如何理解这个句子结构It's a relief to know that life eventually gave Ch

定语从句（Attributive Clauses）在句中做定语,修饰一个名词或代词,被修饰的名词,词组或代词即先行词.
你认定它不是定语从句,说明你不明白哪个是它的先行词,此处的先行词就是happiness；用的是过去分词的完成时态作后置定语 .
如：I cannot forget the event took place yesterday .此句中took place yesterday 即是 event的后置定语 ,省略了which/that ,在口语中是可以的,正式语体就该是I cannot forget the event that/which took place yesterday.
例句的原句是
it's a relief to know that life eventually gave Chaplin the stable happiness which it had earlier denied him .生活并没有一开始给卓别林幸福但最终给了他完美幸福 ,知道了这个是一种宽尉.

个人认为，it had earlier denied him与前边在语法上没有任何联系，怀疑是印刷错误，应为It had earlier denied him我是这样理解的。

it代表后面句子的意思，
原句应该是to know that life eventually gave Chaplin the stable happiness is arelief
it had earlier denied him这个句子是用来限定happiness的，是happiness的定语