Re: fanotify - overall design before I start sending patches

Pavel Machek
2009-08-06T10:11:09Z

On Wed 2009-08-05 17:46:16, Tvrtko Ursulin wrote:
> On Wednesday 05 August 2009 03:05:34 Pavel Machek wrote:
> > BTW my -@suse.cz address no longer works. pavel@ucw.cz should be ok.
> >
> > > If a FAN_ACCESS_PERM or FAN_OPEN_PERM event is received the listener
> > > must send a response before the 5 second timeout. If no response is
> > > sent before the 5 second timeout the original operation is allowed. If
> > > this happens too many times (10 in a row) the fanotify group is evicted
> > > from the kernel and will not get any new events. Sending a response is
> > > done using the setsockopt() call with the socket options set to
> > > FANOTIFY_ACCESS_RESPONSE. The buffer should contain a structure like:
> >
> > The timeout part of interface is very ugly. Will fanotify users have
> > to be realtime/mlocked?
>
> Why do you think it is very ugly?

Do I need to explain?

> Just to make sure you haven't missed this - it is not that they have to
> complete the whole operation before the timeout period (since you mention
> realtime/mlock I suspect this is what you think?), but _during_ the operation
> they have to show that they are active by sending something like keep alive
> messages.
>
> Or you are worried about failing to meet even that on a loaded system? There
> has to be something like this otherwise hung userspace client would kill the
> whole system.

Of course, I'm worried about failing to meet this on loaded
system. And the fact that I _have_ to worry about that means that
interface is ugly/broken.
Pavel
--
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