vmWithDisko is unable to mount bcachefs volume #1216
Description
When using bcachefs as the root filesystem in a disko configuration, the interactive VM (vmWithDisko) fails to boot with the error:
mount: /tmp/tmp.QuzLxZxace: unknown filesystem type 'bcachefs'
loading kernel modules...
mounting Nix store...
mounting host's temporary directory...
starting stage 2 (/nix/store/5cqacs2w30rd86fb6vg3a2afj71dg1nn-vm-run-stage2)
+++ echo 'running udev...'
running udev...
+++ ln -sfn /proc/self/fd /dev/fd
+++ ln -sfn /proc/self/fd/0 /dev/stdin
+++ ln -sfn /proc/self/fd/1 /dev/stdout
+++ ln -sfn /proc/self/fd/2 /dev/stderr
+++ mkdir -p /etc/udev
+++ mount -t efivarfs none /sys/firmware/efi/efivars
+++ ln -sfn /nix/store/k8gimq3n74b9cyqyxn8pnqjay7qb1fz6-etc/etc/udev/rules.d /etc/udev/rules.d
+++ mkdir -p /dev/.mdadm
+++ /nix/store/kna7cma80icar3xwbznwp63fx4602fqq-systemd-minimal-258.3/lib/systemd/systemd-udevd --daemon
Starting systemd-udevd version 258.3
+++ partprobe
+++ udevadm trigger --action=add
+++ udevadm settle --timeout=120
[ 2.855799] Error: Driver 'pcspkr' is already registered, aborting...
+++ export IN_DISKO_TEST=1
+++ IN_DISKO_TEST=1
+++ /nix/store/yvpjza29mqf41mrxhckcl044fjq7gxbr-disko-destroy-format-mount/bin/disko-destroy-format-mount --yes-wipe-all-disks
umount: /mnt: not found
++ realpath /dev/vda
+ disk=/dev/vda
+ lsblk -a -f
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
fd0
vda
+ lsblk --output-all --json
+ bash -x
++ dirname /nix/store/fpwn44vygjj6bfn8s1jj9p8yh6jhfxni-disk-deactivate/disk-deactivate
+ jq -r -f /nix/store/fpwn44vygjj6bfn8s1jj9p8yh6jhfxni-disk-deactivate/zfs-swap-deactivate.jq
+ lsblk --output-all --json
+ bash -x
++ dirname /nix/store/fpwn44vygjj6bfn8s1jj9p8yh6jhfxni-disk-deactivate/disk-deactivate
+ jq -r --arg disk_to_clear /dev/vda -f /nix/store/fpwn44vygjj6bfn8s1jj9p8yh6jhfxni-disk-deactivate/disk-deactivate.jq
+ set -fu
++ type zdb
++ zdb -l /dev/vda
++ sed -nr 's/ +name: '\''(.*)'\''/\1/p'
+ zpool=
+ [[ -n '' ]]
+ unset zpool
++ lsblk /dev/vda -l -p -o type,name
++ awk 'match($1,"raid.*") {print $2}'
+ md_dev=
+ [[ -n '' ]]
+ wipefs --all -f /dev/vda
+ dd if=/dev/zero of=/dev/vda bs=440 count=1
1+0 records in
1+0 records out
440 bytes copied, 0.000312807 s, 1.4 MB/s
+ lsblk -a -f
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
fd0
vda
++ mktemp -d
+ disko_devices_dir=/tmp/tmp.on6Tu3NuPA
+ trap 'rm -rf "$disko_devices_dir"' EXIT
+ mkdir -p /tmp/tmp.on6Tu3NuPA
+ destroy=1
+ device=/dev/vda
+ imageName=disk1
+ imageSize=2G
+ name=disk1
+ type=disk
+ device=/dev/vda
+ efiGptPartitionFirst=1
+ type=gpt
+ blkid /dev/vda
+ sgdisk --clear /dev/vda
Creating new GPT entries in memory.
The operation has completed successfully.
+ sgdisk --align-end --new=1:0:+1M --partition-guid=1:R --change-name=1:disk-disk1-boot --typecode=1:EF02 --attributes=1:=:0 /dev/vda
The operation has completed successfully.
+ partprobe /dev/vda
+ udevadm trigger --subsystem-match=block
+ udevadm settle --timeout 120
+ sgdisk --align-end --new=2:0:+500M --partition-guid=2:R --change-name=2:disk-disk1-ESP --typecode=2:EF00 --attributes=2:=:0 /dev/vda
The operation has completed successfully.
+ partprobe /dev/vda
+ udevadm trigger --subsystem-match=block
+ udevadm settle --timeout 120
+ sgdisk --align-end --new=3:0:-0 --partition-guid=3:R --change-name=3:disk-disk1-bcachefs --typecode=3:8300 --attributes=3:=:0 /dev/vda
The operation has completed successfully.
+ partprobe /dev/vda
+ udevadm trigger --subsystem-match=block
+ udevadm settle --timeout 120
+ device=/dev/disk/by-partlabel/disk-disk1-ESP
+ extraArgs=()
+ declare -a extraArgs
+ format=vfat
+ mountOptions=('umask=0077')
+ declare -a mountOptions
+ mountpoint=/boot
+ type=filesystem
+ blkid /dev/disk/by-partlabel/disk-disk1-ESP
+ grep -q TYPE=
+ mkfs.vfat /dev/disk/by-partlabel/disk-disk1-ESP
mkfs.fat 4.2 (2021-01-31)
+ device=/dev/disk/by-partlabel/disk-disk1-bcachefs
+ extraFormatArgs=('--discard' '--compression=zstd:6')
+ declare -a extraFormatArgs
+ filesystem=bcachefs_desktop
+ label=bcachefs_desktop
+ type=bcachefs
+ printf '%s\n' --label=bcachefs_desktop
+ printf '%s\n' --discard
+ printf '%s\n' --compression=zstd:6
+ printf '%s\n' /dev/disk/by-partlabel/disk-disk1-bcachefs
+ extraFormatArgs=()
+ declare -a extraFormatArgs
+ mountOptions=('X-mount.mkdir')
+ declare -a mountOptions
+ mountpoint=
+ name=bcachefs_desktop
+ passwordFile=
+ type=bcachefs_filesystem
+ uuid=057886fd-6985-12ce-5ce4-4798889d19fa
+ test -s /tmp/tmp.on6Tu3NuPA/bcachefs-bcachefs_desktop
+ set --
+ IFS=
+ read -r line
+ set -- --label=bcachefs_desktop
+ IFS=
+ read -r line
+ set -- --label=bcachefs_desktop --discard
+ IFS=
+ read -r line
+ set -- --label=bcachefs_desktop --discard --compression=zstd:6
+ IFS=
+ read -r line
+ set -- --label=bcachefs_desktop --discard --compression=zstd:6 /dev/disk/by-partlabel/disk-disk1-bcachefs
+ IFS=
+ read -r line
+ grep -q TYPE=bcachefs
++ blkid -lU 057886fd-6985-12ce-5ce4-4798889d19fa
[ 9.449380] I/O error, dev fd0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
[ 9.492289] I/O error, dev fd0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
+ blkid -o export ''
+ bcachefs format --label=bcachefs_desktop --discard --compression=zstd:6 /dev/disk/by-partlabel/disk-disk1-bcachefs --uuid=057886fd-6985-12ce-5ce4-4798889d19fa
External UUID: 057886fd-6985-12ce-5ce4-4798889d19fa
Internal UUID: a0221e82-60f1-46f3-917b-b025401fd991
Magic number: c68573f6-66ce-90a9-d96a-60cf803df7ef
Device index: 0
Label: (none)
Version: no_sb_user_data_replicas (1.36)
Incompatible features allowed: no_sb_user_data_replicas (1.36)
Incompatible features in use: (unknown version) (0.0)
Version upgrade complete: (unknown version) (0.0)
Oldest version on disk: no_sb_user_data_replicas (1.36)
Created: Fri Feb 20 12:48:19 2026
Sequence number: 0
Time of last write: Thu Jan 1 00:00:00 1970
Superblock size: 1.08k/1.00M
Clean: 0
Devices: 1
Sections: members_v1,disk_groups,members_v2
Features: new_siphash,new_extent_overwrite,btree_ptr_v2,extents_above_btree_updates,btree_updates_journalled,new_varint,journal_no_flush,alloc_v2,extents_across_btree_nodes,incompat_version_field
