Stuck at home?

Check our new online training!

Stuck at home?

All Bootlin training courses
are now available
through on-line seminars

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
/*
  drbd_int.h

  This file is part of DRBD by Philipp Reisner and Lars Ellenberg.

  Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
  Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
  Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.

  drbd is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2, or (at your option)
  any later version.

  drbd is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with drbd; see the file COPYING.  If not, write to
  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef _DRBD_INT_H
#define _DRBD_INT_H

#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/crypto.h>
#include <linux/ratelimit.h>
#include <linux/tcp.h>
#include <linux/mutex.h>
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/genhd.h>
#include <linux/idr.h>
#include <net/tcp.h>
#include <linux/lru_cache.h>
#include <linux/prefetch.h>
#include <linux/drbd_genl_api.h>
#include <linux/drbd.h>
#include "drbd_state.h"

#ifdef __CHECKER__
# define __protected_by(x)       __attribute__((require_context(x,1,999,"rdwr")))
# define __protected_read_by(x)  __attribute__((require_context(x,1,999,"read")))
# define __protected_write_by(x) __attribute__((require_context(x,1,999,"write")))
# define __must_hold(x)       __attribute__((context(x,1,1), require_context(x,1,999,"call")))
#else
# define __protected_by(x)
# define __protected_read_by(x)
# define __protected_write_by(x)
# define __must_hold(x)
#endif

#define __no_warn(lock, stmt) do { __acquire(lock); stmt; __release(lock); } while (0)

/* module parameter, defined in drbd_main.c */
extern unsigned int minor_count;
extern bool disable_sendpage;
extern bool allow_oos;

#ifdef CONFIG_DRBD_FAULT_INJECTION
extern int enable_faults;
extern int fault_rate;
extern int fault_devs;
#endif

extern char usermode_helper[];


/* I don't remember why XCPU ...
 * This is used to wake the asender,
 * and to interrupt sending the sending task
 * on disconnect.
 */
#define DRBD_SIG SIGXCPU

/* This is used to stop/restart our threads.
 * Cannot use SIGTERM nor SIGKILL, since these
 * are sent out by init on runlevel changes
 * I choose SIGHUP for now.
 */
#define DRBD_SIGKILL SIGHUP

#define ID_IN_SYNC      (4711ULL)
#define ID_OUT_OF_SYNC  (4712ULL)
#define ID_SYNCER (-1ULL)

#define UUID_NEW_BM_OFFSET ((u64)0x0001000000000000ULL)

struct drbd_conf;
struct drbd_tconn;


/* to shorten dev_warn(DEV, "msg"); and relatives statements */
#define DEV (disk_to_dev(mdev->vdisk))

#define conn_printk(LEVEL, TCONN, FMT, ARGS...) \
	printk(LEVEL "d-con %s: " FMT, TCONN->name , ## ARGS)
#define conn_alert(TCONN, FMT, ARGS...)  conn_printk(KERN_ALERT, TCONN, FMT, ## ARGS)
#define conn_crit(TCONN, FMT, ARGS...)   conn_printk(KERN_CRIT, TCONN, FMT, ## ARGS)
#define conn_err(TCONN, FMT, ARGS...)    conn_printk(KERN_ERR, TCONN, FMT, ## ARGS)
#define conn_warn(TCONN, FMT, ARGS...)   conn_printk(KERN_WARNING, TCONN, FMT, ## ARGS)
#define conn_notice(TCONN, FMT, ARGS...) conn_printk(KERN_NOTICE, TCONN, FMT, ## ARGS)
#define conn_info(TCONN, FMT, ARGS...)   conn_printk(KERN_INFO, TCONN, FMT, ## ARGS)
#define conn_dbg(TCONN, FMT, ARGS...)    conn_printk(KERN_DEBUG, TCONN, FMT, ## ARGS)

#define D_ASSERT(exp)	if (!(exp)) \
	 dev_err(DEV, "ASSERT( " #exp " ) in %s:%d\n", __FILE__, __LINE__)

/**
 * expect  -  Make an assertion
 *
 * Unlike the assert macro, this macro returns a boolean result.
 */
#define expect(exp) ({								\
		bool _bool = (exp);						\
		if (!_bool)							\
			dev_err(DEV, "ASSERTION %s FAILED in %s\n",		\
			        #exp, __func__);				\
		_bool;								\
		})

/* Defines to control fault insertion */
enum {
	DRBD_FAULT_MD_WR = 0,	/* meta data write */
	DRBD_FAULT_MD_RD = 1,	/*           read  */
	DRBD_FAULT_RS_WR = 2,	/* resync          */
	DRBD_FAULT_RS_RD = 3,
	DRBD_FAULT_DT_WR = 4,	/* data            */
	DRBD_FAULT_DT_RD = 5,
	DRBD_FAULT_DT_RA = 6,	/* data read ahead */
	DRBD_FAULT_BM_ALLOC = 7,	/* bitmap allocation */
	DRBD_FAULT_AL_EE = 8,	/* alloc ee */
	DRBD_FAULT_RECEIVE = 9, /* Changes some bytes upon receiving a [rs]data block */

	DRBD_FAULT_MAX,
};

extern unsigned int
_drbd_insert_fault(struct drbd_conf *mdev, unsigned int type);

static inline int
drbd_insert_fault(struct drbd_conf *mdev, unsigned int type) {
#ifdef CONFIG_DRBD_FAULT_INJECTION
	return fault_rate &&
		(enable_faults & (1<<type)) &&
		_drbd_insert_fault(mdev, type);
#else
	return 0;
#endif
}

/* integer division, round _UP_ to the next integer */
#define div_ceil(A, B) ((A)/(B) + ((A)%(B) ? 1 : 0))
/* usual integer division */
#define div_floor(A, B) ((A)/(B))

extern struct ratelimit_state drbd_ratelimit_state;
extern struct idr minors; /* RCU, updates: genl_lock() */
extern struct list_head drbd_tconns; /* RCU, updates: genl_lock() */

/* on the wire */
enum drbd_packet {
	/* receiver (data socket) */
	P_DATA		      = 0x00,
	P_DATA_REPLY	      = 0x01, /* Response to P_DATA_REQUEST */
	P_RS_DATA_REPLY	      = 0x02, /* Response to P_RS_DATA_REQUEST */
	P_BARRIER	      = 0x03,
	P_BITMAP	      = 0x04,
	P_BECOME_SYNC_TARGET  = 0x05,
	P_BECOME_SYNC_SOURCE  = 0x06,
	P_UNPLUG_REMOTE	      = 0x07, /* Used at various times to hint the peer */
	P_DATA_REQUEST	      = 0x08, /* Used to ask for a data block */
	P_RS_DATA_REQUEST     = 0x09, /* Used to ask for a data block for resync */
	P_SYNC_PARAM	      = 0x0a,
	P_PROTOCOL	      = 0x0b,
	P_UUIDS		      = 0x0c,
	P_SIZES		      = 0x0d,
	P_STATE		      = 0x0e,
	P_SYNC_UUID	      = 0x0f,
	P_AUTH_CHALLENGE      = 0x10,
	P_AUTH_RESPONSE	      = 0x11,
	P_STATE_CHG_REQ	      = 0x12,

	/* asender (meta socket */
	P_PING		      = 0x13,
	P_PING_ACK	      = 0x14,
	P_RECV_ACK	      = 0x15, /* Used in protocol B */
	P_WRITE_ACK	      = 0x16, /* Used in protocol C */
	P_RS_WRITE_ACK	      = 0x17, /* Is a P_WRITE_ACK, additionally call set_in_sync(). */
	P_SUPERSEDED	      = 0x18, /* Used in proto C, two-primaries conflict detection */
	P_NEG_ACK	      = 0x19, /* Sent if local disk is unusable */
	P_NEG_DREPLY	      = 0x1a, /* Local disk is broken... */
	P_NEG_RS_DREPLY	      = 0x1b, /* Local disk is broken... */
	P_BARRIER_ACK	      = 0x1c,
	P_STATE_CHG_REPLY     = 0x1d,

	/* "new" commands, no longer fitting into the ordering scheme above */

	P_OV_REQUEST	      = 0x1e, /* data socket */
	P_OV_REPLY	      = 0x1f,
	P_OV_RESULT	      = 0x20, /* meta socket */
	P_CSUM_RS_REQUEST     = 0x21, /* data socket */
	P_RS_IS_IN_SYNC	      = 0x22, /* meta socket */
	P_SYNC_PARAM89	      = 0x23, /* data socket, protocol version 89 replacement for P_SYNC_PARAM */
	P_COMPRESSED_BITMAP   = 0x24, /* compressed or otherwise encoded bitmap transfer */
	/* P_CKPT_FENCE_REQ      = 0x25, * currently reserved for protocol D */
	/* P_CKPT_DISABLE_REQ    = 0x26, * currently reserved for protocol D */
	P_DELAY_PROBE         = 0x27, /* is used on BOTH sockets */
	P_OUT_OF_SYNC         = 0x28, /* Mark as out of sync (Outrunning), data socket */
	P_RS_CANCEL           = 0x29, /* meta: Used to cancel RS_DATA_REQUEST packet by SyncSource */
	P_CONN_ST_CHG_REQ     = 0x2a, /* data sock: Connection wide state request */
	P_CONN_ST_CHG_REPLY   = 0x2b, /* meta sock: Connection side state req reply */
	P_RETRY_WRITE	      = 0x2c, /* Protocol C: retry conflicting write request */
	P_PROTOCOL_UPDATE     = 0x2d, /* data sock: is used in established connections */

	P_MAY_IGNORE	      = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
	P_MAX_OPT_CMD	      = 0x101,

	/* special command ids for handshake */

	P_INITIAL_META	      = 0xfff1, /* First Packet on the MetaSock */
	P_INITIAL_DATA	      = 0xfff2, /* First Packet on the Socket */

	P_CONNECTION_FEATURES = 0xfffe	/* FIXED for the next century! */
};

extern const char *cmdname(enum drbd_packet cmd);

/* for sending/receiving the bitmap,
 * possibly in some encoding scheme */
struct bm_xfer_ctx {
	/* "const"
	 * stores total bits and long words
	 * of the bitmap, so we don't need to
	 * call the accessor functions over and again. */
	unsigned long bm_bits;
	unsigned long bm_words;
	/* during xfer, current position within the bitmap */
	unsigned long bit_offset;
	unsigned long word_offset;

	/* statistics; index: (h->command == P_BITMAP) */
	unsigned packets[2];
	unsigned bytes[2];
};

extern void INFO_bm_xfer_stats(struct drbd_conf *mdev,
		const char *direction, struct bm_xfer_ctx *c);

static inline void bm_xfer_ctx_bit_to_word_offset(struct bm_xfer_ctx *c)
{
	/* word_offset counts "native long words" (32 or 64 bit),
	 * aligned at 64 bit.
	 * Encoded packet may end at an unaligned bit offset.
	 * In case a fallback clear text packet is transmitted in
	 * between, we adjust this offset back to the last 64bit
	 * aligned "native long word", which makes coding and decoding
	 * the plain text bitmap much more convenient.  */
#if BITS_PER_LONG == 64
	c->word_offset = c->bit_offset >> 6;
#elif BITS_PER_LONG == 32
	c->word_offset = c->bit_offset >> 5;
	c->word_offset &= ~(1UL);
#else
# error "unsupported BITS_PER_LONG"
#endif
}

