Created attachment 1642673 [details]
libvirtd log

Description:
[blockdev enablement] block pull failed when vm has multiple snapshots

Versions:
qemu-kvm-4.2.0-1.module+el8.2.0+4793+b09dd2fb.x86_64
libvirt-5.10.0-1.module+el8.2.0+5040+bd433686.x86_64

How reproducible:
100%

Steps:
1. Have a running vm
(.libvirt-ci-venv-ci-runtest-jUzTYn) [root@libvirt-rhel-8 ~]# virsh destroy avocado-vt-vm1; virsh start avocado-vt-vm1
Domain avocado-vt-vm1 destroyed

Domain avocado-vt-vm1 started

(.libvirt-ci-venv-ci-runtest-jUzTYn) [root@libvirt-rhel-8 ~]# ps -ef | grep avocado-vt-vm1
qemu      2960     1 91 12:08 ?        00:00:07 /usr/libexec/qemu-kvm -name guest=avocado-vt-vm1,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-21-avocado-vt-vm1/master-key.aes -machine pc-q35-rhel8.1.0,accel=kvm,usb=off,dump-guest-core=off -cpu Skylake-Server-IBRS,ss=on,hypervisor=on,tsc-adjust=on,clflushopt=on,umip=on,pku=on,md-clear=on,stibp=on,arch-capabilities=on,ssbd=on,ibpb=on,amd-ssbd=on,skip-l1dfl-vmentry=on,vmx=off -m 1024 -overcommit mem-lock=off -smp 2,sockets=2,cores=1,threads=1 -uuid 9f672c02-487d-45df-965f-49b2870dd948 -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=38,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=delay -no-hpet -no-shutdown -global ICH9-LPC.disable_s3=1 -global ICH9-LPC.disable_s4=1 -boot strict=on -device pcie-root-port,port=0x10,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x2 -device pcie-root-port,port=0x11,chassis=2,id=pci.2,bus=pcie.0,addr=0x2.0x1 -device pcie-root-port,port=0x12,chassis=3,id=pci.3,bus=pcie.0,addr=0x2.0x2 -device pcie-root-port,port=0x13,chassis=4,id=pci.4,bus=pcie.0,addr=0x2.0x3 -device pcie-root-port,port=0x14,chassis=5,id=pci.5,bus=pcie.0,addr=0x2.0x4 -device pcie-root-port,port=0x15,chassis=6,id=pci.6,bus=pcie.0,addr=0x2.0x5 -device pcie-root-port,port=0x16,chassis=7,id=pci.7,bus=pcie.0,addr=0x2.0x6 -device qemu-xhci,p2=15,p3=15,id=usb,bus=pci.2,addr=0x0 -device virtio-serial-pci,id=virtio-serial0,bus=pci.3,addr=0x0 -blockdev {"driver":"file","filename":"/var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"} -blockdev {"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage","backing":null} -device virtio-blk-pci,scsi=off,bus=pcie.0,addr=0x5,drive=libvirt-1-format,id=virtio-disk0,bootindex=1 -netdev tap,fd=40,id=hostnet0,vhost=on,vhostfd=41 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:ba:73:b3,bus=pci.1,addr=0x0 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,fd=42,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -device usb-tablet,id=input0,bus=usb.0,port=1 -vnc 127.0.0.1:1 -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pcie.0,addr=0x1 -device virtio-balloon-pci,id=balloon0,bus=pci.5,addr=0x0 -object rng-random,id=objrng0,filename=/dev/urandom -device virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny -msg timestamp=on

2. Clear libvirtd debug log
(.libvirt-ci-venv-ci-runtest-jUzTYn) [root@libvirt-rhel-8 ~]# echo "" > /var/log/libvirtd-debug.log

3. Create 4 external snapshots
(.libvirt-ci-venv-ci-runtest-jUzTYn) [root@libvirt-rhel-8 ~]# for i in {1..4}; do virsh snapshot-create-as avocado-vt-vm1 snap$i --disk-only; done
Domain snapshot snap1 created
Domain snapshot snap2 created
Domain snapshot snap3 created
Domain snapshot snap4 created
(.libvirt-ci-venv-ci-runtest-jUzTYn) [root@libvirt-rhel-8 ~]# virsh dumpxml avocado-vt-vm1 | awk '/<disk/,/<\/disk/'
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.snap4' index='5'/>
      <backingStore type='file' index='4'>
        <format type='qcow2'/>
        <source file='/var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.snap3'/>
        <backingStore type='file' index='3'>
          <format type='qcow2'/>
          <source file='/var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.snap2'/>
          <backingStore type='file' index='2'>
            <format type='qcow2'/>
            <source file='/var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.snap1'/>
            <backingStore type='file' index='1'>
              <format type='qcow2'/>
              <source file='/var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.qcow2'/>
              <backingStore/>
            </backingStore>
          </backingStore>
        </backingStore>
      </backingStore>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>

4. Do blockpull, failed as follow:
(.libvirt-ci-venv-ci-runtest-jUzTYn) [root@libvirt-rhel-8 ~]# virsh blockpull avocado-vt-vm1 vda --base vda[1]
error: internal error: unable to execute QEMU command 'block-stream': Node 'libvirt-1-format' is not a backing image of 'libvirt-5-format'


Expected result:
Block pull should be successful

Additional info:
libvirtd log as attachment
This may have same root cause with bz1780705