Re: fanotify - overall design before I start sending patches

Tvrtko Ursulin
2009-08-05T16:46:21Z

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?

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.

Tvrtko