Date: Sat, 18 Feb 2006 22:32:21 -0800
From: Andrew Morton <akpm@osdl.org>
To: Phillip Susi <psusi@cfl.rr.com>
Cc: stern@rowland.harvard.edu, pavel@suse.cz, torvalds@osdl.org,
       mrmacman_g4@mac.com, alon.barlev@gmail.com,
       linux-kernel@vger.kernel.org, linux-pm@lists.osdl.org
Subject: Re: Flames over -- Re: Which is simpler?
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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.
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