[REQUEST] Correctly display ZFS available and used data

I have a few ZFS datasets which I like to monitor but btop currently has issues with correct display of used, available and total space of ZFS datasets.

In my setup I have a main dataset datengrab which also contains two child datasets datengrab/jan-data and datengrab/till-data. datengrab/till-data also has a storage quota of max. 500GB. The available storage space can be easily queried like this (*):

❯ zfs list -r datengrab
NAME                  USED  AVAIL  REFER  MOUNTPOINT
datengrab            1.56T  1.96T  1.18T  /mnt/datengrab
datengrab/jan-data   42.9G  1.96T  27.6G  /home/jan/jan-zfs-dataset
datengrab/till-data   318G   182G   300G  /home/tills/till-zfs-dataset

df also lists the available and used storage correctly:

❯ sudo df -h
Filesystem                              Size  Used Avail Use% Mounted on
[...]
datengrab                               3.2T  1.2T  2.0T  38% /mnt/datengrab
datengrab/jan-data                      2.0T   28G  2.0T   2% /home/jan/jan-zfs-dataset
datengrab/till-data                     483G  301G  182G  63% /home/tills/till-zfs-dataset

(Confusingly zfs USED and df Size report two very different things. For anyone interested there's a nice blog post on the topic: https://zedfs.com/all-you-have-to-know-about-reading-zfs-disk-usage/)

But now look at what btop reports:

These numbers are all over the place! Most obviously:

available storage for datengrab and datengrab/jan-data should be the same as they share the same pool
there seems to be some very strange rounding issues (total storage: 3.44TB != 3.49TB != 3.20TB)
datengrab/till-data should only display 182GB of available storage out of 500GB total because of the quota

I don't know how btop queries the disk usage under the hood but I hope this can be fixed somehow.

aristocratos / bpytop

[REQUEST] Correctly display ZFS available and used data #416