JGit is unable to discover bitmaps on filesystem

[lucamilanesio]

Version

All releases from v4.10.* onwards

Operating System

Linux/Unix

Bug description

Context

Bare repos can be at time transferred at the filesystem level (with the target location in read-only until the transfer is complete) across Gerrit servers.

I am running on defaults for JGit and Gerrit.

Example:

• Server-1 (read-only) has repo1.git bare repository
• Server-2 (read-only) receives repo1.git via rsync and stay in read-only until the transfer is complete

I do not see anything wrong with the above approach, as long as Server-2 is read-only until the transfer is complete.

Steps to reproduce the problem

1. Rsync repo1.git repo with the exception of the bitmap
2. run a git clone against Server-2 / repo1.git using Git/SSH
3. Observe on the Server-2 in the sshd_log that the bitmap is not used
4. Complete the rsync of repo1.git, which will transfer the bitmap
5. run a git clone against Server-2 / repo1.git using Git/SSH

Actual behavior

At point 5. the sshd_log shows that the bitmap is not used. After a full restart of Gerrit, the action 5. reports that the bitmap is used in the sshd_log.

Expected behavior

At point 5. the sshd_log shows that the bitmap is used

Relevant log output

See the log of the sshd_log execution on a Gerrit v3.5.6 (JGit 6.6.0 @74fa245b3c3ccf13afcbec7911c7c8459e48527d)

At point 2. clone without bitmap:

[2024-01-12T10:32:32.491Z] 33cc307a [SSH git-upload-pack /repo1 (admin)] admin a/1000000 git-upload-pack./repo1 5ms 55ms '0ms 27ms 0ms 8ms 0ms 4ms 39ms -1 141 440 37967' 0 - 47ms 40ms 1493344

At point 5. clone with bitmap:

[2024-01-12T10:39:22.108Z] 53bd24d6 [SSH git-upload-pack /repo1 (admin)] admin a/1000000 git-upload-pack./repo1 6ms 54ms '0ms 28ms 0ms 7ms 0ms 4ms 39ms -1 141 440 37967' 0 - 42ms 30ms 1474304

After a Gerrit restart, at point 5. clone with bitmap:

[2024-01-12T10:40:37.388Z] a5799f52 [SSH git-upload-pack /repo1 (admin)] admin a/1000000 git-upload-pack./repo1 4ms 60ms '0ms 39ms 0ms 1ms 0ms 5ms 45ms 0 141 440 37971' 0 - 54ms 40ms 895768

Other information

See Change 1174396

[msohn]

The change was merged as 3e62430