Subject: [nfsv4] FYI: Readdir not allowed on NFS pseudo root

From: Stevan Steve Allen <[email-masked]>
Date: Sat, 15 May 2004 08:26:15 -0700

FYI:

Our NFS server sits on top of two operating systems, one UNIX and one non 
hierarchical.  An OS restriction in this environment is READDIR is not 
allowed from the new NFS pseudo root.  Lookup will be allowed. 

A GETATTR for our NFS pseudo root will return a mode with execute 
permission bits on to permit change dir, all read and write mode bits are 
off.

Thanks,
Stevan C. Allen

---

From: Spencer Shepler <[email-masked]>
Date: Sat, 15 May 2004 16:25:49 -0500

On May 15, 2004, at 10:26 AM, Stevan Steve Allen wrote:

>
> FYI:
>
> Our NFS server sits on top of two operating systems, one UNIX and one 
> non hierarchical.  An OS restriction in this environment is READDIR is 
> not allowed from the new NFS pseudo root.  Lookup will be allowed.  
>
> permission bits on to permit change dir, all read and write mode bits 
> are off.

Would you be able to be more specific about the operating
environments for which this server will be available?  This will
allow the client implementors to be able to respond to user
questions about things not working when the client mounts / from
the server.

Spencer

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From: Stevan Steve Allen <[email-masked]>
Date: Sat, 15 May 2004 21:18:53 -0700

Spencer, my intro to Open Systems is still somewhat limited.  Without 
mount support in v4, are you inquiring about Mount in general? 

The operating system is IBM z/OS which contains a flat filesystem with a 
UNIX layer.  The z/OS NFSv3 server will access files directly (filesysA) 
or through the UNIX layer (filesysB).

Basically, z/OS NFSv3 represents two unconnected filesystems where NFSv4 
has introduced a connecting root.

The flat file system is represented by qualified filenames such as 
USER.PROJECTS.NFS.ATTR.  A problem for z/OS NFSv3 is a READDIR of the flat 
filesystem root represents every file in the system.  This is not 
permitted by the z/OS catalog facility due to the output size. 

To address the z/OS 'list all' restriction, z/OS mount support REQUIRES a 
mount on a filename prefix or UNIX directory.  NFSv3 converts flat 
filenames to a hierarchical directory structure.  A mount location may be 
USER or NFS.EXPORTED or /HFS/u/pub allowing a READDIR from this point on. 

The current plan is to return NFS4ERR_NOENT for a READDIR of the NFSv4 
pseudo root.  e.g. the pseudo root will take on the current restrictions 
of the flat filesys root. 

z/OS NFSv3 Pubs:
http://www.ibm.com/servers/eserver/zseries/zos/zos_elefeat.html#n 

Spencer