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From: Junio C Hamano <gitster@pobox.com>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, stolee@gmail.com
Subject: Re: [PATCH v3 2/9] midx.c: make changing the preferred pack safe
Date: Fri, 14 Jan 2022 13:43:55 -0800	[thread overview]
Message-ID: <xmqqsftq9en8.fsf@gitster.g> (raw)
In-Reply-To: <xmqqwnj29f1v.fsf@gitster.g> (Junio C. Hamano's message of "Fri, 14 Jan 2022 13:35:08 -0800")

Junio C Hamano <gitster@pobox.com> writes:

> Taylor Blau <me@ttaylorr.com> writes:
>
>> ... It's likely we were using
>> finalize_object_file() instead of a pure rename() because the former
>> also adjusts shared permissions.
>
> I thought the primary reason why we use finalize was because we
> ignore EEXIST (and the assumption is that the files with the same
> contents get the same name computed from their contents).
>
>>  	tmp_file = write_rev_file_order(NULL, ctx->pack_order, ctx->entries_nr,
>>  					midx_hash, WRITE_REV);
>>  
>> -	if (finalize_object_file(tmp_file, buf.buf))
>> +	if (rename(tmp_file, buf.buf))
>>  		die(_("cannot store reverse index file"));
>
> Doesn't your new code die with it if buf.buf names an existing file?

Ah, scratch that.  rename() discards the old one atomically, so as
long as tmp_file and buf.buf are in the same directory (which I
think it is in this case), we wouldn't be affected by the bug that
is worked around with "Coda hack" in finalize_object_file(), either.


