Bug#959228: grub2: Grub2 V2.04-7 does not recognize BTRFS RAID1c4 filesystem

[waxhead]

Source: grub2
Version: 2.04-7
Severity: important

Dear Maintainer,

*** Reporter, please consider answering these questions, where appropriate ***

   * What led up to the situation?

    I waited for grub 2.04-7 to support the BTRFS RAID1c3/RAID1c4 features.
    it found that it had migraded to testing this morning, did an apt update + apt upgrade to get it.
    Made sure I ran update-grub, and btrfs balance start -mconvert=raid1c4 /
    also checked with apt-get source grub2 , browsed the btrfs.c to check , all the raid1c34 parts
    seemed to be in place.
    ran systemd reboot and grub failed with unknown filesystem.

   * What exactly did you do (or not do) that was effective (or
     ineffective)?

   Fired up the latest testing live cd and rebalanced my rootfs back to btrfs raid1

   * What was the outcome of this action?

   Grub2 apparently does not support RAID1c34 even if it should (cherry picked from upstream)
   I was able to recover, therefore only a temporarily data "loss" until I rebalanced my rootfs.

   * What outcome did you expect instead?

   That Grub2 should support the RAID1c3/4 feature in BTRFS as this is available in Debian now.

*** End of the template - remove these template lines ***


-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.5.0-2-amd64 (SMP w/2 CPU cores)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled