ceph: fix message order check in handle_cap_export()

If caps for importer mds exists, but cap id mismatch, client should
have received corresponding import message. Because cap ID does not
change as long as client holds the caps.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/caps.c

@@ -3427,7 +3427,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 	tcap = __get_cap_for_mds(ci, target);
 	if (tcap) {
 		/* already have caps from the target */
-		if (tcap->cap_id != t_cap_id ||
+		if (tcap->cap_id == t_cap_id &&
 		    ceph_seq_cmp(tcap->seq, t_seq) < 0) {
 			dout(" updating import cap %p mds%d\n", tcap, target);
 			tcap->cap_id = t_cap_id;