live migration with storage encounter assert(!(bs->open_flags & BDRV_O_INACTIVE)) crashes

The vm guest runs a iotest program, and i migrate it with virsh --copy-storage-all,then the qemu process on the source host happens to crash with the following message:

kvm: block/io.c:1543: bdrv_co_pwritev: Assertion `!(bs->open_flags & 0x0800)' failed.
2017-08-24 11:43:45.919+0000: shutting down, reason=crashed


here is the release:
qemu 2.7 & 2.10.rc3 were tested.
libvirt 3.0.0 & 3.2.0 were tested.

command line:
src_host:virsh migrate --verbose --live --persistent --copy-storage-all vm-core qemu+ssh://dst_host/system

Resaon: After bdrv_inactivate_all() was called, mirror_run coroutine stills write the left dirty disk data to remote nbd server, which triggers the assertion. But I don't known how to avoid the problem, help is needed!  Thanks.