[Qemu-block] [PATCH v5 0/4] Add 'blockdev-snapshot' command

[Alberto Garcia]

This fixes the problem detect by Fam: the previous series was deleting
the 'backing' option for 'blockdev-add' even if it contained a
non-empty string.

The code is also rebased on top of the current master. In particular
the test output had to be adapted because of fe646693.

Again, this depends on Max's BlockBackend and media series:

   https://lists.gnu.org/archive/html/qemu-block/2015-07/msg00382.html

Berto

v5:
- Don't delete the 'backing' option if it contains something different
  from an empty string.
- Rebase on top of the current master.

v4: https://lists.gnu.org/archive/html/qemu-block/2015-09/msg00372.html
- Implement the support for 'backing': '', drop 'ignore-backing',
  and update iotest 085 accordingly.
- Include sample 'blockdev-add' call in the 'blockdev-snapshot'
  documentation.
- Clarify that the snapshot must not have a backing file in the
  BlockdevSnapshot documentation.
- Update error message ("...node name already existing" -> "...exists").

v3: https://lists.gnu.org/archive/html/qemu-block/2015-09/msg00272.html
- Add 'ignore-backing' field to BlockdevOptionsGenericCOWFormat. This
  allows opening images but not their backing images.
- Check for op blockers in the snapshot node and make sure that it
  doesn't have any backing image.
- Remove extra check for the existence of the snapshot node:
  bdrv_open() already does that.
- Extend iotest 085 to add tests for 'blockdev-snapshot'.
- Replace local_err with errp in some places where the former is
  unnecessary.
- Update command description.
- Add 'since' tag to the 'blockdev-snapshot' field in TransactionAction.

v2: https://lists.gnu.org/archive/html/qemu-block/2015-09/msg00094.html
- Add 'blockdev-snapshot' command instead of allowing passing options
  to 'blockdev-snapshot-sync'.
- Rename BlockdevSnapshot to BlockdevSnapshotSync

v1: https://lists.gnu.org/archive/html/qemu-block/2015-08/msg00236.html

Alberto Garcia (4):
  block: rename BlockdevSnapshot to BlockdevSnapshotSync
  block: support passing 'backing': '' to 'blockdev-add'
  block: add a 'blockdev-snapshot' QMP command
  block: add tests for the 'blockdev-snapshot' command

 block.c                    |   7 ++
 blockdev.c                 | 165 ++++++++++++++++++++++++++++-----------------
 qapi-schema.json           |   4 +-
 qapi/block-core.json       |  34 +++++++++-
 qmp-commands.hx            |  38 +++++++++++
 tests/qemu-iotests/085     | 102 ++++++++++++++++++++++++++--
 tests/qemu-iotests/085.out |  34 +++++++++-
 7 files changed, 311 insertions(+), 73 deletions(-)

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2.5.1