Bug 2173142

Summary:	[snapshot] cannot delete snapshot when one of the disk's snapshot mode is 'manual'
Product:	Red Hat Enterprise Linux 9	Reporter:	yisun
Component:	libvirt	Assignee:	Pavel Hrdina <phrdina>
libvirt sub component:	General	QA Contact:	yisun
Status:	VERIFIED ---	Docs Contact:
Severity:	medium
Priority:	medium	CC:	dzheng, jdenemar, lmen, pkrempa, virt-maint, ymankad
Version:	9.2	Keywords:	AutomationTriaged, Triaged
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libvirt-9.2.0-1.el9	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:	9.2.0
Embargoed:
Bug Depends On:
Bug Blocks:	1519002

Description yisun 2023-02-24 07:59:41 UTC

Description of problem:
cannot delete snapshot when one of the disk's snapshot mode is 'manual'

Version-Release number of selected component (if applicable):
libvirt-9.0.0-7.el9.x86_64

How reproducible:
100%

Steps to Reproduce:
1.have a running vm with two disks
[root@dell-per740-41 ~]# virsh domstate vm1
running

[root@dell-per740-41 ~]# virsh domblklist vm1
 Target   Source
---------------------------------------------
 vda      /var/lib/libvirt/images/vm1.qcow2
 vdb      /var/lib/libvirt/images/vdb.qcow2

2. prepare a snapshot xml, in which the vda's snapshot mode is 'manual'
[root@dell-per740-41 ~]# cat snap.xml 
<domainsnapshot>
	<description>Snapshot test</description>
	<name>snap1</name>
	<memory snapshot='external' file='/tmp/mem.dump'/>
	<disks>
		<disk name='vda' snapshot='manual'/>
		<disk name='vdb' snapshot='external'/>
	</disks>
</domainsnapshot>


3. do the snapshot
[root@dell-per740-41 ~]# virsh snapshot-create vm1 snap.xml 
Domain snapshot snap1 created from 'snap.xml'

now the vm is moved to PAUSED state, vda's path not chaged, and vdb has a new image layer 'vdb.snap1'

[root@dell-per740-41 ~]# virsh domstate vm1
paused

[root@dell-per740-41 ~]# virsh domblklist vm1
 Target   Source
---------------------------------------------
 vda      /var/lib/libvirt/images/vm1.qcow2
 vdb      /var/lib/libvirt/images/vdb.snap1

4. delete the snapshot
[root@dell-per740-41 ~]# virsh snapshot-delete vm1 snap1
error: Failed to delete snapshot snap1
error: invalid argument: could not find base disk source in disk source chain

[root@dell-per740-41 ~]# virsh resume vm1
Domain 'vm1' resumed

[root@dell-per740-41 ~]# virsh snapshot-delete vm1 snap1
error: Failed to delete snapshot snap1
error: invalid argument: could not find base disk source in disk source chain


Actual results:
snapshot cannot be removed if one of the disk has 'manual' mode for snapshot

Expected results:
libvirt should remove the snapshot data which is maintained by libvirt, such as the memory dump, vdb's new layer and snapshot's metadata

Additional info:
if vda's snapshot mode is 'no' then it works.

Comment 1 Pavel Hrdina 2023-03-20 09:58:45 UTC

Upstream commit:

commit 22a07239f5ea3d3ccd8a057cf83dcc09d6b7b0f0
Author: Pavel Hrdina <phrdina>
Date:   Wed Mar 1 12:51:21 2023 +0100

    qemu_snapshot: properly ignore disks with manual snapshot

Comment 2 yisun 2023-04-11 10:11:31 UTC

Preverified with:libvirt-9.2.0-1.el9.x86_64

[root@lenovo-sr630-14 ~]# virsh start vm1
Domain 'vm1' started

[root@lenovo-sr630-14 ~]# virsh domblklist vm1
 Target   Source
--------------------------------------------------------
 vda      /var/lib/libvirt/images/jeos-27-x86_64.qcow2
 vdb      /var/lib/libvirt/images/vdb.qcow2

[root@lenovo-sr630-14 ~]# vim snap.xml
<domainsnapshot>
	<description>Snapshot test</description>
	<name>snap1</name>
	<memory snapshot='external' file='/tmp/mem.dump'/>
	<disks>
		<disk name='vda' snapshot='manual'/>
		<disk name='vdb' snapshot='external'/>
	</disks>
</domainsnapshot>

[root@lenovo-sr630-14 ~]# virsh snapshot-create vm1 snap.xml
Domain snapshot snap1 created from 'snap.xml'

[root@lenovo-sr630-14 ~]#  virsh domstate vm1
paused

[root@lenovo-sr630-14 ~]# virsh domblklist vm1
 Target   Source
--------------------------------------------------------
 vda      /var/lib/libvirt/images/jeos-27-x86_64.qcow2
 vdb      /var/lib/libvirt/images/vdb.snap1

[root@lenovo-sr630-14 ~]# virsh dumpxml vm1 --xpath //disk
<disk type="file" device="disk">
  <driver name="qemu" type="qcow2"/>
  <source file="/var/lib/libvirt/images/jeos-27-x86_64.qcow2" index="2"/>
  <backingStore/>
  <target dev="vda" bus="virtio"/>
  <alias name="virtio-disk0"/>
  <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
</disk>
<disk type="file" device="disk">
  <driver name="qemu" type="qcow2"/>
  <source file="/var/lib/libvirt/images/vdb.snap1" index="3"/>
  <backingStore type="file" index="1">
    <format type="qcow2"/>
    <source file="/var/lib/libvirt/images/vdb.qcow2"/>
    <backingStore/>
  </backingStore>
  <target dev="vdb" bus="virtio"/>
  <alias name="virtio-disk1"/>
  <address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</disk>

[root@lenovo-sr630-14 ~]# virsh snapshot-delete vm1 snap1
error: Failed to delete snapshot snap1
error: internal error: unable to execute QEMU command 'block-commit': Block node is read-only

[root@lenovo-sr630-14 ~]# virsh resume vm1
Domain 'vm1' resumed

[root@lenovo-sr630-14 ~]# virsh snapshot-delete vm1 snap1
Domain snapshot snap1 deleted

[root@lenovo-sr630-14 ~]# virsh domblklist vm1
 Target   Source
--------------------------------------------------------
 vda      /var/lib/libvirt/images/jeos-27-x86_64.qcow2
 vdb      /var/lib/libvirt/images/vdb.qcow2

[root@lenovo-sr630-14 ~]# virsh dumpxml vm1 --xpath //disk
<disk type="file" device="disk">
  <driver name="qemu" type="qcow2"/>
  <source file="/var/lib/libvirt/images/jeos-27-x86_64.qcow2" index="2"/>
  <backingStore/>
  <target dev="vda" bus="virtio"/>
  <alias name="virtio-disk0"/>
  <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
</disk>
<disk type="file" device="disk">
  <driver name="qemu" type="qcow2"/>
  <source file="/var/lib/libvirt/images/vdb.qcow2" index="1"/>
  <backingStore/>
  <target dev="vdb" bus="virtio"/>
  <alias name="virtio-disk1"/>
  <address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</disk>

Comment 5 yisun 2023-05-19 08:43:42 UTC

test with libvirt-9.3.0-2.el9.x86_64 and result is PASS