Pileus Git - ~andy/linux/blob - 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 <linux/slab.h>
  55 #include <net/sctp/sctp.h>
  56 #include <net/sctp/user.h>
  57 #include <net/ipv6.h>
  58
  59 #include "dlm_internal.h"
  60 #include "lowcomms.h"
  61 #include "midcomms.h"
  62 #include "config.h"
  63
  64 #define NEEDED_RMEM (4*1024*1024)
  65 #define CONN_HASH_SIZE 32
  66
  67 /* Number of messages to send before rescheduling */
  68 #define MAX_SEND_MSG_COUNT 25
  69
  70 struct cbuf {
  71         unsigned int base;
  72         unsigned int len;
  73         unsigned int mask;
  74 };
  75
  76 static void cbuf_add(struct cbuf *cb, int n)
  77 {
  78         cb->len += n;
  79 }
  80
  81 static int cbuf_data(struct cbuf *cb)
  82 {
  83         return ((cb->base + cb->len) & cb->mask);
  84 }
  85
  86 static void cbuf_init(struct cbuf *cb, int size)
  87 {
  88         cb->base = cb->len = 0;
  89         cb->mask = size-1;
  90 }
  91
  92 static void cbuf_eat(struct cbuf *cb, int n)
  93 {
  94         cb->len  -= n;
  95         cb->base += n;
  96         cb->base &= cb->mask;
  97 }
  98
  99 static bool cbuf_empty(struct cbuf *cb)
 100 {
 101         return cb->len == 0;
 102 }
 103
 104 struct connection {
 105         struct socket *sock;    /* NULL if not connected */
 106         uint32_t nodeid;        /* So we know who we are in the list */
 107         struct mutex sock_mutex;
 108         unsigned long flags;
 109 #define CF_READ_PENDING 1
 110 #define CF_WRITE_PENDING 2
 111 #define CF_CONNECT_PENDING 3
 112 #define CF_INIT_PENDING 4
 113 #define CF_IS_OTHERCON 5
 114 #define CF_CLOSE 6
 115 #define CF_APP_LIMITED 7
 116         struct list_head writequeue;  /* List of outgoing writequeue_entries */
 117         spinlock_t writequeue_lock;
 118         int (*rx_action) (struct connection *); /* What to do when active */
 119         void (*connect_action) (struct connection *);   /* What to do to connect */
 120         struct page *rx_page;
 121         struct cbuf cb;
 122         int retries;
 123 #define MAX_CONNECT_RETRIES 3
 124         int sctp_assoc;
 125         struct hlist_node list;
 126         struct connection *othercon;
 127         struct work_struct rwork; /* Receive workqueue */
 128         struct work_struct swork; /* Send workqueue */
 129 };
 130 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
 131
 132 /* An entry waiting to be sent */
 133 struct writequeue_entry {
 134         struct list_head list;
 135         struct page *page;
 136         int offset;
 137         int len;
 138         int end;
 139         int users;
 140         struct connection *con;
 141 };
 142
 143 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 144 static int dlm_local_count;
 145
 146 /* Work queues */
 147 static struct workqueue_struct *recv_workqueue;
 148 static struct workqueue_struct *send_workqueue;
 149
 150 static struct hlist_head connection_hash[CONN_HASH_SIZE];
 151 static DEFINE_MUTEX(connections_lock);
 152 static struct kmem_cache *con_cache;
 153
 154 static void process_recv_sockets(struct work_struct *work);
 155 static void process_send_sockets(struct work_struct *work);
 156
 157
 158 /* This is deliberately very simple because most clusters have simple
 159    sequential nodeids, so we should be able to go straight to a connection
 160    struct in the array */
 161 static inline int nodeid_hash(int nodeid)
 162 {
 163         return nodeid & (CONN_HASH_SIZE-1);
 164 }
 165
 166 static struct connection *__find_con(int nodeid)
 167 {
 168         int r;
 169         struct hlist_node *h;
 170         struct connection *con;
 171
 172         r = nodeid_hash(nodeid);
 173
 174         hlist_for_each_entry(con, h, &connection_hash[r], list) {
 175                 if (con->nodeid == nodeid)
 176                         return con;
 177         }
 178         return NULL;
 179 }
 180
 181 /*
 182  * If 'allocation' is zero then we don't attempt to create a new
 183  * connection structure for this node.
 184  */
 185 static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
 186 {
 187         struct connection *con = NULL;
 188         int r;
 189
 190         con = __find_con(nodeid);
 191         if (con || !alloc)
 192                 return con;
 193
 194         con = kmem_cache_zalloc(con_cache, alloc);
 195         if (!con)
 196                 return NULL;
 197
 198         r = nodeid_hash(nodeid);
 199         hlist_add_head(&con->list, &connection_hash[r]);
 200
 201         con->nodeid = nodeid;
 202         mutex_init(&con->sock_mutex);
 203         INIT_LIST_HEAD(&con->writequeue);
 204         spin_lock_init(&con->writequeue_lock);
 205         INIT_WORK(&con->swork, process_send_sockets);
 206         INIT_WORK(&con->rwork, process_recv_sockets);
 207
 208         /* Setup action pointers for child sockets */
 209         if (con->nodeid) {
 210                 struct connection *zerocon = __find_con(0);
 211
 212                 con->connect_action = zerocon->connect_action;
 213                 if (!con->rx_action)
 214                         con->rx_action = zerocon->rx_action;
 215         }
 216
 217         return con;
 218 }
 219
 220 /* Loop round all connections */
 221 static void foreach_conn(void (*conn_func)(struct connection *c))
 222 {
 223         int i;
 224         struct hlist_node *h, *n;
 225         struct connection *con;
 226
 227         for (i = 0; i < CONN_HASH_SIZE; i++) {
 228                 hlist_for_each_entry_safe(con, h, n, &connection_hash[i], list){
 229                         conn_func(con);
 230                 }
 231         }
 232 }
 233
 234 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
 235 {
 236         struct connection *con;
 237
 238         mutex_lock(&connections_lock);
 239         con = __nodeid2con(nodeid, allocation);
 240         mutex_unlock(&connections_lock);
 241
 242         return con;
 243 }
 244
 245 /* This is a bit drastic, but only called when things go wrong */
 246 static struct connection *assoc2con(int assoc_id)
 247 {
 248         int i;
 249         struct hlist_node *h;
 250         struct connection *con;
 251
 252         mutex_lock(&connections_lock);
 253
 254         for (i = 0 ; i < CONN_HASH_SIZE; i++) {
 255                 hlist_for_each_entry(con, h, &connection_hash[i], list) {
 256                         if (con->sctp_assoc == assoc_id) {
 257                                 mutex_unlock(&connections_lock);
 258                                 return con;
 259                         }
 260                 }
 261         }
 262         mutex_unlock(&connections_lock);
 263         return NULL;
 264 }
 265
 266 static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
 267 {
 268         struct sockaddr_storage addr;
 269         int error;
 270
 271         if (!dlm_local_count)
 272                 return -1;
 273
 274         error = dlm_nodeid_to_addr(nodeid, &addr);
 275         if (error)
 276                 return error;
 277
 278         if (dlm_local_addr[0]->ss_family == AF_INET) {
 279                 struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
 280                 struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
 281                 ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
 282         } else {
 283                 struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
 284                 struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
 285                 ret6->sin6_addr = in6->sin6_addr;
 286         }
 287
 288         return 0;
 289 }
 290
 291 /* Data available on socket or listen socket received a connect */
 292 static void lowcomms_data_ready(struct sock *sk, int count_unused)
 293 {
 294         struct connection *con = sock2con(sk);
 295         if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
 296                 queue_work(recv_workqueue, &con->rwork);
 297 }
 298
 299 static void lowcomms_write_space(struct sock *sk)
 300 {
 301         struct connection *con = sock2con(sk);
 302
 303         if (!con)
 304                 return;
 305
 306         clear_bit(SOCK_NOSPACE, &con->sock->flags);
 307
 308         if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
 309                 con->sock->sk->sk_write_pending--;
 310                 clear_bit(SOCK_ASYNC_NOSPACE, &con->sock->flags);
 311         }
 312
 313         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 314                 queue_work(send_workqueue, &con->swork);
 315 }
 316
 317 static inline void lowcomms_connect_sock(struct connection *con)
 318 {
 319         if (test_bit(CF_CLOSE, &con->flags))
 320                 return;
 321         if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
 322                 queue_work(send_workqueue, &con->swork);
 323 }
 324
 325 static void lowcomms_state_change(struct sock *sk)
 326 {
 327         if (sk->sk_state == TCP_ESTABLISHED)
 328                 lowcomms_write_space(sk);
 329 }
 330
 331 int dlm_lowcomms_connect_node(int nodeid)
 332 {
 333         struct connection *con;
 334
 335         /* with sctp there's no connecting without sending */
 336         if (dlm_config.ci_protocol != 0)
 337                 return 0;
 338
 339         if (nodeid == dlm_our_nodeid())
 340                 return 0;
 341
 342         con = nodeid2con(nodeid, GFP_NOFS);
 343         if (!con)
 344                 return -ENOMEM;
 345         lowcomms_connect_sock(con);
 346         return 0;
 347 }
 348
 349 /* Make a socket active */
 350 static int add_sock(struct socket *sock, struct connection *con)
 351 {
 352         con->sock = sock;
 353
 354         /* Install a data_ready callback */
 355         con->sock->sk->sk_data_ready = lowcomms_data_ready;
 356         con->sock->sk->sk_write_space = lowcomms_write_space;
 357         con->sock->sk->sk_state_change = lowcomms_state_change;
 358         con->sock->sk->sk_user_data = con;
 359         con->sock->sk->sk_allocation = GFP_NOFS;
 360         return 0;
 361 }
 362
 363 /* Add the port number to an IPv6 or 4 sockaddr and return the address
 364    length */
 365 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 366                           int *addr_len)
 367 {
 368         saddr->ss_family =  dlm_local_addr[0]->ss_family;
 369         if (saddr->ss_family == AF_INET) {
 370                 struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
 371                 in4_addr->sin_port = cpu_to_be16(port);
 372                 *addr_len = sizeof(struct sockaddr_in);
 373                 memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
 374         } else {
 375                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
 376                 in6_addr->sin6_port = cpu_to_be16(port);
 377                 *addr_len = sizeof(struct sockaddr_in6);
 378         }
 379         memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
 380 }
 381
 382 /* Close a remote connection and tidy up */
 383 static void close_connection(struct connection *con, bool and_other)
 384 {
 385         mutex_lock(&con->sock_mutex);
 386
 387         if (con->sock) {
 388                 sock_release(con->sock);
 389                 con->sock = NULL;
 390         }
 391         if (con->othercon && and_other) {
 392                 /* Will only re-enter once. */
 393                 close_connection(con->othercon, false);
 394         }
 395         if (con->rx_page) {
 396                 __free_page(con->rx_page);
 397                 con->rx_page = NULL;
 398         }
 399
 400         con->retries = 0;
 401         mutex_unlock(&con->sock_mutex);
 402 }
 403
 404 /* We only send shutdown messages to nodes that are not part of the cluster */
 405 static void sctp_send_shutdown(sctp_assoc_t associd)
 406 {
 407         static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 408         struct msghdr outmessage;
 409         struct cmsghdr *cmsg;
 410         struct sctp_sndrcvinfo *sinfo;
 411         int ret;
 412         struct connection *con;
 413
 414         con = nodeid2con(0,0);
 415         BUG_ON(con == NULL);
 416
 417         outmessage.msg_name = NULL;
 418         outmessage.msg_namelen = 0;
 419         outmessage.msg_control = outcmsg;
 420         outmessage.msg_controllen = sizeof(outcmsg);
 421         outmessage.msg_flags = MSG_EOR;
 422
 423         cmsg = CMSG_FIRSTHDR(&outmessage);
 424         cmsg->cmsg_level = IPPROTO_SCTP;
 425         cmsg->cmsg_type = SCTP_SNDRCV;
 426         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 427         outmessage.msg_controllen = cmsg->cmsg_len;
 428         sinfo = CMSG_DATA(cmsg);
 429         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 430
 431         sinfo->sinfo_flags |= MSG_EOF;
 432         sinfo->sinfo_assoc_id = associd;
 433
 434         ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);
 435
 436         if (ret != 0)
 437                 log_print("send EOF to node failed: %d", ret);
 438 }
 439
 440 static void sctp_init_failed_foreach(struct connection *con)
 441 {
 442         con->sctp_assoc = 0;
 443         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
 444                 if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 445                         queue_work(send_workqueue, &con->swork);
 446         }
 447 }
 448
 449 /* INIT failed but we don't know which node...
