Use ancestor namespace_limit for checking size

When checking for repo size limits, we check
the ancestor namespace for namespace_limits

ee/app/models/ee/namespace.rb

@@ -101,7 +101,9 @@ module EE
     end
 
     def namespace_limit
-      super.presence || build_namespace_limit
+      limit = has_parent? ? root_ancestor.namespace_limit : super
+
+      limit.presence || build_namespace_limit
     end
 
     class_methods do

ee/changelogs/unreleased/vij-namespace-limits.yml

+---
+title: Fix sub-group projects being locked after storage purchase
+merge_request: 53249
+author:
+type: fixed

ee/spec/models/ee/namespace_spec.rb

@@ -1602,12 +1602,49 @@ RSpec.describe Namespace do
     end
   end
 
-  describe 'ensure namespace limit' do
-    it 'has namespace limit upon namespace initialization' do
-      namespace = build(:namespace)
+  describe '#namespace_limit' do
+    let(:namespace) { create(:namespace, parent: parent) }
+
+    subject(:namespace_limit) { namespace.namespace_limit }
+
+    context 'when there is a parent namespace' do
+      let_it_be(:parent) { create(:namespace) }
+
+      context 'with a namespace limit' do
+        it 'returns the parent namespace limit' do
+          parent_limit = create(:namespace_limit, namespace: parent)
+
+          expect(namespace_limit).to eq parent_limit
+          expect(namespace_limit).to be_persisted
+        end
+      end
+
+      context 'with no namespace limit' do
+        it 'builds namespace limit' do
+          expect(namespace_limit).to be_present
+          expect(namespace_limit).not_to be_persisted
+        end
+      end
+    end
+
+    context 'when there is no parent ancestor' do
+      let(:parent) { nil }
 
-      expect(namespace.namespace_limit).to be_present
-      expect(namespace.namespace_limit).not_to be_persisted
+      context 'with a namespace limit' do
+        it 'returns the namespace limit' do
+          limit = create(:namespace_limit, namespace: namespace)
+
+          expect(namespace_limit).to be_persisted
+          expect(namespace_limit).to eq limit
+        end
+      end
+
+      context 'with no namespace limit' do
+        it 'builds namespace limit' do
+          expect(namespace_limit).to be_present
+          expect(namespace_limit).not_to be_persisted
+        end
+      end
     end
   end