Hi  I got the answer from EMC technical engineer.  [answer] It's expected. Since as for mount process, NFSv3 and NFSv4 are difference.  In NFSv3, client must rely on auxiliary protocol, the mount protocol to request a list of server's exports and obtain root filehandle of a given export. And in NFSv4 uses the virtual file system to present the serer's export and associated root filehandles to the client.  NFSv4 don't have mountd process during the mounting so the option mount access to sub directories disable will not limit access when using NFSv4.
Hi,  I have an problem about NFS export on OneFS 7.2.1.1. Although I checked "Enable mount access to subdirectories...." when creating NFS export, I can mount subdirectories.  I found this problem resolved on OneFS 6.5.  document : OneFS 6.5 Release Note   p11 [URL]   Could you tell me how to investigate this problem? 
Why I can mount NFS export subdirectories?