PolicyKit confusion

Roland Smith rsmith at xs4all.nl
Sat Dec 24 01:35:32 UTC 2011

On Sat, Dec 24, 2011 at 09:57:38AM +1000, Da Rock wrote:
> > FreeBSD be default already does buffering in the VFS layer (unless you turn
> > that off). I don't think that adding more buffering would help. It might even
> > make matters worse. If data is buffered and not immediately written to the USB
> > stick, it will show no activity. This might even give the user a false
> > impression it is finished...
> That there is exactly the problem. Any way to prevent that though?

Yes. Using the '-o sync' option with mount. To the best of my understanding
that means that a write action will be executed immediately and that write(2)
will not return until it is finished.

> No, I hadn't considered that scenario. Thats why these lists provide a 
> great sounding board :)

It is a heck of a problem. Distributed filesystems like Coda
[http://en.wikipedia.org/wiki/Coda_%28file_system%29] might offer a partial
solution. But it doesn't seem like they're being widely used.

> > The only sane way to handle this is for the application to get an error from
> > the next write reporting that the filesystem has disappeared. Which it should
> > then report to the user because that's the person that pulled the plug, so to
> > speak.
> Man, What a mess! The real solution is to keep the light flashing until 
> all the data written to disk.

The abovementioned -o sync option will do that for you.

The price is that the write syscall will block until it is finished. This
might render the application performing it unresponsive during that time.

> > All the mayor players in this drama, hal, policykit and dbus are maintained by
> > gnome at . In practice that _might_ mean that no single person cares enough to
> > care and feed them.
> >
> Ahh. Now that may explain some things. But by your meaning are you 
> talking about the software development itself or the developers? LOL

What I mean here is that there are no dedicated maintainers for the FreeBSD
ports. When that is the case, that maintainer address of a port is usually
that of a relevant mailing list. That way problems with such a port at least
get the attention of people with relevant interests.

As for the original developers, who knows? IMNSHO their solutions look overly
complex, but I haven't looked at the problem they try to solve because it's
not a problem that bothers me. And I'm kind of allergic to desktop
environments. Over the years I've tried several window managers, but I keep
coming back to good old FVWM. :-)

R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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