[Libguestfs] RHEL 7 and guestmount of XFS volumes

[Richard W.M. Jones]

On Mon, Nov 25, 2019 at 12:08:33PM +0100, Fabien Dupont wrote:
> Hi,
> 
> I'm experiencing a weird behavior when tried to use guestmount with a XFS
> formatted volume. I have created a RHEL 8 virtual machine using libvirt. I
> have retrieved the disk image on a RHEL 7.7 server to mount the image root
> filesystem and explore it.
> 
> The command returns an error message:
> 
> # guestmount -a /disks/jamesdream.qcow2 -m /dev/sda1 /mnt/
> libguestfs: error: mount_options: mount exited with status 32: mount: wrong
> fs type, bad option, bad superblock on /dev/sda1,
>        missing codepage or helper program, or other error
> 
>        In some cases useful info is found in syslog - try
>        dmesg | tail or so.
> guestmount: ‘/dev/sda1’ could not be mounted.
> guestmount: Did you mean to mount one of these filesystems?
> guestmount: /dev/sda1 (xfs)
> guestmount: /dev/rhel/root (xfs)
> guestmount: /dev/rhel/swap (swap)
> 
> I have also run the same command with -x and -v options and the log is
> attached.
> 
> Seeing that it's not working on RHEL 7, I've tried the same command on
> another RHEL 8.1 machine and it works. Looking at libguestfs-tools package
> version, it appears that the package on RHEL 7.7 (1.40.2-5.el7_7.2) is more
> recent than on RHEL 8.1 (1.38.4-14.module+el8.1.0+4066+0f1aadab). Is that
> normal ?

Hi Fabien, sadly yes this is normal, it's a kernel "bug" (disputed):

https://bugzilla.redhat.com/show_bug.cgi?id=1667478

There's a somewhat hacky and definitely not supported workaround:

https://access.redhat.com/solutions/3914591

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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