fstrim.service no longer trims /home partition

[Jeffery To]

When I was running disco, fstrim.service would trim all of my partitions:

Oct 21 00:00:18 computer systemd[1]: Starting Discard unused blocks on filesystems from /etc/fstab...
Oct 21 00:00:37 computer fstrim[9588]: /home: 25 GiB (26797150208 bytes) trimmed on /dev/mapper/ubuntu--vg-home
Oct 21 00:00:37 computer fstrim[9588]: /boot: 805.4 MiB (844546048 bytes) trimmed on /dev/sda5
Oct 21 00:00:37 computer fstrim[9588]: /: 5.5 GiB (5929816064 bytes) trimmed on /dev/mapper/ubuntu--vg-root
Oct 21 00:00:37 computer systemd[1]: fstrim.service: Succeeded.
Oct 21 00:00:37 computer systemd[1]: Started Discard unused blocks on filesystems from /etc/fstab.

After upgrading to eoan, my /home partition is no longer trimmed:

Oct 28 00:00:21 computer systemd[1]: Starting Discard unused blocks on filesystems from /etc/fstab...
Oct 28 00:00:32 computer fstrim[24667]: /boot: 781.1 MiB (819011584 bytes) trimmed on /dev/sda5
Oct 28 00:00:32 computer fstrim[24667]: /: 7.2 GiB (7696994304 bytes) trimmed on /dev/mapper/ubuntu--vg-root
Oct 28 00:00:32 computer systemd[1]: fstrim.service: Succeeded.
Oct 28 00:00:32 computer systemd[1]: Started Discard unused blocks on filesystems from /etc/fstab.

Checking the unit file (/lib/systemd/system/fstrim.service), I noticed there is a "ProtectHome=yes" option. Removing this option caused my /home partition to be trimmed once again.

I believe the "ProtectSystem=strict" option may also cause partitions in non-standard partition schemes to be skipped by fstrim.service (although I have not tested this).

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Matt Vickers (mattyv)]

I can confirm this bug. Viewing systemd logs on my system showed the weekly TRIM of /home stopped around the end of October 2019 as reported by Jeffery.

This bug was filed upstream (https://github.com/karelzak/util-linux/issues/824) and will affect users with /home on a separate partition.

It was patched with the following one-line commit c64d452b3eb85fe55e238144082247b05cc143ea:
-ProtectHome=yes
+ProtectHome=read-only

[Jeffery To (jefferyto)]

Thanks Matt. Looks like the fix will be in the next upstream release (2.35).

[Jeffery To (jefferyto)]

At this moment, this issue is still present in focal. It would be nice if this can be fixed for an LTS release.

[Jeffery To (jefferyto)]

groovy has been released with 2.36 so I will mark this issue as fixed.