Subject: [nfsv4] Question about Attribute 60: change_policy.

From: Trond Myklebust <[email-masked]>
Date: Fri, 14 Dec 2007 12:11:06 -0500

Should this attribute perhaps also change when things like SECINFO
policy is updated and/or the administrator changes the filesystem policy
from read-only to read-write?

The reason I think this can be useful is that currently if you get a
WRONGSEC error when crossing into a new directory, you basically do not
know if the administrator has changed the secinfo policy on the parent
directory, or if the administrator has set a different secinfo policy on
the child. Currently, afaics, in order to resolve that question, you
need to call SECINFO on both the parent and the child (am I wrong?).
Doing it only on the child is not sufficient, since neither PUTFH, nor
SECINFO may return WRONGSEC to indicate that the policy on the parent
directory's filehandle has changed.

If, however, the client knows that the change_policy attribute is bumped
whenever the administrator changes filesystem policy, then it can
optimise away the SECINFO call on the parent in most cases.

IOW: I'm suggesting that the client can basically use change_policy as a
test for whether or not '/etc/exports' (or whatever equivalent the
server uses to manage filesystem export policy) has changed.

Cheers
  Trond

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From: "Noveck, Dave" <[email-masked]>
Date: Fri, 14 Dec 2007 12:27:27 -0500

That sounds sensible to me.

-----Original Message-----
From: Trond Myklebust [mailto:[email-masked]] 
Sent: Friday, December 14, 2007 12:11 PM
To: [email-masked]
Subject: [nfsv4] Question about Attribute 60: change_policy.

Cheers
  Trond