[PATCH 0/4] align the behavior when opening "packed-refs"

Hi All:

As discussed in [1], we need to use mmap mechanism to open large "packed_refs" file to save the memory usage. This patch mainly does the following things:

1: Fix an issue that we would report an error when the "packed-refs" file is empty, which does not align with the runtime behavior. 2-4: Extract some logic from the existing code and then use these created helper functions to let fsck code to use mmap necessarily

[1] https://lore.kernel.org/git/20250503133158.GA4450@coredump.intra.peff.net

Really thank Peff and Patrick to suggest me to do above change.

Thanks, Jialuo

shejialuo (4):
  packed-backend: skip checking consistency of empty packed-refs file
  packed-backend: extract snapshot allocation in `load_contents`
  packed-backend: extract munmap operation for `MMAP_TEMPORARY`
  packed-backend: use mmap when opening large "packed-refs" file

 refs/packed-backend.c    | 106 +++++++++++++++++++++++----------------
 t/t0602-reffiles-fsck.sh |  13 +++++
 2 files changed, 75 insertions(+), 44 deletions(-)