inc_children
void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
inc_children(info->tm, result->n, vt);
inc_children(info->tm, dm_block_data(*result), vt);
inc_children(info->tm, node, vt);
int *inc_children)
r = dm_sm_count_is_more_than_one(tm->sm, orig, inc_children);
if (is_shadow(tm, orig) && !*inc_children)
struct dm_block **result, int *inc_children);