[linux-lvm] BLOCK_SIZE?

[Michael Tokarev <mjt tls msk ru>]

Little question that I already posted here a week ago or so.
What drawbacks can suffer if one changes BLOCK_SIZE in
include/linux/lvm.h from 1024 (or 4096 on S/390) to 512?
I can't understand from code what't a real purpose of
this constant, -- lvm seemed to work well with BLOCK_SIZE=512,
no troubles so far, -- but i'm still not shure if it is
"legal" to change that.  At least there is some purpose on
having different values for this constant on S/390 and other
platforms, -- again, can't see that purposes...

Oh yes, this is about 2.2 kernel and lvm-0.9.

Thank you.

Regards,
 Michael.