#ifndef __packed
#define __packed __attribute__((packed))
#endif

/* This is the layout for a packet on the wire.
 * The byteorder is the network byte order.
 *     (except block_id and barrier fields.
 *	these are pointers to local structs
 *	and have no relevance for the partner,
 *	which just echoes them as received.)
 *
 * NOTE that the payload starts at a long aligned offset,
 * regardless of 32 or 64 bit arch!
 */
struct p_header80 {
	u32	  magic;
	u16	  command;
	u16	  length;	/* bytes of data after this header */
} __packed;

/* Header for big packets, Used for data packets exceeding 64kB */
struct p_header95 {
	u16	  magic;	/* use DRBD_MAGIC_BIG here */
	u16	  command;
	u32	  length;
} __packed;

struct p_header100 {
	u32	  magic;
	u16	  volume;
	u16	  command;
	u32	  length;
	u32	  pad;
} __packed;

extern unsigned int drbd_header_size(struct drbd_tconn *tconn);

/* these defines must not be changed without changing the protocol version */
#define DP_HARDBARRIER	      1 /* depricated */
#define DP_RW_SYNC	      2 /* equals REQ_SYNC    */
#define DP_MAY_SET_IN_SYNC    4
#define DP_UNPLUG             8 /* not used anymore   */
#define DP_FUA               16 /* equals REQ_FUA     */
#define DP_FLUSH             32 /* equals REQ_FLUSH   */
#define DP_DISCARD           64 /* equals REQ_DISCARD */
#define DP_SEND_RECEIVE_ACK 128 /* This is a proto B write request */
#define DP_SEND_WRITE_ACK   256 /* This is a proto C write request */

struct p_data {
	u64	    sector;    /* 64 bits sector number */
	u64	    block_id;  /* to identify the request in protocol B&C */
	u32	    seq_num;
	u32	    dp_flags;
} __packed;

/*
 * commands which share a struct:
 *  p_block_ack:
 *   P_RECV_ACK (proto B), P_WRITE_ACK (proto C),
 *   P_SUPERSEDED (proto C, two-primaries conflict detection)
 *  p_block_req:
 *   P_DATA_REQUEST, P_RS_DATA_REQUEST
 */
struct p_block_ack {
	u64	    sector;
	u64	    block_id;
	u32	    blksize;
	u32	    seq_num;
} __packed;

struct p_block_req {
	u64 sector;
	u64 block_id;
	u32 blksize;
	u32 pad;	/* to multiple of 8 Byte */
} __packed;

/*
 * commands with their own struct for additional fields:
 *   P_CONNECTION_FEATURES
 *   P_BARRIER
 *   P_BARRIER_ACK
 *   P_SYNC_PARAM
 *   ReportParams
 */

struct p_connection_features {
	u32 protocol_min;
	u32 feature_flags;
	u32 protocol_max;

	/* should be more than enough for future enhancements
	 * for now, feature_flags and the reserved array shall be zero.
	 */

	u32 _pad;
	u64 reserved[7];
} __packed;

struct p_barrier {
	u32 barrier;	/* barrier number _handle_ only */
	u32 pad;	/* to multiple of 8 Byte */
} __packed;

struct p_barrier_ack {
	u32 barrier;
	u32 set_size;
} __packed;

struct p_rs_param {
	u32 resync_rate;

	      /* Since protocol version 88 and higher. */
	char verify_alg[0];
} __packed;

struct p_rs_param_89 {
	u32 resync_rate;
        /* protocol version 89: */
	char verify_alg[SHARED_SECRET_MAX];
	char csums_alg[SHARED_SECRET_MAX];
} __packed;

struct p_rs_param_95 {
	u32 resync_rate;
	char verify_alg[SHARED_SECRET_MAX];
	char csums_alg[SHARED_SECRET_MAX];
	u32 c_plan_ahead;
	u32 c_delay_target;
	u32 c_fill_target;
	u32 c_max_rate;
} __packed;

enum drbd_conn_flags {
	CF_DISCARD_MY_DATA = 1,
	CF_DRY_RUN = 2,
};

struct p_protocol {
	u32 protocol;
	u32 after_sb_0p;
	u32 after_sb_1p;
	u32 after_sb_2p;
	u32 conn_flags;
	u32 two_primaries;

              /* Since protocol version 87 and higher. */
	char integrity_alg[0];

} __packed;

struct p_uuids {
	u64 uuid[UI_EXTENDED_SIZE];
} __packed;

struct p_rs_uuid {
	u64	    uuid;
} __packed;

struct p_sizes {
	u64	    d_size;  /* size of disk */
	u64	    u_size;  /* user requested size */
	u64	    c_size;  /* current exported size */
	u32	    max_bio_size;  /* Maximal size of a BIO */
	u16	    queue_order_type;  /* not yet implemented in DRBD*/
	u16	    dds_flags; /* use enum dds_flags here. */
} __packed;

struct p_state {
	u32	    state;
} __packed;

struct p_req_state {
	u32	    mask;
	u32	    val;
} __packed;

struct p_req_state_reply {
	u32	    retcode;
} __packed;

struct p_drbd06_param {
	u64	  size;
	u32	  state;
	u32	  blksize;
	u32	  protocol;
	u32	  version;
	u32	  gen_cnt[5];
	u32	  bit_map_gen[5];
} __packed;

struct p_block_desc {
	u64 sector;
	u32 blksize;
	u32 pad;	/* to multiple of 8 Byte */
} __packed;

/* Valid values for the encoding field.
 * Bump proto version when changing this. */
enum drbd_bitmap_code {
	/* RLE_VLI_Bytes = 0,
	 * and other bit variants had been defined during
	 * algorithm evaluation. */
	RLE_VLI_Bits = 2,
};

struct p_compressed_bm {
	/* (encoding & 0x0f): actual encoding, see enum drbd_bitmap_code
	 * (encoding & 0x80): polarity (set/unset) of first runlength
	 * ((encoding >> 4) & 0x07): pad_bits, number of trailing zero bits
	 * used to pad up to head.length bytes
	 */
	u8 encoding;

	u8 code[0];
} __packed;

struct p_delay_probe93 {
	u32     seq_num; /* sequence number to match the two probe packets */
	u32     offset;  /* usecs the probe got sent after the reference time point */
} __packed;

/*
 * Bitmap packets need to fit within a single page on the sender and receiver,
 * so we are limited to 4 KiB (and not to PAGE_SIZE, which can be bigger).
 */
#define DRBD_SOCKET_BUFFER_SIZE 4096

/**********************************************************************/
enum drbd_thread_state {
	NONE,
	RUNNING,
	EXITING,
	RESTARTING
};

struct drbd_thread {
	spinlock_t t_lock;
	struct task_struct *task;
	struct completion stop;
	enum drbd_thread_state t_state;
	int (*function) (struct drbd_thread *);
	struct drbd_tconn *tconn;
	int reset_cpu_mask;
	char name[9];
};

static inline enum drbd_thread_state get_t_state(struct drbd_thread *thi)
{
	/* THINK testing the t_state seems to be uncritical in all cases
	 * (but thread_{start,stop}), so we can read it *without* the lock.
	 *	--lge */

	smp_rmb();
	return thi->t_state;
}

struct drbd_work {
	struct list_head list;
	int (*cb)(struct drbd_work *, int cancel);
	union {
		struct drbd_conf *mdev;
		struct drbd_tconn *tconn;
	};
};

#include "drbd_interval.h"

extern int drbd_wait_misc(struct drbd_conf *, struct drbd_interval *);

struct drbd_request {
	struct drbd_work w;

	/* if local IO is not allowed, will be NULL.
	 * if local IO _is_ allowed, holds the locally submitted bio clone,
	 * or, after local IO completion, the ERR_PTR(error).
	 * see drbd_request_endio(). */
	struct bio *private_bio;

	struct drbd_interval i;

	/* epoch: used to check on "completion" whether this req was in
	 * the current epoch, and we therefore have to close it,
	 * causing a p_barrier packet to be send, starting a new epoch.
	 *
	 * This corresponds to "barrier" in struct p_barrier[_ack],
	 * and to "barrier_nr" in struct drbd_epoch (and various
	 * comments/function parameters/local variable names).
	 */
	unsigned int epoch;

	struct list_head tl_requests; /* ring list in the transfer log */
	struct bio *master_bio;       /* master bio pointer */
	unsigned long start_time;

	/* once it hits 0, we may complete the master_bio */
	atomic_t completion_ref;
	/* once it hits 0, we may destroy this drbd_request object */
	struct kref kref;

	unsigned rq_state; /* see comments above _req_mod() */
};

struct drbd_epoch {
	struct drbd_tconn *tconn;
	struct list_head list;
	unsigned int barrier_nr;
	atomic_t epoch_size; /* increased on every request added. */
	atomic_t active;     /* increased on every req. added, and dec on every finished. */
	unsigned long flags;
};

/* drbd_epoch flag bits */
enum {
	DE_HAVE_BARRIER_NUMBER,
};

enum epoch_event {
	EV_PUT,
	EV_GOT_BARRIER_NR,
	EV_BECAME_LAST,
	EV_CLEANUP = 32, /* used as flag */
};

struct drbd_wq_barrier {
	struct drbd_work w;
	struct completion done;
};

struct digest_info {
	int digest_size;
	void *digest;
};

struct drbd_peer_request {
	struct drbd_work w;
	struct drbd_epoch *epoch; /* for writes */
	struct page *pages;
	atomic_t pending_bios;
	struct drbd_interval i;
	/* see comments on ee flag bits below */
	unsigned long flags;
	union {
		u64 block_id;
		struct digest_info *digest;
	};
};

/* ee flag bits.
 * While corresponding bios are in flight, the only modification will be
 * set_bit WAS_ERROR, which has to be atomic.
 * If no bios are in flight yet, or all have been completed,
 * non-atomic modification to ee->flags is ok.
 */
enum {
	__EE_CALL_AL_COMPLETE_IO,
	__EE_MAY_SET_IN_SYNC,

	/* In case a barrier failed,
	 * we need to resubmit without the barrier flag. */
	__EE_RESUBMITTED,

	/* we may have several bios per peer request.
	 * if any of those fail, we set this flag atomically
	 * from the endio callback */
	__EE_WAS_ERROR,

	/* This ee has a pointer to a digest instead of a block id */
	__EE_HAS_DIGEST,

	/* Conflicting local requests need to be restarted after this request */
	__EE_RESTART_REQUESTS,

	/* The peer wants a write ACK for this (wire proto C) */
	__EE_SEND_WRITE_ACK,

	/* Is set when net_conf had two_primaries set while creating this peer_req */
	__EE_IN_INTERVAL_TREE,
};
#define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
#define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
#define	EE_RESUBMITTED         (1<<__EE_RESUBMITTED)
#define EE_WAS_ERROR           (1<<__EE_WAS_ERROR)
#define EE_HAS_DIGEST          (1<<__EE_HAS_DIGEST)
#define EE_RESTART_REQUESTS	(1<<__EE_RESTART_REQUESTS)
#define EE_SEND_WRITE_ACK	(1<<__EE_SEND_WRITE_ACK)
#define EE_IN_INTERVAL_TREE	(1<<__EE_IN_INTERVAL_TREE)

/* flag bits per mdev */
enum {
	UNPLUG_REMOTE,		/* sending a "UnplugRemote" could help */
	MD_DIRTY,		/* current uuids and flags not yet on disk */
	USE_DEGR_WFC_T,		/* degr-wfc-timeout instead of wfc-timeout. */
	CL_ST_CHG_SUCCESS,
	CL_ST_CHG_FAIL,
	CRASHED_PRIMARY,	/* This node was a crashed primary.
				 * Gets cleared when the state.conn
				 * goes into C_CONNECTED state. */
	CONSIDER_RESYNC,

