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

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Message-ID: <CAGudoHFrTWktBYQjrQMJbVZvWLPD3A51YsOMOJqAtpdruSkGsQ@mail.gmail.com>
Date: Wed, 25 Sep 2024 17:56:40 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: Xi Ruoyao <xry111@...111.site>
Cc: brauner@...nel.org, Miao Wang <shankerwangmiao@...il.com>, 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, Sep 25, 2024 at 4:30 PM Xi Ruoyao <xry111@...111.site> wrote:
> There's a special case, AT_FDCWD + NULL + AT_EMPTY_PATH, still resulting
> EFAULT, while AT_FDCWD + "" + AT_EMPTY_PATH is OK (returning the stat of
> current directory).
>
> I know allowing NULL with AT_FDCWD won't produce any performance gain,
> but it seems the difference would make the document of the API more
> nasty.
>
> So is it acceptable to make the kernel "hide" this difference, i.e.
> accept AT_FDCWD + NULL + AT_EMPTY_PATH as-is AT_FDCWD + "" +
> AT_EMPTY_PATH?
>

huh, that indeed makes sense to add. kind of weird this was not sorted
out at the time, but i'm not going to pointer a finger at myself :) so
ACK from me as far as the idea goes

I presume you can do the honors? :)

-- 
Mateusz Guzik <mjguzik gmail.com>