HDFS-17344. Last packet will be splited into two parts when write block.

Author: hfutatzhanghb

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java

@@ -539,6 +539,9 @@ protected void adjustChunkBoundary() {
       int psize = 0;
       if (blockSize == getStreamer().getBytesCurBlock()) {
         psize = writePacketSize;
+      } else if (blockSize - getStreamer().getBytesCurBlock() + PacketHeader.PKT_MAX_HEADER_LEN
+          < writePacketSize) {
+        psize = (int)(blockSize - getStreamer().getBytesCurBlock()) + PacketHeader.PKT_MAX_HEADER_LEN;
       } else {
         psize = (int) Math
             .min(blockSize - getStreamer().getBytesCurBlock(), writePacketSize);