ceph: properly put ceph_string reference after async create attempt

The reference acquired by try_prep_async_create is currently leaked.
Ensure we put it.

Cc: stable@vger.kernel.org
Fixes: 9a8d03ca ("ceph: attempt to do async create when possible")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/file.c

@@ -750,8 +750,10 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 				restore_deleg_ino(dir, req->r_deleg_ino);
 				ceph_mdsc_put_request(req);
 				try_async = false;
+				ceph_put_string(rcu_dereference_raw(lo.pool_ns));
 				goto retry;
 			}
+			ceph_put_string(rcu_dereference_raw(lo.pool_ns));
 			goto out_req;
 		}
 	}