Re: [PATCH v2 0/5] nfsd: support for lifting grace period early

[Trond Myklebust <trondmy@gmail.com>]

On Fri, Sep 26, 2014 at 3:46 PM, J. Bruce Fields <bfields@fieldses.org> wrote:
>
> As I understand it, the rule for the client is: you're allowed to
> reclaim only the set locks that you held previously, where "the set of
> locks you held previously" is "the set of locks held by the clientid
> which last managed to send a reclaim OPEN or OPEN_CONFIRM".  So for
> example once client1 sends that unrelated OPEN reclaim it's giving up on
> anything else it doesn't manage to reclaim this time around.

The rule for the client is very simple: "You may attempt to reclaim
any locks that were held immediately prior to the reboot of the
server."
It doesn't matter how those locks were established (ordinary OPEN,
delegated open, reclaim open, LOCK, reclaim lock...).

However if the server reboots and the client did not manage to
re-establish a lease (SETCLIENTID+SETCLIENTID_CONFIRM and/or
EXCHANGE_ID+CREATE_SESSION) before the second reboot, then it is the
server's responsibility to block that client from reclaiming any
locks, since the client has no way to know how many times the server
has rebooted.
Ditto, of course, if the client tries to reclaim any locks outside the
grace period and the server isn't tracking whether or not those locks
have been handed out to another client.