On Mon, 15 Sep 2014 18:08:13 -0400
"J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> On Thu, Aug 28, 2014 at 04:24:43PM -0400, J. Bruce Fields wrote:
> > On Thu, Aug 28, 2014 at 04:01:00PM -0400, J. Bruce Fields wrote:
> > > On Tue, Aug 19, 2014 at 02:38:25PM -0400, Jeff Layton wrote:
> > > > Currently, all of the grace period handling is part of lockd. Eventually
> > > > though we'd like to be able to build v4-only servers, at which point
> > > > we'll need to put all of this elsewhere.
> > > >
> > > > Move the code itself into fs/nfs_common and have it build a grace.ko
> > > > module. Then, rejigger the Kconfig options so that both nfsd and lockd
> > > > enable it automatically.
> > >
> > > Thanks, applying this one for 3.18 indepedently of the others.
> >
> > This code should also be fixed, though.
> >
> > Currently nfsd is recording the grace period as done when its own timer
> > runs out, but then it continuing to accept reclaims until lockd is also
> > done.
>
> I sat down to fix this today then decided there's not a real bug:
>
> All the grace_done upcall really does is throw away any previous clients
> that haven't reclaimed yet.
>
> It's legal to do that as soon as the correct amount of time has passed.
> It's actually OK to continue to allow the grace period to run past that
> point, the only requirement is that all reclaims precede all new opens,
> which the code still does enforce.
>
> So I think it might just be worth a little extra explanation.
>
> --b.
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index a298c3d..ca6f6ee 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4122,8 +4122,23 @@ nfsd4_end_grace(struct nfsd_net *nn)
>
> dprintk("NFSD: end of grace period\n");
> nn->grace_ended = true;
> + /*
> + * If the server goes down again right now, an NFSv4
> + * client will still be allowed to reclaim after it comes back up,
> + * even if it hasn't yet had a chance to reclaim state this time.
> + */
Might even be reasonable to lay out the v4.0/v4.1+ difference here? For
a v4.0 client any lock reclaim will do, but for v4.1+ the client must
have _completed_ reclaim at this point (a'la RECLAIM_COMPLETE)
...or at least that'll be the situation once the patches I sent go in...
> nfsd4_record_grace_done(nn);
> + /*
> + * At this point, NFSv4 clients can still reclaim. But if
> the
> + * server crashes, any that have not yet reclaimed will be
> out
> + * of luck on the next boot.
> + */
> locks_end_grace(&nn->nfsd4_manager);
> + /*
> + * At this point, and once lockd and/or any other containers
> + * exit their grace period, further reclaims aren't permitted
> + * and regular locking can resume.
> + */
> }
>
> static time_t
> --
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ACK, overall. The comments make sense to me and it does clarify things
a bit.
--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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