Bug 1090374

+++ This bug was initially created as a clone of Bug #1032393 +++
+++ This bug was initially created as a clone of Bug #1032369 +++

Description of problem:
fail to boot guest with pass-through iSCSI LUN specified '-snapshot/snapshot=on'.
But we can create snapshot from a pass-through iSCSI LUN to local file successfully.

Version-Release number of selected component (if applicable):
host info:
3.10.0-50.el7.x86_64
qemu-kvm-rhev-1.5.3-19.el7.x86_64
seabios-1.7.2.2-4.el7.x86_64
guest info:
2.6.32-425.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.boot guest with pass-through iSCSI LUN specified '-snapshot/snapshot=on'. 
e.g:/usr/libexec/qemu-kvm -M q35 -S -cpu SandyBridge -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -no-kvm-pit-reinjection...-drive file=/dev/disk/by-path/ip-10.66.90.100:3260-iscsi-iqn.2001-05.com.equallogic:0-8a0906-0971f7d03-1dff49b26885073d-s2-sluo-172259-lun-0,if=none,id=drive-data-disk,format=raw,cache=none,aio=native,werror=stop,rerror=stop,snapshot=on -device virtio-scsi-pci,bus=pcie.0,addr=0x7,id=scsi0 -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0
2.
3.

Actual results:
after step 1, QEMU will quit with wrong warning message.
(qemu) qemu-kvm: -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0: scsi-block: scsi generic interface too old
qemu-kvm: -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0: Device initialization failed.
qemu-kvm: -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0: Device 'scsi-block' could not be initialized

Expected results:
It should boot up guest successfully with pass-through iSCSI LUN specified '-snapshot/snapshot=on'. 

Additional info:
# /usr/libexec/qemu-kvm -M q35 -S -cpu SandyBridge -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -no-kvm-pit-reinjection -usb -device usb-tablet,id=input0 -name sluo -uuid 990ea161-6b67-47b2-b803-19fb01d30d10 -rtc base=localtime,clock=host,driftfix=slew -device virtio-serial-pci,id=virtio-serial0,max_ports=16,vectors=0,bus=pcie.0,addr=0x3 -chardev socket,id=channel1,path=/tmp/helloworld1,server,nowait -device virtserialport,chardev=channel1,name=com.redhat.rhevm.vdsm,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 -drive file=/home/RHEL6.5-20131019.1_Server_x86_64.qcow2bk,if=none,id=drive-virtio-disk,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,vectors=0,bus=pcie.0,addr=0x4,scsi=off,drive=drive-virtio-disk,id=virtio-disk,bootindex=1 -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device rtl8139,netdev=hostnet0,id=virtio-net-pci0,mac=00:01:02:03:04:05,bus=pcie.0,addr=0x5 -device virtio-balloon-pci,id=ballooning,bus=pcie.0,addr=0x6 -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0 -drive file=/dev/disk/by-path/ip-10.66.90.100:3260-iscsi-iqn.2001-05.com.equallogic:0-8a0906-0971f7d03-1dff49b26885073d-s2-sluo-172259-lun-0,if=none,id=drive-data-disk,format=raw,cache=none,aio=native,werror=stop,rerror=stop,snapshot=on -device virtio-scsi-pci,bus=pcie.0,addr=0x7,id=scsi0 -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0 -k en-us -boot menu=on -qmp tcp:0:4444,server,nowait -serial unix:/tmp/ttyS0,server,nowait -vnc :1 -spice disable-ticketing,port=5931 -monitor stdio