New training

Linux graphics course

New training

Linux graphics course

Bootlin logo

Elixir Cross Referencer

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2009 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

/*
 * lowcomms.c
 *
 * This is the "low-level" comms layer.
 *
 * It is responsible for sending/receiving messages
 * from other nodes in the cluster.
 *
 * Cluster nodes are referred to by their nodeids. nodeids are
 * simply 32 bit numbers to the locking module - if they need to
 * be expanded for the cluster infrastructure then that is its
 * responsibility. It is this layer's
 * responsibility to resolve these into IP address or
 * whatever it needs for inter-node communication.
 *
 * The comms level is two kernel threads that deal mainly with
 * the receiving of messages from other nodes and passing them
 * up to the mid-level comms layer (which understands the
 * message format) for execution by the locking core, and
 * a send thread which does all the setting up of connections
 * to remote nodes and the sending of data. Threads are not allowed
 * to send their own data because it may cause them to wait in times
 * of high load. Also, this way, the sending thread can collect together
 * messages bound for one node and send them in one block.
 *
 * lowcomms will choose to use either TCP or SCTP as its transport layer
 * depending on the configuration variable 'protocol'. This should be set
 * to 0 (default) for TCP or 1 for SCTP. It should be configured using a
 * cluster-wide mechanism as it must be the same on all nodes of the cluster
 * for the DLM to function.
 *
 */

#include <asm/ioctls.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mutex.h>
#include <linux/sctp.h>
#include <linux/slab.h>
#include <net/sctp/sctp.h>
#include <net/ipv6.h>

#include "dlm_internal.h"
#include "lowcomms.h"
#include "midcomms.h"
#include "config.h"

#define NEEDED_RMEM (4*1024*1024)
#define CONN_HASH_SIZE 32

/* Number of messages to send before rescheduling */
#define MAX_SEND_MSG_COUNT 25

struct cbuf {
	unsigned int base;
	unsigned int len;
	unsigned int mask;
};

static void cbuf_add(struct cbuf *cb, int n)
{
	cb->len += n;
}

static int cbuf_data(struct cbuf *cb)
{
	return ((cb->base + cb->len) & cb->mask);
}

static void cbuf_init(struct cbuf *cb, int size)
{
	cb->base = cb->len = 0;
	cb->mask = size-1;
}

static void cbuf_eat(struct cbuf *cb, int n)
{
	cb->len  -= n;
	cb->base += n;
	cb->base &= cb->mask;
}

static bool cbuf_empty(struct cbuf *cb)
{
	return cb->len == 0;
}

struct connection {
	struct socket *sock;	/* NULL if not connected */
	uint32_t nodeid;	/* So we know who we are in the list */
	struct mutex sock_mutex;
	unsigned long flags;
#define CF_READ_PENDING 1
#define CF_WRITE_PENDING 2
#define CF_CONNECT_PENDING 3
#define CF_INIT_PENDING 4
#define CF_IS_OTHERCON 5
#define CF_CLOSE 6
#define CF_APP_LIMITED 7
	struct list_head writequeue;  /* List of outgoing writequeue_entries */
	spinlock_t writequeue_lock;
	int (*rx_action) (struct connection *);	/* What to do when active */
	void (*connect_action) (struct connection *);	/* What to do to connect */
	struct page *rx_page;
	struct cbuf cb;
	int retries;
#define MAX_CONNECT_RETRIES 3
	struct hlist_node list;
	struct connection *othercon;
	struct work_struct rwork; /* Receive workqueue */
	struct work_struct swork; /* Send workqueue */
	void (*orig_error_report)(struct sock *);
	void (*orig_data_ready)(struct sock *);
	void (*orig_state_change)(struct sock *);
	void (*orig_write_space)(struct sock *);
};
#define sock2con(x) ((struct connection *)(x)->sk_user_data)

/* An entry waiting to be sent */
struct writequeue_entry {
	struct list_head list;
	struct page *page;
	int offset;
	int len;
	int end;
	int users;
	struct connection *con;
};

struct dlm_node_addr {
	struct list_head list;
	int nodeid;
	int addr_count;
	int curr_addr_index;
	struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
};

static LIST_HEAD(dlm_node_addrs);
static DEFINE_SPINLOCK(dlm_node_addrs_spin);

static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
static int dlm_local_count;
static int dlm_allow_conn;

/* Work queues */
static struct workqueue_struct *recv_workqueue;
static struct workqueue_struct *send_workqueue;

static struct hlist_head connection_hash[CONN_HASH_SIZE];
static DEFINE_MUTEX(connections_lock);
static struct kmem_cache *con_cache;

static void process_recv_sockets(struct work_struct *work);
static void process_send_sockets(struct work_struct *work);


/* This is deliberately very simple because most clusters have simple
   sequential nodeids, so we should be able to go straight to a connection
   struct in the array */
static inline int nodeid_hash(int nodeid)
{
	return nodeid & (CONN_HASH_SIZE-1);
}

static struct connection *__find_con(int nodeid)
{
	int r;
	struct connection *con;

	r = nodeid_hash(nodeid);

	hlist_for_each_entry(con, &connection_hash[r], list) {
		if (con->nodeid == nodeid)
			return con;
	}
	return NULL;
}

/*
 * If 'allocation' is zero then we don't attempt to create a new
 * connection structure for this node.
 */
static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
{
	struct connection *con = NULL;
	int r;

	con = __find_con(nodeid);
	if (con || !alloc)
		return con;

	con = kmem_cache_zalloc(con_cache, alloc);
	if (!con)
		return NULL;

	r = nodeid_hash(nodeid);
	hlist_add_head(&con->list, &connection_hash[r]);

	con->nodeid = nodeid;
	mutex_init(&con->sock_mutex);
	INIT_LIST_HEAD(&con->writequeue);
	spin_lock_init(&con->writequeue_lock);
	INIT_WORK(&con->swork, process_send_sockets);
	INIT_WORK(&con->rwork, process_recv_sockets);

