mds: fix discover_path
mds: fix discover_path

If we have the base dirfrag, do not request it.  Otherwise we can get a
reply that contains only that (partial progress), and we will then fail
to wake up our dentry waiter.

This was broken with the rewrite in b58b8d098e4c.

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

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