net/ceph: Only clear SOCK_NOSPACE when there is sufficient space in the socket buffer (182fac26) · Commits · 戴 / test

The Ceph messenger would sometimes queue multiple work items to write data to a socket when the socket buffer was full. Fix this problem by making ceph_write_space() use SOCK_NOSPACE in the same way that net/core/stream.c:sk_stream_write_space() does, i.e., clearing it only when sufficient space is available in the socket buffer. Signed-off-by:

Jim Schutt <jaschut@sandia.gov> Reviewed-by:

Alex Elder <elder@dreamhost.com>

net/ceph/messenger.c

+12 −6

Original line number	Diff line number	Diff line
		@@ -143,16 +143,22 @@ static void ceph_write_space(struct sock *sk)
		struct ceph_connection *con =
		(struct ceph_connection *)sk->sk_user_data;

		/* only queue to workqueue if there is data we want to write. */
		/* only queue to workqueue if there is data we want to write,
		* and there is sufficient space in the socket buffer to accept
		* more data. clear SOCK_NOSPACE so that ceph_write_space()
		* doesn't get called again until try_write() fills the socket
		* buffer. See net/ipv4/tcp_input.c:tcp_check_space()
		* and net/core/stream.c:sk_stream_write_space().
		*/
		if (test_bit(WRITE_PENDING, &con->state)) {
		if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
		dout("ceph_write_space %p queueing write work\n", con);
		clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
		queue_con(con);
		}
		} else {
		dout("ceph_write_space %p nothing to write\n", con);
		}

		/* since we have our own write_space, clear the SOCK_NOSPACE flag */
		clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
		}

		/* socket's state has changed */

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