Error while unlocking encrypted BCacheFS: Required key not available

[Martin Steigerwald <martin@lichtvoll.de>]

Hi!

Kernel 6.7.0-rc8 with BCacheFS new year fixes. Compliled with Debian gcc 
13.2.0-9.

BCacheFS tools 1.3.3 – according to bcachefs version – from Debian package 
bcachefs-tools 24+really1.3.4-2.

Linux kernel keyutils from Debian package keyutils 1.6.3-2+b2. (Not sure 
whether really required.)

Created BCacheFS on external 4 TB SSD:

% mkfs.bcachefs -L […] --data_checksum xxhash --metadata_checksum xxhash 
--compression=lz4 --encrypted /dev/sda1

(also tried without xxhash, no difference)


Unlock attempt with incorrect passphrase:

% bcachefs unlock /dev/sda1
Enter passphrase: 
incorrect passphrase

Unlock attempt with correct passphrase does not yield error message 
"incorrect passphrase". Key seems to be available:

% grep bcachefs /proc/keys
1b9e7153 I--Q---  1 perm 3f010000  0  0 user   bcachefs:[… UUID …]: 32

UUID matches filesystem.


Still I get:

% LANG=en mount /dev/sda1 /mnt/zeit
mount: /mnt/zeit: mount(2) system call failed: Required key not available.
       dmesg(1) may have more information after failed mount system call.

% dmesg | tail -1
[105441.695035] bcachefs ([…]): error requesting encryption key: ENOKEY


Why? And how to fix it?

I found

error requesting encryption key #93 

https://github.com/koverstreet/bcachefs/issues/93

But I am not sure whether it applies to my situation.

I use Devuan with elogind. Do I need that pam related configuration change 
from comment

https://github.com/koverstreet/bcachefs/issues/93#issuecomment-609430340

?

I do not like to do it in case it is not required.

Best,
-- 
Martin