 450    restart INIT on all pending nodes */
 451 static void sctp_init_failed(void)
 452 {
 453         mutex_lock(&connections_lock);
 454
 455         foreach_conn(sctp_init_failed_foreach);
 456
 457         mutex_unlock(&connections_lock);
 458 }
 459
 460 /* Something happened to an association */
 461 static void process_sctp_notification(struct connection *con,
 462                                       struct msghdr *msg, char *buf)
 463 {
 464         union sctp_notification *sn = (union sctp_notification *)buf;
 465
 466         if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
 467                 switch (sn->sn_assoc_change.sac_state) {
 468
 469                 case SCTP_COMM_UP:
 470                 case SCTP_RESTART:
 471                 {
 472                         /* Check that the new node is in the lockspace */
 473                         struct sctp_prim prim;
 474                         int nodeid;
 475                         int prim_len, ret;
 476                         int addr_len;
 477                         struct connection *new_con;
 478
 479                         /*
 480                          * We get this before any data for an association.
 481                          * We verify that the node is in the cluster and
 482                          * then peel off a socket for it.
 483                          */
 484                         if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
 485                                 log_print("COMM_UP for invalid assoc ID %d",
 486                                          (int)sn->sn_assoc_change.sac_assoc_id);
 487                                 sctp_init_failed();
 488                                 return;
 489                         }
 490                         memset(&prim, 0, sizeof(struct sctp_prim));
 491                         prim_len = sizeof(struct sctp_prim);
 492                         prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
 493
 494                         ret = kernel_getsockopt(con->sock,
 495                                                 IPPROTO_SCTP,
 496                                                 SCTP_PRIMARY_ADDR,
 497                                                 (char*)&prim,
 498                                                 &prim_len);
 499                         if (ret < 0) {
 500                                 log_print("getsockopt/sctp_primary_addr on "
 501                                           "new assoc %d failed : %d",
 502                                           (int)sn->sn_assoc_change.sac_assoc_id,
 503                                           ret);
 504
 505                                 /* Retry INIT later */
 506                                 new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 507                                 if (new_con)
 508                                         clear_bit(CF_CONNECT_PENDING, &con->flags);
 509                                 return;
 510                         }
 511                         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
 512                         if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
 513                                 unsigned char *b=(unsigned char *)&prim.ssp_addr;
 514                                 log_print("reject connect from unknown addr");
 515                                 print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE,
 516                                                      b, sizeof(struct sockaddr_storage));
 517                                 sctp_send_shutdown(prim.ssp_assoc_id);
 518                                 return;
 519                         }
 520
 521                         new_con = nodeid2con(nodeid, GFP_NOFS);
 522                         if (!new_con)
 523                                 return;
 524
 525                         /* Peel off a new sock */
 526                         sctp_lock_sock(con->sock->sk);
 527                         ret = sctp_do_peeloff(con->sock->sk,
 528                                 sn->sn_assoc_change.sac_assoc_id,
 529                                 &new_con->sock);
 530                         sctp_release_sock(con->sock->sk);
 531                         if (ret < 0) {
 532                                 log_print("Can't peel off a socket for "
 533                                           "connection %d to node %d: err=%d",
 534                                           (int)sn->sn_assoc_change.sac_assoc_id,
 535                                           nodeid, ret);
 536                                 return;
 537                         }
 538                         add_sock(new_con->sock, new_con);
 539
 540                         log_print("connecting to %d sctp association %d",
 541                                  nodeid, (int)sn->sn_assoc_change.sac_assoc_id);
 542
 543                         /* Send any pending writes */
 544                         clear_bit(CF_CONNECT_PENDING, &new_con->flags);
 545                         clear_bit(CF_INIT_PENDING, &con->flags);
 546                         if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
 547                                 queue_work(send_workqueue, &new_con->swork);
 548                         }
 549                         if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))
 550                                 queue_work(recv_workqueue, &new_con->rwork);
 551                 }
 552                 break;
 553
 554                 case SCTP_COMM_LOST:
 555                 case SCTP_SHUTDOWN_COMP:
 556                 {
 557                         con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 558                         if (con) {
 559                                 con->sctp_assoc = 0;
 560                         }
 561                 }
 562                 break;
 563
 564                 /* We don't know which INIT failed, so clear the PENDING flags
 565                  * on them all.  if assoc_id is zero then it will then try
 566                  * again */
 567
 568                 case SCTP_CANT_STR_ASSOC:
 569                 {
 570                         log_print("Can't start SCTP association - retrying");
 571                         sctp_init_failed();
 572                 }
 573                 break;
 574
 575                 default:
 576                         log_print("unexpected SCTP assoc change id=%d state=%d",
 577                                   (int)sn->sn_assoc_change.sac_assoc_id,
 578                                   sn->sn_assoc_change.sac_state);
 579                 }
 580         }
 581 }
 582
 583 /* Data received from remote end */
 584 static int receive_from_sock(struct connection *con)
 585 {
 586         int ret = 0;
 587         struct msghdr msg = {};
 588         struct kvec iov[2];
 589         unsigned len;
 590         int r;
 591         int call_again_soon = 0;
 592         int nvec;
 593         char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 594
 595         mutex_lock(&con->sock_mutex);
 596
 597         if (con->sock == NULL) {
 598                 ret = -EAGAIN;
 599                 goto out_close;
 600         }
 601
 602         if (con->rx_page == NULL) {
 603                 /*
 604                  * This doesn't need to be atomic, but I think it should
 605                  * improve performance if it is.
