HDFS-14010. Pass correct DF usage to ReservedSpaceCalculator builder.…

… Contributed by Virajith Jalaparti.

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

@@ -163,6 +163,13 @@ public class FsVolumeImpl implements FsVolumeSpi {
     this.storageType = storageLocation.getStorageType();
     this.configuredCapacity = -1;
     this.usage = usage;
+    if (this.usage != null) {
+      reserved = new ReservedSpaceCalculator.Builder(conf)
+          .setUsage(this.usage).setStorageType(storageType).build();
+    } else {
+      reserved = null;
+      LOG.warn("Setting reserved to null as usage is null");
+    }
     if (currentDir != null) {
       File parent = currentDir.getParentFile();
       cacheExecutor = initializeCacheExecutor(parent);
@@ -173,8 +180,6 @@ public class FsVolumeImpl implements FsVolumeSpi {
     }
     this.conf = conf;
     this.fileIoProvider = fileIoProvider;
-    this.reserved = new ReservedSpaceCalculator.Builder(conf)
-        .setUsage(usage).setStorageType(storageType).build();
   }
 
   protected ThreadPoolExecutor initializeCacheExecutor(File parent) {
@@ -473,7 +478,7 @@ long getRecentReserved() {
   }
 
   long getReserved(){
-    return reserved.getReserved();
+    return reserved != null ? reserved.getReserved() : 0;
   }
 
   @VisibleForTesting

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/TestProvidedImpl.java

@@ -353,6 +353,14 @@ public void setUp() throws IOException {
     }
   }
 
+  @Test
+  public void testReserved() throws Exception {
+    for (FsVolumeSpi vol : providedVolumes) {
+      // the reserved space for provided volumes should be 0.
+      assertEquals(0, ((FsVolumeImpl) vol).getReserved());
+    }
+  }
+
   @Test
   public void testProvidedVolumeImpl() throws IOException {