sunrpc: set SOCK_FASYNC

sunrpc is using SOCKWQ_ASYNC_NOSPACE without setting SOCK_FASYNC,
so the recent optimizations done in sk_set_bit() and sk_clear_bit()
broke it.

There is still the risk that a subsequent sock_fasync() call
would clear SOCK_FASYNC, but sunrpc does not use this yet.

Fixes: 9317bb69 ("net: SOCKWQ_ASYNC_NOSPACE optimizations")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NJiri Pirko <jiri@resnulli.us>
Reported-by: NHuang, Ying <ying.huang@intel.com>
Tested-by: NJiri Pirko <jiri@resnulli.us>
Tested-by: NHuang, Ying <ying.huang@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sunrpc/xprtsock.c

@@ -1950,6 +1950,7 @@ static int xs_local_finish_connecting(struct rpc_xprt *xprt,
 		sk->sk_user_data = xprt;
 		sk->sk_data_ready = xs_data_ready;
 		sk->sk_write_space = xs_udp_write_space;
+		sock_set_flag(sk, SOCK_FASYNC);
 		sk->sk_error_report = xs_error_report;
 		sk->sk_allocation = GFP_NOIO;
 
@@ -2136,6 +2137,7 @@ static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 		sk->sk_user_data = xprt;
 		sk->sk_data_ready = xs_data_ready;
 		sk->sk_write_space = xs_udp_write_space;
+		sock_set_flag(sk, SOCK_FASYNC);
 		sk->sk_allocation = GFP_NOIO;
 
 		xprt_set_connected(xprt);
@@ -2237,6 +2239,7 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 		sk->sk_data_ready = xs_tcp_data_ready;
 		sk->sk_state_change = xs_tcp_state_change;
 		sk->sk_write_space = xs_tcp_write_space;
+		sock_set_flag(sk, SOCK_FASYNC);
 		sk->sk_error_report = xs_error_report;
 		sk->sk_allocation = GFP_NOIO;