[SPARK-24107][CORE] ChunkedByteBuffer.writeFully method has not reset the limit value

core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala

@@ -63,10 +63,12 @@ private[spark] class ChunkedByteBuffer(var chunks: Array[ByteBuffer]) {
    */
   def writeFully(channel: WritableByteChannel): Unit = {
     for (bytes <- getChunks()) {
+      val limit = bytes.limit()
       while (bytes.remaining() > 0) {
         val ioSize = Math.min(bytes.remaining(), bufferWriteChunkSize)
         bytes.limit(bytes.position() + ioSize)
         channel.write(bytes)
+        bytes.limit(limit)
       }
     }
   }

core/src/test/scala/org/apache/spark/io/ChunkedByteBufferSuite.scala

@@ -56,6 +56,12 @@ class ChunkedByteBufferSuite extends SparkFunSuite {
     assert(chunkedByteBuffer.getChunks().head.position() === 0)
   }
 
+  test("writeFully() can write buffer which is larger than bufferWriteChunkSize correctly") {
+    val chunkedByteBuffer = new ChunkedByteBuffer(Array(ByteBuffer.allocate(80*1024*1024)))
+    chunkedByteBuffer.writeFully(new ByteArrayWritableChannel(chunkedByteBuffer.size.toInt))
+    assert(chunkedByteBuffer.getChunks().head.position() === 0)
+  }
+
   test("toArray()") {
     val empty = ByteBuffer.wrap(Array.empty[Byte])
     val bytes = ByteBuffer.wrap(Array.tabulate(8)(_.toByte))