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

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Date: Wed, 26 Jun 2024 15:39:47 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: Xi Ruoyao <xry111@...111.site>
Cc: brauner@...nel.org, 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 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.

> --
> Xi Ruoyao <xry111@...111.site>
> School of Aerospace Science and Technology, Xidian University



-- 
Mateusz Guzik <mjguzik gmail.com>