usb/84336: [usb] [reboot] instant system reboot when unmounting a powered off/unplugged+replugged USB device

[Peter Jeremy]

On Sat, Jan 26, 2008 at 12:54:54PM +0100, Henrik Gulbrandsen wrote:
>At this point, only the file systems need to be updated. The cleanest
>way to handle things may be to have GEOM automatically unmount them at
>orphaning. Until that's done, however, unmounting from user space via
>devd seems to be a reasonable approach.

This approach doesn't work because GEOM doesn't know the drive has
gone away until it's no longer present.  At that point it's too late
to write unflushed buffers.  And a devfs-triggered forced unmount does
not address the issue of in-flight I/O's between when the media goes
away and the filesystem is unmounted.

This problem is one of a number of problems within FreeBSD where there
is a disconnect between the people who want the problem solved and those
with the skills to actually solve the problem.  This is a side-effect of
FreeBSD being a volunteer project and it's not clear how to fix this.

-- 
Peter Jeremy
Please excuse any delays as the result of my ISP's inability to implement
an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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