This is largely the same series that Vladimir sent in January, but at
the time I was unsure of if we'd want these commands or not in QEMU.

After discussing with Virtuozzo their plans for a checkpoint-like API
implemented primarily in libvirt, I agree that these commands are at
least tentatively useful.

Eric Blake is currently writing a counter-proposal and demo API to show
to Virtuozzo on libvirt's development list. Check in these QMP commands
with the experimental prefix 'x-' for now so that it can be used for
prototyping.

Once the design for the libvirt API looks reasonably final I will
remove the 'x-' prefixes, or, if we wind up not using these particular
commands I will delete them entirely.

v3:
 - Drop patch one (already merged)
 - Minor phrasing adjustments to documentation
 - Removed &state->bs argument to bitmap lookup for enable/disable
 - Added x- prefix to all three commands and to add's new argument.

Vladimir's original cover letter is below:

There are three qmp commands, needed to implement external backup API.

Using these three commands, client may do all needed bitmap management by
hand:

on backup start we need to do a transaction:
 {disable old bitmap, create new bitmap}

on backup success:
 drop old bitmap

on backup fail:
 enable old bitmap
 merge new bitmap to old bitmap
 drop new bitmap

John Snow (1):
  qapi: add x-block-dirty-bitmap-enable/disable

Vladimir Sementsov-Ogievskiy (4):
  block/dirty-bitmap: add lock to bdrv_enable/disable_dirty_bitmap
  qmp: transaction support for x-block-dirty-bitmap-enable/disable
  qapi: add x-block-dirty-bitmap-merge
  qapi: add disabled parameter to block-dirty-bitmap-add

 block/dirty-bitmap.c         |  24 ++++++-
 blockdev.c                   | 163 ++++++++++++++++++++++++++++++++++++++++++-
 include/block/dirty-bitmap.h |   3 +-
 qapi/block-core.json         |  86 ++++++++++++++++++++++-
 qapi/transaction.json        |   4 ++
 5 files changed, 275 insertions(+), 5 deletions(-)

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2.14.3