On Mon, Jan 27, 2014 at 11:48:06AM +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 > > (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 > > v11 -> v12: Rebase to qemu.git. > Call bdrv_refresh_limits() in bdrv_set_backing_hd(). > > v8 -> v11: Rebased to qemu.git. Address Stefan's comments: > (sorry for sending 3 revisions in a day) > > [01/11] block: Add BlockOpType enum > Change enum definition as internal. > > [05/11] block: Add bdrv_set_backing_hd() > Set bs->backing_file and bs->backing_format. > > [06/11] block: Add backing_blocker in BlockDriverState > Reuse bdrv_set_backing_hd(). > > [07/11] block: Parse "backing" option to reference existing BDS > Update commit message about bdrv_swap assertion removal. > Fix use-after-free. > Check for "backing=" and "backing.file=" conflict. > > [08/11] block: Support dropping active in bdrv_drop_intermediate > Fix function comment. > > [09/11] stream: Use bdrv_drop_intermediate and drop close_unused_images > > > Fam Zheng (11): > 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-migration.c | 7 +- > block.c | 310 > ++++++++++++++++++++++++++-------------- > block/backup.c | 21 +++ > block/commit.c | 1 + > block/stream.c | 30 +--- > blockdev.c | 70 +++++++-- > 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 | 49 +++++++ > qmp-commands.hx | 44 ++++++ > 13 files changed, 446 insertions(+), 160 deletions(-)
I had only one comment on the code, see my reply. But we need tests in order to merge this. Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
