From: Taylor Blau <me@ttaylorr.com>
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
Date: Tue, 12 Jul 2022 19:10:18 -0400 [thread overview]
Message-ID: <cover.1657667404.git.me@ttaylorr.com> (raw)
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
next reply other threads:[~2022-07-12 23:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-12 23:10 Taylor Blau [this message]
2022-07-12 23:10 ` [PATCH 1/3] t5318: demonstrate commit-graph generation v2 corruption Taylor Blau
2022-07-15 3:15 ` Derrick Stolee
2022-07-15 22:05 ` Taylor Blau
2022-07-16 0:01 ` Junio C Hamano
2022-07-16 0:17 ` Taylor Blau
2022-07-12 23:10 ` [PATCH 2/3] commit-graph: introduce `repo_find_commit_pos_in_graph()` Taylor Blau
2022-07-15 3:17 ` Derrick Stolee
2022-07-12 23:10 ` [PATCH 3/3] commit-graph: fix corrupt upgrade from generation v1 to v2 Taylor Blau
2022-07-13 17:41 ` [PATCH 0/3] commit-graph: fix corruption during generation v2 upgrade Junio C Hamano
2022-07-15 2:02 ` Taylor Blau
2022-07-15 3:20 ` Derrick Stolee
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