Fix undefined method reject! in allowed_storages

In the case where a StorageProfile is selected we were failing to filter
out the allowed storages due to the `storages` variable now being an
ActiveRecord Association where `#reject!` isn't defined.

This also resolves an N+1 issue where each storage queries for all
storage_profiles.

app/models/miq_request_workflow.rb

@@ -1076,11 +1076,9 @@ def allowed_storages(_options = {})
     rails_logger('allowed_storages', 0)
     st = Time.now
 
-    storages = Storage.where(:id => HostStorage.writable_accessible.where(:host => hosts).select(:storage_id))
     selected_storage_profile_id = get_value(@values[:placement_storage_profile])
-    if selected_storage_profile_id
-      storages.reject! { |s| !s.storage_profiles.pluck(:id).include?(selected_storage_profile_id) }
-    end
+    storages = selected_storage_profile_id ? StorageProfile.find(selected_storage_profile_id).storages : Storage.all
+    storages = storages.where(:id => HostStorage.writable_accessible.where(:host => hosts).select(:storage_id))
     allowed_storages_cache = process_filter(:ds_filter, Storage, storages).collect do |s|
       ci_to_hash_struct(s)
     end

spec/models/miq_request_workflow_spec.rb

@@ -253,6 +253,7 @@
     let(:ems)           { FactoryBot.create(:ext_management_system) }
     let(:resource_pool) { FactoryBot.create(:resource_pool, :ems_id => ems.id) }
     let(:host)          { FactoryBot.create(:host, :ems_id => ems.id) }
+    let(:storage)       { FactoryBot.create(:storage, :ems_id => ems.id) }
 
     before { allow_any_instance_of(User).to receive(:get_timezone).and_return("UTC") }
 
@@ -313,6 +314,55 @@
         workflow.allowed_clusters
       end
     end
+
+    context "#allowed_storages" do
+      it "filters out storages not mounted to allowed hosts" do
+        allow(workflow).to receive(:get_source_and_targets).and_return(:ems => workflow.ci_to_hash_struct(ems))
+        allow(workflow).to receive(:allowed_hosts_obj).and_return([host])
+
+        expect(workflow.allowed_storages).to be_empty
+      end
+
+      context "with writable storages" do
+        let!(:host_storage) { FactoryBot.create(:host_storage, :host => host, :storage => storage) }
+
+        it "returns all storages" do
+          allow(workflow).to receive(:get_source_and_targets).and_return(:ems => workflow.ci_to_hash_struct(ems))
+          allow(workflow).to receive(:allowed_hosts_obj).and_return([host])
+
+          storages = workflow.allowed_storages
+          expect(storages.count).to eq(1)
+          expect(storages.first).to have_attributes(:id => storage.id)
+        end
+      end
+
+      context "with read-only storages" do
+        let!(:host_storage) { FactoryBot.create(:host_storage, :host => host, :storage => storage, :read_only => true) }
+
+        it "filters out read-only storages" do
+          allow(workflow).to receive(:get_source_and_targets).and_return(:ems => workflow.ci_to_hash_struct(ems))
+          allow(workflow).to receive(:allowed_hosts_obj).and_return([host])
+
+          expect(workflow.allowed_storages).to be_empty
+        end
+      end
+
+      context "with a selected storage profile" do
+        let!(:host_storage) { FactoryBot.create(:host_storage, :host => host, :storage => storage) }
+        let!(:storage_profile) { FactoryBot.create(:storage_profile, :ems_id => ems.id) }
+
+        before do
+          workflow.values[:placement_storage_profile] = [storage_profile.id, storage_profile.name]
+        end
+
+        it "filters out storages not in the storage profile" do
+          allow(workflow).to receive(:get_source_and_targets).and_return(:ems => workflow.ci_to_hash_struct(ems))
+          allow(workflow).to receive(:allowed_hosts_obj).and_return([host])
+
+          expect(workflow.allowed_storages).to be_empty
+        end
+      end
+    end
   end
 
   context "#ci_to_hash_struct" do