Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

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
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2009 The FreeBSD Foundation
 * Copyright (c) 2010-2011 Pawel Jakub Dawidek <pawel@dawidek.net>
 * All rights reserved.
 *
 * This software was developed by Pawel Jakub Dawidek under sponsorship from
 * the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/time.h>
#include <sys/bio.h>
#include <sys/disk.h>
#include <sys/stat.h>

#include <geom/gate/g_gate.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgeom.h>
#include <pthread.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

#include <activemap.h>
#include <nv.h>
#include <rangelock.h>

#include "control.h"
#include "event.h"
#include "hast.h"
#include "hast_proto.h"
#include "hastd.h"
#include "hooks.h"
#include "metadata.h"
#include "proto.h"
#include "pjdlog.h"
#include "refcnt.h"
#include "subr.h"
#include "synch.h"

/* The is only one remote component for now. */
#define	ISREMOTE(no)	((no) == 1)

struct hio {
	/*
	 * Number of components we are still waiting for.
	 * When this field goes to 0, we can send the request back to the
	 * kernel. Each component has to decrease this counter by one
	 * even on failure.
	 */
	refcnt_t		 hio_countdown;
	/*
	 * Each component has a place to store its own error.
	 * Once the request is handled by all components we can decide if the
	 * request overall is successful or not.
	 */
	int			*hio_errors;
	/*
	 * Structure used to communicate with GEOM Gate class.
	 */
	struct g_gate_ctl_io	 hio_ggio;
	/*
	 * Request was already confirmed to GEOM Gate.
	 */
	bool			 hio_done;
	/*
	 * Number of components we are still waiting before sending write
	 * completion ack to GEOM Gate. Used for memsync.
	 */
	refcnt_t		 hio_writecount;
	/*
	 * Memsync request was acknowleged by remote.
	 */
	bool			 hio_memsyncacked;
	/*
	 * Remember replication from the time the request was initiated,
	 * so we won't get confused when replication changes on reload.
	 */
	int			 hio_replication;
	TAILQ_ENTRY(hio)	*hio_next;
};
#define	hio_free_next	hio_next[0]
#define	hio_done_next	hio_next[0]

/*
 * Free list holds unused structures. When free list is empty, we have to wait
 * until some in-progress requests are freed.
 */
static TAILQ_HEAD(, hio) hio_free_list;
static size_t hio_free_list_size;
static pthread_mutex_t hio_free_list_lock;
static pthread_cond_t hio_free_list_cond;
/*
 * There is one send list for every component. One requests is placed on all
 * send lists - each component gets the same request, but each component is
 * responsible for managing his own send list.
 */
static TAILQ_HEAD(, hio) *hio_send_list;
static size_t *hio_send_list_size;
static pthread_mutex_t *hio_send_list_lock;
static pthread_cond_t *hio_send_list_cond;
#define	hio_send_local_list_size	hio_send_list_size[0]
#define	hio_send_remote_list_size	hio_send_list_size[1]
/*
 * There is one recv list for every component, although local components don't
 * use recv lists as local requests are done synchronously.
 */
static TAILQ_HEAD(, hio) *hio_recv_list;
static size_t *hio_recv_list_size;
static pthread_mutex_t *hio_recv_list_lock;
static pthread_cond_t *hio_recv_list_cond;
#define	hio_recv_remote_list_size	hio_recv_list_size[1]
/*
 * Request is placed on done list by the slowest component (the one that
 * decreased hio_countdown from 1 to 0).
 */
static TAILQ_HEAD(, hio) hio_done_list;
static size_t hio_done_list_size;
static pthread_mutex_t hio_done_list_lock;
static pthread_cond_t hio_done_list_cond;
/*
 * Structure below are for interaction with sync thread.
 */
static bool sync_inprogress;
static pthread_mutex_t sync_lock;
static pthread_cond_t sync_cond;
/*
 * The lock below allows to synchornize access to remote connections.
 */
static pthread_rwlock_t *hio_remote_lock;

/*
 * Lock to synchronize metadata updates. Also synchronize access to
 * hr_primary_localcnt and hr_primary_remotecnt fields.
 */
static pthread_mutex_t metadata_lock;

/*
 * Maximum number of outstanding I/O requests.
 */
#define	HAST_HIO_MAX	256
/*
 * Number of components. At this point there are only two components: local
 * and remote, but in the future it might be possible to use multiple local
 * and remote components.
 */
#define	HAST_NCOMPONENTS	2

#define	ISCONNECTED(res, no)	\
	((res)->hr_remotein != NULL && (res)->hr_remoteout != NULL)

#define	QUEUE_INSERT1(hio, name, ncomp)	do {				\
	mtx_lock(&hio_##name##_list_lock[(ncomp)]);			\
	if (TAILQ_EMPTY(&hio_##name##_list[(ncomp)]))			\
		cv_broadcast(&hio_##name##_list_cond[(ncomp)]);		\
	TAILQ_INSERT_TAIL(&hio_##name##_list[(ncomp)], (hio),		\
	    hio_next[(ncomp)]);						\
	hio_##name##_list_size[(ncomp)]++;				\
	mtx_unlock(&hio_##name##_list_lock[(ncomp)]);			\
} while (0)
#define	QUEUE_INSERT2(hio, name)	do {				\
	mtx_lock(&hio_##name##_list_lock);				\
	if (TAILQ_EMPTY(&hio_##name##_list))				\
		cv_broadcast(&hio_##name##_list_cond);			\
	TAILQ_INSERT_TAIL(&hio_##name##_list, (hio), hio_##name##_next);\
	hio_##name##_list_size++;					\
	mtx_unlock(&hio_##name##_list_lock);				\
} while (0)
#define	QUEUE_TAKE1(hio, name, ncomp, timeout)	do {			\
	bool _last;							\
									\
	mtx_lock(&hio_##name##_list_lock[(ncomp)]);			\
	_last = false;							\
	while (((hio) = TAILQ_FIRST(&hio_##name##_list[(ncomp)])) == NULL && !_last) { \
		cv_timedwait(&hio_##name##_list_cond[(ncomp)],		\
		    &hio_##name##_list_lock[(ncomp)], (timeout));	\
		if ((timeout) != 0)					\
			_last = true;					\
	}								\
	if (hio != NULL) {						\
		PJDLOG_ASSERT(hio_##name##_list_size[(ncomp)] != 0);	\
		hio_##name##_list_size[(ncomp)]--;			\
		TAILQ_REMOVE(&hio_##name##_list[(ncomp)], (hio),	\
		    hio_next[(ncomp)]);					\
	}								\
	mtx_unlock(&hio_##name##_list_lock[(ncomp)]);			\
} while (0)
#define	QUEUE_TAKE2(hio, name)	do {					\
	mtx_lock(&hio_##name##_list_lock);				\
	while (((hio) = TAILQ_FIRST(&hio_##name##_list)) == NULL) {	\
		cv_wait(&hio_##name##_list_cond,			\
		    &hio_##name##_list_lock);				\
	}								\
	PJDLOG_ASSERT(hio_##name##_list_size != 0);			\
	hio_##name##_list_size--;					\
	TAILQ_REMOVE(&hio_##name##_list, (hio), hio_##name##_next);	\
	mtx_unlock(&hio_##name##_list_lock);				\
} while (0)

#define ISFULLSYNC(hio)	((hio)->hio_replication == HAST_REPLICATION_FULLSYNC)
#define ISMEMSYNC(hio)	((hio)->hio_replication == HAST_REPLICATION_MEMSYNC)
#define ISASYNC(hio)	((hio)->hio_replication == HAST_REPLICATION_ASYNC)

#define	SYNCREQ(hio)		do {					\
	(hio)->hio_ggio.gctl_unit = -1;					\
	(hio)->hio_ggio.gctl_seq = 1;					\
} while (0)
#define	ISSYNCREQ(hio)		((hio)->hio_ggio.gctl_unit == -1)
#define	SYNCREQDONE(hio)	do { (hio)->hio_ggio.gctl_unit = -2; } while (0)
#define	ISSYNCREQDONE(hio)	((hio)->hio_ggio.gctl_unit == -2)

#define ISMEMSYNCWRITE(hio)	(ISMEMSYNC(hio) &&			\
	    (hio)->hio_ggio.gctl_cmd == BIO_WRITE && !ISSYNCREQ(hio))

static struct hast_resource *gres;

static pthread_mutex_t range_lock;
static struct rangelocks *range_regular;
static bool range_regular_wait;
static pthread_cond_t range_regular_cond;
static struct rangelocks *range_sync;
static bool range_sync_wait;
static pthread_cond_t range_sync_cond;
static bool fullystarted;

static void *ggate_recv_thread(void *arg);
static void *local_send_thread(void *arg);
static void *remote_send_thread(void *arg);
static void *remote_recv_thread(void *arg);
static void *ggate_send_thread(void *arg);
static void *sync_thread(void *arg);
static void *guard_thread(void *arg);

static void
output_status_aux(struct nv *nvout)
{

	nv_add_uint64(nvout, (uint64_t)hio_free_list_size,
	    "idle_queue_size");
	nv_add_uint64(nvout, (uint64_t)hio_send_local_list_size,
	    "local_queue_size");
	nv_add_uint64(nvout, (uint64_t)hio_send_remote_list_size,
	    "send_queue_size");
	nv_add_uint64(nvout, (uint64_t)hio_recv_remote_list_size,
	    "recv_queue_size");
	nv_add_uint64(nvout, (uint64_t)hio_done_list_size,
	    "done_queue_size");
}

static void
cleanup(struct hast_resource *res)
{
	int rerrno;

	/* Remember errno. */
	rerrno = errno;

	/* Destroy ggate provider if we created one. */
	if (res->hr_ggateunit >= 0) {
		struct g_gate_ctl_destroy ggiod;

		bzero(&ggiod, sizeof(ggiod));
		ggiod.gctl_version = G_GATE_VERSION;
		ggiod.gctl_unit = res->hr_ggateunit;
		ggiod.gctl_force = 1;
		if (ioctl(res->hr_ggatefd, G_GATE_CMD_DESTROY, &ggiod) == -1) {
			pjdlog_errno(LOG_WARNING,
			    "Unable to destroy hast/%s device",
			    res->hr_provname);
		}
		res->hr_ggateunit = -1;
	}

	/* Restore errno. */
	errno = rerrno;
}

static __dead2 void
primary_exit(int exitcode, const char *fmt, ...)
{
	va_list ap;

