fs/dlm/lowcomms.c

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2009 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 its
  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 either 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 should be 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/file.h>
  52 #include <linux/mutex.h>
  53 #include <linux/sctp.h>
  54 #include <net/sctp/user.h>
  55 #include <net/ipv6.h>
  56
  57 #include "dlm_internal.h"
  58 #include "lowcomms.h"
  59 #include "midcomms.h"
  60 #include "config.h"
  61
  62 #define NEEDED_RMEM (4*1024*1024)
  63 #define CONN_HASH_SIZE 32
  64
  65 struct cbuf {
  66         unsigned int base;
  67         unsigned int len;
  68         unsigned int mask;
  69 };
  70
  71 static void cbuf_add(struct cbuf *cb, int n)
  72 {
  73         cb->len += n;
  74 }
  75
  76 static int cbuf_data(struct cbuf *cb)
  77 {
  78         return ((cb->base + cb->len) & cb->mask);
  79 }
  80
  81 static void cbuf_init(struct cbuf *cb, int size)
  82 {
  83         cb->base = cb->len = 0;
  84         cb->mask = size-1;
  85 }
  86
  87 static void cbuf_eat(struct cbuf *cb, int n)
  88 {
  89         cb->len  -= n;
  90         cb->base += n;
  91         cb->base &= cb->mask;
  92 }
  93
  94 static bool cbuf_empty(struct cbuf *cb)
  95 {
  96         return cb->len == 0;
  97 }
  98
  99 struct connection {
 100         struct socket *sock;    /* NULL if not connected */
 101         uint32_t nodeid;        /* So we know who we are in the list */
 102         struct mutex sock_mutex;
 103         unsigned long flags;
 104 #define CF_READ_PENDING 1
 105 #define CF_WRITE_PENDING 2
 106 #define CF_CONNECT_PENDING 3
 107 #define CF_INIT_PENDING 4
 108 #define CF_IS_OTHERCON 5
 109 #define CF_CLOSE 6
 110         struct list_head writequeue;  /* List of outgoing writequeue_entries */
 111         spinlock_t writequeue_lock;
 112         int (*rx_action) (struct connection *); /* What to do when active */
 113         void (*connect_action) (struct connection *);   /* What to do to connect */
 114         struct page *rx_page;
 115         struct cbuf cb;
 116         int retries;
 117 #define MAX_CONNECT_RETRIES 3
 118         int sctp_assoc;
 119         struct hlist_node list;
 120         struct connection *othercon;
 121         struct work_struct rwork; /* Receive workqueue */
 122         struct work_struct swork; /* Send workqueue */
 123 };
 124 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
 125
 126 /* An entry waiting to be sent */
 127 struct writequeue_entry {
 128         struct list_head list;
 129         struct page *page;
 130         int offset;
 131         int len;
 132         int end;
 133         int users;
 134         struct connection *con;
 135 };
 136
 137 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 138 static int dlm_local_count;
 139
 140 /* Work queues */
 141 static struct workqueue_struct *recv_workqueue;
 142 static struct workqueue_struct *send_workqueue;
 143
 144 static struct hlist_head connection_hash[CONN_HASH_SIZE];
 145 static DEFINE_MUTEX(connections_lock);
 146 static struct kmem_cache *con_cache;
 147
 148 static void process_recv_sockets(struct work_struct *work);
 149 static void process_send_sockets(struct work_struct *work);
 150
 151
 152 /* This is deliberately very simple because most clusters have simple
 153    sequential nodeids, so we should be able to go straight to a connection
 154    struct in the array */
 155 static inline int nodeid_hash(int nodeid)
 156 {
 157         return nodeid & (CONN_HASH_SIZE-1);
 158 }
 159
 160 static struct connection *__find_con(int nodeid)
 161 {
 162         int r;
 163         struct hlist_node *h;
 164         struct connection *con;
 165
 166         r = nodeid_hash(nodeid);
 167
 168         hlist_for_each_entry(con, h, &connection_hash[r], list) {
 169                 if (con->nodeid == nodeid)
 170                         return con;
 171         }
 172         return NULL;
 173 }
 174
 175 /*
 176  * If 'allocation' is zero then we don't attempt to create a new
 177  * connection structure for this node.
