Fatal trap 12 if you unmount detached umass device

[Andre Guibert de Bruet]

On Sun, 3 Jul 2005, Yuriy Tsibizov wrote:

> It should be easy to reproduce if you don't follow
> attach/mount/unmount/detach order:
>
> 1. attach usb storage device
> 2. mount it
> 3. detach it
> 4. unmount it.

This topic has been discussed at length on this list. Please search the 
archives. Conclusions that can be drawn:

1. Don't do that (If you're going to do it, try umount -f).
2a. Disabling write caching is the only way to get USB storage to be near 
hot-pluggable. Major write performance degradation is guaranteed.
2b. A non-trivial amount of work is needed to fix this. A suggested fix 
would be to rework the way that GEOM and CAM work together so that 
additional state information is passed (In the past, this topic has 
brought about two dozen Trek bikes, four bike racks and a lovely 
$COLOR-painted bikeshed).

Andy

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