	PJDLOG_ASSERT(exitcode != EX_OK);
	va_start(ap, fmt);
	pjdlogv_errno(LOG_ERR, fmt, ap);
	va_end(ap);
	cleanup(gres);
	exit(exitcode);
}

static __dead2 void
primary_exitx(int exitcode, const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	pjdlogv(exitcode == EX_OK ? LOG_INFO : LOG_ERR, fmt, ap);
	va_end(ap);
	cleanup(gres);
	exit(exitcode);
}

static int
hast_activemap_flush(struct hast_resource *res) __unlocks(res->hr_amp_lock)
{
	const unsigned char *buf;
	size_t size;
	int ret;

	mtx_lock(&res->hr_amp_diskmap_lock);
	buf = activemap_bitmap(res->hr_amp, &size);
	mtx_unlock(&res->hr_amp_lock);
	PJDLOG_ASSERT(buf != NULL);
	PJDLOG_ASSERT((size % res->hr_local_sectorsize) == 0);
	ret = 0;
	if (pwrite(res->hr_localfd, buf, size, METADATA_SIZE) !=
	    (ssize_t)size) {
		pjdlog_errno(LOG_ERR, "Unable to flush activemap to disk");
		res->hr_stat_activemap_write_error++;
		ret = -1;
	}
	if (ret == 0 && res->hr_metaflush == 1 &&
	    g_flush(res->hr_localfd) == -1) {
		if (errno == EOPNOTSUPP) {
			pjdlog_warning("The %s provider doesn't support flushing write cache. Disabling it.",
			    res->hr_localpath);
			res->hr_metaflush = 0;
		} else {
			pjdlog_errno(LOG_ERR,
			    "Unable to flush disk cache on activemap update");
			res->hr_stat_activemap_flush_error++;
			ret = -1;
		}
	}
	mtx_unlock(&res->hr_amp_diskmap_lock);
	return (ret);
}

static bool
real_remote(const struct hast_resource *res)
{

	return (strcmp(res->hr_remoteaddr, "none") != 0);
}

static void
init_environment(struct hast_resource *res __unused)
{
	struct hio *hio;
	unsigned int ii, ncomps;

	/*
	 * In the future it might be per-resource value.
	 */
	ncomps = HAST_NCOMPONENTS;

	/*
	 * Allocate memory needed by lists.
	 */
	hio_send_list = malloc(sizeof(hio_send_list[0]) * ncomps);
	if (hio_send_list == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for send lists.",
		    sizeof(hio_send_list[0]) * ncomps);
	}
	hio_send_list_size = malloc(sizeof(hio_send_list_size[0]) * ncomps);
	if (hio_send_list_size == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for send list counters.",
		    sizeof(hio_send_list_size[0]) * ncomps);
	}
	hio_send_list_lock = malloc(sizeof(hio_send_list_lock[0]) * ncomps);
	if (hio_send_list_lock == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for send list locks.",
		    sizeof(hio_send_list_lock[0]) * ncomps);
	}
	hio_send_list_cond = malloc(sizeof(hio_send_list_cond[0]) * ncomps);
	if (hio_send_list_cond == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for send list condition variables.",
		    sizeof(hio_send_list_cond[0]) * ncomps);
	}
	hio_recv_list = malloc(sizeof(hio_recv_list[0]) * ncomps);
	if (hio_recv_list == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for recv lists.",
		    sizeof(hio_recv_list[0]) * ncomps);
	}
	hio_recv_list_size = malloc(sizeof(hio_recv_list_size[0]) * ncomps);
	if (hio_recv_list_size == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for recv list counters.",
		    sizeof(hio_recv_list_size[0]) * ncomps);
	}
	hio_recv_list_lock = malloc(sizeof(hio_recv_list_lock[0]) * ncomps);
	if (hio_recv_list_lock == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for recv list locks.",
		    sizeof(hio_recv_list_lock[0]) * ncomps);
	}
	hio_recv_list_cond = malloc(sizeof(hio_recv_list_cond[0]) * ncomps);
	if (hio_recv_list_cond == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for recv list condition variables.",
		    sizeof(hio_recv_list_cond[0]) * ncomps);
	}
	hio_remote_lock = malloc(sizeof(hio_remote_lock[0]) * ncomps);
	if (hio_remote_lock == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate %zu bytes of memory for remote connections locks.",
		    sizeof(hio_remote_lock[0]) * ncomps);
	}

	/*
	 * Initialize lists, their counters, locks and condition variables.
	 */
	TAILQ_INIT(&hio_free_list);
	mtx_init(&hio_free_list_lock);
	cv_init(&hio_free_list_cond);
	for (ii = 0; ii < HAST_NCOMPONENTS; ii++) {
		TAILQ_INIT(&hio_send_list[ii]);
		hio_send_list_size[ii] = 0;
		mtx_init(&hio_send_list_lock[ii]);
		cv_init(&hio_send_list_cond[ii]);
		TAILQ_INIT(&hio_recv_list[ii]);
		hio_recv_list_size[ii] = 0;
		mtx_init(&hio_recv_list_lock[ii]);
		cv_init(&hio_recv_list_cond[ii]);
		rw_init(&hio_remote_lock[ii]);
	}
	TAILQ_INIT(&hio_done_list);
	mtx_init(&hio_done_list_lock);
	cv_init(&hio_done_list_cond);
	mtx_init(&metadata_lock);

	/*
	 * Allocate requests pool and initialize requests.
	 */
	for (ii = 0; ii < HAST_HIO_MAX; ii++) {
		hio = malloc(sizeof(*hio));
		if (hio == NULL) {
			primary_exitx(EX_TEMPFAIL,
			    "Unable to allocate %zu bytes of memory for hio request.",
			    sizeof(*hio));
		}
		refcnt_init(&hio->hio_countdown, 0);
		hio->hio_errors = malloc(sizeof(hio->hio_errors[0]) * ncomps);
		if (hio->hio_errors == NULL) {
			primary_exitx(EX_TEMPFAIL,
			    "Unable allocate %zu bytes of memory for hio errors.",
			    sizeof(hio->hio_errors[0]) * ncomps);
		}
		hio->hio_next = malloc(sizeof(hio->hio_next[0]) * ncomps);
		if (hio->hio_next == NULL) {
			primary_exitx(EX_TEMPFAIL,
			    "Unable allocate %zu bytes of memory for hio_next field.",
			    sizeof(hio->hio_next[0]) * ncomps);
		}
		hio->hio_ggio.gctl_version = G_GATE_VERSION;
		hio->hio_ggio.gctl_data = malloc(MAXPHYS);
		if (hio->hio_ggio.gctl_data == NULL) {
			primary_exitx(EX_TEMPFAIL,
			    "Unable to allocate %zu bytes of memory for gctl_data.",
			    MAXPHYS);
		}
		hio->hio_ggio.gctl_length = MAXPHYS;
		hio->hio_ggio.gctl_error = 0;
		TAILQ_INSERT_HEAD(&hio_free_list, hio, hio_free_next);
		hio_free_list_size++;
	}
}

static bool
init_resuid(struct hast_resource *res)
{

	mtx_lock(&metadata_lock);
	if (res->hr_resuid != 0) {
		mtx_unlock(&metadata_lock);
		return (false);
	} else {
		/* Initialize unique resource identifier. */
		arc4random_buf(&res->hr_resuid, sizeof(res->hr_resuid));
		mtx_unlock(&metadata_lock);
		if (metadata_write(res) == -1)
			exit(EX_NOINPUT);
		return (true);
	}
}

static void
init_local(struct hast_resource *res)
{
	unsigned char *buf;
	size_t mapsize;

	if (metadata_read(res, true) == -1)
		exit(EX_NOINPUT);
	mtx_init(&res->hr_amp_lock);
	if (activemap_init(&res->hr_amp, res->hr_datasize, res->hr_extentsize,
	    res->hr_local_sectorsize, res->hr_keepdirty) == -1) {
		primary_exit(EX_TEMPFAIL, "Unable to create activemap");
	}
	mtx_init(&range_lock);
	cv_init(&range_regular_cond);
	if (rangelock_init(&range_regular) == -1)
		primary_exit(EX_TEMPFAIL, "Unable to create regular range lock");
	cv_init(&range_sync_cond);
	if (rangelock_init(&range_sync) == -1)
		primary_exit(EX_TEMPFAIL, "Unable to create sync range lock");
	mapsize = activemap_ondisk_size(res->hr_amp);
	buf = calloc(1, mapsize);
	if (buf == NULL) {
		primary_exitx(EX_TEMPFAIL,
		    "Unable to allocate buffer for activemap.");
	}
	if (pread(res->hr_localfd, buf, mapsize, METADATA_SIZE) !=
	    (ssize_t)mapsize) {
		primary_exit(EX_NOINPUT, "Unable to read activemap");
	}
	activemap_copyin(res->hr_amp, buf, mapsize);
	free(buf);
	if (res->hr_resuid != 0)
		return;
	/*
	 * We're using provider for the first time. Initialize local and remote
	 * counters. We don't initialize resuid here, as we want to do it just
	 * in time. The reason for this is that we want to inform secondary
	 * that there were no writes yet, so there is no need to synchronize
	 * anything.
	 */
	res->hr_primary_localcnt = 0;
	res->hr_primary_remotecnt = 0;
	if (metadata_write(res) == -1)
		exit(EX_NOINPUT);
}

static int
primary_connect(struct hast_resource *res, struct proto_conn **connp)
{
	struct proto_conn *conn;
	int16_t val;

	val = 1;
	if (proto_send(res->hr_conn, &val, sizeof(val)) == -1) {
		primary_exit(EX_TEMPFAIL,
		    "Unable to send connection request to parent");
	}
	if (proto_recv(res->hr_conn, &val, sizeof(val)) == -1) {
		primary_exit(EX_TEMPFAIL,
		    "Unable to receive reply to connection request from parent");
	}
	if (val != 0) {
		errno = val;
		pjdlog_errno(LOG_WARNING, "Unable to connect to %s",
		    res->hr_remoteaddr);
		return (-1);
	}
	if (proto_connection_recv(res->hr_conn, true, &conn) == -1) {
		primary_exit(EX_TEMPFAIL,
		    "Unable to receive connection from parent");
	}
	if (proto_connect_wait(conn, res->hr_timeout) == -1) {
		pjdlog_errno(LOG_WARNING, "Unable to connect to %s",
		    res->hr_remoteaddr);
		proto_close(conn);
		return (-1);
	}
	/* Error in setting timeout is not critical, but why should it fail? */
	if (proto_timeout(conn, res->hr_timeout) == -1)
		pjdlog_errno(LOG_WARNING, "Unable to set connection timeout");

	*connp = conn;

	return (0);
}

/*
 * Function instructs GEOM_GATE to handle reads directly from within the kernel.
 */
static void
enable_direct_reads(struct hast_resource *res)
{
	struct g_gate_ctl_modify ggiomodify;

	bzero(&ggiomodify, sizeof(ggiomodify));
	ggiomodify.gctl_version = G_GATE_VERSION;
	ggiomodify.gctl_unit = res->hr_ggateunit;
	ggiomodify.gctl_modify = GG_MODIFY_READPROV | GG_MODIFY_READOFFSET;
	strlcpy(ggiomodify.gctl_readprov, res->hr_localpath,
	    sizeof(ggiomodify.gctl_readprov));
	ggiomodify.gctl_readoffset = res->hr_localoff;
	if (ioctl(res->hr_ggatefd, G_GATE_CMD_MODIFY, &ggiomodify) == 0)
		pjdlog_debug(1, "Direct reads enabled.");
	else
		pjdlog_errno(LOG_WARNING, "Failed to enable direct reads");
}

static int
init_remote(struct hast_resource *res, struct proto_conn **inp,
    struct proto_conn **outp)
{
	struct proto_conn *in, *out;
	struct nv *nvout, *nvin;
	const unsigned char *token;
	unsigned char *map;
	const char *errmsg;
	int32_t extentsize;
	int64_t datasize;
	uint32_t mapsize;
	uint8_t version;
	size_t size;
	int error;

	PJDLOG_ASSERT((inp == NULL && outp == NULL) || (inp != NULL && outp != NULL));
	PJDLOG_ASSERT(real_remote(res));

	in = out = NULL;
	errmsg = NULL;

	if (primary_connect(res, &out) == -1)
		return (ECONNREFUSED);

	error = ECONNABORTED;

	/*
	 * First handshake step.
	 * Setup outgoing connection with remote node.
	 */
	nvout = nv_alloc();
	nv_add_string(nvout, res->hr_name, "resource");
	nv_add_uint8(nvout, HAST_PROTO_VERSION, "version");
	if (nv_error(nvout) != 0) {
		pjdlog_common(LOG_WARNING, 0, nv_error(nvout),
		    "Unable to allocate header for connection with %s",
		    res->hr_remoteaddr);
		nv_free(nvout);
		goto close;
	}
	if (hast_proto_send(res, out, nvout, NULL, 0) == -1) {
		pjdlog_errno(LOG_WARNING,
		    "Unable to send handshake header to %s",
		    res->hr_remoteaddr);
		nv_free(nvout);
		goto close;
	}
	nv_free(nvout);
	if (hast_proto_recv_hdr(out, &nvin) == -1) {
		pjdlog_errno(LOG_WARNING,
		    "Unable to receive handshake header from %s",
		    res->hr_remoteaddr);
		goto close;
	}
	errmsg = nv_get_string(nvin, "errmsg");
	if (errmsg != NULL) {
		pjdlog_warning("%s", errmsg);
		if (nv_exists(nvin, "wait"))
			error = EBUSY;
		nv_free(nvin);
		goto close;
	}
	version = nv_get_uint8(nvin, "version");
	if (version == 0) {
		/*
		 * If no version is sent, it means this is protocol version 1.
		 */
		version = 1;
	}
	if (version > HAST_PROTO_VERSION) {
		pjdlog_warning("Invalid version received (%hhu).", version);
		nv_free(nvin);
		goto close;
	}
	res->hr_version = version;
	pjdlog_debug(1, "Negotiated protocol version %d.", res->hr_version);
	token = nv_get_uint8_array(nvin, &size, "token");
	if (token == NULL) {
		pjdlog_warning("Handshake header from %s has no 'token' field.",
		    res->hr_remoteaddr);
		nv_free(nvin);
		goto close;
	}
	if (size != sizeof(res->hr_token)) {
		pjdlog_warning("Handshake header from %s contains 'token' of wrong size (got %zu, expected %zu).",
		    res->hr_remoteaddr, size, sizeof(res->hr_token));
		nv_free(nvin);
		goto close;
	}
	bcopy(token, res->hr_token, sizeof(res->hr_token));
	nv_free(nvin);

	/*
	 * Second handshake step.
	 * Setup incoming connection with remote node.
	 */
	if (primary_connect(res, &in) == -1)
		goto close;

	nvout = nv_alloc();
	nv_add_string(nvout, res->hr_name, "resource");
	nv_add_uint8_array(nvout, res->hr_token, sizeof(res->hr_token),
	    "token");
	if (res->hr_resuid == 0) {
		/*
		 * The resuid field was not yet initialized.
		 * Because we do synchronization inside init_resuid(), it is
		 * possible that someone already initialized it, the function
		 * will return false then, but if we successfully initialized
		 * it, we will get true. True means that there were no writes
		 * to this resource yet and we want to inform secondary that
		 * synchronization is not needed by sending "virgin" argument.
		 */
		if (init_resuid(res))
			nv_add_int8(nvout, 1, "virgin");
	}
	nv_add_uint64(nvout, res->hr_resuid, "resuid");
	nv_add_uint64(nvout, res->hr_primary_localcnt, "localcnt");
	nv_add_uint64(nvout, res->hr_primary_remotecnt, "remotecnt");
	if (nv_error(nvout) != 0) {
		pjdlog_common(LOG_WARNING, 0, nv_error(nvout),
		    "Unable to allocate header for connection with %s",
		    res->hr_remoteaddr);
		nv_free(nvout);
		goto close;
	}
	if (hast_proto_send(res, in, nvout, NULL, 0) == -1) {
		pjdlog_errno(LOG_WARNING,
		    "Unable to send handshake header to %s",
		    res->hr_remoteaddr);
		nv_free(nvout);
		goto close;
	}
	nv_free(nvout);
	if (hast_proto_recv_hdr(out, &nvin) == -1) {
		pjdlog_errno(LOG_WARNING,
		    "Unable to receive handshake header from %s",
		    res->hr_remoteaddr);
		goto close;
	}
	errmsg = nv_get_string(nvin, "errmsg");
	if (errmsg != NULL) {
		pjdlog_warning("%s", errmsg);
		nv_free(nvin);
		goto close;
	}
	datasize = nv_get_int64(nvin, "datasize");
	if (datasize != res->hr_datasize) {
		pjdlog_warning("Data size differs between nodes (local=%jd, remote=%jd).",
		    (intmax_t)res->hr_datasize, (intmax_t)datasize);
		nv_free(nvin);
		goto close;
	}
	extentsize = nv_get_int32(nvin, "extentsize");
	if (extentsize != res->hr_extentsize) {
		pjdlog_warning("Extent size differs between nodes (local=%zd, remote=%zd).",
		    (ssize_t)res->hr_extentsize, (ssize_t)extentsize);
		nv_free(nvin);
		goto close;
	}
	res->hr_secondary_localcnt = nv_get_uint64(nvin, "localcnt");
	res->hr_secondary_remotecnt = nv_get_uint64(nvin, "remotecnt");
	res->hr_syncsrc = nv_get_uint8(nvin, "syncsrc");
	if (res->hr_syncsrc == HAST_SYNCSRC_PRIMARY)
		enable_direct_reads(res);
	if (nv_exists(nvin, "virgin")) {
		/*
		 * Secondary was reinitialized, bump localcnt if it is 0 as
		 * only we have the data.
		 */
		PJDLOG_ASSERT(res->hr_syncsrc == HAST_SYNCSRC_PRIMARY);
		PJDLOG_ASSERT(res->hr_secondary_localcnt == 0);

		if (res->hr_primary_localcnt == 0) {
			PJDLOG_ASSERT(res->hr_secondary_remotecnt == 0);

			mtx_lock(&metadata_lock);
			res->hr_primary_localcnt++;
			pjdlog_debug(1, "Increasing localcnt to %ju.",
			    (uintmax_t)res->hr_primary_localcnt);
			(void)metadata_write(res);
			mtx_unlock(&metadata_lock);
		}
	}
	map = NULL;
	mapsize = nv_get_uint32(nvin, "mapsize");
	if (mapsize > 0) {
		map = malloc(mapsize);
		if (map == NULL) {
			pjdlog_error("Unable to allocate memory for remote activemap (mapsize=%ju).",
			    (uintmax_t)mapsize);
			nv_free(nvin);
			goto close;
		}
		/*
		 * Remote node have some dirty extents on its own, lets
		 * download its activemap.
		 */
		if (hast_proto_recv_data(res, out, nvin, map,
		    mapsize) == -1) {
			pjdlog_errno(LOG_ERR,
			    "Unable to receive remote activemap");
			nv_free(nvin);
			free(map);
			goto close;
		}
		mtx_lock(&res->hr_amp_lock);
		/*
		 * Merge local and remote bitmaps.
		 */
		activemap_merge(res->hr_amp, map, mapsize);
		free(map);
		/*
		 * Now that we merged bitmaps from both nodes, flush it to the
		 * disk before we start to synchronize.
		 */
		(void)hast_activemap_flush(res);
	}
	nv_free(nvin);
#ifdef notyet
	/* Setup directions. */
	if (proto_send(out, NULL, 0) == -1)
		pjdlog_errno(LOG_WARNING, "Unable to set connection direction");
	if (proto_recv(in, NULL, 0) == -1)
		pjdlog_errno(LOG_WARNING, "Unable to set connection direction");
#endif
	pjdlog_info("Connected to %s.", res->hr_remoteaddr);
	if (res->hr_original_replication == HAST_REPLICATION_MEMSYNC &&
	    res->hr_version < 2) {
		pjdlog_warning("The 'memsync' replication mode is not supported by the remote node, falling back to 'fullsync' mode.");
		res->hr_replication = HAST_REPLICATION_FULLSYNC;
	} else if (res->hr_replication != res->hr_original_replication) {
		/*
		 * This is in case hastd disconnected and was upgraded.
		 */
		res->hr_replication = res->hr_original_replication;
	}
	if (inp != NULL && outp != NULL) {
		*inp = in;
		*outp = out;
	} else {
		res->hr_remotein = in;
		res->hr_remoteout = out;
	}
	event_send(res, EVENT_CONNECT);
	return (0);
close:
	if (errmsg != NULL && strcmp(errmsg, "Split-brain condition!") == 0)
		event_send(res, EVENT_SPLITBRAIN);
	proto_close(out);
	if (in != NULL)
		proto_close(in);
	return (error);
}

static void
sync_start(void)
{

	mtx_lock(&sync_lock);
	sync_inprogress = true;
	mtx_unlock(&sync_lock);
	cv_signal(&sync_cond);
}

static void
sync_stop(void)
{

	mtx_lock(&sync_lock);
	if (sync_inprogress)
		sync_inprogress = false;
	mtx_unlock(&sync_lock);
}

static void
init_ggate(struct hast_resource *res)
{
	struct g_gate_ctl_create ggiocreate;
	struct g_gate_ctl_cancel ggiocancel;

