On Wed, Jan 29, 2014 at 01:07:27PM +0800, Fam Zheng wrote: > This series adds for point-in-time snapshot NBD exporting based on > blockdev-backup (variant of drive-backup with existing device as target). > > We get a thin point-in-time snapshot by COW mechanism of drive-backup, and > export it through built in NBD server. The steps are as below: > > 1. (SHELL) qemu-img create -f qcow2 BACKUP.qcow2 <source size here> > > (Alternatively we can use -o backing_file=RUNNING-VM.img to omit > explicitly > providing the size by ourselves, but it's risky because RUNNING-VM.qcow2 > is > used r/w by guest. Whether or not setting backing file in the image file > doesn't matter, as we are going to override the backing hd in the next > step) > > 2. (QMP) blockdev-add backing=source-drive file.driver=file > file.filename=BACKUP.qcow2 id=target0 if=none driver=qcow2
It seems like we have a regression here. I sent you a private email earlier and after some more testing I am finding that the setup that I had to test this before is no longer working. Now when I try to use blockdev-add I get: rsp = srv.cmd(command, {'options': { 'backing': 'ide0-hd0', 'driver': 'qcow2', 'id': 'target0', 'file': { 'driver': 'file', 'filename': '/home/imain/tmp/BACKUP.qcow2' } } }) rsp is {u'error': {u'class': u'GenericError', u'desc': u"could not open disk image target0: Block format 'qcow2' used by device 'target0' doesn't support the option 'backing'"}} It's possible I'm messing something up but I'm pretty sure something has changed with the options handling in bdrv_open() to make this not work anymore. Thanks! Ian > (where source-drive is the running BlockDriverState name for > RUNNING-VM.img. This patch implements "backing=" option to override > backing_hd for added drive) > > 3. (QMP) blockdev-backup device=source-drive sync=none target=target0 > > (this is the QMP command introduced by this series, which use a named > device as target of drive-backup) > > 4. (QMP) nbd-server-add device=target0 > > When image fleecing done: > > 1. (QMP) block-job-cancel device=source-drive > > 2. (HMP) drive_del target0 > > 3. (SHELL) rm BACKUP.qcow2 > > v12 -> v13: Address comments from Stefan. > > [05/15] block: Add bdrv_set_backing_hd() > Remove duplicated assignments. > > [10/15] qmp: Add command 'blockdev-backup' > Add check for source == target. > > [13/15] block: Add blockdev-backup to transaction > New. > > [14/15] qemu-iotests: Test blockdev-backup in 055 > New. > > [15/15] qemu-iotests: Image fleecing test case 081 > New. Hope this number has no conflict. I have a 080 on my > iothrottling test branch. > > v11 -> v12: Rebase to qemu.git. > Call bdrv_refresh_limits() in bdrv_set_backing_hd(). > > > > Fam Zheng (14): > block: Add BlockOpType enum > block: Introduce op_blockers to BlockDriverState > block: Replace in_use with operation blocker > block: Move op_blocker check from block_job_create to its caller > block: Add bdrv_set_backing_hd() > block: Add backing_blocker in BlockDriverState > block: Parse "backing" option to reference existing BDS > block: Support dropping active in bdrv_drop_intermediate > stream: Use bdrv_drop_intermediate and drop close_unused_images > qmp: Add command 'blockdev-backup' > block: Allow backup on referenced named BlockDriverState > block: Add blockdev-backup to transaction > qemu-iotests: Test blockdev-backup in 055 > qemu-iotests: Image fleecing test case 081 > > block-migration.c | 7 +- > block.c | 306 > ++++++++++++++++++++++++++-------------- > block/backup.c | 26 ++++ > block/commit.c | 1 + > block/stream.c | 30 +--- > blockdev.c | 118 ++++++++++++++-- > blockjob.c | 14 +- > hw/block/dataplane/virtio-blk.c | 19 ++- > include/block/block.h | 29 +++- > include/block/block_int.h | 9 +- > include/block/blockjob.h | 3 + > qapi-schema.json | 50 +++++++ > qmp-commands.hx | 44 ++++++ > tests/qemu-iotests/055 | 275 ++++++++++++++++++++++++++++++------ > tests/qemu-iotests/055.out | 4 +- > tests/qemu-iotests/081 | 99 +++++++++++++ > tests/qemu-iotests/081.out | 5 + > tests/qemu-iotests/group | 1 + > 18 files changed, 836 insertions(+), 204 deletions(-) > create mode 100755 tests/qemu-iotests/081 > create mode 100644 tests/qemu-iotests/081.out > > -- > 1.8.5.3 >