2009/11/2 Alexander Motin <mav@freebsd.org>:
> Author: mav
> Date: Sun Nov 1 11:31:06 2009
> New Revision: 198748
> URL: http://svn.freebsd.org/changeset/base/198748
>
> Log:
> MFp4:
> Fix reference counting bug, when device unreferenced before then
> invalidated. To do it, do not handle validity flag as another
> reference, but explicitly modify reference count each time flag is
> modified.
>
> Discovered by: thompsa
Thanks!