net/rds: Add setsockopt support for SO_RDS_TRANSPORT

An application may deterministically attach the underlying transport for
a PF_RDS socket by invoking setsockopt(2) with the SO_RDS_TRANSPORT
option at the SOL_RDS level. The integer argument to setsockopt must be
one of the RDS_TRANS_* transport types, e.g., RDS_TRANS_TCP. The option
must be specified before invoking bind(2) on the socket, and may only
be used once on the socket. An attempt to set the option on a bound
socket, or to invoke the option after a successful SO_RDS_TRANSPORT
attachment, will return EOPNOTSUPP.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index 3d83641f2861f7561fbf1a7bea0b5db9a7063d75..04877441fb013042570948169334057757d5d6bf 100644 (file)
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -270,6 +270,28 @@ static int rds_cong_monitor(struct rds_sock *rs, char __user *optval,
        return ret;
 }
 
+static int rds_set_transport(struct rds_sock *rs, char __user *optval,
+                            int optlen)
+{
+       int t_type;
+
+       if (rs->rs_transport)
+               return -EOPNOTSUPP; /* previously attached to transport */
+
+       if (optlen != sizeof(int))
+               return -EINVAL;
+
+       if (copy_from_user(&t_type, (int __user *)optval, sizeof(t_type)))
+               return -EFAULT;
+
+       if (t_type < 0 || t_type >= RDS_TRANS_COUNT)
+               return -EINVAL;
+
+       rs->rs_transport = rds_trans_get(t_type);
+
+       return rs->rs_transport ? 0 : -ENOPROTOOPT;
+}
+
 static int rds_setsockopt(struct socket *sock, int level, int optname,
                          char __user *optval, unsigned int optlen)
 {
@@ -300,6 +322,11 @@ static int rds_setsockopt(struct socket *sock, int level, int optname,
        case RDS_CONG_MONITOR:
                ret = rds_cong_monitor(rs, optval, optlen);
                break;
+       case SO_RDS_TRANSPORT:
+               lock_sock(sock->sk);
+               ret = rds_set_transport(rs, optval, optlen);
+               release_sock(sock->sk);
+               break;
        default:
                ret = -ENOPROTOOPT;
        }

diff --git a/net/rds/bind.c b/net/rds/bind.c
index a2e6562da751f79bd9524c7e434f1d1d02d3b4fe..4ebd29c128b63f7c9519a421128351b5e502853a 100644 (file)
--- a/net/rds/bind.c
+++ b/net/rds/bind.c
@@ -181,6 +181,10 @@ int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
        if (ret)
                goto out;
 
+       if (rs->rs_transport) { /* previously bound */
+               ret = 0;
+               goto out;
+       }
        trans = rds_trans_get_preferred(sin->sin_addr.s_addr);
        if (!trans) {
                ret = -EADDRNOTAVAIL;

diff --git a/net/rds/rds.h b/net/rds/rds.h
index 76db508f73a1ae67e808cc87ea6d93a5a26c2398..a33fb4ad3535b57d305c0e5dae0e9f6bd8415104 100644 (file)
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -798,6 +798,7 @@ struct rds_transport *rds_trans_get_preferred(__be32 addr);
 void rds_trans_put(struct rds_transport *trans);
 unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
                                       unsigned int avail);
+struct rds_transport *rds_trans_get(int t_type);
 int rds_trans_init(void);
 void rds_trans_exit(void);
 

diff --git a/net/rds/transport.c b/net/rds/transport.c
index 7f2ac4fec3678b28715b95094c6346bcc49333e1..8b4a6cd2c3a78f0a4c7dbbf89fbe1bd6156aeb55 100644 (file)
--- a/net/rds/transport.c
+++ b/net/rds/transport.c
@@ -101,6 +101,27 @@ struct rds_transport *rds_trans_get_preferred(__be32 addr)
        return ret;
 }
 
+struct rds_transport *rds_trans_get(int t_type)
+{
+       struct rds_transport *ret = NULL;
+       struct rds_transport *trans;
+       unsigned int i;
+
+       down_read(&rds_trans_sem);
+       for (i = 0; i < RDS_TRANS_COUNT; i++) {
+               trans = transports[i];
+
+               if (trans && trans->t_type == t_type &&
+                   (!trans->t_owner || try_module_get(trans->t_owner))) {
+                       ret = trans;
+                       break;
+               }
+       }
+       up_read(&rds_trans_sem);
+
+       return ret;
+}
+
 /*
  * This returns the number of stats entries in the snapshot and only
  * copies them using the iter if there is enough space for them.  The