summaryrefslogtreecommitdiff
path: root/drivers/block/drbd/drbd_main.c
blob: 7eb447d20cced7e345f1f1025410553c3c0dc97c (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
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
/*
   drbd.c

   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>.

   Thanks to Carter Burden, Bart Grantham and Gennadiy Nerubayev
   from Logicworks, Inc. for making SDP replication support possible.

   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.

 */

#include <linux/module.h>
#include <linux/drbd.h>
#include <asm/uaccess.h>
#include <asm/types.h>
#include <net/sock.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/memcontrol.h>
#include <linux/mm_inline.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/reboot.h>
#include <linux/notifier.h>
#include <linux/kthread.h>

#define __KERNEL_SYSCALLS__
#include <linux/unistd.h>
#include <linux/vmalloc.h>

#include <linux/drbd_limits.h>
#include "drbd_int.h"
#include "drbd_req.h" /* only for _req_mod in tl_release and tl_clear */

#include "drbd_vli.h"

struct after_state_chg_work {
	struct drbd_work w;
	union drbd_state os;
	union drbd_state ns;
	enum chg_state_flags flags;
	struct completion *done;
};

static DEFINE_MUTEX(drbd_main_mutex);
int drbdd_init(struct drbd_thread *);
int drbd_worker(struct drbd_thread *);
int drbd_asender(struct drbd_thread *);

int drbd_init(void);
static int drbd_open(struct block_device *bdev, fmode_t mode);
static int drbd_release(struct gendisk *gd, fmode_t mode);
static int w_after_state_ch(struct drbd_conf *mdev, struct drbd_work *w, int unused);
static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
			   union drbd_state ns, enum chg_state_flags flags);
static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused);
static void md_sync_timer_fn(unsigned long data);
static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused);
static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused);

MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
	      "Lars Ellenberg <lars@linbit.com>");
MODULE_DESCRIPTION("drbd - Distributed Replicated Block Device v" REL_VERSION);
MODULE_VERSION(REL_VERSION);
MODULE_LICENSE("GPL");
MODULE_PARM_DESC(minor_count, "Maximum number of drbd devices (1-255)");
MODULE_ALIAS_BLOCKDEV_MAJOR(DRBD_MAJOR);

#include <linux/moduleparam.h>
/* allow_open_on_secondary */
MODULE_PARM_DESC(allow_oos, "DONT USE!");
/* thanks to these macros, if compiled into the kernel (not-module),
 * this becomes the boot parameter drbd.minor_count */
module_param(minor_count, uint, 0444);
module_param(disable_sendpage, bool, 0644);
module_param(allow_oos, bool, 0);
module_param(cn_idx, uint, 0444);
module_param(proc_details, int, 0644);

#ifdef CONFIG_DRBD_FAULT_INJECTION
int enable_faults;
int fault_rate;
static int fault_count;
int fault_devs;
/* bitmap of enabled faults */
module_param(enable_faults, int, 0664);
/* fault rate % value - applies to all enabled faults */
module_param(fault_rate, int, 0664);
/* count of faults inserted */
module_param(fault_count, int, 0664);
/* bitmap of devices to insert faults on */
module_param(fault_devs, int, 0644);
#endif

/* module parameter, defined */
unsigned int minor_count = 32;
int disable_sendpage;
int allow_oos;
unsigned int cn_idx = CN_IDX_DRBD;
int proc_details;       /* Detail level in proc drbd*/

/* Module parameter for setting the user mode helper program
 * to run. Default is /sbin/drbdadm */
char usermode_helper[80] = "/sbin/drbdadm";

module_param_string(usermode_helper, usermode_helper, sizeof(usermode_helper), 0644);

/* in 2.6.x, our device mapping and config info contains our virtual gendisks
 * as member "struct gendisk *vdisk;"
 */
struct drbd_conf **minor_table;

struct kmem_cache *drbd_request_cache;
struct kmem_cache *drbd_ee_cache;	/* epoch entries */
struct kmem_cache *drbd_bm_ext_cache;	/* bitmap extents */
struct kmem_cache *drbd_al_ext_cache;	/* activity log extents */
mempool_t *drbd_request_mempool;
mempool_t *drbd_ee_mempool;

/* I do not use a standard mempool, because:
   1) I want to hand out the pre-allocated objects first.
   2) I want to be able to interrupt sleeping allocation with a signal.
   Note: This is a single linked list, the next pointer is the private
	 member of struct page.
 */
struct page *drbd_pp_pool;
spinlock_t   drbd_pp_lock;
int          drbd_pp_vacant;
wait_queue_head_t drbd_pp_wait;

DEFINE_RATELIMIT_STATE(drbd_ratelimit_state, 5 * HZ, 5);

static const struct block_device_operations drbd_ops = {
	.owner =   THIS_MODULE,
	.open =    drbd_open,
	.release = drbd_release,
};

#define ARRY_SIZE(A) (sizeof(A)/sizeof(A[0]))

#ifdef __CHECKER__
/* When checking with sparse, and this is an inline function, sparse will
   give tons of false positives. When this is a real functions sparse works.
 */
int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins)
{
	int io_allowed;

	atomic_inc(&mdev->local_cnt);
	io_allowed = (mdev->state.disk >= mins);
	if (!io_allowed) {
		if (atomic_dec_and_test(&mdev->local_cnt))
			wake_up(&mdev->misc_wait);
	}
	return io_allowed;
}

