[PATCH v2 5/8] repack: follow kept packs when omitting cruft from the MIDX
- From
Taylor Blau <ttaylorr@openai.com>
- Date
- Oct 1, 2026, 04:11 UTC
- Message-ID
- <51e20444dac1223f0e0485dc5799ed6d592f7614.1790827875.git.me@ttaylorr.com>
- In-Reply-To
- <cover.1790827875.git.me@ttaylorr.com>
When performing a geometric repack with 'repack.midxMustContainCruft' set to "false", Git uses '--stdin-packs=follow' to copy (once-cruft) objects needed for reachability closure out of cruft packs. .keep packs do not normally participate in that walk, though they *are* included in the resulting MIDX.
A .keep pack can contain a commit that reaches an object whose only copy is in a cruft pack. When there is no previous MIDX and the repack writes a new pack, neither `midx_has_unknown_packs()` nor the `!names.nr` fallback require that cruft pack to be included. If the kept commit (or a descendant of it) is selected for bitmap coverage, the bitmap writer fails because the MIDX does not contain all of its reachable objects.
Pass excluded kept packs to the follow walk, using '!' for packs outside the existing MIDX and '^' for packs already covered by it. This copies needed objects out of cruft without copying objects in the kept packs. It also avoids including all cruft merely because a concurrent push has installed a temporary '.keep' file.
With '--pack-kept-objects', packs with '.keep' files participate in the geometric repack, and thus may have their objects copied. Packs specified as kept via '--keep-pack' still exclude their objects, even when their packs fall below the geometric split.
Signed-off-by: Taylor Blau <ttaylorr@openai.com> --- builtin/repack.c | 31 ++++++++++++++++++++++++++--- repack-midx.c | 5 +++++ t/t7704-repack-cruft.sh | 43 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 76 insertions(+), 3 deletions(-)
diff --git a/builtin/repack.c b/builtin/repack.c index 88b05e96b5b..27d6668a4ab 100644 --- a/builtin/repack.c +++ b/builtin/repack.c @@ -476,9 +476,11 @@ int cmd_repack(int argc, show_progress = !po_args.quiet && isatty(2); strvec_push(&cmd.args, "--keep-true-parents"); - for (i = 0; i < keep_pack_list.nr; i++) - strvec_pushf(&cmd.args, "--keep-pack=%s", - keep_pack_list.items[i].string); + /* Geometric follow walks exclude these packs through stdin instead. */ + if (!(geometry.split_factor && !midx_must_contain_cruft)) + for (i = 0; i < keep_pack_list.nr; i++) + strvec_pushf(&cmd.args, "--keep-pack=%s", + keep_pack_list.items[i].string); strvec_push(&cmd.args, "--non-empty"); if (!geometry.split_factor) { /* @@ -593,6 +595,29 @@ int cmd_repack(int argc, fprintf(in, "%c%s\n", marker, basename); } + if (!midx_must_contain_cruft) { + struct strbuf buf = STRBUF_INIT; + + for_each_string_list_item(item, &existing.kept_packs) { + char marker = '^'; + + strbuf_reset(&buf); + strbuf_addf(&buf, "%s.pack", item->string); + + if (po_args.pack_kept_objects && + !string_list_has_string(&keep_pack_list, + buf.buf)) + continue; + + /* Exclusions override any inclusion above. */ + if (!string_list_has_string(&existing.midx_packs, + buf.buf)) + marker = '!'; + + fprintf(in, "%c%s\n", marker, buf.buf); + } + strbuf_release(&buf); + } fclose(in); } diff --git a/repack-midx.c b/repack-midx.c index 64c7f8d0f42..9f7786aaac5 100644 --- a/repack-midx.c +++ b/repack-midx.c @@ -197,6 +197,7 @@ static void midx_included_packs(struct string_list *include, } if (opts->midx_must_contain_cruft || + (!geometry->split_factor && existing->kept_packs.nr) || midx_has_unknown_packs(include, geometry, existing)) { /* * If there are one or more unknown pack(s) present (see @@ -209,6 +210,10 @@ static void midx_included_packs(struct string_list *include, * reachability closure if the MIDX is bitmapped and one * or more of the bitmap's selected commits reaches a * once-cruft object that was later made reachable. + * + * Kept packs may also depend on cruft objects, since + * they are included above without necessarily being + * traversed by a non-geometric repack. */ for_each_string_list_item(item, &existing->cruft_packs) { /* diff --git a/t/t7704-repack-cruft.sh b/t/t7704-repack-cruft.sh index f7f83e70ffe..bc6d6f588fa 100755 --- a/t/t7704-repack-cruft.sh +++ b/t/t7704-repack-cruft.sh @@ -798,6 +798,49 @@ test_expect_success 'incremental repack includes cruft for MIDX bitmaps' ' ) ' +test_expect_success 'geometric repack follows kept packs to cruft objects' ' + setup_cruft_exclude_tests kept-cruft && + ( + cd kept-cruft && + + # Put HEAD in a kept pack, while its parent is still in + # a cruft pack. + pack=$(echo "HEAD^..HEAD" | git pack-objects --revs $packdir/pack) && + git prune-packed && + GIT_TEST_MULTI_PACK_INDEX=0 \ + git repack -d --geometric=2 --write-midx --write-bitmap-index \ + --keep-pack=pack-$pack.pack && + + test-tool find-pack -c 1 HEAD && + test-tool read-midx --show-objects $objdir >midx && + cruft=$(ls $packdir/*.mtimes) && + test_grep ! "$(basename "$cruft" .mtimes).idx" midx + ) +' + +test_expect_success 'full repack retains cruft pack in MIDX for unreachable kept objects' ' + setup_cruft_exclude_tests unreachable-kept-cruft && + ( + cd unreachable-kept-cruft && + + pack=$(echo "HEAD^..HEAD" | git pack-objects --revs $packdir/pack) && + touch $packdir/pack-$pack.keep && + + # Make the kept commit unreachable so that the full + # repack leaves its parent in a cruft pack. + git reset --hard one && + git tag -d four && + git reflog expire --all --expire=all && + + GIT_TEST_MULTI_PACK_INDEX=0 \ + git repack -a --write-midx --write-bitmap-index && + + test-tool read-midx --show-objects $objdir >midx && + cruft=$(ls $packdir/*.mtimes) && + test_grep "$(basename "$cruft" .mtimes).idx" midx + ) +' + test_expect_success 'repack --write-midx includes cruft when instructed' ' setup_cruft_exclude_tests exclude-cruft-when-instructed && (
-- 2.56.0.8.ga42f775cbe2