We have exclusive access to our zfsdev state object in this section
until it is invalidated by setting zs_minor to -1, so we can destroy
the state without taking a lock if we do the invalidation last, after
a member to ensure correct ordering.
While here, strengthen the assertions that zs_minor is valid when we
enter.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes#11751
43efd5625b