#endif

/**
 * DOC: The transfer log
 *
 * The transfer log is a single linked list of &struct drbd_tl_epoch objects.
 * mdev->newest_tle points to the head, mdev->oldest_tle points to the tail
 * of the list. There is always at least one &struct drbd_tl_epoch object.
 *
 * Each &struct drbd_tl_epoch has a circular double linked list of requests
 * attached.
 */
static int tl_init(struct drbd_conf *mdev)
{
	struct drbd_tl_epoch *b;

	/* during device minor initialization, we may well use GFP_KERNEL */
	b = kmalloc(sizeof(struct drbd_tl_epoch), GFP_KERNEL);
	if (!b)
		return 0;
	INIT_LIST_HEAD(&b->requests);
	INIT_LIST_HEAD(&b->w.list);
	b->next = NULL;
	b->br_number = 4711;
	b->n_writes = 0;
	b->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */

	mdev->oldest_tle = b;
	mdev->newest_tle = b;
	INIT_LIST_HEAD(&mdev->out_of_sequence_requests);

	mdev->tl_hash = NULL;
	mdev->tl_hash_s = 0;

	return 1;
}

static void tl_cleanup(struct drbd_conf *mdev)
{
	D_ASSERT(mdev->oldest_tle == mdev->newest_tle);
	D_ASSERT(list_empty(&mdev->out_of_sequence_requests));
	kfree(mdev->oldest_tle);
	mdev->oldest_tle = NULL;
	kfree(mdev->unused_spare_tle);
	mdev->unused_spare_tle = NULL;
	kfree(mdev->tl_hash);
	mdev->tl_hash = NULL;
	mdev->tl_hash_s = 0;
}

/**
 * _tl_add_barrier() - Adds a barrier to the transfer log
 * @mdev:	DRBD device.
 * @new:	Barrier to be added before the current head of the TL.
 *
 * The caller must hold the req_lock.
 */
void _tl_add_barrier(struct drbd_conf *mdev, struct drbd_tl_epoch *new)
{
	struct drbd_tl_epoch *newest_before;

	INIT_LIST_HEAD(&new->requests);
	INIT_LIST_HEAD(&new->w.list);
	new->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */
	new->next = NULL;
	new->n_writes = 0;

	newest_before = mdev->newest_tle;
	/* never send a barrier number == 0, because that is special-cased
	 * when using TCQ for our write ordering code */
	new->br_number = (newest_before->br_number+1) ?: 1;
	if (mdev->newest_tle != new) {
		mdev->newest_tle->next = new;
		mdev->newest_tle = new;
	}
}

/**
 * tl_release() - Free or recycle the oldest &struct drbd_tl_epoch object of the TL
 * @mdev:	DRBD device.
 * @barrier_nr:	Expected identifier of the DRBD write barrier packet.
 * @set_size:	Expected number of requests before that barrier.
 *
 * In case the passed barrier_nr or set_size does not match the oldest
 * &struct drbd_tl_epoch objects this function will cause a termination
 * of the connection.
 */
void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
		       unsigned int set_size)
{
	struct drbd_tl_epoch *b, *nob; /* next old barrier */
	struct list_head *le, *tle;
	struct drbd_request *r;

	spin_lock_irq(&mdev->req_lock);

	b = mdev->oldest_tle;

	/* first some paranoia code */
	if (b == NULL) {
		dev_err(DEV, "BAD! BarrierAck #%u received, but no epoch in tl!?\n",
			barrier_nr);
		goto bail;
	}
	if (b->br_number != barrier_nr) {
		dev_err(DEV, "BAD! BarrierAck #%u received, expected #%u!\n",
			barrier_nr, b->br_number);
		goto bail;
	}
	if (b->n_writes != set_size) {
		dev_err(DEV, "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n",
			barrier_nr, set_size, b->n_writes);
		goto bail;
	}

	/* Clean up list of requests processed during current epoch */
	list_for_each_safe(le, tle, &b->requests) {
		r = list_entry(le, struct drbd_request, tl_requests);
		_req_mod(r, barrier_acked);
	}
	/* There could be requests on the list waiting for completion
	   of the write to the local disk. To avoid corruptions of
	   slab's data structures we have to remove the lists head.

	   Also there could have been a barrier ack out of sequence, overtaking
	   the write acks - which would be a bug and violating write ordering.
	   To not deadlock in case we lose connection while such requests are
	   still pending, we need some way to find them for the
	   _req_mode(connection_lost_while_pending).

	   These have been list_move'd to the out_of_sequence_requests list in
	   _req_mod(, barrier_acked) above.
	   */
	list_del_init(&b->requests);

	nob = b->next;
	if (test_and_clear_bit(CREATE_BARRIER, &mdev->flags)) {
		_tl_add_barrier(mdev, b);
		if (nob)
			mdev->oldest_tle = nob;
		/* if nob == NULL b was the only barrier, and becomes the new
		   barrier. Therefore mdev->oldest_tle points already to b */
	} else {
		D_ASSERT(nob != NULL);
		mdev->oldest_tle = nob;
		kfree(b);
	}

	spin_unlock_irq(&mdev->req_lock);
	dec_ap_pending(mdev);

	return;

bail:
	spin_unlock_irq(&mdev->req_lock);
	drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
}

