Libguestfs - Nov 2017 - virt-builder resize error

Hi,

I was trying out virt-builder and noticed that in some directories I
receive an error when the image is resized.

For example, if I run the following command from my home directory it works
fine:

virt-builder rhel-7.4 --size 10G --output test.img

If I run the same command from /tmp or /vms (my default libvirt pool), I
see the following in my verbose output:

virt-resize '--verbose' '--format' 'raw'
'--output-format' 'raw' '--expand'
'/dev/sda3' '--unknown-filesystems' 'error'
'test.img' 'test.img'
command line: virt-resize --verbose --format raw --output-format raw
--expand /dev/sda3 --unknown-filesystems error test.img test.img
virt-resize: error: you cannot use the same disk image for input and output

Am I doing something wrong or is this possibly a bug? The host I am running
virt-builder on is Fedora 27.

Thanks,
David

Hi,

On Monday, 20 November 2017 22:57:04 CET David Kaylor
wrote:
> I was trying out virt-builder and noticed that in some directories I
> receive an error when the image is resized.
> 
> For example, if I run the following command from my home directory it works
> fine:
> 
> virt-builder rhel-7.4 --size 10G --output test.img
> 
> If I run the same command from /tmp or /vms (my default libvirt pool), I
> see the following in my verbose output:
> 
> virt-resize '--verbose' '--format' 'raw'
'--output-format' 'raw' '--expand'
> '/dev/sda3' '--unknown-filesystems' 'error'
'test.img' 'test.img'
> command line: virt-resize --verbose --format raw --output-format raw
> --expand /dev/sda3 --unknown-filesystems error test.img test.img
> virt-resize: error: you cannot use the same disk image for input and output
> 
> Am I doing something wrong or is this possibly a bug? The host I am running
> virt-builder on is Fedora 27.
The only thing it comes into my mind is that there is already a file
called "test.img" in the directories where it fails.

Can you please check that, and provide also a full log virt-builder
with -v -x?

Thanks,
-- 
Pino Toscano

On Tue, Nov 21, 2017 at 3:55 AM, Pino Toscano <ptoscano@redhat.com> wrote:
> Hi,
>
> On Monday, 20 November 2017 22:57:04 CET David Kaylor wrote:
> > I was trying out virt-builder and noticed that in some directories I
> > receive an error when the image is resized.
> >
> > For example, if I run the following command from my home directory it
> works
> > fine:
> >
> > virt-builder rhel-7.4 --size 10G --output test.img
> >
> > If I run the same command from /tmp or /vms (my default libvirt pool),
I
> > see the following in my verbose output:
> >
> > virt-resize '--verbose' '--format' 'raw'
'--output-format' 'raw'
> '--expand'
> > '/dev/sda3' '--unknown-filesystems' 'error'
'test.img' 'test.img'
> > command line: virt-resize --verbose --format raw --output-format raw
> > --expand /dev/sda3 --unknown-filesystems error test.img test.img
> > virt-resize: error: you cannot use the same disk image for input and
> output
> >
> > Am I doing something wrong or is this possibly a bug? The host I am
> running
> > virt-builder on is Fedora 27.
>
> The only thing it comes into my mind is that there is already a file
> called "test.img" in the directories where it fails.
>
> Can you please check that, and provide also a full log virt-builder
> with -v -x?
>
> Thanks,
> --
> Pino Toscano

Thanks, Pino. Attached is the requested log. A few other observations:

In most directories, I can run the command successfully whether a file of
the same name is present or not.

Looking at the verbose output, it appears that a randomly-generated name in
/var/tmp is used for the indisk. Example:

virt-resize --verbose --format raw --output-format raw --expand /dev/sda3
--unknown-filesystems error /var/tmp/vbaf3053.img test.img

For directories where it fails, both the indisk and outdisk are the same:

virt-resize --verbose --format raw --output-format raw --expand /dev/sda3
--unknown-filesystems error test.img test.img

-David