Add dedicated volume scan endpoint

Allows an imported volume to be scanned for stats independently.

Designed to be used as part of a snapshot import via API, to allow the
"create" to happen before the real import (to check for available space,
etc.) and then run this import after when the RBD volume actually
exists.

api-daemon/pvcapid/flaskapi.py

@@ -6461,6 +6461,41 @@ api.add_resource(
 )
 
 
+# /storage/ceph/volume/<pool>/<volume>/scan
+class API_Storage_Ceph_Volume_Element_Scan(Resource):
+    @Authenticator
+    def post(self, pool, volume):
+        """
+        Scan a Ceph volume {volume} in pool {pool} for stats (after import)
+        ---
+        tags:
+          - storage / ceph
+        parameters:
+        responses:
+          200:
+            description: OK
+            schema:
+              type: object
+              id: Message
+          404:
+            description: Not found
+            schema:
+              type: object
+              id: Message
+          400:
+            description: Bad request
+            schema:
+              type: object
+              id: Message
+        """
+        return api_helper.ceph_volume_scan(pool, volume)
+
+
+api.add_resource(
+    API_Storage_Ceph_Volume_Element_Scan, "/storage/ceph/volume/<pool>/<volume>/scan"
+)
+
+
 # /storage/ceph/volume/<pool>/<volume>/clone
 class API_Storage_Ceph_Volume_Element_Clone(Resource):
     @RequestParser(