HDFS-16177. Bug fix for Util#receiveFile (#3310)

Reviewed-by: Hui Fei <ferhui@apache.org>

Author: tomscut

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Util.java

@@ -287,7 +287,7 @@ public static MD5Hash receiveFile(String url, List<File> localPaths,
         fos.getChannel().force(true);
         fos.close();
         double writeSec = Math.max(((float)
-            (flushStartTime - Time.monotonicNow())) / 1000.0, 0.001);
+            (Time.monotonicNow() - flushStartTime)) / 1000.0, 0.001);
         xferCombined += writeSec;
         xferStats.append(String
             .format(" Synchronous (fsync) write to disk of " +