	MD_NO_FUA,		/* Users wants us to not use FUA/FLUSH on meta data dev */
	SUSPEND_IO,		/* suspend application io */
	BITMAP_IO,		/* suspend application io;
				   once no more io in flight, start bitmap io */
	BITMAP_IO_QUEUED,       /* Started bitmap IO */
	GO_DISKLESS,		/* Disk is being detached, on io-error or admin request. */
	WAS_IO_ERROR,		/* Local disk failed, returned IO error */
	WAS_READ_ERROR,		/* Local disk READ failed (set additionally to the above) */
	FORCE_DETACH,		/* Force-detach from local disk, aborting any pending local IO */
	RESYNC_AFTER_NEG,       /* Resync after online grow after the attach&negotiate finished. */
	RESIZE_PENDING,		/* Size change detected locally, waiting for the response from
				 * the peer, if it changed there as well. */
	NEW_CUR_UUID,		/* Create new current UUID when thawing IO */
	AL_SUSPENDED,		/* Activity logging is currently suspended. */
	AHEAD_TO_SYNC_SOURCE,   /* Ahead -> SyncSource queued */
	B_RS_H_DONE,		/* Before resync handler done (already executed) */
	DISCARD_MY_DATA,	/* discard_my_data flag per volume */
	READ_BALANCE_RR,
};

struct drbd_bitmap; /* opaque for drbd_conf */

/* definition of bits in bm_flags to be used in drbd_bm_lock
 * and drbd_bitmap_io and friends. */
enum bm_flag {
	/* do we need to kfree, or vfree bm_pages? */
	BM_P_VMALLOCED = 0x10000, /* internal use only, will be masked out */

	/* currently locked for bulk operation */
	BM_LOCKED_MASK = 0xf,

	/* in detail, that is: */
	BM_DONT_CLEAR = 0x1,
	BM_DONT_SET   = 0x2,
	BM_DONT_TEST  = 0x4,

	/* so we can mark it locked for bulk operation,
	 * and still allow all non-bulk operations */
	BM_IS_LOCKED  = 0x8,

	/* (test bit, count bit) allowed (common case) */
	BM_LOCKED_TEST_ALLOWED = BM_DONT_CLEAR | BM_DONT_SET | BM_IS_LOCKED,

	/* testing bits, as well as setting new bits allowed, but clearing bits
	 * would be unexpected.  Used during bitmap receive.  Setting new bits
	 * requires sending of "out-of-sync" information, though. */
	BM_LOCKED_SET_ALLOWED = BM_DONT_CLEAR | BM_IS_LOCKED,

	/* for drbd_bm_write_copy_pages, everything is allowed,
	 * only concurrent bulk operations are locked out. */
	BM_LOCKED_CHANGE_ALLOWED = BM_IS_LOCKED,
};

struct drbd_work_queue {
	struct list_head q;
	spinlock_t q_lock;  /* to protect the list. */
	wait_queue_head_t q_wait;
};

struct drbd_socket {
	struct mutex mutex;
	struct socket    *socket;
	/* this way we get our
	 * send/receive buffers off the stack */
	void *sbuf;
	void *rbuf;
};

struct drbd_md {
	u64 md_offset;		/* sector offset to 'super' block */

	u64 la_size_sect;	/* last agreed size, unit sectors */
	spinlock_t uuid_lock;
	u64 uuid[UI_SIZE];
	u64 device_uuid;
	u32 flags;
	u32 md_size_sect;

	s32 al_offset;	/* signed relative sector offset to activity log */
	s32 bm_offset;	/* signed relative sector offset to bitmap */

	/* cached value of bdev->disk_conf->meta_dev_idx (see below) */
	s32 meta_dev_idx;

	/* see al_tr_number_to_on_disk_sector() */
	u32 al_stripes;
	u32 al_stripe_size_4k;
	u32 al_size_4k; /* cached product of the above */
};

struct drbd_backing_dev {
	struct block_device *backing_bdev;
	struct block_device *md_bdev;
	struct drbd_md md;
	struct disk_conf *disk_conf; /* RCU, for updates: mdev->tconn->conf_update */
	sector_t known_size; /* last known size of that backing device */
};

struct drbd_md_io {
	unsigned int done;
	int error;
};

struct bm_io_work {
	struct drbd_work w;
	char *why;
	enum bm_flag flags;
	int (*io_fn)(struct drbd_conf *mdev);
	void (*done)(struct drbd_conf *mdev, int rv);
};

enum write_ordering_e {
	WO_none,
	WO_drain_io,
	WO_bdev_flush,
};

struct fifo_buffer {
	unsigned int head_index;
	unsigned int size;
	int total; /* sum of all values */
	int values[0];
};
extern struct fifo_buffer *fifo_alloc(int fifo_size);

/* flag bits per tconn */
enum {
	NET_CONGESTED,		/* The data socket is congested */
	RESOLVE_CONFLICTS,	/* Set on one node, cleared on the peer! */
	SEND_PING,		/* whether asender should send a ping asap */
	SIGNAL_ASENDER,		/* whether asender wants to be interrupted */
	GOT_PING_ACK,		/* set when we receive a ping_ack packet, ping_wait gets woken */
	CONN_WD_ST_CHG_REQ,	/* A cluster wide state change on the connection is active */
	CONN_WD_ST_CHG_OKAY,
	CONN_WD_ST_CHG_FAIL,
	CONN_DRY_RUN,		/* Expect disconnect after resync handshake. */
	CREATE_BARRIER,		/* next P_DATA is preceded by a P_BARRIER */
	STATE_SENT,		/* Do not change state/UUIDs while this is set */
	CALLBACK_PENDING,	/* Whether we have a call_usermodehelper(, UMH_WAIT_PROC)
				 * pending, from drbd worker context.
				 * If set, bdi_write_congested() returns true,
				 * so shrink_page_list() would not recurse into,
				 * and potentially deadlock on, this drbd worker.
				 */
	DISCONNECT_SENT,
};

struct drbd_tconn {			/* is a resource from the config file */
	char *name;			/* Resource name */
	struct list_head all_tconn;	/* linked on global drbd_tconns */
	struct kref kref;
	struct idr volumes;		/* <tconn, vnr> to mdev mapping */
	enum drbd_conns cstate;		/* Only C_STANDALONE to C_WF_REPORT_PARAMS */
	unsigned susp:1;		/* IO suspended by user */
	unsigned susp_nod:1;		/* IO suspended because no data */
	unsigned susp_fen:1;		/* IO suspended because fence peer handler runs */
	struct mutex cstate_mutex;	/* Protects graceful disconnects */

	unsigned long flags;
	struct net_conf *net_conf;	/* content protected by rcu */
	struct mutex conf_update;	/* mutex for ready-copy-update of net_conf and disk_conf */
	wait_queue_head_t ping_wait;	/* Woken upon reception of a ping, and a state change */
	struct res_opts res_opts;

	struct sockaddr_storage my_addr;
	int my_addr_len;
	struct sockaddr_storage peer_addr;
	int peer_addr_len;

	struct drbd_socket data;	/* data/barrier/cstate/parameter packets */
	struct drbd_socket meta;	/* ping/ack (metadata) packets */
	int agreed_pro_version;		/* actually used protocol version */
	unsigned long last_received;	/* in jiffies, either socket */
	unsigned int ko_count;

	spinlock_t req_lock;

	struct list_head transfer_log;	/* all requests not yet fully processed */

	struct crypto_hash *cram_hmac_tfm;
	struct crypto_hash *integrity_tfm;  /* checksums we compute, updates protected by tconn->data->mutex */
	struct crypto_hash *peer_integrity_tfm;  /* checksums we verify, only accessed from receiver thread  */
	struct crypto_hash *csums_tfm;
	struct crypto_hash *verify_tfm;
	void *int_dig_in;
	void *int_dig_vv;

	/* receiver side */
	struct drbd_epoch *current_epoch;
	spinlock_t epoch_lock;
	unsigned int epochs;
	enum write_ordering_e write_ordering;
	atomic_t current_tle_nr;	/* transfer log epoch number */
	unsigned current_tle_writes;	/* writes seen within this tl epoch */

	unsigned long last_reconnect_jif;
	struct drbd_thread receiver;
	struct drbd_thread worker;
	struct drbd_thread asender;
	cpumask_var_t cpu_mask;

	/* sender side */
	struct drbd_work_queue sender_work;

	struct {
		/* whether this sender thread
		 * has processed a single write yet. */
		bool seen_any_write_yet;

		/* Which barrier number to send with the next P_BARRIER */
		int current_epoch_nr;

		/* how many write requests have been sent
		 * with req->epoch == current_epoch_nr.
		 * If none, no P_BARRIER will be sent. */
		unsigned current_epoch_writes;
	} send;
};

struct submit_worker {
	struct workqueue_struct *wq;
	struct work_struct worker;

	spinlock_t lock;
	struct list_head writes;
};

struct drbd_conf {
	struct drbd_tconn *tconn;
	int vnr;			/* volume number within the connection */
	struct kref kref;

	/* things that are stored as / read from meta data on disk */
	unsigned long flags;

	/* configured by drbdsetup */
	struct drbd_backing_dev *ldev __protected_by(local);

	sector_t p_size;     /* partner's disk size */
	struct request_queue *rq_queue;
	struct block_device *this_bdev;
	struct gendisk	    *vdisk;

	unsigned long last_reattach_jif;
	struct drbd_work  resync_work,
			  unplug_work,
			  go_diskless,
			  md_sync_work,
			  start_resync_work;
	struct timer_list resync_timer;
	struct timer_list md_sync_timer;
	struct timer_list start_resync_timer;
	struct timer_list request_timer;
#ifdef DRBD_DEBUG_MD_SYNC
	struct {
		unsigned int line;
		const char* func;
	} last_md_mark_dirty;
#endif

	/* Used after attach while negotiating new disk state. */
	union drbd_state new_state_tmp;

	union drbd_dev_state state;
	wait_queue_head_t misc_wait;
	wait_queue_head_t state_wait;  /* upon each state change. */
	unsigned int send_cnt;
	unsigned int recv_cnt;
	unsigned int read_cnt;
	unsigned int writ_cnt;
	unsigned int al_writ_cnt;
	unsigned int bm_writ_cnt;
	atomic_t ap_bio_cnt;	 /* Requests we need to complete */
	atomic_t ap_pending_cnt; /* AP data packets on the wire, ack expected */
	atomic_t rs_pending_cnt; /* RS request/data packets on the wire */
	atomic_t unacked_cnt;	 /* Need to send replies for */
	atomic_t local_cnt;	 /* Waiting for local completion */

	/* Interval tree of pending local requests */
	struct rb_root read_requests;
	struct rb_root write_requests;

	/* blocks to resync in this run [unit BM_BLOCK_SIZE] */
	unsigned long rs_total;
	/* number of resync blocks that failed in this run */
	unsigned long rs_failed;
	/* Syncer's start time [unit jiffies] */
	unsigned long rs_start;
	/* cumulated time in PausedSyncX state [unit jiffies] */
	unsigned long rs_paused;
	/* skipped because csum was equal [unit BM_BLOCK_SIZE] */
	unsigned long rs_same_csum;
#define DRBD_SYNC_MARKS 8
#define DRBD_SYNC_MARK_STEP (3*HZ)
	/* block not up-to-date at mark [unit BM_BLOCK_SIZE] */
	unsigned long rs_mark_left[DRBD_SYNC_MARKS];
	/* marks's time [unit jiffies] */
	unsigned long rs_mark_time[DRBD_SYNC_MARKS];
	/* current index into rs_mark_{left,time} */
	int rs_last_mark;
	unsigned long rs_last_bcast; /* [unit jiffies] */

