Re: [PATCH] vfs: Add AT_EMPTY_PATH_NOCHECK as unchecked AT_EMPTY_PATH

On Sat, Jun 22, 2024 at 03:41:19PM GMT, Linus Torvalds wrote:

On Sat, 22 Jun 2024 at 14:25, Mateusz Guzik [off-list ref] wrote:

quoted

+cc Linus

Thanks.

quoted

To sum up the problem: stat and statx met with "" + AT_EMPTY_PATH have
more work to do than fstat and its hypotethical statx counterpart:
- buf alloc/free for the path
- userspace access (very painful on x86_64 + SMAP)
- lockref acquire/release

Yes. That LOOKUP_EMPTY_NOCHECK is *not* the fix.

I have explicitly NAKed an approach like this months ago in [1]. So I'm
not sure why we're getting that patch in the first place tbh.

[1]: https://lore.kernel.org/lkml/599df4a3-47a4-49be-9c81-8e21ea1f988a@xen0n.name (local)