Resizing luks encrypted disks fails with "unable to execute QEMU command 'block_resize': Cannot grow device files"

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1

ONE 6.8.0.1
i’m currently trying to resize luks encrypted disks attached to VMs. the systemds is a iscsi san storage.
when i try to resize the disk i get the error

Wed Jan 15 14:16:44 2025 [Z0][VMM][D]: Message received: RESIZEDISK FAILURE 6 ERROR: resize_disk: Command "virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdb 6144M" failed: error: Failed to resize block device 'vdb' error: internal error: unable to execute QEMU command 'block_resize': Cannot grow device files Failed to resize disk 2 on 490a48b5-4d33-4384-aa7c-0e8530b02af5 ExitCode: 1
2

did a little bit of testing and noticed:

Thu Jan 16 10:17:36 2025 [Z0][VMM][D]: Message received: RESIZEDISK FAILURE 6 ERROR: resize_disk: Command "virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdc 512M" failed: error: Failed to resize block device 'vdc' error: internal error: unable to execute QEMU command 'block_resize': Cannot grow device files Failed to resize disk 4 on 490a48b5-4d33-4384-aa7c-0e8530b02af5 ExitCode: 1

Thu Jan 16 10:17:39 2025 [Z0][ReM][D]: Req:3456 UID:0 IP:127.0.0.1 one.zone.raftstatus invoked 
Thu Jan 16 10:17:39 2025 [Z0][ReM][D]: Req:3456 UID:0 one.zone.raftstatus result SUCCESS, "<RAFT><SERVER_ID>1</..."
^C
[oneadmin@one2 ~]$ virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdc 512M
error: Failed to resize block device 'vdc'
error: internal error: unable to execute QEMU command 'block_resize': Cannot grow device files

[oneadmin@one2 ~]$ virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdc 0
Block device 'vdc' is resized
[oneadmin@one2 ~]$ 

Thu Jan 16 10:19:15 2025 [Z0][VMM][D]: Message received: RESIZEDISK FAILURE 6 ERROR: resize_disk: Command "virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdc 768M" failed: error: Failed to resize block device 'vdc' error: internal error: unable to execute QEMU command 'block_resize': Cannot grow device files Failed to resize disk 4 on 490a48b5-4d33-4384-aa7c-0e8530b02af5 ExitCode: 1

^C
[oneadmin@one2 ~]$ virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdc 768M
error: Failed to resize block device 'vdc'
error: internal error: unable to execute QEMU command 'block_resize': Cannot grow device files

[oneadmin@one2 ~]$ virsh --connect qemu:///system blockresize 490a48b5-4d33-4384-aa7c-0e8530b02af5 vdc 760M
Block device 'vdc' is resized
3

i think it’s related to

# Extend the SIZE so the encrypted file fits in the LV
if [[ "$FILE_TYPE" =~ "LUKS encrypted file" ]]; then
    SIZE=$(( SIZE + 4 ))
fi

in tm/fs_lvm/clone

changing

retry_if "is in use" 3 5 \
    exec_and_log "virsh --connect ${LIBVIRT_URI} blockresize ${DOMAIN} ${DISK_TARGET} ${DISK_SIZE}M" \
    "Failed to resize disk ${DISK_ID} on ${DOMAIN}"

to

retry_if "is in use" 3 5 \
    exec_and_log "virsh --connect ${LIBVIRT_URI} blockresize ${DOMAIN} ${DISK_TARGET} 0" \
    "Failed to resize disk ${DISK_ID} on ${DOMAIN}"

seems to fix the issue, i’m not sure about the conseques though, because the qemu/libvirt luks encryption is new to me.