Refresh all files in buffer from disk in vim
The :checkt[ime] command is designed for this very purpose.
It will prompt you to reload any buffers that have changed; if you wish to skip the prompt, you can do :set autoread beforehand (you'll still get a prompt on buffers with local unsaved changes).
It also avoids the syntax highlighting issue mentioned by Steven Lu on the accepted answer; :bufdo turns off syntax highlighting by design.