Re: repository corruption when pushing commits to a repository running 'git gc --prune='

Matthieu Moy [off-list ref] writes:

This looks like a race between deleting objects/05/ and creating
objects/05/cdb51bb0ea3e229734a4b1bddd5ec70fbc65ed.

I don't understand how this is possible, since the temporary file and
the final one are in the same directory, so deleting the directory
should fail.

What am I missing?

 1. tmp_obj_* gets created in objects/05/ by "git unpack-objects";

 2. prune_cruft() comes, notices tmp_obj_* that is sufficiently old,
    decides to remove in "git prune".

 3. prune_subdir() comes, notices objects/05/ is now empty, does
    rmdir().

 4. "git unpack-objects" closes the file whose inode was originally
    associated with the path objects/05/tmp_obj_*;

 5. "git unpack-objects" calls finalize_object_file() and tries to
    link(2) or rename(2) it to its final name.  It does not find the
    source of the link or rename and says "oops, no such file".