 606                  */
 607                 con->rx_page = alloc_page(GFP_ATOMIC);
 608                 if (con->rx_page == NULL)
 609                         goto out_resched;
 610                 cbuf_init(&con->cb, PAGE_CACHE_SIZE);
 611         }
 612
 613         /* Only SCTP needs these really */
 614         memset(&incmsg, 0, sizeof(incmsg));
 615         msg.msg_control = incmsg;
 616         msg.msg_controllen = sizeof(incmsg);
 617
 618         /*
 619          * iov[0] is the bit of the circular buffer between the current end
 620          * point (cb.base + cb.len) and the end of the buffer.
 621          */
 622         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
 623         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
 624         iov[1].iov_len = 0;
 625         nvec = 1;
 626
 627         /*
 628          * iov[1] is the bit of the circular buffer between the start of the
 629          * buffer and the start of the currently used section (cb.base)
 630          */
 631         if (cbuf_data(&con->cb) >= con->cb.base) {
 632                 iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
 633                 iov[1].iov_len = con->cb.base;
 634                 iov[1].iov_base = page_address(con->rx_page);
 635                 nvec = 2;
 636         }
 637         len = iov[0].iov_len + iov[1].iov_len;
 638
 639         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
 640                                MSG_DONTWAIT | MSG_NOSIGNAL);
 641         if (ret <= 0)
 642                 goto out_close;
 643
 644         /* Process SCTP notifications */
 645         if (msg.msg_flags & MSG_NOTIFICATION) {
 646                 msg.msg_control = incmsg;
 647                 msg.msg_controllen = sizeof(incmsg);
 648
 649                 process_sctp_notification(con, &msg,
 650                                 page_address(con->rx_page) + con->cb.base);
 651                 mutex_unlock(&con->sock_mutex);
 652                 return 0;
 653         }
 654         BUG_ON(con->nodeid == 0);
 655
 656         if (ret == len)
 657                 call_again_soon = 1;
 658         cbuf_add(&con->cb, ret);
 659         ret = dlm_process_incoming_buffer(con->nodeid,
 660                                           page_address(con->rx_page),
 661                                           con->cb.base, con->cb.len,
 662                                           PAGE_CACHE_SIZE);
 663         if (ret == -EBADMSG) {
 664                 log_print("lowcomms: addr=%p, base=%u, len=%u, "
 665                           "iov_len=%u, iov_base[0]=%p, read=%d",
 666                           page_address(con->rx_page), con->cb.base, con->cb.len,
 667                           len, iov[0].iov_base, r);
 668         }
 669         if (ret < 0)
 670                 goto out_close;
 671         cbuf_eat(&con->cb, ret);
 672
 673         if (cbuf_empty(&con->cb) && !call_again_soon) {
 674                 __free_page(con->rx_page);
 675                 con->rx_page = NULL;
 676         }
 677
 678         if (call_again_soon)
 679                 goto out_resched;
 680         mutex_unlock(&con->sock_mutex);
 681         return 0;
 682
 683 out_resched:
 684         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
 685                 queue_work(recv_workqueue, &con->rwork);
 686         mutex_unlock(&con->sock_mutex);
 687         return -EAGAIN;
 688
 689 out_close:
 690         mutex_unlock(&con->sock_mutex);
 691         if (ret != -EAGAIN) {
 692                 close_connection(con, false);
 693                 /* Reconnect when there is something to send */
 694         }
 695         /* Don't return success if we really got EOF */
 696         if (ret == 0)
 697                 ret = -EAGAIN;
 698
 699         return ret;
 700 }
 701
 702 /* Listening socket is busy, accept a connection */
 703 static int tcp_accept_from_sock(struct connection *con)
 704 {
 705         int result;
 706         struct sockaddr_storage peeraddr;
 707         struct socket *newsock;
 708         int len;
 709         int nodeid;
 710         struct connection *newcon;
 711         struct connection *addcon;
 712
 713         memset(&peeraddr, 0, sizeof(peeraddr));
 714         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 715                                   IPPROTO_TCP, &newsock);
 716         if (result < 0)
 717                 return -ENOMEM;
 718
 719         mutex_lock_nested(&con->sock_mutex, 0);
 720
 721         result = -ENOTCONN;
 722         if (con->sock == NULL)
 723                 goto accept_err;
 724
 725         newsock->type = con->sock->type;
 726         newsock->ops = con->sock->ops;
 727
 728         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
 729         if (result < 0)
 730                 goto accept_err;
 731
 732         /* Get the connected socket's peer */
 733         memset(&peeraddr, 0, sizeof(peeraddr));
 734         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
 735                                   &len, 2)) {
 736                 result = -ECONNABORTED;
 737                 goto accept_err;
 738         }
 739
 740         /* Get the new node's NODEID */
 741         make_sockaddr(&peeraddr, 0, &len);
 742         if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
 743                 unsigned char *b=(unsigned char *)&peeraddr;
 744                 log_print("connect from non cluster node");
 745                 print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE,
 746                                      b, sizeof(struct sockaddr_storage));
 747                 sock_release(newsock);
 748                 mutex_unlock(&con->sock_mutex);
 749                 return -1;
 750         }
 751
 752         log_print("got connection from %d", nodeid);
 753
 754         /*  Check to see if we already have a connection to this node. This
 755          *  could happen if the two nodes initiate a connection at roughly
 756          *  the same time and the connections cross on the wire.
