git.oblomov.eu Git - linux-2.6/blob - fs/dlm/lowcomms.c

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
   6 **
   7 **  This copyrighted material is made available to anyone wishing to use,
   8 **  modify, copy, or redistribute it subject to the terms and conditions
   9 **  of the GNU General Public License v.2.
  10 **
  11 *******************************************************************************
  12 ******************************************************************************/
  13
  14 /*
  15  * lowcomms.c
  16  *
  17  * This is the "low-level" comms layer.
  18  *
  19  * It is responsible for sending/receiving messages
  20  * from other nodes in the cluster.
  21  *
  22  * Cluster nodes are referred to by their nodeids. nodeids are
  23  * simply 32 bit numbers to the locking module - if they need to
  24  * be expanded for the cluster infrastructure then that is it's
  25  * responsibility. It is this layer's
  26  * responsibility to resolve these into IP address or
  27  * whatever it needs for inter-node communication.
  28  *
  29  * The comms level is two kernel threads that deal mainly with
  30  * the receiving of messages from other nodes and passing them
  31  * up to the mid-level comms layer (which understands the
  32  * message format) for execution by the locking core, and
  33  * a send thread which does all the setting up of connections
  34  * to remote nodes and the sending of data. Threads are not allowed
  35  * to send their own data because it may cause them to wait in times
  36  * of high load. Also, this way, the sending thread can collect together
  37  * messages bound for one node and send them in one block.
  38  *
  39  * lowcomms will choose to use wither TCP or SCTP as its transport layer
  40  * depending on the configuration variable 'protocol'. This should be set
  41  * to 0 (default) for TCP or 1 for SCTP. It shouldbe configured using a
  42  * cluster-wide mechanism as it must be the same on all nodes of the cluster
  43  * for the DLM to function.
  44  *
  45  */
  46
  47 #include <asm/ioctls.h>
  48 #include <net/sock.h>
  49 #include <net/tcp.h>
  50 #include <linux/pagemap.h>
  51 #include <linux/idr.h>
  52 #include <linux/file.h>
  53 #include <linux/sctp.h>
  54 #include <net/sctp/user.h>
  55
  56 #include "dlm_internal.h"
  57 #include "lowcomms.h"
  58 #include "midcomms.h"
  59 #include "config.h"
  60
  61 #define NEEDED_RMEM (4*1024*1024)
  62
  63 struct cbuf {
  64         unsigned int base;
  65         unsigned int len;
  66         unsigned int mask;
  67 };
  68
  69 static void cbuf_add(struct cbuf *cb, int n)
  70 {
  71         cb->len += n;
  72 }
  73
  74 static int cbuf_data(struct cbuf *cb)
  75 {
  76         return ((cb->base + cb->len) & cb->mask);
  77 }
  78
  79 static void cbuf_init(struct cbuf *cb, int size)
  80 {
  81         cb->base = cb->len = 0;
  82         cb->mask = size-1;
  83 }
  84
  85 static void cbuf_eat(struct cbuf *cb, int n)
  86 {
  87         cb->len  -= n;
  88         cb->base += n;
  89         cb->base &= cb->mask;
  90 }
  91
  92 static bool cbuf_empty(struct cbuf *cb)
  93 {
  94         return cb->len == 0;
  95 }
  96
  97 struct connection {
  98         struct socket *sock;    /* NULL if not connected */
  99         uint32_t nodeid;        /* So we know who we are in the list */
 100         struct mutex sock_mutex;
 101         unsigned long flags;
 102 #define CF_READ_PENDING 1
 103 #define CF_WRITE_PENDING 2
 104 #define CF_CONNECT_PENDING 3
 105 #define CF_INIT_PENDING 4
 106 #define CF_IS_OTHERCON 5
 107         struct list_head writequeue;  /* List of outgoing writequeue_entries */
 108         spinlock_t writequeue_lock;
 109         int (*rx_action) (struct connection *); /* What to do when active */
 110         void (*connect_action) (struct connection *);   /* What to do to connect */
 111         struct page *rx_page;
 112         struct cbuf cb;
 113         int retries;
 114 #define MAX_CONNECT_RETRIES 3
 115         int sctp_assoc;
 116         struct connection *othercon;
 117         struct work_struct rwork; /* Receive workqueue */
 118         struct work_struct swork; /* Send workqueue */
 119 };
 120 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
 121
 122 /* An entry waiting to be sent */
 123 struct writequeue_entry {
 124         struct list_head list;
 125         struct page *page;
 126         int offset;
 127         int len;
 128         int end;
 129         int users;
 130         struct connection *con;
 131 };
 132
 133 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 134 static int dlm_local_count;
 135
 136 /* Work queues */
 137 static struct workqueue_struct *recv_workqueue;
 138 static struct workqueue_struct *send_workqueue;
 139
 140 static DEFINE_IDR(connections_idr);
 141 static DECLARE_MUTEX(connections_lock);
 142 static int max_nodeid;
 143 static struct kmem_cache *con_cache;
 144
 145 static void process_recv_sockets(struct work_struct *work);
 146 static void process_send_sockets(struct work_struct *work);
 147
 148 /*
 149  * If 'allocation' is zero then we don't attempt to create a new
 150  * connection structure for this node.
 151  */
 152 static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
 153 {
 154         struct connection *con = NULL;
 155         int r;
 156         int n;
 157
 158         con = idr_find(&connections_idr, nodeid);
 159         if (con || !alloc)
 160                 return con;
 161
 162         r = idr_pre_get(&connections_idr, alloc);
 163         if (!r)
 164                 return NULL;
 165
 166         con = kmem_cache_zalloc(con_cache, alloc);
 167         if (!con)
 168                 return NULL;
 169
 170         r = idr_get_new_above(&connections_idr, con, nodeid, &n);
 171         if (r) {
 172                 kmem_cache_free(con_cache, con);
 173                 return NULL;
 174         }
 175
 176         if (n != nodeid) {
 177                 idr_remove(&connections_idr, n);
 178                 kmem_cache_free(con_cache, con);
 179                 return NULL;
 180         }
 181
 182         con->nodeid = nodeid;
 183         mutex_init(&con->sock_mutex);
 184         INIT_LIST_HEAD(&con->writequeue);
 185         spin_lock_init(&con->writequeue_lock);
 186         INIT_WORK(&con->swork, process_send_sockets);
 187         INIT_WORK(&con->rwork, process_recv_sockets);
 188
 189         /* Setup action pointers for child sockets */
 190         if (con->nodeid) {
 191                 struct connection *zerocon = idr_find(&connections_idr, 0);
 192
 193                 con->connect_action = zerocon->connect_action;
 194                 if (!con->rx_action)
 195                         con->rx_action = zerocon->rx_action;
 196         }
 197
 198         if (nodeid > max_nodeid)
 199                 max_nodeid = nodeid;
 200
 201         return con;
 202 }
 203
 204 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
 205 {
 206         struct connection *con;
 207
 208         down(&connections_lock);
 209         con = __nodeid2con(nodeid, allocation);
 210         up(&connections_lock);
 211
 212         return con;
 213 }
 214
 215 /* This is a bit drastic, but only called when things go wrong */
 216 static struct connection *assoc2con(int assoc_id)
 217 {
 218         int i;
 219         struct connection *con;
 220
 221         down(&connections_lock);
 222         for (i=0; i<=max_nodeid; i++) {
 223                 con = __nodeid2con(i, 0);
 224                 if (con && con->sctp_assoc == assoc_id) {
 225                         up(&connections_lock);
 226                         return con;
 227                 }
 228         }
 229         up(&connections_lock);
 230         return NULL;
 231 }
 232
 233 static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
 234 {
 235         struct sockaddr_storage addr;
 236         int error;
 237
 238         if (!dlm_local_count)
 239                 return -1;
 240
 241         error = dlm_nodeid_to_addr(nodeid, &addr);
 242         if (error)
 243                 return error;
 244
 245         if (dlm_local_addr[0]->ss_family == AF_INET) {
 246                 struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
 247                 struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
 248                 ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
 249         } else {
 250                 struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
 251                 struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
 252                 memcpy(&ret6->sin6_addr, &in6->sin6_addr,
 253                        sizeof(in6->sin6_addr));
 254         }
 255
 256         return 0;
 257 }
 258
 259 /* Data available on socket or listen socket received a connect */
 260 static void lowcomms_data_ready(struct sock *sk, int count_unused)
 261 {
 262         struct connection *con = sock2con(sk);
 263         if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
 264                 queue_work(recv_workqueue, &con->rwork);
 265 }
 266
 267 static void lowcomms_write_space(struct sock *sk)
 268 {
 269         struct connection *con = sock2con(sk);
 270
 271         if (con && !test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 272                 queue_work(send_workqueue, &con->swork);
 273 }
 274
 275 static inline void lowcomms_connect_sock(struct connection *con)
 276 {
 277         if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
 278                 queue_work(send_workqueue, &con->swork);
 279 }
 280
 281 static void lowcomms_state_change(struct sock *sk)
 282 {
 283         if (sk->sk_state == TCP_ESTABLISHED)
 284                 lowcomms_write_space(sk);
 285 }
 286
 287 /* Make a socket active */
 288 static int add_sock(struct socket *sock, struct connection *con)
 289 {
 290         con->sock = sock;
 291
 292         /* Install a data_ready callback */
 293         con->sock->sk->sk_data_ready = lowcomms_data_ready;
 294         con->sock->sk->sk_write_space = lowcomms_write_space;
 295         con->sock->sk->sk_state_change = lowcomms_state_change;
 296         con->sock->sk->sk_user_data = con;
 297         return 0;
 298 }
 299
 300 /* Add the port number to an IPv6 or 4 sockaddr and return the address
 301    length */
 302 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 303                           int *addr_len)
 304 {
 305         saddr->ss_family =  dlm_local_addr[0]->ss_family;
 306         if (saddr->ss_family == AF_INET) {
 307                 struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
 308                 in4_addr->sin_port = cpu_to_be16(port);
 309                 *addr_len = sizeof(struct sockaddr_in);
 310                 memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
 311         } else {
 312                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
 313                 in6_addr->sin6_port = cpu_to_be16(port);
 314                 *addr_len = sizeof(struct sockaddr_in6);
 315         }
 316 }
 317
 318 /* Close a remote connection and tidy up */
 319 static void close_connection(struct connection *con, bool and_other)
 320 {
 321         mutex_lock(&con->sock_mutex);
 322
 323         if (con->sock) {
 324                 sock_release(con->sock);
 325                 con->sock = NULL;
 326         }
 327         if (con->othercon && and_other) {
 328                 /* Will only re-enter once. */
 329                 close_connection(con->othercon, false);
 330         }
 331         if (con->rx_page) {
 332                 __free_page(con->rx_page);
 333                 con->rx_page = NULL;
 334         }
 335         con->retries = 0;
 336         mutex_unlock(&con->sock_mutex);
 337 }
 338
 339 /* We only send shutdown messages to nodes that are not part of the cluster */
 340 static void sctp_send_shutdown(sctp_assoc_t associd)
 341 {
 342         static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 343         struct msghdr outmessage;
 344         struct cmsghdr *cmsg;
 345         struct sctp_sndrcvinfo *sinfo;
 346         int ret;
 347         struct connection *con;
 348
 349         con = nodeid2con(0,0);
 350         BUG_ON(con == NULL);
 351
 352         outmessage.msg_name = NULL;
 353         outmessage.msg_namelen = 0;
 354         outmessage.msg_control = outcmsg;
 355         outmessage.msg_controllen = sizeof(outcmsg);
 356         outmessage.msg_flags = MSG_EOR;
 357
 358         cmsg = CMSG_FIRSTHDR(&outmessage);
 359         cmsg->cmsg_level = IPPROTO_SCTP;
 360         cmsg->cmsg_type = SCTP_SNDRCV;
 361         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 362         outmessage.msg_controllen = cmsg->cmsg_len;
 363         sinfo = CMSG_DATA(cmsg);
 364         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 365
 366         sinfo->sinfo_flags |= MSG_EOF;
 367         sinfo->sinfo_assoc_id = associd;
 368
 369         ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);
 370
 371         if (ret != 0)
 372                 log_print("send EOF to node failed: %d", ret);
 373 }
 374
 375 /* INIT failed but we don't know which node...
 376    restart INIT on all pending nodes */
 377 static void sctp_init_failed(void)
 378 {
 379         int i;
 380         struct connection *con;
 381
 382         down(&connections_lock);
 383         for (i=1; i<=max_nodeid; i++) {
 384                 con = __nodeid2con(i, 0);
 385                 if (!con)
 386                         continue;
 387                 con->sctp_assoc = 0;
 388                 if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
 389                         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
 390                                 queue_work(send_workqueue, &con->swork);
 391                         }
 392                 }
 393         }
 394         up(&connections_lock);
 395 }
 396
 397 /* Something happened to an association */
 398 static void process_sctp_notification(struct connection *con,
 399                                       struct msghdr *msg, char *buf)
 400 {
 401         union sctp_notification *sn = (union sctp_notification *)buf;
 402
 403         if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
 404                 switch (sn->sn_assoc_change.sac_state) {
 405
 406                 case SCTP_COMM_UP:
 407                 case SCTP_RESTART:
 408                 {
 409                         /* Check that the new node is in the lockspace */
 410                         struct sctp_prim prim;
 411                         int nodeid;
 412                         int prim_len, ret;
 413                         int addr_len;
 414                         struct connection *new_con;
 415                         struct file *file;
 416                         sctp_peeloff_arg_t parg;
 417                         int parglen = sizeof(parg);
 418
 419                         /*
 420                          * We get this before any data for an association.
 421                          * We verify that the node is in the cluster and
 422                          * then peel off a socket for it.
 423                          */
 424                         if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
 425                                 log_print("COMM_UP for invalid assoc ID %d",
 426                                          (int)sn->sn_assoc_change.sac_assoc_id);
 427                                 sctp_init_failed();
 428                                 return;
 429                         }
 430                         memset(&prim, 0, sizeof(struct sctp_prim));
 431                         prim_len = sizeof(struct sctp_prim);
 432                         prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
 433
 434                         ret = kernel_getsockopt(con->sock,
 435                                                 IPPROTO_SCTP,
 436                                                 SCTP_PRIMARY_ADDR,
 437                                                 (char*)&prim,
 438                                                 &prim_len);
 439                         if (ret < 0) {
 440                                 log_print("getsockopt/sctp_primary_addr on "
 441                                           "new assoc %d failed : %d",
 442                                           (int)sn->sn_assoc_change.sac_assoc_id,
 443                                           ret);
 444
 445                                 /* Retry INIT later */
 446                                 new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 447                                 if (new_con)
 448                                         clear_bit(CF_CONNECT_PENDING, &con->flags);
 449                                 return;
 450                         }
 451                         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
 452                         if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
 453                                 int i;
 454                                 unsigned char *b=(unsigned char *)&prim.ssp_addr;
 455                                 log_print("reject connect from unknown addr");
 456                                 for (i=0; i<sizeof(struct sockaddr_storage);i++)
 457                                         printk("%02x ", b[i]);
 458                                 printk("\n");
 459                                 sctp_send_shutdown(prim.ssp_assoc_id);
 460                                 return;
 461                         }
 462
 463                         new_con = nodeid2con(nodeid, GFP_KERNEL);
 464                         if (!new_con)
 465                                 return;
 466
 467                         /* Peel off a new sock */
 468                         parg.associd = sn->sn_assoc_change.sac_assoc_id;
 469                         ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
 470                                                 SCTP_SOCKOPT_PEELOFF,
 471                                                 (void *)&parg, &parglen);
 472                         if (ret) {
 473                                 log_print("Can't peel off a socket for "
 474                                           "connection %d to node %d: err=%d\n",
 475                                           parg.associd, nodeid, ret);
 476                         }
 477                         file = fget(parg.sd);
 478                         new_con->sock = SOCKET_I(file->f_dentry->d_inode);
 479                         add_sock(new_con->sock, new_con);
 480                         fput(file);
 481                         put_unused_fd(parg.sd);
 482
 483                         log_print("got new/restarted association %d nodeid %d",
 484                                  (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
 485
 486                         /* Send any pending writes */
 487                         clear_bit(CF_CONNECT_PENDING, &new_con->flags);
 488                         clear_bit(CF_INIT_PENDING, &con->flags);
 489                         if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
 490                                 queue_work(send_workqueue, &new_con->swork);
 491                         }
 492                         if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))
 493                                 queue_work(recv_workqueue, &new_con->rwork);
 494                 }
 495                 break;
 496
 497                 case SCTP_COMM_LOST:
 498                 case SCTP_SHUTDOWN_COMP:
 499                 {
 500                         con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 501                         if (con) {
 502                                 con->sctp_assoc = 0;
 503                         }
 504                 }
 505                 break;
 506
 507                 /* We don't know which INIT failed, so clear the PENDING flags
 508                  * on them all.  if assoc_id is zero then it will then try
 509                  * again */
 510
 511                 case SCTP_CANT_STR_ASSOC:
 512                 {
 513                         log_print("Can't start SCTP association - retrying");
 514                         sctp_init_failed();
 515                 }
 516                 break;
 517
 518                 default:
 519                         log_print("unexpected SCTP assoc change id=%d state=%d",
 520                                   (int)sn->sn_assoc_change.sac_assoc_id,
 521                                   sn->sn_assoc_change.sac_state);
 522                 }
 523         }
 524 }
 525
 526 /* Data received from remote end */
 527 static int receive_from_sock(struct connection *con)
 528 {
 529         int ret = 0;
 530         struct msghdr msg = {};
 531         struct kvec iov[2];
 532         unsigned len;
 533         int r;
 534         int call_again_soon = 0;
 535         int nvec;
 536         char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 537
 538         mutex_lock(&con->sock_mutex);
 539
 540         if (con->sock == NULL) {
 541                 ret = -EAGAIN;
 542                 goto out_close;
 543         }
 544
 545         if (con->rx_page == NULL) {
 546                 /*
 547                  * This doesn't need to be atomic, but I think it should
 548                  * improve performance if it is.