	/* Setup action pointers for child sockets */
	if (con->nodeid) {
		struct connection *zerocon = __find_con(0);

		con->connect_action = zerocon->connect_action;
		if (!con->rx_action)
			con->rx_action = zerocon->rx_action;
	}

	return con;
}

/* Loop round all connections */
static void foreach_conn(void (*conn_func)(struct connection *c))
{
	int i;
	struct hlist_node *n;
	struct connection *con;

	for (i = 0; i < CONN_HASH_SIZE; i++) {
		hlist_for_each_entry_safe(con, n, &connection_hash[i], list)
			conn_func(con);
	}
}

static struct connection *nodeid2con(int nodeid, gfp_t allocation)
{
	struct connection *con;

	mutex_lock(&connections_lock);
	con = __nodeid2con(nodeid, allocation);
	mutex_unlock(&connections_lock);

	return con;
}

static struct dlm_node_addr *find_node_addr(int nodeid)
{
	struct dlm_node_addr *na;

	list_for_each_entry(na, &dlm_node_addrs, list) {
		if (na->nodeid == nodeid)
			return na;
	}
	return NULL;
}

static int addr_compare(struct sockaddr_storage *x, struct sockaddr_storage *y)
{
	switch (x->ss_family) {
	case AF_INET: {
		struct sockaddr_in *sinx = (struct sockaddr_in *)x;
		struct sockaddr_in *siny = (struct sockaddr_in *)y;
		if (sinx->sin_addr.s_addr != siny->sin_addr.s_addr)
			return 0;
		if (sinx->sin_port != siny->sin_port)
			return 0;
		break;
	}
	case AF_INET6: {
		struct sockaddr_in6 *sinx = (struct sockaddr_in6 *)x;
		struct sockaddr_in6 *siny = (struct sockaddr_in6 *)y;
		if (!ipv6_addr_equal(&sinx->sin6_addr, &siny->sin6_addr))
			return 0;
		if (sinx->sin6_port != siny->sin6_port)
			return 0;
		break;
	}
	default:
		return 0;
	}
	return 1;
}

static int nodeid_to_addr(int nodeid, struct sockaddr_storage *sas_out,
			  struct sockaddr *sa_out, bool try_new_addr)
{
	struct sockaddr_storage sas;
	struct dlm_node_addr *na;

	if (!dlm_local_count)
		return -1;

	spin_lock(&dlm_node_addrs_spin);
	na = find_node_addr(nodeid);
	if (na && na->addr_count) {
		memcpy(&sas, na->addr[na->curr_addr_index],
		       sizeof(struct sockaddr_storage));

		if (try_new_addr) {
			na->curr_addr_index++;
			if (na->curr_addr_index == na->addr_count)
				na->curr_addr_index = 0;
		}
	}
	spin_unlock(&dlm_node_addrs_spin);

	if (!na)
		return -EEXIST;

	if (!na->addr_count)
		return -ENOENT;

	if (sas_out)
		memcpy(sas_out, &sas, sizeof(struct sockaddr_storage));

	if (!sa_out)
		return 0;

	if (dlm_local_addr[0]->ss_family == AF_INET) {
		struct sockaddr_in *in4  = (struct sockaddr_in *) &sas;
		struct sockaddr_in *ret4 = (struct sockaddr_in *) sa_out;
		ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
	} else {
		struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &sas;
		struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) sa_out;
		ret6->sin6_addr = in6->sin6_addr;
	}

	return 0;
}

static int addr_to_nodeid(struct sockaddr_storage *addr, int *nodeid)
{
	struct dlm_node_addr *na;
	int rv = -EEXIST;
	int addr_i;

	spin_lock(&dlm_node_addrs_spin);
	list_for_each_entry(na, &dlm_node_addrs, list) {
		if (!na->addr_count)
			continue;

		for (addr_i = 0; addr_i < na->addr_count; addr_i++) {
			if (addr_compare(na->addr[addr_i], addr)) {
				*nodeid = na->nodeid;
				rv = 0;
				goto unlock;
			}
		}
	}
unlock:
	spin_unlock(&dlm_node_addrs_spin);
	return rv;
}

int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
{
	struct sockaddr_storage *new_addr;
	struct dlm_node_addr *new_node, *na;

	new_node = kzalloc(sizeof(struct dlm_node_addr), GFP_NOFS);
	if (!new_node)
		return -ENOMEM;

	new_addr = kzalloc(sizeof(struct sockaddr_storage), GFP_NOFS);
	if (!new_addr) {
		kfree(new_node);
		return -ENOMEM;
	}

	memcpy(new_addr, addr, len);

	spin_lock(&dlm_node_addrs_spin);
	na = find_node_addr(nodeid);
	if (!na) {
		new_node->nodeid = nodeid;
		new_node->addr[0] = new_addr;
		new_node->addr_count = 1;
		list_add(&new_node->list, &dlm_node_addrs);
		spin_unlock(&dlm_node_addrs_spin);
		return 0;
	}

	if (na->addr_count >= DLM_MAX_ADDR_COUNT) {
		spin_unlock(&dlm_node_addrs_spin);
		kfree(new_addr);
		kfree(new_node);
		return -ENOSPC;
	}

	na->addr[na->addr_count++] = new_addr;
	spin_unlock(&dlm_node_addrs_spin);
	kfree(new_node);
	return 0;
}

/* Data available on socket or listen socket received a connect */
static void lowcomms_data_ready(struct sock *sk)
{
	struct connection *con = sock2con(sk);
	if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
		queue_work(recv_workqueue, &con->rwork);
}

static void lowcomms_write_space(struct sock *sk)
{
	struct connection *con = sock2con(sk);

	if (!con)
		return;

	clear_bit(SOCK_NOSPACE, &con->sock->flags);

	if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
		con->sock->sk->sk_write_pending--;
		clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags);
	}

	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
		queue_work(send_workqueue, &con->swork);
}

static inline void lowcomms_connect_sock(struct connection *con)
{
	if (test_bit(CF_CLOSE, &con->flags))
		return;
	if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
		queue_work(send_workqueue, &con->swork);
}

static void lowcomms_state_change(struct sock *sk)
{
	/* SCTP layer is not calling sk_data_ready when the connection
	 * is done, so we catch the signal through here. Also, it
	 * doesn't switch socket state when entering shutdown, so we
	 * skip the write in that case.
	 */
	if (sk->sk_shutdown) {
		if (sk->sk_shutdown == RCV_SHUTDOWN)
			lowcomms_data_ready(sk);
	} else if (sk->sk_state == TCP_ESTABLISHED) {
		lowcomms_write_space(sk);
	}
}

int dlm_lowcomms_connect_node(int nodeid)
{
	struct connection *con;

	if (nodeid == dlm_our_nodeid())
		return 0;

	con = nodeid2con(nodeid, GFP_NOFS);
	if (!con)
		return -ENOMEM;
	lowcomms_connect_sock(con);
	return 0;
}

static void lowcomms_error_report(struct sock *sk)
{
	struct connection *con;
	struct sockaddr_storage saddr;
	int buflen;
	void (*orig_report)(struct sock *) = NULL;

	read_lock_bh(&sk->sk_callback_lock);
	con = sock2con(sk);
	if (con == NULL)
		goto out;

	orig_report = con->orig_error_report;
	if (con->sock == NULL ||
	    kernel_getpeername(con->sock, (struct sockaddr *)&saddr, &buflen)) {
		printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
				   "sending to node %d, port %d, "
				   "sk_err=%d/%d\n", dlm_our_nodeid(),
				   con->nodeid, dlm_config.ci_tcp_port,
				   sk->sk_err, sk->sk_err_soft);
	} else if (saddr.ss_family == AF_INET) {
		struct sockaddr_in *sin4 = (struct sockaddr_in *)&saddr;

		printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
				   "sending to node %d at %pI4, port %d, "
				   "sk_err=%d/%d\n", dlm_our_nodeid(),
				   con->nodeid, &sin4->sin_addr.s_addr,
				   dlm_config.ci_tcp_port, sk->sk_err,
				   sk->sk_err_soft);
	} else {
		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&saddr;

		printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
				   "sending to node %d at %u.%u.%u.%u, "
				   "port %d, sk_err=%d/%d\n", dlm_our_nodeid(),
				   con->nodeid, sin6->sin6_addr.s6_addr32[0],
				   sin6->sin6_addr.s6_addr32[1],
				   sin6->sin6_addr.s6_addr32[2],
				   sin6->sin6_addr.s6_addr32[3],
				   dlm_config.ci_tcp_port, sk->sk_err,
				   sk->sk_err_soft);
	}
out:
	read_unlock_bh(&sk->sk_callback_lock);
	if (orig_report)
		orig_report(sk);
}

/* Note: sk_callback_lock must be locked before calling this function. */
static void save_callbacks(struct connection *con, struct sock *sk)
{
	lock_sock(sk);
	con->orig_data_ready = sk->sk_data_ready;
	con->orig_state_change = sk->sk_state_change;
	con->orig_write_space = sk->sk_write_space;
	con->orig_error_report = sk->sk_error_report;
	release_sock(sk);
}

static void restore_callbacks(struct connection *con, struct sock *sk)
{
	write_lock_bh(&sk->sk_callback_lock);
	lock_sock(sk);
	sk->sk_user_data = NULL;
	sk->sk_data_ready = con->orig_data_ready;
	sk->sk_state_change = con->orig_state_change;
	sk->sk_write_space = con->orig_write_space;
	sk->sk_error_report = con->orig_error_report;
	release_sock(sk);
	write_unlock_bh(&sk->sk_callback_lock);
}

/* Make a socket active */
static void add_sock(struct socket *sock, struct connection *con)
{
	struct sock *sk = sock->sk;

	write_lock_bh(&sk->sk_callback_lock);
	con->sock = sock;

	sk->sk_user_data = con;
	if (!test_bit(CF_IS_OTHERCON, &con->flags))
		save_callbacks(con, sk);
	/* Install a data_ready callback */
	sk->sk_data_ready = lowcomms_data_ready;
	sk->sk_write_space = lowcomms_write_space;
	sk->sk_state_change = lowcomms_state_change;
	sk->sk_allocation = GFP_NOFS;
	sk->sk_error_report = lowcomms_error_report;
	write_unlock_bh(&sk->sk_callback_lock);
}

/* Add the port number to an IPv6 or 4 sockaddr and return the address
   length */
static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
			  int *addr_len)
{
	saddr->ss_family =  dlm_local_addr[0]->ss_family;
	if (saddr->ss_family == AF_INET) {
		struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
		in4_addr->sin_port = cpu_to_be16(port);
		*addr_len = sizeof(struct sockaddr_in);
		memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
	} else {
		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
		in6_addr->sin6_port = cpu_to_be16(port);
		*addr_len = sizeof(struct sockaddr_in6);
	}
	memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
}

/* Close a remote connection and tidy up */
static void close_connection(struct connection *con, bool and_other,
			     bool tx, bool rx)
{
	clear_bit(CF_CONNECT_PENDING, &con->flags);
	clear_bit(CF_WRITE_PENDING, &con->flags);
	if (tx && cancel_work_sync(&con->swork))
		log_print("canceled swork for node %d", con->nodeid);
	if (rx && cancel_work_sync(&con->rwork))
		log_print("canceled rwork for node %d", con->nodeid);

	mutex_lock(&con->sock_mutex);
	if (con->sock) {
		if (!test_bit(CF_IS_OTHERCON, &con->flags))
			restore_callbacks(con, con->sock->sk);
		sock_release(con->sock);
		con->sock = NULL;
	}
	if (con->othercon && and_other) {
		/* Will only re-enter once. */
		close_connection(con->othercon, false, true, true);
	}
	if (con->rx_page) {
		__free_page(con->rx_page);
		con->rx_page = NULL;
	}

	con->retries = 0;
	mutex_unlock(&con->sock_mutex);
}

/* Data received from remote end */
static int receive_from_sock(struct connection *con)
{
	int ret = 0;
	struct msghdr msg = {};
	struct kvec iov[2];
	unsigned len;
	int r;
	int call_again_soon = 0;
	int nvec;

	mutex_lock(&con->sock_mutex);

	if (con->sock == NULL) {
		ret = -EAGAIN;
		goto out_close;
	}
	if (con->nodeid == 0) {
		ret = -EINVAL;
		goto out_close;
	}

	if (con->rx_page == NULL) {
		/*
		 * This doesn't need to be atomic, but I think it should
		 * improve performance if it is.
		 */
		con->rx_page = alloc_page(GFP_ATOMIC);
		if (con->rx_page == NULL)
			goto out_resched;
		cbuf_init(&con->cb, PAGE_SIZE);
	}

