Re: [PATCH 1/2] qapi: block-dirty-bitmap-merge: support allocation maps

[Vladimir Sementsov-Ogievskiy]

27.04.2021 14:11, Vladimir Sementsov-Ogievskiy wrote:

Add possibility to merge allocation map of specified node into target
bitmap.

Signed-off-by: Vladimir Sementsov-Ogievskiy<vsement...@virtuozzo.com>
---
  qapi/block-core.json            | 31 +++++++++++++++++--
  include/block/block_int.h       |  4 +++
  block/dirty-bitmap.c            | 42 +++++++++++++++++++++++++
  block/monitor/bitmap-qmp-cmds.c | 55 ++++++++++++++++++++++++++++-----
  4 files changed, 122 insertions(+), 10 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 6d227924d0..0fafb043bc 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2006,6 +2006,32 @@
    'data': { 'node': 'str', 'name': 'str', '*granularity': 'uint32',
              '*persistent': 'bool', '*disabled': 'bool' } }

+##

+# @AllocationMapMode:
+#
+# An enumeration of possible allocation maps that could be merged into target
+# bitmap.
+#
+# @top: The allocation status of the top layer of the attached storage node.
+#
+# Since: 6.1
+##
+{ 'enum': 'AllocationMapMode',
+  'data': ['top'] }
+
+##
+# @BlockDirtyBitmapMergeExternalSource:
+#
+# @node: name of device/node which the bitmap is tracking
+#
+# @name: name of the dirty bitmap
+#
+# Since: 6.1
+##
+{ 'struct': 'BlockDirtyBitmapMergeExternalSource',
+  'data': { 'node': 'str', '*name': 'str',
+            '*allocation-map': 'AllocationMapMode' } }
+
  ##
  # @BlockDirtyBitmapMergeSource:
  #
@@ -2017,7 +2043,7 @@
  ##
  { 'alternate': 'BlockDirtyBitmapMergeSource',
    'data': { 'local': 'str',
-            'external': 'BlockDirtyBitmap' } }
+            'external': 'BlockDirtyBitmapMergeExternalSource' } }

##

  # @BlockDirtyBitmapMerge:
@@ -2176,7 +2202,8 @@
  #
  ##
  { 'command': 'block-dirty-bitmap-merge',
-  'data': 'BlockDirtyBitmapMerge' }
+  'data': 'BlockDirtyBitmapMerge',
+  'coroutine': true }

##

So, what I propose makes possible to issue the following command:

block-dirty-bitmap-merge
  bitmaps: [{"allocation-map": "top", "node": "drive0"}]
  node: target-node-name
  target: target-bitmap-name


I've discussed it with Nikolay, and he requested a possibility of querying 
allocation status of base..top sub-chain (assume several snapshots was done 
without creating bitmaps, and we want to restore the bitmap for backup).

So, we actually want something like

block-dirty-bitmap-merge
  bitmaps: [{top: "tpp-node-name", bottom: "bottom-node-name"}]
  node: target-node-name
  target: target-bitmap-name


--
Best regards,
Vladimir