MAPREDUCE-6063. Correct spill size calculation for spills wrapping the circular buffer. Contributed by zhihai xu

CHANGES.txt

@@ -242,6 +242,9 @@ Release 1.3.0 - unreleased
     MAPREDUCE-6012. DBInputSplit creates invalid ranges on Oracle. 
     (Wei Yan via kasha)
 
+    MAPREDUCE-6063. Correct spill size calculation for spills wrapping the
+    circular buffer. (zhihai xu via cdouglas)
+
 Release 1.2.2 - unreleased
 
   INCOMPATIBLE CHANGES

src/mapred/org/apache/hadoop/mapred/MapTask.java

@@ -1387,7 +1387,7 @@ class MapTask extends Task {
       //buffer + header lengths for the partitions
       long size = (bufend >= bufstart
           ? bufend - bufstart
-          : (bufvoid - bufend) + bufstart) +
+          : (bufvoid - bufstart) + bufend) +
                   partitions * APPROX_HEADER_LENGTH;
       FSDataOutputStream out = null;
       try {