 178  */
 179 static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
 180 {
 181         struct connection *con = NULL;
 182         int r;
 183
 184         con = __find_con(nodeid);
 185         if (con || !alloc)
 186                 return con;
 187
 188         con = kmem_cache_zalloc(con_cache, alloc);
 189         if (!con)
 190                 return NULL;
 191
 192         r = nodeid_hash(nodeid);
 193         hlist_add_head(&con->list, &connection_hash[r]);
 194
 195         con->nodeid = nodeid;
 196         mutex_init(&con->sock_mutex);
 197         INIT_LIST_HEAD(&con->writequeue);
 198         spin_lock_init(&con->writequeue_lock);
 199         INIT_WORK(&con->swork, process_send_sockets);
 200         INIT_WORK(&con->rwork, process_recv_sockets);
 201
 202         /* Setup action pointers for child sockets */
 203         if (con->nodeid) {
 204                 struct connection *zerocon = __find_con(0);
 205
 206                 con->connect_action = zerocon->connect_action;
 207                 if (!con->rx_action)
 208                         con->rx_action = zerocon->rx_action;
 209         }
 210
 211         return con;
 212 }
 213
 214 /* Loop round all connections */
 215 static void foreach_conn(void (*conn_func)(struct connection *c))
 216 {
 217         int i;
 218         struct hlist_node *h, *n;
 219         struct connection *con;
 220
 221         for (i = 0; i < CONN_HASH_SIZE; i++) {
 222                 hlist_for_each_entry_safe(con, h, n, &connection_hash[i], list){
 223                         conn_func(con);
 224                 }
 225         }
 226 }
 227
 228 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
 229 {
 230         struct connection *con;
 231
 232         mutex_lock(&connections_lock);
 233         con = __nodeid2con(nodeid, allocation);
 234         mutex_unlock(&connections_lock);
 235
 236         return con;
 237 }
 238
 239 /* This is a bit drastic, but only called when things go wrong */
 240 static struct connection *assoc2con(int assoc_id)
 241 {
 242         int i;
 243         struct hlist_node *h;
 244         struct connection *con;
 245
 246         mutex_lock(&connections_lock);
 247
 248         for (i = 0 ; i < CONN_HASH_SIZE; i++) {
 249                 hlist_for_each_entry(con, h, &connection_hash[i], list) {
 250                         if (con && con->sctp_assoc == assoc_id) {
 251                                 mutex_unlock(&connections_lock);
 252                                 return con;
 253                         }
 254                 }
 255         }
 256         mutex_unlock(&connections_lock);
 257         return NULL;
 258 }
 259
 260 static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
 261 {
 262         struct sockaddr_storage addr;
 263         int error;
 264
 265         if (!dlm_local_count)
 266                 return -1;
 267
 268         error = dlm_nodeid_to_addr(nodeid, &addr);
 269         if (error)
 270                 return error;
 271
 272         if (dlm_local_addr[0]->ss_family == AF_INET) {
 273                 struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
 274                 struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
 275                 ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
 276         } else {
 277                 struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
 278                 struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
 279                 ipv6_addr_copy(&ret6->sin6_addr, &in6->sin6_addr);
 280         }
 281
 282         return 0;
 283 }
 284
 285 /* Data available on socket or listen socket received a connect */
 286 static void lowcomms_data_ready(struct sock *sk, int count_unused)
 287 {
 288         struct connection *con = sock2con(sk);
 289         if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
 290                 queue_work(recv_workqueue, &con->rwork);
 291 }
 292
 293 static void lowcomms_write_space(struct sock *sk)
 294 {
 295         struct connection *con = sock2con(sk);
 296
 297         if (con && !test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 298                 queue_work(send_workqueue, &con->swork);
 299 }
 300
 301 static inline void lowcomms_connect_sock(struct connection *con)
 302 {
 303         if (test_bit(CF_CLOSE, &con->flags))
 304                 return;
 305         if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
 306                 queue_work(send_workqueue, &con->swork);
 307 }
 308
 309 static void lowcomms_state_change(struct sock *sk)
 310 {
 311         if (sk->sk_state == TCP_ESTABLISHED)
 312                 lowcomms_write_space(sk);
 313 }
 314
 315 int dlm_lowcomms_connect_node(int nodeid)
 316 {
 317         struct connection *con;
 318
 319         if (nodeid == dlm_our_nodeid())
 320                 return 0;
 321
 322         con = nodeid2con(nodeid, GFP_NOFS);
 323         if (!con)
 324                 return -ENOMEM;
 325         lowcomms_connect_sock(con);
 326         return 0;
 327 }
 328
 329 /* Make a socket active */
 330 static int add_sock(struct socket *sock, struct connection *con)
 331 {
 332         con->sock = sock;
 333
 334         /* Install a data_ready callback */
 335         con->sock->sk->sk_data_ready = lowcomms_data_ready;
 336         con->sock->sk->sk_write_space = lowcomms_write_space;
 337         con->sock->sk->sk_state_change = lowcomms_state_change;
 338         con->sock->sk->sk_user_data = con;
 339         con->sock->sk->sk_allocation = GFP_NOFS;
 340         return 0;
 341 }
 342
 343 /* Add the port number to an IPv6 or 4 sockaddr and return the address
 344    length */
 345 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 346                           int *addr_len)
 347 {
 348         saddr->ss_family =  dlm_local_addr[0]->ss_family;
 349         if (saddr->ss_family == AF_INET) {
 350                 struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
 351                 in4_addr->sin_port = cpu_to_be16(port);
 352                 *addr_len = sizeof(struct sockaddr_in);
 353                 memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
 354         } else {
 355                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
 356                 in6_addr->sin6_port = cpu_to_be16(port);
 357                 *addr_len = sizeof(struct sockaddr_in6);
 358         }
 359         memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
 360 }
 361
 362 /* Close a remote connection and tidy up */
 363 static void close_connection(struct connection *con, bool and_other)
 364 {
 365         mutex_lock(&con->sock_mutex);
 366
 367         if (con->sock) {
 368                 sock_release(con->sock);
 369                 con->sock = NULL;
 370         }
 371         if (con->othercon && and_other) {
 372                 /* Will only re-enter once. */
 373                 close_connection(con->othercon, false);
 374         }
 375         if (con->rx_page) {
 376                 __free_page(con->rx_page);
 377                 con->rx_page = NULL;
 378         }
 379
 380         con->retries = 0;
 381         mutex_unlock(&con->sock_mutex);
 382 }
 383
 384 /* We only send shutdown messages to nodes that are not part of the cluster */
 385 static void sctp_send_shutdown(sctp_assoc_t associd)
 386 {
 387         static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 388         struct msghdr outmessage;
 389         struct cmsghdr *cmsg;
 390         struct sctp_sndrcvinfo *sinfo;
 391         int ret;
 392         struct connection *con;
 393
 394         con = nodeid2con(0,0);
 395         BUG_ON(con == NULL);
 396
 397         outmessage.msg_name = NULL;
 398         outmessage.msg_namelen = 0;
 399         outmessage.msg_control = outcmsg;
 400         outmessage.msg_controllen = sizeof(outcmsg);
 401         outmessage.msg_flags = MSG_EOR;
 402
 403         cmsg = CMSG_FIRSTHDR(&outmessage);
 404         cmsg->cmsg_level = IPPROTO_SCTP;
 405         cmsg->cmsg_type = SCTP_SNDRCV;
 406         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 407         outmessage.msg_controllen = cmsg->cmsg_len;
 408         sinfo = CMSG_DATA(cmsg);
 409         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 410
 411         sinfo->sinfo_flags |= MSG_EOF;
 412         sinfo->sinfo_assoc_id = associd;
 413
 414         ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);
 415
 416         if (ret != 0)
 417                 log_print("send EOF to node failed: %d", ret);
 418 }
 419
 420 static void sctp_init_failed_foreach(struct connection *con)
 421 {
 422         con->sctp_assoc = 0;
 423         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
 424                 if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 425                         queue_work(send_workqueue, &con->swork);
 426         }
 427 }
 428
 429 /* INIT failed but we don't know which node...
