Update most of "include/linux/ceph/ceph_fs.h" to match its user
space counterpart in "src/include/ceph_fs.h" in the ceph tree.
Everything that has changed is either:
- added definitions (therefore no real effect on existing code)
- deleting unused symbols
- added or revised comments
There were some differences between the struct definitions for
ceph_mon_subscribe_item and the open field of ceph_mds_request_args;
those differences remain.
This and the next commit resolve:
http://tracker.ceph.com/issues/4165
Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>