Then, what does a package maintainer rely on?

Edit: I’m so dumb. It’s obvious they’d check original developer’s repo or issue tracker. I’m sorry

You are right. I shouldn’t have used diff. I’ll fix that

Also, incremental changes from subvolume to its snapshot might be incorrect as that will be new data added to subvolume, rather that old data deleted from subvolume while still present in snapshot. I’ll have to check carefully.

just comparing the subvolume with its snapshot with btrfs send -p /example/subvol /snapshot/of/example/subvol >examplediff.btrfs.

From man btrfs-send

generate a stream of instructions that describe changes between two subvolume snapshots

Thanks for btdu, it seems useful as ‘btrfs fi du’ probably doesn’t account for compression, will check it out sometime.

Thanks that helped. I have one snapshot of home. Size of diff between btrfs subvolume and Additional space used by snapshot is 11GiB (probably) and btrfs fi du -s / is 72GiB, making 83GiB (closer to btrfs fi df /).

Between btrfs filesystem usage / and btrfs filesystem du -s / there’s nearly 11GiB difference for used space. I have checked btrfs du -hs <path/to/subvolume> for all subvolume in the filesystem, and total seems to be 72 GiB, hence the confusion. Still I don’t know if I’m using the tools properly or something else is at fault here.

To correct myself, 11GiB is additional space used by snapshot probably used space difference between btrfs fi usage and btrfs fi du -s / is because of diff between snapshot and parent volume (didn’t consider that while adding all used GiB of subvolumes). So btrfs filesystem usage works well to check used/free space.

edit: fix incorrect args; additional space is not diff

user’s password can be totally different from luks password if you’re using autologin. You can keep it same but that’s totally optional. You can login without entering any password at all if not using luks (or using autodecrypt), you can see that in live isos.