HDFS-16954. RBF: The operation of renaming a multi-subcluster directory to a single-cluster directory should throw ioexception. (#5483). Contributed by Max Xie.

Reviewed-by: Inigo Goiri <inigoiri@apache.org>
Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterClientProtocol.java

@@ -614,6 +614,11 @@ public class RouterClientProtocol implements ClientProtocol {
         new Class<?>[] {String.class, String.class},
         new RemoteParam(), dstParam);
     if (isMultiDestDirectory(src)) {
+      if (locs.size() != srcLocations.size()) {
+        throw new IOException("Rename of " + src + " to " + dst + " is not"
+            + " allowed. The number of remote locations for both source and"
+            + " target should be same.");
+      }
       return rpcClient.invokeAll(locs, method);
     } else {
       return rpcClient.invokeSequential(locs, method, Boolean.class,
@@ -641,6 +646,11 @@ public class RouterClientProtocol implements ClientProtocol {
         new Class<?>[] {String.class, String.class, options.getClass()},
         new RemoteParam(), dstParam, options);
     if (isMultiDestDirectory(src)) {
+      if (locs.size() != srcLocations.size()) {
+        throw new IOException("Rename of " + src + " to " + dst + " is not"
+            + " allowed. The number of remote locations for both source and"
+            + " target should be same.");
+      }
       rpcClient.invokeConcurrent(locs, method);
     } else {
       rpcClient.invokeSequential(locs, method, null, null);

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterRPCMultipleDestinationMountTableResolver.java

@@ -720,6 +720,47 @@ public class TestRouterRPCMultipleDestinationMountTableResolver {
     }
   }
 
+  /**
+   *  Test rename a dir from src dir (mapped to both ns0 and ns1) to ns0.
+   */
+  @Test
+  public void testRenameWithMultiDestinations() throws Exception {
+    //create a mount point with multiple destinations
+    String srcDir = "/mount-source-dir";
+    Path path = new Path(srcDir);
+    Map<String, String> destMap = new HashMap<>();
+    destMap.put("ns0", srcDir);
+    destMap.put("ns1", srcDir);
+    nnFs0.mkdirs(path);
+    nnFs1.mkdirs(path);
+    MountTable addEntry =
+        MountTable.newInstance(srcDir, destMap);
+    addEntry.setDestOrder(DestinationOrder.RANDOM);
+    assertTrue(addMountTable(addEntry));
+
+    //create a mount point with a single destinations ns0
+    String targetDir = "/ns0_test";
+    nnFs0.mkdirs(new Path(targetDir));
+    MountTable addDstEntry = MountTable.newInstance(targetDir,
+        Collections.singletonMap("ns0", targetDir));
+    assertTrue(addMountTable(addDstEntry));
+
+    //mkdir sub dirs in srcDir  mapping ns0 & ns1
+    routerFs.mkdirs(new Path(srcDir + "/dir1"));
+    routerFs.mkdirs(new Path(srcDir + "/dir1/dir_1"));
+    routerFs.mkdirs(new Path(srcDir + "/dir1/dir_2"));
+    routerFs.mkdirs(new Path(targetDir));
+
+    //try to rename sub dir in srcDir (mapping to ns0 & ns1) to targetDir
+    // (mapping ns0)
+    LambdaTestUtils.intercept(IOException.class, "The number of" +
+            " remote locations for both source and target should be same.",
+        () -> {
+          routerFs.rename(new Path(srcDir + "/dir1/dir_1"),
+              new Path(targetDir));
+        });
+  }
+
   /**
    * Test to verify rename operation on directories in case of multiple
    * destinations.