Comment 3 for bug 1471890

I agree with Seth's suggestion, but for other reasons. We can't allow access to /proc/[0-9]*/mounts because it may contain sensitive information. Reading the directory contents of /dev/disk/by-label/ is likely ok (though there is also 'by-uuid' and 'by-id'). Can the calculation skip using /proc/[0-9]*/mounts and just use /dev/disk/by-label/? Ideally, the policy should not have to change at all and the app would talk to an out of process storage api (that is reasonable! :) to get this information.