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);
+}