[Bug 1830110] Update Released

Timo Aaltonen 1830110 at bugs.launchpad.net
Tue Apr 29 08:09:55 UTC 2025


The verification of the Stable Release Update for cryptsetup has
completed successfully and the package is now being released to
-updates.  Subsequently, the Ubuntu Stable Release Updates Team is being
unsubscribed and will not receive messages about this bug report.  In
the event that you encounter a regression using the package from
-updates please report a new bug using ubuntu-bug and tag the bug report
regression-update so we can easily find any regressions.

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https://bugs.launchpad.net/bugs/1830110

Title:
  patch for finding zfs, solves:  cryptsetup: WARNING: Couldn't
  determine root device

Status in cryptsetup package in Ubuntu:
  Fix Released
Status in cryptsetup source package in Focal:
  Fix Released
Status in cryptsetup package in Debian:
  New

Bug description:
  [ Impact ]
  When updating the initramfs, error messages will be displayed:
  cryptsetup: ERROR: Couldn't resolve device rpool/ROOT/ubuntu_fvdajm
  cryptsetup: WARNING: Couldn't determine root device

  This is due to ZFS not having MAJ/MIN device numbers, which causes issues with
  cryptsetup detecting the root FS.

  [ Test Plan ]
  The best way I've found to test this is to setup the LUKS devices from an
  existing Ubuntu installation (or e.g. the Desktop Live ISO), and debootstrap a
  focal system on it. This seems to replicate a new install very closely, and the
  issue can be trivially reproduced by updating the initramfs:

  root at ubuntu20.04:/# lsblk
  vda       252:0    0    25G  0 disk
  ├─vda1    252:1    0   512M  0 part  /boot/efi
  ├─vda2    252:2    0   500M  0 part
  ├─vda3    252:3    0     2G  0 part
  └─vda4    252:4    0    22G  0 part
    └─luks1 253:0    0    22G  0 crypt
  root at ubuntu20.04:/# zpool status -P rpool
    pool: rpool
   state: ONLINE
  status: ...
  action: ...
  config:

   NAME                 STATE     READ WRITE CKSUM
   rpool                ONLINE       0     0     0
    /dev/mapper/luks1  ONLINE       0     0     0

  root at ubuntu20.04:/# update-initramfs -u
  update-initramfs: Generating /boot/initrd.img-5.4.0-205-generic
  cryptsetup: ERROR: Couldn't resolve device rpool/ROOT/ubuntu_fvdajm
  cryptsetup: WARNING: Couldn't determine root device

  After backporting the ZFS patch for initramfs-tools/hooks/cryptroot from newer
  Ubuntu releases:
  root at ubuntu20.04:/# update-initramfs -u
  update-initramfs: Generating /boot/initrd.img-5.4.0-205-generic
  root at ubuntu20.04:/#

  In summary, the following scenarios should be covered by testing to ensure no regressions have been introduced:
  - ZFS on top of LUKS (manual setup according to the instructions above)
  - regular encrypted LUKS setup (i.e. LVM+luks from the installer)
  - regular ZFS (available as advanced option in the installer)

  [ Where Problems Could Occur ]
  Potential issues would likely show up during initramfs creation for systems that
  have LUKS devices, as that's where we have changes.
  We now return an empty device number for ZFS, and ignore devices that don't have
  a devno. This could cause issues with other filesystem types that also don't
  have device number information, and potentially expose other issues with
  LUKS-encrypted ZFS partitions.

  [ Other Information ]
  The fix has been cherry-picked from mwhudson's cryptsetup merge, to be aligned
  with other Ubuntu releases (specifically, commit 8a583307a038 [0]). Focal is the
  only release still missing this patch, so it's the only one we need to target.