	/*
	 * We communicate with ggate via /dev/ggctl. Open it.
	 */
	res->hr_ggatefd = open("/dev/" G_GATE_CTL_NAME, O_RDWR);
	if (res->hr_ggatefd == -1)
		primary_exit(EX_OSFILE, "Unable to open /dev/" G_GATE_CTL_NAME);
	/*
	 * Create provider before trying to connect, as connection failure
	 * is not critical, but may take some time.
	 */
	bzero(&ggiocreate, sizeof(ggiocreate));
	ggiocreate.gctl_version = G_GATE_VERSION;
	ggiocreate.gctl_mediasize = res->hr_datasize;
	ggiocreate.gctl_sectorsize = res->hr_local_sectorsize;
	ggiocreate.gctl_flags = 0;
	ggiocreate.gctl_maxcount = 0;
	ggiocreate.gctl_timeout = 0;
	ggiocreate.gctl_unit = G_GATE_NAME_GIVEN;
	snprintf(ggiocreate.gctl_name, sizeof(ggiocreate.gctl_name), "hast/%s",
	    res->hr_provname);
	if (ioctl(res->hr_ggatefd, G_GATE_CMD_CREATE, &ggiocreate) == 0) {
		pjdlog_info("Device hast/%s created.", res->hr_provname);
		res->hr_ggateunit = ggiocreate.gctl_unit;
		return;
	}
	if (errno != EEXIST) {
		primary_exit(EX_OSERR, "Unable to create hast/%s device",
		    res->hr_provname);
	}
	pjdlog_debug(1,
	    "Device hast/%s already exists, we will try to take it over.",
	    res->hr_provname);
	/*
	 * If we received EEXIST, we assume that the process who created the
	 * provider died and didn't clean up. In that case we will start from
	 * where he left of.
	 */
	bzero(&ggiocancel, sizeof(ggiocancel));
	ggiocancel.gctl_version = G_GATE_VERSION;
	ggiocancel.gctl_unit = G_GATE_NAME_GIVEN;
	snprintf(ggiocancel.gctl_name, sizeof(ggiocancel.gctl_name), "hast/%s",
	    res->hr_provname);
	if (ioctl(res->hr_ggatefd, G_GATE_CMD_CANCEL, &ggiocancel) == 0) {
		pjdlog_info("Device hast/%s recovered.", res->hr_provname);
		res->hr_ggateunit = ggiocancel.gctl_unit;
		return;
	}
	primary_exit(EX_OSERR, "Unable to take over hast/%s device",
	    res->hr_provname);
}

void
hastd_primary(struct hast_resource *res)
{
	pthread_t td;
	pid_t pid;
	int error, mode, debuglevel;

	/*
	 * Create communication channel for sending control commands from
	 * parent to child.
	 */
	if (proto_client(NULL, "socketpair://", &res->hr_ctrl) == -1) {
		/* TODO: There's no need for this to be fatal error. */
		KEEP_ERRNO((void)pidfile_remove(pfh));
		pjdlog_exit(EX_OSERR,
		    "Unable to create control sockets between parent and child");
	}
	/*
	 * Create communication channel for sending events from child to parent.
	 */
	if (proto_client(NULL, "socketpair://", &res->hr_event) == -1) {
		/* TODO: There's no need for this to be fatal error. */
		KEEP_ERRNO((void)pidfile_remove(pfh));
		pjdlog_exit(EX_OSERR,
		    "Unable to create event sockets between child and parent");
	}
	/*
	 * Create communication channel for sending connection requests from
	 * child to parent.
	 */
	if (proto_client(NULL, "socketpair://", &res->hr_conn) == -1) {
		/* TODO: There's no need for this to be fatal error. */
		KEEP_ERRNO((void)pidfile_remove(pfh));
		pjdlog_exit(EX_OSERR,
		    "Unable to create connection sockets between child and parent");
	}

	pid = fork();
	if (pid == -1) {
		/* TODO: There's no need for this to be fatal error. */
		KEEP_ERRNO((void)pidfile_remove(pfh));
		pjdlog_exit(EX_TEMPFAIL, "Unable to fork");
	}

	if (pid > 0) {
		/* This is parent. */
		/* Declare that we are receiver. */
		proto_recv(res->hr_event, NULL, 0);
		proto_recv(res->hr_conn, NULL, 0);
		/* Declare that we are sender. */
		proto_send(res->hr_ctrl, NULL, 0);
		res->hr_workerpid = pid;
		return;
	}

	gres = res;
	res->output_status_aux = output_status_aux;
	mode = pjdlog_mode_get();
	debuglevel = pjdlog_debug_get();

	/* Declare that we are sender. */
	proto_send(res->hr_event, NULL, 0);
	proto_send(res->hr_conn, NULL, 0);
	/* Declare that we are receiver. */
	proto_recv(res->hr_ctrl, NULL, 0);
	descriptors_cleanup(res);

	descriptors_assert(res, mode);

	pjdlog_init(mode);
	pjdlog_debug_set(debuglevel);
	pjdlog_prefix_set("[%s] (%s) ", res->hr_name, role2str(res->hr_role));
	setproctitle("%s (%s)", res->hr_name, role2str(res->hr_role));

	init_local(res);
	init_ggate(res);
	init_environment(res);

	if (drop_privs(res) != 0) {
		cleanup(res);
		exit(EX_CONFIG);
	}
	pjdlog_info("Privileges successfully dropped.");

	/*
	 * Create the guard thread first, so we can handle signals from the
	 * very beginning.
	 */
	error = pthread_create(&td, NULL, guard_thread, res);
	PJDLOG_ASSERT(error == 0);
	/*
	 * Create the control thread before sending any event to the parent,
	 * as we can deadlock when parent sends control request to worker,
	 * but worker has no control thread started yet, so parent waits.
	 * In the meantime worker sends an event to the parent, but parent
	 * is unable to handle the event, because it waits for control
	 * request response.
	 */
	error = pthread_create(&td, NULL, ctrl_thread, res);
	PJDLOG_ASSERT(error == 0);
	if (real_remote(res)) {
		error = init_remote(res, NULL, NULL);
		if (error == 0) {
			sync_start();
		} else if (error == EBUSY) {
			time_t start = time(NULL);

			pjdlog_warning("Waiting for remote node to become %s for %ds.",
			    role2str(HAST_ROLE_SECONDARY),
			    res->hr_timeout);
			for (;;) {
				sleep(1);
				error = init_remote(res, NULL, NULL);
				if (error != EBUSY)
					break;
				if (time(NULL) > start + res->hr_timeout)
					break;
			}
			if (error == EBUSY) {
				pjdlog_warning("Remote node is still %s, starting anyway.",
				    role2str(HAST_ROLE_PRIMARY));
			}
		}
	}
	error = pthread_create(&td, NULL, ggate_recv_thread, res);
	PJDLOG_ASSERT(error == 0);
	error = pthread_create(&td, NULL, local_send_thread, res);
	PJDLOG_ASSERT(error == 0);
	error = pthread_create(&td, NULL, remote_send_thread, res);
	PJDLOG_ASSERT(error == 0);
	error = pthread_create(&td, NULL, remote_recv_thread, res);
	PJDLOG_ASSERT(error == 0);
	error = pthread_create(&td, NULL, ggate_send_thread, res);
	PJDLOG_ASSERT(error == 0);
	fullystarted = true;
	(void)sync_thread(res);
}

static void
reqlog(int loglevel, int debuglevel, struct g_gate_ctl_io *ggio,
    const char *fmt, ...)
{
	char msg[1024];
	va_list ap;

	va_start(ap, fmt);
	(void)vsnprintf(msg, sizeof(msg), fmt, ap);
	va_end(ap);
	switch (ggio->gctl_cmd) {
	case BIO_READ:
		(void)snprlcat(msg, sizeof(msg), "READ(%ju, %ju).",
		    (uintmax_t)ggio->gctl_offset, (uintmax_t)ggio->gctl_length);
		break;
	case BIO_DELETE:
		(void)snprlcat(msg, sizeof(msg), "DELETE(%ju, %ju).",
		    (uintmax_t)ggio->gctl_offset, (uintmax_t)ggio->gctl_length);
		break;
	case BIO_FLUSH:
		(void)snprlcat(msg, sizeof(msg), "FLUSH.");
		break;
	case BIO_WRITE:
		(void)snprlcat(msg, sizeof(msg), "WRITE(%ju, %ju).",
		    (uintmax_t)ggio->gctl_offset, (uintmax_t)ggio->gctl_length);
		break;
	default:
		(void)snprlcat(msg, sizeof(msg), "UNKNOWN(%u).",
		    (unsigned int)ggio->gctl_cmd);
		break;
	}
	pjdlog_common(loglevel, debuglevel, -1, "%s", msg);
}

static void
remote_close(struct hast_resource *res, int ncomp)
{

	rw_wlock(&hio_remote_lock[ncomp]);
	/*
	 * Check for a race between dropping rlock and acquiring wlock -
	 * another thread can close connection in-between.
	 */
	if (!ISCONNECTED(res, ncomp)) {
		PJDLOG_ASSERT(res->hr_remotein == NULL);
		PJDLOG_ASSERT(res->hr_remoteout == NULL);
		rw_unlock(&hio_remote_lock[ncomp]);
		return;
	}

	PJDLOG_ASSERT(res->hr_remotein != NULL);
	PJDLOG_ASSERT(res->hr_remoteout != NULL);

	pjdlog_debug(2, "Closing incoming connection to %s.",
	    res->hr_remoteaddr);
	proto_close(res->hr_remotein);
	res->hr_remotein = NULL;
	pjdlog_debug(2, "Closing outgoing connection to %s.",
	    res->hr_remoteaddr);
	proto_close(res->hr_remoteout);
	res->hr_remoteout = NULL;

	rw_unlock(&hio_remote_lock[ncomp]);

	pjdlog_warning("Disconnected from %s.", res->hr_remoteaddr);

	/*
	 * Stop synchronization if in-progress.
	 */
	sync_stop();

	event_send(res, EVENT_DISCONNECT);
}

/*
 * Acknowledge write completion to the kernel, but don't update activemap yet.
 */
static void
write_complete(struct hast_resource *res, struct hio *hio)
{
	struct g_gate_ctl_io *ggio;
	unsigned int ncomp;

	PJDLOG_ASSERT(!hio->hio_done);

	ggio = &hio->hio_ggio;
	PJDLOG_ASSERT(ggio->gctl_cmd == BIO_WRITE);

	/*
	 * Bump local count if this is first write after
	 * connection failure with remote node.
	 */
	ncomp = 1;
	rw_rlock(&hio_remote_lock[ncomp]);
	if (!ISCONNECTED(res, ncomp)) {
		mtx_lock(&metadata_lock);
		if (res->hr_primary_localcnt == res->hr_secondary_remotecnt) {
			res->hr_primary_localcnt++;
			pjdlog_debug(1, "Increasing localcnt to %ju.",
			    (uintmax_t)res->hr_primary_localcnt);
			(void)metadata_write(res);
		}
		mtx_unlock(&metadata_lock);
	}
	rw_unlock(&hio_remote_lock[ncomp]);
	if (ioctl(res->hr_ggatefd, G_GATE_CMD_DONE, ggio) == -1)
		primary_exit(EX_OSERR, "G_GATE_CMD_DONE failed");
	hio->hio_done = true;
}

/*
 * Thread receives ggate I/O requests from the kernel and passes them to
 * appropriate threads:
 * WRITE - always goes to both local_send and remote_send threads
 * READ (when the block is up-to-date on local component) -
 *	only local_send thread
 * READ (when the block isn't up-to-date on local component) -
 *	only remote_send thread
 * DELETE - always goes to both local_send and remote_send threads
 * FLUSH - always goes to both local_send and remote_send threads
 */
static void *
ggate_recv_thread(void *arg)
{
	struct hast_resource *res = arg;
	struct g_gate_ctl_io *ggio;
	struct hio *hio;
	unsigned int ii, ncomp, ncomps;
	int error;

	for (;;) {
		pjdlog_debug(2, "ggate_recv: Taking free request.");
		QUEUE_TAKE2(hio, free);
		pjdlog_debug(2, "ggate_recv: (%p) Got free request.", hio);
		ggio = &hio->hio_ggio;
		ggio->gctl_unit = res->hr_ggateunit;
		ggio->gctl_length = MAXPHYS;
		ggio->gctl_error = 0;
		hio->hio_done = false;
		hio->hio_replication = res->hr_replication;
		pjdlog_debug(2,
		    "ggate_recv: (%p) Waiting for request from the kernel.",
		    hio);
		if (ioctl(res->hr_ggatefd, G_GATE_CMD_START, ggio) == -1) {
			if (sigexit_received)
				pthread_exit(NULL);
			primary_exit(EX_OSERR, "G_GATE_CMD_START failed");
		}
		error = ggio->gctl_error;
		switch (error) {
		case 0:
			break;
		case ECANCELED:
			/* Exit gracefully. */
			if (!sigexit_received) {
				pjdlog_debug(2,
				    "ggate_recv: (%p) Received cancel from the kernel.",
				    hio);
				pjdlog_info("Received cancel from the kernel, exiting.");
			}
			pthread_exit(NULL);
		case ENOMEM:
			/*
			 * Buffer too small? Impossible, we allocate MAXPHYS
			 * bytes - request can't be bigger than that.
			 */
			/* FALLTHROUGH */
		case ENXIO:
		default:
			primary_exitx(EX_OSERR, "G_GATE_CMD_START failed: %s.",
			    strerror(error));
		}

		ncomp = 0;
		ncomps = HAST_NCOMPONENTS;

		for (ii = 0; ii < ncomps; ii++)
			hio->hio_errors[ii] = EINVAL;
		reqlog(LOG_DEBUG, 2, ggio,
		    "ggate_recv: (%p) Request received from the kernel: ",
		    hio);

		/*
		 * Inform all components about new write request.
		 * For read request prefer local component unless the given
		 * range is out-of-date, then use remote component.
		 */
		switch (ggio->gctl_cmd) {
		case BIO_READ:
			res->hr_stat_read++;
			ncomps = 1;
			mtx_lock(&metadata_lock);
			if (res->hr_syncsrc == HAST_SYNCSRC_UNDEF ||
			    res->hr_syncsrc == HAST_SYNCSRC_PRIMARY) {
				/*
				 * This range is up-to-date on local component,
				 * so handle request locally.
				 */
				 /* Local component is 0 for now. */
				ncomp = 0;
			} else /* if (res->hr_syncsrc ==
			    HAST_SYNCSRC_SECONDARY) */ {
				PJDLOG_ASSERT(res->hr_syncsrc ==
				    HAST_SYNCSRC_SECONDARY);
				/*
				 * This range is out-of-date on local component,
				 * so send request to the remote node.
				 */
				 /* Remote component is 1 for now. */
				ncomp = 1;
			}
			mtx_unlock(&metadata_lock);
			break;
		case BIO_WRITE:
			res->hr_stat_write++;
			if (res->hr_resuid == 0 &&
			    res->hr_primary_localcnt == 0) {
				/* This is first write. */
				res->hr_primary_localcnt = 1;
			}
			for (;;) {
				mtx_lock(&range_lock);
				if (rangelock_islocked(range_sync,
				    ggio->gctl_offset, ggio->gctl_length)) {
					pjdlog_debug(2,
					    "regular: Range offset=%jd length=%zu locked.",
					    (intmax_t)ggio->gctl_offset,
					    (size_t)ggio->gctl_length);
					range_regular_wait = true;
					cv_wait(&range_regular_cond, &range_lock);
					range_regular_wait = false;
					mtx_unlock(&range_lock);
					continue;
				}
				if (rangelock_add(range_regular,
				    ggio->gctl_offset, ggio->gctl_length) == -1) {
					mtx_unlock(&range_lock);
					pjdlog_debug(2,
					    "regular: Range offset=%jd length=%zu is already locked, waiting.",
					    (intmax_t)ggio->gctl_offset,
					    (size_t)ggio->gctl_length);
					sleep(1);
					continue;
				}
				mtx_unlock(&range_lock);
				break;
			}
			mtx_lock(&res->hr_amp_lock);
			if (activemap_write_start(res->hr_amp,
			    ggio->gctl_offset, ggio->gctl_length)) {
				res->hr_stat_activemap_update++;
				(void)hast_activemap_flush(res);
			} else {
				mtx_unlock(&res->hr_amp_lock);
			}
			if (ISMEMSYNC(hio)) {
				hio->hio_memsyncacked = false;
				refcnt_init(&hio->hio_writecount, ncomps);
			}
			break;
		case BIO_DELETE:
			res->hr_stat_delete++;
			break;
		case BIO_FLUSH:
			res->hr_stat_flush++;
			break;
		}
		pjdlog_debug(2,
		    "ggate_recv: (%p) Moving request to the send queues.", hio);
		refcnt_init(&hio->hio_countdown, ncomps);
		for (ii = ncomp; ii < ncomps; ii++)
			QUEUE_INSERT1(hio, send, ii);
	}
	/* NOTREACHED */
	return (NULL);
}

/*
 * Thread reads from or writes to local component.
 * If local read fails, it redirects it to remote_send thread.
 */
static void *
local_send_thread(void *arg)
{
	struct hast_resource *res = arg;
	struct g_gate_ctl_io *ggio;
	struct hio *hio;
	unsigned int ncomp, rncomp;
	ssize_t ret;

	/* Local component is 0 for now. */
	ncomp = 0;
	/* Remote component is 1 for now. */
	rncomp = 1;

	for (;;) {
		pjdlog_debug(2, "local_send: Taking request.");
		QUEUE_TAKE1(hio, send, ncomp, 0);
		pjdlog_debug(2, "local_send: (%p) Got request.", hio);
		ggio = &hio->hio_ggio;
		switch (ggio->gctl_cmd) {
		case BIO_READ:
			ret = pread(res->hr_localfd, ggio->gctl_data,
			    ggio->gctl_length,
			    ggio->gctl_offset + res->hr_localoff);
			if (ret == ggio->gctl_length)
				hio->hio_errors[ncomp] = 0;
			else if (!ISSYNCREQ(hio)) {
				/*
				 * If READ failed, try to read from remote node.
				 */
				if (ret == -1) {
					reqlog(LOG_WARNING, 0, ggio,
					    "Local request failed (%s), trying remote node. ",
					    strerror(errno));
				} else if (ret != ggio->gctl_length) {
					reqlog(LOG_WARNING, 0, ggio,
					    "Local request failed (%zd != %jd), trying remote node. ",
					    ret, (intmax_t)ggio->gctl_length);
				}
				QUEUE_INSERT1(hio, send, rncomp);
				continue;
			}
			break;
		case BIO_WRITE:
			ret = pwrite(res->hr_localfd, ggio->gctl_data,
			    ggio->gctl_length,
			    ggio->gctl_offset + res->hr_localoff);
			if (ret == -1) {
				hio->hio_errors[ncomp] = errno;
				reqlog(LOG_WARNING, 0, ggio,
				    "Local request failed (%s): ",
				    strerror(errno));
			} else if (ret != ggio->gctl_length) {
				hio->hio_errors[ncomp] = EIO;
				reqlog(LOG_WARNING, 0, ggio,
				    "Local request failed (%zd != %jd): ",
				    ret, (intmax_t)ggio->gctl_length);
			} else {
				hio->hio_errors[ncomp] = 0;
				if (ISASYNC(hio)) {
					ggio->gctl_error = 0;
					write_complete(res, hio);
				}
			}
			break;
		case BIO_DELETE:
			ret = g_delete(res->hr_localfd,
			    ggio->gctl_offset + res->hr_localoff,
			    ggio->gctl_length);
			if (ret == -1) {
				hio->hio_errors[ncomp] = errno;
				reqlog(LOG_WARNING, 0, ggio,
				    "Local request failed (%s): ",
				    strerror(errno));
			} else {
				hio->hio_errors[ncomp] = 0;
			}
			break;
		case BIO_FLUSH:
			if (!res->hr_localflush) {
				ret = -1;
				errno = EOPNOTSUPP;
				break;
			}
			ret = g_flush(res->hr_localfd);
			if (ret == -1) {
				if (errno == EOPNOTSUPP)
					res->hr_localflush = false;
				hio->hio_errors[ncomp] = errno;
				reqlog(LOG_WARNING, 0, ggio,
				    "Local request failed (%s): ",
				    strerror(errno));
			} else {
				hio->hio_errors[ncomp] = 0;
			}
			break;
		}
		if (ISMEMSYNCWRITE(hio)) {
			if (refcnt_release(&hio->hio_writecount) == 0) {
				write_complete(res, hio);
			}
		}
		if (refcnt_release(&hio->hio_countdown) > 0)
			continue;
		if (ISSYNCREQ(hio)) {
			mtx_lock(&sync_lock);
			SYNCREQDONE(hio);
			mtx_unlock(&sync_lock);
			cv_signal(&sync_cond);
		} else {
			pjdlog_debug(2,
			    "local_send: (%p) Moving request to the done queue.",
			    hio);
			QUEUE_INSERT2(hio, done);
		}
	}
	/* NOTREACHED */
	return (NULL);
}

static void
keepalive_send(struct hast_resource *res, unsigned int ncomp)
{
	struct nv *nv;

	rw_rlock(&hio_remote_lock[ncomp]);

	if (!ISCONNECTED(res, ncomp)) {
		rw_unlock(&hio_remote_lock[ncomp]);
		return;
	}

	PJDLOG_ASSERT(res->hr_remotein != NULL);
	PJDLOG_ASSERT(res->hr_remoteout != NULL);

	nv = nv_alloc();
	nv_add_uint8(nv, HIO_KEEPALIVE, "cmd");
	if (nv_error(nv) != 0) {
		rw_unlock(&hio_remote_lock[ncomp]);
		nv_free(nv);
		pjdlog_debug(1,
		    "keepalive_send: Unable to prepare header to send.");
		return;
	}
	if (hast_proto_send(res, res->hr_remoteout, nv, NULL, 0) == -1) {
		rw_unlock(&hio_remote_lock[ncomp]);
		pjdlog_common(LOG_DEBUG, 1, errno,
		    "keepalive_send: Unable to send request");
		nv_free(nv);
		remote_close(res, ncomp);
		return;
	}

	rw_unlock(&hio_remote_lock[ncomp]);
	nv_free(nv);
	pjdlog_debug(2, "keepalive_send: Request sent.");
}