	/* where does the admin want us to start? (sector) */
	sector_t ov_start_sector;
	sector_t ov_stop_sector;
	/* where are we now? (sector) */
	sector_t ov_position;
	/* Start sector of out of sync range (to merge printk reporting). */
	sector_t ov_last_oos_start;
	/* size of out-of-sync range in sectors. */
	sector_t ov_last_oos_size;
	unsigned long ov_left; /* in bits */

	struct drbd_bitmap *bitmap;
	unsigned long bm_resync_fo; /* bit offset for drbd_bm_find_next */

	/* Used to track operations of resync... */
	struct lru_cache *resync;
	/* Number of locked elements in resync LRU */
	unsigned int resync_locked;
	/* resync extent number waiting for application requests */
	unsigned int resync_wenr;

	int open_cnt;
	u64 *p_uuid;

	struct list_head active_ee; /* IO in progress (P_DATA gets written to disk) */
	struct list_head sync_ee;   /* IO in progress (P_RS_DATA_REPLY gets written to disk) */
	struct list_head done_ee;   /* need to send P_WRITE_ACK */
	struct list_head read_ee;   /* [RS]P_DATA_REQUEST being read */
	struct list_head net_ee;    /* zero-copy network send in progress */

	int next_barrier_nr;
	struct list_head resync_reads;
	atomic_t pp_in_use;		/* allocated from page pool */
	atomic_t pp_in_use_by_net;	/* sendpage()d, still referenced by tcp */
	wait_queue_head_t ee_wait;
	struct page *md_io_page;	/* one page buffer for md_io */
	struct drbd_md_io md_io;
	atomic_t md_io_in_use;		/* protects the md_io, md_io_page and md_io_tmpp */
	spinlock_t al_lock;
	wait_queue_head_t al_wait;
	struct lru_cache *act_log;	/* activity log */
	unsigned int al_tr_number;
	int al_tr_cycle;
	wait_queue_head_t seq_wait;
	atomic_t packet_seq;
	unsigned int peer_seq;
	spinlock_t peer_seq_lock;
	unsigned int minor;
	unsigned long comm_bm_set; /* communicated number of set bits. */
	struct bm_io_work bm_io_work;
	u64 ed_uuid; /* UUID of the exposed data */
	struct mutex own_state_mutex;
	struct mutex *state_mutex; /* either own_state_mutex or mdev->tconn->cstate_mutex */
	char congestion_reason;  /* Why we where congested... */
	atomic_t rs_sect_in; /* for incoming resync data rate, SyncTarget */
	atomic_t rs_sect_ev; /* for submitted resync data rate, both */
	int rs_last_sect_ev; /* counter to compare with */
	int rs_last_events;  /* counter of read or write "events" (unit sectors)
			      * on the lower level device when we last looked. */
	int c_sync_rate; /* current resync rate after syncer throttle magic */
	struct fifo_buffer *rs_plan_s; /* correction values of resync planer (RCU, tconn->conn_update) */
	int rs_in_flight; /* resync sectors in flight (to proxy, in proxy and from proxy) */
	atomic_t ap_in_flight; /* App sectors in flight (waiting for ack) */
	unsigned int peer_max_bio_size;
	unsigned int local_max_bio_size;

	/* any requests that would block in drbd_make_request()
	 * are deferred to this single-threaded work queue */
	struct submit_worker submit;
};

static inline struct drbd_conf *minor_to_mdev(unsigned int minor)
{
	return (struct drbd_conf *)idr_find(&minors, minor);
}

static inline unsigned int mdev_to_minor(struct drbd_conf *mdev)
{
	return mdev->minor;
}

static inline struct drbd_conf *vnr_to_mdev(struct drbd_tconn *tconn, int vnr)
{
	return (struct drbd_conf *)idr_find(&tconn->volumes, vnr);
}

/*
 * function declarations
 *************************/

/* drbd_main.c */

enum dds_flags {
	DDSF_FORCED    = 1,
	DDSF_NO_RESYNC = 2, /* Do not run a resync for the new space */
};

extern void drbd_init_set_defaults(struct drbd_conf *mdev);
extern int  drbd_thread_start(struct drbd_thread *thi);
extern void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait);
extern char *drbd_task_to_thread_name(struct drbd_tconn *tconn, struct task_struct *task);
#ifdef CONFIG_SMP
extern void drbd_thread_current_set_cpu(struct drbd_thread *thi);
extern void drbd_calc_cpu_mask(struct drbd_tconn *tconn);
#else
#define drbd_thread_current_set_cpu(A) ({})
#define drbd_calc_cpu_mask(A) ({})
#endif
extern void tl_release(struct drbd_tconn *, unsigned int barrier_nr,
		       unsigned int set_size);
extern void tl_clear(struct drbd_tconn *);
extern void drbd_free_sock(struct drbd_tconn *tconn);
extern int drbd_send(struct drbd_tconn *tconn, struct socket *sock,
		     void *buf, size_t size, unsigned msg_flags);
extern int drbd_send_all(struct drbd_tconn *, struct socket *, void *, size_t,
			 unsigned);

extern int __drbd_send_protocol(struct drbd_tconn *tconn, enum drbd_packet cmd);
extern int drbd_send_protocol(struct drbd_tconn *tconn);
extern int drbd_send_uuids(struct drbd_conf *mdev);
extern int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev);
extern void drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev);
extern int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags);
extern int drbd_send_state(struct drbd_conf *mdev, union drbd_state s);
extern int drbd_send_current_state(struct drbd_conf *mdev);
extern int drbd_send_sync_param(struct drbd_conf *mdev);
extern void drbd_send_b_ack(struct drbd_tconn *tconn, u32 barrier_nr,
			    u32 set_size);
extern int drbd_send_ack(struct drbd_conf *, enum drbd_packet,
			 struct drbd_peer_request *);
extern void drbd_send_ack_rp(struct drbd_conf *mdev, enum drbd_packet cmd,
			     struct p_block_req *rp);
extern void drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packet cmd,
			     struct p_data *dp, int data_size);
extern int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packet cmd,
			    sector_t sector, int blksize, u64 block_id);
extern int drbd_send_out_of_sync(struct drbd_conf *, struct drbd_request *);
extern int drbd_send_block(struct drbd_conf *, enum drbd_packet,
			   struct drbd_peer_request *);
extern int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req);
extern int drbd_send_drequest(struct drbd_conf *mdev, int cmd,
			      sector_t sector, int size, u64 block_id);
extern int drbd_send_drequest_csum(struct drbd_conf *mdev, sector_t sector,
				   int size, void *digest, int digest_size,
				   enum drbd_packet cmd);
extern int drbd_send_ov_request(struct drbd_conf *mdev,sector_t sector,int size);

extern int drbd_send_bitmap(struct drbd_conf *mdev);
extern void drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode);
extern void conn_send_sr_reply(struct drbd_tconn *tconn, enum drbd_state_rv retcode);
extern void drbd_free_bc(struct drbd_backing_dev *ldev);
extern void drbd_mdev_cleanup(struct drbd_conf *mdev);
void drbd_print_uuids(struct drbd_conf *mdev, const char *text);

extern void conn_md_sync(struct drbd_tconn *tconn);
extern void drbd_md_sync(struct drbd_conf *mdev);
extern int  drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev);
extern void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
extern void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
extern void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local);
extern void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local);
extern void drbd_uuid_move_history(struct drbd_conf *mdev) __must_hold(local);
extern void __drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
extern void drbd_md_set_flag(struct drbd_conf *mdev, int flags) __must_hold(local);
extern void drbd_md_clear_flag(struct drbd_conf *mdev, int flags)__must_hold(local);
extern int drbd_md_test_flag(struct drbd_backing_dev *, int);
#ifndef DRBD_DEBUG_MD_SYNC
extern void drbd_md_mark_dirty(struct drbd_conf *mdev);
#else
#define drbd_md_mark_dirty(m)	drbd_md_mark_dirty_(m, __LINE__ , __func__ )
extern void drbd_md_mark_dirty_(struct drbd_conf *mdev,
		unsigned int line, const char *func);
#endif
extern void drbd_queue_bitmap_io(struct drbd_conf *mdev,
				 int (*io_fn)(struct drbd_conf *),
				 void (*done)(struct drbd_conf *, int),
				 char *why, enum bm_flag flags);
extern int drbd_bitmap_io(struct drbd_conf *mdev,
		int (*io_fn)(struct drbd_conf *),
		char *why, enum bm_flag flags);
extern int drbd_bitmap_io_from_worker(struct drbd_conf *mdev,
		int (*io_fn)(struct drbd_conf *),
		char *why, enum bm_flag flags);
extern int drbd_bmio_set_n_write(struct drbd_conf *mdev);
extern int drbd_bmio_clear_n_write(struct drbd_conf *mdev);
extern void drbd_ldev_destroy(struct drbd_conf *mdev);

/* Meta data layout
 *
 * We currently have two possible layouts.
 * Offsets in (512 byte) sectors.
 * external:
 *   |----------- md_size_sect ------------------|
 *   [ 4k superblock ][ activity log ][  Bitmap  ]
 *   | al_offset == 8 |
 *   | bm_offset = al_offset + X      |
 *  ==> bitmap sectors = md_size_sect - bm_offset
 *
 *  Variants:
 *     old, indexed fixed size meta data:
 *
 * internal:
 *            |----------- md_size_sect ------------------|
 * [data.....][  Bitmap  ][ activity log ][ 4k superblock ][padding*]
 *                        | al_offset < 0 |
 *            | bm_offset = al_offset - Y |
 *  ==> bitmap sectors = Y = al_offset - bm_offset
 *
 *  [padding*] are zero or up to 7 unused 512 Byte sectors to the
 *  end of the device, so that the [4k superblock] will be 4k aligned.
 *
 *  The activity log consists of 4k transaction blocks,
 *  which are written in a ring-buffer, or striped ring-buffer like fashion,
 *  which are writtensize used to be fixed 32kB,
 *  but is about to become configurable.
 */

/* Our old fixed size meta data layout
 * allows up to about 3.8TB, so if you want more,
 * you need to use the "flexible" meta data format. */
#define MD_128MB_SECT (128LLU << 11)  /* 128 MB, unit sectors */
#define MD_4kB_SECT	 8
#define MD_32kB_SECT	64

/* One activity log extent represents 4M of storage */
#define AL_EXTENT_SHIFT 22
#define AL_EXTENT_SIZE (1<<AL_EXTENT_SHIFT)

/* We could make these currently hardcoded constants configurable
 * variables at create-md time (or even re-configurable at runtime?).
 * Which will require some more changes to the DRBD "super block"
 * and attach code.
 *
 * updates per transaction:
 *   This many changes to the active set can be logged with one transaction.
 *   This number is arbitrary.
 * context per transaction:
 *   This many context extent numbers are logged with each transaction.
 *   This number is resulting from the transaction block size (4k), the layout
 *   of the transaction header, and the number of updates per transaction.
 *   See drbd_actlog.c:struct al_transaction_on_disk
 * */
#define AL_UPDATES_PER_TRANSACTION	 64	// arbitrary
#define AL_CONTEXT_PER_TRANSACTION	919	// (4096 - 36 - 6*64)/4

#if BITS_PER_LONG == 32
#define LN2_BPL 5
#define cpu_to_lel(A) cpu_to_le32(A)
#define lel_to_cpu(A) le32_to_cpu(A)
#elif BITS_PER_LONG == 64
#define LN2_BPL 6
#define cpu_to_lel(A) cpu_to_le64(A)
#define lel_to_cpu(A) le64_to_cpu(A)
#else
#error "LN2 of BITS_PER_LONG unknown!"
#endif

