drbd: New net configuration option socket-check-timeout

In setups involving a DRBD-proxy and connections that experience a lot of
buffer-bloat it might be necessary to set ping-timeout to an
unusual high value. By default DRBD uses the same value to wait if a newly
established TCP-connection is stable. Since the DRBD-proxy is usually located
in the same data center such a long wait time may hinder DRBD's connect process.

In such setups socket-check-timeout should be set to
at least to the round trip time between DRBD and DRBD-proxy. I.e. in most
cases to 1.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 7da83f3a61eb392e666d5b12ca5e682f1906e2ac..b89e6fb468c65e78049ae8e71d54fa3ee5044301 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -819,7 +819,7 @@ static int receive_first_packet(struct drbd_connection *connection, struct socke
  * drbd_socket_okay() - Free the socket if its connection is not okay
  * @sock:      pointer to the pointer to the socket.
  */
-static int drbd_socket_okay(struct socket **sock)
+static bool drbd_socket_okay(struct socket **sock)
 {
        int rr;
        char tb[4];
@@ -837,6 +837,30 @@ static int drbd_socket_okay(struct socket **sock)
                return false;
        }
 }
+
+static bool connection_established(struct drbd_connection *connection,
+                                  struct socket **sock1,
+                                  struct socket **sock2)
+{
+       struct net_conf *nc;
+       int timeout;
+       bool ok;
+
+       if (!*sock1 || !*sock2)
+               return false;
+
+       rcu_read_lock();
+       nc = rcu_dereference(connection->net_conf);
+       timeout = (nc->sock_check_timeo ?: nc->ping_timeo) * HZ / 10;
+       rcu_read_unlock();
+       schedule_timeout_interruptible(timeout);
+
+       ok = drbd_socket_okay(sock1);
+       ok = drbd_socket_okay(sock2) && ok;
+
+       return ok;
+}
+
 /* Gets called if a connection is established, or if a new minor gets created
    in a connection */
 int drbd_connected(struct drbd_peer_device *peer_device)
@@ -878,8 +902,8 @@ static int conn_connect(struct drbd_connection *connection)
        struct drbd_socket sock, msock;
        struct drbd_peer_device *peer_device;
        struct net_conf *nc;
-       int vnr, timeout, h, ok;
-       bool discard_my_data;
+       int vnr, timeout, h;
+       bool discard_my_data, ok;
        enum drbd_state_rv rv;
        struct accept_wait_data ad = {
                .connection = connection,
@@ -923,17 +947,8 @@ static int conn_connect(struct drbd_connection *connection)
                        }
                }
 
-               if (sock.socket && msock.socket) {
-                       rcu_read_lock();
-                       nc = rcu_dereference(connection->net_conf);
-                       timeout = nc->ping_timeo * HZ / 10;
-                       rcu_read_unlock();
-                       schedule_timeout_interruptible(timeout);
-                       ok = drbd_socket_okay(&sock.socket);
-                       ok = drbd_socket_okay(&msock.socket) && ok;
-                       if (ok)
-                               break;
-               }
+               if (connection_established(connection, &sock.socket, &msock.socket))
+                       break;
 
 retry:
                s = drbd_wait_for_connect(connection, &ad);
@@ -979,8 +994,7 @@ randomize:
                                goto out_release_sockets;
                }
 
-               ok = drbd_socket_okay(&sock.socket);
-               ok = drbd_socket_okay(&msock.socket) && ok;
+               ok = connection_established(connection, &sock.socket, &msock.socket);
        } while (!ok);
 
        if (ad.s_listen)

diff --git a/include/linux/drbd_genl.h b/include/linux/drbd_genl.h
index 71fc924c53fad09c2b337b7d481addfd56c3d349..7b131ed8f9c6696cfb1ec8b470c0d77c95dff07e 100644 (file)
--- a/include/linux/drbd_genl.h
+++ b/include/linux/drbd_genl.h
@@ -174,6 +174,7 @@ GENL_struct(DRBD_NLA_NET_CONF, 5, net_conf,
        /* 9: __str_field_def(31,     DRBD_GENLA_F_MANDATORY, name, SHARED_SECRET_MAX) */
        /* 9: __u32_field(32,         DRBD_F_REQUIRED | DRBD_F_INVARIANT,     peer_node_id) */
        __flg_field_def(33, 0 /* OPTIONAL */,   csums_after_crash_only, DRBD_CSUMS_AFTER_CRASH_ONLY_DEF)
+       __u32_field_def(34, 0 /* OPTIONAL */, sock_check_timeo, DRBD_SOCKET_CHECK_TIMEO_DEF)
 )
 
 GENL_struct(DRBD_NLA_SET_ROLE_PARMS, 6, set_role_parms,

diff --git a/include/linux/drbd_limits.h b/include/linux/drbd_limits.h
index 9d2df1d51414113df04a1ca69242b7747b0a22e5..8ac8c5d9a3ad08482bee1bcd0e5d4c57603436a7 100644 (file)
--- a/include/linux/drbd_limits.h
+++ b/include/linux/drbd_limits.h
@@ -225,4 +225,9 @@
 #define DRBD_AL_STRIPE_SIZE_MAX   16777216
 #define DRBD_AL_STRIPE_SIZE_DEF   32
 #define DRBD_AL_STRIPE_SIZE_SCALE 'k' /* kilobytes */
+
+#define DRBD_SOCKET_CHECK_TIMEO_MIN 0
+#define DRBD_SOCKET_CHECK_TIMEO_MAX DRBD_PING_TIMEO_MAX
+#define DRBD_SOCKET_CHECK_TIMEO_DEF 0
+#define DRBD_SOCKET_CHECK_TIMEO_SCALE '1'
 #endif