 757          *  In this case we store the incoming one in "othercon"
 758          */
 759         newcon = nodeid2con(nodeid, GFP_NOFS);
 760         if (!newcon) {
 761                 result = -ENOMEM;
 762                 goto accept_err;
 763         }
 764         mutex_lock_nested(&newcon->sock_mutex, 1);
 765         if (newcon->sock) {
 766                 struct connection *othercon = newcon->othercon;
 767
 768                 if (!othercon) {
 769                         othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
 770                         if (!othercon) {
 771                                 log_print("failed to allocate incoming socket");
 772                                 mutex_unlock(&newcon->sock_mutex);
 773                                 result = -ENOMEM;
 774                                 goto accept_err;
 775                         }
 776                         othercon->nodeid = nodeid;
 777                         othercon->rx_action = receive_from_sock;
 778                         mutex_init(&othercon->sock_mutex);
 779                         INIT_WORK(&othercon->swork, process_send_sockets);
 780                         INIT_WORK(&othercon->rwork, process_recv_sockets);
 781                         set_bit(CF_IS_OTHERCON, &othercon->flags);
 782                 }
 783                 if (!othercon->sock) {
 784                         newcon->othercon = othercon;
 785                         othercon->sock = newsock;
 786                         newsock->sk->sk_user_data = othercon;
 787                         add_sock(newsock, othercon);
 788                         addcon = othercon;
 789                 }
 790                 else {
 791                         printk("Extra connection from node %d attempted\n", nodeid);
 792                         result = -EAGAIN;
 793                         mutex_unlock(&newcon->sock_mutex);
 794                         goto accept_err;
 795                 }
 796         }
 797         else {
 798                 newsock->sk->sk_user_data = newcon;
 799                 newcon->rx_action = receive_from_sock;
 800                 add_sock(newsock, newcon);
 801                 addcon = newcon;
 802         }
 803
 804         mutex_unlock(&newcon->sock_mutex);
 805
 806         /*
 807          * Add it to the active queue in case we got data
 808          * between processing the accept adding the socket
 809          * to the read_sockets list
 810          */
 811         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
 812                 queue_work(recv_workqueue, &addcon->rwork);
 813         mutex_unlock(&con->sock_mutex);
 814
 815         return 0;
 816
 817 accept_err:
 818         mutex_unlock(&con->sock_mutex);
 819         sock_release(newsock);
 820
 821         if (result != -EAGAIN)
 822                 log_print("error accepting connection from node: %d", result);
 823         return result;
 824 }
 825
 826 static void free_entry(struct writequeue_entry *e)
 827 {
 828         __free_page(e->page);
 829         kfree(e);
 830 }
 831
 832 /* Initiate an SCTP association.
 833    This is a special case of send_to_sock() in that we don't yet have a
 834    peeled-off socket for this association, so we use the listening socket
 835    and add the primary IP address of the remote node.
 836  */
 837 static void sctp_init_assoc(struct connection *con)
 838 {
 839         struct sockaddr_storage rem_addr;
 840         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 841         struct msghdr outmessage;
 842         struct cmsghdr *cmsg;
 843         struct sctp_sndrcvinfo *sinfo;
 844         struct connection *base_con;
 845         struct writequeue_entry *e;
 846         int len, offset;
 847         int ret;
 848         int addrlen;
 849         struct kvec iov[1];
 850
 851         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
 852                 return;
 853
 854         if (con->retries++ > MAX_CONNECT_RETRIES)
 855                 return;
 856
 857         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
 858                 log_print("no address for nodeid %d", con->nodeid);
 859                 return;
 860         }
 861         base_con = nodeid2con(0, 0);
 862         BUG_ON(base_con == NULL);
 863
 864         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
 865
 866         outmessage.msg_name = &rem_addr;
 867         outmessage.msg_namelen = addrlen;
 868         outmessage.msg_control = outcmsg;
 869         outmessage.msg_controllen = sizeof(outcmsg);
 870         outmessage.msg_flags = MSG_EOR;
 871
 872         spin_lock(&con->writequeue_lock);
 873
 874         if (list_empty(&con->writequeue)) {
 875                 spin_unlock(&con->writequeue_lock);
 876                 log_print("writequeue empty for nodeid %d", con->nodeid);
 877                 return;
 878         }
 879
 880         e = list_first_entry(&con->writequeue, struct writequeue_entry, list);
 881         len = e->len;
 882         offset = e->offset;
 883         spin_unlock(&con->writequeue_lock);
 884
 885         /* Send the first block off the write queue */
 886         iov[0].iov_base = page_address(e->page)+offset;
 887         iov[0].iov_len = len;
 888
 889         cmsg = CMSG_FIRSTHDR(&outmessage);
 890         cmsg->cmsg_level = IPPROTO_SCTP;
 891         cmsg->cmsg_type = SCTP_SNDRCV;
 892         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 893         sinfo = CMSG_DATA(cmsg);
 894         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 895         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
 896         outmessage.msg_controllen = cmsg->cmsg_len;
 897
 898         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
 899         if (ret < 0) {
 900                 log_print("Send first packet to node %d failed: %d",
 901                           con->nodeid, ret);
 902
 903                 /* Try again later */
 904                 clear_bit(CF_CONNECT_PENDING, &con->flags);
 905                 clear_bit(CF_INIT_PENDING, &con->flags);
 906         }
 907         else {
 908                 spin_lock(&con->writequeue_lock);
 909                 e->offset += ret;
 910                 e->len -= ret;
 911
 912                 if (e->len == 0 && e->users == 0) {
 913                         list_del(&e->list);
 914                         free_entry(e);
 915                 }
 916                 spin_unlock(&con->writequeue_lock);
 917         }
 918 }
 919
 920 /* Connect a new socket to its peer */
 921 static void tcp_connect_to_sock(struct connection *con)
 922 {
 923         int result = -EHOSTUNREACH;
 924         struct sockaddr_storage saddr, src_addr;
 925         int addr_len;
 926         struct socket *sock = NULL;
 927         int one = 1;
 928
 929         if (con->nodeid == 0) {
 930                 log_print("attempt to connect sock 0 foiled");
 931                 return;
 932         }
 933
 934         mutex_lock(&con->sock_mutex);
 935         if (con->retries++ > MAX_CONNECT_RETRIES)
 936                 goto out;
 937
 938         /* Some odd races can cause double-connects, ignore them */
 939         if (con->sock) {
 940                 result = 0;
 941                 goto out;
 942         }
 943
 944         /* Create a socket to communicate with */
 945         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 946                                   IPPROTO_TCP, &sock);
 947         if (result < 0)
 948                 goto out_err;
 949
 950         memset(&saddr, 0, sizeof(saddr));
 951         if (dlm_nodeid_to_addr(con->nodeid, &saddr))
 952                 goto out_err;
 953
 954         sock->sk->sk_user_data = con;
 955         con->rx_action = receive_from_sock;
 956         con->connect_action = tcp_connect_to_sock;
 957         add_sock(sock, con);
 958
 959         /* Bind to our cluster-known address connecting to avoid
 960            routing problems */
 961         memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
 962         make_sockaddr(&src_addr, 0, &addr_len);
 963         result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
 964                                  addr_len);
 965         if (result < 0) {
 966                 log_print("could not bind for connect: %d", result);
 967                 /* This *may* not indicate a critical error */
 968         }
 969
 970         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 971
 972         log_print("connecting to %d", con->nodeid);
 973
 974         /* Turn off Nagle's algorithm */
 975         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
 976                           sizeof(one));
 977
 978         result =
 979                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 980                                    O_NONBLOCK);
 981         if (result == -EINPROGRESS)
 982                 result = 0;
 983         if (result == 0)
 984                 goto out;
 985
 986 out_err:
 987         if (con->sock) {
 988                 sock_release(con->sock);
 989                 con->sock = NULL;
 990         } else if (sock) {
 991                 sock_release(sock);
 992         }
 993         /*
 994          * Some errors are fatal and this list might need adjusting. For other
 995          * errors we try again until the max number of retries is reached.
