[Help][Bug] Git pull fails while pulling large commits on FUSE based filesystem

[Help][Bug] Git pull fails while pulling large commits on FUSE based filesystem

[Palaniappan Nagarajan]

Hi Community,
We have a peculiar environment: We use git repository on a directory
mounted using s3-fuse(https://github.com/s3fs-fuse/s3fs-fuse). The
directory is backed up to the Amazon S3 bucket. Whenever we try to run
`git pull` that could pull in *large commits*, we are facing the
following error.

$ git pull origin main
remote: Enumerating objects: 102, done.
remote: Counting objects: 100% (102/102), done.
remote: Compressing objects: 100% (101/101), done.
remote: Total 102 (delta 1), reused 102 (delta 1), pack-reused 0
Receiving objects: 100% (102/102), 72.24 MiB | 15.48 MiB/s, done.
Resolving deltas: 100% (1/1), completed with 1 local object.
fatal: Failed to checksum '.git/objects/pack/tmp_pack_VvTvzo': No such
file or directory
fatal: fetch-pack: invalid index-pack output

I can confirm that the file '.git/objects/pack/tmp_pack_XXXXX' is
present once the command completes. In the S3 fuse logs, I see that
the file is read before the file is created.

The issue happens only during `git pull` and `git clone` with the
large commits works without any issues.

Can anyone help with any pointers/ workaround/ potential solution to
fix this issue? Is there a way to override the location of temporary
files "tmp_pack_XXXXX" files so that it can be created outside the
mount directory? Setting the object directory outside the mount
directory using GIT_OBJECT_DIRECTORY is not an option as we want to
backup git history.

P.S. My experiment that could throw some light on the issue.
1. Created a Git repository with 1000 files of 1 MB.
(https://github.com/cyn0/2kfiles-large)
2. Git clone on the mounted directory works without any issue.
3. Added 5 files of each 1MB size to the repository.
(https://github.com/cyn0/2kfiles-large/commit/42aa5d83e9035460ffa9c3b2f4494c0828f6b1c7)
4. From the mounted directory, "git pull origin main" works without any size.
5. Now, add 100 files of each 1MB to the repository.
(https://github.com/cyn0/2kfiles-large/commit/7304886116d9bdec8a8c2da020776995a6624bd2)
6. From the mounted directory, "git pull origin main" fails with the
above error.

Thanks in advance for your help!

Regards,
Palaniappan