summaryrefslogtreecommitdiff
path: root/drivers/block/drbd/drbd_int.h
blob: c1eb4462096edf9078fdf2b8c4f14983e5595863 (plain)
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
/*
  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/version.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 int disable_sendpage;
extern int 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))

/* drbd_meta-data.c (still in drbd_main.c) */
/* 4th incarnation of the disk layout. */
#define DRBD_MD_MAGIC (DRBD_MAGIC+4)

extern struct ratelimit_state drbd_ratelimit_state;
extern struct idr minors;
extern struct list_head drbd_tconns;
extern struct mutex drbd_cfg_mutex;

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

	/* special command ids for handshake */

	P_HAND_SHAKE_M	      = 0xfff1, /* First Packet on the MetaSock */
	P_HAND_SHAKE_S	      = 0xfff2, /* First Packet on the Socket */

	P_HAND_SHAKE	      = 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;	/* Use only 24 bits of that. Ignore the highest 8 bit. */
} __packed;

struct p_header {
	union {
		struct p_header80 h80;
		struct p_header95 h95;
	};
	u8	  payload[0];
};

/*
 * short commands, packets without payload, plain p_header:
 *   P_PING
 *   P_PING_ACK
 *   P_BECOME_SYNC_TARGET
 *   P_BECOME_SYNC_SOURCE
 *   P_UNPLUG_REMOTE
 */

/*
 * commands with out-of-struct payload:
 *   P_BITMAP    (no additional fields)
 *   P_DATA, P_DATA_REPLY (see p_data)
 *   P_COMPRESSED_BITMAP (see receive_compressed_bitmap)
 */

/* 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 */

struct p_data {
	struct p_header head;
	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_DISCARD_WRITE (proto C, two-primaries conflict detection)
 *  p_block_req:
 *   P_DATA_REQUEST, P_RS_DATA_REQUEST
 */
struct p_block_ack {
	struct p_header head;
	u64	    sector;
	u64	    block_id;
	u32	    blksize;
	u32	    seq_num;
} __packed;

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

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

struct p_handshake {
	struct p_header head;   /* Note: vnr will be ignored */
	u32 protocol_min;
	u32 feature_flags;
	u32 protocol_max;

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

	u32 _pad;
	u64 reserverd[7];
} __packed;
/* 80 bytes, FIXED for the next century */

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

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

struct p_rs_param {
	struct p_header head;
	u32 rate;

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

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

struct p_rs_param_95 {
	struct p_header head;
	u32 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_WANT_LOSE = 1,
	CF_DRY_RUN = 2,
};

struct p_protocol {
	struct p_header head;
	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 {
	struct p_header head;
	u64 uuid[UI_EXTENDED_SIZE];
} __packed;

struct p_rs_uuid {
	struct p_header head;
	u64	    uuid;
} __packed;

struct p_sizes {
	struct p_header head;
	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 {
	struct p_header head;
	u32	    state;
} __packed;

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

struct p_req_state_reply {
	struct p_header head;
	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_discard {
	struct p_header head;
	u64	    block_id;
	u32	    seq_num;
	u32	    pad;
} __packed;

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

/* one bitmap packet, including the p_header,
 * should fit within one _architecture independend_ page.
 * so we need to use the fixed size 4KiB page size
 * most architectures have used for a long time.
 */
#define BM_PACKET_PAYLOAD_BYTES (4096 - sizeof(struct p_header))
#define BM_PACKET_WORDS (BM_PACKET_PAYLOAD_BYTES/sizeof(long))
#define BM_PACKET_VLI_BYTES_MAX (4096 - sizeof(struct p_compressed_bm))
#if (PAGE_SIZE < 4096)
/* drbd_send_bitmap / receive_bitmap would break horribly */
#error "PAGE_SIZE too small"
#endif

union p_polymorph {
        struct p_header           header;
        struct p_handshake       handshake;
        struct p_data            data;
        struct p_block_ack       block_ack;
        struct p_barrier         barrier;
        struct p_barrier_ack     barrier_ack;
        struct p_rs_param_89     rs_param_89;
        struct p_rs_param_95     rs_param_95;
        struct p_protocol        protocol;
        struct p_sizes           sizes;
        struct p_uuids           uuids;
        struct p_state           state;
        struct p_req_state       req_state;
        struct p_req_state_reply req_state_reply;
        struct p_block_req       block_req;
	struct p_delay_probe93   delay_probe93;
	struct p_rs_uuid         rs_uuid;
	struct p_block_desc      block_desc;
} __packed;

