copy_file_range support

[TPolzer]

Would it be possible to support copy_file_range? That could potentially speed up file copies enormously for filesystems that are copy on write or remote.

https://libfuse.github.io/doxygen/structfuse__operations.html#a8dab2194663f561ef7db54de2ca35694

[tv42]

FUSE_COPY_FILE_RANGE was added in protocol 7.28, we're currently stuck around 7.12 because last I looked, OSXFUSE didn't support 7.20 (https://github.com/osxfuse/osxfuse/issues/155) and then both the OSXFUSE upstream and Apple turned hostile to open source (https://github.com/bazil/fuse/issues/224).

This will likely get done after dropping macOS support. Which is pretty much going to bring out the mobs with torches, but no maintainers...

[paralin]

Since MacOS support was dropped, could this be added?

[tv42]

Need to check what FreeBSD is up to, but yes, we should be able to bring the protocol up now a lot more easily than writing lots of conditionals and alternate versions of types.