HDFS-7939. Two fsimage_rollback_* files are created which are not deleted after rollback. (Contributed by J.Andreina)

(cherry picked from commit 987c9e12e184b35a5abab49f4188e22509ad63a5)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -148,6 +148,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8096. DatanodeMetrics#blocksReplicated will get incremented early and
     even for failed transfers (vinayakumarb)
 
+    HDFS-7939. Two fsimage_rollback_* files are created which are not deleted
+    after rollback. (J.Andreina via vinayakumarb)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImage.java

@@ -711,6 +711,8 @@ public class FSImage implements Closeable {
         true);
     // purge all the checkpoints after the marker
     archivalManager.purgeCheckpoinsAfter(NameNodeFile.IMAGE, ckptId);
+    // HDFS-7939: purge all old fsimage_rollback_*
+    archivalManager.purgeCheckpoints(NameNodeFile.IMAGE_ROLLBACK);
     String nameserviceId = DFSUtil.getNamenodeNameServiceId(conf);
     if (HAUtil.isHAEnabled(conf, nameserviceId)) {
       // close the editlog since it is currently open for write