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[104.178.186.189]) by smtp.gmail.com with ESMTPSA id w20-20020a05620a0e9400b006b5b1d632bbsm848434qkm.99.2022.07.12.16.10.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Jul 2022 16:10:26 -0700 (PDT) Date: Tue, 12 Jul 2022 19:10:18 -0400 From: Taylor Blau To: git@vger.kernel.org Cc: gitster@pobox.com, derrickstolee@github.com, peff@peff.net, ps@pks.im, wfc@wfchandler.org Subject: [PATCH 0/3] commit-graph: fix corruption during generation v2 upgrade Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org This brief series resolves a bug where a commit-graph would become corrupt when upgrading from generation number v1 to v2, as originally reported in [1]. Some speculation occurred as to what might be causing that bug in the thread beginning at [1], until the problem was explained in more detail by Will Chandler in [2]. The crux of the issue, as is described in [2] and [3], is that the commit_graph_data slab is reused for read and write operations involving the commit-graph, leading to situations where data computed in preparation of a write is clobbered by a read of existing data. The first patch demonstrates the issue, and the second patch prepares to fix it by introducing a helper function. The crux of the issue is described and fixed in the third patch. [1]: https://lore.kernel.org/git/YqD5dgalb9EPnz85@coredump.intra.peff.net/ [2]: https://lore.kernel.org/git/DD88D523-0ECA-4474-9AA5-1D4A431E532A@wfchandler.org/ [3]: https://lore.kernel.org/git/YsS7H4i5DqUZVQ5i@nand.local/ Taylor Blau (3): t5318: demonstrate commit-graph generation v2 corruption commit-graph: introduce `repo_find_commit_pos_in_graph()` commit-graph: fix corrupt upgrade from generation v1 to v2 bloom.c | 10 +++++----- commit-graph.c | 12 +++++++++--- commit-graph.h | 15 +++++++++++++++ t/t5318-commit-graph.sh | 27 +++++++++++++++++++++++++++ 4 files changed, 56 insertions(+), 8 deletions(-) -- 2.37.0.1.g1379af2e9d