RDS: Add TCP transport to RDS
This code allows RDS to be tunneled over a TCP connection.
RDMA operations are disabled when using TCP transport,
but this frees RDS from the IB/RDMA stack dependency, and allows
it to be used with standard Ethernet adapters, or in a VM.
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/tcp_send.c b/net/rds/tcp_send.c
new file mode 100644
index 0000000..ab545e0
--- /dev/null
+++ b/net/rds/tcp_send.c
@@ -0,0 +1,263 @@
+/*
+ * Copyright (c) 2006 Oracle. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/in.h>
+#include <net/tcp.h>
+
+#include "rds.h"
+#include "tcp.h"
+
+static void rds_tcp_cork(struct socket *sock, int val)
+{
+ mm_segment_t oldfs;
+
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ sock->ops->setsockopt(sock, SOL_TCP, TCP_CORK, (char __user *)&val,
+ sizeof(val));
+ set_fs(oldfs);
+}
+
+void rds_tcp_xmit_prepare(struct rds_connection *conn)
+{
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+
+ rds_tcp_cork(tc->t_sock, 1);
+}
+
+void rds_tcp_xmit_complete(struct rds_connection *conn)
+{
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+
+ rds_tcp_cork(tc->t_sock, 0);
+}
+
+/* the core send_sem serializes this with other xmit and shutdown */
+int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
+{
+ struct kvec vec = {
+ .iov_base = data,
+ .iov_len = len,
+ };
+ struct msghdr msg = {
+ .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL,
+ };
+
+ return kernel_sendmsg(sock, &msg, &vec, 1, vec.iov_len);
+}
+
+/* the core send_sem serializes this with other xmit and shutdown */
+int rds_tcp_xmit_cong_map(struct rds_connection *conn,
+ struct rds_cong_map *map, unsigned long offset)
+{
+ static struct rds_header rds_tcp_map_header = {
+ .h_flags = RDS_FLAG_CONG_BITMAP,
+ };
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+ unsigned long i;
+ int ret;
+ int copied = 0;
+
+ /* Some problem claims cpu_to_be32(constant) isn't a constant. */
+ rds_tcp_map_header.h_len = cpu_to_be32(RDS_CONG_MAP_BYTES);
+
+ if (offset < sizeof(struct rds_header)) {
+ ret = rds_tcp_sendmsg(tc->t_sock,
+ (void *)&rds_tcp_map_header + offset,
+ sizeof(struct rds_header) - offset);
+ if (ret <= 0)
+ return ret;
+ offset += ret;
+ copied = ret;
+ if (offset < sizeof(struct rds_header))
+ return ret;
+ }
+
+ offset -= sizeof(struct rds_header);
+ i = offset / PAGE_SIZE;
+ offset = offset % PAGE_SIZE;
+ BUG_ON(i >= RDS_CONG_MAP_PAGES);
+
+ do {
+ ret = tc->t_sock->ops->sendpage(tc->t_sock,
+ virt_to_page(map->m_page_addrs[i]),
+ offset, PAGE_SIZE - offset,
+ MSG_DONTWAIT);
+ if (ret <= 0)
+ break;
+ copied += ret;
+ offset += ret;
+ if (offset == PAGE_SIZE) {
+ offset = 0;
+ i++;
+ }
+ } while (i < RDS_CONG_MAP_PAGES);
+
+ return copied ? copied : ret;
+}
+
+/* the core send_sem serializes this with other xmit and shutdown */
+int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
+ unsigned int hdr_off, unsigned int sg, unsigned int off)
+{
+ struct rds_tcp_connection *tc = conn->c_transport_data;
+ int done = 0;
+ int ret = 0;
+
+ if (hdr_off == 0) {
+ /*
+ * m_ack_seq is set to the sequence number of the last byte of
+ * header and data. see rds_tcp_is_acked().
