qmp: add interface blockdev-snapshot-delete-internal-sync

This interface use id and name as optional parameters, to handle the
case that one image contain multiple snapshots with same name which
may be '', but with different id.

Adding parameter id is for historical compatiability reason, and
that case is not possible in qemu's new interface for internal
snapshot at block device level, but still possible in qemu-img.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qmp-commands.hx

@@ -1124,6 +1124,47 @@ Example:
    }
 <- { "return": {} }
 
+EQMP
+
+    {
+        .name       = "blockdev-snapshot-delete-internal-sync",
+        .args_type  = "device:B,id:s?,name:s?",
+        .mhandler.cmd_new =
+                      qmp_marshal_input_blockdev_snapshot_delete_internal_sync,
+    },
+
+SQMP
+blockdev-snapshot-delete-internal-sync
+--------------------------------------
+
+Synchronously delete an internal snapshot of a block device when the format of
+image used supports it.  The snapshot is identified by name or id or both.  One
+of name or id is required.  If the snapshot is not found, the operation will
+fail.
+
+Arguments:
+
+- "device": device name (json-string)
+- "id": ID of the snapshot (json-string, optional)
+- "name": name of the snapshot (json-string, optional)
+
+Example:
+
+-> { "execute": "blockdev-snapshot-delete-internal-sync",
+                "arguments": { "device": "ide-hd0",
+                               "name": "snapshot0" }
+   }
+<- { "return": {
+                   "id": "1",
+                   "name": "snapshot0",
+                   "vm-state-size": 0,
+                   "date-sec": 1000012,
+                   "date-nsec": 10,
+                   "vm-clock-sec": 100,
+                   "vm-clock-nsec": 20
+     }
+   }
+
 EQMP
 
     {