/**
 * _tl_restart() - Walks the transfer log, and applies an action to all requests
 * @mdev:	DRBD device.
 * @what:       The action/event to perform with all request objects
 *
 * @what might be one of connection_lost_while_pending, resend, fail_frozen_disk_io,
 * restart_frozen_disk_io.
 */
static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
{
	struct drbd_tl_epoch *b, *tmp, **pn;
	struct list_head *le, *tle, carry_reads;
	struct drbd_request *req;
	int rv, n_writes, n_reads;

	b = mdev->oldest_tle;
	pn = &mdev->oldest_tle;
	while (b) {
		n_writes = 0;
		n_reads = 0;
		INIT_LIST_HEAD(&carry_reads);
		list_for_each_safe(le, tle, &b->requests) {
			req = list_entry(le, struct drbd_request, tl_requests);
			rv = _req_mod(req, what);

			n_writes += (rv & MR_WRITE) >> MR_WRITE_SHIFT;
			n_reads  += (rv & MR_READ) >> MR_READ_SHIFT;
		}
		tmp = b->next;

		if (n_writes) {
			if (what == resend) {
				b->n_writes = n_writes;
				if (b->w.cb == NULL) {
					b->w.cb = w_send_barrier;
					inc_ap_pending(mdev);
					set_bit(CREATE_BARRIER, &mdev->flags);
				}

				drbd_queue_work(&mdev->data.work, &b->w);
			}
			pn = &b->next;
		} else {
			if (n_reads)
				list_add(&carry_reads, &b->requests);
			/* there could still be requests on that ring list,
			 * in case local io is still pending */
			list_del(&b->requests);

			/* dec_ap_pending corresponding to queue_barrier.
			 * the newest barrier may not have been queued yet,
			 * in which case w.cb is still NULL. */
			if (b->w.cb != NULL)
				dec_ap_pending(mdev);

			if (b == mdev->newest_tle) {
				/* recycle, but reinit! */
				D_ASSERT(tmp == NULL);
				INIT_LIST_HEAD(&b->requests);
				list_splice(&carry_reads, &b->requests);
				INIT_LIST_HEAD(&b->w.list);
				b->w.cb = NULL;
				b->br_number = net_random();
				b->n_writes = 0;

				*pn = b;
				break;
			}
			*pn = tmp;
			kfree(b);
		}
		b = tmp;
		list_splice(&carry_reads, &b->requests);
	}
}


/**
 * tl_clear() - Clears all requests and &struct drbd_tl_epoch objects out of the TL
 * @mdev:	DRBD device.
 *
 * This is called after the connection to the peer was lost. The storage covered
 * by the requests on the transfer gets marked as our of sync. Called from the
 * receiver thread and the worker thread.
 */
void tl_clear(struct drbd_conf *mdev)
{
	struct list_head *le, *tle;
	struct drbd_request *r;

	spin_lock_irq(&mdev->req_lock);

	_tl_restart(mdev, connection_lost_while_pending);

	/* we expect this list to be empty. */
	D_ASSERT(list_empty(&mdev->out_of_sequence_requests));

	/* but just in case, clean it up anyways! */
	list_for_each_safe(le, tle, &mdev->out_of_sequence_requests) {
		r = list_entry(le, struct drbd_request, tl_requests);
		/* It would be nice to complete outside of spinlock.
		 * But this is easier for now. */
		_req_mod(r, connection_lost_while_pending);
	}

	/* ensure bit indicating barrier is required is clear */
	clear_bit(CREATE_BARRIER, &mdev->flags);

	memset(mdev->app_reads_hash, 0, APP_R_HSIZE*sizeof(void *));

	spin_unlock_irq(&mdev->req_lock);
}

void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
{
	spin_lock_irq(&mdev->req_lock);
	_tl_restart(mdev, what);
	spin_unlock_irq(&mdev->req_lock);
}

/**
 * cl_wide_st_chg() - true if the state change is a cluster wide one
 * @mdev:	DRBD device.
 * @os:		old (current) state.
 * @ns:		new (wanted) state.
 */
static int cl_wide_st_chg(struct drbd_conf *mdev,
			  union drbd_state os, union drbd_state ns)
{
	return (os.conn >= C_CONNECTED && ns.conn >= C_CONNECTED &&
		 ((os.role != R_PRIMARY && ns.role == R_PRIMARY) ||
		  (os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
		  (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S) ||
		  (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))) ||
		(os.conn >= C_CONNECTED && ns.conn == C_DISCONNECTING) ||
		(os.conn == C_CONNECTED && ns.conn == C_VERIFY_S);
}

enum drbd_state_rv
drbd_change_state(struct drbd_conf *mdev, enum chg_state_flags f,
		  union drbd_state mask, union drbd_state val)
{
	unsigned long flags;
	union drbd_state os, ns;
	enum drbd_state_rv rv;

	spin_lock_irqsave(&mdev->req_lock, flags);
	os = mdev->state;
	ns.i = (os.i & ~mask.i) | val.i;
	rv = _drbd_set_state(mdev, ns, f, NULL);
	ns = mdev->state;
	spin_unlock_irqrestore(&mdev->req_lock, flags);

	return rv;
}

/**
 * drbd_force_state() - Impose a change which happens outside our control on our state
 * @mdev:	DRBD device.
 * @mask:	mask of state bits to change.
 * @val:	value of new state bits.
 */
void drbd_force_state(struct drbd_conf *mdev,
	union drbd_state mask, union drbd_state val)
{
	drbd_change_state(mdev, CS_HARD, mask, val);
}

static enum drbd_state_rv is_valid_state(struct drbd_conf *, union drbd_state);
static enum drbd_state_rv is_valid_state_transition(struct drbd_conf *,
						    union drbd_state,
						    union drbd_state);
static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
				       union drbd_state ns, const char **warn_sync_abort);
int drbd_send_state_req(struct drbd_conf *,
			union drbd_state, union drbd_state);

static enum drbd_state_rv
_req_st_cond(struct drbd_conf *mdev, union drbd_state mask,
	     union drbd_state val)
{
	union drbd_state os, ns;
	unsigned long flags;
	enum drbd_state_rv rv;

