HDFS-9625. set replication for empty file failed when set storage policy (Contributed by DENG FEI)

(cherry picked from commit b7372b7166a13111b98794602ca4c166dfd78d29)
(cherry picked from commit 845acfd96c8461ebb412cd1daec51e89ce9f1c18)

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

@@ -1718,6 +1718,9 @@ Release 2.7.3 - UNRELEASED
     HDFS-9661. Deadlock in DN.FsDatasetImpl between moveBlockAcrossStorage and
     createRbw (ade via vinayakumarb)
 
+    HDFS-9625. set replication for empty file failed when set storage policy
+    (DENG FEI via vinayakumarb)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -811,6 +811,10 @@ public class FSDirectory implements Closeable {
       long dsDelta, short oldRep, short newRep) {
     EnumCounters<StorageType> typeSpaceDeltas =
         new EnumCounters<StorageType>(StorageType.class);
+    // empty file
+    if(dsDelta == 0){
+      return typeSpaceDeltas;
+    }
     // Storage type and its quota are only available when storage policy is set
     if (storagePolicyID != HdfsConstants.BLOCK_STORAGE_POLICY_ID_UNSPECIFIED) {
       BlockStoragePolicy storagePolicy = getBlockManager().getStoragePolicy(storagePolicyID);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSetrepIncreasing.java

@@ -83,4 +83,23 @@ public class TestSetrepIncreasing {
   public void testSetrepIncreasingSimulatedStorage() throws IOException {
     setrep(3, 7, true);
   }
+
+  @Test
+  public void testSetRepWithStoragePolicyOnEmptyFile() throws Exception {
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster =
+        new MiniDFSCluster.Builder(conf).numDataNodes(1).build();
+    DistributedFileSystem dfs = cluster.getFileSystem();
+    try {
+      Path d = new Path("/tmp");
+      dfs.mkdirs(d);
+      dfs.setStoragePolicy(d, "HOT");
+      Path f = new Path(d, "foo");
+      dfs.createNewFile(f);
+      dfs.setReplication(f, (short) 4);
+    } finally {
+      dfs.close();
+      cluster.shutdown();
+    }
+ }
 }