[PATCH v2 0/2] Prevent re-reading 4 GiB files on every status

Several people have noticed that Git continually re-reads and re-hashes files that are an exact multiple of 4 GiB every time the index is refreshed (for example, when "git status" is called). This is slow and expensive, especially with SHA-1 DC, and it also causes performance problems when these files are used with Git LFS (because the same issue occurs, just with Git LFS hashing the data instead of Git).

Jason Hatton sent a patch previously to fix this, but it lacked tests and didn't get picked up. I've adopted their patch, making some minor changes to the commit message and including some tests, and also including a suitable test helper to make the tests possible. All credit should be directed to Jason, and I'll accept all the responsibility for any problems.

I don't anticipate this being in any way controversial, so I'm not expecting a huge number of rerolls, but of course one or two might be necessary.

Jason Hatton (1):
  Prevent git from rehashing 4GiB files

brian m. carlson (1):
  t: add a test helper to truncate files

 Makefile                 |  1 +
 statinfo.c               | 20 ++++++++++++++++++--
 t/helper/test-tool.c     |  1 +
 t/helper/test-tool.h     |  1 +
 t/helper/test-truncate.c | 27 +++++++++++++++++++++++++++
 t/t7508-status.sh        | 16 ++++++++++++++++
 6 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 t/helper/test-truncate.c