Writing a file system driver. Would like to prevent multiple mounts over the same mountpoint. Prior to 2.5 the dentry structure had a d_covers field that pointed at the mountpoint. You could check that against the requested mountpoint to see if it was already in use.
I would rather not test the path of the device being mounted, because it could possibly be mounted elsewhere, I want to test the mountpoint so it is not overloaded with multiple mounts.
How do you do this without the now missing d_covers field?