HDFS-14331. RBF: IOE While Removing Mount Entry. Contributed by Ayush Saxena.

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

@@ -303,8 +303,15 @@ public class RouterAdminServer extends AbstractService
   public RemoveMountTableEntryResponse removeMountTableEntry(
       RemoveMountTableEntryRequest request) throws IOException {
     // clear sub-cluster's quota definition
-    synchronizeQuota(request.getSrcPath(), HdfsConstants.QUOTA_RESET,
-        HdfsConstants.QUOTA_RESET);
+    try {
+      synchronizeQuota(request.getSrcPath(), HdfsConstants.QUOTA_RESET,
+          HdfsConstants.QUOTA_RESET);
+    } catch (Exception e) {
+      // Ignore exception, if any while reseting quota. Specifically to handle
+      // if the actual destination doesn't exist.
+      LOG.warn("Unable to clear quota at the destinations for {}: {}",
+          request.getSrcPath(), e.getMessage());
+    }
     return getMountTableStore().removeMountTableEntry(request);
   }
 

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

@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs.server.federation.router;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import java.io.IOException;
@@ -754,6 +755,12 @@ public class TestRouterQuota {
     assertNull(routerQuota);
     assertEquals(HdfsConstants.QUOTA_RESET, subClusterQuota.getQuota());
     assertEquals(HdfsConstants.QUOTA_RESET, subClusterQuota.getSpaceQuota());
+
+    // Verify removing mount entry with actual destinations not present.
+    mountTable = MountTable.newInstance("/mount",
+        Collections.singletonMap("ns0", "/testdir16"));
+    addMountTable(mountTable);
+    assertTrue(removeMountTable("/mount"));
   }
 
   @Test