 430    restart INIT on all pending nodes */
 431 static void sctp_init_failed(void)
 432 {
 433         mutex_lock(&connections_lock);
 434
 435         foreach_conn(sctp_init_failed_foreach);
 436
 437         mutex_unlock(&connections_lock);
 438 }
 439
 440 /* Something happened to an association */
 441 static void process_sctp_notification(struct connection *con,
 442                                       struct msghdr *msg, char *buf)
 443 {
 444         union sctp_notification *sn = (union sctp_notification *)buf;
 445
 446         if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
 447                 switch (sn->sn_assoc_change.sac_state) {
 448
 449                 case SCTP_COMM_UP:
 450                 case SCTP_RESTART:
 451                 {
 452                         /* Check that the new node is in the lockspace */
 453                         struct sctp_prim prim;
 454                         int nodeid;
 455                         int prim_len, ret;
 456                         int addr_len;
 457                         struct connection *new_con;
 458                         struct file *file;
 459                         sctp_peeloff_arg_t parg;
 460                         int parglen = sizeof(parg);
 461
 462                         /*
 463                          * We get this before any data for an association.
 464                          * We verify that the node is in the cluster and
 465                          * then peel off a socket for it.
 466                          */
 467                         if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
 468                                 log_print("COMM_UP for invalid assoc ID %d",
 469                                          (int)sn->sn_assoc_change.sac_assoc_id);
 470                                 sctp_init_failed();
 471                                 return;
 472                         }
 473                         memset(&prim, 0, sizeof(struct sctp_prim));
 474                         prim_len = sizeof(struct sctp_prim);
 475                         prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
 476
 477                         ret = kernel_getsockopt(con->sock,
 478                                                 IPPROTO_SCTP,
 479                                                 SCTP_PRIMARY_ADDR,
 480                                                 (char*)&prim,
 481                                                 &prim_len);
 482                         if (ret < 0) {
 483                                 log_print("getsockopt/sctp_primary_addr on "
 484                                           "new assoc %d failed : %d",
 485                                           (int)sn->sn_assoc_change.sac_assoc_id,
 486                                           ret);
 487
 488                                 /* Retry INIT later */
 489                                 new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 490                                 if (new_con)
 491                                         clear_bit(CF_CONNECT_PENDING, &con->flags);
 492                                 return;
 493                         }
 494                         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
 495                         if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
 496                                 int i;
 497                                 unsigned char *b=(unsigned char *)&prim.ssp_addr;
 498                                 log_print("reject connect from unknown addr");
 499                                 for (i=0; i<sizeof(struct sockaddr_storage);i++)
 500                                         printk("%02x ", b[i]);
 501                                 printk("\n");
 502                                 sctp_send_shutdown(prim.ssp_assoc_id);
 503                                 return;
 504                         }
 505
 506                         new_con = nodeid2con(nodeid, GFP_NOFS);
 507                         if (!new_con)
 508                                 return;
 509
 510                         /* Peel off a new sock */
 511                         parg.associd = sn->sn_assoc_change.sac_assoc_id;
 512                         ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
 513                                                 SCTP_SOCKOPT_PEELOFF,
 514                                                 (void *)&parg, &parglen);
 515                         if (ret) {
 516                                 log_print("Can't peel off a socket for "
 517                                           "connection %d to node %d: err=%d\n",
 518                                           parg.associd, nodeid, ret);
 519                         }
 520                         file = fget(parg.sd);
 521                         new_con->sock = SOCKET_I(file->f_dentry->d_inode);
 522                         add_sock(new_con->sock, new_con);
 523                         fput(file);
 524                         put_unused_fd(parg.sd);
 525
 526                         log_print("got new/restarted association %d nodeid %d",
 527                                  (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
 528
 529                         /* Send any pending writes */
 530                         clear_bit(CF_CONNECT_PENDING, &new_con->flags);
 531                         clear_bit(CF_INIT_PENDING, &con->flags);
 532                         if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
 533                                 queue_work(send_workqueue, &new_con->swork);
 534                         }
 535                         if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))
 536                                 queue_work(recv_workqueue, &new_con->rwork);
 537                 }
 538                 break;
 539
 540                 case SCTP_COMM_LOST:
 541                 case SCTP_SHUTDOWN_COMP:
 542                 {
 543                         con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 544                         if (con) {
 545                                 con->sctp_assoc = 0;
 546                         }
 547                 }
 548                 break;
 549
 550                 /* We don't know which INIT failed, so clear the PENDING flags
 551                  * on them all.  if assoc_id is zero then it will then try
 552                  * again */
 553
 554                 case SCTP_CANT_STR_ASSOC:
 555                 {
 556                         log_print("Can't start SCTP association - retrying");
 557                         sctp_init_failed();
 558                 }
 559                 break;
 560
 561                 default:
 562                         log_print("unexpected SCTP assoc change id=%d state=%d",
 563                                   (int)sn->sn_assoc_change.sac_assoc_id,
 564                                   sn->sn_assoc_change.sac_state);
 565                 }
 566         }
 567 }
 568
 569 /* Data received from remote end */
 570 static int receive_from_sock(struct connection *con)
 571 {
 572         int ret = 0;
 573         struct msghdr msg = {};
 574         struct kvec iov[2];
 575         unsigned len;
 576         int r;
 577         int call_again_soon = 0;
 578         int nvec;
 579         char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 580
 581         mutex_lock(&con->sock_mutex);
 582
 583         if (con->sock == NULL) {
 584                 ret = -EAGAIN;
 585                 goto out_close;
 586         }
 587
 588         if (con->rx_page == NULL) {
 589                 /*
 590                  * This doesn't need to be atomic, but I think it should
 591                  * improve performance if it is.
