[Qemu-block] [PATCH v4 3/4] qmp: add monitor command to add/remove a child

[Wen Congyang]

Signed-off-by: Wen Congyang <address@hidden>
Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Gonglei <address@hidden>
---
 blockdev.c           | 48 ++++++++++++++++++++++++++++++++++++++++++++++
 qapi/block-core.json | 34 +++++++++++++++++++++++++++++++++
 qmp-commands.hx      | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index 32b04b4..8da0ffb 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3086,6 +3086,54 @@ fail:
     qmp_output_visitor_cleanup(ov);
 }
 
+void qmp_x_blockdev_child_add(const char *parent, const char *child,
+                              Error **errp)
+{
+    BlockDriverState *parent_bs, *child_bs;
+    Error *local_err = NULL;
+
+    parent_bs = bdrv_lookup_bs(parent, parent, &local_err);
+    if (!parent_bs) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    child_bs = bdrv_find_node(child);
+    if (!child_bs) {
+        error_setg(errp, "Node '%s' not found", child);
+        return;
+    }
+
+    bdrv_add_child(parent_bs, child_bs, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+    }
+}
+
+void qmp_x_blockdev_child_del(const char *parent, const char *child,
+                              Error **errp)
+{
+    BlockDriverState *parent_bs, *child_bs;
+    Error *local_err = NULL;
+
+    parent_bs = bdrv_lookup_bs(parent, parent, &local_err);
+    if (!parent_bs) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    child_bs = bdrv_find_node(child);
+    if (!child_bs) {
+        error_setg(errp, "Node '%s' not found", child);
+        return;
+    }
+
+    bdrv_del_child(parent_bs, child_bs, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+    }
+}
+
 BlockJobInfoList *qmp_query_block_jobs(Error **errp)
 {
     BlockJobInfoList *head = NULL, **p_next = &head;
diff --git a/qapi/block-core.json b/qapi/block-core.json
index bb2189e..9418f05 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2114,3 +2114,37 @@
 ##
 { 'command': 'block-set-write-threshold',
   'data': { 'node-name': 'str', 'write-threshold': 'uint64' } }
+
+##
+# @x-blockdev-child-add
+#
+# Add a new child to the parent BDS. Currently only the Quorum driver
+# implements this feature. This is useful to fix a broken quorum child.
+#
+# @parent: graph node name or id which the child will be added to.
+#
+# @child: graph node name that will be added.
+#
+# Note: this command is experimental, and not a stable API.
+#
+# Since: 2.5
+##
+{ 'command': 'x-blockdev-child-add',
+  'data' : { 'parent': 'str', 'child': 'str' } }
+
+##
+# @x-blockdev-child-del
+#
+# Remove a child from the parent BDS. Currently only the Quorum driver
+# implements this feature. This is useful to fix a broken quorum child.
+# Note, you can't remove a child if it would bring the quorum below its
+# threshold.
+#
+# @parent: graph node name or id from which the child will removed.
+#
+# @child: graph node name that will be removed.
+#
+# Since: 2.5
+##
+{ 'command': 'x-blockdev-child-del',
+  'data' : { 'parent': 'str', 'child': 'str' } }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 9848fd8..11a007d 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3897,6 +3897,60 @@ Example (2):
 EQMP
 
     {
+        .name       = "x-blockdev-child-add",
+        .args_type  = "parent:B,child:B",
+        .mhandler.cmd_new = qmp_marshal_input_x_blockdev_child_add,
+    },
+
+SQMP
+x-blockdev-child-add
+------------
+
+Add a child to a quorum node.
+
+Arguments:
+
+- "parent": the quorum's id or node name
+- "child": the child node-name which will be added
+
+Note: this command is experimental, and not a stable API. It doesn't
+support all kinds of child, and not support all block drivers.
+
+Example:
+
+-> { "execute": "x-blockdev-child-add",
+    "arguments": { "parent": "disk1", "child": "new_node" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name        = "x-blockdev-child-del",
+        .args_type   = "parent:B,child:B",
+        .mhandler.cmd_new = qmp_marshal_input_x_blockdev_child_del,
+    },
+
+SQMP
+x-blockdev-child-del
+------------
+
+Delete a child from a quorum node. It can be used to remove a broken
+quorum child.
+
+Arguments:
+
+- "parent": the quorum's id or node name
+- "child": the child node-name which will be removed
+
+Example:
+
+-> { "execute": "x-blockdev-child-del",
+    "arguments": { "parent": "disk1", "child": "new_node" } }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "query-named-block-nodes",
         .args_type  = "",
         .mhandler.cmd_new = qmp_marshal_input_query_named_block_nodes,
-- 
2.4.3