Re: fcntl(F GETLEASE) semantics??

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, Aug 11, 2005 at 10:06:31AM -0400, Trond Myklebust wrote:
> The NFSv4 spec explicitly states that
> 
>   When a client has a read open delegation, it may not make any changes
>   to the contents or attributes of the file but it is assured that no
>   other client may do so.

I don't understand the motivation for that requirement.  As long as the
server sends write opens to the server, and doesn't try to cache them
locally, I don't see why it shouldn't be left up to the server whether
to allow writes on a read-delegated file.

> so NFSv4 cannot currently support this behaviour. If CIFS supports it,
> then maybe we have a case for going to the IETF and asking for a
> clarification to implement the same behaviour in NFSv4.

I think we could implement the correct NFSv4 delegation behaviour using
either lease semantic.

In any case, I haven't seen a real argument for reverting to the old
behaviour.  I'd rather see an established standard, or a correct
real-world application that fails, not just some arbitrary test.

--b.