  reply	other threads:[~2022-01-14 21:44 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-08 19:26 [PATCH 0/2] midx: prevent bitmap corruption when permuting pack order Taylor Blau
2021-12-08 19:26 ` [PATCH 1/2] t5326: demonstrate bitmap corruption after permutation Taylor Blau
2021-12-08 19:26 ` [PATCH 2/2] midx.c: make changing the preferred pack safe Taylor Blau
2021-12-08 19:30 ` [PATCH 0/2] midx: prevent bitmap corruption when permuting pack order Derrick Stolee
2021-12-08 19:55   ` Jeff King
2021-12-10 18:36     ` Taylor Blau
2021-12-10 22:31       ` Taylor Blau
2021-12-11  1:39         ` Taylor Blau
2021-12-13 14:00           ` Derrick Stolee
2021-12-13 14:31             ` Taylor Blau
2021-12-14  1:55 ` [PATCH v2 0/8] " Taylor Blau
2021-12-14  1:55   ` [PATCH v2 1/8] t5326: demonstrate bitmap corruption after permutation Taylor Blau
2021-12-14  1:55   ` [PATCH v2 2/8] midx.c: make changing the preferred pack safe Taylor Blau
2021-12-14  1:55   ` [PATCH v2 3/8] pack-revindex.c: instrument loading on-disk reverse index Taylor Blau
2021-12-14  1:55   ` [PATCH v2 4/8] t5326: drop unnecessary setup Taylor Blau
2021-12-14  1:55   ` [PATCH v2 5/8] t5326: extract `test_rev_exists` Taylor Blau
2021-12-20 18:33     ` Derrick Stolee
2022-01-04 15:33       ` Taylor Blau
2021-12-14  1:55   ` [PATCH v2 6/8] t5326: move tests to t/lib-bitmap.sh Taylor Blau
2021-12-14  1:55   ` [PATCH v2 7/8] t/lib-bitmap.sh: parameterize tests over reverse index source Taylor Blau
2021-12-14  1:55   ` [PATCH v2 8/8] midx: read `RIDX` chunk when present Taylor Blau
2021-12-20 18:42     ` Derrick Stolee
2022-01-04 15:21       ` Taylor Blau
2021-12-15 19:46   ` [PATCH v2 0/8] midx: prevent bitmap corruption when permuting pack order Junio C Hamano
2021-12-15 21:37     ` Taylor Blau
2021-12-15 22:17       ` Junio C Hamano
2021-12-15 22:55         ` Junio C Hamano
2021-12-20 18:51     ` Derrick Stolee
2021-12-20 19:52       ` Taylor Blau
2021-12-20 20:09         ` Derrick Stolee
2021-12-15 22:58   ` Junio C Hamano
2021-12-15 23:01     ` Taylor Blau
2022-01-04 18:15 ` [PATCH v3 0/9] " Taylor Blau
2022-01-04 18:15   ` [PATCH v3 1/9] t5326: demonstrate bitmap corruption after permutation Taylor Blau
2022-01-20 17:55     ` Jonathan Tan
2022-01-20 22:11       ` Taylor Blau
2022-01-20 22:41         ` Junio C Hamano
2022-01-20 22:46           ` Taylor Blau
2022-01-24 17:40         ` Jonathan Tan
2022-01-04 18:15   ` [PATCH v3 2/9] midx.c: make changing the preferred pack safe Taylor Blau
2022-01-14 21:35     ` Junio C Hamano
2022-01-14 21:43       ` Junio C Hamano [this message]
2022-01-15  0:59         ` Taylor Blau
2022-01-15  6:27           ` Junio C Hamano
2022-01-20 18:08     ` Jonathan Tan
2022-01-20 22:13       ` Taylor Blau
2022-01-04 18:15   ` [PATCH v3 3/9] pack-revindex.c: instrument loading on-disk reverse index Taylor Blau
2022-01-20 18:15     ` Jonathan Tan
2022-01-20 22:18       ` Taylor Blau
2022-01-24 17:53         ` Jonathan Tan
2022-01-04 18:15   ` [PATCH v3 4/9] t5326: drop unnecessary setup Taylor Blau
2022-01-04 18:15   ` [PATCH v3 5/9] t5326: extract `test_rev_exists` Taylor Blau
2022-01-04 18:15   ` [PATCH v3 6/9] t5326: move tests to t/lib-bitmap.sh Taylor Blau
2022-01-04 18:15   ` [PATCH v3 7/9] t/lib-bitmap.sh: parameterize tests over reverse index source Taylor Blau
2022-01-24 19:15     ` Jonathan Tan
2022-01-25 21:40       ` Taylor Blau
2022-01-26 21:00         ` Jonathan Tan
2022-01-04 18:16   ` [PATCH v3 8/9] midx: read `RIDX` chunk when present Taylor Blau
2022-01-24 19:27     ` Jonathan Tan
2022-01-25 21:45       ` Taylor Blau
2022-01-26 21:28         ` Jonathan Tan
2022-01-04 18:16   ` [PATCH v3 9/9] pack-bitmap.c: gracefully fallback after opening pack/MIDX Taylor Blau
2022-01-24 19:29     ` Jonathan Tan
2022-01-25 21:46       ` Taylor Blau
2022-01-25 22:40 ` [PATCH v4 0/9] midx: prevent bitmap corruption when permuting pack order Taylor Blau
2022-01-25 22:41   ` [PATCH v4 1/9] t5326: demonstrate bitmap corruption after permutation Taylor Blau
2022-01-26 15:01     ` Ævar Arnfjörð Bjarmason
2022-01-26 20:18       ` Taylor Blau
2022-01-25 22:41   ` [PATCH v4 2/9] midx.c: make changing the preferred pack safe Taylor Blau
2022-01-25 22:41   ` [PATCH v4 3/9] pack-revindex.c: instrument loading on-disk reverse index Taylor Blau
2022-01-26 15:03     ` Ævar Arnfjörð Bjarmason
2022-01-25 22:41   ` [PATCH v4 4/9] t5326: drop unnecessary setup Taylor Blau
2022-01-25 22:41   ` [PATCH v4 5/9] t5326: extract `test_rev_exists` Taylor Blau
2022-01-26 15:04     ` Ævar Arnfjörð Bjarmason
2022-01-26 20:19       ` Taylor Blau
2022-01-25 22:41   ` [PATCH v4 6/9] t5326: move tests to t/lib-bitmap.sh Taylor Blau
2022-01-25 22:41   ` [PATCH v4 7/9] t/lib-bitmap.sh: parameterize tests over reverse index source Taylor Blau
2022-01-25 22:41   ` [PATCH v4 8/9] midx: read `RIDX` chunk when present Taylor Blau
2022-01-26 15:10     ` Ævar Arnfjörð Bjarmason
2022-01-26 20:23       ` Taylor Blau
2022-01-25 22:41   ` [PATCH v4 9/9] pack-bitmap.c: gracefully fallback after opening pack/MIDX Taylor Blau
2022-01-26 15:08     ` Ævar Arnfjörð Bjarmason
2022-01-26 17:50   ` [PATCH v4 0/9] midx: prevent bitmap corruption when permuting pack order Ævar Arnfjörð Bjarmason
2022-01-26 20:24     ` Taylor Blau
2022-01-27 17:15       ` Jonathan Tan
2022-02-24 22:50         ` Taylor Blau
2022-01-27 14:13   ` Derrick Stolee

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