[PATCH v2 2/2] commit-graph: propagate topo_levels slab to all chain layers

["Kristofer Karlsson via GitGitGadget" <gitgitgadget@gmail.com>]

From: Kristofer Karlsson <krka@spotify.com>

The topo_levels slab is only propagated to the topmost graph
layer instead of all layers in the chain.  Commits from lower
layers appear to have no generation numbers, so the DFS
re-walks the entire ancestry.

Fix by making topo_levels visible to all layers, not just
the first one.

Signed-off-by: Kristofer Karlsson <krka@spotify.com>
---
 commit-graph.c                | 2 +-
 t/t5324-split-commit-graph.sh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/commit-graph.c b/commit-graph.c
index 702ba9731b..a0bca248ac 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -2610,7 +2610,7 @@ int write_commit_graph(struct odb_source *source,
 
 	g = prepare_commit_graph(ctx.r);
 	for (struct commit_graph *chain = g; chain; chain = chain->base_graph)
-		g->topo_levels = &topo_levels;
+		chain->topo_levels = &topo_levels;
 
 	if (flags & COMMIT_GRAPH_WRITE_BLOOM_FILTERS)
 		ctx.changed_paths = 1;
diff --git a/t/t5324-split-commit-graph.sh b/t/t5324-split-commit-graph.sh
index b41331e3dd..9e5ab7dbd0 100755
--- a/t/t5324-split-commit-graph.sh
+++ b/t/t5324-split-commit-graph.sh
@@ -718,7 +718,7 @@ test_expect_success 'write generation data chunk when commit-graph chain is repl
 	)
 '
 
-test_expect_failure 'incremental write reads topo levels from all layers' '
+test_expect_success 'incremental write reads topo levels from all layers' '
 	git init topo-from-lower &&
 	(
 		cd topo-from-lower &&
-- 
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