commit snapshot image got Permission denied error

qemu 2.9.0, adm64, start image with -snapshot param, make some changes in the image, then:

$telnet localhost 7000

(qemu) commit virtio0
'commit' error for 'virtio0': Permission denied

Nerver met this problem before, commit is ok. I recently compiled v2.9.0, so is there some new param in qemu-qemu-system-x86_64 to avoid commit Permission denied?

Regards.

only the winxp guest image get this error, linux guest do not.

v2.9.0 must start the image with full path can commit the snapshot changes, <v2.3 no need to.

close this report.

Closing, according to comment #2