[PATCH RFC C0/2] support allocation-map for block-dirty-bitmap-merge

[Vladimir Sementsov-Ogievskiy]

Hi all!

It's a simpler alternative for
"[PATCH v4 0/5] block: add block-dirty-bitmap-populate job"
  <20200902181831.2570048-1-eblake@redhat.com>
  https://lists.gnu.org/archive/html/qemu-devel/2020-09/msg00978.html
  https://patchew.org/QEMU/20200902181831.2570048-1-eblake@redhat.com/

Since we have "coroutine: true" feature for qmp commands, I think,
maybe we can merge allocation status to bitmap without bothering with
new block-job?

It's an RFC:

1. Main question: is it OK as a simple blocking command, even in a
coroutine mode. It's a lot simpler, and it can be simply used in a
transaction with other bitmap commands.

2. Transaction support is not here now. Will add in future version, if
general approach is OK.

3. I just do bdrv_co_enter() / bdrv_co_leave() like it is done in the
only coroutine qmp command - block_resize(). I'm not sure how much is it
correct.

4. I don't do any "drain". I think it's not needed, as intended usage
is to merge block-status to _active_ bitmap. So all concurrent
operations will just increase dirtyness of the bitmap and it is OK.

5. Probably we still need to create some BdrvChild to avoid node resize
during the loop of block-status querying.

6. Test is mostly copied from parallels-read-bitmap, I'll refactor it in
next version to avoid copy-paste.

7. Probably patch 01 is better be split into 2-3 patches.

Vladimir Sementsov-Ogievskiy (2):
  qapi: block-dirty-bitmap-merge: support allocation maps
  iotests: add allocation-map-to-bitmap

 qapi/block-core.json                          | 31 ++++++++-
 include/block/block_int.h                     |  4 ++
 block/dirty-bitmap.c                          | 42 ++++++++++++
 block/monitor/bitmap-qmp-cmds.c               | 55 +++++++++++++---
 .../tests/allocation-map-to-bitmap            | 64 +++++++++++++++++++
 .../tests/allocation-map-to-bitmap.out        |  9 +++
 6 files changed, 195 insertions(+), 10 deletions(-)
 create mode 100755 tests/qemu-iotests/tests/allocation-map-to-bitmap
 create mode 100644 tests/qemu-iotests/tests/allocation-map-to-bitmap.out

-- 
2.29.2