 549                  */
 550                 con->rx_page = alloc_page(GFP_ATOMIC);
 551                 if (con->rx_page == NULL)
 552                         goto out_resched;
 553                 cbuf_init(&con->cb, PAGE_CACHE_SIZE);
 554         }
 555
 556         /* Only SCTP needs these really */
 557         memset(&incmsg, 0, sizeof(incmsg));
 558         msg.msg_control = incmsg;
 559         msg.msg_controllen = sizeof(incmsg);
 560
 561         /*
 562          * iov[0] is the bit of the circular buffer between the current end
 563          * point (cb.base + cb.len) and the end of the buffer.
 564          */
 565         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
 566         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
 567         iov[1].iov_len = 0;
 568         nvec = 1;
 569
 570         /*
 571          * iov[1] is the bit of the circular buffer between the start of the
 572          * buffer and the start of the currently used section (cb.base)
 573          */
 574         if (cbuf_data(&con->cb) >= con->cb.base) {
 575                 iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
 576                 iov[1].iov_len = con->cb.base;
 577                 iov[1].iov_base = page_address(con->rx_page);
 578                 nvec = 2;
 579         }
 580         len = iov[0].iov_len + iov[1].iov_len;
 581
 582         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
 583                                MSG_DONTWAIT | MSG_NOSIGNAL);
 584         if (ret <= 0)
 585                 goto out_close;
 586
 587         /* Process SCTP notifications */
 588         if (msg.msg_flags & MSG_NOTIFICATION) {
 589                 msg.msg_control = incmsg;
 590                 msg.msg_controllen = sizeof(incmsg);
 591
 592                 process_sctp_notification(con, &msg,
 593                                 page_address(con->rx_page) + con->cb.base);
 594                 mutex_unlock(&con->sock_mutex);
 595                 return 0;
 596         }
 597         BUG_ON(con->nodeid == 0);
 598
 599         if (ret == len)
 600                 call_again_soon = 1;
 601         cbuf_add(&con->cb, ret);
 602         ret = dlm_process_incoming_buffer(con->nodeid,
 603                                           page_address(con->rx_page),
 604                                           con->cb.base, con->cb.len,
 605                                           PAGE_CACHE_SIZE);
 606         if (ret == -EBADMSG) {
 607                 log_print("lowcomms: addr=%p, base=%u, len=%u, "
 608                           "iov_len=%u, iov_base[0]=%p, read=%d",
 609                           page_address(con->rx_page), con->cb.base, con->cb.len,
 610                           len, iov[0].iov_base, r);
 611         }
 612         if (ret < 0)
 613                 goto out_close;
 614         cbuf_eat(&con->cb, ret);
 615
 616         if (cbuf_empty(&con->cb) && !call_again_soon) {
 617                 __free_page(con->rx_page);
 618                 con->rx_page = NULL;
 619         }
 620
 621         if (call_again_soon)
 622                 goto out_resched;
 623         mutex_unlock(&con->sock_mutex);
 624         return 0;
 625
 626 out_resched:
 627         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
 628                 queue_work(recv_workqueue, &con->rwork);
 629         mutex_unlock(&con->sock_mutex);
 630         return -EAGAIN;
 631
 632 out_close:
 633         mutex_unlock(&con->sock_mutex);
 634         if (ret != -EAGAIN && !test_bit(CF_IS_OTHERCON, &con->flags)) {
 635                 close_connection(con, false);
 636                 /* Reconnect when there is something to send */
 637         }
 638         /* Don't return success if we really got EOF */
 639         if (ret == 0)
 640                 ret = -EAGAIN;
 641
 642         return ret;
 643 }
 644
 645 /* Listening socket is busy, accept a connection */
 646 static int tcp_accept_from_sock(struct connection *con)
 647 {
 648         int result;
 649         struct sockaddr_storage peeraddr;
 650         struct socket *newsock;
 651         int len;
 652         int nodeid;
 653         struct connection *newcon;
 654         struct connection *addcon;
 655
 656         memset(&peeraddr, 0, sizeof(peeraddr));
 657         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 658                                   IPPROTO_TCP, &newsock);
 659         if (result < 0)
 660                 return -ENOMEM;
 661
 662         mutex_lock_nested(&con->sock_mutex, 0);
 663
 664         result = -ENOTCONN;
 665         if (con->sock == NULL)
 666                 goto accept_err;
 667
 668         newsock->type = con->sock->type;
 669         newsock->ops = con->sock->ops;
 670
 671         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
 672         if (result < 0)
 673                 goto accept_err;
 674
 675         /* Get the connected socket's peer */
 676         memset(&peeraddr, 0, sizeof(peeraddr));
 677         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
 678                                   &len, 2)) {
 679                 result = -ECONNABORTED;
 680                 goto accept_err;
 681         }
 682
 683         /* Get the new node's NODEID */
 684         make_sockaddr(&peeraddr, 0, &len);
 685         if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
 686                 log_print("connect from non cluster node");
 687                 sock_release(newsock);
 688                 mutex_unlock(&con->sock_mutex);
 689                 return -1;
 690         }
 691
 692         log_print("got connection from %d", nodeid);
 693
 694         /*  Check to see if we already have a connection to this node. This
 695          *  could happen if the two nodes initiate a connection at roughly
 696          *  the same time and the connections cross on the wire.