 592                  */
 593                 con->rx_page = alloc_page(GFP_ATOMIC);
 594                 if (con->rx_page == NULL)
 595                         goto out_resched;
 596                 cbuf_init(&con->cb, PAGE_CACHE_SIZE);
 597         }
 598
 599         /* Only SCTP needs these really */
 600         memset(&incmsg, 0, sizeof(incmsg));
 601         msg.msg_control = incmsg;
 602         msg.msg_controllen = sizeof(incmsg);
 603
 604         /*
 605          * iov[0] is the bit of the circular buffer between the current end
 606          * point (cb.base + cb.len) and the end of the buffer.
 607          */
 608         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
 609         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
 610         iov[1].iov_len = 0;
 611         nvec = 1;
 612
 613         /*
 614          * iov[1] is the bit of the circular buffer between the start of the
 615          * buffer and the start of the currently used section (cb.base)
 616          */
 617         if (cbuf_data(&con->cb) >= con->cb.base) {
 618                 iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
 619                 iov[1].iov_len = con->cb.base;
 620                 iov[1].iov_base = page_address(con->rx_page);
 621                 nvec = 2;
 622         }
 623         len = iov[0].iov_len + iov[1].iov_len;
 624
 625         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
 626                                MSG_DONTWAIT | MSG_NOSIGNAL);
 627         if (ret <= 0)
 628                 goto out_close;
 629
 630         /* Process SCTP notifications */
 631         if (msg.msg_flags & MSG_NOTIFICATION) {
 632                 msg.msg_control = incmsg;
 633                 msg.msg_controllen = sizeof(incmsg);
 634
 635                 process_sctp_notification(con, &msg,
 636                                 page_address(con->rx_page) + con->cb.base);
 637                 mutex_unlock(&con->sock_mutex);
 638                 return 0;
 639         }
 640         BUG_ON(con->nodeid == 0);
 641
 642         if (ret == len)
 643                 call_again_soon = 1;
 644         cbuf_add(&con->cb, ret);
 645         ret = dlm_process_incoming_buffer(con->nodeid,
 646                                           page_address(con->rx_page),
 647                                           con->cb.base, con->cb.len,
 648                                           PAGE_CACHE_SIZE);
 649         if (ret == -EBADMSG) {
 650                 log_print("lowcomms: addr=%p, base=%u, len=%u, "
 651                           "iov_len=%u, iov_base[0]=%p, read=%d",
 652                           page_address(con->rx_page), con->cb.base, con->cb.len,
 653                           len, iov[0].iov_base, r);
 654         }
 655         if (ret < 0)
 656                 goto out_close;
 657         cbuf_eat(&con->cb, ret);
 658
 659         if (cbuf_empty(&con->cb) && !call_again_soon) {
 660                 __free_page(con->rx_page);
 661                 con->rx_page = NULL;
 662         }
 663
 664         if (call_again_soon)
 665                 goto out_resched;
 666         mutex_unlock(&con->sock_mutex);
 667         return 0;
 668
 669 out_resched:
 670         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
 671                 queue_work(recv_workqueue, &con->rwork);
 672         mutex_unlock(&con->sock_mutex);
 673         return -EAGAIN;
 674
 675 out_close:
 676         mutex_unlock(&con->sock_mutex);
 677         if (ret != -EAGAIN) {
 678                 close_connection(con, false);
 679                 /* Reconnect when there is something to send */
 680         }
 681         /* Don't return success if we really got EOF */
 682         if (ret == 0)
 683                 ret = -EAGAIN;
 684
 685         return ret;
 686 }
 687
 688 /* Listening socket is busy, accept a connection */
 689 static int tcp_accept_from_sock(struct connection *con)
 690 {
 691         int result;
 692         struct sockaddr_storage peeraddr;
 693         struct socket *newsock;
 694         int len;
 695         int nodeid;
 696         struct connection *newcon;
 697         struct connection *addcon;
 698
 699         memset(&peeraddr, 0, sizeof(peeraddr));
 700         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 701                                   IPPROTO_TCP, &newsock);
 702         if (result < 0)
 703                 return -ENOMEM;
 704
 705         mutex_lock_nested(&con->sock_mutex, 0);
 706
 707         result = -ENOTCONN;
 708         if (con->sock == NULL)
 709                 goto accept_err;
 710
 711         newsock->type = con->sock->type;
 712         newsock->ops = con->sock->ops;
 713
 714         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
 715         if (result < 0)
 716                 goto accept_err;
 717
 718         /* Get the connected socket's peer */
 719         memset(&peeraddr, 0, sizeof(peeraddr));
 720         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
 721                                   &len, 2)) {
 722                 result = -ECONNABORTED;
 723                 goto accept_err;
 724         }
 725
 726         /* Get the new node's NODEID */
 727         make_sockaddr(&peeraddr, 0, &len);
 728         if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
 729                 log_print("connect from non cluster node");
 730                 sock_release(newsock);
 731                 mutex_unlock(&con->sock_mutex);
 732                 return -1;
 733         }
 734
 735         log_print("got connection from %d", nodeid);
 736
 737         /*  Check to see if we already have a connection to this node. This
 738          *  could happen if the two nodes initiate a connection at roughly
 739          *  the same time and the connections cross on the wire.
