[[!comment format=mdwn
 username="joey"
 subject="""comment 8"""
 date="2017-04-05T15:26:59Z"
 content="""
git-annex does use CoW in a few situations; it does so by running `cp
--reflink` and letting it use CoW features when available. However,
I don't see where `git annex add` would use that, and of course I don't see
why that feature would break for you even if it did run cp that way.

git also uses CoW, at least it uses `mmap` with `MAP_PRIVATE`. I'm not
clear if/how that involves the filesystem layer.

This remains puzzling, but knowing it's limited to btrfs on Arch Linux
with CoW is certianly a good start.

It seems like a bug in btrfs would not be out of the question.
Trying some different kernel versions might be useful.

It would perhaps be useful to get `strace -ff` logs.
"""]]