Improve structure of lfs_file_locks table

app/services/lfs/lock_file_service.rb

@@ -9,7 +9,7 @@ module Lfs
 
       create_lock!
     rescue ActiveRecord::RecordNotUnique
-      error('already created lock', 409, current_lock)
+      error('already locked', 409, current_lock)
     rescue Gitlab::GitAccess::UnauthorizedError => ex
       error(ex.message, 403)
     rescue => ex

db/migrate/20180116193854_create_lfs_file_locks.rb

@@ -3,12 +3,12 @@ class CreateLfsFileLocks < ActiveRecord::Migration
 
   def change
     create_table :lfs_file_locks do |t|
-      t.references :project, null: false, index: true, foreign_key: { on_delete: :cascade }
+      t.references :project, null: false, foreign_key: { on_delete: :cascade }
       t.references :user, null: false, index: true, foreign_key: { on_delete: :cascade }
-      t.string :path
       t.datetime :created_at, null: false
+      t.string :path, limit: 65500
     end
 
-    add_index :lfs_file_locks, [:path, :project_id], unique: true
+    add_index :lfs_file_locks, [:project_id, :path], unique: true
   end
 end

db/schema.rb

@@ -1305,12 +1305,11 @@ ActiveRecord::Schema.define(version: 20180204200836) do
   create_table "lfs_file_locks", force: :cascade do |t|
     t.integer "project_id", null: false
     t.integer "user_id", null: false
-    t.string "path"
     t.datetime "created_at", null: false
+    t.string "path", limit: 65500
   end
 
-  add_index "lfs_file_locks", ["path", "project_id"], name: "index_lfs_file_locks_on_path_and_project_id", unique: true, using: :btree
-  add_index "lfs_file_locks", ["project_id"], name: "index_lfs_file_locks_on_project_id", using: :btree
+  add_index "lfs_file_locks", ["project_id", "path"], name: "index_lfs_file_locks_on_project_id_and_path", unique: true, using: :btree
   add_index "lfs_file_locks", ["user_id"], name: "index_lfs_file_locks_on_user_id", using: :btree
 
   create_table "lfs_objects", force: :cascade do |t|

spec/requests/lfs_locks_api_spec.rb

@@ -52,7 +52,7 @@ describe 'Git LFS File Locking API' do
         expect(response).to have_gitlab_http_status(409)
 
         expect(json_response.keys).to match_array(%w(lock message documentation_url))
-        expect(json_response['message']).to match(/already created lock/)
+        expect(json_response['message']).to match(/already locked/)
       end
 
       it 'returns the existen lock' do