Ubuntu
btrfs-progs package

btrfs dev scan fails to find all devices

Bug #1989677 reported by Ken Sharp
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
btrfs-progs (Ubuntu)
New
Undecided
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Bug Description

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

See original description
Revision history for this message
Ken Sharp (kennybobs) wrote :
Revision history for this message
Ken Sharp (kennybobs) wrote :

Arguably related: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=964906

description: updated
Revision history for this message
Ken Sharp (kennybobs) wrote (last edit ):

GParted Live 1.7.0 fails to correctly identify the partition when it loads also; a manual `btrfs dev scan` corrects this. Obviously this doesn't cause a boot failure, but as it is based on Debian Sid I would expect to see this in Debian also, possibly all the way upstream.

Revision history for this message
Ken Sharp (kennybobs) wrote :

Tried in a VM:

Install 18.04, add partitions to both sda and sdb up to 10, upgrade to 20.04, and it seems to work fine.

I don't know how to reproduce this reliably, but I definitely need the script to run on my system or it won't boot.

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