Thanks Kashyap for replying. 

QEMU has permissions to the directory which is having images. I will look into the AppArmor issue and find out more about this. 
Also as per suggestion from the link i have uncommented the user and group from the qemu.conf file - https://github.com/jedi4ever/veewee/issues/996

By checking more on the AppArmor and sVirt issue  , i have modified the qemu.conf for security_driver="none". The result for this is no permission error but another error which can be related to QEMU 2.3.0

virsh # blockcommit vm-01 vda --verbose --pivot --active
Block Commit: [100 %]error: failed to pivot job for disk vda
error: internal error: unable to execute QEMU command 'block-job-complete': The active block job for device 'drive-virtio-disk0' cannot be completed

Searched more for this type of error and found - 

https://bugs.launchpad.net/qemu/+bug/1455475

Looks like bug in QEMU 2.3.0 . Checking now with QEMU 2.1 for the same. 

Let me know if anything to more look for.

                                                                                                                                                                                                                    
Thanks,
Keyur Bhalerao


On Tue, Dec 8, 2015 at 5:18 AM, Kashyap Chamarthy <kchamart@redhat.com> wrote:
On Mon, Dec 07, 2015 at 12:52:34PM -0800, Keyur Bhalerao wrote:

[. . .]

 ubuntu@keyurubuntu:~$ virsh blockcommit vm-01 vda --active --verbose --pivot
> error: internal error: unable to execute QEMU command 'block-commit': Could
> not reopen file: Permission denied

Fairly obvious suggestions, ensure permissions are set so that QEMU has
permissions to the dir that contains images.

Or it could be an AppArmor issue.

Also, check your logs:

    /var/log/libvirt/qemu/$VM.log
    /var/log/libvirt/libvirtd.log  (assuming you have debug logging
    enabled)

> I am not sure why this is getting as permission denied. I have tried
> couple of times reinstalling and creating new VMs . Every time when i
> have tried to block-commit getting landed into  same error.
>
> Is there any troubleshooting or solution to this issue. Stuck on this
> issue for last 2 days.  Quick help much appreciated.
>
> Thanks, Keyur Bhalerao
>
> Reference used -
> http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit
> -
> http://kashyapc.com/2012/09/14/externaland-live-snapshots-with-libvirt/

--
/kashyap