HDFS-8845. DiskChecker should not traverse the entire tree (Chang Li via Colin P. McCabe)

(cherry picked from commit ec183faadcf7edaf432aca3b25d24215d505c2ec)

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

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

@@ -32,6 +32,9 @@ Release 2.7.3 - UNRELEASED
 
   OPTIMIZATIONS
 
+    HDFS-8845. DiskChecker should not traverse the entire tree (Chang Li via
+    Colin P. McCabe)
+
   BUG FIXES
 
     HDFS-9289. Make DataStreamer#block thread safe and verify genStamp in

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java

@@ -301,7 +301,7 @@ class BlockPoolSlice {
   }
 
   void checkDirs() throws DiskErrorException {
-    DiskChecker.checkDirs(finalizedDir);
+    DiskChecker.checkDir(finalizedDir);
     DiskChecker.checkDir(tmpDir);
     DiskChecker.checkDir(rbwDir);
   }