[nfsv4] Asking for details about OPEN_DOWNGRADE

[Mike Mackovitch]

On Fri, Jun 13, 2008 at 04:58:17PM -0400, Trond Myklebust wrote:
> On Fri, 2008-06-13 at 13:29 -0700, Mike Mackovitch wrote:
> 
> > By explicitly specifying that the behavior described above should not
> > be allowed.  It is clear that the spec is NOT clear about that....
> > otherwise, the spec wouldn't be getting "misinterpreted" by many people.
> > 
> > The text in the OPEN and OPEN_DOWNGRADE descriptions, as well as "Open
> > Upgrade and Downgrade" sections, leads me (and others) to believe that
> > the server only keeps one "OR"ed-together status for that owner and
> > thus sending multiple, redundant OPEN requests (for that owner) was
> > unnecessary.
> 
> I don't see how it can be interpreted that way.

Perhaps that's because you now have a different perspective?  :-)

Apparently the Linux NFS client also interpreted it incorrectly up 
until a couple years ago (2.6.15).

> The texts in section
> 8.11 and in 14.2.19 both take care to talk about a _union_ of the OPEN
> share and deny modes and proper subsets of that union.

See my other responses regarding "in effect" vs. "particular ops sent
to the server".

> The pynfs test suite will even check for this condition, so there is not
> much excuse for claiming ignorance.

Uhh, OK then ... I guess I'll just have to claim stupidity?
After all, everyone knows you should never trust the Solaris NFS
implementation to do things correctly.

Silly me.
--macko