title: SVN commit error says attempt to write a readonly database
body: <p>I'm maintaining SVN server on an Ubuntu machine. And currently for some reason it didn't allow to commit. While commit it display following error message.</p>
  
  <pre><code>Warning: post-commit FS processing had error 'attempt to write a readonly database'.
  </code></pre>
  
  <p>How can I fix this issue?</p>