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: Address comments from Markus, Kevin and Ian. Thanks for the review!
Cover letter fixed "block-job-cancel". (Ian)
Dropped "[v7 07/10] block: Pass error in bdrv_snapshot_create". (Markus)
Dropped "[v7 08/10] block: Add checks of blocker in block operations".
(Markus)
They are neither necessary for this series nor significant improvements.
[01/10] qapi: Add BlockOperationType enum
Since 2.0. (Kevin, Markus)
[02/10] block: Introduce op_blockers to BlockDriverState
Commit message reword. (Markus)
Move bdrv_op_blocker_is_empty() here.
[03/10] block: Replace in_use with operation blocker
Moved to the front of series.
Reword commit message. (Markus)
Move memcpy in bdrv_move_feature_fields() into 02/10. (Markus)
Don't drop in_use asserts, convert them. (Markus)
Drop unused local_err. (Markus)
Simplify bdrv_op_blocker_is_empty(). (Markus)
Fix error message for do_drive_del() and dataplane. (Markus)
Remember to error_free for dataplane op blocker. (Markus)
Drop whitespace change. (Markus)
Mechanical convert of in_use for block_job_create().
[04/10] block: Add bdrv_set_backing_hd()
New. Separate the common part for setting backing_hd.
[05/10] block: Add backing_blocker in BlockDriverState
New.
[06/10] block: Parse "backing" option to reference existing BDS
Make use of 04/10.
We need to delete "backing" from qdict, otherwise QMP complains
with an supported option, not dropping it. (Markus)
Move error_free(bs->backing_blocker) in bdrv_close(). (Markus)
Reword comment for backing_blocker. (Markus)
03/10 retained the logic of in_use assert, this is no longer true
since backing_hd has a blocker on it. So drop it. (Markus)
[07/10] block: Support dropping active in bdrv_drop_intermediate
Make use of 04/10. (Kevin)
Pass NULL, NULL instead of empty string to
bdrv_change_backing_file. (Kevin)
[08/10] stream: Use bdrv_drop_intermediate and drop close_unused_images
[09/10] qmp: Add command 'blockdev-backup'
Since 1.8 -> Since 2.0.
[10/10] block: Allow backup on referenced named BlockDriverState
v7: Fix typo in cover letter "ide0-hd0". (Markus)
Rebase to current qemu.git. (Resolved a few trivial contextual conflict)
v6: Address Paolo's comments, (except for bitmask):
- Add blocker for all backing_hd references, a relatively big change, some
patches are reordered.
- Introduce a few other necessary patches.
- Move two snapshot checks into bdrv_snapshot_*.
The interface is unchanged.
Fam Zheng (12):
blkdebug: Use QLIST_FOREACH_SAFE to resume IO
qapi: Add BlockOperationType 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 | 291 ++++++++++++++++++++++++++--------------
block/backup.c | 21 +++
block/blkdebug.c | 8 +-
block/commit.c | 1 +
block/stream.c | 28 +---
blockdev.c | 70 ++++++++--
blockjob.c | 14 +-
hw/block/dataplane/virtio-blk.c | 18 ++-
include/block/block.h | 10 +-
include/block/block_int.h | 9 +-
include/block/blockjob.h | 3 +
qapi-schema.json | 99 ++++++++++++++
qmp-commands.hx | 44 ++++++
14 files changed, 465 insertions(+), 158 deletions(-)
--
1.8.5.1
