mounting an ubuntu 14.04 bhyve image as a filesystem for editing

[tech-lists]

On 10/11/2016 15:26, Lars Engels wrote:
> On Thu, Nov 10, 2016 at 12:32:07PM +0000, tech-lists wrote:
>> Hello list,
>>
>> [originally sent to virtualization@ but got no replies, probably
>> because, thinking about it, the fact that it's a bhyve image is incidental]
>>
>> [snipped stuff about bhyve]
>>
>> Is there a way of taking an ubuntu VM image that normally runs as a
>> bhyve guest, mounting it on some mountpoint on the freebsd host and
>> directly editing the files within it?
>>
>> Alternatively, is there a way of making grub boot the image into
>> single-user-mode like one can with freebsd?
>>
>
> That should work (provided sysutils/fusefs-ext4fuse is installed):
>
> # mdconfig -t vnode -f $ubuntu_img
> # ext4fuse /dev/md0 /mnt
>

Hi, thanks for looking at this.

Unfortunately it didn't work:

root at host0:/vms/138# mdconfig -t vnode -f ubuntu138.img
md2

root at host0:/vms/138# ext4fuse /dev/md2 /mnt
Partition doesn't contain EXT4 filesystem

root at host0:/vms/138# ls -la /dev/md2*
crw-r-----  1 root  operator  0xb0 Nov 11 14:58 /dev/md2
crw-r-----  1 root  operator  0xb4 Nov 11 15:06 /dev/md2s1
crw-r-----  1 root  operator  0xb5 Nov 11 15:06 /dev/md2s2
crw-r-----  1 root  operator  0xb6 Nov 11 15:06 /dev/md2s5

root at host0:/vms/138# ext4fuse /dev/md2s1 /mnt
fuse: failed to open fuse device: No such file or directory

root at host0:/vms/138# ext4fuse /dev/md2s2 /mnt
Partition doesn't contain EXT4 filesystem

root at host0:/vms/138# ext4fuse /dev/md2s5 /mnt
Partition doesn't contain EXT4 filesystem

I'm certain the defaults for 14.04 are ext4. Mind you, I upgraded this 
from ubuntu13.10. So it might be ext3.

I have ext2fs kernel module installed:

root at host0:/vms/138# kldstat | grep ext
13    1 0xffffffff81d90000 13c8e    ext2fs.ko
root at host0:/vms/138#

root at host0:/vms/138# mount -t ext2fs  /dev/md2 /mnt
mount: /dev/md2: Invalid argument

root at host0:/vms/138# mount -t ext2fs /dev/md2s1 /mnt
mount: /dev/md2s1: Invalid argument

root at host0:/vms/138# mount -t ext2fs /dev/md2s2 /mnt
mount: /dev/md2s2: Invalid argument

root at host0:/vms/138# mount -t ext2fs /dev/md2s5 /mnt
mount: /dev/md2s5: Invalid argument

As I understand it, this driver should also read ext3. Maybe bhyve does 
something meaning the filesystem in the image isn't readable as the 
installed filesystem of the image, to the host?

Do you have any other suggestions?

Many thanks,

-- 
J.