"user data" in transactions / logged writes

[Aaron Smith <aaron@xxxxxxxxx>]

hello,

i've been reading over some of the xfs papers, and i noticed the following
in "xFS project architecture, October 8, 1993":

   3.3 xFS Growth Path

   In the long run, we expect to add user-level transactions to the file
   system, at which time selected user data will be logged along with the
   filesystem metadata. This feature will make it practical for user
   applications to easily implement databases and database-like systems on
   top of this file system.

is this essentially logged writes? does xfs have any support for
journalling written file data? please let me know if you know of anyone
who's working on it, or if you understand what pitfalls would need to be
addressed to make it possible.

thanks,
aaron