[Qemu-devel] [Bug 1815993] [NEW] drive-backup with iscsi will cause vm disk no response

[Cheng Chen <1815993@bugs.launchpad.net>]

Public bug reported:

virsh qemu-monitor-command ${DOMAIN} '{ "execute" : "drive-backup" ,
"arguments" : { "device" : "drive-virtio-disk0" , "sync" : "top" ,
"target" : "iscsi://192.168.1.100:3260/iqn.2019-01.com.iaas/0" } }'

When the drive-backup is running, I manually crash the iscsi server（or
interrupt network, eg. iptables -j DROP）.

Then after less than 1 minute：
virsh qemu-monitor-command ${DOMAIN} --pretty '{ "execute": "query-block" }' will block and no any response, until timeout. This is still excusable.
But, the disk（drive-virtio-disk0）will occur the same situation：in vm os, the disk will block and no any response.

In other words, when qemu and iscsi-server lose contact, It will cause
the vm unable.

---
Host: centos 7.5
qemu version: ovirt-4.2（qemu-2.12.0）
qemu command line: qemu-system-x86_64 -name guest=test,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-190-test./master-key.aes -machine pc-i440fx-3.1,accel=kvm,usb=off,dump-guest-core=off,mem-merge=off -m 1024 -mem-prealloc -mem-path /dev/hugepages1G/libvirt/qemu/190-test -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 1c8611c2-a18a-4b1c-b40b-9d82040eafa4 -smbios type=1,manufacturer=IaaS -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=31,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot menu=on,strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x3 -drive file=/opt/vol/sas/fb0c7c37-13e7-41fe-b3f8-f0fbaaeec7ce,format=qcow2,if=none,id=drive-virtio-disk0,cache=writeback -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,write-cache=on -drive file=/opt/vol/sas/bde66671-536d-49cd-8b46-a4f1ea7be513,format=qcow2,if=none,id=drive-virtio-disk1,cache=writeback -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1,write-cache=on -netdev tap,fd=33,id=hostnet0,vhost=on,vhostfd=34 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:85:45:3e:d4:3a,bus=pci.0,addr=0x6 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,fd=35,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 0.0.0.0:0,password -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on

iscsi：
yum -y install targetcli python-rtslib
systemctl start target
systemctl enable target

targetcli /iscsi create iqn.2019-01.com.iaas

targetcli /iscsi/iqn.2019-01.com.iaas/tpg1 set attribute
authentication=0 demo_mode_write_protect=0 generate_node_acls=1

targetcli /iscsi/iqn.2019-01.com.iaas/tpg1/portals create 192.168.1.100 3260
targetcli /backstores/fileio create testfile1 /backup/file1 2G
targetcli /iscsi/iqn.2019-01.com.iaas/tpg1/luns create /backstores/fileio/testfile1

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1815993

Title:
  drive-backup with iscsi will cause vm disk no response

Status in QEMU:
  New

Bug description:
  virsh qemu-monitor-command ${DOMAIN} '{ "execute" : "drive-backup" ,
  "arguments" : { "device" : "drive-virtio-disk0" , "sync" : "top" ,
  "target" : "iscsi://192.168.1.100:3260/iqn.2019-01.com.iaas/0" } }'

  When the drive-backup is running, I manually crash the iscsi server（or
  interrupt network, eg. iptables -j DROP）.

  Then after less than 1 minute：
  virsh qemu-monitor-command ${DOMAIN} --pretty '{ "execute": "query-block" }' will block and no any response, until timeout. This is still excusable.
  But, the disk（drive-virtio-disk0）will occur the same situation：in vm os, the disk will block and no any response.

  In other words, when qemu and iscsi-server lose contact, It will cause
  the vm unable.

  ---
  Host: centos 7.5
  qemu version: ovirt-4.2（qemu-2.12.0）
  qemu command line: qemu-system-x86_64 -name guest=test,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-190-test./master-key.aes -machine pc-i440fx-3.1,accel=kvm,usb=off,dump-guest-core=off,mem-merge=off -m 1024 -mem-prealloc -mem-path /dev/hugepages1G/libvirt/qemu/190-test -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 1c8611c2-a18a-4b1c-b40b-9d82040eafa4 -smbios type=1,manufacturer=IaaS -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=31,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot menu=on,strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x3 -drive file=/opt/vol/sas/fb0c7c37-13e7-41fe-b3f8-f0fbaaeec7ce,format=qcow2,if=none,id=drive-virtio-disk0,cache=writeback -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,write-cache=on -drive file=/opt/vol/sas/bde66671-536d-49cd-8b46-a4f1ea7be513,format=qcow2,if=none,id=drive-virtio-disk1,cache=writeback -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1,write-cache=on -netdev tap,fd=33,id=hostnet0,vhost=on,vhostfd=34 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:85:45:3e:d4:3a,bus=pci.0,addr=0x6 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,fd=35,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 0.0.0.0:0,password -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on

  iscsi：
  yum -y install targetcli python-rtslib
  systemctl start target
  systemctl enable target

  targetcli /iscsi create iqn.2019-01.com.iaas

  targetcli /iscsi/iqn.2019-01.com.iaas/tpg1 set attribute
  authentication=0 demo_mode_write_protect=0 generate_node_acls=1

  targetcli /iscsi/iqn.2019-01.com.iaas/tpg1/portals create 192.168.1.100 3260
  targetcli /backstores/fileio create testfile1 /backup/file1 2G
  targetcli /iscsi/iqn.2019-01.com.iaas/tpg1/luns create /backstores/fileio/testfile1

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