.delete(file1, true);
+    
+    exception.expect(RemoteException.class);
+    String error = "The direcotry " + sub1.toString()
+        + " cannot be deleted for renaming since " + sub1.toString()
+        + " is snapshottable and already has snapshots";
+    exception.expectMessage(error);
+    hdfs.rename(sub2, sub1, Rename.OVERWRITE);
+  }
+  
   /**
    * Base class to present changes applied to current file/dir. A modification
    * can be file creation, deletion, or other modifications such as appending on