hammer_lock_upgrade
int hammer_lock_upgrade(struct hammer_lock *lock, int shcount);
error = hammer_lock_upgrade(&cursor->parent->lock, 1);
error = hammer_lock_upgrade(&cursor->node->lock, 1);
error = hammer_lock_upgrade(&cursor->node->lock, 1);
error = hammer_lock_upgrade(&cursor->parent->lock, 1);
error = hammer_lock_upgrade(&cursor->node->lock, 1);
error = hammer_lock_upgrade(&nodes[i]->lock, counts[i]);