Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20211028094724.59043-1-lmb@cloudflare.com> <20211028094724.59043-3-lmb@cloudflare.com>
In-Reply-To: <20211028094724.59043-3-lmb@cloudflare.com>
From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Tue, 2 Nov 2021 10:25:10 +0100
Message-ID: <CAJfpegvPrQBnYO3XNcCHODBBCXm6uH73zOWXs+sfn=3LQmMyww@mail.gmail.com>
Subject: Re: [PATCH bpf-next v3 2/4] libfs: support RENAME_EXCHANGE in simple_rename()
To:     Lorenz Bauer <lmb@cloudflare.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Miklos Szeredi <mszeredi@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        network dev <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, 28 Oct 2021 at 11:48, Lorenz Bauer <lmb@cloudflare.com> wrote:
>
> Allow atomic exchange via RENAME_EXCHANGE when using simple_rename.
> This affects binderfs, ramfs, hubetlbfs and bpffs.

Ramfs and hugetlbfs are generic enough; those seem safe.

Binderfs: I have no idea what this does; binderfs_rename() should
probably error out on RENAME_EXCHANGE for now, or an explicit ack from
the maintainers.

Bpffs is your baby...

Thanks,
Miklos