HDFS-8175. Provide information on snapshotDiff for supporting the comparison between snapshot and current status (Contributed by J.Andreina)

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

@@ -678,6 +678,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8187. Remove usage of "-setStoragePolicy" and "-getStoragePolicy" using
     dfsadmin cmd (as it is not been supported) (J.Andreina via vinayakumarb)
 
+    HDFS-8175. Provide information on snapshotDiff for supporting the comparison
+    between snapshot and current status (J.Andreina via vinayakumarb)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsSnapshots.xml

@@ -257,6 +257,10 @@
       <tr><td>fromSnapshot</td><td>The name of the starting snapshot.</td></tr>
       <tr><td>toSnapshot</td><td>The name of the ending snapshot.</td></tr>
     </table></li>
+    <p>
+      Note that snapshotDiff can be used to get the difference report between two snapshots, or between
+      a snapshot and the current status of a directory.Users can use "." to represent the current status.
+    </p>
     <li>Results:
       <table>
         <tr><td>+</td><td>The file/directory has been created.</td></tr>