	if (test_and_clear_bit(CL_ST_CHG_SUCCESS, &mdev->flags))
		return SS_CW_SUCCESS;

	if (test_and_clear_bit(CL_ST_CHG_FAIL, &mdev->flags))
		return SS_CW_FAILED_BY_PEER;

	rv = 0;
	spin_lock_irqsave(&mdev->req_lock, flags);
	os = mdev->state;
	ns.i = (os.i & ~mask.i) | val.i;
	ns = sanitize_state(mdev, os, ns, NULL);

	if (!cl_wide_st_chg(mdev, os, ns))
		rv = SS_CW_NO_NEED;
	if (!rv) {
		rv = is_valid_state(mdev, ns);
		if (rv == SS_SUCCESS) {
			rv = is_valid_state_transition(mdev, ns, os);
			if (rv == SS_SUCCESS)
				rv = SS_UNKNOWN_ERROR; /* cont waiting, otherwise fail. */
		}
	}
	spin_unlock_irqrestore(&mdev->req_lock, flags);

	return rv;
}

/**
 * drbd_req_state() - Perform an eventually cluster wide state change
 * @mdev:	DRBD device.
 * @mask:	mask of state bits to change.
 * @val:	value of new state bits.
 * @f:		flags
 *
 * Should not be called directly, use drbd_request_state() or
 * _drbd_request_state().
 */
static enum drbd_state_rv
drbd_req_state(struct drbd_conf *mdev, union drbd_state mask,
	       union drbd_state val, enum chg_state_flags f)
{
	struct completion done;
	unsigned long flags;
	union drbd_state os, ns;
	enum drbd_state_rv rv;

	init_completion(&done);

	if (f & CS_SERIALIZE)
		mutex_lock(&mdev->state_mutex);

	spin_lock_irqsave(&mdev->req_lock, flags);
	os = mdev->state;
	ns.i = (os.i & ~mask.i) | val.i;
	ns = sanitize_state(mdev, os, ns, NULL);

	if (cl_wide_st_chg(mdev, os, ns)) {
		rv = is_valid_state(mdev, ns);
		if (rv == SS_SUCCESS)
			rv = is_valid_state_transition(mdev, ns, os);
		spin_unlock_irqrestore(&mdev->req_lock, flags);

		if (rv < SS_SUCCESS) {
			if (f & CS_VERBOSE)
				print_st_err(mdev, os, ns, rv);
			goto abort;
		}

		drbd_state_lock(mdev);
		if (!drbd_send_state_req(mdev, mask, val)) {
			drbd_state_unlock(mdev);
			rv = SS_CW_FAILED_BY_PEER;
			if (f & CS_VERBOSE)
				print_st_err(mdev, os, ns, rv);
			goto abort;
		}

		wait_event(mdev->state_wait,
			(rv = _req_st_cond(mdev, mask, val)));

		if (rv < SS_SUCCESS) {
			drbd_state_unlock(mdev);
			if (f & CS_VERBOSE)
				print_st_err(mdev, os, ns, rv);
			goto abort;
		}
		spin_lock_irqsave(&mdev->req_lock, flags);
		os = mdev->state;
		ns.i = (os.i & ~mask.i) | val.i;
		rv = _drbd_set_state(mdev, ns, f, &done);
		drbd_state_unlock(mdev);
	} else {
		rv = _drbd_set_state(mdev, ns, f, &done);
	}

	spin_unlock_irqrestore(&mdev->req_lock, flags);

	if (f & CS_WAIT_COMPLETE && rv == SS_SUCCESS) {
		D_ASSERT(current != mdev->worker.task);
		wait_for_completion(&done);
	}

abort:
	if (f & CS_SERIALIZE)
		mutex_unlock(&mdev->state_mutex);

	return rv;
}

/**
 * _drbd_request_state() - Request a state change (with flags)
 * @mdev:	DRBD device.
 * @mask:	mask of state bits to change.
 * @val:	value of new state bits.
 * @f:		flags
 *
 * Cousin of drbd_request_state(), useful with the CS_WAIT_COMPLETE
 * flag, or when logging of failed state change requests is not desired.
 */
enum drbd_state_rv
_drbd_request_state(struct drbd_conf *mdev, union drbd_state mask,
		    union drbd_state val, enum chg_state_flags f)
{
	enum drbd_state_rv rv;

	wait_event(mdev->state_wait,
		   (rv = drbd_req_state(mdev, mask, val, f)) != SS_IN_TRANSIENT_STATE);

	return rv;
}

static void print_st(struct drbd_conf *mdev, char *name, union drbd_state ns)
{
	dev_err(DEV, " %s = { cs:%s ro:%s/%s ds:%s/%s %c%c%c%c }\n",
	    name,
	    drbd_conn_str(ns.conn),
	    drbd_role_str(ns.role),
	    drbd_role_str(ns.peer),
	    drbd_disk_str(ns.disk),
	    drbd_disk_str(ns.pdsk),
	    is_susp(ns) ? 's' : 'r',
	    ns.aftr_isp ? 'a' : '-',
	    ns.peer_isp ? 'p' : '-',
	    ns.user_isp ? 'u' : '-'
	    );
}

void print_st_err(struct drbd_conf *mdev, union drbd_state os,
	          union drbd_state ns, enum drbd_state_rv err)
{
	if (err == SS_IN_TRANSIENT_STATE)
		return;
	dev_err(DEV, "State change failed: %s\n", drbd_set_st_err_str(err));
	print_st(mdev, " state", os);
	print_st(mdev, "wanted", ns);
}


