MFV r353628:
10842 Mutex leak in dsl_dataset_hold_obj()
illumos/illumos-gate@ad027c0ff9612bff8f47b43d8561da627f80cd29
https://github.com/illumos/illumos-gate/commit/ad027c0ff9612bff8f47b43d8561da627f80cd29
https://www.illumos.org/issues/10842
ZoL d10b2f1d35b Mutex leak in dsl_dataset_hold_obj()
Portions contributed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Author: Jorgen Lundman <lundman@lundman.net>
Obtained from: illumos, ZoL
MFC after: 15 days