Systemd fails to mount btrfs multidevice filesystems in stage 2

[viric]

First, this only affects btrfs fs to be mounted by systemd, thus, stage 2.

As current nixos master, only one block device can be told to be waited for.

In a usual btrfs approach, when all the block devices are ready, "btrfs dev scan" has to be run with the btrfs module loaded, and it will settle down the multidevice information.

I tried to get nixos supporting multiple devices in fileSystems, and having "btrfs dev scan" run as a udev rule, but this doesn't work: https://github.com/viric/nixos/compare/master...systemd_btrfs

Currently, my mount point (mnt-hd.mount) fails to mount this way:

   Loaded: loaded (/nix/store/jjq9jaaq3dgdafqvhmg8cmvcqa452z9c-unit/mnt-hd.mount)
   Active: failed (Result: exit-code) since dc 2013-04-17 00:01:14 CEST; 25min ago
    Where: /mnt/hd
     What: /dev/mapper/seagate-lvol0
  Process: 1473 ExecMount=/nix/store/wbr4qkpf1y1f6hzxs7gp9a1imnypihq7-util-linux-2.22.2/bin/mount /dev/mapper/seagate-lvol0 /mnt/hd -t btrfs -o noatime,autodefrag (code=exited, status=32)

abr 17 00:01:14 nispro mount[1473]: mount: wrong fs type, bad option, bad superblock on /d...l0,
abr 17 00:01:14 nispro mount[1473]: missing codepage or helper program, or other error
abr 17 00:01:14 nispro mount[1473]: In some cases useful info is found in syslog - try
abr 17 00:01:14 nispro mount[1473]: dmesg | tail or so
abr 17 00:01:14 nispro systemd[1]: mnt-hd.mount mount process exited, code=exited status=32
abr 17 00:01:14 nispro systemd[1]: Failed to mount Mount of dev-mapper-seagate\x2dlvol0,d...ol0.
abr 17 00:01:14 nispro systemd[1]: Unit mnt-hd.mount entered failed state

I'm using this config, with my branch:

fileSystems = ...
    { mountPoint = "/mnt/hd";
      devices = [ "/dev/mapper/seagate-lvol0" "/dev/mapper/wdgreen-lvol0" ];
      options = "noatime,autodefrag";
      fsType = "btrfs";
      }

As an additional comment, systemd udev seems to have some magic about btrfs that I don't understand: http://lists.freedesktop.org/archives/systemd-commits/2012-September/002503.html

[vcunat]

From the first look it seems to me that the udev "magic" is connected to multi-device btrfs filesystems.

My btrfs /home partition mounts fine (it's in stage2, isn't it?), but I only have systemd-200 and it's one-device only.

[viric]

On Tue, Apr 23, 2013 at 12:50:42PM -0700, Vladimír Čunát wrote:

From the first look it seems to me that the udev "magic" is connected to multi-device btrfs filesystems.

Yes, to me too, but as something doesn't work for me, I'm a bit lost.

My btrfs /home partition mounts fine (it's in stage2, isn't it?), but I only have systemd-200.

I tried that in 199, 200 and 201, to no difference. Is your /home partition multi-device, and over LVM?

[vcunat]

No, just regular one-device (I added this info straight after posting the previous comment, but you only read the e-mail).

[viric]

Ok, I think it's definitely a multidevice trouble :)

[domenkozar]

Is this still an issue?