/**
 * is_valid_state() - Returns an SS_ error code if ns is not valid
 * @mdev:	DRBD device.
 * @ns:		State to consider.
 */
static enum drbd_state_rv
is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
{
	/* See drbd_state_sw_errors in drbd_strings.c */

	enum drbd_fencing_p fp;
	enum drbd_state_rv rv = SS_SUCCESS;

	fp = FP_DONT_CARE;
	if (get_ldev(mdev)) {
		fp = mdev->ldev->dc.fencing;
		put_ldev(mdev);
	}

	if (get_net_conf(mdev)) {
		if (!mdev->net_conf->two_primaries &&
		    ns.role == R_PRIMARY && ns.peer == R_PRIMARY)
			rv = SS_TWO_PRIMARIES;
		put_net_conf(mdev);
	}

	if (rv <= 0)
		/* already found a reason to abort */;
	else if (ns.role == R_SECONDARY && mdev->open_cnt)
		rv = SS_DEVICE_IN_USE;

	else if (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.disk < D_UP_TO_DATE)
		rv = SS_NO_UP_TO_DATE_DISK;

	else if (fp >= FP_RESOURCE &&
		 ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk >= D_UNKNOWN)
		rv = SS_PRIMARY_NOP;

	else if (ns.role == R_PRIMARY && ns.disk <= D_INCONSISTENT && ns.pdsk <= D_INCONSISTENT)
		rv = SS_NO_UP_TO_DATE_DISK;

	else if (ns.conn > C_CONNECTED && ns.disk < D_INCONSISTENT)
		rv = SS_NO_LOCAL_DISK;

	else if (ns.conn > C_CONNECTED && ns.pdsk < D_INCONSISTENT)
		rv = SS_NO_REMOTE_DISK;

	else if (ns.conn > C_CONNECTED && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE)
		rv = SS_NO_UP_TO_DATE_DISK;

	else if ((ns.conn == C_CONNECTED ||
		  ns.conn == C_WF_BITMAP_S ||
		  ns.conn == C_SYNC_SOURCE ||
		  ns.conn == C_PAUSED_SYNC_S) &&
		  ns.disk == D_OUTDATED)
		rv = SS_CONNECTED_OUTDATES;

	else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
		 (mdev->sync_conf.verify_alg[0] == 0))
		rv = SS_NO_VERIFY_ALG;

	else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
		  mdev->agreed_pro_version < 88)
		rv = SS_NOT_SUPPORTED;

	return rv;
}

/**
 * is_valid_state_transition() - Returns an SS_ error code if the state transition is not possible
 * @mdev:	DRBD device.
 * @ns:		new state.
 * @os:		old state.
 */
static enum drbd_state_rv
is_valid_state_transition(struct drbd_conf *mdev, union drbd_state ns,
			  union drbd_state os)
{
	enum drbd_state_rv rv = SS_SUCCESS;

	if ((ns.conn == C_STARTING_SYNC_T || ns.conn == C_STARTING_SYNC_S) &&
	    os.conn > C_CONNECTED)
		rv = SS_RESYNC_RUNNING;

	if (ns.conn == C_DISCONNECTING && os.conn == C_STANDALONE)
		rv = SS_ALREADY_STANDALONE;

	if (ns.disk > D_ATTACHING && os.disk == D_DISKLESS)
		rv = SS_IS_DISKLESS;

	if (ns.conn == C_WF_CONNECTION && os.conn < C_UNCONNECTED)
		rv = SS_NO_NET_CONFIG;

	if (ns.disk == D_OUTDATED && os.disk < D_OUTDATED && os.disk != D_ATTACHING)
		rv = SS_LOWER_THAN_OUTDATED;

	if (ns.conn == C_DISCONNECTING && os.conn == C_UNCONNECTED)
		rv = SS_IN_TRANSIENT_STATE;

	if (ns.conn == os.conn && ns.conn == C_WF_REPORT_PARAMS)
		rv = SS_IN_TRANSIENT_STATE;

	if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
		rv = SS_NEED_CONNECTION;

	if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
	    ns.conn != os.conn && os.conn > C_CONNECTED)
		rv = SS_RESYNC_RUNNING;

	if ((ns.conn == C_STARTING_SYNC_S || ns.conn == C_STARTING_SYNC_T) &&
	    os.conn < C_CONNECTED)
		rv = SS_NEED_CONNECTION;

	if ((ns.conn == C_SYNC_TARGET || ns.conn == C_SYNC_SOURCE)
	    && os.conn < C_WF_REPORT_PARAMS)
		rv = SS_NEED_CONNECTION; /* No NetworkFailure -> SyncTarget etc... */

	return rv;
}

/**
 * sanitize_state() - Resolves implicitly necessary additional changes to a state transition
 * @mdev:	DRBD device.
 * @os:		old state.
 * @ns:		new state.
 * @warn_sync_abort:
 *
 * When we loose connection, we have to set the state of the peers disk (pdsk)
 * to D_UNKNOWN. This rule and many more along those lines are in this function.
 */
static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
				       union drbd_state ns, const char **warn_sync_abort)
{
	enum drbd_fencing_p fp;
	enum drbd_disk_state disk_min, disk_max, pdsk_min, pdsk_max;

	fp = FP_DONT_CARE;
	if (get_ldev(mdev)) {
		fp = mdev->ldev->dc.fencing;
		put_ldev(mdev);
	}

