rbd: let con_work() handle backoff

Both ceph_fault() and con_work() include handling for imposing a
delay before doing further processing on a faulted connection.
The latter is used only if ceph_fault() is unable to.

Instead, just let con_work() always be responsible for implementing
the delay.  After setting up the delay value, set the BACKOFF flag
on the connection unconditionally and call queue_con() to ensure
con_work() will get called to handle it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -2398,24 +2398,8 @@ static void ceph_fault(struct ceph_connection *con)
 			con->delay = BASE_DELAY_INTERVAL;
 		else if (con->delay < MAX_DELAY_INTERVAL)
 			con->delay *= 2;
-		con->ops->get(con);
-		if (queue_delayed_work(ceph_msgr_wq, &con->work,
-				       round_jiffies_relative(con->delay))) {
-			dout("fault queued %p delay %lu\n", con, con->delay);
-		} else {
-			con->ops->put(con);
-			dout("fault failed to queue %p delay %lu, backoff\n",
-			     con, con->delay);
-			/*
-			 * In many cases we see a socket state change
-			 * while con_work is running and end up
-			 * queuing (non-delayed) work, such that we
-			 * can't backoff with a delay.  Set a flag so
-			 * that when con_work restarts we schedule the
-			 * delay then.
-			 */
-			set_bit(CON_FLAG_BACKOFF, &con->flags);
-		}
+		set_bit(CON_FLAG_BACKOFF, &con->flags);
+		queue_con(con);
 	}
 
 out_unlock: