[Qemu-devel] [PATCH V3 0/9] add internal snapshot support at block device level

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

  This series brings internal snapshot support at block devices level, now we
have two three methods to do block snapshot lively: 1) backing chain,
2) internal one and 3) drive-back up approach.

Comparation:
             Advantages:                            Disadvantages:
1)    delta data, taken fast, export, size        performance, delete slow.
2)  taken fast, delete fast, performance, size       delta data, format
3)      performance, export, format               taken slow, delta data, size

  I think in most case, saving vmstate in an standalone file is better than
saving it inside qcow2, So suggest treat internal snapshot as block level
methods and not encourage user to savevm in qcow2 any more.

Implemention details:
  To avoid trouble, this serial have hide ID in create interfaces, this make
sure no chaos of ID and name will be introduced by these interfaces.
  There is one patch may be common to Pavel's savvm transaction, patch 1/11,
others are not quite related. Patch 1/11 will not set errp when no snapshot
find, since patch 3/11 need to distinguish real error case.

Next steps to better full VM snapshot:
  Improve internal snapshot's export capability.
  Better vmstate saving.

  Thanks Kevin to give advisement about how add it in qmp_transaction, oldest
version comes drom Dietmar Maurer.

v3:
  General:
  Rebased after Stenfan's driver-backup patch V6.

  Address Eric's comments:
  4/9: grammar fix and better doc.
  5/9: parameter name is mandatory now. grammar fix.
  6/9: redesiged interface: take both id and name as optional parameter, return
the deleted snapshot's info.

  Address Stefan's comments:
  4/9: add '' around %s in message. drop code comments about vm_clock.
  9/9: better doc, refined the code and add more test case.


Wenchao Xia (9):
  1 snapshot: new function bdrv_snapshot_find_by_id_and_name()
  2 snapshot: add paired functions for internal snapshot id and name
  3 snapshot: distinguish id and name in snapshot delete
  4 qmp: add internal snapshot support in qmp_transaction
  5 qmp: add interface blockdev-snapshot-internal-sync
  6 qmp: add interface blockdev-snapshot-delete-internal-sync
  7 hmp: add interface hmp_snapshot_blkdev_internal
  8 hmp: add interface hmp_snapshot_delete_blkdev_internal
  9 qemu-iotests: add 056 internal snapshot for block device test case

 block/qcow2-snapshot.c     |   68 +++++++++---
 block/qcow2.h              |    5 +-
 block/rbd.c                |   23 ++++-
 block/sheepdog.c           |    5 +-
 block/snapshot.c           |  130 +++++++++++++++++++++-
 blockdev.c                 |  191 +++++++++++++++++++++++++++++++
 hmp-commands.hx            |   37 ++++++-
 hmp.c                      |   22 ++++
 hmp.h                      |    2 +
 include/block/block_int.h  |    5 +-
 include/block/snapshot.h   |   14 ++-
 include/qemu-common.h      |    3 +
 qapi-schema.json           |   67 +++++++++++-
 qemu-img.c                 |    5 +-
 qmp-commands.hx            |  104 ++++++++++++++++-
 savevm.c                   |   10 ++-
 tests/qemu-iotests/056     |  267 ++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/056.out |    5 +
 tests/qemu-iotests/group   |    1 +
 19 files changed, 926 insertions(+), 38 deletions(-)
 create mode 100755 tests/qemu-iotests/056
 create mode 100644 tests/qemu-iotests/056.out