/* resync bitmap */
/* 16MB sized 'bitmap extent' to track syncer usage */
struct bm_extent {
	int rs_left; /* number of bits set (out of sync) in this extent. */
	int rs_failed; /* number of failed resync requests in this extent. */
	unsigned long flags;
	struct lc_element lce;
};

#define BME_NO_WRITES  0  /* bm_extent.flags: no more requests on this one! */
#define BME_LOCKED     1  /* bm_extent.flags: syncer active on this one. */
#define BME_PRIORITY   2  /* finish resync IO on this extent ASAP! App IO waiting! */

/* drbd_bitmap.c */
/*
 * We need to store one bit for a block.
 * Example: 1GB disk @ 4096 byte blocks ==> we need 32 KB bitmap.
 * Bit 0 ==> local node thinks this block is binary identical on both nodes
 * Bit 1 ==> local node thinks this block needs to be synced.
 */

#define SLEEP_TIME (HZ/10)

/* We do bitmap IO in units of 4k blocks.
 * We also still have a hardcoded 4k per bit relation. */
#define BM_BLOCK_SHIFT	12			 /* 4k per bit */
#define BM_BLOCK_SIZE	 (1<<BM_BLOCK_SHIFT)
/* mostly arbitrarily set the represented size of one bitmap extent,
 * aka resync extent, to 16 MiB (which is also 512 Byte worth of bitmap
 * at 4k per bit resolution) */
#define BM_EXT_SHIFT	 24	/* 16 MiB per resync extent */
#define BM_EXT_SIZE	 (1<<BM_EXT_SHIFT)

#if (BM_EXT_SHIFT != 24) || (BM_BLOCK_SHIFT != 12)
#error "HAVE YOU FIXED drbdmeta AS WELL??"
#endif

/* thus many _storage_ sectors are described by one bit */
#define BM_SECT_TO_BIT(x)   ((x)>>(BM_BLOCK_SHIFT-9))
#define BM_BIT_TO_SECT(x)   ((sector_t)(x)<<(BM_BLOCK_SHIFT-9))
#define BM_SECT_PER_BIT     BM_BIT_TO_SECT(1)

/* bit to represented kilo byte conversion */
#define Bit2KB(bits) ((bits)<<(BM_BLOCK_SHIFT-10))

/* in which _bitmap_ extent (resp. sector) the bit for a certain
 * _storage_ sector is located in */
#define BM_SECT_TO_EXT(x)   ((x)>>(BM_EXT_SHIFT-9))

/* how much _storage_ sectors we have per bitmap sector */
#define BM_EXT_TO_SECT(x)   ((sector_t)(x) << (BM_EXT_SHIFT-9))
#define BM_SECT_PER_EXT     BM_EXT_TO_SECT(1)

/* in one sector of the bitmap, we have this many activity_log extents. */
#define AL_EXT_PER_BM_SECT  (1 << (BM_EXT_SHIFT - AL_EXTENT_SHIFT))

#define BM_BLOCKS_PER_BM_EXT_B (BM_EXT_SHIFT - BM_BLOCK_SHIFT)
#define BM_BLOCKS_PER_BM_EXT_MASK  ((1<<BM_BLOCKS_PER_BM_EXT_B) - 1)

/* the extent in "PER_EXTENT" below is an activity log extent
 * we need that many (long words/bytes) to store the bitmap
 *		     of one AL_EXTENT_SIZE chunk of storage.
 * we can store the bitmap for that many AL_EXTENTS within
 * one sector of the _on_disk_ bitmap:
 * bit	 0	  bit 37   bit 38	     bit (512*8)-1
 *	     ...|........|........|.. // ..|........|
 * sect. 0	 `296	  `304			   ^(512*8*8)-1
 *
#define BM_WORDS_PER_EXT    ( (AL_EXT_SIZE/BM_BLOCK_SIZE) / BITS_PER_LONG )
#define BM_BYTES_PER_EXT    ( (AL_EXT_SIZE/BM_BLOCK_SIZE) / 8 )  // 128
#define BM_EXT_PER_SECT	    ( 512 / BM_BYTES_PER_EXTENT )	 //   4
 */

#define DRBD_MAX_SECTORS_32 (0xffffffffLU)
/* we have a certain meta data variant that has a fixed on-disk size of 128
 * MiB, of which 4k are our "superblock", and 32k are the fixed size activity
 * log, leaving this many sectors for the bitmap.
 */

#define DRBD_MAX_SECTORS_FIXED_BM \
	  ((MD_128MB_SECT - MD_32kB_SECT - MD_4kB_SECT) * (1LL<<(BM_EXT_SHIFT-9)))
#if !defined(CONFIG_LBDAF) && BITS_PER_LONG == 32
#define DRBD_MAX_SECTORS      DRBD_MAX_SECTORS_32
#define DRBD_MAX_SECTORS_FLEX DRBD_MAX_SECTORS_32
#else
#define DRBD_MAX_SECTORS      DRBD_MAX_SECTORS_FIXED_BM
/* 16 TB in units of sectors */
#if BITS_PER_LONG == 32
/* adjust by one page worth of bitmap,
 * so we won't wrap around in drbd_bm_find_next_bit.
 * you should use 64bit OS for that much storage, anyways. */
#define DRBD_MAX_SECTORS_FLEX BM_BIT_TO_SECT(0xffff7fff)
#else
/* we allow up to 1 PiB now on 64bit architecture with "flexible" meta data */
#define DRBD_MAX_SECTORS_FLEX (1UL << 51)
/* corresponds to (1UL << 38) bits right now. */
#endif
#endif

/* BIO_MAX_SIZE is 256 * PAGE_CACHE_SIZE,
 * so for typical PAGE_CACHE_SIZE of 4k, that is (1<<20) Byte.
 * Since we may live in a mixed-platform cluster,
 * we limit us to a platform agnostic constant here for now.
 * A followup commit may allow even bigger BIO sizes,
 * once we thought that through. */
#define DRBD_MAX_BIO_SIZE (1U << 20)
#if DRBD_MAX_BIO_SIZE > BIO_MAX_SIZE
#error Architecture not supported: DRBD_MAX_BIO_SIZE > BIO_MAX_SIZE
#endif
#define DRBD_MAX_BIO_SIZE_SAFE (1U << 12)       /* Works always = 4k */

#define DRBD_MAX_SIZE_H80_PACKET (1U << 15) /* Header 80 only allows packets up to 32KiB data */
#define DRBD_MAX_BIO_SIZE_P95    (1U << 17) /* Protocol 95 to 99 allows bios up to 128KiB */

extern int  drbd_bm_init(struct drbd_conf *mdev);
extern int  drbd_bm_resize(struct drbd_conf *mdev, sector_t sectors, int set_new_bits);
extern void drbd_bm_cleanup(struct drbd_conf *mdev);
extern void drbd_bm_set_all(struct drbd_conf *mdev);
extern void drbd_bm_clear_all(struct drbd_conf *mdev);
/* set/clear/test only a few bits at a time */
extern int  drbd_bm_set_bits(
		struct drbd_conf *mdev, unsigned long s, unsigned long e);
extern int  drbd_bm_clear_bits(
		struct drbd_conf *mdev, unsigned long s, unsigned long e);
extern int drbd_bm_count_bits(
	struct drbd_conf *mdev, const unsigned long s, const unsigned long e);
/* bm_set_bits variant for use while holding drbd_bm_lock,
 * may process the whole bitmap in one go */
extern void _drbd_bm_set_bits(struct drbd_conf *mdev,
		const unsigned long s, const unsigned long e);
extern int  drbd_bm_test_bit(struct drbd_conf *mdev, unsigned long bitnr);
extern int  drbd_bm_e_weight(struct drbd_conf *mdev, unsigned long enr);
extern int  drbd_bm_write_page(struct drbd_conf *mdev, unsigned int idx) __must_hold(local);
extern int  drbd_bm_read(struct drbd_conf *mdev) __must_hold(local);
extern void drbd_bm_mark_for_writeout(struct drbd_conf *mdev, int page_nr);
extern int  drbd_bm_write(struct drbd_conf *mdev) __must_hold(local);
extern int  drbd_bm_write_hinted(struct drbd_conf *mdev) __must_hold(local);
extern int drbd_bm_write_all(struct drbd_conf *mdev) __must_hold(local);
extern int  drbd_bm_write_copy_pages(struct drbd_conf *mdev) __must_hold(local);
extern size_t	     drbd_bm_words(struct drbd_conf *mdev);
extern unsigned long drbd_bm_bits(struct drbd_conf *mdev);
extern sector_t      drbd_bm_capacity(struct drbd_conf *mdev);

#define DRBD_END_OF_BITMAP	(~(unsigned long)0)
extern unsigned long drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo);
/* bm_find_next variants for use while you hold drbd_bm_lock() */
extern unsigned long _drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo);
extern unsigned long _drbd_bm_find_next_zero(struct drbd_conf *mdev, unsigned long bm_fo);
extern unsigned long _drbd_bm_total_weight(struct drbd_conf *mdev);
extern unsigned long drbd_bm_total_weight(struct drbd_conf *mdev);
extern int drbd_bm_rs_done(struct drbd_conf *mdev);
/* for receive_bitmap */
extern void drbd_bm_merge_lel(struct drbd_conf *mdev, size_t offset,
		size_t number, unsigned long *buffer);
/* for _drbd_send_bitmap */
extern void drbd_bm_get_lel(struct drbd_conf *mdev, size_t offset,
		size_t number, unsigned long *buffer);

extern void drbd_bm_lock(struct drbd_conf *mdev, char *why, enum bm_flag flags);
extern void drbd_bm_unlock(struct drbd_conf *mdev);
/* drbd_main.c */

extern struct kmem_cache *drbd_request_cache;
extern struct kmem_cache *drbd_ee_cache;	/* peer requests */
extern struct kmem_cache *drbd_bm_ext_cache;	/* bitmap extents */
extern struct kmem_cache *drbd_al_ext_cache;	/* activity log extents */
extern mempool_t *drbd_request_mempool;
extern mempool_t *drbd_ee_mempool;

/* drbd's page pool, used to buffer data received from the peer,
 * or data requested by the peer.
 *
 * This does not have an emergency reserve.
 *
 * When allocating from this pool, it first takes pages from the pool.
 * Only if the pool is depleted will try to allocate from the system.
 *
 * The assumption is that pages taken from this pool will be processed,
 * and given back, "quickly", and then can be recycled, so we can avoid
 * frequent calls to alloc_page(), and still will be able to make progress even
 * under memory pressure.
 */
extern struct page *drbd_pp_pool;
extern spinlock_t   drbd_pp_lock;
extern int	    drbd_pp_vacant;
extern wait_queue_head_t drbd_pp_wait;

/* We also need a standard (emergency-reserve backed) page pool
 * for meta data IO (activity log, bitmap).
 * We can keep it global, as long as it is used as "N pages at a time".
 * 128 should be plenty, currently we probably can get away with as few as 1.
 */
#define DRBD_MIN_POOL_PAGES	128
extern mempool_t *drbd_md_io_page_pool;

/* We also need to make sure we get a bio
 * when we need it for housekeeping purposes */
extern struct bio_set *drbd_md_io_bio_set;
/* to allocate from that set */
extern struct bio *bio_alloc_drbd(gfp_t gfp_mask);

extern rwlock_t global_state_lock;

extern int conn_lowest_minor(struct drbd_tconn *tconn);
enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor, int vnr);
extern void drbd_minor_destroy(struct kref *kref);

extern int set_resource_options(struct drbd_tconn *tconn, struct res_opts *res_opts);
extern struct drbd_tconn *conn_create(const char *name, struct res_opts *res_opts);
extern void conn_destroy(struct kref *kref);
struct drbd_tconn *conn_get_by_name(const char *name);
extern struct drbd_tconn *conn_get_by_addrs(void *my_addr, int my_addr_len,
					    void *peer_addr, int peer_addr_len);
extern void conn_free_crypto(struct drbd_tconn *tconn);

extern int proc_details;

