storage/v2: less invasive edit partition

subiquity/server/controllers/filesystem.py

@@ -355,9 +355,13 @@ class FilesystemController(SubiquityController, FilesystemManipulator):
     async def v2_edit_partition_POST(self, data: ModifyPartitionV2) \
             -> StorageResponseV2:
         partition = self.get_partition(data.disk_id, data.partition.number)
-        data.partition.size = partition.size
-        self.delete_partition(partition, True)
-        return await self.v2_add_partition_POST(data)
+        disk = self.model._one(id=data.disk_id)
+        spec = {
+            "fstype": data.partition.format,
+            "mount": data.partition.mount
+        }
+        self.partition_disk_handler(disk, partition, spec)
+        return await self.v2_GET()
 
     @with_context(name='probe_once', description='restricted={restricted}')
     async def _probe_once(self, *, context, restricted):