HDFS-12245. Fix INodeId javadoc

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

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

@@ -21,9 +21,9 @@ import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.util.SequentialNumber;
 
 /**
- * An id which uniquely identifies an inode. Id 1 to 1000 are reserved for
+ * An id which uniquely identifies an inode. Id 1 to 16384 are reserved for
  * potential future usage. The id won't be recycled and is not expected to wrap
- * around in a very long time. Root inode id is always 1001. Id 0 is used for
+ * around in a very long time. Root inode id is always 16385. Id 0 is used for
  * backward compatibility support.
  */
 @InterfaceAudience.Private
@@ -32,8 +32,8 @@ public class INodeId extends SequentialNumber {
    * The last reserved inode id. InodeIDs are allocated from LAST_RESERVED_ID +
    * 1.
    */
-  public static final long LAST_RESERVED_ID = 2 << 14 - 1;
-  public static final long ROOT_INODE_ID = LAST_RESERVED_ID + 1;
+  public static final long LAST_RESERVED_ID = 1 << 14; // 16384
+  public static final long ROOT_INODE_ID = LAST_RESERVED_ID + 1; // 16385
   public static final long INVALID_INODE_ID = -1;
 
   INodeId() {