/* drbd_req */
extern void do_submit(struct work_struct *ws);
extern void __drbd_make_request(struct drbd_conf *, struct bio *, unsigned long);
extern void drbd_make_request(struct request_queue *q, struct bio *bio);
extern int drbd_read_remote(struct drbd_conf *mdev, struct drbd_request *req);
extern int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec);
extern int is_valid_ar_handle(struct drbd_request *, sector_t);


/* drbd_nl.c */
extern int drbd_msg_put_info(const char *info);
extern void drbd_suspend_io(struct drbd_conf *mdev);
extern void drbd_resume_io(struct drbd_conf *mdev);
extern char *ppsize(char *buf, unsigned long long size);
extern sector_t drbd_new_dev_size(struct drbd_conf *, struct drbd_backing_dev *, sector_t, int);
enum determine_dev_size { dev_size_error = -1, unchanged = 0, shrunk = 1, grew = 2 };
extern enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *, enum dds_flags) __must_hold(local);
extern void resync_after_online_grow(struct drbd_conf *);
extern void drbd_reconsider_max_bio_size(struct drbd_conf *mdev);
extern enum drbd_state_rv drbd_set_role(struct drbd_conf *mdev,
					enum drbd_role new_role,
					int force);
extern bool conn_try_outdate_peer(struct drbd_tconn *tconn);
extern void conn_try_outdate_peer_async(struct drbd_tconn *tconn);
extern int drbd_khelper(struct drbd_conf *mdev, char *cmd);

/* drbd_worker.c */
extern int drbd_worker(struct drbd_thread *thi);
enum drbd_ret_code drbd_resync_after_valid(struct drbd_conf *mdev, int o_minor);
void drbd_resync_after_changed(struct drbd_conf *mdev);
extern void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side);
extern void resume_next_sg(struct drbd_conf *mdev);
extern void suspend_other_sg(struct drbd_conf *mdev);
extern int drbd_resync_finished(struct drbd_conf *mdev);
/* maybe rather drbd_main.c ? */
extern void *drbd_md_get_buffer(struct drbd_conf *mdev);
extern void drbd_md_put_buffer(struct drbd_conf *mdev);
extern int drbd_md_sync_page_io(struct drbd_conf *mdev,
		struct drbd_backing_dev *bdev, sector_t sector, int rw);
extern void drbd_ov_out_of_sync_found(struct drbd_conf *, sector_t, int);
extern void wait_until_done_or_force_detached(struct drbd_conf *mdev,
		struct drbd_backing_dev *bdev, unsigned int *done);
extern void drbd_rs_controller_reset(struct drbd_conf *mdev);

static inline void ov_out_of_sync_print(struct drbd_conf *mdev)
{
	if (mdev->ov_last_oos_size) {
		dev_err(DEV, "Out of sync: start=%llu, size=%lu (sectors)\n",
		     (unsigned long long)mdev->ov_last_oos_start,
		     (unsigned long)mdev->ov_last_oos_size);
	}
	mdev->ov_last_oos_size=0;
}


extern void drbd_csum_bio(struct drbd_conf *, struct crypto_hash *, struct bio *, void *);
extern void drbd_csum_ee(struct drbd_conf *, struct crypto_hash *,
			 struct drbd_peer_request *, void *);
/* worker callbacks */
extern int w_e_end_data_req(struct drbd_work *, int);
extern int w_e_end_rsdata_req(struct drbd_work *, int);
extern int w_e_end_csum_rs_req(struct drbd_work *, int);
extern int w_e_end_ov_reply(struct drbd_work *, int);
extern int w_e_end_ov_req(struct drbd_work *, int);
extern int w_ov_finished(struct drbd_work *, int);
extern int w_resync_timer(struct drbd_work *, int);
extern int w_send_write_hint(struct drbd_work *, int);
extern int w_make_resync_request(struct drbd_work *, int);
extern int w_send_dblock(struct drbd_work *, int);
extern int w_send_read_req(struct drbd_work *, int);
extern int w_prev_work_done(struct drbd_work *, int);
extern int w_e_reissue(struct drbd_work *, int);
extern int w_restart_disk_io(struct drbd_work *, int);
extern int w_send_out_of_sync(struct drbd_work *, int);
extern int w_start_resync(struct drbd_work *, int);

extern void resync_timer_fn(unsigned long data);
extern void start_resync_timer_fn(unsigned long data);

/* drbd_receiver.c */
extern int drbd_rs_should_slow_down(struct drbd_conf *mdev, sector_t sector);
extern int drbd_submit_peer_request(struct drbd_conf *,
				    struct drbd_peer_request *, const unsigned,
				    const int);
extern int drbd_free_peer_reqs(struct drbd_conf *, struct list_head *);
extern struct drbd_peer_request *drbd_alloc_peer_req(struct drbd_conf *, u64,
						     sector_t, unsigned int,
						     gfp_t) __must_hold(local);
extern void __drbd_free_peer_req(struct drbd_conf *, struct drbd_peer_request *,
				 int);
#define drbd_free_peer_req(m,e) __drbd_free_peer_req(m, e, 0)
#define drbd_free_net_peer_req(m,e) __drbd_free_peer_req(m, e, 1)
extern struct page *drbd_alloc_pages(struct drbd_conf *, unsigned int, bool);
extern void drbd_set_recv_tcq(struct drbd_conf *mdev, int tcq_enabled);
extern void _drbd_clear_done_ee(struct drbd_conf *mdev, struct list_head *to_be_freed);
extern void conn_flush_workqueue(struct drbd_tconn *tconn);
extern int drbd_connected(struct drbd_conf *mdev);
static inline void drbd_flush_workqueue(struct drbd_conf *mdev)
{
	conn_flush_workqueue(mdev->tconn);
}

/* Yes, there is kernel_setsockopt, but only since 2.6.18.
 * So we have our own copy of it here. */
static inline int drbd_setsockopt(struct socket *sock, int level, int optname,
				  char *optval, int optlen)
{
	mm_segment_t oldfs = get_fs();
	char __user *uoptval;
	int err;

	uoptval = (char __user __force *)optval;

	set_fs(KERNEL_DS);
	if (level == SOL_SOCKET)
		err = sock_setsockopt(sock, level, optname, uoptval, optlen);
	else
		err = sock->ops->setsockopt(sock, level, optname, uoptval,
					    optlen);
	set_fs(oldfs);
	return err;
}

static inline void drbd_tcp_cork(struct socket *sock)
{
	int val = 1;
	(void) drbd_setsockopt(sock, SOL_TCP, TCP_CORK,
			(char*)&val, sizeof(val));
}

static inline void drbd_tcp_uncork(struct socket *sock)
{
	int val = 0;
	(void) drbd_setsockopt(sock, SOL_TCP, TCP_CORK,
			(char*)&val, sizeof(val));
}

static inline void drbd_tcp_nodelay(struct socket *sock)
{
	int val = 1;
	(void) drbd_setsockopt(sock, SOL_TCP, TCP_NODELAY,
			(char*)&val, sizeof(val));
}

static inline void drbd_tcp_quickack(struct socket *sock)
{
	int val = 2;
	(void) drbd_setsockopt(sock, SOL_TCP, TCP_QUICKACK,
			(char*)&val, sizeof(val));
}

void drbd_bump_write_ordering(struct drbd_tconn *tconn, enum write_ordering_e wo);

/* drbd_proc.c */
extern struct proc_dir_entry *drbd_proc;
extern const struct file_operations drbd_proc_fops;
extern const char *drbd_conn_str(enum drbd_conns s);
extern const char *drbd_role_str(enum drbd_role s);

/* drbd_actlog.c */
extern int drbd_al_begin_io_nonblock(struct drbd_conf *mdev, struct drbd_interval *i);
extern void drbd_al_begin_io_commit(struct drbd_conf *mdev, bool delegate);
extern bool drbd_al_begin_io_fastpath(struct drbd_conf *mdev, struct drbd_interval *i);
extern void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool delegate);
extern void drbd_al_complete_io(struct drbd_conf *mdev, struct drbd_interval *i);
extern void drbd_rs_complete_io(struct drbd_conf *mdev, sector_t sector);
extern int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector);
extern int drbd_try_rs_begin_io(struct drbd_conf *mdev, sector_t sector);
extern void drbd_rs_cancel_all(struct drbd_conf *mdev);
extern int drbd_rs_del_all(struct drbd_conf *mdev);
extern void drbd_rs_failed_io(struct drbd_conf *mdev,
		sector_t sector, int size);
extern void drbd_advance_rs_marks(struct drbd_conf *mdev, unsigned long still_to_go);
extern void __drbd_set_in_sync(struct drbd_conf *mdev, sector_t sector,
		int size, const char *file, const unsigned int line);
#define drbd_set_in_sync(mdev, sector, size) \
	__drbd_set_in_sync(mdev, sector, size, __FILE__, __LINE__)
extern int __drbd_set_out_of_sync(struct drbd_conf *mdev, sector_t sector,
		int size, const char *file, const unsigned int line);
#define drbd_set_out_of_sync(mdev, sector, size) \
	__drbd_set_out_of_sync(mdev, sector, size, __FILE__, __LINE__)
extern void drbd_al_shrink(struct drbd_conf *mdev);

/* drbd_nl.c */
/* state info broadcast */
struct sib_info {
	enum drbd_state_info_bcast_reason sib_reason;
	union {
		struct {
			char *helper_name;
			unsigned helper_exit_code;
		};
		struct {
			union drbd_state os;
			union drbd_state ns;
		};
	};
};
void drbd_bcast_event(struct drbd_conf *mdev, const struct sib_info *sib);

/*
 * inline helper functions
 *************************/

/* see also page_chain_add and friends in drbd_receiver.c */
static inline struct page *page_chain_next(struct page *page)
{
	return (struct page *)page_private(page);
}
#define page_chain_for_each(page) \
	for (; page && ({ prefetch(page_chain_next(page)); 1; }); \
			page = page_chain_next(page))
#define page_chain_for_each_safe(page, n) \
	for (; page && ({ n = page_chain_next(page); 1; }); page = n)


static inline int drbd_peer_req_has_active_page(struct drbd_peer_request *peer_req)
{
	struct page *page = peer_req->pages;
	page_chain_for_each(page) {
		if (page_count(page) > 1)
			return 1;
	}
	return 0;
}

static inline enum drbd_state_rv
_drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
		enum chg_state_flags flags, struct completion *done)
{
	enum drbd_state_rv rv;

	read_lock(&global_state_lock);
	rv = __drbd_set_state(mdev, ns, flags, done);
	read_unlock(&global_state_lock);

	return rv;
}

static inline union drbd_state drbd_read_state(struct drbd_conf *mdev)
{
	union drbd_state rv;

	rv.i = mdev->state.i;
	rv.susp = mdev->tconn->susp;
	rv.susp_nod = mdev->tconn->susp_nod;
	rv.susp_fen = mdev->tconn->susp_fen;

	return rv;
}

enum drbd_force_detach_flags {
	DRBD_READ_ERROR,
	DRBD_WRITE_ERROR,
	DRBD_META_IO_ERROR,
	DRBD_FORCE_DETACH,
};

