Can't kill a umount

[Tom Horsley]

On Sun, 6 Sep 2015 12:11:18 -0500 (CDT)
Michael Hennebry wrote:

> Sometimes I get a "drive busy" message from umount,
> which then fails.
> In that case, a file has usually been open.
> Does umount regard this as a different situation?

The device busy means something is actively using it.
The taking a long time to umount means no one is
actively using it, but the in memory buffers haven't
been completely flushed.