 740          *  In this case we store the incoming one in "othercon"
 741          */
 742         newcon = nodeid2con(nodeid, GFP_NOFS);
 743         if (!newcon) {
 744                 result = -ENOMEM;
 745                 goto accept_err;
 746         }
 747         mutex_lock_nested(&newcon->sock_mutex, 1);
 748         if (newcon->sock) {
 749                 struct connection *othercon = newcon->othercon;
 750
 751                 if (!othercon) {
 752                         othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
 753                         if (!othercon) {
 754                                 log_print("failed to allocate incoming socket");
 755                                 mutex_unlock(&newcon->sock_mutex);
 756                                 result = -ENOMEM;
 757                                 goto accept_err;
 758                         }
 759                         othercon->nodeid = nodeid;
 760                         othercon->rx_action = receive_from_sock;
 761                         mutex_init(&othercon->sock_mutex);
 762                         INIT_WORK(&othercon->swork, process_send_sockets);
 763                         INIT_WORK(&othercon->rwork, process_recv_sockets);
 764                         set_bit(CF_IS_OTHERCON, &othercon->flags);
 765                 }
 766                 if (!othercon->sock) {
 767                         newcon->othercon = othercon;
 768                         othercon->sock = newsock;
 769                         newsock->sk->sk_user_data = othercon;
 770                         add_sock(newsock, othercon);
 771                         addcon = othercon;
 772                 }
 773                 else {
 774                         printk("Extra connection from node %d attempted\n", nodeid);
 775                         result = -EAGAIN;
 776                         mutex_unlock(&newcon->sock_mutex);
 777                         goto accept_err;
 778                 }
 779         }
 780         else {
 781                 newsock->sk->sk_user_data = newcon;
 782                 newcon->rx_action = receive_from_sock;
 783                 add_sock(newsock, newcon);
 784                 addcon = newcon;
 785         }
 786
 787         mutex_unlock(&newcon->sock_mutex);
 788
 789         /*
 790          * Add it to the active queue in case we got data
 791          * beween processing the accept adding the socket
 792          * to the read_sockets list
 793          */
 794         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
 795                 queue_work(recv_workqueue, &addcon->rwork);
 796         mutex_unlock(&con->sock_mutex);
 797
 798         return 0;
 799
 800 accept_err:
 801         mutex_unlock(&con->sock_mutex);
 802         sock_release(newsock);
 803
 804         if (result != -EAGAIN)
 805                 log_print("error accepting connection from node: %d", result);
 806         return result;
 807 }
 808
 809 static void free_entry(struct writequeue_entry *e)
 810 {
 811         __free_page(e->page);
 812         kfree(e);
 813 }
 814
 815 /* Initiate an SCTP association.
 816    This is a special case of send_to_sock() in that we don't yet have a
 817    peeled-off socket for this association, so we use the listening socket
 818    and add the primary IP address of the remote node.
 819  */
 820 static void sctp_init_assoc(struct connection *con)
 821 {
 822         struct sockaddr_storage rem_addr;
 823         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 824         struct msghdr outmessage;
 825         struct cmsghdr *cmsg;
 826         struct sctp_sndrcvinfo *sinfo;
 827         struct connection *base_con;
 828         struct writequeue_entry *e;
 829         int len, offset;
 830         int ret;
 831         int addrlen;
 832         struct kvec iov[1];
 833
 834         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
 835                 return;
 836
 837         if (con->retries++ > MAX_CONNECT_RETRIES)
 838                 return;
 839
 840         log_print("Initiating association with node %d", con->nodeid);
 841
 842         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
 843                 log_print("no address for nodeid %d", con->nodeid);
 844                 return;
 845         }
 846         base_con = nodeid2con(0, 0);
 847         BUG_ON(base_con == NULL);
 848
 849         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
 850
 851         outmessage.msg_name = &rem_addr;
 852         outmessage.msg_namelen = addrlen;
 853         outmessage.msg_control = outcmsg;
 854         outmessage.msg_controllen = sizeof(outcmsg);
 855         outmessage.msg_flags = MSG_EOR;
 856
 857         spin_lock(&con->writequeue_lock);
 858         e = list_entry(con->writequeue.next, struct writequeue_entry,
 859                        list);
 860
 861         BUG_ON((struct list_head *) e == &con->writequeue);
 862
 863         len = e->len;
 864         offset = e->offset;
 865         spin_unlock(&con->writequeue_lock);
 866
 867         /* Send the first block off the write queue */
 868         iov[0].iov_base = page_address(e->page)+offset;
 869         iov[0].iov_len = len;
 870
 871         cmsg = CMSG_FIRSTHDR(&outmessage);
 872         cmsg->cmsg_level = IPPROTO_SCTP;
 873         cmsg->cmsg_type = SCTP_SNDRCV;
 874         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 875         sinfo = CMSG_DATA(cmsg);
 876         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 877         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
 878         outmessage.msg_controllen = cmsg->cmsg_len;
 879
 880         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
 881         if (ret < 0) {
 882                 log_print("Send first packet to node %d failed: %d",
 883                           con->nodeid, ret);
 884
 885                 /* Try again later */
 886                 clear_bit(CF_CONNECT_PENDING, &con->flags);
 887                 clear_bit(CF_INIT_PENDING, &con->flags);
 888         }
 889         else {
 890                 spin_lock(&con->writequeue_lock);
 891                 e->offset += ret;
 892                 e->len -= ret;
 893
 894                 if (e->len == 0 && e->users == 0) {
 895                         list_del(&e->list);
 896                         free_entry(e);
 897                 }
 898                 spin_unlock(&con->writequeue_lock);
 899         }
 900 }
 901
 902 /* Connect a new socket to its peer */
 903 static void tcp_connect_to_sock(struct connection *con)
 904 {
 905         int result = -EHOSTUNREACH;
 906         struct sockaddr_storage saddr, src_addr;
 907         int addr_len;
 908         struct socket *sock = NULL;
 909
 910         if (con->nodeid == 0) {
 911                 log_print("attempt to connect sock 0 foiled");
 912                 return;
 913         }
 914
 915         mutex_lock(&con->sock_mutex);
 916         if (con->retries++ > MAX_CONNECT_RETRIES)
 917                 goto out;
 918
 919         /* Some odd races can cause double-connects, ignore them */
 920         if (con->sock) {
 921                 result = 0;
 922                 goto out;
 923         }
 924
 925         /* Create a socket to communicate with */
 926         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 927                                   IPPROTO_TCP, &sock);
 928         if (result < 0)
 929                 goto out_err;
 930
 931         memset(&saddr, 0, sizeof(saddr));
 932         if (dlm_nodeid_to_addr(con->nodeid, &saddr))
 933                 goto out_err;
 934
 935         sock->sk->sk_user_data = con;
 936         con->rx_action = receive_from_sock;
 937         con->connect_action = tcp_connect_to_sock;
 938         add_sock(sock, con);
 939
 940         /* Bind to our cluster-known address connecting to avoid
 941            routing problems */
 942         memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
 943         make_sockaddr(&src_addr, 0, &addr_len);
 944         result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
 945                                  addr_len);
 946         if (result < 0) {
 947                 log_print("could not bind for connect: %d", result);
 948                 /* This *may* not indicate a critical error */
 949         }
 950
 951         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 952
 953         log_print("connecting to %d", con->nodeid);
 954         result =
 955                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 956                                    O_NONBLOCK);
 957         if (result == -EINPROGRESS)
 958                 result = 0;
 959         if (result == 0)
 960                 goto out;
 961
 962 out_err:
 963         if (con->sock) {
 964                 sock_release(con->sock);
 965                 con->sock = NULL;
 966         } else if (sock) {
 967                 sock_release(sock);
 968         }
 969         /*
 970          * Some errors are fatal and this list might need adjusting. For other
 971          * errors we try again until the max number of retries is reached.