/**********************************************************************/
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;
	unsigned int epoch; /* barrier_nr */

	/* barrier_nr: used to check on "completion" whether this req was in
	 * the current epoch, and we therefore have to close it,
	 * starting a new epoch...
	 */

	struct list_head tl_requests; /* ring list in the transfer log */
	struct bio *master_bio;       /* master bio pointer */
	unsigned long rq_state; /* see comments above _req_mod() */
	int seq_num;
	unsigned long start_time;
};

struct drbd_tl_epoch {
	struct drbd_work w;
	struct list_head requests; /* requests before */
	struct drbd_tl_epoch *next; /* pointer to the next barrier */
	unsigned int br_number;  /* the barriers identifier. */
	int n_writes;	/* number of requests attached before this barrier */
};

struct drbd_epoch {
	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,
};
#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)

/* flag bits per mdev */
enum {
	CREATE_BARRIER,		/* next P_DATA is preceded by a P_BARRIER */
	UNPLUG_QUEUED,		/* only relevant with kernel 2.4 */
	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. */
	NO_BARRIER_SUPP,	/* underlying block device doesn't implement barriers */
	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 */
	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) */
};

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 = 0x7,

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

	/* (test bit, count bit) allowed (common case) */
	BM_LOCKED_TEST_ALLOWED = 0x3,

	/* 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 = 0x1,

	/* clear is not expected while bitmap is locked for bulk operation */
};


/* TODO sort members for performance
 * MAYBE group them further */

/* THINK maybe we actually want to use the default "event/%s" worker threads
 * or similar in linux 2.6, which uses per cpu data and threads.
 */
struct drbd_work_queue {
	struct list_head q;
	struct semaphore s; /* producers up it, worker down()s it */
	spinlock_t q_lock;  /* to protect the list. */
};

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

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

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

	s32 al_offset;	/* signed relative sector offset to al area */
	s32 bm_offset;	/* signed relative sector offset to bitmap */

	/* u32 al_nr_extents;	   important for restoring the AL
	 * is stored into  ldev->dc.al_extents, which in turn
	 * gets applied to act_log->nr_elements
	 */
};

struct drbd_backing_dev {
	struct block_device *backing_bdev;
	struct block_device *md_bdev;
	struct drbd_md md;
	struct disk_conf dc; /* The user provided config... */
	sector_t known_size; /* last known size of that backing device */
};

struct drbd_md_io {
	struct drbd_conf *mdev;
	struct completion event;
	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 {
	int *values;
	unsigned int head_index;
	unsigned int size;
};

/* flag bits per tconn */
enum {
	NET_CONGESTED,		/* The data socket is congested */
	DISCARD_CONCURRENT,	/* 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_OKAY,
	CONN_WD_ST_CHG_FAIL,
	CONFIG_PENDING,		/* serialization of (re)configuration requests.
				 * if set, also prevents the device from dying */
	OBJECT_DYING,		/* device became unconfigured,
				 * but worker thread is still handling the cleanup.
				 * reconfiguring (nl_disk_conf, nl_net_conf) is dissalowed,
				 * while this is set. */
	CONN_DRY_RUN,		/* Expect disconnect after resync handshake. */
};

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 idr volumes;		/* <tconn, vnr> to mdev mapping */
	enum drbd_conns cstate;		/* Only C_STANDALONE to C_WF_REPORT_PARAMS */
	struct mutex cstate_mutex;	/* Protects graceful disconnects */

	unsigned long flags;
	struct net_conf *net_conf;	/* protected by get_net_conf() and put_net_conf() */
	atomic_t net_cnt;		/* Users of net_conf */
	wait_queue_head_t net_cnt_wait;
	wait_queue_head_t ping_wait;		/* Woken upon reception of a ping, and a state change */
	struct res_opts res_opts;

	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 drbd_tl_epoch *unused_spare_tle; /* for pre-allocation */
	struct drbd_tl_epoch *newest_tle;
	struct drbd_tl_epoch *oldest_tle;
	struct list_head out_of_sequence_requests;

	struct crypto_hash *cram_hmac_tfm;
	struct crypto_hash *integrity_w_tfm; /* to be used by the worker thread */
	struct crypto_hash *integrity_r_tfm; /* to be used by the receiver thread */
	struct crypto_hash *csums_tfm;
	struct crypto_hash *verify_tfm;
	void *int_dig_out;
	void *int_dig_in;
	void *int_dig_vv;

	struct drbd_thread receiver;
	struct drbd_thread worker;
	struct drbd_thread asender;
	cpumask_var_t cpu_mask;
};

