Re: [nfs-utils PATCH] sm-notify: ending the grace period early should be configurable

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

On Mon, Mar 13, 2017 at 05:10:26PM -0400, Scott Mayhew wrote:
> On Mon, 13 Mar 2017, J. Bruce Fields wrote:
> 
> > On Fri, Mar 10, 2017 at 04:39:19PM -0500, Scott Mayhew wrote:
> > > sm-notify's early ending of the grace period when it has no hosts to
> > > notify can cause problems in some high availability configurations,
> > > which may be running one sm-notify per floating IP address in the
> > > cluster.
> > 
> > So, there may be no hosts associated with this floating IP, but there
> > may be with another?
> 
> Exactly.  What was happening in my testing was that clients would
> receive and respond to a NOTIFY, and would immediately send a LOCK with
> reclaim=yes but would get NFSERR_NO_GRACE in return.
> 
> BTW I had a cluster with this change running at Connectathon.

Great, thanks.--b.

> 
> -Scott
> > 
> > > This commit makes that behavior configurable via the
> > > nfs.conf (I don't think having a corresponding command line option
> > > would be particularly useful, hence none was added).
> > 
> > And, I see that you're defaulting it to on to match existing behavior.
> > 
> > Makes sense to me, ACK.--b.
> > 
> > > 
> > > Signed-off-by: Scott Mayhew <smayhew@redhat.com>
> > > ---
> > >  nfs.conf                  |  1 +
> > >  utils/statd/sm-notify.c   |  6 +++++-
> > >  utils/statd/sm-notify.man | 18 ++++++++++++++++++
> > >  3 files changed, 24 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/nfs.conf b/nfs.conf
> > > index 81ece06..690645c 100644
> > > --- a/nfs.conf
> > > +++ b/nfs.conf
> > > @@ -65,6 +65,7 @@
> > >  # retry-time=900
> > >  # outgoing-port=
> > >  # outgoing-addr=
> > > +# lift-grace=y
> > >  #
> > >  #[svcgssd]
> > >  # principal=
> > > diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
> > > index 623213e..0c6766f 100644
> > > --- a/utils/statd/sm-notify.c
> > > +++ b/utils/statd/sm-notify.c
> > > @@ -45,6 +45,8 @@
> > >  
> > >  #define NLM_END_GRACE_FILE	"/proc/fs/lockd/nlm_end_grace"
> > >  
> > > +int lift_grace = 1;
> > > +
> > >  struct nsm_host {
> > >  	struct nsm_host *	next;
> > >  	char *			name;
> > > @@ -494,6 +496,7 @@ main(int argc, char **argv)
> > >  	opt_max_retry = conf_get_num("sm-notify", "retry-time", opt_max_retry / 60) * 60;
> > >  	opt_srcport = conf_get_str("sm-notify", "outgoing-port");
> > >  	opt_srcaddr = conf_get_str("sm-notify", "outgoing-addr");
> > > +	lift_grace = conf_get_bool("sm-notify", "lift-grace", lift_grace);
> > >  	s = conf_get_str("statd", "state-directory-path");
> > >  	if (s && !nsm_setup_pathnames(argv[0], s))
> > >  		exit(1);
> > > @@ -570,7 +573,8 @@ usage:		fprintf(stderr,
> > >  	(void)nsm_retire_monitored_hosts();
> > >  	if (nsm_load_notify_list(smn_get_host) == 0) {
> > >  		xlog(D_GENERAL, "No hosts to notify; exiting");
> > > -		nsm_lift_grace_period();
> > > +		if (lift_grace)
> > > +			nsm_lift_grace_period();
> > >  		return 0;
> > >  	}
> > >  
> > > diff --git a/utils/statd/sm-notify.man b/utils/statd/sm-notify.man
> > > index bb7f6e0..cfe1e4b 100644
> > > --- a/utils/statd/sm-notify.man
> > > +++ b/utils/statd/sm-notify.man
> > > @@ -241,6 +241,24 @@ These have the same effect as the command line options
> > >  .B v
> > >  respectively.
> > >  
> > > +An additional value recognized in the
> > > +.B [sm-notify]
> > > +section is
> > > +.BR lift-grace .
> > > +By default,
> > > +.B sm-notify
> > > +will lift lockd's grace period early if it has no hosts to notify.
> > > +Some high availability configurations will run one
> > > +.B sm-notify
> > > +per floating IP address.  In these configurations, lifting the
> > > +grace period early may prevent clients from reclaiming locks.
> > > +.RB "Setting " lift-grace " to " n
> > > +will prevent
> > > +.B sm-notify
> > > +from ending the grace period early.
> > > +.B lift-grace
> > > +has no corresponding command line option.
> > > +
> > >  The value recognized in the
> > >  .B [statd]
> > >  section is
> > > -- 
> > > 2.7.4
> > > 
> > > --
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