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
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 | 304 +++++++++++++++++++++++++++-------------
block/backup.c | 21 +++
block/commit.c | 1 +
block/stream.c | 28 +---
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, 444 insertions(+), 154 deletions(-)
--
1.8.5.1
