+ * If someone has not already unmounted this file system,
+ * drain the iput_taskq to ensure all active references to the
+ * zfs_sb_t have been handled only then can it be safely destroyed.
+ */
+ if (zsb->z_os)
+ taskq_wait(dsl_pool_iput_taskq(dmu_objset_pool(zsb->z_os)));
+
+ /*