`Run0 btrfs scrub start` - No Stats Updated For Background Service

[vindicatorr]

btrfs: 6.17.1
kernel: 6.18.0-rc2
systemd: 259

When running a backgrounded scrub on a device using run0, the stats fail to update.
The associated file in /var/lib/btrfs/ is created or updated ONLY at the start of the scrub. No furthers updates are made.
The same holds true with btrfs scrub status.

This ONLY happens for the background use, and ONLY with run0.

A user in IRC confirmed they could reproduce the issue with run0 and stated it works as expected with sudo.

I'm guessing you're not going to enjoy this ride, because run0 (as I understand is just systemd-run) does other "funny" things: systemd/systemd#29714

Good:

$ run0 btrfs scrub start -B /<mountPath>
$ ls -l /var/lib/btrfs/
$ cat /var/lib/btrfs/<statsFile>
$ run0 btrfs scrub status /<mountPath>

(also "good", replacing run0 with sudo)

Bad:

$ run0 btrfs scrub start /<mountPath>
$ ls -l /var/lib/btrfs/
$ cat /var/lib/btrfs/<statsFile>
$ run0 btrfs scrub status /<mountPath>
<...>
no stats available
<...>

(stats file updates once at the start)