 697          *  In this case we store the incoming one in "othercon"
 698          */
 699         newcon = nodeid2con(nodeid, GFP_KERNEL);
 700         if (!newcon) {
 701                 result = -ENOMEM;
 702                 goto accept_err;
 703         }
 704         mutex_lock_nested(&newcon->sock_mutex, 1);
 705         if (newcon->sock) {
 706                 struct connection *othercon = newcon->othercon;
 707
 708                 if (!othercon) {
 709                         othercon = kmem_cache_zalloc(con_cache, GFP_KERNEL);
 710                         if (!othercon) {
 711                                 log_print("failed to allocate incoming socket");
 712                                 mutex_unlock(&newcon->sock_mutex);
 713                                 result = -ENOMEM;
 714                                 goto accept_err;
 715                         }
 716                         othercon->nodeid = nodeid;
 717                         othercon->rx_action = receive_from_sock;
 718                         mutex_init(&othercon->sock_mutex);
 719                         INIT_WORK(&othercon->swork, process_send_sockets);
 720                         INIT_WORK(&othercon->rwork, process_recv_sockets);
 721                         set_bit(CF_IS_OTHERCON, &othercon->flags);
 722                         newcon->othercon = othercon;
 723                         othercon->sock = newsock;
 724                         newsock->sk->sk_user_data = othercon;
 725                         add_sock(newsock, othercon);
 726                         addcon = othercon;
 727                 }
 728                 else {
 729                         printk("Extra connection from node %d attempted\n", nodeid);
 730                         result = -EAGAIN;
 731                         mutex_unlock(&newcon->sock_mutex);
 732                         goto accept_err;
 733                 }
 734         }
 735         else {
 736                 newsock->sk->sk_user_data = newcon;
 737                 newcon->rx_action = receive_from_sock;
 738                 add_sock(newsock, newcon);
 739                 addcon = newcon;
 740         }
 741
 742         mutex_unlock(&newcon->sock_mutex);
 743
 744         /*
 745          * Add it to the active queue in case we got data
 746          * beween processing the accept adding the socket
 747          * to the read_sockets list
 748          */
 749         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
 750                 queue_work(recv_workqueue, &addcon->rwork);
 751         mutex_unlock(&con->sock_mutex);
 752
 753         return 0;
 754
 755 accept_err:
 756         mutex_unlock(&con->sock_mutex);
 757         sock_release(newsock);
 758
 759         if (result != -EAGAIN)
 760                 log_print("error accepting connection from node: %d", result);
 761         return result;
 762 }
 763
 764 static void free_entry(struct writequeue_entry *e)
 765 {
 766         __free_page(e->page);
 767         kfree(e);
 768 }
 769
 770 /* Initiate an SCTP association.
 771    This is a special case of send_to_sock() in that we don't yet have a
 772    peeled-off socket for this association, so we use the listening socket
 773    and add the primary IP address of the remote node.
 774  */
 775 static void sctp_init_assoc(struct connection *con)
 776 {
 777         struct sockaddr_storage rem_addr;
 778         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 779         struct msghdr outmessage;
 780         struct cmsghdr *cmsg;
 781         struct sctp_sndrcvinfo *sinfo;
 782         struct connection *base_con;
 783         struct writequeue_entry *e;
 784         int len, offset;
 785         int ret;
 786         int addrlen;
 787         struct kvec iov[1];
 788
 789         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
 790                 return;
 791
 792         if (con->retries++ > MAX_CONNECT_RETRIES)
 793                 return;
 794
 795         log_print("Initiating association with node %d", con->nodeid);
 796
 797         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
 798                 log_print("no address for nodeid %d", con->nodeid);
 799                 return;
 800         }
 801         base_con = nodeid2con(0, 0);
 802         BUG_ON(base_con == NULL);
 803
 804         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
 805
 806         outmessage.msg_name = &rem_addr;
 807         outmessage.msg_namelen = addrlen;
 808         outmessage.msg_control = outcmsg;
 809         outmessage.msg_controllen = sizeof(outcmsg);
 810         outmessage.msg_flags = MSG_EOR;
 811
 812         spin_lock(&con->writequeue_lock);
 813         e = list_entry(con->writequeue.next, struct writequeue_entry,
 814                        list);
 815
 816         BUG_ON((struct list_head *) e == &con->writequeue);
 817
 818         len = e->len;
 819         offset = e->offset;
 820         spin_unlock(&con->writequeue_lock);
 821         kmap(e->page);
 822
 823         /* Send the first block off the write queue */
 824         iov[0].iov_base = page_address(e->page)+offset;
 825         iov[0].iov_len = len;
 826
 827         cmsg = CMSG_FIRSTHDR(&outmessage);
 828         cmsg->cmsg_level = IPPROTO_SCTP;
 829         cmsg->cmsg_type = SCTP_SNDRCV;
 830         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 831         sinfo = CMSG_DATA(cmsg);
 832         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 833         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
 834         outmessage.msg_controllen = cmsg->cmsg_len;
 835
 836         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
 837         if (ret < 0) {
 838                 log_print("Send first packet to node %d failed: %d",
 839                           con->nodeid, ret);
 840
 841                 /* Try again later */
 842                 clear_bit(CF_CONNECT_PENDING, &con->flags);
 843                 clear_bit(CF_INIT_PENDING, &con->flags);
 844         }
 845         else {
 846                 spin_lock(&con->writequeue_lock);
 847                 e->offset += ret;
 848                 e->len -= ret;
 849
 850                 if (e->len == 0 && e->users == 0) {
 851                         list_del(&e->list);
 852                         kunmap(e->page);
 853                         free_entry(e);
 854                 }
 855                 spin_unlock(&con->writequeue_lock);
 856         }
 857 }
 858
 859 /* Connect a new socket to its peer */
 860 static void tcp_connect_to_sock(struct connection *con)
 861 {
 862         int result = -EHOSTUNREACH;
 863         struct sockaddr_storage saddr;
 864         int addr_len;
 865         struct socket *sock;
 866
 867         if (con->nodeid == 0) {
 868                 log_print("attempt to connect sock 0 foiled");
 869                 return;
 870         }
 871
 872         mutex_lock(&con->sock_mutex);
 873         if (con->retries++ > MAX_CONNECT_RETRIES)
 874                 goto out;
 875
 876         /* Some odd races can cause double-connects, ignore them */
 877         if (con->sock) {
 878                 result = 0;
 879                 goto out;
 880         }
 881
 882         /* Create a socket to communicate with */
 883         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 884                                   IPPROTO_TCP, &sock);
 885         if (result < 0)
 886                 goto out_err;
 887
 888         memset(&saddr, 0, sizeof(saddr));
 889         if (dlm_nodeid_to_addr(con->nodeid, &saddr))
 890                 goto out_err;
 891
 892         sock->sk->sk_user_data = con;
 893         con->rx_action = receive_from_sock;
 894         con->connect_action = tcp_connect_to_sock;
 895         add_sock(sock, con);
 896
 897         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 898
 899         log_print("connecting to %d", con->nodeid);
 900         result =
 901                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 902                                    O_NONBLOCK);
 903         if (result == -EINPROGRESS)
 904                 result = 0;
 905         if (result == 0)
 906                 goto out;
 907
 908 out_err:
 909         if (con->sock) {
 910                 sock_release(con->sock);
 911                 con->sock = NULL;
 912         }
 913         /*
 914          * Some errors are fatal and this list might need adjusting. For other
 915          * errors we try again until the max number of retries is reached.
