Comment 0 for bug 1989677

After upgrading from 18.04 to 20.04, my computer failed to boot.

I eventually figured out that `btrfs device scan` does not detect all of the devices for my root filesystem, one of which is /dev/sdb10.

Is the program hardcoded to do this?

Workaround is to create /etc/initramfs-tools/scripts/local-premount/btrfs:

------
!/bin/sh

set -e

modprobe btrfs
/bin/btrfs device scan
/bin/btrfs device ready /dev/sdb10
------

I've had a quick look through device-scan.c from the upstream kernel but I don't see anything in there that would suggest it should be stopped after /dev/sdX9.

I'm sure this can be recreated fairly easily in a VM but I haven't tried that. I will do so if needed.

Related: https://askubuntu.com/q/1429429/170177

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: btrfs-progs 5.4.1-2
ProcVersionSignature: Ubuntu 5.4.0-126.142-generic 5.4.203
Uname: Linux 5.4.0-126-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.24
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Thu Sep 15 08:34:43 2022
SourcePackage: btrfs-progs
UpgradeStatus: Upgraded to focal on 2022-09-14 (1 days ago)
mtime.conffile..etc.apport.crashdb.conf: 2019-08-06T11:56:22.315382