Just following up, this is indeed an apparmor issue. The attachment work with apparmor disabled. This is a libvirt bug: https://bugzilla.redhat.com/show_bug.cgi?id=1361592 On Mon, Aug 22, 2016 at 2:26 PM, Erlon Cruz <sombrafam@gmail.com> wrote:
If that was the case I wouldn't be able to attach a volume without snapshots. But just in case I did the following test, before attaching the file, I copied all the file to a local folder and changed the path in XML with the new paths. The problem repeats:
*2016-08-22 17:14:19.795+0000: 3799: info : qemuMonitorIOProcess:423 : QEMU_MONITOR_IO_PROCESS: mon=0x7f68f800c4c0 buf={"return": "Could not open backing file: Could not open '/home/ubuntu/volumes/volume-d81f7e7e-4215-4433-aad2-50adcd31b29d.7a9ea169-a3ab-48bd-bd9d-e7585860abe4': Permission denied\r\n", "id": "libvirt-30"}*
But, if I use the top backing file with same permissions (/home/ubuntu/volumes/volume-d81f7e7e-4215-4433-aad2-50adcd31b29d), the operation suceeds. Can this be a libvirt/QEMU bug?
Han, can you tell me more details about the commands you used and the versions of or libvirt/qemu? I couldn't reproduce from the steps you outlined.
On Fri, Aug 19, 2016 at 12:02 AM, Han Han <hhan@redhat.com> wrote:
Hi Erlon, Since you say you got Permission denied error while the ACL mode is 777， I guess it is due to security system like selinux or apparmor. As I know, selinux defaultly will disable qemu to use volume based on NFS. We need to use 'setsebool virt_use_nfs 1' to enable it. Well, your OS is ubuntu, so I think apparmor causes the permission problem. Try to find a way to enable virt_use_nfs or disable apparmor. Then check if the problem can be reproduced.
Han
----- Original Message ----- From: "Erlon Cruz" <sombrafam@gmail.com> To: "Han Han" <hhan@redhat.com> Cc: "Yang Yang" <yanyang@redhat.com>, "Yuan Dan" <dyuan@redhat.com>, "Xuesong Zhang" <xuzhang@redhat.com>, libvirt-users@redhat.com Sent: Thursday, 18 August, 2016 12:44:36 PM Subject: Re: [libvirt-users] Attaching disks with external snapshots
Hi Han,
Any update on this?
Erlon
On Wed, Aug 17, 2016 at 9:58 AM, Erlon Cruz <sombrafam@gmail.com> wrote:
Han,
Did the same test again with libvirt debug enabled. This time I added the disk[1] without snaps (OK), and then added the disk[2] with snapshots. The libvirt log[3] (line 320) says:
*Could not open '/opt/stack/data/nova/mnt/a3b4c6ddd9bf82edd4f726872be58d05/ volume-a75b42e8-8175-4516-b724-43ee6f3d2520': Permission denied\r\n", "id": "libvirt-33"}]*
But this file has 777 permissions. I can access it with any user I tried[4]. Tough its mounted over NFS, the permissions seems to be right.
Erlon
[1] http://paste.openstack.org/show/556055/ [2] http://paste.openstack.org/show/556056/ [3] http://pastebin.com/CCFcKq5b [4] http://paste.openstack.org/show/559018/
On Tue, Aug 16, 2016 at 2:41 PM, Erlon Cruz <sombrafam@gmail.com> wrote:
Hi Han,
Thanks for helping. What is the XML before the snapshot is created? Can you post the XML files you used too? The files are in the links pointed by the numbers [1], [2] etc.
