Request: subvolume qgroup stats

[daviessm]

I have a script which lists all subvolumes for a filesystem and saves their usage referenced and exclusive values to a database for further analysis. Currently this calls btrfs subvolume show from btrfs-progs for each subvolume. It would be nice if I could use python-btrfs for this instead.

Ideally there would be an easy way to retrieve all the information provided by btrfs subvolume show.

[knorrie]

Hi! Yes, the qgroup related metadata objects are part of the collection (which is getting smaller \o/) of items that have not been implemented yet.

So, after getting scrub in a workable state, this seems to be the next thing we're going to have a look at.

What you already can do now to help is:

• Start writing some program using python-btrfs that can do whatever the library already allows. So, basically, the end result you want, but without the qgroup information yet.
• Have a look at the btrfs-progs code, to see in which way it's retrieving the qgroup data that you want to see. In the end, in the python code, you probably will have to do a similar thing. Iterate over subvolumes (tree root numbers), and then execute some other metadata search operation to get the relevant qgroup info for each of them.

Knorrie