While creating a new file in the mounted filesystem, the [directory] entry

is updated

properly and a subsequent 'ls' on the directory correctly shows the newly
created file entries, but after a reboot, I lose all this data!!!

The first things we need to know to narrow down this problem are:

- Do you lose the data if you just do an unmount/mount, or is a reboot
really required?

- Does your ->writepage routine get called to write out the directory
information in
  question at unmount time?  How about when you sync()?

I don't want to branch out the decision tree too far here, but another
question further down is are you calling mark_inode_dirty() on the
directory inode?