/*
 * Thread sends request to secondary node.
 */
static void *
remote_send_thread(void *arg)
{
	struct hast_resource *res = arg;
	struct g_gate_ctl_io *ggio;
	time_t lastcheck, now;
	struct hio *hio;
	struct nv *nv;
	unsigned int ncomp;
	bool wakeup;
	uint64_t offset, length;
	uint8_t cmd;
	void *data;

	/* Remote component is 1 for now. */
	ncomp = 1;
	lastcheck = time(NULL);

	for (;;) {
		pjdlog_debug(2, "remote_send: Taking request.");
		QUEUE_TAKE1(hio, send, ncomp, HAST_KEEPALIVE);
		if (hio == NULL) {
			now = time(NULL);
			if (lastcheck + HAST_KEEPALIVE <= now) {
				keepalive_send(res, ncomp);
				lastcheck = now;
			}
			continue;
		}
		pjdlog_debug(2, "remote_send: (%p) Got request.", hio);
		ggio = &hio->hio_ggio;
		switch (ggio->gctl_cmd) {
		case BIO_READ:
			cmd = HIO_READ;
			data = NULL;
			offset = ggio->gctl_offset;
			length = ggio->gctl_length;
			break;
		case BIO_WRITE:
			cmd = HIO_WRITE;
			data = ggio->gctl_data;
			offset = ggio->gctl_offset;
			length = ggio->gctl_length;
			break;
		case BIO_DELETE:
			cmd = HIO_DELETE;
			data = NULL;
			offset = ggio->gctl_offset;
			length = ggio->gctl_length;
			break;
		case BIO_FLUSH:
			cmd = HIO_FLUSH;
			data = NULL;
			offset = 0;
			length = 0;
			break;
		default:
			PJDLOG_ABORT("invalid condition");
		}
		nv = nv_alloc();
		nv_add_uint8(nv, cmd, "cmd");
		nv_add_uint64(nv, (uint64_t)ggio->gctl_seq, "seq");
		nv_add_uint64(nv, offset, "offset");
		nv_add_uint64(nv, length, "length");
		if (ISMEMSYNCWRITE(hio))
			nv_add_uint8(nv, 1, "memsync");
		if (nv_error(nv) != 0) {
			hio->hio_errors[ncomp] = nv_error(nv);
			pjdlog_debug(2,
			    "remote_send: (%p) Unable to prepare header to send.",
			    hio);
			reqlog(LOG_ERR, 0, ggio,
			    "Unable to prepare header to send (%s): ",
			    strerror(nv_error(nv)));
			/* Move failed request immediately to the done queue. */
			goto done_queue;
		}
		/*
		 * Protect connection from disappearing.
		 */
		rw_rlock(&hio_remote_lock[ncomp]);
		if (!ISCONNECTED(res, ncomp)) {
			rw_unlock(&hio_remote_lock[ncomp]);
			hio->hio_errors[ncomp] = ENOTCONN;
			goto done_queue;
		}
		/*
		 * Move the request to recv queue before sending it, because
		 * in different order we can get reply before we move request
		 * to recv queue.
		 */
		pjdlog_debug(2,
		    "remote_send: (%p) Moving request to the recv queue.",
		    hio);
		mtx_lock(&hio_recv_list_lock[ncomp]);
		wakeup = TAILQ_EMPTY(&hio_recv_list[ncomp]);
		TAILQ_INSERT_TAIL(&hio_recv_list[ncomp], hio, hio_next[ncomp]);
		hio_recv_list_size[ncomp]++;
		mtx_unlock(&hio_recv_list_lock[ncomp]);
		if (hast_proto_send(res, res->hr_remoteout, nv, data,
		    data != NULL ? length : 0) == -1) {
			hio->hio_errors[ncomp] = errno;
			rw_unlock(&hio_remote_lock[ncomp]);
			pjdlog_debug(2,
			    "remote_send: (%p) Unable to send request.", hio);
			reqlog(LOG_ERR, 0, ggio,
			    "Unable to send request (%s): ",
			    strerror(hio->hio_errors[ncomp]));
			remote_close(res, ncomp);
		} else {
			rw_unlock(&hio_remote_lock[ncomp]);
		}
		nv_free(nv);
		if (wakeup)
			cv_signal(&hio_recv_list_cond[ncomp]);
		continue;
done_queue:
		nv_free(nv);
		if (ISSYNCREQ(hio)) {
			if (refcnt_release(&hio->hio_countdown) > 0)
				continue;
			mtx_lock(&sync_lock);
			SYNCREQDONE(hio);
			mtx_unlock(&sync_lock);
			cv_signal(&sync_cond);
			continue;
		}
		if (ggio->gctl_cmd == BIO_WRITE) {
			mtx_lock(&res->hr_amp_lock);
			if (activemap_need_sync(res->hr_amp, ggio->gctl_offset,
			    ggio->gctl_length)) {
				(void)hast_activemap_flush(res);
			} else {
				mtx_unlock(&res->hr_amp_lock);
			}
			if (ISMEMSYNCWRITE(hio)) {
				if (refcnt_release(&hio->hio_writecount) == 0) {
					if (hio->hio_errors[0] == 0)
						write_complete(res, hio);
				}
			}
		}
		if (refcnt_release(&hio->hio_countdown) > 0)
			continue;
		pjdlog_debug(2,
		    "remote_send: (%p) Moving request to the done queue.",
		    hio);
		QUEUE_INSERT2(hio, done);
	}
	/* NOTREACHED */
	return (NULL);
}

/*
 * Thread receives answer from secondary node and passes it to ggate_send
 * thread.
 */
static void *
remote_recv_thread(void *arg)
{
	struct hast_resource *res = arg;
	struct g_gate_ctl_io *ggio;
	struct hio *hio;
	struct nv *nv;
	unsigned int ncomp;
	uint64_t seq;
	bool memsyncack;
	int error;

	/* Remote component is 1 for now. */
	ncomp = 1;

	for (;;) {
		/* Wait until there is anything to receive. */
		mtx_lock(&hio_recv_list_lock[ncomp]);
		while (TAILQ_EMPTY(&hio_recv_list[ncomp])) {
			pjdlog_debug(2, "remote_recv: No requests, waiting.");
			cv_wait(&hio_recv_list_cond[ncomp],
			    &hio_recv_list_lock[ncomp]);
		}
		mtx_unlock(&hio_recv_list_lock[ncomp]);

		memsyncack = false;

		rw_rlock(&hio_remote_lock[ncomp]);
		if (!ISCONNECTED(res, ncomp)) {
			rw_unlock(&hio_remote_lock[ncomp]);
			/*
			 * Connection is dead, so move all pending requests to
			 * the done queue (one-by-one).
			 */
			mtx_lock(&hio_recv_list_lock[ncomp]);
			hio = TAILQ_FIRST(&hio_recv_list[ncomp]);
			PJDLOG_ASSERT(hio != NULL);
			TAILQ_REMOVE(&hio_recv_list[ncomp], hio,
			    hio_next[ncomp]);
			hio_recv_list_size[ncomp]--;
			mtx_unlock(&hio_recv_list_lock[ncomp]);
			hio->hio_errors[ncomp] = ENOTCONN;
			goto done_queue;
		}
		if (hast_proto_recv_hdr(res->hr_remotein, &nv) == -1) {
			pjdlog_errno(LOG_ERR,
			    "Unable to receive reply header");
			rw_unlock(&hio_remote_lock[ncomp]);
			remote_close(res, ncomp);
			continue;
		}
		rw_unlock(&hio_remote_lock[ncomp]);
		seq = nv_get_uint64(nv, "seq");
		if (seq == 0) {
			pjdlog_error("Header contains no 'seq' field.");
			nv_free(nv);
			continue;
		}
		memsyncack = nv_exists(nv, "received");
		mtx_lock(&hio_recv_list_lock[ncomp]);
		TAILQ_FOREACH(hio, &hio_recv_list[ncomp], hio_next[ncomp]) {
			if (hio->hio_ggio.gctl_seq == seq) {
				TAILQ_REMOVE(&hio_recv_list[ncomp], hio,
				    hio_next[ncomp]);
				hio_recv_list_size[ncomp]--;
				break;
			}
		}
		mtx_unlock(&hio_recv_list_lock[ncomp]);
		if (hio == NULL) {
			pjdlog_error("Found no request matching received 'seq' field (%ju).",
			    (uintmax_t)seq);
			nv_free(nv);
			continue;
		}
		ggio = &hio->hio_ggio;
		error = nv_get_int16(nv, "error");
		if (error != 0) {
			/* Request failed on remote side. */
			hio->hio_errors[ncomp] = error;
			reqlog(LOG_WARNING, 0, ggio,
			    "Remote request failed (%s): ", strerror(error));
			nv_free(nv);
			goto done_queue;
		}
		switch (ggio->gctl_cmd) {
		case BIO_READ:
			rw_rlock(&hio_remote_lock[ncomp]);
			if (!ISCONNECTED(res, ncomp)) {
				rw_unlock(&hio_remote_lock[ncomp]);
				nv_free(nv);
				goto done_queue;
			}
			if (hast_proto_recv_data(res, res->hr_remotein, nv,
			    ggio->gctl_data, ggio->gctl_length) == -1) {
				hio->hio_errors[ncomp] = errno;
				pjdlog_errno(LOG_ERR,
				    "Unable to receive reply data");
				rw_unlock(&hio_remote_lock[ncomp]);
				nv_free(nv);
				remote_close(res, ncomp);
				goto done_queue;
			}
			rw_unlock(&hio_remote_lock[ncomp]);
			break;
		case BIO_WRITE:
		case BIO_DELETE:
		case BIO_FLUSH:
			break;
		default:
			PJDLOG_ABORT("invalid condition");
		}
		hio->hio_errors[ncomp] = 0;
		nv_free(nv);
done_queue:
		if (ISMEMSYNCWRITE(hio)) {
			if (!hio->hio_memsyncacked) {
				PJDLOG_ASSERT(memsyncack ||
				    hio->hio_errors[ncomp] != 0);
				/* Remote ack arrived. */
				if (refcnt_release(&hio->hio_writecount) == 0) {
					if (hio->hio_errors[0] == 0)
						write_complete(res, hio);
				}
				hio->hio_memsyncacked = true;
				if (hio->hio_errors[ncomp] == 0) {
					pjdlog_debug(2,
					    "remote_recv: (%p) Moving request "
					    "back to the recv queue.", hio);
					mtx_lock(&hio_recv_list_lock[ncomp]);
					TAILQ_INSERT_TAIL(&hio_recv_list[ncomp],
					    hio, hio_next[ncomp]);
					hio_recv_list_size[ncomp]++;
					mtx_unlock(&hio_recv_list_lock[ncomp]);
					continue;
				}
			} else {
				PJDLOG_ASSERT(!memsyncack);
				/* Remote final reply arrived. */
			}
		}
		if (refcnt_release(&hio->hio_countdown) > 0)
			continue;
		if (ISSYNCREQ(hio)) {
			mtx_lock(&sync_lock);
			SYNCREQDONE(hio);
			mtx_unlock(&sync_lock);
			cv_signal(&sync_cond);
		} else {
			pjdlog_debug(2,
			    "remote_recv: (%p) Moving request to the done queue.",
			    hio);
			QUEUE_INSERT2(hio, done);
		}
	}
	/* NOTREACHED */
	return (NULL);
}