 996          */
 997         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
 998             result != -ENETDOWN && result != -EINVAL
 999             && result != -EPROTONOSUPPORT) {
1000                 lowcomms_connect_sock(con);
1001                 result = 0;
1002         }
1003 out:
1004         mutex_unlock(&con->sock_mutex);
1005         return;
1006 }
1007
1008 static struct socket *tcp_create_listen_sock(struct connection *con,
1009                                              struct sockaddr_storage *saddr)
1010 {
1011         struct socket *sock = NULL;
1012         int result = 0;
1013         int one = 1;
1014         int addr_len;
1015
1016         if (dlm_local_addr[0]->ss_family == AF_INET)
1017                 addr_len = sizeof(struct sockaddr_in);
1018         else
1019                 addr_len = sizeof(struct sockaddr_in6);
1020
1021         /* Create a socket to communicate with */
1022         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
1023                                   IPPROTO_TCP, &sock);
1024         if (result < 0) {
1025                 log_print("Can't create listening comms socket");
1026                 goto create_out;
1027         }
1028
1029         /* Turn off Nagle's algorithm */
1030         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
1031                           sizeof(one));
1032
1033         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
1034                                    (char *)&one, sizeof(one));
1035
1036         if (result < 0) {
1037                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
1038         }
1039         sock->sk->sk_user_data = con;
1040         con->rx_action = tcp_accept_from_sock;
1041         con->connect_action = tcp_connect_to_sock;
1042         con->sock = sock;
1043
1044         /* Bind to our port */
1045         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
1046         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
1047         if (result < 0) {
1048                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
1049                 sock_release(sock);
1050                 sock = NULL;
1051                 con->sock = NULL;
1052                 goto create_out;
1053         }
1054         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
1055                                  (char *)&one, sizeof(one));
1056         if (result < 0) {
1057                 log_print("Set keepalive failed: %d", result);
1058         }
1059
1060         result = sock->ops->listen(sock, 5);
1061         if (result < 0) {
1062                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
1063                 sock_release(sock);
1064                 sock = NULL;
1065                 goto create_out;
1066         }
1067
1068 create_out:
1069         return sock;
1070 }
1071
1072 /* Get local addresses */
1073 static void init_local(void)
1074 {
1075         struct sockaddr_storage sas, *addr;
1076         int i;
1077
1078         dlm_local_count = 0;
1079         for (i = 0; i < DLM_MAX_ADDR_COUNT; i++) {
1080                 if (dlm_our_addr(&sas, i))
1081                         break;
1082
1083                 addr = kmalloc(sizeof(*addr), GFP_NOFS);
1084                 if (!addr)
1085                         break;
1086                 memcpy(addr, &sas, sizeof(*addr));
1087                 dlm_local_addr[dlm_local_count++] = addr;
1088         }
1089 }
1090
1091 /* Bind to an IP address. SCTP allows multiple address so it can do
1092    multi-homing */
1093 static int add_sctp_bind_addr(struct connection *sctp_con,
1094                               struct sockaddr_storage *addr,
1095                               int addr_len, int num)
1096 {
1097         int result = 0;
1098
1099         if (num == 1)
1100                 result = kernel_bind(sctp_con->sock,
1101                                      (struct sockaddr *) addr,
1102                                      addr_len);
1103         else
1104                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1105                                            SCTP_SOCKOPT_BINDX_ADD,
1106                                            (char *)addr, addr_len);
1107
1108         if (result < 0)
1109                 log_print("Can't bind to port %d addr number %d",
1110                           dlm_config.ci_tcp_port, num);
1111
1112         return result;
1113 }
1114
1115 /* Initialise SCTP socket and bind to all interfaces */
1116 static int sctp_listen_for_all(void)
1117 {
1118         struct socket *sock = NULL;
1119         struct sockaddr_storage localaddr;
1120         struct sctp_event_subscribe subscribe;
1121         int result = -EINVAL, num = 1, i, addr_len;
1122         struct connection *con = nodeid2con(0, GFP_NOFS);
1123         int bufsize = NEEDED_RMEM;
1124
1125         if (!con)
1126                 return -ENOMEM;
1127
1128         log_print("Using SCTP for communications");
1129
1130         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1131                                   IPPROTO_SCTP, &sock);
1132         if (result < 0) {
1133                 log_print("Can't create comms socket, check SCTP is loaded");
1134                 goto out;
1135         }
1136
1137         /* Listen for events */
1138         memset(&subscribe, 0, sizeof(subscribe));
1139         subscribe.sctp_data_io_event = 1;
1140         subscribe.sctp_association_event = 1;
1141         subscribe.sctp_send_failure_event = 1;
1142         subscribe.sctp_shutdown_event = 1;
1143         subscribe.sctp_partial_delivery_event = 1;
1144
1145         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
1146                                  (char *)&bufsize, sizeof(bufsize));
1147         if (result)
1148                 log_print("Error increasing buffer space on socket %d", result);
1149
1150         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1151                                    (char *)&subscribe, sizeof(subscribe));
1152         if (result < 0) {
1153                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1154                           result);
1155                 goto create_delsock;
1156         }
1157
1158         /* Init con struct */
1159         sock->sk->sk_user_data = con;
1160         con->sock = sock;
1161         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1162         con->rx_action = receive_from_sock;
1163         con->connect_action = sctp_init_assoc;
1164
1165         /* Bind to all interfaces. */
1166         for (i = 0; i < dlm_local_count; i++) {
1167                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1168                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1169
1170                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1171                 if (result)
1172                         goto create_delsock;
1173                 ++num;
1174         }
1175
1176         result = sock->ops->listen(sock, 5);
1177         if (result < 0) {
1178                 log_print("Can't set socket listening");
1179                 goto create_delsock;
1180         }
1181
1182         return 0;
1183
1184 create_delsock:
1185         sock_release(sock);
1186         con->sock = NULL;
1187 out:
1188         return result;
1189 }
1190
1191 static int tcp_listen_for_all(void)
1192 {
1193         struct socket *sock = NULL;
1194         struct connection *con = nodeid2con(0, GFP_NOFS);
1195         int result = -EINVAL;
1196
1197         if (!con)
1198                 return -ENOMEM;
1199
1200         /* We don't support multi-homed hosts */
1201         if (dlm_local_addr[1] != NULL) {
1202                 log_print("TCP protocol can't handle multi-homed hosts, "
1203                           "try SCTP");
1204                 return -EINVAL;
1205         }
1206
1207         log_print("Using TCP for communications");
1208
1209         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1210         if (sock) {
1211                 add_sock(sock, con);
1212                 result = 0;
1213         }
1214         else {
1215                 result = -EADDRINUSE;
1216         }
1217
1218         return result;
1219 }
1220
1221
1222
1223 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1224                                                      gfp_t allocation)
1225 {
1226         struct writequeue_entry *entry;
1227
1228         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1229         if (!entry)
1230                 return NULL;
1231
1232         entry->page = alloc_page(allocation);
1233         if (!entry->page) {
1234                 kfree(entry);
1235                 return NULL;
1236         }
1237
1238         entry->offset = 0;
1239         entry->len = 0;
1240         entry->end = 0;
1241         entry->users = 0;
1242         entry->con = con;
1243
1244         return entry;
1245 }
1246
1247 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1248 {
1249         struct connection *con;
1250         struct writequeue_entry *e;
1251         int offset = 0;
1252         int users = 0;
1253
1254         con = nodeid2con(nodeid, allocation);
1255         if (!con)
1256                 return NULL;
1257
1258         spin_lock(&con->writequeue_lock);
1259         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1260         if ((&e->list == &con->writequeue) ||
1261             (PAGE_CACHE_SIZE - e->end < len)) {
1262                 e = NULL;
1263         } else {
1264                 offset = e->end;
1265                 e->end += len;
1266                 users = e->users++;
1267         }
1268         spin_unlock(&con->writequeue_lock);
1269
1270         if (e) {
1271         got_one:
1272                 *ppc = page_address(e->page) + offset;
1273                 return e;
1274         }
1275
1276         e = new_writequeue_entry(con, allocation);
1277         if (e) {
1278                 spin_lock(&con->writequeue_lock);
1279                 offset = e->end;
1280                 e->end += len;
1281                 users = e->users++;
1282                 list_add_tail(&e->list, &con->writequeue);
1283                 spin_unlock(&con->writequeue_lock);
1284                 goto got_one;
1285         }
1286         return NULL;
1287 }
1288
1289 void dlm_lowcomms_commit_buffer(void *mh)
1290 {
1291         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1292         struct connection *con = e->con;
1293         int users;
1294
1295         spin_lock(&con->writequeue_lock);
1296         users = --e->users;
1297         if (users)
1298                 goto out;
1299         e->len = e->end - e->offset;
1300         spin_unlock(&con->writequeue_lock);
1301
1302         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1303                 queue_work(send_workqueue, &con->swork);
1304         }
1305         return;
1306
1307 out:
1308         spin_unlock(&con->writequeue_lock);
1309         return;
1310 }
1311
1312 /* Send a message */
1313 static void send_to_sock(struct connection *con)
1314 {
1315         int ret = 0;
1316         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1317         struct writequeue_entry *e;
1318         int len, offset;
1319         int count = 0;
1320
1321         mutex_lock(&con->sock_mutex);
1322         if (con->sock == NULL)
1323                 goto out_connect;
1324
1325         spin_lock(&con->writequeue_lock);
1326         for (;;) {
1327                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1328                                list);
1329                 if ((struct list_head *) e == &con->writequeue)
1330                         break;
1331
1332                 len = e->len;
1333                 offset = e->offset;
1334                 BUG_ON(len == 0 && e->users == 0);
1335                 spin_unlock(&con->writequeue_lock);
1336
1337                 ret = 0;
1338                 if (len) {
1339                         ret = kernel_sendpage(con->sock, e->page, offset, len,
1340                                               msg_flags);
1341                         if (ret == -EAGAIN || ret == 0) {
1342                                 if (ret == -EAGAIN &&
1343                                     test_bit(SOCK_ASYNC_NOSPACE, &con->sock->flags) &&
1344                                     !test_and_set_bit(CF_APP_LIMITED, &con->flags)) {
1345                                         /* Notify TCP that we're limited by the
1346                                          * application window size.
