HDFS-13545. "guarded" is misspelled as "gaurded" in FSPermissionChecker.java. Contributed by Jianchao Jia.

(cherry picked from commit 0e3c31579d1c733decfb9b00721bdc7b86be60f2)

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

@@ -44,7 +44,7 @@ import org.apache.hadoop.security.UserGroupInformation;
  * The state of this class need not be synchronized as it has data structures that
  * are read-only.
  * 
- * Some of the helper methods are gaurded by {@link FSNamesystem#readLock()}.
+ * Some of the helper methods are guarded by {@link FSNamesystem#readLock()}.
  */
 public class FSPermissionChecker implements AccessControlEnforcer {
   static final Log LOG = LogFactory.getLog(UserGroupInformation.class);