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From: Lorenz Bauer <lmb@cloudflare.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: kernel-team@cloudflare.com, Lorenz Bauer <lmb@cloudflare.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH bpf-next 0/2] Support RENAME_EXCHANGE on bpffs
Date: Wed, 20 Oct 2021 09:29:54 +0100	[thread overview]
Message-ID: <20211020082956.8359-1-lmb@cloudflare.com> (raw)

Add support for renameat2(RENAME_EXCHANGE) on bpffs. This is useful
for atomic upgrades of our sk_lookup control plane.

* Create a temporary directory on bpffs
* Migrate maps and pin them into temporary directory
* Load new sk_lookup BPF, attach it and pin the link into temp dir
* renameat2(temp dir, state dir, RENAME_EXCHANGE)
* rmdir temp dir

Due to the sk_lookup semantics this means we can never end up in a
situation where an upgrade breaks the existing control plane.

Lorenz Bauer (2):
  libfs: support RENAME_EXCHANGE in simple_rename()
  selftests: bpf: test RENAME_EXCHANGE and RENAME_NOREPLACE on bpffs

 fs/libfs.c                                    |  6 ++-
 .../selftests/bpf/prog_tests/test_bpffs.c     | 39 +++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

-- 
2.30.2


             reply	other threads:[~2021-10-20  8:30 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-20  8:29 Lorenz Bauer [this message]
2021-10-20  8:29 ` [PATCH bpf-next 1/2] libfs: support RENAME_EXCHANGE in simple_rename() Lorenz Bauer
2021-10-20  8:29 ` [PATCH bpf-next 2/2] selftests: bpf: test RENAME_EXCHANGE and RENAME_NOREPLACE on bpffs Lorenz Bauer
2021-10-20 21:43   ` Andrii Nakryiko
2021-10-21  0:14 ` [PATCH bpf-next 0/2] Support RENAME_EXCHANGE " Alexei Starovoitov

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