net/rds/tcp_send.c

   1 /*
   2  * Copyright (c) 2006 Oracle.  All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  *
  32  */
  33 #include <linux/kernel.h>
  34 #include <linux/in.h>
  35 #include <net/tcp.h>
  36
  37 #include "rds_single_path.h"
  38 #include "rds.h"
  39 #include "tcp.h"
  40
  41 static void rds_tcp_cork(struct socket *sock, int val)
  42 {
  43         mm_segment_t oldfs;
  44
  45         oldfs = get_fs();
  46         set_fs(KERNEL_DS);
  47         sock->ops->setsockopt(sock, SOL_TCP, TCP_CORK, (char __user *)&val,
  48                               sizeof(val));
  49         set_fs(oldfs);
  50 }
  51
  52 void rds_tcp_xmit_path_prepare(struct rds_conn_path *cp)
  53 {
  54         struct rds_tcp_connection *tc = cp->cp_transport_data;
  55
  56         rds_tcp_cork(tc->t_sock, 1);
  57 }
  58
  59 void rds_tcp_xmit_path_complete(struct rds_conn_path *cp)
  60 {
  61         struct rds_tcp_connection *tc = cp->cp_transport_data;
  62
  63         rds_tcp_cork(tc->t_sock, 0);
  64 }
  65
  66 /* the core send_sem serializes this with other xmit and shutdown */
  67 static int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
  68 {
  69         struct kvec vec = {
  70                 .iov_base = data,
  71                 .iov_len = len,
  72         };
  73         struct msghdr msg = {
  74                 .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL,
  75         };
  76
  77         return kernel_sendmsg(sock, &msg, &vec, 1, vec.iov_len);
  78 }
  79
  80 /* the core send_sem serializes this with other xmit and shutdown */
  81 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
  82                  unsigned int hdr_off, unsigned int sg, unsigned int off)
  83 {
  84         struct rds_conn_path *cp = rm->m_inc.i_conn_path;
  85         struct rds_tcp_connection *tc = cp->cp_transport_data;
  86         int done = 0;
  87         int ret = 0;
  88         int more;
  89
  90         if (hdr_off == 0) {
  91                 /*
  92                  * m_ack_seq is set to the sequence number of the last byte of
  93                  * header and data.  see rds_tcp_is_acked().
  94                  */
  95                 tc->t_last_sent_nxt = rds_tcp_snd_nxt(tc);
  96                 rm->m_ack_seq = tc->t_last_sent_nxt +
  97                                 sizeof(struct rds_header) +
  98                                 be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
  99                 smp_mb__before_atomic();
 100                 set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
 101                 tc->t_last_expected_una = rm->m_ack_seq + 1;
 102
 103                 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
 104                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
 105
 106                 rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
 107                          rm, rds_tcp_snd_nxt(tc),
 108                          (unsigned long long)rm->m_ack_seq);
 109         }
 110
 111         if (hdr_off < sizeof(struct rds_header)) {
 112                 /* see rds_tcp_write_space() */
 113                 set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
 114
 115                 ret = rds_tcp_sendmsg(tc->t_sock,
 116                                       (void *)&rm->m_inc.i_hdr + hdr_off,
 117                                       sizeof(rm->m_inc.i_hdr) - hdr_off);
 118                 if (ret < 0)
 119                         goto out;
 120                 done += ret;
 121                 if (hdr_off + done != sizeof(struct rds_header))
 122                         goto out;
 123         }
 124
 125         more = rm->data.op_nents > 1 ? (MSG_MORE | MSG_SENDPAGE_NOTLAST) : 0;
 126         while (sg < rm->data.op_nents) {
 127                 int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more;
 128
 129                 ret = tc->t_sock->ops->sendpage(tc->t_sock,
 130                                                 sg_page(&rm->data.op_sg[sg]),
 131                                                 rm->data.op_sg[sg].offset + off,
 132                                                 rm->data.op_sg[sg].length - off,
 133                                                 flags);
 134                 rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]),
 135                          rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off,
 136                          ret);
 137                 if (ret <= 0)
 138                         break;
 139
 140                 off += ret;
 141                 done += ret;
 142                 if (off == rm->data.op_sg[sg].length) {
 143                         off = 0;
 144                         sg++;
 145                 }
 146                 if (sg == rm->data.op_nents - 1)
 147                         more = 0;
 148         }
 149
 150 out:
 151         if (ret <= 0) {
 152                 /* write_space will hit after EAGAIN, all else fatal */
 153                 if (ret == -EAGAIN) {
 154                         rds_tcp_stats_inc(s_tcp_sndbuf_full);
 155                         ret = 0;
 156                 } else {
 157                         /* No need to disconnect/reconnect if path_drop
 158                          * has already been triggered, because, e.g., of
 159                          * an incoming RST.
 160                          */
 161                         if (rds_conn_path_up(cp)) {
 162                                 pr_warn("RDS/tcp: send to %pI4 on cp [%d]"
 163                                         "returned %d, "
 164                                         "disconnecting and reconnecting\n",
 165                                         &conn->c_faddr, cp->cp_index, ret);
 166                                 rds_conn_path_drop(cp);
 167                         }
 168                 }
 169         }
 170         if (done == 0)
 171                 done = ret;
 172         return done;
 173 }
 174
 175 /*
 176  * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
 177  * last byte of the message, including the header.  This means that the
 178  * entire message has been received if rm->m_ack_seq is "before" the next
 179  * unacked byte of the TCP sequence space.  We have to do very careful
 180  * wrapping 32bit comparisons here.
 181  */
 182 static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
 183 {
 184         if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
 185                 return 0;
 186         return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
 187 }
 188
 189 void rds_tcp_write_space(struct sock *sk)
 190 {
 191         void (*write_space)(struct sock *sk);
 192         struct rds_conn_path *cp;
 193         struct rds_tcp_connection *tc;
 194
 195         read_lock_bh(&sk->sk_callback_lock);
 196         cp = sk->sk_user_data;
 197         if (!cp) {
 198                 write_space = sk->sk_write_space;
 199                 goto out;
 200         }
 201
 202         tc = cp->cp_transport_data;
 203         rdsdebug("write_space for tc %p\n", tc);
 204         write_space = tc->t_orig_write_space;
 205         rds_tcp_stats_inc(s_tcp_write_space_calls);
 206
 207         rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
 208         tc->t_last_seen_una = rds_tcp_snd_una(tc);
 209         rds_send_path_drop_acked(cp, rds_tcp_snd_una(tc), rds_tcp_is_acked);
 210
 211         if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf)
 212                 queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
 213
 214 out:
 215         read_unlock_bh(&sk->sk_callback_lock);
 216
 217         /*
 218          * write_space is only called when data leaves tcp's send queue if
 219          * SOCK_NOSPACE is set.  We set SOCK_NOSPACE every time we put
 220          * data in tcp's send queue because we use write_space to parse the
 221          * sequence numbers and notice that rds messages have been fully
 222          * received.
 223          *
 224          * tcp's write_space clears SOCK_NOSPACE if the send queue has more
 225          * than a certain amount of space. So we need to set it again *after*
 226          * we call tcp's write_space or else we might only get called on the
 227          * first of a series of incoming tcp acks.
 228          */
 229         write_space(sk);
 230
 231         if (sk->sk_socket)
 232                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 233 }