#define __drbd_chk_io_error(m,f) __drbd_chk_io_error_(m,f, __func__)
static inline void __drbd_chk_io_error_(struct drbd_conf *mdev,
		enum drbd_force_detach_flags df,
		const char *where)
{
	enum drbd_io_error_p ep;

	rcu_read_lock();
	ep = rcu_dereference(mdev->ldev->disk_conf)->on_io_error;
	rcu_read_unlock();
	switch (ep) {
	case EP_PASS_ON: /* FIXME would this be better named "Ignore"? */
		if (df == DRBD_READ_ERROR || df == DRBD_WRITE_ERROR) {
			if (__ratelimit(&drbd_ratelimit_state))
				dev_err(DEV, "Local IO failed in %s.\n", where);
			if (mdev->state.disk > D_INCONSISTENT)
				_drbd_set_state(_NS(mdev, disk, D_INCONSISTENT), CS_HARD, NULL);
			break;
		}
		/* NOTE fall through for DRBD_META_IO_ERROR or DRBD_FORCE_DETACH */
	case EP_DETACH:
	case EP_CALL_HELPER:
		/* Remember whether we saw a READ or WRITE error.
		 *
		 * Recovery of the affected area for WRITE failure is covered
		 * by the activity log.
		 * READ errors may fall outside that area though. Certain READ
		 * errors can be "healed" by writing good data to the affected
		 * blocks, which triggers block re-allocation in lower layers.
		 *
		 * If we can not write the bitmap after a READ error,
		 * we may need to trigger a full sync (see w_go_diskless()).
		 *
		 * Force-detach is not really an IO error, but rather a
		 * desperate measure to try to deal with a completely
		 * unresponsive lower level IO stack.
		 * Still it should be treated as a WRITE error.
		 *
		 * Meta IO error is always WRITE error:
		 * we read meta data only once during attach,
		 * which will fail in case of errors.
		 */
		set_bit(WAS_IO_ERROR, &mdev->flags);
		if (df == DRBD_READ_ERROR)
			set_bit(WAS_READ_ERROR, &mdev->flags);
		if (df == DRBD_FORCE_DETACH)
			set_bit(FORCE_DETACH, &mdev->flags);
		if (mdev->state.disk > D_FAILED) {
			_drbd_set_state(_NS(mdev, disk, D_FAILED), CS_HARD, NULL);
			dev_err(DEV,
				"Local IO failed in %s. Detaching...\n", where);
		}
		break;
	}
}

/**
 * drbd_chk_io_error: Handle the on_io_error setting, should be called from all io completion handlers
 * @mdev:	 DRBD device.
 * @error:	 Error code passed to the IO completion callback
 * @forcedetach: Force detach. I.e. the error happened while accessing the meta data
 *
 * See also drbd_main.c:after_state_ch() if (os.disk > D_FAILED && ns.disk == D_FAILED)
 */
#define drbd_chk_io_error(m,e,f) drbd_chk_io_error_(m,e,f, __func__)
static inline void drbd_chk_io_error_(struct drbd_conf *mdev,
	int error, enum drbd_force_detach_flags forcedetach, const char *where)
{
	if (error) {
		unsigned long flags;
		spin_lock_irqsave(&mdev->tconn->req_lock, flags);
		__drbd_chk_io_error_(mdev, forcedetach, where);
		spin_unlock_irqrestore(&mdev->tconn->req_lock, flags);
	}
}


/**
 * drbd_md_first_sector() - Returns the first sector number of the meta data area
 * @bdev:	Meta data block device.
 *
 * BTW, for internal meta data, this happens to be the maximum capacity
 * we could agree upon with our peer node.
 */
static inline sector_t drbd_md_first_sector(struct drbd_backing_dev *bdev)
{
	switch (bdev->md.meta_dev_idx) {
	case DRBD_MD_INDEX_INTERNAL:
	case DRBD_MD_INDEX_FLEX_INT:
		return bdev->md.md_offset + bdev->md.bm_offset;
	case DRBD_MD_INDEX_FLEX_EXT:
	default:
		return bdev->md.md_offset;
	}
}

/**
 * drbd_md_last_sector() - Return the last sector number of the meta data area
 * @bdev:	Meta data block device.
 */
static inline sector_t drbd_md_last_sector(struct drbd_backing_dev *bdev)
{
	switch (bdev->md.meta_dev_idx) {
	case DRBD_MD_INDEX_INTERNAL:
	case DRBD_MD_INDEX_FLEX_INT:
		return bdev->md.md_offset + MD_4kB_SECT -1;
	case DRBD_MD_INDEX_FLEX_EXT:
	default:
		return bdev->md.md_offset + bdev->md.md_size_sect -1;
	}
}

/* Returns the number of 512 byte sectors of the device */
static inline sector_t drbd_get_capacity(struct block_device *bdev)
{
	/* return bdev ? get_capacity(bdev->bd_disk) : 0; */
	return bdev ? i_size_read(bdev->bd_inode) >> 9 : 0;
}

/**
 * drbd_get_max_capacity() - Returns the capacity we announce to out peer
 * @bdev:	Meta data block device.
 *
 * returns the capacity we announce to out peer.  we clip ourselves at the
 * various MAX_SECTORS, because if we don't, current implementation will
 * oops sooner or later
 */
static inline sector_t drbd_get_max_capacity(struct drbd_backing_dev *bdev)
{
	sector_t s;

	switch (bdev->md.meta_dev_idx) {
	case DRBD_MD_INDEX_INTERNAL:
	case DRBD_MD_INDEX_FLEX_INT:
		s = drbd_get_capacity(bdev->backing_bdev)
			? min_t(sector_t, DRBD_MAX_SECTORS_FLEX,
				drbd_md_first_sector(bdev))
			: 0;
		break;
	case DRBD_MD_INDEX_FLEX_EXT:
		s = min_t(sector_t, DRBD_MAX_SECTORS_FLEX,
				drbd_get_capacity(bdev->backing_bdev));
		/* clip at maximum size the meta device can support */
		s = min_t(sector_t, s,
			BM_EXT_TO_SECT(bdev->md.md_size_sect
				     - bdev->md.bm_offset));
		break;
	default:
		s = min_t(sector_t, DRBD_MAX_SECTORS,
				drbd_get_capacity(bdev->backing_bdev));
	}
	return s;
}

/**
 * drbd_md_ss() - Return the sector number of our meta data super block
 * @bdev:	Meta data block device.
 */
static inline sector_t drbd_md_ss(struct drbd_backing_dev *bdev)
{
	const int meta_dev_idx = bdev->md.meta_dev_idx;

	if (meta_dev_idx == DRBD_MD_INDEX_FLEX_EXT)
		return 0;

	/* Since drbd08, internal meta data is always "flexible".
	 * position: last 4k aligned block of 4k size */
	if (meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
	    meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)
		return (drbd_get_capacity(bdev->backing_bdev) & ~7ULL) - 8;

	/* external, some index; this is the old fixed size layout */
	return MD_128MB_SECT * bdev->md.meta_dev_idx;
}

static inline void
drbd_queue_work_front(struct drbd_work_queue *q, struct drbd_work *w)
{
	unsigned long flags;
	spin_lock_irqsave(&q->q_lock, flags);
	list_add(&w->list, &q->q);
	spin_unlock_irqrestore(&q->q_lock, flags);
	wake_up(&q->q_wait);
}

static inline void
drbd_queue_work(struct drbd_work_queue *q, struct drbd_work *w)
{
	unsigned long flags;
	spin_lock_irqsave(&q->q_lock, flags);
	list_add_tail(&w->list, &q->q);
	spin_unlock_irqrestore(&q->q_lock, flags);
	wake_up(&q->q_wait);
}

static inline void wake_asender(struct drbd_tconn *tconn)
{
	if (test_bit(SIGNAL_ASENDER, &tconn->flags))
		force_sig(DRBD_SIG, tconn->asender.task);
}

static inline void request_ping(struct drbd_tconn *tconn)
{
	set_bit(SEND_PING, &tconn->flags);
	wake_asender(tconn);
}

extern void *conn_prepare_command(struct drbd_tconn *, struct drbd_socket *);
extern void *drbd_prepare_command(struct drbd_conf *, struct drbd_socket *);
extern int conn_send_command(struct drbd_tconn *, struct drbd_socket *,
			     enum drbd_packet, unsigned int, void *,
			     unsigned int);
extern int drbd_send_command(struct drbd_conf *, struct drbd_socket *,
			     enum drbd_packet, unsigned int, void *,
			     unsigned int);

extern int drbd_send_ping(struct drbd_tconn *tconn);
extern int drbd_send_ping_ack(struct drbd_tconn *tconn);
extern int drbd_send_state_req(struct drbd_conf *, union drbd_state, union drbd_state);
extern int conn_send_state_req(struct drbd_tconn *, union drbd_state, union drbd_state);

static inline void drbd_thread_stop(struct drbd_thread *thi)
{
	_drbd_thread_stop(thi, false, true);
}

static inline void drbd_thread_stop_nowait(struct drbd_thread *thi)
{
	_drbd_thread_stop(thi, false, false);
}

static inline void drbd_thread_restart_nowait(struct drbd_thread *thi)
{
	_drbd_thread_stop(thi, true, false);
}

/* counts how many answer packets packets we expect from our peer,
 * for either explicit application requests,
 * or implicit barrier packets as necessary.
 * increased:
 *  w_send_barrier
 *  _req_mod(req, QUEUE_FOR_NET_WRITE or QUEUE_FOR_NET_READ);
 *    it is much easier and equally valid to count what we queue for the
 *    worker, even before it actually was queued or send.
 *    (drbd_make_request_common; recovery path on read io-error)
 * decreased:
 *  got_BarrierAck (respective tl_clear, tl_clear_barrier)
 *  _req_mod(req, DATA_RECEIVED)
 *     [from receive_DataReply]
 *  _req_mod(req, WRITE_ACKED_BY_PEER or RECV_ACKED_BY_PEER or NEG_ACKED)
 *     [from got_BlockAck (P_WRITE_ACK, P_RECV_ACK)]
 *     for some reason it is NOT decreased in got_NegAck,
 *     but in the resulting cleanup code from report_params.
 *     we should try to remember the reason for that...
 *  _req_mod(req, SEND_FAILED or SEND_CANCELED)
 *  _req_mod(req, CONNECTION_LOST_WHILE_PENDING)
 *     [from tl_clear_barrier]
 */
static inline void inc_ap_pending(struct drbd_conf *mdev)
{
	atomic_inc(&mdev->ap_pending_cnt);
}

#define ERR_IF_CNT_IS_NEGATIVE(which, func, line)			\
	if (atomic_read(&mdev->which) < 0)				\
		dev_err(DEV, "in %s:%d: " #which " = %d < 0 !\n",	\
			func, line,					\
			atomic_read(&mdev->which))

#define dec_ap_pending(mdev) _dec_ap_pending(mdev, __FUNCTION__, __LINE__)
static inline void _dec_ap_pending(struct drbd_conf *mdev, const char *func, int line)
{
	if (atomic_dec_and_test(&mdev->ap_pending_cnt))
		wake_up(&mdev->misc_wait);
	ERR_IF_CNT_IS_NEGATIVE(ap_pending_cnt, func, line);
}

/* counts how many resync-related answers we still expect from the peer
 *		     increase			decrease
 * C_SYNC_TARGET sends P_RS_DATA_REQUEST (and expects P_RS_DATA_REPLY)
 * C_SYNC_SOURCE sends P_RS_DATA_REPLY   (and expects P_WRITE_ACK with ID_SYNCER)
 *					   (or P_NEG_ACK with ID_SYNCER)
 */
static inline void inc_rs_pending(struct drbd_conf *mdev)
{
	atomic_inc(&mdev->rs_pending_cnt);
}