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

	/* 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;

	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_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 replys 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;

	/* where does the admin want us to start? (sector) */
	sector_t ov_start_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 drbd_epoch *current_epoch;
	spinlock_t epoch_lock;
	unsigned int epochs;
	enum write_ordering_e write_ordering;
	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 mutex md_io_mutex;	/* protects the md_io_buffer */
	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;
	int al_tr_pos;   /* position of the next transaction in the journal */
	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 */
	int rs_in_flight; /* resync sectors in flight (to proxy, in proxy and from proxy) */
	int rs_planed;    /* resync sectors already planned */
	atomic_t ap_in_flight; /* App sectors in flight (waiting for ack) */
	int peer_max_bio_size;
	int local_max_bio_size;
};

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);
}

static inline int drbd_get_data_sock(struct drbd_tconn *tconn)
{
	mutex_lock(&tconn->data.mutex);
	if (!tconn->data.socket) {
		/* Disconnected.  */
		mutex_unlock(&tconn->data.mutex);
		return -EIO;
	}
	return 0;
}

static inline void drbd_put_data_sock(struct drbd_tconn *tconn)
{
	mutex_unlock(&tconn->data.mutex);
}

/*
 * 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 drbd_free_resources(struct drbd_conf *mdev);
extern void tl_release(struct drbd_tconn *, unsigned int barrier_nr,
		       unsigned int set_size);
extern void tl_clear(struct drbd_tconn *);
extern void _tl_add_barrier(struct drbd_tconn *, struct drbd_tl_epoch *);
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);
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 _conn_send_state_req(struct drbd_tconn *, int vnr, enum drbd_packet cmd,
				union drbd_state, union drbd_state);
extern int _drbd_send_state(struct drbd_conf *mdev);
extern int drbd_send_state(struct drbd_conf *mdev);
extern int _conn_send_cmd(struct drbd_tconn *tconn, int vnr, struct socket *sock,
			  enum drbd_packet cmd, struct p_header *h, size_t size,
			  unsigned msg_flags);
extern int conn_send_cmd(struct drbd_tconn *tconn, int vnr, struct drbd_socket *sock,
			 enum drbd_packet cmd, struct p_header *h, size_t size);
extern int conn_send_cmd2(struct drbd_tconn *tconn, enum drbd_packet cmd,
			  char *data, size_t size);
extern int drbd_send_sync_param(struct drbd_conf *mdev);
extern void drbd_send_b_ack(struct drbd_conf *mdev, 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 int 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 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_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_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_bmio_set_n_write(struct drbd_conf *mdev);
extern int drbd_bmio_clear_n_write(struct drbd_conf *mdev);
extern void drbd_go_diskless(struct drbd_conf *mdev);
extern void drbd_ldev_destroy(struct drbd_conf *mdev);

/* Meta data layout
   We reserve a 128MB Block (4k aligned)
   * either at the end of the backing device
   * or on a separate meta data device. */

/* The following numbers are sectors */
/* Allows up to about 3.8TB, so if you want more,
 * you need to use the "flexible" meta data format. */
#define MD_RESERVED_SECT (128LU << 11)  /* 128 MB, unit sectors */
#define MD_AL_OFFSET	8    /* 8 Sectors after start of meta area */
#define MD_AL_SECTORS	64   /* = 32 kB on disk activity log ring buffer */
#define MD_BM_OFFSET (MD_AL_OFFSET + MD_AL_SECTORS)

/* we do all meta data IO in 4k blocks */
#define MD_BLOCK_SHIFT	12
#define MD_BLOCK_SIZE	(1<<MD_BLOCK_SHIFT)

/* 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_WORDS_PER_AL_EXT (1 << (AL_EXTENT_SHIFT-BM_BLOCK_SHIFT-LN2_BPL))

#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)
#define DRBD_MAX_SECTORS_BM \
	  ((MD_RESERVED_SECT - MD_BM_OFFSET) * (1LL<<(BM_EXT_SHIFT-9)))
#if DRBD_MAX_SECTORS_BM < DRBD_MAX_SECTORS_32
#define DRBD_MAX_SECTORS      DRBD_MAX_SECTORS_BM
#define DRBD_MAX_SECTORS_FLEX DRBD_MAX_SECTORS_BM
#elif !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_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

