Devd event from GEOM?

[Robert Watson]

On Sun, 30 Jan 2005, Poul-Henning Kamp wrote:

> In message <20050130161323.5e25414e at Magellan.Leidinger.net>, Alexander Leidinger writes:
> 
> >Let's take a CD for example, when it arrives the auto-mounter mounts it.
> >Fine, but the CD is locked then. What do we do when we want to remove
> >the CD? Or another example, an USB stick. The hardware isn't locked, but
> >when we just remove it, we're calling for a kernel panic.
> 
> Now that local-storage filesystems are GEOM users, we can actually get
> the "orphan" event from GEOM communicated to the filesystem which can
> then take proper evasive action. No filesystem has implemented this yet. 

I think tolerance of hard removal faults will always be a tricky issue --
we can clearly handle it better than we do today.  The user losing data is
fine: if you don't want to lose data, you have to arrange for a clean
unmount.  However, today's panic is a bit extreme. 

The good news is that soft eject is a lot easier to handle, as it's more
of a question of signalling and management than hard technical issues in
how to tear down state at a bad moment in the kernel. 

Robert N M Watson