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

[Ryan Stone]

On Wed, May 6, 2015 at 5:28 PM, NGie Cooper <yaneurabeya at gmail.com> wrote:

> On Wed, May 6, 2015 at 1:49 PM, Ryan Stone <rysto32 at gmail.com> wrote:
> > 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.
> >
> > A co-worker has been looking at this but I don't feel that we understand
> > the problem well enough to produce a real fix.  All that we've been doing
> > so far is papering over the explicit panics without having a full
> > understanding of what we're doing.
>
> What version are you working on and how is the USB stick mounted (/, /mnt,
> etc)?
> Thanks!
>

Most of our testing was with 8.2, but we also did testing with some version
of FreeBSD 10 (unfortunately I can't find a reference to a specific
version).

It's mounted on /mnt.  I'm not expecting us to survive the loss of the root
filesystem. :)