This stuff is kind of bogus. If you do a mount while chrooted, the
full path to the mount point isn't recorded, so mount only displays
the partial path. How are you supposed to find the mount point again?
It would be nice if the path to the chroot directory was preserved so
that the full path could be recorded in the kernel, but this sort of
goes against the grain of the Unix philosophy.
Even with the full path name in the mount table, you can still mess
things up by renaming one of the intermediate directories ...
Having a 'full path name' for an arbitrary file at a useful time (prior or
after its vnode lookup) would be great for a number of applications
(well, kernel features :) that need to report to the user. This includes
auditing support, where having a name guaranteed unique at the time where
it is used. Also useful, but possibly more prone to pain, would be a
Posix.1e auditing references filenames in the audit records, hence my
interest at this point.