Hello!

> Alexey seems to disagree with this approach, is it possible to elaborate
> a little bit ?

My first reaction was exactly the same as David's one. Exactly. :-)

flowi structure was invented to be both easily initialized/disposed
as a local variable and copied/stored in various caches as a key.

If it has some reference inside, it becomes really ugly.

But it is the first reaction. I guess you do not have much of choice.
The only alternative is to add an additional argument to functions
taking flowi, which is even uglier.

So, it looks like netns still have to go to flowi, but functions copying
flowi (in route.c/flow.c/whatever) should not use raw memcpy to store this
and must remember that saving flowi is possible only when refcnt to netns
is held somewhere.

Alexey