Description of problem:
During VM installation, migrate from src to dst, before migration finishes, qemu runs into ENOSPAC in src host, installation continues after enlarging the image by 1G, issue 'info migrate' in src monitor, it shows migration failed, launch dst qemu-kvm again, run into ENOSPAC second time in src qemu-kvm when migrating from src to dst again, enlarge image by 20G, issue 'c' and this time qemu claims migration completed but dst qemu-kvm still in paused status and if issue 'c', qemu will claim 'No space left on device (28)'. In fact, image is already more than 20G.

Version-Release number of selected component (if applicable):
# rpm -qa|grep qemu-kvm
qemu-kvm-debuginfo-0.12.1.2-2.148.el6.x86_64
qemu-kvm-0.12.1.2-2.148.el6.x86_64
qemu-kvm-tools-0.12.1.2-2.148.el6.x86_64

# uname -r
2.6.32-118.el6.x86_64

CLI:
# /usr/libexec/qemu-kvm -M rhel6.1.0 -enable-kvm -m 4096 -smp 2 -cpu cpu64-rhel6 -name rhel -uuid `uuidgen` -rtc base=localtime,clock=vm,driftfix=slew -no-kvm-pit-reinjection -boot dc -drive file=/dev/s2/test-enospac,if=none,id=drive-ide0-0-0,media=disk,format=qcow2,cache=none,werror=stop,rerror=stop -device ide-drive,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,id=hostnet1,vhost=on -device rtl8139,netdev=hostnet1,id=net1,mac=52:54:40:11:67:13 -usb -device usb-tablet,id=input1 -spice port=8800,disable-ticketing -vga qxl -monitor stdio -balloon none -cdrom /mnt/image/Windows_Server_2008_R2_GA_EN.iso -incoming tcp:0:5890



How reproducible:
2/2

Steps to Reproduce:
1. 
1.1 On a src host, create a 512m size space
# lvcreate -n test-enospac -L 512m s2
issue lvscan on dst host,
1.2 On dst host, issue
# lvscan
ACTIVE            '/dev/s2/test-enospac' [512.00 MiB] inherit
1.3 create an image in src host:
# qemu-img create -f qcow2 test-enospac 20G
Formatting 'test-enospac', fmt=qcow2 size=21474836480 encryption=off cluster_size=0 

2. Install guest in src host and hit ENOSPAC
(qemu) info status 
VM status: running
(qemu) block I/O error in device 'drive-ide0-0-0': No space left on device (28)
handle_dev_input: stop

3. 
3.1 Extend image by 2G in src host 
# lvextend -L +2G /dev/s2/test-enospac 
  Found duplicate PV L2iTsxVknfTDmPqMGPXo0ujp6uomRePl: using /dev/sdc not /dev/sdb
  Extending logical volume test-enospac to 2.50 GiB
  Logical volume test-enospac successfully resized
3.2 Issue lvscan in dst host:
ACTIVE            '/dev/s2/test-enospac' [2.50 GiB] inherit
3.3 issue cont in src monitor, continue installation
(qemu) c
handle_dev_input: start

4. Do migration from src to dst
(qemu) migrate -d tcp:xxxx:5880
(qemu) info migrate 
Migration status: active
transferred ram: 116872 kbytes
remaining ram: 4208988 kbytes
total ram: 4325768 kbytes
5. During migration, hit ENOSPAC again, then enlarge image by 15G in src host and run lvscan in dst host.
(qemu) info migrate 
Migration status: active
transferred ram: 2456208 kbytes
remaining ram: 2397944 kbytes
total ram: 4325768 kbytes
(qemu) block I/O error in device 'drive-ide0-0-0': No space left on device (28)
handle_dev_input: stop

# lvextend -L +15G /dev/s2/test-enospac 
  Found duplicate PV L2iTsxVknfTDmPqMGPXo0ujp6uomRePl: using /dev/sdc not /dev/sdb
  Extending logical volume test-enospac to 17.50 GiB
  Logical volume test-enospac successfully resized

# lvscan
  Found duplicate PV L2iTsxVknfTDmPqMGPXo0ujp6uomRePl: using /dev/sdc not /dev/sdb

  ACTIVE            '/dev/s2/test-enospac' [17.50 GiB] inherit
6. Issue c in monitor, info migration, qemu claims migration completed, but in dst host, qemu claims that qemu is paused instead of running.

***In src host***:
(qemu) info migrate 
Migration status: active
transferred ram: 2456208 kbytes
remaining ram: 2397944 kbytes
total ram: 4325768 kbytes
(qemu) block I/O error in device 'drive-ide0-0-0': No space left on device (28)
handle_dev_input: stop

(qemu) c
handle_dev_input: start
(qemu) info migrate 
Migration status: completed

***In dst host***
(qemu) handle_dev_destroy_surfaces: 
handle_dev_input: start
block I/O error in device 'drive-ide0-0-0': No space left on device (28)
handle_dev_input: stop

(qemu) info status 
VM status: paused
(qemu) 

7. Issue cont in dst monitor, we get:
(qemu) c
handle_dev_input: start
(qemu) block I/O error in device 'drive-ide0-0-0': No space left on device (28)
handle_dev_input: stop

  
Actual results:
qemu-kvm in dst host ignores the enlarged size, still claims ENOSPAC. In fact, the image is already 17.5Gb.

Expected results:
qemu-kvm in dst host can finish installation without claiming ENOSPAC which does not exist actually.

Additional info:
Please **note**, after step 7 above, if I extend the image again in dst host, then issue c in monitor, installation can be continued, but qcow2 image was corrupted.
(qemu) block I/O error in device 'drive-ide0-0-0': No space left on device (28)
handle_dev_input: stop

(qemu) c
handle_dev_input: start
(qemu) spice_server_add_interface: SPICE_INTERFACE_TABLET

(qemu) info status 
VM status: running
(qemu) 

# qemu-img check /dev/s2/test-enospac
...
ERROR cluster 96880 refcount=0 reference=1
ERROR cluster 96881 refcount=0 reference=1
ERROR cluster 96882 refcount=0 reference=1
ERROR cluster 96883 refcount=0 reference=1
ERROR cluster 96884 refcount=0 reference=1
ERROR cluster 96885 refcount=0 reference=1
ERROR cluster 96886 refcount=0 reference=1
ERROR cluster 96887 refcount=0 reference=1
ERROR cluster 96888 refcount=0 reference=1
ERROR cluster 96889 refcount=0 reference=1
ERROR cluster 96890 refcount=0 reference=1
...
764 errors were found on the image.
Data may be corrupted, or further writes to the image may corrupt it.

13070 leaked clusters were found on the image.
This means waste of disk space, but no harm to data.