Compat features:
Options:
block_size: 512
btree_node_size: 256k
errors: continue [fix_safe] panic ro
write_error_timeout: 30
metadata_replicas: 1
data_replicas: 1
encoded_extent_max: 256k
metadata_checksum: none [crc32c] crc64 xxhash
data_checksum: none [crc32c] crc64 xxhash
checksum_err_retry_nr: 3
compression: zstd:6
background_compression: none
str_hash: crc32c crc64 [siphash]
metadata_target: none
foreground_target: none
background_target: none
promote_target: none
erasure_code: 0
casefold: 0
inodes_32bit: 0
shard_inode_numbers_bits: 0
gc_reserve_percent: 8
gc_reserve_bytes: 0
root_reserve_percent: 0
wide_macs: 0
promote_whole_extents: 1
acl: 1
usrquota: 0
grpquota: 0
prjquota: 0
degraded: [ask] yes very no
journal_flush_delay: 1000
journal_flush_disabled: 0
journal_reclaim_delay: 100
writeback_timeout: 0
journal_transaction_names: 1
allocator_stuck_timeout: 30
version_upgrade: [compatible] incompatible none
nocow: 0
reconcile_on_ac_only: 0
Device 0: /dev/vda3 (unknown model)
Label: bcachefs_desktop
UUID: 3e761256-bbdc-437e-93d4-a611cdfb3c85
Size: 1.50G
read errors: 0
write errors: 0
checksum errors: 0
seqread iops: 0
seqwrite iops: 0
randread iops: 0
randwrite iops: 0
Bucket size: 512k
First bucket: 0
Buckets: 3090
Last mount: (never)
Last superblock write: 0
State: rw
Data allowed: journal,btree,user
Has data: (none)
Rotational: 0
Btree allocated bitmap blocksize: 1
Btree allocated bitmap: 0000000000000000000000000000000000000000000000000000000000000000
Durability: 1
Discard: 1
Freespace initialized: 0
Resize on mount: 0
Last device name:
Last device model:
Using encoding defined by superblock: utf8-12.1.0
starting version no_sb_user_data_replicas (1.36)
initializing new filesystem
going read-write
initializing freespace
clean shutdown complete, journal seq 7
+ grep -q TYPE=bcachefs
++ blkid -lU 057886fd-6985-12ce-5ce4-4798889d19fa
+ blkid -o export /dev/vda3
++ mktemp -d
+ TEMPDIR=/tmp/tmp.WKmjcCUtKF
++ mktemp -d
+ MNTPOINT=/tmp/tmp.QuzLxZxace
+ mount -t bcachefs -o X-mount.mkdir /dev/disk/by-uuid/057886fd-6985-12ce-5ce4-4798889d19fa /tmp/tmp.QuzLxZxace
mount: /tmp/tmp.QuzLxZxace: unknown filesystem type 'bcachefs'.
dmesg(1) may have more information after failed mount system call.
+ rm -rf /tmp/tmp.on6Tu3NuPA
+ exitHandler
+ exitCode=32
+ set +e
+ '[' -n '' ']'
+ (( 32 != 0 ))
+ runHook failureHook
+ local hookName=failureHook
+ shift
+ local 'hooksSlice=failureHooks[@]'
+ local hook
+ for hook in "_callImplicitHook 0 $hookName" ${!hooksSlice+"${!hooksSlice}"}
+ _logHook failureHook '_callImplicitHook 0 failureHook'
+ [[ -z 2 ]]
+ local hookKind=failureHook
+ local 'hookExpr=_callImplicitHook 0 failureHook'
+ shift 2
+ declare -F '_callImplicitHook 0 failureHook'
+ type -p '_callImplicitHook 0 failureHook'
+ [[ _callImplicitHook 0 failureHook != _callImplicitHook* ]]
+ _eval '_callImplicitHook 0 failureHook'
+ declare -F '_callImplicitHook 0 failureHook'
+ eval '_callImplicitHook 0 failureHook'
++ _callImplicitHook 0 failureHook
++ local def=0
++ local hookName=failureHook
++ declare -F failureHook
++ type -p failureHook
++ '[' -n '' ']'
++ return 0
+ return 0
+ '[' -n '' ']'
+ return 32
[ 10.147517] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00002000
