libceph: un-backoff on tick when we have a authenticated session

This means that if we do some backoff, then authenticate, and are
healthy for an extended period of time, a subsequent failure won't
leave us starting our hunting sequence with a large backoff.

Mirrors ceph.git commit d466bc6e66abba9b464b0b69687cf45c9dccf383.

Cc: stable@vger.kernel.org # 4.7+
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jason Dillaman <dillaman@redhat.com>

net/ceph/mon_client.c

@@ -209,6 +209,14 @@ static void reopen_session(struct ceph_mon_client *monc)
 	__open_session(monc);
 }
 
+static void un_backoff(struct ceph_mon_client *monc)
+{
+	monc->hunt_mult /= 2; /* reduce by 50% */
+	if (monc->hunt_mult < 1)
+		monc->hunt_mult = 1;
+	dout("%s hunt_mult now %d\n", __func__, monc->hunt_mult);
+}
+
 /*
  * Reschedule delayed work timer.
  */
@@ -963,6 +971,7 @@ static void delayed_work(struct work_struct *work)
 		if (!monc->hunting) {
 			ceph_con_keepalive(&monc->con);
 			__validate_auth(monc);
+			un_backoff(monc);
 		}
 
 		if (is_auth &&
@@ -1123,9 +1132,7 @@ static void finish_hunting(struct ceph_mon_client *monc)
 		dout("%s found mon%d\n", __func__, monc->cur_mon);
 		monc->hunting = false;
 		monc->had_a_connection = true;
-		monc->hunt_mult /= 2; /* reduce by 50% */
-		if (monc->hunt_mult < 1)
-			monc->hunt_mult = 1;
+		un_backoff(monc);
 	}
 }