/*
 * Thread sends answer to the kernel.
 */
static void *
ggate_send_thread(void *arg)
{
	struct hast_resource *res = arg;
	struct g_gate_ctl_io *ggio;
	struct hio *hio;
	unsigned int ii, ncomps;

	ncomps = HAST_NCOMPONENTS;

	for (;;) {
		pjdlog_debug(2, "ggate_send: Taking request.");
		QUEUE_TAKE2(hio, done);
		pjdlog_debug(2, "ggate_send: (%p) Got request.", hio);
		ggio = &hio->hio_ggio;
		for (ii = 0; ii < ncomps; ii++) {
			if (hio->hio_errors[ii] == 0) {
				/*
				 * One successful request is enough to declare
				 * success.
				 */
				ggio->gctl_error = 0;
				break;
			}
		}
		if (ii == ncomps) {
			/*
			 * None of the requests were successful.
			 * Use the error from local component except the
			 * case when we did only remote request.
			 */
			if (ggio->gctl_cmd == BIO_READ &&
			    res->hr_syncsrc == HAST_SYNCSRC_SECONDARY)
				ggio->gctl_error = hio->hio_errors[1];
			else
				ggio->gctl_error = hio->hio_errors[0];
		}
		if (ggio->gctl_error == 0 && ggio->gctl_cmd == BIO_WRITE) {
			mtx_lock(&res->hr_amp_lock);
			if (activemap_write_complete(res->hr_amp,
			    ggio->gctl_offset, ggio->gctl_length)) {
				res->hr_stat_activemap_update++;
				(void)hast_activemap_flush(res);
			} else {
				mtx_unlock(&res->hr_amp_lock);
			}
		}
		if (ggio->gctl_cmd == BIO_WRITE) {
			/*
			 * Unlock range we locked.
			 */
			mtx_lock(&range_lock);
			rangelock_del(range_regular, ggio->gctl_offset,
			    ggio->gctl_length);
			if (range_sync_wait)
				cv_signal(&range_sync_cond);
			mtx_unlock(&range_lock);
			if (!hio->hio_done)
				write_complete(res, hio);
		} else {
			if (ioctl(res->hr_ggatefd, G_GATE_CMD_DONE, ggio) == -1) {
				primary_exit(EX_OSERR,
				    "G_GATE_CMD_DONE failed");
			}
		}
		if (hio->hio_errors[0]) {
			switch (ggio->gctl_cmd) {
			case BIO_READ:
				res->hr_stat_read_error++;
				break;
			case BIO_WRITE:
				res->hr_stat_write_error++;
				break;
			case BIO_DELETE:
				res->hr_stat_delete_error++;
				break;
			case BIO_FLUSH:
				res->hr_stat_flush_error++;
				break;
			}
		}
		pjdlog_debug(2,
		    "ggate_send: (%p) Moving request to the free queue.", hio);
		QUEUE_INSERT2(hio, free);
	}
	/* NOTREACHED */
	return (NULL);
}

/*
 * Thread synchronize local and remote components.
 */
static void *
sync_thread(void *arg __unused)
{
	struct hast_resource *res = arg;
	struct hio *hio;
	struct g_gate_ctl_io *ggio;
	struct timeval tstart, tend, tdiff;
	unsigned int ii, ncomp, ncomps;
	off_t offset, length, synced;
	bool dorewind, directreads;
	int syncext;

	ncomps = HAST_NCOMPONENTS;
	dorewind = true;
	synced = 0;
	offset = -1;
	directreads = false;

	for (;;) {
		mtx_lock(&sync_lock);
		if (offset >= 0 && !sync_inprogress) {
			gettimeofday(&tend, NULL);
			timersub(&tend, &tstart, &tdiff);
			pjdlog_info("Synchronization interrupted after %#.0T. "
			    "%NB synchronized so far.", &tdiff,
			    (intmax_t)synced);
			event_send(res, EVENT_SYNCINTR);
		}
		while (!sync_inprogress) {
			dorewind = true;
			synced = 0;
			cv_wait(&sync_cond, &sync_lock);
		}
		mtx_unlock(&sync_lock);
		/*
		 * Obtain offset at which we should synchronize.
		 * Rewind synchronization if needed.
		 */
		mtx_lock(&res->hr_amp_lock);
		if (dorewind)
			activemap_sync_rewind(res->hr_amp);
		offset = activemap_sync_offset(res->hr_amp, &length, &syncext);
		if (syncext != -1) {
			/*
			 * We synchronized entire syncext extent, we can mark
			 * it as clean now.
			 */
			if (activemap_extent_complete(res->hr_amp, syncext))
				(void)hast_activemap_flush(res);
			else
				mtx_unlock(&res->hr_amp_lock);
		} else {
			mtx_unlock(&res->hr_amp_lock);
		}
		if (dorewind) {
			dorewind = false;
			if (offset == -1)
				pjdlog_info("Nodes are in sync.");
			else {
				pjdlog_info("Synchronization started. %NB to go.",
				    (intmax_t)(res->hr_extentsize *
				    activemap_ndirty(res->hr_amp)));
				event_send(res, EVENT_SYNCSTART);
				gettimeofday(&tstart, NULL);
			}
		}
		if (offset == -1) {
			sync_stop();
			pjdlog_debug(1, "Nothing to synchronize.");
			/*
			 * Synchronization complete, make both localcnt and
			 * remotecnt equal.
			 */
			ncomp = 1;
			rw_rlock(&hio_remote_lock[ncomp]);
			if (ISCONNECTED(res, ncomp)) {
				if (synced > 0) {
					int64_t bps;

					gettimeofday(&tend, NULL);
					timersub(&tend, &tstart, &tdiff);
					bps = (int64_t)((double)synced /
					    ((double)tdiff.tv_sec +
					    (double)tdiff.tv_usec / 1000000));
					pjdlog_info("Synchronization complete. "
					    "%NB synchronized in %#.0lT (%NB/sec).",
					    (intmax_t)synced, &tdiff,
					    (intmax_t)bps);
					event_send(res, EVENT_SYNCDONE);
				}
				mtx_lock(&metadata_lock);
				if (res->hr_syncsrc == HAST_SYNCSRC_SECONDARY)
					directreads = true;
				res->hr_syncsrc = HAST_SYNCSRC_UNDEF;
				res->hr_primary_localcnt =
				    res->hr_secondary_remotecnt;
				res->hr_primary_remotecnt =
				    res->hr_secondary_localcnt;
				pjdlog_debug(1,
				    "Setting localcnt to %ju and remotecnt to %ju.",
				    (uintmax_t)res->hr_primary_localcnt,
				    (uintmax_t)res->hr_primary_remotecnt);
				(void)metadata_write(res);
				mtx_unlock(&metadata_lock);
			}
			rw_unlock(&hio_remote_lock[ncomp]);
			if (directreads) {
				directreads = false;
				enable_direct_reads(res);
			}
			continue;
		}
		pjdlog_debug(2, "sync: Taking free request.");
		QUEUE_TAKE2(hio, free);
		pjdlog_debug(2, "sync: (%p) Got free request.", hio);
		/*
		 * Lock the range we are going to synchronize. We don't want
		 * race where someone writes between our read and write.
		 */
		for (;;) {
			mtx_lock(&range_lock);
			if (rangelock_islocked(range_regular, offset, length)) {
				pjdlog_debug(2,
				    "sync: Range offset=%jd length=%jd locked.",
				    (intmax_t)offset, (intmax_t)length);
				range_sync_wait = true;
				cv_wait(&range_sync_cond, &range_lock);
				range_sync_wait = false;
				mtx_unlock(&range_lock);
				continue;
			}
			if (rangelock_add(range_sync, offset, length) == -1) {
				mtx_unlock(&range_lock);
				pjdlog_debug(2,
				    "sync: Range offset=%jd length=%jd is already locked, waiting.",
				    (intmax_t)offset, (intmax_t)length);
				sleep(1);
				continue;
			}
			mtx_unlock(&range_lock);
			break;
		}
		/*
		 * First read the data from synchronization source.
		 */
		SYNCREQ(hio);
		ggio = &hio->hio_ggio;
		ggio->gctl_cmd = BIO_READ;
		ggio->gctl_offset = offset;
		ggio->gctl_length = length;
		ggio->gctl_error = 0;
		hio->hio_done = false;
		hio->hio_replication = res->hr_replication;
		for (ii = 0; ii < ncomps; ii++)
			hio->hio_errors[ii] = EINVAL;
		reqlog(LOG_DEBUG, 2, ggio, "sync: (%p) Sending sync request: ",
		    hio);
		pjdlog_debug(2, "sync: (%p) Moving request to the send queue.",
		    hio);
		mtx_lock(&metadata_lock);
		if (res->hr_syncsrc == HAST_SYNCSRC_PRIMARY) {
			/*
			 * This range is up-to-date on local component,
			 * so handle request locally.
			 */
			 /* Local component is 0 for now. */
			ncomp = 0;
		} else /* if (res->hr_syncsrc == HAST_SYNCSRC_SECONDARY) */ {
			PJDLOG_ASSERT(res->hr_syncsrc == HAST_SYNCSRC_SECONDARY);
			/*
			 * This range is out-of-date on local component,
			 * so send request to the remote node.
			 */
			 /* Remote component is 1 for now. */
			ncomp = 1;
		}
		mtx_unlock(&metadata_lock);
		refcnt_init(&hio->hio_countdown, 1);
		QUEUE_INSERT1(hio, send, ncomp);

		/*
		 * Let's wait for READ to finish.
		 */
		mtx_lock(&sync_lock);
		while (!ISSYNCREQDONE(hio))
			cv_wait(&sync_cond, &sync_lock);
		mtx_unlock(&sync_lock);

		if (hio->hio_errors[ncomp] != 0) {
			pjdlog_error("Unable to read synchronization data: %s.",
			    strerror(hio->hio_errors[ncomp]));
			goto free_queue;
		}