 916          */
 917         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
 918             result != -ENETDOWN && result != EINVAL
 919             && result != -EPROTONOSUPPORT) {
 920                 lowcomms_connect_sock(con);
 921                 result = 0;
 922         }
 923 out:
 924         mutex_unlock(&con->sock_mutex);
 925         return;
 926 }
 927
 928 static struct socket *tcp_create_listen_sock(struct connection *con,
 929                                              struct sockaddr_storage *saddr)
 930 {
 931         struct socket *sock = NULL;
 932         int result = 0;
 933         int one = 1;
 934         int addr_len;
 935
 936         if (dlm_local_addr[0]->ss_family == AF_INET)
 937                 addr_len = sizeof(struct sockaddr_in);
 938         else
 939                 addr_len = sizeof(struct sockaddr_in6);
 940
 941         /* Create a socket to communicate with */
 942         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 943                                   IPPROTO_TCP, &sock);
 944         if (result < 0) {
 945                 log_print("Can't create listening comms socket");
 946                 goto create_out;
 947         }
 948
 949         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
 950                                    (char *)&one, sizeof(one));
 951
 952         if (result < 0) {
 953                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
 954         }
 955         sock->sk->sk_user_data = con;
 956         con->rx_action = tcp_accept_from_sock;
 957         con->connect_action = tcp_connect_to_sock;
 958         con->sock = sock;
 959
 960         /* Bind to our port */
 961         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
 962         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
 963         if (result < 0) {
 964                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
 965                 sock_release(sock);
 966                 sock = NULL;
 967                 con->sock = NULL;
 968                 goto create_out;
 969         }
 970         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
 971                                  (char *)&one, sizeof(one));
 972         if (result < 0) {
 973                 log_print("Set keepalive failed: %d", result);
 974         }
 975
 976         result = sock->ops->listen(sock, 5);
 977         if (result < 0) {
 978                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
 979                 sock_release(sock);
 980                 sock = NULL;
 981                 goto create_out;
 982         }
 983
 984 create_out:
 985         return sock;
 986 }
 987
 988 /* Get local addresses */
 989 static void init_local(void)
 990 {
 991         struct sockaddr_storage sas, *addr;
 992         int i;
 993
 994         dlm_local_count = 0;
 995         for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
 996                 if (dlm_our_addr(&sas, i))
 997                         break;
 998
 999                 addr = kmalloc(sizeof(*addr), GFP_KERNEL);
1000                 if (!addr)
1001                         break;
1002                 memcpy(addr, &sas, sizeof(*addr));
1003                 dlm_local_addr[dlm_local_count++] = addr;
1004         }
1005 }
1006
1007 /* Bind to an IP address. SCTP allows multiple address so it can do
1008    multi-homing */
1009 static int add_sctp_bind_addr(struct connection *sctp_con,
1010                               struct sockaddr_storage *addr,
1011                               int addr_len, int num)
1012 {
1013         int result = 0;
1014
1015         if (num == 1)
1016                 result = kernel_bind(sctp_con->sock,
1017                                      (struct sockaddr *) addr,
1018                                      addr_len);
1019         else
1020                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1021                                            SCTP_SOCKOPT_BINDX_ADD,
1022                                            (char *)addr, addr_len);
1023
1024         if (result < 0)
1025                 log_print("Can't bind to port %d addr number %d",
1026                           dlm_config.ci_tcp_port, num);
1027
1028         return result;
1029 }
1030
1031 /* Initialise SCTP socket and bind to all interfaces */
1032 static int sctp_listen_for_all(void)
1033 {
1034         struct socket *sock = NULL;
1035         struct sockaddr_storage localaddr;
1036         struct sctp_event_subscribe subscribe;
1037         int result = -EINVAL, num = 1, i, addr_len;
1038         struct connection *con = nodeid2con(0, GFP_KERNEL);
1039         int bufsize = NEEDED_RMEM;
1040
1041         if (!con)
1042                 return -ENOMEM;
1043
1044         log_print("Using SCTP for communications");
1045
1046         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1047                                   IPPROTO_SCTP, &sock);
1048         if (result < 0) {
1049                 log_print("Can't create comms socket, check SCTP is loaded");
1050                 goto out;
1051         }
1052
1053         /* Listen for events */
1054         memset(&subscribe, 0, sizeof(subscribe));
1055         subscribe.sctp_data_io_event = 1;
1056         subscribe.sctp_association_event = 1;
1057         subscribe.sctp_send_failure_event = 1;
1058         subscribe.sctp_shutdown_event = 1;
1059         subscribe.sctp_partial_delivery_event = 1;
1060
1061         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1062                                  (char *)&bufsize, sizeof(bufsize));
1063         if (result)
1064                 log_print("Error increasing buffer space on socket %d", result);
1065
1066         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1067                                    (char *)&subscribe, sizeof(subscribe));
1068         if (result < 0) {
1069                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1070                           result);
1071                 goto create_delsock;
1072         }
1073
1074         /* Init con struct */
1075         sock->sk->sk_user_data = con;
1076         con->sock = sock;
1077         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1078         con->rx_action = receive_from_sock;
1079         con->connect_action = sctp_init_assoc;
1080
1081         /* Bind to all interfaces. */
1082         for (i = 0; i < dlm_local_count; i++) {
