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>

2 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/drbd_genl.h b/include/linux/drbd_genl.h
index 71fc924c53fa..7b131ed8f9c6 100644
--- 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 9d2df1d51414..8ac8c5d9a3ad 100644
--- 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