+ */
+ tc->t_last_sent_nxt = rds_tcp_snd_nxt(tc);
+ rm->m_ack_seq = tc->t_last_sent_nxt +
+ sizeof(struct rds_header) +
+ be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
+ smp_mb__before_clear_bit();
+ set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
+ tc->t_last_expected_una = rm->m_ack_seq + 1;
+
+ rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
+ rm, rds_tcp_snd_nxt(tc),
+ (unsigned long long)rm->m_ack_seq);
+ }
+
+ if (hdr_off < sizeof(struct rds_header)) {
+ /* see rds_tcp_write_space() */
+ set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
+
+ ret = rds_tcp_sendmsg(tc->t_sock,
+ (void *)&rm->m_inc.i_hdr + hdr_off,
+ sizeof(rm->m_inc.i_hdr) - hdr_off);
+ if (ret < 0)
+ goto out;
+ done += ret;
+ if (hdr_off + done != sizeof(struct rds_header))
+ goto out;
+ }
+
+ while (sg < rm->m_nents) {
+ ret = tc->t_sock->ops->sendpage(tc->t_sock,
+ sg_page(&rm->m_sg[sg]),
+ rm->m_sg[sg].offset + off,
+ rm->m_sg[sg].length - off,
+ MSG_DONTWAIT|MSG_NOSIGNAL);
+ rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->m_sg[sg]),
+ rm->m_sg[sg].offset + off, rm->m_sg[sg].length - off,
+ ret);
+ if (ret <= 0)
+ break;
+
+ off += ret;
+ done += ret;
+ if (off == rm->m_sg[sg].length) {
+ off = 0;
+ sg++;
+ }
+ }
+
+out:
+ if (ret <= 0) {
+ /* write_space will hit after EAGAIN, all else fatal */
+ if (ret == -EAGAIN) {
+ rds_tcp_stats_inc(s_tcp_sndbuf_full);
+ ret = 0;
+ } else {
+ printk(KERN_WARNING "RDS/tcp: send to %u.%u.%u.%u "
+ "returned %d, disconnecting and reconnecting\n",
+ NIPQUAD(conn->c_faddr), ret);
+ rds_conn_drop(conn);
+ }
+ }
+ if (done == 0)
+ done = ret;
+ return done;
+}
+
+/*
+ * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
+ * last byte of the message, including the header. This means that the
+ * entire message has been received if rm->m_ack_seq is "before" the next
+ * unacked byte of the TCP sequence space. We have to do very careful
+ * wrapping 32bit comparisons here.
+ */
+static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
+{
+ if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
+ return 0;
+ return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
+}
+
+void rds_tcp_write_space(struct sock *sk)
+{
+ void (*write_space)(struct sock *sk);
+ struct rds_connection *conn;
+ struct rds_tcp_connection *tc;
+
+ read_lock(&sk->sk_callback_lock);
+ conn = sk->sk_user_data;
+ if (conn == NULL) {
+ write_space = sk->sk_write_space;
+ goto out;
+ }
+
+ tc = conn->c_transport_data;
+ rdsdebug("write_space for tc %p\n", tc);
+ write_space = tc->t_orig_write_space;
+ rds_tcp_stats_inc(s_tcp_write_space_calls);
+
+ rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
+ tc->t_last_seen_una = rds_tcp_snd_una(tc);
+ rds_send_drop_acked(conn, rds_tcp_snd_una(tc), rds_tcp_is_acked);
+
+ queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+out:
+ read_unlock(&sk->sk_callback_lock);
+
+ /*
+ * write_space is only called when data leaves tcp's send queue if
+ * SOCK_NOSPACE is set. We set SOCK_NOSPACE every time we put
+ * data in tcp's send queue because we use write_space to parse the
+ * sequence numbers and notice that rds messages have been fully
+ * received.
+ *
+ * tcp's write_space clears SOCK_NOSPACE if the send queue has more
+ * than a certain amount of space. So we need to set it again *after*
+ * we call tcp's write_space or else we might only get called on the
+ * first of a series of incoming tcp acks.
+ */
+ write_space(sk);
+
+ if (sk->sk_socket)
+ set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+}