1083                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1084                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1085
1086                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1087                 if (result)
1088                         goto create_delsock;
1089                 ++num;
1090         }
1091
1092         result = sock->ops->listen(sock, 5);
1093         if (result < 0) {
1094                 log_print("Can't set socket listening");
1095                 goto create_delsock;
1096         }
1097
1098         return 0;
1099
1100 create_delsock:
1101         sock_release(sock);
1102         con->sock = NULL;
1103 out:
1104         return result;
1105 }
1106
1107 static int tcp_listen_for_all(void)
1108 {
1109         struct socket *sock = NULL;
1110         struct connection *con = nodeid2con(0, GFP_KERNEL);
1111         int result = -EINVAL;
1112
1113         if (!con)
1114                 return -ENOMEM;
1115
1116         /* We don't support multi-homed hosts */
1117         if (dlm_local_addr[1] != NULL) {
1118                 log_print("TCP protocol can't handle multi-homed hosts, "
1119                           "try SCTP");
1120                 return -EINVAL;
1121         }
1122
1123         log_print("Using TCP for communications");
1124
1125         set_bit(CF_IS_OTHERCON, &con->flags);
1126
1127         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1128         if (sock) {
1129                 add_sock(sock, con);
1130                 result = 0;
1131         }
1132         else {
1133                 result = -EADDRINUSE;
1134         }
1135
1136         return result;
1137 }
1138
1139
1140
1141 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1142                                                      gfp_t allocation)
1143 {
1144         struct writequeue_entry *entry;
1145
1146         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1147         if (!entry)
1148                 return NULL;
1149
1150         entry->page = alloc_page(allocation);
1151         if (!entry->page) {
1152                 kfree(entry);
1153                 return NULL;
1154         }
1155
1156         entry->offset = 0;
1157         entry->len = 0;
1158         entry->end = 0;
1159         entry->users = 0;
1160         entry->con = con;
1161
1162         return entry;
1163 }
1164
1165 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1166 {
1167         struct connection *con;
1168         struct writequeue_entry *e;
1169         int offset = 0;
1170         int users = 0;
1171
1172         con = nodeid2con(nodeid, allocation);
1173         if (!con)
1174                 return NULL;
1175
1176         spin_lock(&con->writequeue_lock);
1177         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1178         if ((&e->list == &con->writequeue) ||
1179             (PAGE_CACHE_SIZE - e->end < len)) {
1180                 e = NULL;
1181         } else {
1182                 offset = e->end;
1183                 e->end += len;
1184                 users = e->users++;
1185         }
1186         spin_unlock(&con->writequeue_lock);
1187
1188         if (e) {
1189         got_one:
1190                 if (users == 0)
1191                         kmap(e->page);
1192                 *ppc = page_address(e->page) + offset;
1193                 return e;
1194         }
1195
1196         e = new_writequeue_entry(con, allocation);
1197         if (e) {
1198                 spin_lock(&con->writequeue_lock);
1199                 offset = e->end;
1200                 e->end += len;
1201                 users = e->users++;
1202                 list_add_tail(&e->list, &con->writequeue);
1203                 spin_unlock(&con->writequeue_lock);
1204                 goto got_one;
1205         }
1206         return NULL;
1207 }
1208
1209 void dlm_lowcomms_commit_buffer(void *mh)
1210 {
1211         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1212         struct connection *con = e->con;
1213         int users;
1214
1215         spin_lock(&con->writequeue_lock);
1216         users = --e->users;
1217         if (users)
1218                 goto out;
1219         e->len = e->end - e->offset;
1220         kunmap(e->page);
1221         spin_unlock(&con->writequeue_lock);
1222
1223         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1224                 queue_work(send_workqueue, &con->swork);
1225         }
1226         return;
1227
1228 out:
1229         spin_unlock(&con->writequeue_lock);
1230         return;
1231 }
1232
1233 /* Send a message */
1234 static void send_to_sock(struct connection *con)
1235 {
1236         int ret = 0;
1237         ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
1238         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1239         struct writequeue_entry *e;
1240         int len, offset;
1241
1242         mutex_lock(&con->sock_mutex);
1243         if (con->sock == NULL)
1244                 goto out_connect;
1245
1246         sendpage = con->sock->ops->sendpage;
1247
1248         spin_lock(&con->writequeue_lock);
1249         for (;;) {
1250                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1251                                list);
1252                 if ((struct list_head *) e == &con->writequeue)
1253                         break;
1254
1255                 len = e->len;
1256                 offset = e->offset;
1257                 BUG_ON(len == 0 && e->users == 0);
1258                 spin_unlock(&con->writequeue_lock);
1259                 kmap(e->page);
1260
1261                 ret = 0;
1262                 if (len) {
1263                         ret = sendpage(con->sock, e->page, offset, len,
1264                                        msg_flags);
1265                         if (ret == -EAGAIN || ret == 0)
1266                                 goto out;
1267                         if (ret <= 0)
1268                                 goto send_error;
1269                 } else {
1270                         /* Don't starve people filling buffers */
1271                         cond_resched();
1272                 }
1273
1274                 spin_lock(&con->writequeue_lock);
1275                 e->offset += ret;
1276                 e->len -= ret;
1277
1278                 if (e->len == 0 && e->users == 0) {
1279                         list_del(&e->list);
