[PATCH v2 0/2] object-file: fix packfile flush during transaction commit

[Justin Tobler <jltobler@gmail.com>]

Greetings,

This short series fixes a bug I found related to committing an ODB
transaction that contains both a loose object and "large" blob when also
configured to batch fsync loose objects. The issue can be reproduced
with the following:

        git init
        git config core.fsync loose-object
        git config core.fsyncMethod batch
        git config core.bigFileThreshold 5
        echo foo >1-foo && echo foobar >2-foobar
        git add 1-foo 2-foobar

and produces the following error:

        error: unable to write file .git/objects/pack/pack-2b7c2470289822070687e8d64186093a710eaed3.pack: No such file or directory
        fatal: unable to rename temporary file to '.git/objects/pack/pack-2b7c2470289822070687e8d64186093a710eaed3.pack'

If a "large" blob packfile is written to the transaction temporary
directory, it is unable to be flushed during transaction commit because
the underlying transaction is migrated to the main ODB before the
packfile is finalized. To avoid this, this series ensures any pending
packfile in the transaction is flushed first.

Changes since V1:
- Updated a commit message of first patch.
- Improved test readability in second patch.

Thanks,
-Justin

Justin Tobler (2):
  object-file: lift ODB reprepare out of packfile flush
  object-file: flush transaction packfile before migrating objects

 object-file.c    | 12 ++++++++----
 t/t1050-large.sh | 17 +++++++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

Range-diff against v1:
1:  cf14416f22 ! 1:  6f74391ae8 object-file: lift ODB reprepare out of packfile flush
    @@ Commit message
     
         When flushing a packfile via `flush_packfile_transaction()`,
         `odb_reprepare()` is invoked so the written packfile becomes visible in
    -    the current process. In a subsequent commit, repreparing the ODB is
    -    slightly deferred when committing a "files" ODB transaction.
    +    the current process. In a subsequent commit, flushing the packfile is
    +    performed earlier when committing a "files" ODB transaction, but the ODB
    +    reprepare needs to remain the last step.
     
         Lift ODB reprepare out of `flush_packfile_transaction()` and instead
         require callers to explicitly invoke `odb_reprepare()` if required.
2:  18a1798d95 ! 2:  ad2fa8ee3f object-file: flush transaction packfile before migrating objects
    @@ t/t1050-large.sh: test_expect_success 'add a large file or two' '
     +test_expect_success 'add large file with loose object in batch fsync' '
     +	test_when_finished "rm -rf batch" &&
     +	git init batch &&
    ++	(
    ++		cd batch &&
    ++		git config core.bigFileThreshold 5 &&
    ++		echo foo >1-small &&
    ++		echo foobar >2-large &&
     +
    -+	git -C batch config core.bigFileThreshold 5 &&
    -+	echo foo >batch/1-small &&
    -+	echo foobar >batch/2-large &&
    ++		git -c core.fsync=loose-object -c core.fsyncMethod=batch \
    ++			add 1-small 2-large &&
     +
    -+	git -C batch -c core.fsync=loose-object -c core.fsyncMethod=batch \
    -+		add 1-small 2-large &&
    -+
    -+	# Neither object may be left behind in a temporary location.
    -+	git -C batch cat-file -e :1-small &&
    -+	git -C batch cat-file -e :2-large
    ++		git cat-file -e :1-small &&
    ++		git cat-file -e :2-large
    ++	)
     +'
     +
      test_expect_success 'checkout a large file' '

base-commit: 47ce80527c56f462cb97db4ca8125342204d3783
-- 
2.55.0.424.g13c7afec21