ceph: fix connection fault con_work reentrancy problem

The messenger fault was clearing the BUSY bit, for reasons unclear.  This
made it possible for the con->ops->fault function to reopen the connection,
and requeue work in the workqueue--even though the current thread was
already in con_work.

This avoids a problem where the client busy loops with connection failures
on an unreachable OSD, but doesn't address the root cause of that problem.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/messenger.c

@@ -1836,8 +1836,6 @@ static void ceph_fault(struct ceph_connection *con)
 		goto out;
 	}
 
-	clear_bit(BUSY, &con->state);  /* to avoid an improbable race */
-
 	mutex_lock(&con->mutex);
 	if (test_bit(CLOSED, &con->state))
 		goto out_unlock;