1347                                          */
1348                                         set_bit(SOCK_NOSPACE, &con->sock->flags);
1349                                         con->sock->sk->sk_write_pending++;
1350                                 }
1351                                 cond_resched();
1352                                 goto out;
1353                         }
1354                         if (ret <= 0)
1355                                 goto send_error;
1356                 }
1357
1358                 /* Don't starve people filling buffers */
1359                 if (++count >= MAX_SEND_MSG_COUNT) {
1360                         cond_resched();
1361                         count = 0;
1362                 }
1363
1364                 spin_lock(&con->writequeue_lock);
1365                 e->offset += ret;
1366                 e->len -= ret;
1367
1368                 if (e->len == 0 && e->users == 0) {
1369                         list_del(&e->list);
1370                         free_entry(e);
1371                         continue;
1372                 }
1373         }
1374         spin_unlock(&con->writequeue_lock);
1375 out:
1376         mutex_unlock(&con->sock_mutex);
1377         return;
1378
1379 send_error:
1380         mutex_unlock(&con->sock_mutex);
1381         close_connection(con, false);
1382         lowcomms_connect_sock(con);
1383         return;
1384
1385 out_connect:
1386         mutex_unlock(&con->sock_mutex);
1387         if (!test_bit(CF_INIT_PENDING, &con->flags))
1388                 lowcomms_connect_sock(con);
1389         return;
1390 }
1391
1392 static void clean_one_writequeue(struct connection *con)
1393 {
1394         struct writequeue_entry *e, *safe;
1395
1396         spin_lock(&con->writequeue_lock);
1397         list_for_each_entry_safe(e, safe, &con->writequeue, list) {
1398                 list_del(&e->list);
1399                 free_entry(e);
1400         }
1401         spin_unlock(&con->writequeue_lock);
1402 }
1403
1404 /* Called from recovery when it knows that a node has
1405    left the cluster */
1406 int dlm_lowcomms_close(int nodeid)
1407 {
1408         struct connection *con;
1409
1410         log_print("closing connection to node %d", nodeid);
1411         con = nodeid2con(nodeid, 0);
1412         if (con) {
1413                 clear_bit(CF_CONNECT_PENDING, &con->flags);
1414                 clear_bit(CF_WRITE_PENDING, &con->flags);
1415                 set_bit(CF_CLOSE, &con->flags);
1416                 if (cancel_work_sync(&con->swork))
1417                         log_print("canceled swork for node %d", nodeid);
1418                 if (cancel_work_sync(&con->rwork))
1419                         log_print("canceled rwork for node %d", nodeid);
1420                 clean_one_writequeue(con);
1421                 close_connection(con, true);
1422         }
1423         return 0;
1424 }
1425
1426 /* Receive workqueue function */
1427 static void process_recv_sockets(struct work_struct *work)
1428 {
1429         struct connection *con = container_of(work, struct connection, rwork);
1430         int err;
1431
1432         clear_bit(CF_READ_PENDING, &con->flags);
1433         do {
1434                 err = con->rx_action(con);
1435         } while (!err);
1436 }
1437
1438 /* Send workqueue function */
1439 static void process_send_sockets(struct work_struct *work)
1440 {
1441         struct connection *con = container_of(work, struct connection, swork);
1442
1443         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1444                 con->connect_action(con);
1445                 set_bit(CF_WRITE_PENDING, &con->flags);
1446         }
1447         if (test_and_clear_bit(CF_WRITE_PENDING, &con->flags))
1448                 send_to_sock(con);
1449 }
1450
1451
1452 /* Discard all entries on the write queues */
1453 static void clean_writequeues(void)
1454 {
1455         foreach_conn(clean_one_writequeue);
1456 }
1457
1458 static void work_stop(void)
1459 {
1460         destroy_workqueue(recv_workqueue);
1461         destroy_workqueue(send_workqueue);
1462 }
1463
1464 static int work_start(void)
1465 {
1466         recv_workqueue = alloc_workqueue("dlm_recv",
1467                                          WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
1468         if (!recv_workqueue) {
1469                 log_print("can't start dlm_recv");
1470                 return -ENOMEM;
1471         }
1472
1473         send_workqueue = alloc_workqueue("dlm_send",
1474                                          WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
1475         if (!send_workqueue) {
1476                 log_print("can't start dlm_send");
1477                 destroy_workqueue(recv_workqueue);
1478                 return -ENOMEM;
1479         }
1480
1481         return 0;
1482 }
1483
1484 static void stop_conn(struct connection *con)
1485 {
1486         con->flags |= 0x0F;
1487         if (con->sock && con->sock->sk)
1488                 con->sock->sk->sk_user_data = NULL;
1489 }
1490
1491 static void free_conn(struct connection *con)
1492 {
1493         close_connection(con, true);
1494         if (con->othercon)
1495                 kmem_cache_free(con_cache, con->othercon);
1496         hlist_del(&con->list);
1497         kmem_cache_free(con_cache, con);
1498 }
1499
1500 void dlm_lowcomms_stop(void)
1501 {
1502         /* Set all the flags to prevent any
1503            socket activity.
1504         */
1505         mutex_lock(&connections_lock);
1506         foreach_conn(stop_conn);
1507         mutex_unlock(&connections_lock);
1508
1509         work_stop();
1510
1511         mutex_lock(&connections_lock);
1512         clean_writequeues();
1513
1514         foreach_conn(free_conn);
1515
1516         mutex_unlock(&connections_lock);
1517         kmem_cache_destroy(con_cache);
1518 }
1519
1520 int dlm_lowcomms_start(void)
1521 {
1522         int error = -EINVAL;
1523         struct connection *con;
1524         int i;
1525
1526         for (i = 0; i < CONN_HASH_SIZE; i++)
1527                 INIT_HLIST_HEAD(&connection_hash[i]);
1528
1529         init_local();
1530         if (!dlm_local_count) {
1531                 error = -ENOTCONN;
1532                 log_print("no local IP address has been set");
1533                 goto out;
1534         }
1535
1536         error = -ENOMEM;
1537         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1538                                       __alignof__(struct connection), 0,
1539                                       NULL);
1540         if (!con_cache)
1541                 goto out;
1542
1543         /* Start listening */
1544         if (dlm_config.ci_protocol == 0)
1545                 error = tcp_listen_for_all();
1546         else
1547                 error = sctp_listen_for_all();
1548         if (error)
1549                 goto fail_unlisten;
1550
1551         error = work_start();
1552         if (error)
1553                 goto fail_unlisten;
1554
1555         return 0;
1556
1557 fail_unlisten:
1558         con = nodeid2con(0,0);
1559         if (con) {
1560                 close_connection(con, false);
1561                 kmem_cache_free(con_cache, con);
1562         }
1563         kmem_cache_destroy(con_cache);
1564
1565 out:
1566         return error;
1567 }