#define HT_SHIFT 8
#define DRBD_MAX_BIO_SIZE (1U<<(9+HT_SHIFT))
#define DRBD_MAX_BIO_SIZE_SAFE (1 << 12)       /* Works always = 4k */

#define DRBD_MAX_SIZE_H80_PACKET (1 << 15) /* The old header only allows packets up to 32Kib data */

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 unsigned long drbd_bm_ALe_set_all(struct drbd_conf *mdev,
		unsigned long al_enr);
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_free_mdev(struct drbd_conf *mdev);
extern void drbd_delete_device(unsigned int minor);

struct drbd_tconn *drbd_new_tconn(const char *name);
extern void drbd_free_tconn(struct drbd_tconn *tconn);
struct drbd_tconn *conn_by_name(const char *name);

extern int proc_details;

/* drbd_req */
extern int __drbd_make_request(struct drbd_conf *, struct bio *, unsigned long);
extern int 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 *, 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 enum drbd_disk_state drbd_try_outdate_peer(struct drbd_conf *mdev);
extern void drbd_try_outdate_peer_async(struct drbd_conf *mdev);
extern int drbd_khelper(struct drbd_conf *mdev, char *cmd);

/* drbd_worker.c */
extern int drbd_worker(struct drbd_thread *thi);
extern int drbd_alter_sa(struct drbd_conf *mdev, int na);
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 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 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_read_retry_remote(struct drbd_work *, int);
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_barrier(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_release_ee(struct drbd_conf *mdev, struct list_head *list);
extern struct drbd_peer_request *drbd_alloc_ee(struct drbd_conf *,
					       u64, sector_t, unsigned int,
					       gfp_t) __must_hold(local);
extern void drbd_free_some_ee(struct drbd_conf *, struct drbd_peer_request *,
			      int);
#define drbd_free_ee(m,e)	drbd_free_some_ee(m, e, 0)
#define drbd_free_net_ee(m,e)	drbd_free_some_ee(m, e, 1)
extern void drbd_wait_ee_list_empty(struct drbd_conf *mdev,
		struct list_head *head);
extern void _drbd_wait_ee_list_empty(struct drbd_conf *mdev,
		struct list_head *head);
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(int vnr, void *p, void *data);
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. we don't need to
 * mess with get_fs/set_fs, we know we are KERNEL_DS always. */
static inline int drbd_setsockopt(struct socket *sock, int level, int optname,
			char __user *optval, int optlen)
{
	int err;
	if (level == SOL_SOCKET)
		err = sock_setsockopt(sock, level, optname, optval, optlen);
	else
		err = sock->ops->setsockopt(sock, level, optname, optval,
					    optlen);
	return err;
}

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

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

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

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

void drbd_bump_write_ordering(struct drbd_conf *mdev, 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 void drbd_al_begin_io(struct drbd_conf *mdev, sector_t sector);
extern void drbd_al_complete_io(struct drbd_conf *mdev, sector_t sector);
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 int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *);
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_apply_to_bm(struct drbd_conf *mdev);
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_bio_has_active_page(struct bio *bio)
{
	struct bio_vec *bvec;
	int i;

	__bio_for_each_segment(bvec, bio, i, 0) {
		if (page_count(bvec->bv_page) > 1)
			return 1;
	}

	return 0;
}

static inline int drbd_ee_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;
}

#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, int forcedetach, const char *where)
{
	switch (mdev->ldev->dc.on_io_error) {
	case EP_PASS_ON:
		if (!forcedetach) {
			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 to detach case if forcedetach set */
	case EP_DETACH:
	case EP_CALL_HELPER:
		set_bit(WAS_IO_ERROR, &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, int 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->dc.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->dc.meta_dev_idx) {
	case DRBD_MD_INDEX_INTERNAL:
	case DRBD_MD_INDEX_FLEX_INT:
		return bdev->md.md_offset + MD_AL_OFFSET - 1;
	case DRBD_MD_INDEX_FLEX_EXT:
	default:
		return bdev->md.md_offset + bdev->md.md_size_sect;
	}
}

