ceph: make object hash a pg_pool property

The object will be hashed to a placement seed (ps) based on the pg_pool's
hash function.  This allows new hashes to be introduced into an existing
object store, or selection of a hash appropriate to the objects that
will be stored in a particular pool.

Signed-off-by: Sage Weil <sage@newdream.net>

diff --cc fs/ceph/Makefile
Simple merge

diff --cc fs/ceph/README
Simple merge

diff --cc fs/ceph/ceph_fs.c
Simple merge

diff --cc fs/ceph/ceph_fs.h
Simple merge

diff --cc fs/ceph/ceph_hash.c
Simple merge

diff --cc fs/ceph/ceph_hash.h
Simple merge

diff --cc fs/ceph/osdmap.c
Simple merge

diff --cc fs/ceph/rados.h
Simple merge

diff --cc fs/ceph/types.h
Simple merge