	/* Disallow Network errors to configure a device's network part */
	if ((ns.conn >= C_TIMEOUT && ns.conn <= C_TEAR_DOWN) &&
	    os.conn <= C_DISCONNECTING)
		ns.conn = os.conn;

	/* After a network error (+C_TEAR_DOWN) only C_UNCONNECTED or C_DISCONNECTING can follow.
	 * If you try to go into some Sync* state, that shall fail (elsewhere). */
	if (os.conn >= C_TIMEOUT && os.conn <= C_TEAR_DOWN &&
	    ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_TEAR_DOWN)
		ns.conn = os.conn;

	/* we cannot fail (again) if we already detached */
	if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
		ns.disk = D_DISKLESS;

	/* if we are only D_ATTACHING yet,
	 * we can (and should) go directly to D_DISKLESS. */
	if (ns.disk == D_FAILED && os.disk == D_ATTACHING)
		ns.disk = D_DISKLESS;

	/* After C_DISCONNECTING only C_STANDALONE may follow */
	if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
		ns.conn = os.conn;

	if (ns.conn < C_CONNECTED) {
		ns.peer_isp = 0;
		ns.peer = R_UNKNOWN;
		if (ns.pdsk > D_UNKNOWN || ns.pdsk < D_INCONSISTENT)
			ns.pdsk = D_UNKNOWN;
	}

	/* Clear the aftr_isp when becoming unconfigured */
	if (ns.conn == C_STANDALONE && ns.disk == D_DISKLESS && ns.role == R_SECONDARY)
		ns.aftr_isp = 0;

	/* Abort resync if a disk fails/detaches */
	if (os.conn > C_CONNECTED && ns.conn > C_CONNECTED &&
	    (ns.disk <= D_FAILED || ns.pdsk <= D_FAILED)) {
		if (warn_sync_abort)
			*warn_sync_abort =
				os.conn == C_VERIFY_S || os.conn == C_VERIFY_T ?
				"Online-verify" : "Resync";
		ns.conn = C_CONNECTED;
	}

	/* Connection breaks down before we finished "Negotiating" */
	if (ns.conn < C_CONNECTED && ns.disk == D_NEGOTIATING &&
	    get_ldev_if_state(mdev, D_NEGOTIATING)) {
		if (mdev->ed_uuid == mdev->ldev->md.uuid[UI_CURRENT]) {
			ns.disk = mdev->new_state_tmp.disk;
			ns.pdsk = mdev->new_state_tmp.pdsk;
		} else {
			dev_alert(DEV, "Connection lost while negotiating, no data!\n");
			ns.disk = D_DISKLESS;
			ns.pdsk = D_UNKNOWN;
		}
		put_ldev(mdev);
	}

	/* D_CONSISTENT and D_OUTDATED vanish when we get connected */
	if (ns.conn >= C_CONNECTED && ns.conn < C_AHEAD) {
		if (ns.disk == D_CONSISTENT || ns.disk == D_OUTDATED)
			ns.disk = D_UP_TO_DATE;
		if (ns.pdsk == D_CONSISTENT || ns.pdsk == D_OUTDATED)
			ns.pdsk = D_UP_TO_DATE;
	}

	/* Implications of the connection stat on the disk states */
	disk_min = D_DISKLESS;
	disk_max = D_UP_TO_DATE;
	pdsk_min = D_INCONSISTENT;
	pdsk_max = D_UNKNOWN;
	switch ((enum drbd_conns)ns.conn) {
	case C_WF_BITMAP_T:
	case C_PAUSED_SYNC_T:
	case C_STARTING_SYNC_T:
	case C_WF_SYNC_UUID:
	case C_BEHIND:
		disk_min = D_INCONSISTENT;
		disk_max = D_OUTDATED;
		pdsk_min = D_UP_TO_DATE;
		pdsk_max = D_UP_TO_DATE;
		break;
	case C_VERIFY_S:
	case C_VERIFY_T:
		disk_min = D_UP_TO_DATE;
		disk_max = D_UP_TO_DATE;
		pdsk_min = D_UP_TO_DATE;
		pdsk_max = D_UP_TO_DATE;
		break;
	case C_CONNECTED:
		disk_min = D_DISKLESS;
		disk_max = D_UP_TO_DATE;
		pdsk_min = D_DISKLESS;
		pdsk_max = D_UP_TO_DATE;
		break;
	case C_WF_BITMAP_S:
	case C_PAUSED_SYNC_S:
	case C_STARTING_SYNC_S:
	case C_AHEAD:
		disk_min = D_UP_TO_DATE;
		disk_max = D_UP_TO_DATE;
		pdsk_min = D_INCONSISTENT;
		pdsk_max = D_CONSISTENT; /* D_OUTDATED would be nice. But explicit outdate necessary*/
		break;
	case C_SYNC_TARGET:
		disk_min = D_INCONSISTENT;
		disk_max = D_INCONSISTENT;
		pdsk_min = D_UP_TO_DATE;
		pdsk_max = D_UP_TO_DATE;
		break;
	case C_SYNC_SOURCE:
		disk_min = D_UP_TO_DATE;
		disk_max = D_UP_TO_DATE;
		pdsk_min = D_INCONSISTENT;
		pdsk_max = D_INCONSISTENT;
		break;
	case C_STANDALONE:
	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_CONNECTION:
	case C_WF_REPORT_PARAMS:
	case C_MASK:
		break;
	}
	if (ns.disk > disk_max)
		ns.disk = disk_max;

	if (ns.disk < disk_min) {
		dev_warn(DEV, "Implicitly set disk from %s to %s\n",
			 drbd_disk_str(ns.disk), drbd_disk_str(disk_min));
		ns.disk = disk_min;
	}
	if (ns.pdsk > pdsk_max)
		ns.pdsk = pdsk_max;