	/*
	 * iov[0] is the bit of the circular buffer between the current end
	 * point (cb.base + cb.len) and the end of the buffer.
	 */
	iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
	iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
	iov[1].iov_len = 0;
	nvec = 1;

	/*
	 * iov[1] is the bit of the circular buffer between the start of the
	 * buffer and the start of the currently used section (cb.base)
	 */
	if (cbuf_data(&con->cb) >= con->cb.base) {
		iov[0].iov_len = PAGE_SIZE - cbuf_data(&con->cb);
		iov[1].iov_len = con->cb.base;
		iov[1].iov_base = page_address(con->rx_page);
		nvec = 2;
	}
	len = iov[0].iov_len + iov[1].iov_len;

	r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
			       MSG_DONTWAIT | MSG_NOSIGNAL);
	if (ret <= 0)
		goto out_close;
	else if (ret == len)
		call_again_soon = 1;

	cbuf_add(&con->cb, ret);
	ret = dlm_process_incoming_buffer(con->nodeid,
					  page_address(con->rx_page),
					  con->cb.base, con->cb.len,
					  PAGE_SIZE);
	if (ret == -EBADMSG) {
		log_print("lowcomms: addr=%p, base=%u, len=%u, read=%d",
			  page_address(con->rx_page), con->cb.base,
			  con->cb.len, r);
	}
	if (ret < 0)
		goto out_close;
	cbuf_eat(&con->cb, ret);

	if (cbuf_empty(&con->cb) && !call_again_soon) {
		__free_page(con->rx_page);
		con->rx_page = NULL;
	}

	if (call_again_soon)
		goto out_resched;
	mutex_unlock(&con->sock_mutex);
	return 0;

out_resched:
	if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
		queue_work(recv_workqueue, &con->rwork);
	mutex_unlock(&con->sock_mutex);
	return -EAGAIN;

out_close:
	mutex_unlock(&con->sock_mutex);
	if (ret != -EAGAIN) {
		close_connection(con, false, true, false);
		/* Reconnect when there is something to send */
	}
	/* Don't return success if we really got EOF */
	if (ret == 0)
		ret = -EAGAIN;

	return ret;
}

/* Listening socket is busy, accept a connection */
static int tcp_accept_from_sock(struct connection *con)
{
	int result;
	struct sockaddr_storage peeraddr;
	struct socket *newsock;
	int len;
	int nodeid;
	struct connection *newcon;
	struct connection *addcon;

	mutex_lock(&connections_lock);
	if (!dlm_allow_conn) {
		mutex_unlock(&connections_lock);
		return -1;
	}
	mutex_unlock(&connections_lock);

	memset(&peeraddr, 0, sizeof(peeraddr));
	result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
				  SOCK_STREAM, IPPROTO_TCP, &newsock);
	if (result < 0)
		return -ENOMEM;

	mutex_lock_nested(&con->sock_mutex, 0);

	result = -ENOTCONN;
	if (con->sock == NULL)
		goto accept_err;

	newsock->type = con->sock->type;
	newsock->ops = con->sock->ops;

	result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
	if (result < 0)
		goto accept_err;

	/* Get the connected socket's peer */
	memset(&peeraddr, 0, sizeof(peeraddr));
	if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
				  &len, 2)) {
		result = -ECONNABORTED;
		goto accept_err;
	}

	/* Get the new node's NODEID */
	make_sockaddr(&peeraddr, 0, &len);
	if (addr_to_nodeid(&peeraddr, &nodeid)) {
		unsigned char *b=(unsigned char *)&peeraddr;
		log_print("connect from non cluster node");
		print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE, 
				     b, sizeof(struct sockaddr_storage));
		sock_release(newsock);
		mutex_unlock(&con->sock_mutex);
		return -1;
	}

	log_print("got connection from %d", nodeid);

	/*  Check to see if we already have a connection to this node. This
	 *  could happen if the two nodes initiate a connection at roughly
	 *  the same time and the connections cross on the wire.
	 *  In this case we store the incoming one in "othercon"
	 */
	newcon = nodeid2con(nodeid, GFP_NOFS);
	if (!newcon) {
		result = -ENOMEM;
		goto accept_err;
	}
	mutex_lock_nested(&newcon->sock_mutex, 1);
	if (newcon->sock) {
		struct connection *othercon = newcon->othercon;

		if (!othercon) {
			othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
			if (!othercon) {
				log_print("failed to allocate incoming socket");
				mutex_unlock(&newcon->sock_mutex);
				result = -ENOMEM;
				goto accept_err;
			}
			othercon->nodeid = nodeid;
			othercon->rx_action = receive_from_sock;
			mutex_init(&othercon->sock_mutex);
			INIT_WORK(&othercon->swork, process_send_sockets);
			INIT_WORK(&othercon->rwork, process_recv_sockets);
			set_bit(CF_IS_OTHERCON, &othercon->flags);
		}
		if (!othercon->sock) {
			newcon->othercon = othercon;
			othercon->sock = newsock;
			newsock->sk->sk_user_data = othercon;
			add_sock(newsock, othercon);
			addcon = othercon;
		}
		else {
			printk("Extra connection from node %d attempted\n", nodeid);
			result = -EAGAIN;
			mutex_unlock(&newcon->sock_mutex);
			goto accept_err;
		}
	}
	else {
		newsock->sk->sk_user_data = newcon;
		newcon->rx_action = receive_from_sock;
		add_sock(newsock, newcon);
		addcon = newcon;
	}

	mutex_unlock(&newcon->sock_mutex);

	/*
	 * Add it to the active queue in case we got data
	 * between processing the accept adding the socket
	 * to the read_sockets list
	 */
	if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
		queue_work(recv_workqueue, &addcon->rwork);
	mutex_unlock(&con->sock_mutex);

	return 0;

accept_err:
	mutex_unlock(&con->sock_mutex);
	sock_release(newsock);

	if (result != -EAGAIN)
		log_print("error accepting connection from node: %d", result);
	return result;
}

static int sctp_accept_from_sock(struct connection *con)
{
	/* Check that the new node is in the lockspace */
	struct sctp_prim prim;
	int nodeid;
	int prim_len, ret;
	int addr_len;
	struct connection *newcon;
	struct connection *addcon;
	struct socket *newsock;

	mutex_lock(&connections_lock);
	if (!dlm_allow_conn) {
		mutex_unlock(&connections_lock);
		return -1;
	}
	mutex_unlock(&connections_lock);

	mutex_lock_nested(&con->sock_mutex, 0);

	ret = kernel_accept(con->sock, &newsock, O_NONBLOCK);
	if (ret < 0)
		goto accept_err;

	memset(&prim, 0, sizeof(struct sctp_prim));
	prim_len = sizeof(struct sctp_prim);

	ret = kernel_getsockopt(newsock, IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
				(char *)&prim, &prim_len);
	if (ret < 0) {
		log_print("getsockopt/sctp_primary_addr failed: %d", ret);
		goto accept_err;
	}

	make_sockaddr(&prim.ssp_addr, 0, &addr_len);
	if (addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
		unsigned char *b = (unsigned char *)&prim.ssp_addr;

		log_print("reject connect from unknown addr");
		print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE,
				     b, sizeof(struct sockaddr_storage));
		goto accept_err;
	}

	newcon = nodeid2con(nodeid, GFP_NOFS);
	if (!newcon) {
		ret = -ENOMEM;
		goto accept_err;
	}

	mutex_lock_nested(&newcon->sock_mutex, 1);

	if (newcon->sock) {
		struct connection *othercon = newcon->othercon;

		if (!othercon) {
			othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
			if (!othercon) {
				log_print("failed to allocate incoming socket");
				mutex_unlock(&newcon->sock_mutex);
				ret = -ENOMEM;
				goto accept_err;
			}
			othercon->nodeid = nodeid;
			othercon->rx_action = receive_from_sock;
			mutex_init(&othercon->sock_mutex);
			INIT_WORK(&othercon->swork, process_send_sockets);
			INIT_WORK(&othercon->rwork, process_recv_sockets);
			set_bit(CF_IS_OTHERCON, &othercon->flags);
		}
		if (!othercon->sock) {
			newcon->othercon = othercon;
			othercon->sock = newsock;
			newsock->sk->sk_user_data = othercon;
			add_sock(newsock, othercon);
			addcon = othercon;
		} else {
			printk("Extra connection from node %d attempted\n", nodeid);
			ret = -EAGAIN;
			mutex_unlock(&newcon->sock_mutex);
			goto accept_err;
		}
	} else {
		newsock->sk->sk_user_data = newcon;
		newcon->rx_action = receive_from_sock;
		add_sock(newsock, newcon);
		addcon = newcon;
	}

	log_print("connected to %d", nodeid);

	mutex_unlock(&newcon->sock_mutex);

	/*
	 * Add it to the active queue in case we got data
	 * between processing the accept adding the socket
	 * to the read_sockets list
	 */
	if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
		queue_work(recv_workqueue, &addcon->rwork);
	mutex_unlock(&con->sock_mutex);

	return 0;

accept_err:
	mutex_unlock(&con->sock_mutex);
	if (newsock)
		sock_release(newsock);
	if (ret != -EAGAIN)
		log_print("error accepting connection from node: %d", ret);

	return ret;
}

static void free_entry(struct writequeue_entry *e)
{
	__free_page(e->page);
	kfree(e);
}

/*
 * writequeue_entry_complete - try to delete and free write queue entry
 * @e: write queue entry to try to delete
 * @completed: bytes completed
 *
 * writequeue_lock must be held.
 */
static void writequeue_entry_complete(struct writequeue_entry *e, int completed)
{
	e->offset += completed;
	e->len -= completed;

	if (e->len == 0 && e->users == 0) {
		list_del(&e->list);
		free_entry(e);
	}
}

/*
 * sctp_bind_addrs - bind a SCTP socket to all our addresses
 */
static int sctp_bind_addrs(struct connection *con, uint16_t port)
{
	struct sockaddr_storage localaddr;
	int i, addr_len, result = 0;

	for (i = 0; i < dlm_local_count; i++) {
		memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
		make_sockaddr(&localaddr, port, &addr_len);

		if (!i)
			result = kernel_bind(con->sock,
					     (struct sockaddr *)&localaddr,
					     addr_len);
		else
			result = kernel_setsockopt(con->sock, SOL_SCTP,
						   SCTP_SOCKOPT_BINDX_ADD,
						   (char *)&localaddr, addr_len);

		if (result < 0) {
			log_print("Can't bind to %d addr number %d, %d.\n",
				  port, i + 1, result);
			break;
		}
	}
	return result;
}

/* Initiate an SCTP association.
   This is a special case of send_to_sock() in that we don't yet have a
   peeled-off socket for this association, so we use the listening socket
   and add the primary IP address of the remote node.
 */
static void sctp_connect_to_sock(struct connection *con)
{
	struct sockaddr_storage daddr;
	int one = 1;
	int result;
	int addr_len;
	struct socket *sock;

	if (con->nodeid == 0) {
		log_print("attempt to connect sock 0 foiled");
		return;
	}

	mutex_lock(&con->sock_mutex);

	/* Some odd races can cause double-connects, ignore them */
	if (con->retries++ > MAX_CONNECT_RETRIES)
		goto out;

	if (con->sock) {
		log_print("node %d already connected.", con->nodeid);
		goto out;
	}

	memset(&daddr, 0, sizeof(daddr));
	result = nodeid_to_addr(con->nodeid, &daddr, NULL, true);
	if (result < 0) {
		log_print("no address for nodeid %d", con->nodeid);
		goto out;
	}

	/* Create a socket to communicate with */
	result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
				  SOCK_STREAM, IPPROTO_SCTP, &sock);
	if (result < 0)
		goto socket_err;

	sock->sk->sk_user_data = con;
	con->rx_action = receive_from_sock;
	con->connect_action = sctp_connect_to_sock;
	add_sock(sock, con);

	/* Bind to all addresses. */
	if (sctp_bind_addrs(con, 0))
		goto bind_err;

	make_sockaddr(&daddr, dlm_config.ci_tcp_port, &addr_len);

	log_print("connecting to %d", con->nodeid);

	/* Turn off Nagle's algorithm */
	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
			  sizeof(one));

	result = sock->ops->connect(sock, (struct sockaddr *)&daddr, addr_len,
				   O_NONBLOCK);
	if (result == -EINPROGRESS)
		result = 0;
	if (result == 0)
		goto out;


bind_err:
	con->sock = NULL;
	sock_release(sock);

socket_err:
	/*
	 * Some errors are fatal and this list might need adjusting. For other
	 * errors we try again until the max number of retries is reached.
	 */
	if (result != -EHOSTUNREACH &&
	    result != -ENETUNREACH &&
	    result != -ENETDOWN &&
	    result != -EINVAL &&
	    result != -EPROTONOSUPPORT) {
		log_print("connect %d try %d error %d", con->nodeid,
			  con->retries, result);
		mutex_unlock(&con->sock_mutex);
		msleep(1000);
		clear_bit(CF_CONNECT_PENDING, &con->flags);
		lowcomms_connect_sock(con);
		return;
	}

out:
	mutex_unlock(&con->sock_mutex);
	set_bit(CF_WRITE_PENDING, &con->flags);
}

/* Connect a new socket to its peer */
static void tcp_connect_to_sock(struct connection *con)
{
	struct sockaddr_storage saddr, src_addr;
	int addr_len;
	struct socket *sock = NULL;
	int one = 1;
	int result;

	if (con->nodeid == 0) {
		log_print("attempt to connect sock 0 foiled");
		return;
	}

	mutex_lock(&con->sock_mutex);
	if (con->retries++ > MAX_CONNECT_RETRIES)
		goto out;

	/* Some odd races can cause double-connects, ignore them */
	if (con->sock)
		goto out;

	/* Create a socket to communicate with */
	result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
				  SOCK_STREAM, IPPROTO_TCP, &sock);
	if (result < 0)
		goto out_err;

	memset(&saddr, 0, sizeof(saddr));
	result = nodeid_to_addr(con->nodeid, &saddr, NULL, false);
	if (result < 0) {
		log_print("no address for nodeid %d", con->nodeid);
		goto out_err;
	}

	sock->sk->sk_user_data = con;
	con->rx_action = receive_from_sock;
	con->connect_action = tcp_connect_to_sock;
	add_sock(sock, con);

	/* Bind to our cluster-known address connecting to avoid
	   routing problems */
	memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
	make_sockaddr(&src_addr, 0, &addr_len);
	result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
				 addr_len);
	if (result < 0) {
		log_print("could not bind for connect: %d", result);
		/* This *may* not indicate a critical error */
	}

	make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);

	log_print("connecting to %d", con->nodeid);

	/* Turn off Nagle's algorithm */
	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
			  sizeof(one));

	result = sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
				   O_NONBLOCK);
	if (result == -EINPROGRESS)
		result = 0;
	if (result == 0)
		goto out;

out_err:
	if (con->sock) {
		sock_release(con->sock);
		con->sock = NULL;
	} else if (sock) {
		sock_release(sock);
	}
	/*
	 * Some errors are fatal and this list might need adjusting. For other
	 * errors we try again until the max number of retries is reached.
	 */
	if (result != -EHOSTUNREACH &&
	    result != -ENETUNREACH &&
	    result != -ENETDOWN && 
	    result != -EINVAL &&
	    result != -EPROTONOSUPPORT) {
		log_print("connect %d try %d error %d", con->nodeid,
			  con->retries, result);
		mutex_unlock(&con->sock_mutex);
		msleep(1000);
		clear_bit(CF_CONNECT_PENDING, &con->flags);
		lowcomms_connect_sock(con);
		return;
	}
out:
	mutex_unlock(&con->sock_mutex);
	set_bit(CF_WRITE_PENDING, &con->flags);
	return;
}

static struct socket *tcp_create_listen_sock(struct connection *con,
					     struct sockaddr_storage *saddr)
{
	struct socket *sock = NULL;
	int result = 0;
	int one = 1;
	int addr_len;

	if (dlm_local_addr[0]->ss_family == AF_INET)
		addr_len = sizeof(struct sockaddr_in);
	else
		addr_len = sizeof(struct sockaddr_in6);

	/* Create a socket to communicate with */
	result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
				  SOCK_STREAM, IPPROTO_TCP, &sock);
	if (result < 0) {
		log_print("Can't create listening comms socket");
		goto create_out;
	}

	/* Turn off Nagle's algorithm */
	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
			  sizeof(one));

	result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
				   (char *)&one, sizeof(one));

	if (result < 0) {
		log_print("Failed to set SO_REUSEADDR on socket: %d", result);
	}
	sock->sk->sk_user_data = con;

	con->rx_action = tcp_accept_from_sock;
	con->connect_action = tcp_connect_to_sock;

	/* Bind to our port */
	make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
	result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
	if (result < 0) {
		log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
		sock_release(sock);
		sock = NULL;
		con->sock = NULL;
		goto create_out;
	}
	result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
				 (char *)&one, sizeof(one));
	if (result < 0) {
		log_print("Set keepalive failed: %d", result);
	}

	result = sock->ops->listen(sock, 5);
	if (result < 0) {
		log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
		sock_release(sock);
		sock = NULL;
		goto create_out;
	}

create_out:
	return sock;
}

/* Get local addresses */
static void init_local(void)
{
	struct sockaddr_storage sas, *addr;
	int i;

	dlm_local_count = 0;
	for (i = 0; i < DLM_MAX_ADDR_COUNT; i++) {
		if (dlm_our_addr(&sas, i))
			break;

		addr = kmemdup(&sas, sizeof(*addr), GFP_NOFS);
		if (!addr)
			break;
		dlm_local_addr[dlm_local_count++] = addr;
	}
}

/* Initialise SCTP socket and bind to all interfaces */
static int sctp_listen_for_all(void)
{
	struct socket *sock = NULL;
	int result = -EINVAL;
	struct connection *con = nodeid2con(0, GFP_NOFS);
	int bufsize = NEEDED_RMEM;
	int one = 1;

	if (!con)
		return -ENOMEM;

	log_print("Using SCTP for communications");

	result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
				  SOCK_STREAM, IPPROTO_SCTP, &sock);
	if (result < 0) {
		log_print("Can't create comms socket, check SCTP is loaded");
		goto out;
	}

	result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
				 (char *)&bufsize, sizeof(bufsize));
	if (result)
		log_print("Error increasing buffer space on socket %d", result);

	result = kernel_setsockopt(sock, SOL_SCTP, SCTP_NODELAY, (char *)&one,
				   sizeof(one));
	if (result < 0)
		log_print("Could not set SCTP NODELAY error %d\n", result);

	write_lock_bh(&sock->sk->sk_callback_lock);
	/* Init con struct */
	sock->sk->sk_user_data = con;
	con->sock = sock;
	con->sock->sk->sk_data_ready = lowcomms_data_ready;
	con->rx_action = sctp_accept_from_sock;
	con->connect_action = sctp_connect_to_sock;

	write_unlock_bh(&sock->sk->sk_callback_lock);

	/* Bind to all addresses. */
	if (sctp_bind_addrs(con, dlm_config.ci_tcp_port))
		goto create_delsock;

	result = sock->ops->listen(sock, 5);
	if (result < 0) {
		log_print("Can't set socket listening");
		goto create_delsock;
	}

	return 0;

create_delsock:
	sock_release(sock);
	con->sock = NULL;
out:
	return result;
}

static int tcp_listen_for_all(void)
{
	struct socket *sock = NULL;
	struct connection *con = nodeid2con(0, GFP_NOFS);
	int result = -EINVAL;

	if (!con)
		return -ENOMEM;

	/* We don't support multi-homed hosts */
	if (dlm_local_addr[1] != NULL) {
		log_print("TCP protocol can't handle multi-homed hosts, "
			  "try SCTP");
		return -EINVAL;
	}

	log_print("Using TCP for communications");

	sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
	if (sock) {
		add_sock(sock, con);
		result = 0;
	}
	else {
		result = -EADDRINUSE;
	}

	return result;
}



static struct writequeue_entry *new_writequeue_entry(struct connection *con,
						     gfp_t allocation)
{
	struct writequeue_entry *entry;

	entry = kmalloc(sizeof(struct writequeue_entry), allocation);
	if (!entry)
		return NULL;

	entry->page = alloc_page(allocation);
	if (!entry->page) {
		kfree(entry);
		return NULL;
	}

	entry->offset = 0;
	entry->len = 0;
	entry->end = 0;
	entry->users = 0;
	entry->con = con;

	return entry;
}

void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
{
	struct connection *con;
	struct writequeue_entry *e;
	int offset = 0;

	con = nodeid2con(nodeid, allocation);
	if (!con)
		return NULL;

	spin_lock(&con->writequeue_lock);
	e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
	if ((&e->list == &con->writequeue) ||
	    (PAGE_SIZE - e->end < len)) {
		e = NULL;
	} else {
		offset = e->end;
		e->end += len;
		e->users++;
	}
	spin_unlock(&con->writequeue_lock);

	if (e) {
	got_one:
		*ppc = page_address(e->page) + offset;
		return e;
	}

	e = new_writequeue_entry(con, allocation);
	if (e) {
		spin_lock(&con->writequeue_lock);
		offset = e->end;
		e->end += len;
		e->users++;
		list_add_tail(&e->list, &con->writequeue);
		spin_unlock(&con->writequeue_lock);
		goto got_one;
	}
	return NULL;
}

void dlm_lowcomms_commit_buffer(void *mh)
{
	struct writequeue_entry *e = (struct writequeue_entry *)mh;
	struct connection *con = e->con;
	int users;

	spin_lock(&con->writequeue_lock);
	users = --e->users;
	if (users)
		goto out;
	e->len = e->end - e->offset;
	spin_unlock(&con->writequeue_lock);

	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
		queue_work(send_workqueue, &con->swork);
	}
	return;

out:
	spin_unlock(&con->writequeue_lock);
	return;
}

/* Send a message */
static void send_to_sock(struct connection *con)
{
	int ret = 0;
	const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
	struct writequeue_entry *e;
	int len, offset;
	int count = 0;

	mutex_lock(&con->sock_mutex);
	if (con->sock == NULL)
		goto out_connect;

	spin_lock(&con->writequeue_lock);
	for (;;) {
		e = list_entry(con->writequeue.next, struct writequeue_entry,
			       list);
		if ((struct list_head *) e == &con->writequeue)
			break;

		len = e->len;
		offset = e->offset;
		BUG_ON(len == 0 && e->users == 0);
		spin_unlock(&con->writequeue_lock);

		ret = 0;
		if (len) {
			ret = kernel_sendpage(con->sock, e->page, offset, len,
					      msg_flags);
			if (ret == -EAGAIN || ret == 0) {
				if (ret == -EAGAIN &&
				    test_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags) &&
				    !test_and_set_bit(CF_APP_LIMITED, &con->flags)) {
					/* Notify TCP that we're limited by the
					 * application window size.
					 */
					set_bit(SOCK_NOSPACE, &con->sock->flags);
					con->sock->sk->sk_write_pending++;
				}
				cond_resched();
				goto out;
			} else if (ret < 0)
				goto send_error;
		}

