Re: [PATCH v6 1/4] openat2: new OPENAT2_REGULAR flag support

[Christian Brauner <brauner@kernel.org>]

On Mon, Apr 27, 2026 at 08:17:43PM +0600, Dorjoy Chowdhury wrote:
> On Mon, Apr 27, 2026 at 7:28 PM Florian Weimer <fweimer@redhat.com> wrote:
> >
> > * Dorjoy Chowdhury:
> >
> > > diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/errno.h
> > > index 92e7ae493ee3..bd78e69e0a43 100644
> > > --- a/include/uapi/asm-generic/errno.h
> > > +++ b/include/uapi/asm-generic/errno.h
> > > @@ -122,4 +122,6 @@
> > >
> > >  #define EHWPOISON    133     /* Memory page has hardware error */
> > >
> > > +#define EFTYPE               134     /* Wrong file type for the intended operation */
> > > +
> > >  #endif
> >
> > This is what POSIX says about EFTYPE, in the Rationale for System
> > Interfaces:
> >
> > “
> > [EFTYPE]
> >     This error code was proposed in earlier proposals as "Inappropriate
> >     operation for file type", meaning that the operation requested is
> >     not appropriate for the file specified in the function call. This
> >     code was proposed, although the same idea was covered by [ENOTTY],
> >     because the connotations of the name would be misleading. It was
> >     pointed out that the fcntl() function uses the error code [EINVAL]
> >     for this notion, and hence all instances of [EFTYPE] were changed to
> >     this code.
> > ”
> >
> > So I'm not sure if reusing this name is a good idea.
> >
> 
> Thanks for pointing this out. I had started out the patch series with
> ENOTREGULAR and it was discussed that EFTYPE was a better and more
> generic error code which is also used in BSD systems like FreeBSD[1]
> and MacOS[2]. I also agree that EFTYPE makes sense. We can of course
> change to something else if everyone agrees.
> 
> cc Christian Brauner who originally suggested EFTYPE for input on this.
> 
> [1]: https://man.freebsd.org/cgi/man.cgi?errno(2)
> [2]: https://developer.apple.com/documentation/foundation/posixerror/eftype

Given that both the bsds and macos already use that is there a good
reason to return ENOTTY for this other than a standard we ignore most of
the time anyway? I'm honestly asking.