[PATCH 5/5] fs: Convert struct file::f_count to refcount_long_t

[Kees Cook]

On Fri, May 03, 2024 at 01:14:45AM +0100, Al Viro wrote:
> On Thu, May 02, 2024 at 05:10:18PM -0700, Kees Cook wrote:
> 
> > But anyway, there needs to be a general "oops I hit 0"-aware form of
> > get_file(), and it seems like it should just be get_file() itself...
> 
> ... which brings back the question of what's the sane damage mitigation
> for that.  Adding arseloads of never-exercised failure exits is generally
> a bad idea - it's asking for bitrot and making the thing harder to review
> in future.

Linus seems to prefer best-effort error recovery to sprinkling BUG()s
around.  But if that's really the solution, then how about get_file()
switching to to use inc_not_zero and BUG on 0?

-- 
Kees Cook