#define dec_rs_pending(mdev) _dec_rs_pending(mdev, __FUNCTION__, __LINE__)
static inline void _dec_rs_pending(struct drbd_conf *mdev, const char *func, int line)
{
	atomic_dec(&mdev->rs_pending_cnt);
	ERR_IF_CNT_IS_NEGATIVE(rs_pending_cnt, func, line);
}

/* counts how many answers we still need to send to the peer.
 * increased on
 *  receive_Data	unless protocol A;
 *			we need to send a P_RECV_ACK (proto B)
 *			or P_WRITE_ACK (proto C)
 *  receive_RSDataReply (recv_resync_read) we need to send a P_WRITE_ACK
 *  receive_DataRequest (receive_RSDataRequest) we need to send back P_DATA
 *  receive_Barrier_*	we need to send a P_BARRIER_ACK
 */
static inline void inc_unacked(struct drbd_conf *mdev)
{
	atomic_inc(&mdev->unacked_cnt);
}

#define dec_unacked(mdev) _dec_unacked(mdev, __FUNCTION__, __LINE__)
static inline void _dec_unacked(struct drbd_conf *mdev, const char *func, int line)
{
	atomic_dec(&mdev->unacked_cnt);
	ERR_IF_CNT_IS_NEGATIVE(unacked_cnt, func, line);
}

#define sub_unacked(mdev, n) _sub_unacked(mdev, n, __FUNCTION__, __LINE__)
static inline void _sub_unacked(struct drbd_conf *mdev, int n, const char *func, int line)
{
	atomic_sub(n, &mdev->unacked_cnt);
	ERR_IF_CNT_IS_NEGATIVE(unacked_cnt, func, line);
}

/**
 * get_ldev() - Increase the ref count on mdev->ldev. Returns 0 if there is no ldev
 * @M:		DRBD device.
 *
 * You have to call put_ldev() when finished working with mdev->ldev.
 */
#define get_ldev(M) __cond_lock(local, _get_ldev_if_state(M,D_INCONSISTENT))
#define get_ldev_if_state(M,MINS) __cond_lock(local, _get_ldev_if_state(M,MINS))

static inline void put_ldev(struct drbd_conf *mdev)
{
	int i = atomic_dec_return(&mdev->local_cnt);

	/* This may be called from some endio handler,
	 * so we must not sleep here. */

	__release(local);
	D_ASSERT(i >= 0);
	if (i == 0) {
		if (mdev->state.disk == D_DISKLESS)
			/* even internal references gone, safe to destroy */
			drbd_ldev_destroy(mdev);
		if (mdev->state.disk == D_FAILED) {
			/* all application IO references gone. */
			if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
				drbd_queue_work(&mdev->tconn->sender_work, &mdev->go_diskless);
		}
		wake_up(&mdev->misc_wait);
	}
}

#ifndef __CHECKER__
static inline int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins)
{
	int io_allowed;

	/* never get a reference while D_DISKLESS */
	if (mdev->state.disk == D_DISKLESS)
		return 0;

	atomic_inc(&mdev->local_cnt);
	io_allowed = (mdev->state.disk >= mins);
	if (!io_allowed)
		put_ldev(mdev);
	return io_allowed;
}
#else
extern int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins);
#endif

/* you must have an "get_ldev" reference */
static inline void drbd_get_syncer_progress(struct drbd_conf *mdev,
		unsigned long *bits_left, unsigned int *per_mil_done)
{
	/* this is to break it at compile time when we change that, in case we
	 * want to support more than (1<<32) bits on a 32bit arch. */
	typecheck(unsigned long, mdev->rs_total);

	/* note: both rs_total and rs_left are in bits, i.e. in
	 * units of BM_BLOCK_SIZE.
	 * for the percentage, we don't care. */

	if (mdev->state.conn == C_VERIFY_S || mdev->state.conn == C_VERIFY_T)
		*bits_left = mdev->ov_left;
	else
		*bits_left = drbd_bm_total_weight(mdev) - mdev->rs_failed;
	/* >> 10 to prevent overflow,
	 * +1 to prevent division by zero */
	if (*bits_left > mdev->rs_total) {
		/* doh. maybe a logic bug somewhere.
		 * may also be just a race condition
		 * between this and a disconnect during sync.
		 * for now, just prevent in-kernel buffer overflow.
		 */
		smp_rmb();
		dev_warn(DEV, "cs:%s rs_left=%lu > rs_total=%lu (rs_failed %lu)\n",
				drbd_conn_str(mdev->state.conn),
				*bits_left, mdev->rs_total, mdev->rs_failed);
		*per_mil_done = 0;
	} else {
		/* Make sure the division happens in long context.
		 * We allow up to one petabyte storage right now,
		 * at a granularity of 4k per bit that is 2**38 bits.
		 * After shift right and multiplication by 1000,
		 * this should still fit easily into a 32bit long,
		 * so we don't need a 64bit division on 32bit arch.
		 * Note: currently we don't support such large bitmaps on 32bit
		 * arch anyways, but no harm done to be prepared for it here.
		 */
		unsigned int shift = mdev->rs_total > UINT_MAX ? 16 : 10;
		unsigned long left = *bits_left >> shift;
		unsigned long total = 1UL + (mdev->rs_total >> shift);
		unsigned long tmp = 1000UL - left * 1000UL/total;
		*per_mil_done = tmp;
	}
}


/* this throttles on-the-fly application requests
 * according to max_buffers settings;
 * maybe re-implement using semaphores? */
static inline int drbd_get_max_buffers(struct drbd_conf *mdev)
{
	struct net_conf *nc;
	int mxb;

	rcu_read_lock();
	nc = rcu_dereference(mdev->tconn->net_conf);
	mxb = nc ? nc->max_buffers : 1000000;  /* arbitrary limit on open requests */
	rcu_read_unlock();

	return mxb;
}

static inline int drbd_state_is_stable(struct drbd_conf *mdev)
{
	union drbd_dev_state s = mdev->state;

	/* DO NOT add a default clause, we want the compiler to warn us
	 * for any newly introduced state we may have forgotten to add here */

	switch ((enum drbd_conns)s.conn) {
	/* new io only accepted when there is no connection, ... */
	case C_STANDALONE:
	case C_WF_CONNECTION:
	/* ... or there is a well established connection. */
	case C_CONNECTED:
	case C_SYNC_SOURCE:
	case C_SYNC_TARGET:
	case C_VERIFY_S:
	case C_VERIFY_T:
	case C_PAUSED_SYNC_S:
	case C_PAUSED_SYNC_T:
	case C_AHEAD:
	case C_BEHIND:
		/* transitional states, IO allowed */
	case C_DISCONNECTING:
	case C_UNCONNECTED:
	case C_TIMEOUT:
	case C_BROKEN_PIPE:
	case C_NETWORK_FAILURE:
	case C_PROTOCOL_ERROR:
	case C_TEAR_DOWN:
	case C_WF_REPORT_PARAMS:
	case C_STARTING_SYNC_S:
	case C_STARTING_SYNC_T:
		break;

		/* Allow IO in BM exchange states with new protocols */
	case C_WF_BITMAP_S:
		if (mdev->tconn->agreed_pro_version < 96)
			return 0;
		break;

		/* no new io accepted in these states */
	case C_WF_BITMAP_T:
	case C_WF_SYNC_UUID:
	case C_MASK:
		/* not "stable" */
		return 0;
	}

	switch ((enum drbd_disk_state)s.disk) {
	case D_DISKLESS:
	case D_INCONSISTENT:
	case D_OUTDATED:
	case D_CONSISTENT:
	case D_UP_TO_DATE:
	case D_FAILED:
		/* disk state is stable as well. */
		break;

	/* no new io accepted during transitional states */
	case D_ATTACHING:
	case D_NEGOTIATING:
	case D_UNKNOWN:
	case D_MASK:
		/* not "stable" */
		return 0;
	}

	return 1;
}

static inline int drbd_suspended(struct drbd_conf *mdev)
{
	struct drbd_tconn *tconn = mdev->tconn;

	return tconn->susp || tconn->susp_fen || tconn->susp_nod;
}

static inline bool may_inc_ap_bio(struct drbd_conf *mdev)
{
	int mxb = drbd_get_max_buffers(mdev);

	if (drbd_suspended(mdev))
		return false;
	if (test_bit(SUSPEND_IO, &mdev->flags))
		return false;

	/* to avoid potential deadlock or bitmap corruption,
	 * in various places, we only allow new application io
	 * to start during "stable" states. */

	/* no new io accepted when attaching or detaching the disk */
	if (!drbd_state_is_stable(mdev))
		return false;

	/* since some older kernels don't have atomic_add_unless,
	 * and we are within the spinlock anyways, we have this workaround.  */
	if (atomic_read(&mdev->ap_bio_cnt) > mxb)
		return false;
	if (test_bit(BITMAP_IO, &mdev->flags))
		return false;
	return true;
}

static inline bool inc_ap_bio_cond(struct drbd_conf *mdev)
{
	bool rv = false;

	spin_lock_irq(&mdev->tconn->req_lock);
	rv = may_inc_ap_bio(mdev);
	if (rv)
		atomic_inc(&mdev->ap_bio_cnt);
	spin_unlock_irq(&mdev->tconn->req_lock);

	return rv;
}

static inline void inc_ap_bio(struct drbd_conf *mdev)
{
	/* we wait here
	 *    as long as the device is suspended
	 *    until the bitmap is no longer on the fly during connection
	 *    handshake as long as we would exceed the max_buffer limit.
	 *
	 * to avoid races with the reconnect code,
	 * we need to atomic_inc within the spinlock. */

	wait_event(mdev->misc_wait, inc_ap_bio_cond(mdev));
}

static inline void dec_ap_bio(struct drbd_conf *mdev)
{
	int mxb = drbd_get_max_buffers(mdev);
	int ap_bio = atomic_dec_return(&mdev->ap_bio_cnt);

	D_ASSERT(ap_bio >= 0);

	if (ap_bio == 0 && test_bit(BITMAP_IO, &mdev->flags)) {
		if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
			drbd_queue_work(&mdev->tconn->sender_work, &mdev->bm_io_work.w);
	}

	/* this currently does wake_up for every dec_ap_bio!
	 * maybe rather introduce some type of hysteresis?
	 * e.g. (ap_bio == mxb/2 || ap_bio == 0) ? */
	if (ap_bio < mxb)
		wake_up(&mdev->misc_wait);
}

static inline bool verify_can_do_stop_sector(struct drbd_conf *mdev)
{
	return mdev->tconn->agreed_pro_version >= 97 &&
		mdev->tconn->agreed_pro_version != 100;
}

static inline int drbd_set_ed_uuid(struct drbd_conf *mdev, u64 val)
{
	int changed = mdev->ed_uuid != val;
	mdev->ed_uuid = val;
	return changed;
}

static inline int drbd_queue_order_type(struct drbd_conf *mdev)
{
	/* sorry, we currently have no working implementation
	 * of distributed TCQ stuff */
#ifndef QUEUE_ORDERED_NONE
#define QUEUE_ORDERED_NONE 0
#endif
	return QUEUE_ORDERED_NONE;
}

static inline void drbd_md_flush(struct drbd_conf *mdev)
{
	int r;

	if (mdev->ldev == NULL) {
		dev_warn(DEV, "mdev->ldev == NULL in drbd_md_flush\n");
		return;
	}

	if (test_bit(MD_NO_FUA, &mdev->flags))
		return;

	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_NOIO, NULL);
	if (r) {
		set_bit(MD_NO_FUA, &mdev->flags);
		dev_err(DEV, "meta data flush failed with status %d, disabling md-flushes\n", r);
	}
}

#endif