What's required to make removal of a mounted USB stick safe?

[Edward Tomasz Napierała]

Dnia 6 maj 2015 o godz. 22:49 Ryan Stone <rysto32 at gmail.com> napisał(a):

> Currently FreeBSD stands a fair chance at panicking if a mounted USB drive
> is removed while I/O is in flight.  Does anybody know what work is involved
> to have the kernel safely recover from this case?  Losing data from the
> drive is expected of course but there's no reason that the entire kernel
> has to crash.

I've spent some time on this few years ago, and got it to work, except for one case: UFS with softupdates.  It's possible that some regressions have been introduced since then.  What's the filesystem?  Do you have a backtrace?