		/*
		 * We read the data from synchronization source, now write it
		 * to synchronization target.
		 */
		SYNCREQ(hio);
		ggio->gctl_cmd = BIO_WRITE;
		for (ii = 0; ii < ncomps; ii++)
			hio->hio_errors[ii] = EINVAL;
		reqlog(LOG_DEBUG, 2, ggio, "sync: (%p) Sending sync request: ",
		    hio);
		pjdlog_debug(2, "sync: (%p) Moving request to the send queue.",
		    hio);
		mtx_lock(&metadata_lock);
		if (res->hr_syncsrc == HAST_SYNCSRC_PRIMARY) {
			/*
			 * This range is up-to-date on local component,
			 * so we update remote component.
			 */
			 /* Remote component is 1 for now. */
			ncomp = 1;
		} else /* if (res->hr_syncsrc == HAST_SYNCSRC_SECONDARY) */ {
			PJDLOG_ASSERT(res->hr_syncsrc == HAST_SYNCSRC_SECONDARY);
			/*
			 * This range is out-of-date on local component,
			 * so we update it.
			 */
			 /* Local component is 0 for now. */
			ncomp = 0;
		}
		mtx_unlock(&metadata_lock);

		pjdlog_debug(2, "sync: (%p) Moving request to the send queue.",
		    hio);
		refcnt_init(&hio->hio_countdown, 1);
		QUEUE_INSERT1(hio, send, ncomp);

		/*
		 * Let's wait for WRITE to finish.
		 */
		mtx_lock(&sync_lock);
		while (!ISSYNCREQDONE(hio))
			cv_wait(&sync_cond, &sync_lock);
		mtx_unlock(&sync_lock);

		if (hio->hio_errors[ncomp] != 0) {
			pjdlog_error("Unable to write synchronization data: %s.",
			    strerror(hio->hio_errors[ncomp]));
			goto free_queue;
		}

		synced += length;
free_queue:
		mtx_lock(&range_lock);
		rangelock_del(range_sync, offset, length);
		if (range_regular_wait)
			cv_signal(&range_regular_cond);
		mtx_unlock(&range_lock);
		pjdlog_debug(2, "sync: (%p) Moving request to the free queue.",
		    hio);
		QUEUE_INSERT2(hio, free);
	}
	/* NOTREACHED */
	return (NULL);
}

void
primary_config_reload(struct hast_resource *res, struct nv *nv)
{
	unsigned int ii, ncomps;
	int modified, vint;
	const char *vstr;

	pjdlog_info("Reloading configuration...");

	PJDLOG_ASSERT(res->hr_role == HAST_ROLE_PRIMARY);
	PJDLOG_ASSERT(gres == res);
	nv_assert(nv, "remoteaddr");
	nv_assert(nv, "sourceaddr");
	nv_assert(nv, "replication");
	nv_assert(nv, "checksum");
	nv_assert(nv, "compression");
	nv_assert(nv, "timeout");
	nv_assert(nv, "exec");
	nv_assert(nv, "metaflush");

	ncomps = HAST_NCOMPONENTS;

#define MODIFIED_REMOTEADDR	0x01
#define MODIFIED_SOURCEADDR	0x02
#define MODIFIED_REPLICATION	0x04
#define MODIFIED_CHECKSUM	0x08
#define MODIFIED_COMPRESSION	0x10
#define MODIFIED_TIMEOUT	0x20
#define MODIFIED_EXEC		0x40
#define MODIFIED_METAFLUSH	0x80
	modified = 0;

	vstr = nv_get_string(nv, "remoteaddr");
	if (strcmp(gres->hr_remoteaddr, vstr) != 0) {
		/*
		 * Don't copy res->hr_remoteaddr to gres just yet.
		 * We want remote_close() to log disconnect from the old
		 * addresses, not from the new ones.
		 */
		modified |= MODIFIED_REMOTEADDR;
	}
	vstr = nv_get_string(nv, "sourceaddr");
	if (strcmp(gres->hr_sourceaddr, vstr) != 0) {
		strlcpy(gres->hr_sourceaddr, vstr, sizeof(gres->hr_sourceaddr));
		modified |= MODIFIED_SOURCEADDR;
	}
	vint = nv_get_int32(nv, "replication");
	if (gres->hr_replication != vint) {
		gres->hr_replication = vint;
		modified |= MODIFIED_REPLICATION;
	}
	vint = nv_get_int32(nv, "checksum");
	if (gres->hr_checksum != vint) {
		gres->hr_checksum = vint;
		modified |= MODIFIED_CHECKSUM;
	}
	vint = nv_get_int32(nv, "compression");
	if (gres->hr_compression != vint) {
		gres->hr_compression = vint;
		modified |= MODIFIED_COMPRESSION;
	}
	vint = nv_get_int32(nv, "timeout");
	if (gres->hr_timeout != vint) {
		gres->hr_timeout = vint;
		modified |= MODIFIED_TIMEOUT;
	}
	vstr = nv_get_string(nv, "exec");
	if (strcmp(gres->hr_exec, vstr) != 0) {
		strlcpy(gres->hr_exec, vstr, sizeof(gres->hr_exec));
		modified |= MODIFIED_EXEC;
	}
	vint = nv_get_int32(nv, "metaflush");
	if (gres->hr_metaflush != vint) {
		gres->hr_metaflush = vint;
		modified |= MODIFIED_METAFLUSH;
	}

	/*
	 * Change timeout for connected sockets.
	 * Don't bother if we need to reconnect.
	 */
	if ((modified & MODIFIED_TIMEOUT) != 0 &&
	    (modified & (MODIFIED_REMOTEADDR | MODIFIED_SOURCEADDR)) == 0) {
		for (ii = 0; ii < ncomps; ii++) {
			if (!ISREMOTE(ii))
				continue;
			rw_rlock(&hio_remote_lock[ii]);
			if (!ISCONNECTED(gres, ii)) {
				rw_unlock(&hio_remote_lock[ii]);
				continue;
			}
			rw_unlock(&hio_remote_lock[ii]);
			if (proto_timeout(gres->hr_remotein,
			    gres->hr_timeout) == -1) {
				pjdlog_errno(LOG_WARNING,
				    "Unable to set connection timeout");
			}
			if (proto_timeout(gres->hr_remoteout,
			    gres->hr_timeout) == -1) {
				pjdlog_errno(LOG_WARNING,
				    "Unable to set connection timeout");
			}
		}
	}
	if ((modified & (MODIFIED_REMOTEADDR | MODIFIED_SOURCEADDR)) != 0) {
		for (ii = 0; ii < ncomps; ii++) {
			if (!ISREMOTE(ii))
				continue;
			remote_close(gres, ii);
		}
		if (modified & MODIFIED_REMOTEADDR) {
			vstr = nv_get_string(nv, "remoteaddr");
			strlcpy(gres->hr_remoteaddr, vstr,
			    sizeof(gres->hr_remoteaddr));
		}
	}
#undef	MODIFIED_REMOTEADDR
#undef	MODIFIED_SOURCEADDR
#undef	MODIFIED_REPLICATION
#undef	MODIFIED_CHECKSUM
#undef	MODIFIED_COMPRESSION
#undef	MODIFIED_TIMEOUT
#undef	MODIFIED_EXEC
#undef	MODIFIED_METAFLUSH

	pjdlog_info("Configuration reloaded successfully.");
}

static void
guard_one(struct hast_resource *res, unsigned int ncomp)
{
	struct proto_conn *in, *out;

	if (!ISREMOTE(ncomp))
		return;

	rw_rlock(&hio_remote_lock[ncomp]);

	if (!real_remote(res)) {
		rw_unlock(&hio_remote_lock[ncomp]);
		return;
	}

	if (ISCONNECTED(res, ncomp)) {
		PJDLOG_ASSERT(res->hr_remotein != NULL);
		PJDLOG_ASSERT(res->hr_remoteout != NULL);
		rw_unlock(&hio_remote_lock[ncomp]);
		pjdlog_debug(2, "remote_guard: Connection to %s is ok.",
		    res->hr_remoteaddr);
		return;
	}

	PJDLOG_ASSERT(res->hr_remotein == NULL);
	PJDLOG_ASSERT(res->hr_remoteout == NULL);
	/*
	 * Upgrade the lock. It doesn't have to be atomic as no other thread
	 * can change connection status from disconnected to connected.
	 */
	rw_unlock(&hio_remote_lock[ncomp]);
	pjdlog_debug(2, "remote_guard: Reconnecting to %s.",
	    res->hr_remoteaddr);
	in = out = NULL;
	if (init_remote(res, &in, &out) == 0) {
		rw_wlock(&hio_remote_lock[ncomp]);
		PJDLOG_ASSERT(res->hr_remotein == NULL);
		PJDLOG_ASSERT(res->hr_remoteout == NULL);
		PJDLOG_ASSERT(in != NULL && out != NULL);
		res->hr_remotein = in;
		res->hr_remoteout = out;
		rw_unlock(&hio_remote_lock[ncomp]);
		pjdlog_info("Successfully reconnected to %s.",
		    res->hr_remoteaddr);
		sync_start();
	} else {
		/* Both connections should be NULL. */
		PJDLOG_ASSERT(res->hr_remotein == NULL);
		PJDLOG_ASSERT(res->hr_remoteout == NULL);
		PJDLOG_ASSERT(in == NULL && out == NULL);
		pjdlog_debug(2, "remote_guard: Reconnect to %s failed.",
		    res->hr_remoteaddr);
	}
}

/*
 * Thread guards remote connections and reconnects when needed, handles
 * signals, etc.
 */
static void *
guard_thread(void *arg)
{
	struct hast_resource *res = arg;
	unsigned int ii, ncomps;
	struct timespec timeout;
	time_t lastcheck, now;
	sigset_t mask;
	int signo;

	ncomps = HAST_NCOMPONENTS;
	lastcheck = time(NULL);

	PJDLOG_VERIFY(sigemptyset(&mask) == 0);
	PJDLOG_VERIFY(sigaddset(&mask, SIGINT) == 0);
	PJDLOG_VERIFY(sigaddset(&mask, SIGTERM) == 0);

	timeout.tv_sec = HAST_KEEPALIVE;
	timeout.tv_nsec = 0;
	signo = -1;

	for (;;) {
		switch (signo) {
		case SIGINT:
		case SIGTERM:
			sigexit_received = true;
			primary_exitx(EX_OK,
			    "Termination signal received, exiting.");
			break;
		default:
			break;
		}

		/*
		 * Don't check connections until we fully started,
		 * as we may still be looping, waiting for remote node
		 * to switch from primary to secondary.
		 */
		if (fullystarted) {
			pjdlog_debug(2, "remote_guard: Checking connections.");
			now = time(NULL);
			if (lastcheck + HAST_KEEPALIVE <= now) {
				for (ii = 0; ii < ncomps; ii++)
					guard_one(res, ii);
				lastcheck = now;
			}
		}
		signo = sigtimedwait(&mask, NULL, &timeout);
	}
	/* NOTREACHED */
	return (NULL);
}