Re: Flames over -- Re: Which is simpler?

Andrew Morton
2006-02-19T06:32:21Z

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Phillip Susi <psusi@cfl.rr.com> wrote:
>
> > But I suspect we could do an even better job if we did that in userspace.
> >
> > The logic to determine whether the new device is the same as the old device
> > can be arbitrarily complex, with increasing levels of success. Various
> > heuristics can be applied, some of which will involve knowledge of
> > filesystem layout, etc.
> >
> > So would it not be possible to optionally punt the device naming decision
> > up to the hotplug scripts? So code up there can go do direct-IO reads of
> > the newly-present blockdev, use filesytem layout knowledge, peek at UUIDs,
> > superblocks, disk labels, partition tables, inode numbering, etc? Go look
> > up a database, work out what that filesystem was doing last time we saw it,
> > etc?
> >
> > We could of course add things to the filesystems to help this process, but
> > it'd be good if all the state tracking and magic didn't have to be locked
> > up in the kernel.
>
>
> Hrm... interesting but sounds like that could be sticky. For instance,
> what if the user script that does the verifying happens to be ON the
> volume to be verified?

Well that would be a bug. Solutions would be a) don't put the scripts on a
removable/power-downable device or b) use tmpfs.