On 02.10.24 17:41, Vladimir Sementsov-Ogievskiy wrote:
On 26.06.24 14:53, Vladimir Sementsov-Ogievskiy wrote:
diff --git a/qapi/block-core.json b/qapi/block-core.json
index df5e07debd..0a6f08a6e0 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -6148,3 +6148,91 @@
##
{ 'struct': 'DummyBlockCoreForceArrays',
'data': { 'unused-block-graph-info': ['BlockGraphInfo'] } }
+
+##
+# @BlockParentType:
+#
+# @qdev: block device, such as created by device_add, and denoted by
+# qdev-id
+#
+# @driver: block driver node, such as created by blockdev-add, and
+# denoted by node-name
+#
+# @export: block export, such created by block-export-add, and
+# denoted by export-id
+#
+# Since 9.1
+##
+{ 'enum': 'BlockParentType',
+ 'data': ['qdev', 'driver', 'export'] }
+
+##
+# @BdrvChildRefQdev:
+#
+# @qdev-id: the device's ID or QOM path
+#
+# Since 9.1
+##
+{ 'struct': 'BdrvChildRefQdev',
+ 'data': { 'qdev-id': 'str' } }
+
+##
+# @BdrvChildRefExport:
+#
+# @export-id: block export identifier
+#
+# Since 9.1
+##
+{ 'struct': 'BdrvChildRefExport',
+ 'data': { 'export-id': 'str' } }
+
+##
+# @BdrvChildRefDriver:
+#
+# @node-name: the node name of the parent block node
+#
+# @child: name of the child to be replaced, like "file" or "backing"
+#
+# Since 9.1
+##
+{ 'struct': 'BdrvChildRefDriver',
+ 'data': { 'node-name': 'str', 'child': 'str' } }
+
+##
+# @BlockdevReplace:
+#
+# @parent-type: type of the parent, which child is to be replaced
+#
+# @new-child: new child for replacement
+#
+# Since 9.1
+##
+{ 'union': 'BlockdevReplace',
+ 'base': {
+ 'parent-type': 'BlockParentType',
+ 'new-child': 'str'
+ },
+ 'discriminator': 'parent-type',
+ 'data': {
+ 'qdev': 'BdrvChildRefQdev',
+ 'export': 'BdrvChildRefExport',
+ 'driver': 'BdrvChildRefDriver'
+ } }
+
+##
+# @blockdev-replace:
+#
+# Replace a block-node associated with device (selected by
+# @qdev-id) or with block-export (selected by @export-id) or
+# any child of block-node (selected by @node-name and @child)
+# with @new-child block-node.
+#
+# Features:
+#
+# @unstable: This command is experimental.
+#
+# Since 9.1
+##
+{ 'command': 'blockdev-replace', 'boxed': true,
+ 'features': [ 'unstable' ],
+ 'data': 'BlockdevReplace' }
Looking back at this all, I now have another idea: instead of trying to unite
different types of parents, maybe just publish concept of BdrvChild to QAPI? So
that it will have unique id. Like for block-nodes, it could be auto-generated
or specified by user.
Then we'll add parameters for commands:
device-add
root-child-slot-id: ID
block-export-add
block-child-slot-id: ID
and for block-drivers we already have BlockdevRef structure, it only lacks an
id.
{ 'alternate': 'BlockdevRef',
'data': { 'definition': 'BlockdevOptions',
'reference': 'str' } }
hmm.. Could it be as simple as
{ 'alternate': 'BlockdevRef',
'base': { '*child-slot-id': 'str' },
'data': { 'definition': 'BlockdevOptions',
'reference': 'str' } }
?
Oops that was obviously impossible idea :) Then, I think the only way is to introduce
virtual "reference" BlockdevDriver, with only one parameter { 'reference':
'str' }, this way user will be able to specify
file: {driver: reference, reference: NODE_NAME, child-slot-id: NEW_ID}
Unfortunately, no: "../qapi/block-core.json:4781: alternate has unknown key
'base'"
Anyway, I believe, some solution should exist, probably by improving QAPI generator. Or, add
"child-slot-id" to base of BlockdevOptions, and add virtual "reference"
BlockdevDriver, to handle case with reference.
----
And finally, the new command becomes as simple as:
{ 'command': 'blockdev-replace',
'data': {'child-slot': 'str', 'new-child': 'str' } }
--
Best regards,
Vladimir
