libvirt users - May 2019 - Using qemu active blockcommit results in 'Permission denied' error

Hello all,

I tried following this guide:
https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit

Unfortunately when I try to do the final virsh blockcommit step I always
get the following error:

error: internal error: unable to execute QEMU command 'block-commit':
Could not reopen file: Permission denied

I checked directory und image file permissions, app-armor profiles (set
to complain mode for now.) and libvirt logs but nothing there gives me
any hints what might be going wrong.

This is on a debian buster system, using

libvirtd (libvirt) 5.0.0
qemu		   3.1+dfsg-7

I would appreciate any hints on how to proceed/get more debug info on this.

Thanks!
Marcus

On Thu, May 30, 2019 at 22:12:14 +0200, Marcus Hoffmann
wrote:
> Hello all,
Hi,
> 
> I tried following this guide:
> https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
> 
> Unfortunately when I try to do the final virsh blockcommit step I always
> get the following error:
> 
> error: internal error: unable to execute QEMU command
'block-commit':
> Could not reopen file: Permission denied
> 
> I checked directory und image file permissions, app-armor profiles (set
> to complain mode for now.) and libvirt logs but nothing there gives me
> any hints what might be going wrong.
> 
> This is on a debian buster system, using
I was doing some changes in the blockcommit code recently so I might
have messed something up. Could you please collect debug logs:

https://wiki.libvirt.org/page/DebugLogs

when the problem reproduces and also a directory listing of the path
where the image is stored so I can check if the permission code is
working properly.

Hi Peter,

On 31.05.19 09:57, Peter Krempa wrote:
> On Thu, May 30, 2019 at 22:12:14 +0200, Marcus Hoffmann wrote:
>> Hello all,
> 
> Hi,
> 
>>
>> I tried following this guide:
>> https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
>>
>> Unfortunately when I try to do the final virsh blockcommit step I
always
>> get the following error:
>>
>> error: internal error: unable to execute QEMU command
'block-commit':
>> Could not reopen file: Permission denied
>>
>> I checked directory und image file permissions, app-armor profiles (set
>> to complain mode for now.) and libvirt logs but nothing there gives me
>> any hints what might be going wrong.
>>
>> This is on a debian buster system, using
> 
> I was doing some changes in the blockcommit code recently so I might
> have messed something up. Could you please collect debug logs:
> 
> https://wiki.libvirt.org/page/DebugLogs
> 
> when the problem reproduces and also a directory listing of the path
> where the image is stored so I can check if the permission code is
> working properly.
> 

Logfile attached.

~ # ls -al /var/lib/libvirt/images/
total 1271917588
drwxr-xr-x 2 root         root                 4096 Mai 29 14:47 .
drwxr-xr-x 7 root         root                 4096 Mai 27 15:55 ..
-rw-r--r-- 1 libvirt-qemu libvirt-qemu 214821961728 Mai 29 14:47
drache3.qcow2
-rw-r--r-- 1 libvirt-qemu libvirt-qemu 395671371776 Mai 29 14:47
drache_addon.qcow2
-rw-r--r-- 1 libvirt-qemu libvirt-qemu  90944765952 Mai 31 14:02
drache_overlaya.qcow2
-rw-r--r-- 1 libvirt-qemu libvirt-qemu 115860766720 Mai 31 14:02
drache_overlayb.qcow2

Marcus