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

On Thu, Apr 16, 2026 at 05:03:26PM +0200, Jori Koolstra wrote:
> 
> > Op 16-04-2026 16:21 CEST schreef Dorjoy Chowdhury <[email protected]>:
> > 
> >  
> > On Thu, Apr 16, 2026 at 7:52 PM Jori Koolstra <[email protected]> wrote:
> > >
> > > On Sat, Mar 28, 2026 at 11:22:22PM +0600, Dorjoy Chowdhury wrote:
> > > > diff --git a/arch/alpha/include/uapi/asm/fcntl.h b/arch/alpha/include/uapi/asm/fcntl.h
> > > > index 50bdc8e8a271..fe488bf7c18e 100644
> > > > --- a/arch/alpha/include/uapi/asm/fcntl.h
> > > > +++ b/arch/alpha/include/uapi/asm/fcntl.h
> > > > @@ -34,6 +34,7 @@
> > > >
> > > >  #define O_PATH               040000000
> > > >  #define __O_TMPFILE  0100000000
> > > > +#define OPENAT2_REGULAR      0200000000
> > > >
> > >
> > > I don't quite understand why we are adding OPENAT2_REGULAR inside the
> > > O_* flag range. Wasn't this supposed to be only supported for openat2()?
> > > If so, I don't see the need to waste an O_* flag bit. But maybe I am
> > > missing something.
> > >
> > 
> > Yes, OPENAT2_REGULAR is only supported for openat2. I am not sure if I
> > got a specific review to not add OPENAT2_REGULAR in the O_* flag 32
> > bit range. But as far as I understand, for the old open system calls
> > we can't easily add new O_* flags as the older codepaths don't strip
> > off unknown bits which openat2 does. It's not easy to add new O_*
> > flags for the old open system calls since that could break userspace
> > programs.
> 
> If I recall correctly, Aleksa has suggested we might also want to add
> O_EMPTYPATH to openat() instead of only allowing this for openat2().
> I am waiting to see what Christian thinks of this.

We can do that, yes. For O_EMPTYPATH that is workable.

I don't mind too much if we leave OPENAT2_REGUALR in the 32-bit flag
space. It'll silently be ignored but the flag name should give it away.