qemu-img snapshot would break win8.1's system disk data
Description of problem:
`qemu-img snapshot` will cause a damage on windows 8.1 virtual machine
Steps to reproduce:
1.shutdown the virtual machine

2.exec command
```
$ qemu-img snapshot -d standard /media/user/SSD_VM/disk/win8_1.qcow2
...
ERROR cluster 554329 refcount=0 reference=1
ERROR cluster 554330 refcount=0 reference=1
ERROR cluster 554331 refcount=0 reference=1
ERROR cluster 554332 refcount=0 reference=1
ERROR cluster 554333 refcount=0 reference=1
ERROR cluster 554334 refcount=0 reference=1
ERROR cluster 554335 refcount=0 reference=1
Leaked cluster 557183 refcount=2 reference=1
Leaked cluster 557472 refcount=2 reference=1
Leaked cluster 564785 refcount=2 reference=1
...
Leaked cluster 580393 refcount=2 reference=1
Leaked cluster 580434 refcount=2 reference=1
Leaked cluster 580713 refcount=2 reference=1
Leaked cluster 580718 refcount=2 reference=1
Leaked cluster 580726 refcount=2 reference=1
Leaked cluster 580965 refcount=2 reference=1
Leaked cluster 581268 refcount=2 reference=1
Leaked cluster 581280 refcount=2 reference=1
Leaked cluster 581367 refcount=2 reference=1
Leaked cluster 582743 refcount=2 reference=1
Leaked cluster 582938 refcount=2 reference=1
Leaked cluster 583026 refcount=2 reference=1
Leaked cluster 583027 refcount=2 reference=1
Leaked cluster 583028 refcount=2 reference=1
Leaked cluster 583029 refcount=2 reference=1
Rebuilding refcount structure
Repairing cluster 547917 refcount=1 reference=0
Repairing cluster 547936 refcount=1 reference=0
Repairing cluster 547955 refcount=1 reference=0
Repairing cluster 548069 refcount=1 reference=0
Repairing cluster 548092 refcount=1 reference=0
Repairing cluster 548115 refcount=1 reference=0
Repairing cluster 548125 refcount=1 reference=0
Repairing cluster 548128 refcount=1 reference=0
Repairing cluster 548130 refcount=1 reference=0
Repairing cluster 548144 refcount=1 reference=0
Repairing cluster 548146 refcount=1 reference=0
Repairing cluster 548150 refcount=1 reference=0
Repairing cluster 548199 refcount=1 reference=0
Repairing cluster 548201 refcount=1 reference=0
Repairing cluster 548226 refcount=1 reference=0
Repairing cluster 548234 refcount=1 reference=0
Repairing cluster 548236 refcount=1 reference=0
Repairing cluster 557073 refcount=1 reference=0
Repairing cluster 557074 refcount=1 reference=0
...

```

3.start the virtual machine , it shows blue screen error:
`UNEXPECTED_STORE_EXCPETION`
![Screenshot_20220828_131532](/uploads/d8c03c01deb9ae1183a4efd823850c7e/Screenshot_20220828_131532.png)
Additional information:
the windows virtual machine will automatically fix the damage that qemu-img caused on next restart .