 972          */
 973         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
 974             result != -ENETDOWN && result != -EINVAL
 975             && result != -EPROTONOSUPPORT) {
 976                 lowcomms_connect_sock(con);
 977                 result = 0;
 978         }
 979 out:
 980         mutex_unlock(&con->sock_mutex);
 981         return;
 982 }
 983
 984 static struct socket *tcp_create_listen_sock(struct connection *con,
 985                                              struct sockaddr_storage *saddr)
 986 {
 987         struct socket *sock = NULL;
 988         int result = 0;
 989         int one = 1;
 990         int addr_len;
 991
 992         if (dlm_local_addr[0]->ss_family == AF_INET)
 993                 addr_len = sizeof(struct sockaddr_in);
 994         else
 995                 addr_len = sizeof(struct sockaddr_in6);
 996
 997         /* Create a socket to communicate with */
 998         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 999                                   IPPROTO_TCP, &sock);
1000         if (result < 0) {
1001                 log_print("Can't create listening comms socket");
1002                 goto create_out;
1003         }
1004
1005         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
1006                                    (char *)&one, sizeof(one));
1007
1008         if (result < 0) {
1009                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
1010         }
1011         sock->sk->sk_user_data = con;
1012         con->rx_action = tcp_accept_from_sock;
1013         con->connect_action = tcp_connect_to_sock;
1014         con->sock = sock;
1015
1016         /* Bind to our port */
1017         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
1018         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
1019         if (result < 0) {
1020                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
1021                 sock_release(sock);
1022                 sock = NULL;
1023                 con->sock = NULL;
1024                 goto create_out;
1025         }
1026         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
1027                                  (char *)&one, sizeof(one));
1028         if (result < 0) {
1029                 log_print("Set keepalive failed: %d", result);
1030         }
1031
1032         result = sock->ops->listen(sock, 5);
1033         if (result < 0) {
1034                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
1035                 sock_release(sock);
1036                 sock = NULL;
1037                 goto create_out;
1038         }
1039
1040 create_out:
1041         return sock;
1042 }
1043
1044 /* Get local addresses */
1045 static void init_local(void)
1046 {
1047         struct sockaddr_storage sas, *addr;
1048         int i;
1049
1050         dlm_local_count = 0;
1051         for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
1052                 if (dlm_our_addr(&sas, i))
1053                         break;
1054
1055                 addr = kmalloc(sizeof(*addr), GFP_KERNEL);
1056                 if (!addr)
1057                         break;
1058                 memcpy(addr, &sas, sizeof(*addr));
1059                 dlm_local_addr[dlm_local_count++] = addr;
1060         }
1061 }
1062
1063 /* Bind to an IP address. SCTP allows multiple address so it can do
1064    multi-homing */
1065 static int add_sctp_bind_addr(struct connection *sctp_con,
1066                               struct sockaddr_storage *addr,
1067                               int addr_len, int num)
1068 {
1069         int result = 0;
1070
1071         if (num == 1)
1072                 result = kernel_bind(sctp_con->sock,
1073                                      (struct sockaddr *) addr,
1074                                      addr_len);
1075         else
1076                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1077                                            SCTP_SOCKOPT_BINDX_ADD,
1078                                            (char *)addr, addr_len);
1079
1080         if (result < 0)
1081                 log_print("Can't bind to port %d addr number %d",
1082                           dlm_config.ci_tcp_port, num);
1083
1084         return result;
1085 }
1086
1087 /* Initialise SCTP socket and bind to all interfaces */
1088 static int sctp_listen_for_all(void)
1089 {
1090         struct socket *sock = NULL;
1091         struct sockaddr_storage localaddr;
1092         struct sctp_event_subscribe subscribe;
1093         int result = -EINVAL, num = 1, i, addr_len;
1094         struct connection *con = nodeid2con(0, GFP_KERNEL);
1095         int bufsize = NEEDED_RMEM;
1096
1097         if (!con)
1098                 return -ENOMEM;
1099
1100         log_print("Using SCTP for communications");
1101
1102         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1103                                   IPPROTO_SCTP, &sock);
1104         if (result < 0) {
1105                 log_print("Can't create comms socket, check SCTP is loaded");
1106                 goto out;
1107         }
1108
1109         /* Listen for events */
1110         memset(&subscribe, 0, sizeof(subscribe));
1111         subscribe.sctp_data_io_event = 1;
1112         subscribe.sctp_association_event = 1;
1113         subscribe.sctp_send_failure_event = 1;
1114         subscribe.sctp_shutdown_event = 1;
1115         subscribe.sctp_partial_delivery_event = 1;
1116
1117         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
1118                                  (char *)&bufsize, sizeof(bufsize));
1119         if (result)
1120                 log_print("Error increasing buffer space on socket %d", result);
1121
1122         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1123                                    (char *)&subscribe, sizeof(subscribe));
1124         if (result < 0) {
1125                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1126                           result);
1127                 goto create_delsock;
1128         }
1129
1130         /* Init con struct */
1131         sock->sk->sk_user_data = con;
1132         con->sock = sock;
1133         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1134         con->rx_action = receive_from_sock;
