Enable automatic hashed storage for new projects by application settings

app/helpers/application_settings_helper.rb

@@ -116,6 +116,7 @@ module ApplicationSettingsHelper
       :email_author_in_body,
       :enabled_git_access_protocol,
       :gravatar_enabled,
+      :hashed_storage_enabled,
       :help_page_hide_commercial_content,
       :help_page_support_url,
       :help_page_text,

app/models/project.rb

@@ -24,6 +24,7 @@ class Project < ActiveRecord::Base
   NUMBER_OF_PERMITTED_BOARDS = 1
   UNKNOWN_IMPORT_URL = 'http://unknown.git'.freeze
+  LATEST_STORAGE_VERSION = 1
   cache_markdown_field :description, pipeline: :description
@@ -1428,6 +1429,9 @@ class Project < ActiveRecord::Base
     if self.storage_version && self.storage_version >= 1
       self.extend Storage::HashedProject
+    elsif !self.persisted? && current_application_settings.hashed_storage_enabled
+      self.storage_version = LATEST_STORAGE_VERSION
+      self.extend Storage::HashedProject
     else
       self.extend Storage::LegacyProject
     end

app/views/admin/application_settings/_form.html.haml

@@ -492,6 +492,16 @@
   %fieldset
     %legend Repository Storage
+    .form-group
+      .col-sm-offset-2.col-sm-10
+        .checkbox
+          = f.label :hashed_storage_enabled do
+            = f.check_box :hashed_storage_enabled
+            Create new projects using hashed storage paths
+          .help-block
+            Enable immutable, hash based paths and repository names to store repositories on disk. This prevents
+            repositories from having to be moved or renamed when the Project URL changes and may improve disk I/O performance.
+            %em (EXPERIMENTAL)
     .form-group
       = f.label :repository_storages, 'Storage paths for new projects', class: 'control-label col-sm-2'
       .col-sm-10
@@ -501,6 +511,7 @@
           = succeed "." do
             = link_to "repository storages documentation", help_page_path("administration/repository_storages")
+
   %fieldset
     %legend Repository Checks
     .form-group

db/migrate/20170807071105_add_hashed_storage_to_settings.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddHashedStorageToSettings < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_column_with_default :application_settings, :hashed_storage_enabled, :boolean, default: false
+  end
+
+  def down
+    remove_columns :application_settings, :hashed_storage_enabled
+  end
+end

db/schema.rb

@@ -128,6 +128,7 @@ ActiveRecord::Schema.define(version: 20170820100558) do
     t.integer "performance_bar_allowed_group_id"
     t.boolean "password_authentication_enabled"
     t.boolean "project_export_enabled", default: true, null: false
+    t.boolean "hashed_storage_enabled", default: false, null: false
   end
   create_table "audit_events", force: :cascade do |t|