copy_file_range already works on zfs, but it doesn't guarantee anything interesting. Basically all dupe tools that are modern use fideduprange, which is meant

copy_file_range already works on zfs, but it doesn't guarantee anything interesting. Basically all dupe tools that are modern use fideduprange, which is meant to tell the FS which things should be sharing data, and let it take care of the rest. (BTRFS, bcachefs, etc support this ioctl, and zfs will soon too) Unlike copy_file_range, it is meant for exactly this use case, and will tell you how many bytes were dedup'd, etc.