  [0]
  https://git.launchpad.net/~mwhudson/ubuntu/+source/cryptsetup/commit/?id=8a583307a0386febc8d29c0c592d5d312b176e34

  --
  Hi there,

  There is a missing functionality in the following file:
  /usr/share/initramfs-tools/hooks/cryptroot

  resulting in the following error message:

  cryptsetup: ERROR: Couldn't resolve device <zfs-mountpoint>
  cryptsetup: WARNING: Couldn't determine root device

  under the following condition:

  update-initramfs -c -k all

  when:

  trying to resolve for encrypted zfs devices

  so here is a patch to solve it, based off

  Package: cryptsetup-initramfs
  Version: 2:2.1.0-1ubuntu1

  diff -Naur a/usr/share/initramfs-tools/hooks/cryptroot b/usr/share/initramfs-tools/hooks/cryptroot
  --- a/usr/share/initramfs-tools/hooks/cryptroot	2019-05-22 18:34:12.116097472 +0100
  +++ b/usr/share/initramfs-tools/hooks/cryptroot	2019-05-22 20:13:02.159138688 +0100
  @@ -72,19 +72,28 @@
               # take the last mountpoint if used several times (shadowed)
               unset -v devnos
               spec="$(printf '%b' "$spec")"
  -            resolve_device "$spec" || continue # resolve_device() already warns on error
               fstype="$(printf '%b' "$fstype")"
  -            if [ "$fstype" = "btrfs" ]; then
  -                # btrfs can span over multiple devices
  -                if uuid="$(device_uuid "$DEV")"; then
  -                    for dev in "/sys/fs/$fstype/$uuid/devices"/*/dev; do
  -                        devnos="${devnos:+$devnos }$(cat "$dev")"
  -                    done
  -                else
  -                    cryptsetup_message "ERROR: $spec: Couldn't determine UUID"
  +            if [ "$fstype" = "zfs" ]; then
  +                # zfs can span over multiple devices
  +                for dev in $(zpool status -L -P | grep -o "/dev/[^ ]*"); do
  +                    MAJ="$(printf "%d\n" 0x$(stat -L -c"%t" -- "$dev"))"
  +                    MIN="$(printf "%d\n" 0x$(stat -L -c"%T" -- "$dev"))"
  +                    devnos="${devnos:+$devnos }$MAJ:$MIN"
  +                done
  +            else
  +                resolve_device "$spec" || continue # resolve_device() already warns on error
  +                if [ "$fstype" = "btrfs" ]; then
  +                    # btrfs can span over multiple devices
  +                    if uuid="$(device_uuid "$DEV")"; then
  +                        for dev in "/sys/fs/$fstype/$uuid/devices"/*/dev; do
  +                            devnos="${devnos:+$devnos }$(cat "$dev")"
  +                        done
  +                    else
  +                        cryptsetup_message "ERROR: $spec: Couldn't determine UUID"
  +                    fi
  +                elif [ -n "$fstype" ]; then
  +                    devnos="$MAJ:$MIN"
                   fi
  -            elif [ -n "$fstype" ]; then
  -                devnos="$MAJ:$MIN"
               fi
           fi
       done </proc/mounts

  Which works, I have tested it. However by solving this error message,
  the script can now continue further. And it then prints out some new
  messages that should not be there either. Unfortunately I could not
  track down the source of those subsequent warnings!

  They say:

  # update-initramfs -c -k all
  update-initramfs: Generating /boot/initrd.img-5.0.0-15-generic
  cryptsetup: WARNING: crypt_rpool1: ignoring unknown option 'nofail'
  cryptsetup: WARNING: crypt_rpool1: ignoring unknown option
      'x-systemd.device-timeout'

  So clearly there is something which does not recognize the fstab
  mounting options of:

  'nofail'
  and
  'x-systemd.device-timeout'

  However those options are indeed valid, and were found to have a
  working effect. They were tested also. So the warning is something
  else, somewhere else. And I cannot grep it. Cannot google it. Nothing
  happening in strace. It is pretty mysterious, as to where it is come
  from. Mysterious messages!

  Anyhow please take the first patch if you can. Or use those lines to
  make your own version to improve as you please.

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