RDS/IB: Disallow connections less than RDS 3.1

RDS 3.0 connections (in OFED 1.3 and earlier) put the
header at the end. 3.1 connections put it at the head.
The code has significant added complexity in order to
handle both configurations. In OFED 1.6 we can
drop this and simplify the code by only supporting
"header-first" configuration.

This patch checks the protocol version, and if prior
to 3.1, does not complete the connection.
Signed-off-by: Andy Grover <andy.grover@oracle.com>

net/rds/ib_cm.c

@@ -111,11 +111,21 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even
 		}
 	}
 
-	printk(KERN_NOTICE "RDS/IB: connected to %pI4 version %u.%u%s\n",
-			&conn->c_faddr,
-			RDS_PROTOCOL_MAJOR(conn->c_version),
-			RDS_PROTOCOL_MINOR(conn->c_version),
-			ic->i_flowctl ? ", flow control" : "");
+	if (conn->c_version < RDS_PROTOCOL(3,1)) {
+		printk(KERN_NOTICE "RDS/IB: Connection to %pI4 version %u.%u failed,"
+		       " no longer supported\n",
+		       &conn->c_faddr,
+		       RDS_PROTOCOL_MAJOR(conn->c_version),
+		       RDS_PROTOCOL_MINOR(conn->c_version));
+		rds_conn_destroy(conn);
+		return;
+	} else {
+		printk(KERN_NOTICE "RDS/IB: connected to %pI4 version %u.%u%s\n",
+		       &conn->c_faddr,
+		       RDS_PROTOCOL_MAJOR(conn->c_version),
+		       RDS_PROTOCOL_MINOR(conn->c_version),
+		       ic->i_flowctl ? ", flow control" : "");
+	}
 
 	/*
 	 * Init rings and fill recv. this needs to wait until protocol negotiation

net/rds/ib_recv.c

@@ -557,47 +557,6 @@ u64 rds_ib_piggyb_ack(struct rds_ib_connection *ic)
 	return rds_ib_get_ack(ic);
 }
 
-static struct rds_header *rds_ib_get_header(struct rds_connection *conn,
-					    struct rds_ib_recv_work *recv,
-					    u32 data_len)
-{
-	struct rds_ib_connection *ic = conn->c_transport_data;
-	void *hdr_buff = &ic->i_recv_hdrs[recv - ic->i_recvs];
-	void *addr;
-	u32 misplaced_hdr_bytes;
-
-	/*
-	 * Support header at the front (RDS 3.1+) as well as header-at-end.
-	 *
-	 * Cases:
-	 * 1) header all in header buff (great!)
-	 * 2) header all in data page (copy all to header buff)
-	 * 3) header split across hdr buf + data page
-	 *    (move bit in hdr buff to end before copying other bit from data page)
-	 */
-	if (conn->c_version > RDS_PROTOCOL_3_0 || data_len == RDS_FRAG_SIZE)
-	        return hdr_buff;
-
-	if (data_len <= (RDS_FRAG_SIZE - sizeof(struct rds_header))) {
-		addr = kmap_atomic(recv->r_frag->f_page, KM_SOFTIRQ0);
-		memcpy(hdr_buff,
-		       addr + recv->r_frag->f_offset + data_len,
-		       sizeof(struct rds_header));
-		kunmap_atomic(addr, KM_SOFTIRQ0);
-		return hdr_buff;
-	}
-
-	misplaced_hdr_bytes = (sizeof(struct rds_header) - (RDS_FRAG_SIZE - data_len));
-
-	memmove(hdr_buff + misplaced_hdr_bytes, hdr_buff, misplaced_hdr_bytes);
-
-	addr = kmap_atomic(recv->r_frag->f_page, KM_SOFTIRQ0);
-	memcpy(hdr_buff, addr + recv->r_frag->f_offset + data_len,
-	       sizeof(struct rds_header) - misplaced_hdr_bytes);
-	kunmap_atomic(addr, KM_SOFTIRQ0);
-	return hdr_buff;
-}
-
 /*
  * It's kind of lame that we're copying from the posted receive pages into
  * long-lived bitmaps.  We could have posted the bitmaps and rdma written into
@@ -710,7 +669,7 @@ static void rds_ib_process_recv(struct rds_connection *conn,
 	}
 	data_len -= sizeof(struct rds_header);
 
-	ihdr = rds_ib_get_header(conn, recv, data_len);
+	ihdr = &ic->i_recv_hdrs[recv - ic->i_recvs];
 
 	/* Validate the checksum. */
 	if (!rds_message_verify_checksum(ihdr)) {