samba network folder sizing for folders on btrfs-raid

btrfs-dfree.py

#!/usr/bin/env python3
# based on omv-btrfs-dfree from openmediavault
import os
import re
import subprocess
import sys
from systemd import journal

CUSTOMRATIO = 0 # set ratio of your btrfs volume if samba user is not root (smb.conf: force user = root)
LOGGING = 0 # 0 - off, 1 - on. journalctl -t 'SMBUS'

def main():
    path = os.path.realpath(sys.argv[1] if len(sys.argv) > 0 else '.')

    output = subprocess.run(
        ['btrfs', 'filesystem', 'usage', '--raw', '-T', path],
        capture_output=True
    ).stdout.decode()

    re_matches_for_total = r'.+Device size:\s+(\d+)\n.+'
    matches_for_total = re.match(
        re_matches_for_total,
        output, re.DOTALL
    )
    if os.getuid() == 0: # if samba user is root we can get ratio to calculate total space
        re_matches_for_ratio = r'.+Data ratio:\s+(\d+\.\d+).+'
        matches_for_ratio = re.match(
            re_matches_for_ratio,
            output, re.DOTALL
        )
        ratio = float(matches_for_ratio.group(1))
    else: # else set ratio = 1 but can get wrong total size
        if CUSTOMRATIO == 0:
            ratio = 1
        else:
            ratio = CUSTOMRATIO

    if os.getuid() == 0: # if user is root we can get estimated (minimum) free space
        re_matches_for_available = r'.+Free \(estimated\):\s+\d+\s+\(min: (\d+)\)\n.+'
    else: # otherwise only 'statfs' free
        re_matches_for_available = r'.+Free \(statfs, df\):\s+(\d+)\n.+'
    matches_for_available = re.match(
        re_matches_for_available,
        output, re.DOTALL
    )

    if matches_for_total is not None:
        totalb = matches_for_total.group(1)
        availableb = matches_for_available.group(1)
        if LOGGING == 1:
            journal.stream('SMBUS').write(f'SMB VARS: userid={os.getuid()}, ratio={ratio}, availableb={availableb}, totalb={totalb}')
            for line in output.splitlines():
                journal.stream('SMBUS').write(f'{line}')
        total =     round(int(totalb) // (1024 * ratio))
        available = round(int(availableb) // 1024)

    else:
        output = subprocess.run(
            ['df', '--portability', '--print-type', '--block-size=1K', path],
            capture_output=True
        ).stdout.decode()
        _, _, total, _, available, *_ = output.split('\n')[1].split()
    sys.stdout.write(f'{total} {available} 1024\n')



if __name__ == "__main__":
    sys.exit(main())

smb.conf

[Public]
    ....
    dfree command = /etc/samba/btrfs-dfree.py
    dfree cache time = 60
    # optionally. Otherwise set btrfs volume ratio manually via CUSTOMRATIO variable in python script
    force user = root
    force group = root
    ....