Calculate curvefs used storage capacity

[UniverseParticle]

Is your feature request related to a problem? (你需要的功能是否与某个问题有关?)

Describe the solution you'd like (描述你期望的解决方法)
Get the real value by statfs

Describe alternatives you've considered (描述你想到的折衷方案)

Additional context/screenshots (更多上下文/截图)

[wsehjk]

I'm interested in this issue, please assign me.