Re: [PATCH] rpc.idmapd dies with 'I/O possible'

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

On Mon, May 16, 2011 at 10:23:12AM -0400, Steve Dickson wrote:
> 
> 
> On 05/16/2011 09:38 AM, Luca Giuzzi wrote:
> > Dear All,
> >  we have had problems on some of our machines (all Fedora 14), where
> > rpc.idmapd used to die with an `I/O possible' message at (basically)
> > random times. A strace suggested the issue being in nfsopen() where a
> > signal type is reset before notification is disabled; a signal at just
> > the right time might be the cause of the problem; see
> > https://bugzilla.redhat.com/show_bug.cgi?id=684308
> > I am now proposing the (trivial) patch to the list as well.
> > 
> > Best Regards,
> >   luca giuzzi
> > 
> > --- nfs-utils-1.2.3/utils/idmapd/idmapd.c.orig	2011-05-13
> > 16:27:08.000000000 +0200
> > +++ nfs-utils-1.2.3/utils/idmapd/idmapd.c	2011-05-13 16:27:16.000000000 +0200
> > @@ -778,8 +778,8 @@ nfsopen(struct idmap_client *ic)
> >  	} else {
> >  		event_set(&ic->ic_event, ic->ic_fd, EV_READ, nfscb, ic);
> >  		event_add(&ic->ic_event, NULL);
> > -		fcntl(ic->ic_dirfd, F_SETSIG, 0);
> >  		fcntl(ic->ic_dirfd, F_NOTIFY, 0);
> > +		fcntl(ic->ic_dirfd, F_SETSIG, 0);
> >  		if (verbose > 0)
> >  			xlog_warn("Opened %s", ic->ic_path);
> >  	}
> I just updated the bz with these questions, but we can have the 
> conversation here...
> 
> I'm just a bit concerned by the fact that there are
> a couple of places that sets F_SETSIG and then sets F_NOTIFY, 
> so does that mean those places are potential race cases as 
> well?

I wondered about that too; looking:

utils/gssd/gssd_main_loop.c:		fcntl(tdi->fd, F_NOTIFY,
		      	DN_CREATE|DN_DELETE|DN_MODIFY|DN_MULTISHOT);

utils/gssd/gssd_proc.c:	fcntl(clp->dir_fd, F_NOTIFY, DN_CREATE | DN_DELETE | DN_MULTISHOT);
utils/idmapd/idmapd.c:		if (fcntl(fd, F_NOTIFY,
			DN_CREATE | DN_DELETE | DN_MODIFY | DN_MULTISHOT) == -1) {
utils/idmapd/idmapd.c:			fcntl(ic->ic_dirfd, F_NOTIFY,
			DN_CREATE | DN_DELETE | DN_MULTISHOT);
utils/idmapd/idmapd.c:		fcntl(ic->ic_dirfd, F_NOTIFY, 0);

So the last is the only one where we're turning notifications *off*.

So I think the patch is OK.

--b.

> 
> Also, after you applied this patch, did the problem go away?
> Finally, how often did this problem occur?
> 
> tia,
> 
> steved.
> 
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