mds: fix check for no-op rename of two links to the same inode
mds: fix check for no-op rename of two links to the same inode

touch a
ln a b
mv a b

is a no-op, according to posix.  Move the check earlier.


Signed-off-by: Sage Weil <c5b6ff1fd4f0bde10db63d7a3e07166cf6c4229f@dreamhost.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph