hammer_lock_ex_ident
void hammer_lock_ex_ident(struct hammer_lock *lock, const char *ident);
hammer_lock_ex_ident(lock, "hmrlck");
hammer_lock_ex_ident(&cursor->deadlk_node->lock, "hmrdlk");
hammer_lock_ex_ident(&cursor->deadlk_node->lock, "hmrdlk");