drbd: Keep the listening socket open while trying to connect to the peer

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

1 files changed, 54 insertions, 18 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 46c55793dd8d..9aac1c4033c7 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -666,7 +666,32 @@ out:
         return sock;
 }
 
-static struct socket *prepare_listen_socket(struct drbd_tconn *tconn)
+struct accept_wait_data {
+        struct drbd_tconn *tconn;
+        struct socket *s_listen;
+        struct completion door_bell;
+        void (*original_sk_state_change)(struct sock *sk);
+
+};
+
+static void incomming_connection(struct sock *sk)
+{
+        struct accept_wait_data *ad = sk->sk_user_data;
+        struct drbd_tconn *tconn = ad->tconn;
+
+        if (sk->sk_state != TCP_ESTABLISHED)
+                conn_warn(tconn, "unexpected tcp state change. sk_state = %d\n", sk->sk_state);
+
+        write_lock_bh(&sk->sk_callback_lock);
+        sk->sk_state_change = ad->original_sk_state_change;
+        sk->sk_user_data = NULL;
+        write_unlock_bh(&sk->sk_callback_lock);
+
+        sk->sk_state_change(sk);
+        complete(&ad->door_bell);
+}
+
+static int prepare_listen_socket(struct drbd_tconn *tconn, struct accept_wait_data *ad)
 {
         int err, sndbuf_size, rcvbuf_size, my_addr_len;
         struct sockaddr_in6 my_addr;
@@ -678,7 +703,7 @@ static struct socket *prepare_listen_socket(struct drbd_tconn *tconn)
         nc = rcu_dereference(tconn->net_conf);
         if (!nc) {
                 rcu_read_unlock();
-                return NULL;
+                return -EIO;
         }
         sndbuf_size = nc->sndbuf_size;
         rcvbuf_size = nc->rcvbuf_size;
@@ -703,12 +728,19 @@ static struct socket *prepare_listen_socket(struct drbd_tconn *tconn)
         if (err < 0)
                 goto out;
 
+        ad->s_listen = s_listen;
+        write_lock_bh(&s_listen->sk->sk_callback_lock);
+        ad->original_sk_state_change = s_listen->sk->sk_state_change;
+        s_listen->sk->sk_state_change = incomming_connection;
+        s_listen->sk->sk_user_data = ad;
+        write_unlock_bh(&s_listen->sk->sk_callback_lock);
+
         what = "listen";
         err = s_listen->ops->listen(s_listen, 5);
         if (err < 0)
                 goto out;
 
-        return s_listen;
+        return 0;
 out:
         if (s_listen)
                 sock_release(s_listen);
@@ -719,14 +751,13 @@ out:
                 }
         }
 
-        return NULL;
+        return -EIO;
 }
 
-static struct socket *drbd_wait_for_connect(struct drbd_tconn *tconn)
+static struct socket *drbd_wait_for_connect(struct drbd_tconn *tconn, struct accept_wait_data *ad)
 {
         int timeo, connect_int, err = 0;
         struct socket *s_estab = NULL;
-        struct socket *s_listen;
         struct net_conf *nc;
 
         rcu_read_lock();
@@ -741,18 +772,11 @@ static struct socket *drbd_wait_for_connect(struct drbd_tconn *tconn)
         timeo = connect_int * HZ;
         timeo += (random32() & 1) ? timeo / 7 : -timeo / 7; /* 28.5% random jitter */
 
-        s_listen = prepare_listen_socket(tconn);
-        if (!s_listen)
-                goto out;
-
-        s_listen->sk->sk_rcvtimeo = timeo;
-        s_listen->sk->sk_sndtimeo = timeo;
-
-        err = kernel_accept(s_listen, &s_estab, 0);
+        err = wait_for_completion_interruptible_timeout(&ad->door_bell, timeo);
+        if (err <= 0)
+                return NULL;
 
-out:
-        if (s_listen)
-                sock_release(s_listen);
+        err = kernel_accept(ad->s_listen, &s_estab, 0);
         if (err < 0) {
                 if (err != -EAGAIN && err != -EINTR && err != -ERESTARTSYS) {
                         conn_err(tconn, "accept failed, err = %d\n", err);
@@ -855,6 +879,10 @@ static int conn_connect(struct drbd_tconn *tconn)
         int vnr, timeout, try, h, ok;
         bool discard_my_data;
         enum drbd_state_rv rv;
+        struct accept_wait_data ad = {
+                .tconn = tconn,
+                .door_bell = COMPLETION_INITIALIZER_ONSTACK(ad.door_bell),
+        };
 
         if (conn_request_state(tconn, NS(conn, C_WF_CONNECTION), CS_VERBOSE) < SS_SUCCESS)
                 return -2;
@@ -873,6 +901,9 @@ static int conn_connect(struct drbd_tconn *tconn)
         /* Assume that the peer only understands protocol 80 until we know better.  */
         tconn->agreed_pro_version = 80;
 
+        if (prepare_listen_socket(tconn, &ad))
+                return 0;
+
         do {
                 struct socket *s;
 
@@ -911,7 +942,7 @@ static int conn_connect(struct drbd_tconn *tconn)
                 }
 
 retry:
-                s = drbd_wait_for_connect(tconn);
+                s = drbd_wait_for_connect(tconn, &ad);
                 if (s) {
                         try = receive_first_packet(tconn, s);
                         drbd_socket_okay(&sock.socket);
@@ -957,6 +988,9 @@ retry:
                 }
         } while (1);
 
+        if (ad.s_listen)
+                sock_release(ad.s_listen);
+
         sock.socket->sk->sk_reuse = 1; /* SO_REUSEADDR */
         msock.socket->sk->sk_reuse = 1; /* SO_REUSEADDR */
 
@@ -1052,6 +1086,8 @@ retry:
         return h;
 
 out_release_sockets:
+        if (ad.s_listen)
+                sock_release(ad.s_listen);
         if (sock.socket)
                 sock_release(sock.socket);
         if (msock.socket)