HDFS-17291. DataNode metric bytesWritten is not totally accurate in some situations. (#6360). Contributed by farmmamba.

Reviewed-by: huangzhaobo <huangzhaobo99@126.com>
Signed-off-by:  Shuyan Zhang <zhangshuyan@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java

@@ -842,7 +842,7 @@ class BlockReceiver implements Closeable {
           
           replicaInfo.setLastChecksumAndDataLen(offsetInBlock, lastCrc);
 
-          datanode.metrics.incrBytesWritten(len);
+          datanode.metrics.incrBytesWritten(numBytesToDisk);
           datanode.metrics.incrTotalWriteTime(duration);
 
           manageWriterOsCache(offsetInBlock, seqno);