HDFS-8108. Fsck should provide the info on mandatory option to be used along with -blocks ,-locations and -racks. Contributed by J.Andreina.

(cherry picked from commit 4b00ae5c113a9a8bd2a300f6d88897b932eeb94f)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSck.java

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

@@ -345,6 +345,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8222. Remove usage of "dfsadmin -upgradeProgress" from document which
     is no longer supported. (J.Andreina via aajisaka)
 
+    HDFS-8108. Fsck should provide the info on mandatory option to be used along with "-blocks ,
+    -locations and -racks" (J.Andreina via umamahesh)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSck.java

@@ -89,9 +89,10 @@ public class DFSck extends Configured implements Tool {
       + "snapshottable directories under it\n"
       + "\t-list-corruptfileblocks\tprint out list of missing "
       + "blocks and files they belong to\n"
-      + "\t-blocks\tprint out block report\n"
-      + "\t-locations\tprint out locations for every block\n"
-      + "\t-racks\tprint out network topology for data-node locations\n"
+      + "\t-files -blocks\tprint out block report\n"
+      + "\t-files -blocks -locations\tprint out locations for every block\n"
+      + "\t-files -blocks -racks" 
+      + "\tprint out network topology for data-node locations\n"
       + "\t-storagepolicies\tprint out storage policy summary for the blocks\n\n"
       + "\t-blockId\tprint out which file this blockId belongs to, locations"
       + " (nodes, racks) of this block, and other diagnostics info"