Re: [Tracker] [systemd-devel] How to use cgroups for Tracker?

[Lennart Poettering <mztabzr 0pointer de>]

On Thu, 23.10.14 11:40, Martyn Russell (martyn lanedo com) wrote:

> > > Anyway, please remember that being privileged isn't the only reason
> > > why Tracker can't use fanotify. It's API being fd-based, it works on
> > > existing open files only; e.g. it won't notify file deletes or move
> > > events, among other things. If we want some recursirve monitoring
> > > approach with all CREATE/UPDATE/DELETE/MOVE events, something new
> > > needs to be implemented, or inotify somehow improved to handle that.
> >
> > I don't think fanotify's interface couldn't be fixed to also generate
> > useful events for deletion/moving.
>
> I don't really understand why it was developed as a half complete solution
> if I am honest. It's not as if there are no examples to follow out there
> (FSEvents) and it's not as if we didn't say what our user space requirements
> were at the time.

fanotify may be use in synchronous mode, which is useful for virus
scanners. The asynchronous mode is just an addition on top, but
unfortunately nobody looks after it.

To my knowlegde apple's fsevents stuff isn't really the holy grail as
it basically makes the kernel hang on userspace components. That's the
wrong way round. userpsace may sync on kernel, and userspace on
userspace, but kernel on userspace is just bad design.

> I know it's a hard problem to solve, but if it's not solved with the
> proposed solutions, the kernel developers shouldn't really be accepting
> them.

Well, if it doesn't work, fix it! IIRC you have a business interest in
tracker. Kernel interfaces don't fix themselves magically. They usual
get fixed if somebody scratches his own itch, or if somebody with a
business interest pays somebody to scratch his itch...

All these problems aren't exactly new, are they? They have been
discussed since 5y on and off...

Lennart

-- 
Lennart Poettering, Red Hat