How to cCheck Size of a share/folder?

Hephaestus wrote:
I am not certain why it was possible to do it for full volume, yet it is supposedly so difficult to have similar indicators next to each share/folder. This is pretty basic functionality - and is still sadly missing.

It's simple for the entire volume because the file system does know how many data blocks are used in total. Without the quota feature I mentioned above, btrfs doesn't have an easy way to track how many data blocks are uniquely used in each folder when snapshots are enabled.

Some of the other proposed features (in particular using --reflink by default when moving files between shares) make this problem more complicated, since it extends CoW across share boundaries. That is, moving a file that way will result in the data blocks being shared between the new share, the new share's snapshots and the old share's snapshots.

I also want the feature (along with some better tools to manage snapshots generally). But there are cases where such indicators will be confusing - for instance when CoW is extended across shares, the sum of the space used in each share won't add up to the total space used in the volume.