The versions are: qemu-system-x86_64 --version QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.4), Copyright (c) 2003-2008 Fabrice Bellard
libvirtd --version libvirtd (libvirt) 1.3.1
Erlon
On Mon, Aug 15, 2016 at 12:56 AM, Han Han <hhan@redhat.com> wrote:
Hi，Erlon I was not able to reproduce your problem. It is ok to attach disk with external snapshot. I did it with following steps: # qemu-img create /tmp/vdb 100M Formatting '/tmp/vdb', fmt=raw size=104857600 # virsh start snap Domain snap started # virsh snapshot-create-as snap s1 --disk-only --diskspec vdb,file=/tmp/vdb.s1 --quiesce Domain snapshot s1 created # virsh dumpxml snap|awk '/<disk/,/<\/disk/' <disk type='file' device='disk'> <driver name='qemu' type='qcow2' cache='none'/> <source file='/var/lib/libvirt/images/snap.s1'/> <backingStore type='file' index='1'> <format type='qcow2'/> <source file='/var/lib/libvirt/images/snap.qcow2'/> <backingStore/> </backingStore> <target dev='vda' bus='virtio'/> <alias name='virtio-disk0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/> </disk> <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/tmp/vdb.s1'/> <backingStore type='file' index='1'> <format type='raw'/> <source file='/tmp/vdb'/> <backingStore/> </backingStore> <target dev='vdb' bus='virtio'/> <alias name='virtio-disk1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/> </disk>
Save the dumped vdb's xml to /tmp/vdb.xml # virsh detach-device snap /tmp/vdb.xml Device detached successfully # virsh attach-device snap /tmp/vdb.xml Device attached successfully # virsh dumpxml snap|awk '/<disk/,/<\/disk/' <disk type='file' device='disk'> <driver name='qemu' type='qcow2' cache='none'/> <source file='/var/lib/libvirt/images/snap.s1'/> <backingStore type='file' index='1'> <format type='qcow2'/> <source file='/var/lib/libvirt/images/snap.qcow2'/> <backingStore/> </backingStore> <target dev='vda' bus='virtio'/> <alias name='virtio-disk0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/> </disk> <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/tmp/vdb.s1'/> <backingStore type='file' index='1'> <format type='raw'/> <source file='/tmp/vdb'/> <backingStore/> </backingStore> <target dev='vdb' bus='virtio'/> <alias name='virtio-disk1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/> </disk>
So I managed to attach disks with snapshot. I want to know what is your libvirt and qemu-kvm version? And can you provide your files: /tmp/disk.xml[1], /tmp/snap-from-disk.xml[2], /tmp/disk-with-snap.xml[4], /tmp/disk-with-snap.xml . I need more details.
Han Han
----- Original Message ----- From: "Erlon Cruz" <sombrafam@gmail.com> To: libvirt-users@redhat.com Sent: Friday, August 12, 2016 10:23:24 AM Subject: [libvirt-users] Attaching disks with external snapshots
Hi folks,
I'm trying to to attach a disk to an instance using libvirt. The problem is, this disk has external snapshots. The process tried was:
1 - Attach a disk in the domain: virsh# attach-device instance-00000006 /tmp/disk.xml[1] --live
2 - Snapshot the disk[2]: virsh# snapshot-create instance-00000006 --quiesce --xmlfile /tmp/snap-from-disk.xml[2] --disk-only
3 - Dump the domain XML and create a new disk file from it: virsh# dumpxml instance-00000006 ... [3]
4 - Dettach the device and re-add it using the new disk file: virsh# detach-device instance-00000006 /tmp/disk-with-snap.xml[4] Device detached successfully virsh# attach-device instance-00000006 /tmp/disk-with-snap.xml error: Failed to attach device from /tmp/disk-with-snap.xml error: internal error: unable to execute QEMU command 'device_add': Property 'virtio-blk-device.drive' can't find value 'drive-virtio-disk1'
Question, is this operation supported? If yes, how is the correct procedure?
Erlon
[1] http://paste.openstack.org/show/556055/ [2] http://paste.openstack.org/show/556056/ [3] http://paste.openstack.org/show/556063/ [4] http://paste.openstack.org/show/556064/
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