On 9/25/18 9:13 AM, Alberto Garcia wrote:
If you only want to copy parts of a backing file I think it's much
simpler if you use copy-on-read:
qemu-io -C -c 'read 0 1M' img.003.commit.000
Oh, slick.
$ qemu-img convert -O qcow2 \
"json:{'driver':'null-co','size':1048576}" \
"json:{'driver':'raw','offset':1048576,'size':2097152,\
'file':{'driver':'qcow2',\
'file':{'driver':'file','filename':'img.003'}}}" \
img.003.nocommit
qemu-io -C -c 'read 1M 1M' img.003.nocommit
So use copy-on-read to extract the portions you care about into
temporary files, then commit those temporary files into the target.
Beats my hacks using 'qemu-nbd -c /dev/nbdN' and then several dd
processes as directed by 'qemu-img map --output=json' output.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
