Bug#958236: grub2: rootfs may be rendered unbootable due to grub2 not supporting the latest btrfs features

[waxhead]

Source: grub2
Version: 2.04-5
Severity: grave
Tags: patch
Justification: causes non-serious data loss

Dear Maintainer,

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

   * What led up to the situation?

   The latest kernel (5.5) and btrfs-progs 5.6 supports rebalancing to a new metadata mode for the filfeystem caller Raid1c3 or Raid1c4.
   unlike the regular raid1 this allows for more copies of the data.
   If your rootfs is btrfs , and you rebalance either metadata or data to raid1c3/raid1c4 your system is not unbootable.

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

   I downloaded the grub2 source with apt-get source grub2 , and checked grub-core/fs/btrfs.c for the additions found here:
   https://git.savannah.gnu.org/cgit/grub.git/commit/?id=495781f5ed1b48bf27f16c53940d6700c181c74c
   They are missing and hence your rootfs can become unbootable.

   * What was the outcome of this action?

   I could not find that this patch was applied
   https://git.savannah.gnu.org/cgit/grub.git/commit/?id=495781f5ed1b48bf27f16c53940d6700c181c74c

   * What outcome did you expect instead?
   I would expect grub2 to include this minor patch to support btrfs raid1c3/raid1c4


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

Kernel: Linux 5.5.0-1-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