Re: [PATCH v2] locks: Filter /proc/locks output on proc pid ns

From: J. Bruce Fields
Date: Wed Aug 03 2016 - 11:14:30 EST


On Wed, Aug 03, 2016 at 06:00:18PM +0300, Nikolay Borisov wrote:
>
>
> On 08/03/2016 05:54 PM, Pavel Emelyanov wrote:
> > On 08/03/2016 05:17 PM, Nikolay Borisov wrote:
> >>
> >>
> [SNIP]
> >>
> >> [CCing some people from openvz/CRIU]
> >
> > Thanks :)
> >
> >> My train of thought was "we should have means which would be the one
> >> universal truth about everything and this would be a process in the
> >> init_pid_ns". I don't have strong preference as long as I'm not breaking
> >> userspace. As I said before - I think the CRIU guys might be using that
> >> interface.
> >
> > This particular change won't break us mostly because we've switched to
> > reading the /proc/pid/fdinfo/n files for locks.
>
> [thinking out loud here]
>
> I've never actually looked into those files but now that I have it seems
> to make sense to also switch 'lsof' to actually reading the locks from
> the available pids directories rather than relying on the global
> /proc/locks interface. Oh well :)

Digging around... Oh, I see, there's an optional 'lock:..' line in
/proc/[pid]/fdinfo/[pid] file, is that what you're looking at? I'd
forgotten. Yeah, maybe that would make more sense long term.

--b.

>
> [/thinking out loud here]
>
> >
> > -- Pavel
> >
> >>>
> >>>>>> + && (proc_pidns != ns_of_pid(fl->fl_nspid)))
> >>>>> + return 0;
> >>>> +
> >>>>> lock_get_status(f, fl, iter->li_pos, "");
> >>>>
> >>>>> list_for_each_entry(bfl, &fl->fl_block, fl_block)
> >>>
> >> .
> >>
> >
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