Re: [PATCH v2 01/12] fs-verity: add a documentation file

From: Theodore Y. Ts'o
Date: Fri Dec 21 2018 - 11:28:34 EST

On Fri, Dec 21, 2018 at 07:53:54AM -0800, Matthew Wilcox wrote:
> In contrast to "we'll just fix it up later" (which usually applies
> to in-kernel interfaces), we have a policy of not breaking userspace,
> so accepting this interface means setting it in stone. We should get
> it right.

I'm not convinced it's a "fix", but my point is that if later on you
want to add extra complexity transforming


so it does the equivalent of

fd, sizeof_data, sizeof_verity_data);

it adds essentially no complexity to provide this backwards
compatibility. But if we need to implement
nothing, other than pushing back when fsverity lands upstream. We'd
have to provide that backwards compatibility interface anyway, since
there are a lot of users for that existing interface.

So why?

- Ted