Red Hat Bugzilla – Bug 1140001
data-plane hotplug should be refused to start if device is already in use (drive-mirror job)
Last modified: 2015-08-06 03:44:32 EDT
Description of problem: QEMU should print an error message and refuse to hotplug with virtio-blk data-plane while the drive-mirror job is running, this can prevent data corruption according to bug 995530. Version-Release number of selected component (if applicable): host info: # uname -r && rpm -q qemu-kvm-rhev 3.10.0-152.el7.x86_64 qemu-kvm-rhev-2.1.0-3.el7.x86_64 guest info: # uname -r 3.10.0-152.el7.x86_64 How reproducible: 100% Steps to Reproduce: 1.start QEMU with "-drive file=/home/RHEL-7.0-20140507.0-Server-x86_64.qcow2,if=none,id=drive-system-disk0,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop" 2.the guest will be at the BIOS screen because there is no virtio-blk-pci device yet. Then start a drive-mirror operation on the QMP monitor: { "execute": "drive-mirror", "arguments": { "device": "drive-system-disk0", "target": "/root/sn1", "format": "qcow2", "mode": "absolute-paths", "sync": "full", "speed": 1000000000, "on-target-error": "stop" } } 3.do hotplug virtio-blk data-plane device. {"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"drive-system-disk0","id":"system-disk0","iothread":"iothread0"}} 4.do system_rest to start KVM guest. Actual results: 1.step 2 and step 3 QMP commands execute successfully, while the QEMU HMP monitor prompt a "cannot start dataplane thread: Device 'drive-system-disk0' is busy: block device is in use by block job: mirror" message. { "execute": "drive-mirror", "arguments": { "device": "drive-system-disk0", "target": "/root/sn1", "format": "qcow2", "mode": "absolute-paths", "sync": "full", "speed": 1000000000, "on-target-error": "stop" } } {"return": {}} { "execute" : "query-block-jobs", "arguments" : {} } {"return": [{"io-status": "ok", "device": "drive-system-disk0", "busy": true, "len": 10737418240, "offset": 3931963392, "paused": false, "speed": 1000000000, "type": "mirror"}]} {"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"drive-system-disk0","id":"system-disk0","iothread":"iothread0"}} {"return": {}} (qemu) Formatting '/root/sn1', fmt=qcow2 size=10737418240 encryption=off cluster_size=65536 lazy_refcounts=off cannot start dataplane thread: Device 'drive-system-disk0' is busy: block device is in use by block job: mirror 2.after step 4, guest boot up successfully. { "execute": "system_reset" } {"return": {}} Expected results: QEMU should print an error message and refuse to hotplug with virtio-blk data-plane while the drive-mirror job is running, this can prevent data corruption. So, step 3 should not hotplug successfully and step 4 guest should not boot up successfully. Additional info:
my whole qemu-kvm command line: # /usr/libexec/qemu-kvm -M pc -S -cpu SandyBridge -enable-kvm -m 2048 -smp 4,sockets=2,cores=2,threads=1 -no-kvm-pit-reinjection -usb -device usb-tablet,id=input0 -name sluo -uuid 990ea161-6b67-47b2-b803-19fb01d30d30 -rtc base=localtime,clock=host,driftfix=slew -device virtio-serial-pci,id=virtio-serial0,max_ports=16,vectors=0,bus=pci.0,addr=0x3 -chardev socket,id=channel1,path=/tmp/helloworld1,server,nowait -device virtserialport,chardev=channel1,name=com.redhat.rhevm.vdsm1,bus=virtio-serial0.0,id=port1 -chardev socket,id=channel2,path=/tmp/helloworld2,server,nowait -device virtserialport,chardev=channel2,name=com.redhat.rhevm.vdsm,bus=virtio-serial0.0,id=port2 -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=virtio-net-pci0,mac=00:01:02:B6:40:21,bus=pci.0,addr=0x5 -device virtio-balloon-pci,id=ballooning,bus=pci.0,addr=0x6 -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0 -k en-us -boot menu=on -qmp tcp:0:4444,server,nowait -serial unix:/tmp/ttyS0,server,nowait -spice disable-ticketing,port=5931 -vga qxl -global qxl-vga.vram_size=33554432 -monitor stdio -object iothread,id=iothread0 -drive file=/home/RHEL-7.0-20140507.0-Server-x86_64.qcow2,if=none,id=drive-system-disk0,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop Best Regards, sluo
Thanks, there was a regression upstream and I have submitted a patch: [PATCH] dataplane: fix virtio_blk_data_plane_create() op blocker error path Once it has been merged I will backport it.
The backport has been posted.
Fix included in qemu-kvm-rhev-2.1.2-4.el7
verify this issue on qemu-kvm-rhev-2.1.2-5.el7.x86_64. host info: # uname -r && rpm -q qemu-kvm-rhev 3.10.0-191.el7.x86_64 qemu-kvm-rhev-2.1.2-5.el7.x86_64 e.g:...-object iothread,id=iothread0 -drive file=/home/rhel7-desktop-64.qcow2,if=none,id=drive-system-disk0,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop {"execute":"qmp_capabilities"} {"return": {}} { "execute": "drive-mirror", "arguments": { "device": "drive-system-disk0", "target": "/root/sn1", "format": "qcow2", "mode": "absolute-paths", "sync": "full", "speed": 1000000000, "on-target-error": "stop" } } {"return": {}} {"execute":"device_add","arguments":{"driver":"virtio-blk-pci","drive":"drive-system-disk0","id":"system-disk0","iothread":"iothread0"}} {"error": {"class": "GenericError", "desc": "cannot start dataplane thread: Device 'drive-system-disk0' is busy: block device is in use by block job: mirror"}} Base on above, this issue has been fixed correctly, move to VERIFIED status. Best Regards, sluo
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHSA-2015-0624.html