[ 10.149237] CPU: 13 UID: 0 PID: 1 Comm: 5cqacs2w30rd86f Not tainted 6.19.0 #1-NixOS PREEMPT(voluntary)
[ 10.151270] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022
[ 10.153094] Call Trace:
[ 10.153643] <TASK>
[ 10.154187] dump_stack_lvl+0x5d/0x80
[ 10.155063] vpanic+0xdb/0x2d0
[ 10.155738] panic+0x6b/0x6b
[ 10.156423] do_exit.cold+0x15/0x15
[ 10.157228] ? handle_mm_fault+0x1d9/0x2e0
[ 10.158167] do_group_exit+0x2d/0xc0
[ 10.158990] __x64_sys_exit_group+0x18/0x20
[ 10.159861] x64_sys_call+0x14fd/0x1510
[ 10.160706] do_syscall_64+0xb6/0x560
[ 10.161564] ? exc_page_fault+0x6a/0x150
[ 10.162450] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 10.163564] RIP: 0033:0x7f8bfa6ee118
[ 10.164377] Code: ff 64 89 02 eb b4 e8 d7 4e 04 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8b 35 d5 dc 10 00 eb 04 0f 1f 00 f4 b8 e7 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 f0 f7 d8 64 89 06 eb e9 66 0f 1f 84 00 00 00
[ 10.168365] RSP: 002b:00007ffcd60c5958 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[ 10.170034] RAX: ffffffffffffffda RBX: 00007f8bfa7fdfc8 RCX: 00007f8bfa6ee118
[ 10.171539] RDX: 0000000000000000 RSI: ffffffffffffffa0 RDI: 0000000000000020
[ 10.173111] RBP: 00007ffcd60c59b0 R08: 0000000000000000 R09: 0000000000000000
[ 10.174619] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
[ 10.176194] R13: 0000000000000020 R14: 00007f8bfa7fc680 R15: 00007f8bfa7fdfe0
[ 10.177705] </TASK>
[ 10.179453] Kernel Offset: 0xd000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[ 11.361726] Rebooting in 1 seconds..
[2026-02-20T12:48:23Z INFO virtiofsd] Client disconnected, shutting down
[2026-02-20T12:48:23Z INFO virtiofsd] Client disconnected, shutting down
Virtual machine didn't produce an exit code.
With a disko template:
{ lib, pkgs, ... }:
{
boot.supportedFilesystems = [ "bcachefs" ];
boot.kernelPackages = lib.mkDefault pkgs.linuxPackages_latest;
environment.systemPackages = [ pkgs.bcachefs-tools ];
virtualisation.vmVariantWithDisko = {
virtualisation.cores = 2;
virtualisation.memorySize = 2 * 1024;
};
disko.devices = {
disk.disk1 = {
device = lib.mkDefault "/dev/sda";
type = "disk";
content = {
type = "gpt";
partitions = {
boot = {
name = "boot";
size = "1M";
type = "EF02";
};
esp = {
name = "ESP";
size = "500M";
type = "EF00";
content = {
type = "filesystem";
format = "vfat";
mountpoint = "/boot";
mountOptions = [ "umask=0077" ];
};
};
root = {
name = "bcachefs";
size = "100%";
content = {
type = "bcachefs";
filesystem = "bcachefs_desktop";
label = "bcachefs_desktop";
extraFormatArgs = [
"--discard"
"--compression=zstd:6"
];
};
};
};
};
};
bcachefs_filesystems = {
bcachefs_desktop = {
type = "bcachefs_filesystem";
subvolumes = {
"root" = {
mountpoint = "/";
mountOptions = [
"noatime"
];
};
"home" = {
mountpoint = "/home";
mountOptions = [
"noatime"
];
};
"nix" = {
mountpoint = "/nix";
mountOptions = [
"noatime"
];
};
"persist" = {
mountpoint = "/persist";
mountOptions = [
"noatime"
];
};
"log" = {
mountpoint = "/var/log";
mountOptions = [
"noatime"
];
};
};
};
};
};
};I've tried
- Setting
boot.supportedFilesystems = [ "bcachefs" ] - Using
boot.kernelPackages = pkgs.linuxPackages_latest - Including
bcachefs-toolsinenvironment.systemPackages