Re: [PATCH] repack: do not rebuild packs on --dry-run
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Oct 8, 2026, 14:23 UTC
- Message-ID
- <xmqqwlrs2rvc.fsf@gitster.g>
- In-Reply-To
- <20261008062521.25505-1-r.siddharth.shrimali@gmail.com>
Siddharth Shrimali <r.siddharth.shrimali@gmail.com> writes:
Show 10 quoted lines
> "git repack --drop-filtered --dry-run" is documented to list the > objects that would be dropped "without rebuilding any pack or > deleting anything", but it does both. > > This is a bug in cmd_repack(): after printing the candidates, the > --dry-run block falls through into the regular repack code. > repack_promisor_objects() writes a new promisor pack, and with -d, > existing_packs_remove_redundant() deletes the old packs. The command > still exits successfully, so the user is not told that the repository > was modified.
Very interesting finding. I am curious if this was the case from the beginning, or we broke --dry-run unknowingly as a side effect of some unrelated changes. If it is not too much, can you bisect and document where we broke it in the log message?
Show 65 quoted lines
> The existing guard only skips the implied "delete_redundant = 1", so
> it does not stop an explicit -d, nor the new pack from being written.
>
> Fix it by returning right after the candidates are listed, and add a
> test that checks the pack directory is unchanged with and without -d.
>
> Reported-by: Coy Geek <coygeek@gmail.com>
> Signed-off-by: Siddharth Shrimali <r.siddharth.shrimali@gmail.com>
> ---
> Bug report:
> https://lore.kernel.org/git/CACgTecOm+=vbf50tZNXhcYvRi1ZTsQwbjVoJAbQqs2CmXdJCxg@mail.gmail.com/
>
> builtin/repack.c | 8 ++++++++
> t/t7706-repack-drop-filtered.sh | 19 +++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/builtin/repack.c b/builtin/repack.c
> index c4360382c1..c048053912 100644
> --- a/builtin/repack.c
> +++ b/builtin/repack.c
> @@ -391,6 +391,14 @@ int cmd_repack(int argc,
> oidset_iter_init(&drop_oids, &iter);
> while ((oid = oidset_iter_next(&iter)))
> printf("%s\n", oid_to_hex(oid));
> +
> + /*
> + * add an exit here, so that dry run does not
> + * go on to rebuild any pack or delete anything, even
> + * if the user explicitly asked for -d
> + */
> + ret = 0;
> + goto cleanup;
> }
> }
>
> diff --git a/t/t7706-repack-drop-filtered.sh b/t/t7706-repack-drop-filtered.sh
> index cb36115834..a1c475e4ec 100755
> --- a/t/t7706-repack-drop-filtered.sh
> +++ b/t/t7706-repack-drop-filtered.sh
> @@ -135,6 +135,25 @@ test_expect_success '--dry-run does not remove the filtered objects' '
> git -C repo cat-file -e "$BIG"
> '
>
> +test_expect_success '--dry-run leaves the pack directory untouched' '
> + BIG=$(cat big_oid) &&
> + packdir=repo/.git/objects/pack &&
> +
> + for opt in "" -d
> + do
> + ls $packdir >before &&
> +
> + git -C repo -c repack.writeBitmaps=false \
> + repack --drop-filtered --filter=blob:limit=1k \
> + --dry-run -a $opt >out &&
> +
> + ls $packdir >after &&
> + test_cmp before after &&
> + test_grep "$BIG" out &&
> + git -C repo cat-file -e "$BIG" || return 1
> + done
> +'
> +
> test_expect_success '--drop-filtered removes the promisor blob locally' '
> BIG=$(cat big_oid) &&
> SMALL=$(cat small_oid) &&