Having recently repaired autofs' ability to recognise updates to maps
dynamically I found I needed to reintroduce the directory inode lookup
method (I broke the update recognition several versions ago, oops).

This patch does this and applies cleanly against 2.6.9-rc1-mm4.

As far as I can tell from testing it doesn't introduce any backward
incompatibilities.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>