[Bug 1751517] Re: ubuntu bionic grub can't boot zstd compressed filesystem

[Dmitriy Geels]

Seems that btrfs ignores compression attribute if compression was set using mount option.
So, the solution is to set compression attributes per-directory:

1) remove 'compress=zstd' from your fstab root record
2) sudo btrfs property set /boot compression lzo # ensure this dir will remain readable by grub
3) sudo btrfs filesystem defragment -vrclzo /boot # ensure /boot gets recompressed
4) for $d in bin etc lib lib64 opt sbin snap srv usr var; do sudo btrfs property set /$d compression zstd; done

Directory list is for Ubuntu 18, check and adjust for your own needs.

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https://bugs.launchpad.net/bugs/1751517

Title:
  ubuntu bionic grub can't boot zstd compressed filesystem

Status in grub2 package in Ubuntu:
  Triaged
Status in grub2 package in Arch Linux:
  New

Bug description:
  In the /etc/fstab of installed ubuntu bionic system I specified compress=zstd for the btrfs root filesytem
  After runing 'sudo btrfs filesystem defragment -r -czstd /' the system booted to a grub shell.  I could boot again by running 'sudo btrfs filesystem defragment -r -clzo /' and specifying compress=lzo in the /etc/fstab.
  There is also a new bug in the btrfs tools:
  btrfs does recognize the option '-clzo' but not '-c lzo'.

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