1135         con->connect_action = sctp_init_assoc;
1136
1137         /* Bind to all interfaces. */
1138         for (i = 0; i < dlm_local_count; i++) {
1139                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1140                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1141
1142                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1143                 if (result)
1144                         goto create_delsock;
1145                 ++num;
1146         }
1147
1148         result = sock->ops->listen(sock, 5);
1149         if (result < 0) {
1150                 log_print("Can't set socket listening");
1151                 goto create_delsock;
1152         }
1153
1154         return 0;
1155
1156 create_delsock:
1157         sock_release(sock);
1158         con->sock = NULL;
1159 out:
1160         return result;
1161 }
1162
1163 static int tcp_listen_for_all(void)
1164 {
1165         struct socket *sock = NULL;
1166         struct connection *con = nodeid2con(0, GFP_KERNEL);
1167         int result = -EINVAL;
1168
1169         if (!con)
1170                 return -ENOMEM;
1171
1172         /* We don't support multi-homed hosts */
1173         if (dlm_local_addr[1] != NULL) {
1174                 log_print("TCP protocol can't handle multi-homed hosts, "
1175                           "try SCTP");
1176                 return -EINVAL;
1177         }
1178
1179         log_print("Using TCP for communications");
1180
1181         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1182         if (sock) {
1183                 add_sock(sock, con);
1184                 result = 0;
1185         }
1186         else {
1187                 result = -EADDRINUSE;
1188         }
1189
1190         return result;
1191 }
1192
1193
1194
1195 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1196                                                      gfp_t allocation)
1197 {
1198         struct writequeue_entry *entry;
1199
1200         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1201         if (!entry)
1202                 return NULL;
1203
1204         entry->page = alloc_page(allocation);
1205         if (!entry->page) {
1206                 kfree(entry);
1207                 return NULL;
1208         }
1209
1210         entry->offset = 0;
1211         entry->len = 0;
1212         entry->end = 0;
1213         entry->users = 0;
1214         entry->con = con;
1215
1216         return entry;
1217 }
1218
1219 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1220 {
1221         struct connection *con;
1222         struct writequeue_entry *e;
1223         int offset = 0;
1224         int users = 0;
1225
1226         con = nodeid2con(nodeid, allocation);
1227         if (!con)
1228                 return NULL;
1229
1230         spin_lock(&con->writequeue_lock);
1231         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1232         if ((&e->list == &con->writequeue) ||
1233             (PAGE_CACHE_SIZE - e->end < len)) {
1234                 e = NULL;
1235         } else {
1236                 offset = e->end;
1237                 e->end += len;
1238                 users = e->users++;
1239         }
1240         spin_unlock(&con->writequeue_lock);
1241
1242         if (e) {
1243         got_one:
1244                 *ppc = page_address(e->page) + offset;
1245                 return e;
1246         }
1247
1248         e = new_writequeue_entry(con, allocation);
1249         if (e) {
1250                 spin_lock(&con->writequeue_lock);
1251                 offset = e->end;
1252                 e->end += len;
1253                 users = e->users++;
1254                 list_add_tail(&e->list, &con->writequeue);
1255                 spin_unlock(&con->writequeue_lock);
1256                 goto got_one;
1257         }
1258         return NULL;
1259 }
1260
1261 void dlm_lowcomms_commit_buffer(void *mh)
1262 {
1263         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1264         struct connection *con = e->con;
1265         int users;
1266
1267         spin_lock(&con->writequeue_lock);
1268         users = --e->users;
1269         if (users)
1270                 goto out;
1271         e->len = e->end - e->offset;
1272         spin_unlock(&con->writequeue_lock);
1273
1274         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1275                 queue_work(send_workqueue, &con->swork);
1276         }
1277         return;
1278
1279 out:
1280         spin_unlock(&con->writequeue_lock);
1281         return;
1282 }
1283
1284 /* Send a message */
1285 static void send_to_sock(struct connection *con)
1286 {
1287         int ret = 0;
1288         ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
1289         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1290         struct writequeue_entry *e;
1291         int len, offset;
1292
1293         mutex_lock(&con->sock_mutex);
1294         if (con->sock == NULL)
1295                 goto out_connect;
1296
1297         sendpage = con->sock->ops->sendpage;
1298
1299         spin_lock(&con->writequeue_lock);
1300         for (;;) {
1301                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1302                                list);
1303                 if ((struct list_head *) e == &con->writequeue)
1304                         break;
1305
1306                 len = e->len;
1307                 offset = e->offset;
1308                 BUG_ON(len == 0 && e->users == 0);
1309                 spin_unlock(&con->writequeue_lock);
1310
1311                 ret = 0;
1312                 if (len) {
1313                         ret = sendpage(con->sock, e->page, offset, len,
1314                                        msg_flags);
1315                         if (ret == -EAGAIN || ret == 0) {
1316                                 cond_resched();
1317                                 goto out;
1318                         }
1319                         if (ret <= 0)
1320                                 goto send_error;
1321                 }
1322                         /* Don't starve people filling buffers */
1323                         cond_resched();
1324
1325                 spin_lock(&con->writequeue_lock);
1326                 e->offset += ret;
1327                 e->len -= ret;
1328
1329                 if (e->len == 0 && e->users == 0) {
