Preserve btrfs options for root (bsc#965279)

src/include/partitioning/custom_part_lib.rb

@@ -631,7 +631,10 @@ def HandleFsChanged(init, new, old_fs, file_systems)
     # @param file_systems [Hash] definitions of the supported filesystems
     # @param old [Hash] map with original partition
     # @param new [Hash] map with changes filled in
-    def HandlePartWidgetChanges(init, ret, file_systems, old, new)
+    # @param force_defaults [Boolean] whether to overwrite all the properties
+    #     (like the list of subvolumes) with the expert partitioner default values.
+    #     Useful when creating a partition for the first time
+    def HandlePartWidgetChanges(init, ret, file_systems, old, new, force_defaults: false)
       ret = deep_copy(ret)
       file_systems = deep_copy(file_systems)
       old = deep_copy(old)
@@ -673,7 +676,8 @@ def HandlePartWidgetChanges(init, ret, file_systems, old, new)
       end
 
       # set btrfs subvolumes (bnc#872210)
-      if init && new.fetch("mount", "") == "/"
+      # only when requested from the caller (i.e. new partition) (bsc#965279)
+      if init && new.fetch("mount", "") == "/" && force_defaults
         new = HandleSubvol(new)
       end
 

src/include/partitioning/ep-dialogs.rb

@@ -130,7 +130,12 @@ def MiniWorkflowStepFormatMountHelptext
     end
 
 
-    def MiniWorkflowStepFormatMount(orig_data)
+    # Workflow used to specify the format and options of a partition
+    # It is used during creation and during modification
+    # @param orig_data [ArgRef] reference to the map with partition information
+    # @param creating [Boolean] whether this call is part of the creation process
+    #       of the partition (not a modification)
+    def MiniWorkflowStepFormatMount(orig_data, creating: false)
       data = orig_data.value
       d = Storage.GetDiskPartition(Ops.get_string(data, "device", ""))
       lbl = Ops.get_string(
@@ -443,7 +448,8 @@ def MiniWorkflowStepFormatMount(orig_data)
         widget,
         all_filesystems,
         orig_data.value,
-        data
+        data,
+        force_defaults: creating
       )
       begin
         widget = MiniWorkflow.UserInput

src/include/partitioning/ep-hd-dialogs.rb

@@ -474,7 +474,8 @@ def DlgCreatePartition(data)
           (
             data_ref = arg_ref(data.value);
             _MiniWorkflowStepFormatMount_result = MiniWorkflowStepFormatMount(
-              data_ref
+              data_ref,
+              creating: true
             );
             data.value = data_ref.value;
             _MiniWorkflowStepFormatMount_result