/* 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->dc.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
 * @mdev:	DRBD device.
 * @bdev:	Meta data block device.
 */
static inline sector_t drbd_md_ss__(struct drbd_conf *mdev,
				    struct drbd_backing_dev *bdev)
{
	switch (bdev->dc.meta_dev_idx) {
	default: /* external, some index */
		return MD_RESERVED_SECT * bdev->dc.meta_dev_idx;
	case DRBD_MD_INDEX_INTERNAL:
		/* with drbd08, internal meta data is always "flexible" */
	case DRBD_MD_INDEX_FLEX_INT:
		/* sizeof(struct md_on_disk_07) == 4k
		 * position: last 4k aligned block of 4k size */
		if (!bdev->backing_bdev) {
			if (__ratelimit(&drbd_ratelimit_state)) {
				dev_err(DEV, "bdev->backing_bdev==NULL\n");
				dump_stack();
			}
			return 0;
		}
		return (drbd_get_capacity(bdev->backing_bdev) & ~7ULL)
			- MD_AL_OFFSET;
	case DRBD_MD_INDEX_FLEX_EXT:
		return 0;
	}
}

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);
	up(&q->s); /* within the spinlock,
		      see comment near end of drbd_worker() */
	spin_unlock_irqrestore(&q->q_lock, flags);
}

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);
	up(&q->s); /* within the spinlock,
		      see comment near end of drbd_worker() */
	spin_unlock_irqrestore(&q->q_lock, flags);
}

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);
}

static inline int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
				  enum drbd_packet cmd, struct p_header *h, size_t size,
				  unsigned msg_flags)
{
	return _conn_send_cmd(mdev->tconn, mdev->vnr, sock, cmd, h, size, msg_flags);
}

static inline int drbd_send_cmd(struct drbd_conf *mdev, struct drbd_socket *sock,
				enum drbd_packet cmd, struct p_header *h, size_t size)
{
	return conn_send_cmd(mdev->tconn, mdev->vnr, sock, cmd, h, size);
}

static inline int drbd_send_short_cmd(struct drbd_conf *mdev,
				      enum drbd_packet cmd)
{
	struct p_header h;
	return drbd_send_cmd(mdev, &mdev->tconn->data, cmd, &h, sizeof(h));
}

extern int drbd_send_ping(struct drbd_tconn *tconn);
extern int drbd_send_ping_ack(struct drbd_tconn *tconn);

static inline int drbd_send_state_req(struct drbd_conf *mdev,
				      union drbd_state mask, union drbd_state val)
{
	return _conn_send_state_req(mdev->tconn, mdev->vnr, P_STATE_CHG_REQ, mask, val);
}

static inline int conn_send_state_req(struct drbd_tconn *tconn,
				      union drbd_state mask, union drbd_state val)
{
	enum drbd_packet cmd = tconn->agreed_pro_version < 100 ? P_STATE_CHG_REQ : P_CONN_ST_CHG_REQ;
	return _conn_send_state_req(tconn, 0, cmd, mask, val);
}

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);
}

static inline void put_net_conf(struct drbd_tconn *tconn)
{
	if (atomic_dec_and_test(&tconn->net_cnt))
		wake_up(&tconn->net_cnt_wait);
}

/**
 * get_net_conf() - Increase ref count on mdev->tconn->net_conf; Returns 0 if nothing there
 * @mdev:	DRBD device.
 *
 * You have to call put_net_conf() when finished working with mdev->tconn->net_conf.
 */
static inline int get_net_conf(struct drbd_tconn *tconn)
{
	int have_net_conf;

	atomic_inc(&tconn->net_cnt);
	have_net_conf = tconn->cstate >= C_UNCONNECTED;
	if (!have_net_conf)
		put_net_conf(tconn);
	return have_net_conf;
}

/**
 * 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. */
			drbd_go_diskless(mdev);
		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 >= (1ULL << 32) ? 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)
{
	int mxb = 1000000; /* arbitrary limit on open requests */
	if (get_net_conf(mdev->tconn)) {
		mxb = mdev->tconn->net_conf->max_buffers;
		put_net_conf(mdev->tconn);
	}
	return mxb;
}

static inline int drbd_state_is_stable(struct drbd_conf *mdev)
{
	union drbd_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:
		/* disk state is stable as well. */
		break;

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

	return 1;
}

static inline int is_susp(union drbd_state s)
{
	return s.susp || s.susp_nod || s.susp_fen;
}

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

	if (is_susp(mdev->state))
		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, int count)
{
	bool rv = false;

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

	return rv;
}

static inline void inc_ap_bio(struct drbd_conf *mdev, int count)
{
	/* 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 exeed 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, count));
}

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);
	/* 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);
	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->data.work, &mdev->bm_io_work.w);
	}
}

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

	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_KERNEL, 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