libceph: report connection fault with warning

When a connection's socket disconnects, or if there's a protocol
error of some kind on the connection, a fault is signaled and
the connection is reset (closed and reopened, basically).  We
currently get an error message on the log whenever this occurs.

A ceph connection will attempt to reestablish a socket connection
repeatedly if a fault occurs.  This means that these error messages
will get repeatedly added to the log, which is undesirable.

Change the error message to be a warning, so they don't get
logged by default.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -2377,7 +2377,7 @@ static void con_work(struct work_struct *work)
 static void ceph_fault(struct ceph_connection *con)
 	__releases(con->mutex)
 {
-	pr_err("%s%lld %s %s\n", ENTITY_NAME(con->peer_name),
+	pr_warning("%s%lld %s %s\n", ENTITY_NAME(con->peer_name),
 	       ceph_pr_addr(&con->peer_addr.in_addr), con->error_msg);
 	dout("fault %p state %lu to peer %s\n",
 	     con, con->state, ceph_pr_addr(&con->peer_addr.in_addr));