HDFS-9280. Document NFS gateway export point parameter. Contributed by Xiao Chen.

Change-Id: I1cea610c31301d793db3c9ca4dae86d0e5d2d64b

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

@@ -1591,6 +1591,8 @@ Release 2.8.0 - UNRELEASED
 
     HDFS-9253. Refactor tests of libhdfs into a directory. (wheat9)
 
+    HDFS-9280. Document NFS gateway export point parameter. (Xiao Chen via zhz)
+
   BUG FIXES
 
     HDFS-7501. TransactionsSinceLastCheckpoint can be negative on SBNs.

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsNfsGateway.md

@@ -195,6 +195,14 @@ It's strongly recommended for the users to update a few configuration properties
 
             log4j.logger.org.apache.hadoop.oncrpc=DEBUG
 
+*   Export point. One can specify the NFS export point of HDFS. Exactly one export point is supported.
+    Full path is required when configuring the export point. By default, the export point is the root directory "/".
+
+        <property>
+          <name>nfs.export.point</name>
+          <value>/</value>
+        </property>
+
 Start and stop NFS gateway service
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