I think I'm close to having my dev environment set up exactly the way I want, but one final snag remains. I'm running VirtualBox on a Windows 7 64bit host, with my dev enviroment inside a Ubuntu 12.04 guest. I want to keep the files for my projects on the host filesystem - partly so I can access them when the Ubuntu guest is not running, but also so I can use Tortoise and other Windows based tools (cough Photoshop), and it also eases my backup scheme somewhat.

So I've got a folder "Rails" on my NTFS drive, which I've shared from the host with a user specifically created for the Ubuntu guest. The mount point has been set up and an entry added to fstab (cifs), using a credentials file and the options iocharset=utf8,file_mode=0777,dir_mode=07??77 This mounts fine and my Ubuntu user has both read and write permissions to the contents, but when I try to start my Rails app I get permission errors on any files the app needs to write to (e.g. the log file). What gives?