1280                         kunmap(e->page);
1281                         free_entry(e);
1282                         continue;
1283                 }
1284         }
1285         spin_unlock(&con->writequeue_lock);
1286 out:
1287         mutex_unlock(&con->sock_mutex);
1288         return;
1289
1290 send_error:
1291         mutex_unlock(&con->sock_mutex);
1292         close_connection(con, false);
1293         lowcomms_connect_sock(con);
1294         return;
1295
1296 out_connect:
1297         mutex_unlock(&con->sock_mutex);
1298         if (!test_bit(CF_INIT_PENDING, &con->flags))
1299                 lowcomms_connect_sock(con);
1300         return;
1301 }
1302
1303 static void clean_one_writequeue(struct connection *con)
1304 {
1305         struct list_head *list;
1306         struct list_head *temp;
1307
1308         spin_lock(&con->writequeue_lock);
1309         list_for_each_safe(list, temp, &con->writequeue) {
1310                 struct writequeue_entry *e =
1311                         list_entry(list, struct writequeue_entry, list);
1312                 list_del(&e->list);
1313                 free_entry(e);
1314         }
1315         spin_unlock(&con->writequeue_lock);
1316 }
1317
1318 /* Called from recovery when it knows that a node has
1319    left the cluster */
1320 int dlm_lowcomms_close(int nodeid)
1321 {
1322         struct connection *con;
1323
1324         log_print("closing connection to node %d", nodeid);
1325         con = nodeid2con(nodeid, 0);
1326         if (con) {
1327                 clean_one_writequeue(con);
1328                 close_connection(con, true);
1329         }
1330         return 0;
1331 }
1332
1333 /* Receive workqueue function */
1334 static void process_recv_sockets(struct work_struct *work)
1335 {
1336         struct connection *con = container_of(work, struct connection, rwork);
1337         int err;
1338
1339         clear_bit(CF_READ_PENDING, &con->flags);
1340         do {
1341                 err = con->rx_action(con);
1342         } while (!err);
1343 }
1344
1345 /* Send workqueue function */
1346 static void process_send_sockets(struct work_struct *work)
1347 {
1348         struct connection *con = container_of(work, struct connection, swork);
1349
1350         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1351                 con->connect_action(con);
1352         }
1353         clear_bit(CF_WRITE_PENDING, &con->flags);
1354         send_to_sock(con);
1355 }
1356
1357
1358 /* Discard all entries on the write queues */
1359 static void clean_writequeues(void)
1360 {
1361         int nodeid;
1362
1363         for (nodeid = 1; nodeid <= max_nodeid; nodeid++) {
1364                 struct connection *con = __nodeid2con(nodeid, 0);
1365
1366                 if (con)
1367                         clean_one_writequeue(con);
1368         }
1369 }
1370
1371 static void work_stop(void)
1372 {
1373         destroy_workqueue(recv_workqueue);
1374         destroy_workqueue(send_workqueue);
1375 }
1376
1377 static int work_start(void)
1378 {
1379         int error;
1380         recv_workqueue = create_workqueue("dlm_recv");
1381         error = IS_ERR(recv_workqueue);
1382         if (error) {
1383                 log_print("can't start dlm_recv %d", error);
1384                 return error;
1385         }
1386
1387         send_workqueue = create_singlethread_workqueue("dlm_send");
1388         error = IS_ERR(send_workqueue);
1389         if (error) {
1390                 log_print("can't start dlm_send %d", error);
1391                 destroy_workqueue(recv_workqueue);
1392                 return error;
1393         }
1394
1395         return 0;
1396 }
1397
1398 void dlm_lowcomms_stop(void)
1399 {
1400         int i;
1401         struct connection *con;
1402
1403         /* Set all the flags to prevent any
1404            socket activity.
1405         */
1406         down(&connections_lock);
1407         for (i = 0; i <= max_nodeid; i++) {
1408                 con = __nodeid2con(i, 0);
1409                 if (con) {
1410                         con->flags |= 0xFF;
1411                         if (con->sock)
1412                                 con->sock->sk->sk_user_data = NULL;
1413                 }
1414         }
1415         up(&connections_lock);
1416
1417         work_stop();
1418
1419         down(&connections_lock);
1420         clean_writequeues();
1421
1422         for (i = 0; i <= max_nodeid; i++) {
1423                 con = __nodeid2con(i, 0);
1424                 if (con) {
1425                         close_connection(con, true);
1426                         if (con->othercon)
1427                                 kmem_cache_free(con_cache, con->othercon);
1428                         kmem_cache_free(con_cache, con);
1429                 }
1430         }
1431         max_nodeid = 0;
1432         up(&connections_lock);
1433         kmem_cache_destroy(con_cache);
1434         idr_init(&connections_idr);
1435 }
1436
1437 int dlm_lowcomms_start(void)
1438 {
1439         int error = -EINVAL;
1440         struct connection *con;
1441
1442         init_local();
1443         if (!dlm_local_count) {
1444                 error = -ENOTCONN;
1445                 log_print("no local IP address has been set");
1446                 goto out;
1447         }
1448
1449         error = -ENOMEM;
1450         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1451                                       __alignof__(struct connection), 0,
1452                                       NULL, NULL);
1453         if (!con_cache)
1454                 goto out;
1455
1456         /* Set some sysctl minima */
1457         if (sysctl_rmem_max < NEEDED_RMEM)
1458                 sysctl_rmem_max = NEEDED_RMEM;
1459
1460         /* Start listening */
1461         if (dlm_config.ci_protocol == 0)
1462                 error = tcp_listen_for_all();
1463         else
1464                 error = sctp_listen_for_all();
1465         if (error)
1466                 goto fail_unlisten;
1467
1468         error = work_start();
1469         if (error)
1470                 goto fail_unlisten;
1471
1472         return 0;
1473
1474 fail_unlisten:
1475         con = nodeid2con(0,0);
1476         if (con) {
1477                 close_connection(con, false);
1478                 kmem_cache_free(con_cache, con);
1479         }
1480         kmem_cache_destroy(con_cache);
1481
1482 out:
1483         return error;
1484 }