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>

1 files changed, 356 insertions, 0 deletions

diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
new file mode 100644
index 000000000000..c00dafffbb5a
--- /dev/null
+++ b/net/rds/tcp_recv.c
@@ -0,0 +1,356 @@
+/*
+ * 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 <net/tcp.h>
+
+#include "rds.h"
+#include "tcp.h"
+
+static struct kmem_cache *rds_tcp_incoming_slab;
+
+void rds_tcp_inc_purge(struct rds_incoming *inc)
+{
+	struct rds_tcp_incoming *tinc;
+	tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
+	rdsdebug("purging tinc %p inc %p\n", tinc, inc);
+	skb_queue_purge(&tinc->ti_skb_list);
+}
+
+void rds_tcp_inc_free(struct rds_incoming *inc)
+{
+	struct rds_tcp_incoming *tinc;
+	tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
+	rds_tcp_inc_purge(inc);
+	rdsdebug("freeing tinc %p inc %p\n", tinc, inc);
+	kmem_cache_free(rds_tcp_incoming_slab, tinc);
+}
+
+/*
+ * this is pretty lame, but, whatever.
+ */
+int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
+			     size_t size)
+{
+	struct rds_tcp_incoming *tinc;
+	struct iovec *iov, tmp;
+	struct sk_buff *skb;
+	unsigned long to_copy, skb_off;
+	int ret = 0;
+
+	if (size == 0)
+		goto out;
+
+	tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
+	iov = first_iov;
+	tmp = *iov;
+
+	skb_queue_walk(&tinc->ti_skb_list, skb) {
+		skb_off = 0;
+		while (skb_off < skb->len) {
+			while (tmp.iov_len == 0) {
+				iov++;
+				tmp = *iov;
+			}
+
+			to_copy = min(tmp.iov_len, size);
+			to_copy = min(to_copy, skb->len - skb_off);
+
+			rdsdebug("ret %d size %zu skb %p skb_off %lu "
+				 "skblen %d iov_base %p iov_len %zu cpy %lu\n",
+				 ret, size, skb, skb_off, skb->len,
+				 tmp.iov_base, tmp.iov_len, to_copy);
+
+			/* modifies tmp as it copies */
+			if (skb_copy_datagram_iovec(skb, skb_off, &tmp,
+						    to_copy)) {
+				ret = -EFAULT;
+				goto out;
+			}
+
+			size -= to_copy;
+			ret += to_copy;
+			skb_off += to_copy;
+			if (size == 0)
+				goto out;
+		}
+	}
+out:
+	return ret;
+}
+
+/*
+ * We have a series of skbs that have fragmented pieces of the congestion
+ * bitmap.  They must add up to the exact size of the congestion bitmap.  We
+ * use the skb helpers to copy those into the pages that make up the in-memory
+ * congestion bitmap for the remote address of this connection.  We then tell
+ * the congestion core that the bitmap has been changed so that it can wake up
+ * sleepers.
+ *
+ * This is racing with sending paths which are using test_bit to see if the
+ * bitmap indicates that their recipient is congested.
+ */
+
+static void rds_tcp_cong_recv(struct rds_connection *conn,
+			      struct rds_tcp_incoming *tinc)
+{
+	struct sk_buff *skb;
+	unsigned int to_copy, skb_off;
+	unsigned int map_off;
+	unsigned int map_page;
+	struct rds_cong_map *map;
+	int ret;
+
+	/* catch completely corrupt packets */
+	if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
+		return;
+
+	map_page = 0;
+	map_off = 0;
+	map = conn->c_fcong;
+
+	skb_queue_walk(&tinc->ti_skb_list, skb) {
+		skb_off = 0;
+		while (skb_off < skb->len) {
+			to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
+					skb->len - skb_off);
+
+			BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
+
+			/* only returns 0 or -error */
+			ret = skb_copy_bits(skb, skb_off,
+				(void *)map->m_page_addrs[map_page] + map_off,
+				to_copy);
+			BUG_ON(ret != 0);
+
+			skb_off += to_copy;
+			map_off += to_copy;
+			if (map_off == PAGE_SIZE) {
+				map_off = 0;
+				map_page++;
+			}
+		}
+	}
+
+	rds_cong_map_updated(map, ~(u64) 0);
+}
+
+struct rds_tcp_desc_arg {
+	struct rds_connection *conn;
+	gfp_t gfp;
+	enum km_type km;
+};
+
+static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
+			     unsigned int offset, size_t len)
+{
+	struct rds_tcp_desc_arg *arg = desc->arg.data;
+	struct rds_connection *conn = arg->conn;
+	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_incoming *tinc = tc->t_tinc;
+	struct sk_buff *clone;
+	size_t left = len, to_copy;
+
+	rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
+		 len);
+
+	/*
+	 * tcp_read_sock() interprets partial progress as an indication to stop
+	 * processing.
+	 */
+	while (left) {
+		if (tinc == NULL) {
+			tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
+					        arg->gfp);
+			if (tinc == NULL) {
+				desc->error = -ENOMEM;
+				goto out;
+			}
+			tc->t_tinc = tinc;
+			rdsdebug("alloced tinc %p\n", tinc);
+			rds_inc_init(&tinc->ti_inc, conn, conn->c_faddr);
+			/*
+			 * XXX * we might be able to use the __ variants when
+			 * we've already serialized at a higher level.
+			 */
+			skb_queue_head_init(&tinc->ti_skb_list);
+		}
+
+		if (left && tc->t_tinc_hdr_rem) {
+			to_copy = min(tc->t_tinc_hdr_rem, left);
+			rdsdebug("copying %zu header from skb %p\n", to_copy,
+				 skb);
+			skb_copy_bits(skb, offset,
+				      (char *)&tinc->ti_inc.i_hdr +
+						sizeof(struct rds_header) -
+						tc->t_tinc_hdr_rem,
+				      to_copy);
+			tc->t_tinc_hdr_rem -= to_copy;
+			left -= to_copy;
+			offset += to_copy;
+
+			if (tc->t_tinc_hdr_rem == 0) {
+				/* could be 0 for a 0 len message */
+				tc->t_tinc_data_rem =
+					be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
+			}
+		}
+
+		if (left && tc->t_tinc_data_rem) {
+			clone = skb_clone(skb, arg->gfp);
+			if (clone == NULL) {
+				desc->error = -ENOMEM;
+				goto out;
+			}
+
+			to_copy = min(tc->t_tinc_data_rem, left);
+			pskb_pull(clone, offset);
+			pskb_trim(clone, to_copy);
+			skb_queue_tail(&tinc->ti_skb_list, clone);
+
+			rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
+				 "clone %p data %p len %d\n",
+				 skb, skb->data, skb->len, offset, to_copy,
+				 clone, clone->data, clone->len);
+
+			tc->t_tinc_data_rem -= to_copy;
+			left -= to_copy;
+			offset += to_copy;
+		}
+
+		if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
+			if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
+				rds_tcp_cong_recv(conn, tinc);
+			else
+				rds_recv_incoming(conn, conn->c_faddr,
+						  conn->c_laddr, &tinc->ti_inc,
+						  arg->gfp, arg->km);
+
+			tc->t_tinc_hdr_rem = sizeof(struct rds_header);
+			tc->t_tinc_data_rem = 0;
+			tc->t_tinc = NULL;
+			rds_inc_put(&tinc->ti_inc);
+			tinc = NULL;
+		}
+	}
+out:
+	rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
+		 len, left, skb->len,
+		 skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
+	return len - left;
+}
+
+/* the caller has to hold the sock lock */
+int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp, enum km_type km)
+{
+	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct socket *sock = tc->t_sock;
+	read_descriptor_t desc;
+	struct rds_tcp_desc_arg arg;
+
+	/* It's like glib in the kernel! */
+	arg.conn = conn;
+	arg.gfp = gfp;
+	arg.km = km;
+	desc.arg.data = &arg;
+	desc.error = 0;
+	desc.count = 1; /* give more than one skb per call */
+
+	tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
+	rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
+		 desc.error);
+
+	return desc.error;
+}
+
+/*
+ * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
+ * data_ready.
+ *
+ * if we fail to allocate we're in trouble.. blindly wait some time before
+ * trying again to see if the VM can free up something for us.
+ */
+int rds_tcp_recv(struct rds_connection *conn)
+{
+	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct socket *sock = tc->t_sock;
+	int ret = 0;
+
+	rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
+
+	lock_sock(sock->sk);
+	ret = rds_tcp_read_sock(conn, GFP_KERNEL, KM_USER0);
+	release_sock(sock->sk);
+
+	return ret;
+}
+
+void rds_tcp_data_ready(struct sock *sk, int bytes)
+{
+	void (*ready)(struct sock *sk, int bytes);
+	struct rds_connection *conn;
+	struct rds_tcp_connection *tc;
+
+	rdsdebug("data ready sk %p bytes %d\n", sk, bytes);
+
+	read_lock(&sk->sk_callback_lock);
+	conn = sk->sk_user_data;
+	if (conn == NULL) { /* check for teardown race */
+		ready = sk->sk_data_ready;
+		goto out;
+	}
+
+	tc = conn->c_transport_data;
+	ready = tc->t_orig_data_ready;
+	rds_tcp_stats_inc(s_tcp_data_ready_calls);
+
+	if (rds_tcp_read_sock(conn, GFP_ATOMIC, KM_SOFTIRQ0) == -ENOMEM)
+		queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+out:
+	read_unlock(&sk->sk_callback_lock);
+	ready(sk, bytes);
+}
+
+int __init rds_tcp_recv_init(void)
+{
+	rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
+					sizeof(struct rds_tcp_incoming),
+					0, 0, NULL);
+	if (rds_tcp_incoming_slab == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void rds_tcp_recv_exit(void)
+{
+	kmem_cache_destroy(rds_tcp_incoming_slab);
+}