BTRFS volume mount fails at boot, but works once system is up

[danieljrmay]

Hi @chrismurphy

@chrismurphy

If no or you don’t remember you can just sudo dracut -f and it will be regenerated based on the current configuration; and now you can lsinitrd the new initramfs and grep for btrfs to see if it’s now included (or not).

Yes just for the record if I do:

$ sudo uname -a
Linux oxygen 5.8.13-200.fc32.x86_64 #1 SMP Thu Oct 1 21:49:42 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

$ sudo lsinitrd /boot/initramfs-5.8.13-200.fc32.x86_64.img | grep btrfs
$ # No mentions of btrfs found

$ sudo dracut -f

$ sudo lsinitrd /boot/initramfs-5.8.13-200.fc32.x86_64.img | grep btrfs
$ # No mentions of btrfs found

So it might be something that dracut should be doing but isn’t. Anyway hopefully we are getting this to the right people.

Thank you ever so much for all your help with this.

Cheers, Dan

[chrismurphy]

Yep. In the meantime, I suspect it’s possible to use a drop-in dracut configuration file to add the udev rule. Or use the x-systemd.automount mount option in fstab.

[danieljrmay]

Hi @chrismurphy,

Yes I seem to have got it working now by doing this:

$ sudo dracut --add btrfs --force

$ sudo lsinitrd /boot/initramfs-5.8.13-200.fc32.x86_64.img | grep btrfs
Arguments: --add 'btrfs' --force
btrfs
-rw-r--r--   1 root     root           20 May 29 19:35 etc/cmdline.d/00-btrfs.conf
-rw-r--r--   1 root     root          616 May 29 19:35 usr/lib/udev/rules.d/64-btrfs.rules
-rwxr-xr-x   1 root     root       965424 May 29 19:35 usr/sbin/btrfs
lrwxrwxrwx   1 root     root            5 May 29 19:35 usr/sbin/btrfsck -> btrfs

So now the BTRFS volume mounts automatically at boot and I can’t seem to make it fail to even when my disks are in funny configurations, split between HBA and direct motherboard connections.

Presumably I will have to do this dracut --add btrfs --force everytime there is a new kernel until dracut is modified to add the minimal btrfs stuff when there is any btrfs filesystem in /etc/fstab not just the root filesystem. Or is the fact that I’ve added the btrfs module once carried forward even though fedora is using dracut --hostonly by default? I guess I will find out!

I have been looking at man dracut and it looks like I can prompt dracut to add the btrfs module by modifying /etc/dracut.conf or creating /etc/dracut.conf.d/myconf.conf. I haven’t done that yet because I want to understand it all a bit better first.

I’m sure the x-systemd.automount option in /etc/fstab would work too.

The other solution coming around the corner is to do a clean install of Fedora 33 and have it’s default btrfs root filesystem solve the problem for me too.

[blueshurricane4 (Tim Cuthbertson)]

@danieljrmay

I have been looking at man dracut and it looks like I can prompt dracut to add the btrfs module by modifying /etc/dracut.conf or creating /etc/dracut.conf.d/myconf.conf . I haven’t done that yet because I want to understand it all a bit better first.

Yes, that is all you need to do. It will have the same effect as “–add btrfs” every time dracut is run.