1330                         list_del(&e->list);
1331                         free_entry(e);
1332                         continue;
1333                 }
1334         }
1335         spin_unlock(&con->writequeue_lock);
1336 out:
1337         mutex_unlock(&con->sock_mutex);
1338         return;
1339
1340 send_error:
1341         mutex_unlock(&con->sock_mutex);
1342         close_connection(con, false);
1343         lowcomms_connect_sock(con);
1344         return;
1345
1346 out_connect:
1347         mutex_unlock(&con->sock_mutex);
1348         if (!test_bit(CF_INIT_PENDING, &con->flags))
1349                 lowcomms_connect_sock(con);
1350         return;
1351 }
1352
1353 static void clean_one_writequeue(struct connection *con)
1354 {
1355         struct writequeue_entry *e, *safe;
1356
1357         spin_lock(&con->writequeue_lock);
1358         list_for_each_entry_safe(e, safe, &con->writequeue, list) {
1359                 list_del(&e->list);
1360                 free_entry(e);
1361         }
1362         spin_unlock(&con->writequeue_lock);
1363 }
1364
1365 /* Called from recovery when it knows that a node has
1366    left the cluster */
1367 int dlm_lowcomms_close(int nodeid)
1368 {
1369         struct connection *con;
1370
1371         log_print("closing connection to node %d", nodeid);
1372         con = nodeid2con(nodeid, 0);
1373         if (con) {
1374                 clear_bit(CF_CONNECT_PENDING, &con->flags);
1375                 clear_bit(CF_WRITE_PENDING, &con->flags);
1376                 set_bit(CF_CLOSE, &con->flags);
1377                 if (cancel_work_sync(&con->swork))
1378                         log_print("canceled swork for node %d", nodeid);
1379                 if (cancel_work_sync(&con->rwork))
1380                         log_print("canceled rwork for node %d", nodeid);
1381                 clean_one_writequeue(con);
1382                 close_connection(con, true);
1383         }
1384         return 0;
1385 }
1386
1387 /* Receive workqueue function */
1388 static void process_recv_sockets(struct work_struct *work)
1389 {
1390         struct connection *con = container_of(work, struct connection, rwork);
1391         int err;
1392
1393         clear_bit(CF_READ_PENDING, &con->flags);
1394         do {
1395                 err = con->rx_action(con);
1396         } while (!err);
1397 }
1398
1399 /* Send workqueue function */
1400 static void process_send_sockets(struct work_struct *work)
1401 {
1402         struct connection *con = container_of(work, struct connection, swork);
1403
1404         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1405                 con->connect_action(con);
1406                 set_bit(CF_WRITE_PENDING, &con->flags);
1407         }
1408         if (test_and_clear_bit(CF_WRITE_PENDING, &con->flags))
1409                 send_to_sock(con);
1410 }
1411
1412
1413 /* Discard all entries on the write queues */
1414 static void clean_writequeues(void)
1415 {
1416         foreach_conn(clean_one_writequeue);
1417 }
1418
1419 static void work_stop(void)
1420 {
1421         destroy_workqueue(recv_workqueue);
1422         destroy_workqueue(send_workqueue);
1423 }
1424
1425 static int work_start(void)
1426 {
1427         int error;
1428         recv_workqueue = create_workqueue("dlm_recv");
1429         error = IS_ERR(recv_workqueue);
1430         if (error) {
1431                 log_print("can't start dlm_recv %d", error);
1432                 return error;
1433         }
1434
1435         send_workqueue = create_singlethread_workqueue("dlm_send");
1436         error = IS_ERR(send_workqueue);
1437         if (error) {
1438                 log_print("can't start dlm_send %d", error);
1439                 destroy_workqueue(recv_workqueue);
1440                 return error;
1441         }
1442
1443         return 0;
1444 }
1445
1446 static void stop_conn(struct connection *con)
1447 {
1448         con->flags |= 0x0F;
1449         if (con->sock && con->sock->sk)
1450                 con->sock->sk->sk_user_data = NULL;
1451 }
1452
1453 static void free_conn(struct connection *con)
1454 {
1455         close_connection(con, true);
1456         if (con->othercon)
1457                 kmem_cache_free(con_cache, con->othercon);
1458         hlist_del(&con->list);
1459         kmem_cache_free(con_cache, con);
1460 }
1461
1462 void dlm_lowcomms_stop(void)
1463 {
1464         /* Set all the flags to prevent any
1465            socket activity.
1466         */
1467         mutex_lock(&connections_lock);
1468         foreach_conn(stop_conn);
1469         mutex_unlock(&connections_lock);
1470
1471         work_stop();
1472
1473         mutex_lock(&connections_lock);
1474         clean_writequeues();
1475
1476         foreach_conn(free_conn);
1477
1478         mutex_unlock(&connections_lock);
1479         kmem_cache_destroy(con_cache);
1480 }
1481
1482 int dlm_lowcomms_start(void)
1483 {
1484         int error = -EINVAL;
1485         struct connection *con;
1486         int i;
1487
1488         for (i = 0; i < CONN_HASH_SIZE; i++)
1489                 INIT_HLIST_HEAD(&connection_hash[i]);
1490
1491         init_local();
1492         if (!dlm_local_count) {
1493                 error = -ENOTCONN;
1494                 log_print("no local IP address has been set");
1495                 goto out;
1496         }
1497
1498         error = -ENOMEM;
1499         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1500                                       __alignof__(struct connection), 0,
1501                                       NULL);
1502         if (!con_cache)
1503                 goto out;
1504
1505         /* Start listening */
1506         if (dlm_config.ci_protocol == 0)
1507                 error = tcp_listen_for_all();
1508         else
1509                 error = sctp_listen_for_all();
1510         if (error)
1511                 goto fail_unlisten;
1512
1513         error = work_start();
1514         if (error)
1515                 goto fail_unlisten;
1516
1517         return 0;
1518
1519 fail_unlisten:
1520         con = nodeid2con(0,0);
1521         if (con) {
1522                 close_connection(con, false);
1523                 kmem_cache_free(con_cache, con);
1524         }
1525         kmem_cache_destroy(con_cache);
1526
1527 out:
1528         return error;
1529 }