Subject: [nfsv4] [FedFS] XDR encoding of path "/"

From: James Lentini <[email-masked]>
Date: Wed, 13 Oct 2010 10:17:08 -0400 (EDT)

At the BAT, Chuck Lever and I discussed what the pathname4 encoding of 
"/" should be.

In addition to being used by the fs_locations and fs_locations_info 
attributes, the pathname4 format is used by the fedfsNfsPath LDAP 
attribute (see Section 4.2.1.14 of 
draft-ietf-nfsv4-federated-fs-protocol-09), and the FedFsPathName XDR 
type (see draft-ietf-nfsv4-federated-fs-admin-07).

I'm aware of two different approaches to encoding "/".

One interpretation is to encode an array with zero compnent4 values. 
This encoding is a single 32-bit field containing a 0. The Linux NFS 
server and the SNSDB tools use this format.

Another interpretation is to encode an array with one zero-length 
component4 value. The encoding of this is a 32-bit field containing a 
1 followed by a 32-bit field containing a 0.

The Linux NFS client appears to accept both of these encodings for 
"/".

Are there any implementations using a different encoding than the ones 
above?

I'm thinking it would make sense to record these different formats or 
recommend the use of a specific format in one (or both) of the FedFS 
specifications.

-james

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From: "Spencer Shepler" <[email-masked]>
Date: Wed, 13 Oct 2010 09:14:49 -0700

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> James Lentini
> Sent: Wednesday, October 13, 2010 7:17 AM
> To: [email-masked]
> Subject: [nfsv4] [FedFS] XDR encoding of path "/"
> 
> 
> At the BAT, Chuck Lever and I discussed what the pathname4 encoding of "/"
> should be.
> 
> attribute (see Section 4.2.1.14 of draft-ietf-nfsv4-federated-fs-protocol-
> 09), and the FedFsPathName XDR type (see draft-ietf-nfsv4-federated-fs-
> admin-07).
> 
> The Linux NFS client appears to accept both of these encodings for "/".
> 

Good point. FedFS specification is a good choice.  As to the specifics,
I would mildly prefer both be specified as acceptable encodings.

Spencer

---

From: <[email-masked]>
Date: Wed, 13 Oct 2010 14:04:21 -0400

It seems like the right place is RFC3530bis.  We should of put it in
RFC3530 and then we wouldn't have two forms to deal with.  But that's
life.

I have no objection to this being mentioned in a FedFS document but
since pathname4 is introduced by RFC3530, this piece of clarification
belongs in RFC3530bis. 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Spencer Shepler
Sent: Wednesday, October 13, 2010 12:15 PM
To: 'James Lentini'; [email-masked]
Subject: Re: [nfsv4] [FedFS] XDR encoding of path "/"

> At the BAT, Chuck Lever and I discussed what the pathname4 encoding of
"/"
> attribute (see Section 4.2.1.14 of
draft-ietf-nfsv4-federated-fs-protocol-
"/".

Spencer

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---

From: James Lentini <[email-masked]>
Date: Wed, 13 Oct 2010 17:09:51 -0400 (EDT)

> RFC3530 and then we wouldn't have two forms to deal with.  But that's

A clarification in RFC3530bis would be great.

> since pathname4 is introduced by RFC3530, this piece of clarification

The FedFS admin protocol defines an XDR type, FedFsPathName, with the 
same structure as a pathname4. For that reason, I could imagine a note 
about this in draft-ietf-nfsv4-federated-fs-admin. If this issue is 
discussed in RFC3530bis, then a reference in 
draft-ietf-nfsv4-federated-fs-admin to the relevant text RFC3530bis 
would make sense to me.

What would the text in RFC3530bis say about this?

> Of

---

From: <[email-masked]>
Date: Thu, 14 Oct 2010 05:48:23 -0400

Since your document will be going first, I think it does make sense to
put text relative to this issue in federated-fs-admin.  If this is a new
type, I think it would simplify things to simply say that it had to be a
zero-length array for "/".  Dealing with one value is easier than
dealing with two.

You could mention that this issue is not addressed in RFC3530 and that
if it is addressed in a future NFSv4.0 specification (i.e.
RFC3530{bis,tris,...}), any greater liberality regarding other ways to
encode this for pathname4 would not apply to FedFsPathName.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of James Lentini
Sent: Wednesday, October 13, 2010 5:10 PM
To: Noveck, David
Cc: [email-masked]
Subject: Re: [nfsv4] [FedFS] XDR encoding of path "/"