Re: [PATCH] iov_iter: optimise iter type checking

[Al Viro]

On Wed, Jan 27, 2021 at 04:28:38PM +0000, David Laight wrote:

> I'd definitely leave the type as a bitmap.

What the hell for?  Microoptimizations in places where we have
much heavier stuff to be done are bloody pointless.

It's already overcomplicated.  And compiler is _not_ going to
be able to prove that we'll only ever have one bit set, so
you would be making it harder to optimize, not to mention
reason about.