		/* Don't starve people filling buffers */
		if (++count >= MAX_SEND_MSG_COUNT) {
			cond_resched();
			count = 0;
		}

		spin_lock(&con->writequeue_lock);
		writequeue_entry_complete(e, ret);
	}
	spin_unlock(&con->writequeue_lock);
out:
	mutex_unlock(&con->sock_mutex);
	return;

send_error:
	mutex_unlock(&con->sock_mutex);
	close_connection(con, false, false, true);
	lowcomms_connect_sock(con);
	return;

out_connect:
	mutex_unlock(&con->sock_mutex);
	lowcomms_connect_sock(con);
}

static void clean_one_writequeue(struct connection *con)
{
	struct writequeue_entry *e, *safe;

	spin_lock(&con->writequeue_lock);
	list_for_each_entry_safe(e, safe, &con->writequeue, list) {
		list_del(&e->list);
		free_entry(e);
	}
	spin_unlock(&con->writequeue_lock);
}

/* Called from recovery when it knows that a node has
   left the cluster */
int dlm_lowcomms_close(int nodeid)
{
	struct connection *con;
	struct dlm_node_addr *na;

	log_print("closing connection to node %d", nodeid);
	con = nodeid2con(nodeid, 0);
	if (con) {
		set_bit(CF_CLOSE, &con->flags);
		close_connection(con, true, true, true);
		clean_one_writequeue(con);
	}

	spin_lock(&dlm_node_addrs_spin);
	na = find_node_addr(nodeid);
	if (na) {
		list_del(&na->list);
		while (na->addr_count--)
			kfree(na->addr[na->addr_count]);
		kfree(na);
	}
	spin_unlock(&dlm_node_addrs_spin);

	return 0;
}

/* Receive workqueue function */
static void process_recv_sockets(struct work_struct *work)
{
	struct connection *con = container_of(work, struct connection, rwork);
	int err;

	clear_bit(CF_READ_PENDING, &con->flags);
	do {
		err = con->rx_action(con);
	} while (!err);
}

/* Send workqueue function */
static void process_send_sockets(struct work_struct *work)
{
	struct connection *con = container_of(work, struct connection, swork);

	if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags))
		con->connect_action(con);
	if (test_and_clear_bit(CF_WRITE_PENDING, &con->flags))
		send_to_sock(con);
}


/* Discard all entries on the write queues */
static void clean_writequeues(void)
{
	foreach_conn(clean_one_writequeue);
}

static void work_stop(void)
{
	destroy_workqueue(recv_workqueue);
	destroy_workqueue(send_workqueue);
}

static int work_start(void)
{
	recv_workqueue = alloc_workqueue("dlm_recv",
					 WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
	if (!recv_workqueue) {
		log_print("can't start dlm_recv");
		return -ENOMEM;
	}

	send_workqueue = alloc_workqueue("dlm_send",
					 WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
	if (!send_workqueue) {
		log_print("can't start dlm_send");
		destroy_workqueue(recv_workqueue);
		return -ENOMEM;
	}

	return 0;
}

static void stop_conn(struct connection *con)
{
	con->flags |= 0x0F;
	if (con->sock && con->sock->sk)
		con->sock->sk->sk_user_data = NULL;
}

static void free_conn(struct connection *con)
{
	close_connection(con, true, true, true);
	if (con->othercon)
		kmem_cache_free(con_cache, con->othercon);
	hlist_del(&con->list);
	kmem_cache_free(con_cache, con);
}

void dlm_lowcomms_stop(void)
{
	/* Set all the flags to prevent any
	   socket activity.
	*/
	mutex_lock(&connections_lock);
	dlm_allow_conn = 0;
	foreach_conn(stop_conn);
	clean_writequeues();
	foreach_conn(free_conn);
	mutex_unlock(&connections_lock);

	work_stop();

	kmem_cache_destroy(con_cache);
}

int dlm_lowcomms_start(void)
{
	int error = -EINVAL;
	struct connection *con;
	int i;

	for (i = 0; i < CONN_HASH_SIZE; i++)
		INIT_HLIST_HEAD(&connection_hash[i]);

	init_local();
	if (!dlm_local_count) {
		error = -ENOTCONN;
		log_print("no local IP address has been set");
		goto fail;
	}

	error = -ENOMEM;
	con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
				      __alignof__(struct connection), 0,
				      NULL);
	if (!con_cache)
		goto fail;

	error = work_start();
	if (error)
		goto fail_destroy;

	dlm_allow_conn = 1;

	/* Start listening */
	if (dlm_config.ci_protocol == 0)
		error = tcp_listen_for_all();
	else
		error = sctp_listen_for_all();
	if (error)
		goto fail_unlisten;

	return 0;

fail_unlisten:
	dlm_allow_conn = 0;
	con = nodeid2con(0,0);
	if (con) {
		close_connection(con, false, true, true);
		kmem_cache_free(con_cache, con);
	}
fail_destroy:
	kmem_cache_destroy(con_cache);
fail:
	return error;
}

void dlm_lowcomms_exit(void)
{
	struct dlm_node_addr *na, *safe;

	spin_lock(&dlm_node_addrs_spin);
	list_for_each_entry_safe(na, safe, &dlm_node_addrs, list) {
		list_del(&na->list);
		while (na->addr_count--)
			kfree(na->addr[na->addr_count]);
		kfree(na);
	}
	spin_unlock(&dlm_node_addrs_spin);
}