Re: [PATCH v2] fs: try an opportunistic lookup for O_CREAT opens too

[Al Viro]

On Wed, Aug 14, 2024 at 03:18:17AM +0100, Al Viro wrote:

> That's not the only problem; your "is it negative" test is inherently
> racy in RCU mode.  IOW, what is positive at the time you get here can
> bloody well go negative immediately afterwards.  Hit that with
> O_CREAT and you've got a bogus ENOENT...

Hmm...  OTOH, in that case you end up in step_into(), which will do the
right thing...

	How well does that series survive NFS client regression tests?
That's where I'd expect potentially subtle shite, what with short-circuited
->d_revalidate() on the final pathwalk step in open()...