[RESOLVED] Failed to start Remount Root and Kernel File Systems

[gnomek]

I moved my btrfs system to a larger disk. When I start it, it loads and works ok but I see this Failure information. I don't know where is the cause of the problem.

systemctl status systemd-remount-fs.service
× systemd-remount-fs.service - Remount Root and Kernel File Systems
Loaded: loaded (/usr/lib/systemd/system/systemd-remount-fs.service; enabled-runtime; preset: disabled)
Active: failed (Result: exit-code) since Mon 2023-06-19 09:36:44 CEST; 2min 28s ago
Docs: man:systemd-remount-fs.service(
https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
Process: 201 ExecStart=/usr/lib/systemd/systemd-remount-fs (code=exited, status=1/FAILURE)
Main PID: 201 (code=exited, status=1/FAILURE)
CPU: 120ms

cze 19 09:36:44 user_name systemd-remount-fs[203]: mount: /: mount point is not moounted or not proper option was given.
cze 19 09:36:44 user_name systemd-remount-fs[203]: dmesg(1) can give more information m>
cze 19 09:36:44 user_name systemd-remount-fs[201]: /usr/bin/mount for / exited with exit status 32.
cze 19 09:36:44 user_name systemd[1]: systemd-remount-fs.service: Main process exited, code=exited, status=1/FAILURE
cze 19 09:36:44 user_name systemd[1]: systemd-remount-fs.service: Failed with result 'exit-code'.
cze 19 09:36:44 user_name systemd[1]: Failed to start Remount Root and Kernel File Systems.
Notice: journal has been rotated since unit was started, output may be incomplete.

Edition:
dmesg shows:

BTRFS error (device sda1: state M): cannot disable free space tree

I found a solution here
Replacing

space_cache

to

space_cache=v2

in

/etc/fstab

works.

[jlittle]

Thank you. Which OS and kernel?

I ask because I've removed space_cache from fstab in all my installs that use btrfs. I've found that space_cache=v2 is applied by default, for a while now (the thread you linked says since kernel 5.15). I wonder:

• does it depends on the particular fs instance
• what would result if space_cache was removed

[claydoh]

I might test this later. On Neon (22.04), calamares sets space_cache in the fstab, and you can't boot after installing. You need to edit the installer config beforehand, or edit the fstab afterward, to set it to v2.

[Snowhog]

On Neon (22.04), calamares sets space_cache in the fstab, and you can't boot after installing.

Hmm. That wasn't the case in my Neon 22.04 installation. My fstab has:

# <file system> <mount point> <type> <options> <dump> <pass>
UUID=d092e4dc-9c2d-471a-8908-eb720fe92a8f / btrfs subvol=/@,defaults,noatime,space_cache,autodefrag 0 0
UUID=d092e4dc-9c2d-471a-8908-eb720fe92a8f /home btrfs subvol=/@home,defaults,noatime,space_cache,autodefrag 0 0

And I didn't edit after the installation. Everything works fine.

[claydoh]

Hmm. That wasn't the case in my Neon 22.04 installation. My fstab has:

I believe they may have fixed the image (after my pestering them maybe 😃). and/or it reverted back, They build isos weekly. Or some Ubuntu update fixed things, perhaps.
My own recent-ish experience as well as other recent, instances

[gnomek]

Which OS and kernel?

This is on Manjaro, kernel 6.3.5-2.

[Snowhog]

This is on Manjaro

Just a little bit peeved. We are not a Manjaro Linux support forum. Just say’n.

[gnomek]

Sorry, I thought it was more about btrfs than distribution related problem, but I will keep that it mind.