	if (ns.pdsk < pdsk_min) {
		dev_warn(DEV, "Implicitly set pdsk from %s to %s\n",
			 drbd_disk_str(ns.pdsk), drbd_disk_str(pdsk_min));
		ns.pdsk = pdsk_min;
	}

	if (fp == FP_STONITH &&
	    (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk > D_OUTDATED) &&
	    !(os.role == R_PRIMARY && os.conn < C_CONNECTED && os.pdsk > D_OUTDATED))
		ns.susp_fen = 1; /* Suspend IO while fence-peer handler runs (peer lost) */

	if (mdev->sync_conf.on_no_data == OND_SUSPEND_IO &&
	    (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE) &&
	    !(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE))
		ns.susp_nod = 1; /* Suspend IO while no data available (no accessible data available) */

	if (ns.aftr_isp || ns.peer_isp || ns.user_isp) {
		if (ns.conn == C_SYNC_SOURCE)
			ns.conn = C_PAUSED_SYNC_S;
		if (ns.conn == C_SYNC_TARGET)
			ns.conn = C_PAUSED_SYNC_T;
	} else {
		if (ns.conn == C_PAUSED_SYNC_S)
			ns.conn = C_SYNC_SOURCE;
		if (ns.conn == C_PAUSED_SYNC_T)
			ns.conn = C_SYNC_TARGET;
	}

	return ns;
}

/* helper for __drbd_set_state */
static void set_ov_position(struct drbd_conf *mdev, enum drbd_conns cs)
{
	if (mdev->agreed_pro_version < 90)
		mdev->ov_start_sector = 0;
	mdev->rs_total = drbd_bm_bits(mdev);
	mdev->ov_position = 0;
	if (cs == C_VERIFY_T) {
		/* starting online verify from an arbitrary position
		 * does not fit well into the existing protocol.
		 * on C_VERIFY_T, we initialize ov_left and friends
		 * implicitly in receive_DataRequest once the
		 * first P_OV_REQUEST is received */
		mdev->ov_start_sector = ~(sector_t)0;
	} else {
		unsigned long bit = BM_SECT_TO_BIT(mdev->ov_start_sector);
		if (bit >= mdev->rs_total) {
			mdev->ov_start_sector =
				BM_BIT_TO_SECT(mdev->rs_total - 1);
			mdev->rs_total = 1;
		} else
			mdev->rs_total -= bit;
		mdev->ov_position = mdev->ov_start_sector;
	}
	mdev->ov_left = mdev->rs_total;
}

static void drbd_resume_al(struct drbd_conf *mdev)
{
	if (test_and_clear_bit(AL_SUSPENDED, &mdev->flags))
		dev_info(DEV, "Resumed AL updates\n");
}

/**
 * __drbd_set_state() - Set a new DRBD state
 * @mdev:	DRBD device.
 * @ns:		new state.
 * @flags:	Flags
 * @done:	Optional completion, that will get completed after the after_state_ch() finished
 *
 * Caller needs to hold req_lock, and global_state_lock. Do not call directly.
 */
enum drbd_state_rv
__drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
	         enum chg_state_flags flags, struct completion *done)
{
	union drbd_state os;
	enum drbd_state_rv rv = SS_SUCCESS;
	const char *warn_sync_abort = NULL;
	struct after_state_chg_work *ascw;

	os = mdev->state;

	ns = sanitize_state(mdev, os, ns, &warn_sync_abort);

	if (ns.i == os.i)
		return SS_NOTHING_TO_DO;

	if (!(flags & CS_HARD)) {
		/*  pre-state-change checks ; only look at ns  */
		/* See drbd_state_sw_errors in drbd_strings.c */

		rv = is_valid_state(mdev, ns);
		if (rv < SS_SUCCESS) {
			/* If the old state was illegal as well, then let
			   this happen...*/

			if (is_valid_state(mdev, os) == rv)
				rv = is_valid_state_transition(mdev, ns, os);
		} else
			rv = is_valid_state_transition(mdev, ns, os);
	}

	if (rv < SS_SUCCESS) {
		if (flags & CS_VERBOSE)
			print_st_err(mdev, os, ns, rv);
		return rv;
	}

	if (warn_sync_abort)
		dev_warn(DEV, "%s aborted.\n", warn_sync_abort);

	{
	char *pbp, pb[300];
	pbp = pb;
	*pbp = 0;
	if (ns.role != os.role)
		pbp += sprintf(pbp, "role( %s -> %s ) ",
			       drbd_role_str(os.role),
			       drbd_role_str(ns.role));
	if (ns.peer != os.peer)
		pbp += sprintf(pbp, "peer( %s -> %s ) ",
			       drbd_role_str(os.peer),
			       drbd_role_str(ns.peer));
	if (ns.conn != os.conn)
		pbp += sprintf(pbp, "conn( %s -> %s ) ",
			       drbd_conn_str(os.conn),
			       drbd_conn_str(ns.conn));
	if (ns.disk != os.disk)
		pbp += sprintf(pbp, "disk( %s -> %s ) ",
			       drbd_disk_str(os.disk),
			       drbd_disk_str(ns.disk));
	if (ns.pdsk != os.pdsk)
		pbp += sprintf(pbp, "pdsk( %s -> %s ) ",
			       drbd_disk_str(os.pdsk),
			       drbd_disk_str(ns.pdsk));
	if (is_susp(ns) != is_susp(os))
		pbp += sprintf(pbp, "susp( %d -> %d ) ",
			       is_susp(os),
			       is_susp(ns));
	if (ns.aftr_isp != os.aftr_isp)
		pbp += sprintf(pbp, "aftr_isp( %d -> %d ) ",
			       os.aftr_isp,
			       ns.aftr_isp);
	if (ns.peer_isp != os.peer_isp)
		pbp += sprintf(pbp, "peer_isp( %d -> %d ) ",
			       os.peer_isp,
			       ns.peer_isp);
	if (ns.user_isp != os.user_isp)
		pbp += sprintf(pbp, "user_isp( %d -> %d ) ",
			       os.user_isp,
			       ns.user_isp);
	dev_info(DEV, "%s\n", pb);
	}

