linux-kernel - Re: [PATCH v3] vfs: support statx(..., NULL, AT_EMPTY

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Date: Wed, 26 Jun 2024 16:35:45 +0200
From: Christian Brauner <brauner@...nel.org>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: Xi Ruoyao <xry111@...111.site>, viro@...iv.linux.org.uk, jack@...e.cz, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, io-uring@...r.kernel.org, 
	axboe@...nel.dk, torvalds@...ux-foundation.org, loongarch@...ts.linux.dev
Subject: Re: [PATCH v3] vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)

On Wed, Jun 26, 2024 at 03:39:47PM GMT, Mateusz Guzik wrote:
> On Wed, Jun 26, 2024 at 4:59 AM Xi Ruoyao <xry111@...111.site> wrote:
> >
> > On Tue, 2024-06-25 at 17:18 +0200, Mateusz Guzik wrote:
> > > +     if ((sx->flags & (AT_EMPTY_PATH | AT_STATX_SYNC_TYPE)) ==
> > > +         (AT_EMPTY_PATH | AT_STATX_SYNC_TYPE) &&
> > > +         vfs_empty_path(sx->dfd, path)) {
> > >               sx->filename = NULL;
> > > -             return ret;
> >
> > AT_STATX_SYNC_TYPE == AT_STATX_FORCE_SYNC | AT_STATX_DONT_SYNC but
> > AT_STATX_FORCE_SYNC and AT_STATX_DONT_SYNC obviously contradicts with
> > each other.  Thus valid uses of statx won't satisfy this condition.
> >
> 
> I don't know wtf I was thinking, this is indeed bogus.
> 
> > And I guess the condition here should be same as the condition in
> > SYSCALL_DEFINE5(statx) or am I wrong?
> >
> 
> That I disagree with. The AUTOMOUNT thing is a glibc-local problem for
> fstatat. Unless if you mean the if should be of similar sort modulo
> the flag. :)
> 
> I am going to fix this up and write a io_uring testcase, then submit a
> v4. Maybe today or tomorrow.

Fwiw, I had already dropped the io_uring bits when I pushed to
#vfs.mount. So just put that as a separate patch on top.