Question about disallowing rename(2) in cgroup v2

["taoyi.ty" <escape@xxxxxxxxxxxxxxxxx>]

hi all,

I found that rename(2) can be used in cgroup v1 but is disallowed in 
cgroup v2, what's the reason for this design?

rename(2) is critical when managing a cgroup pool in userspace, which 
uses rename to reuse cgroup rather than mkdir to create a new one，this 
can improve the performance of container concurrent startup, because 
renaming cgroup is much more lightweight compared with creating cgroup.

For new features in cgroup v2, I switch to cgroup v2 and meet this 
problem, I think renaming cgroup in v2 is similar to v1 and realizing it 
is not a hard problem, so I send this mail to learn the initial design.

Thanks,
-escape