Copy btrfs

[aslak47]

I added handling of btrfs. I have tested both full copying to new disk as well as refreshening old copies.
I added a force option (-f) when changing contents of existing partition to new btrfs filesystem (from ext4).
You will find interesting information on setting labels for different filesystems here. e2label is primarily for ext2/3/4 filesystem.

[framps]

Looks pretty good 👍

I added a force option (-f) when changing contents of existing partition to new btrfs filesystem (from ext4).

I don't see any force option code added in your PR. Do I miss something?

[aslak47]

See line # 1607 in my version of the script file

[framps]

I saw this addition but I expected you add another invocation option for rpi-clone. So I misunderstood your comment. Would you please explain the usage scenario of when changing contents of existing partition to new btrfs filesystem (from ext4) to better understand your comment?

[aslak47]

I actually copied from a disk containing the btrfs in a partisjon to another disk where the corresponding partisjon contaned a ext4 filesystem. That forced creating a btrfs to replace the ext4 filesystem and a full copy of contents.

[framps]

Thank you. I got it now. That's a nice feature but for me a clone should be identical to the source which is not true if the ext4 filesystem is changed to btrfs under the cover. Other than that the PR LGTM.

@geerlingguy What's your opinion on this? We may add a new option which enables this under the cover FS conversation. But frankly I think that's overkill. So I think we either accept this under the cover conversation or the PR should be updated so it fails if the clone doesn't have a btrfs filesystem already.