assets_recipe.rb

namespace :assets do
  task :symlink, :roles => :app do
    assets.create_dir
    run <<-CMD
      rm -rf  #{current_path}/public/images/upload &&
      ln -nfs #{shared_path}/upload #{release_path}/public/images/upload
    CMD
  end
  
  task :create_dir, :roles => :app do
    run "test -d #{shared_path}/upload || mkdir -p #{shared_path}/upload"
  end
end

after "deploy:update_code","assets:symlink"