	/* solve the race between becoming unconfigured,
	 * worker doing the cleanup, and
	 * admin reconfiguring us:
	 * on (re)configure, first set CONFIG_PENDING,
	 * then wait for a potentially exiting worker,
	 * start the worker, and schedule one no_op.
	 * then proceed with configuration.
	 */
	if (ns.disk == D_DISKLESS &&
	    ns.conn == C_STANDALONE &&
	    ns.role == R_SECONDARY &&
	    !test_and_set_bit(CONFIG_PENDING, &mdev->flags))
		set_bit(DEVICE_DYING, &mdev->flags);

	/* if we are going -> D_FAILED or D_DISKLESS, grab one extra reference
	 * on the ldev here, to be sure the transition -> D_DISKLESS resp.
	 * drbd_ldev_destroy() won't happen before our corresponding
	 * after_state_ch works run, where we put_ldev again. */
	if ((os.disk != D_FAILED && ns.disk == D_FAILED) ||
	    (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))
		atomic_inc(&mdev->local_cnt);

	mdev->state = ns;
	wake_up(&mdev->misc_wait);
	wake_up(&mdev->state_wait);

	/* aborted verify run. log the last position */
	if ((os.conn == C_VERIFY_S || os.conn == C_VERIFY_T) &&
	    ns.conn < C_CONNECTED) {
		mdev->ov_start_sector =
			BM_BIT_TO_SECT(drbd_bm_bits(mdev) - mdev->ov_left);
		dev_info(DEV, "Online Verify reached sector %llu\n",
			(unsigned long long)mdev->ov_start_sector);
	}

	if ((os.conn == C_PAUSED_SYNC_T || os.conn == C_PAUSED_SYNC_S) &&
	    (ns.conn == C_SYNC_TARGET  || ns.conn == C_SYNC_SOURCE)) {
		dev_info(DEV, "Syncer continues.\n");
		mdev->rs_paused += (long)jiffies
				  -(long)mdev->rs_mark_time[mdev->rs_last_mark];
		if (ns.conn == C_SYNC_TARGET)
			mod_timer(&mdev->resync_timer, jiffies);
	}

	if ((os.conn == C_SYNC_TARGET  || os.conn == C_SYNC_SOURCE) &&
	    (ns.conn == C_PAUSED_SYNC_T || ns.conn == C_PAUSED_SYNC_S)) {
		dev_info(DEV, "Resync suspended\n");
		mdev->rs_mark_time[mdev->rs_last_mark] = jiffies;
	}

	if (os.conn == C_CONNECTED &&
	    (ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T)) {
		unsigned long now = jiffies;
		int i;

		set_ov_position(mdev, ns.conn);
		mdev->rs_start = now;
		mdev->rs_last_events = 0;
		mdev->rs_last_sect_ev = 0;
		mdev->ov_last_oos_size = 0;
		mdev->ov_last_oos_start = 0;

		for (i = 0; i < DRBD_SYNC_MARKS; i++) {
			mdev->rs_mark_left[i] = mdev->ov_left;
			mdev->rs_mark_time[i] = now;
		}

		drbd_rs_controller_reset(mdev);

		if (ns.conn == C_VERIFY_S) {
			dev_info(DEV, "Starting Online Verify from sector %llu\n",
					(unsigned long long)mdev->ov_position);
			mod_timer(&mdev->resync_timer, jiffies);
		}
	}

	if (get_ldev(mdev)) {
		u32 mdf = mdev->ldev->md.flags & ~(MDF_CONSISTENT|MDF_PRIMARY_IND|
						 MDF_CONNECTED_IND|MDF_WAS_UP_TO_DATE|
						 MDF_PEER_OUT_DATED|MDF_CRASHED_PRIMARY);

		if (test_bit(CRASHED_PRIMARY, &mdev->flags))
			mdf |= MDF_CRASHED_PRIMARY;
		if (mdev->state.role == R_PRIMARY ||
		    (mdev->state.pdsk < D_INCONSISTENT && mdev->state.peer == R_PRIMARY))
			mdf |= MDF_PRIMARY_IND;
		if (mdev->state.conn > C_WF_REPORT_PARAMS)
			mdf |= MDF_CONNECTED_IND;
		if (mdev->state.disk > D_INCONSISTENT)
			mdf |= MDF_CONSISTENT;
		if (mdev->state.disk > D_OUTDATED)
			mdf |= MDF_WAS_UP_TO_DATE;
		if (mdev->state.pdsk <= D_OUTDATED && mdev->state.pdsk >= D_INCONSISTENT)
			mdf |= MDF_PEER_OUT_DATED;
		if (mdf != mdev->ldev->md.flags) {
			mdev->ldev->md.flags = mdf;
			drbd_md_mark_dirty(mdev);
		}
		if (os.disk < D_CONSISTENT && ns.disk >= D_CONSISTENT)
			drbd_set_ed_uuid(mdev, mdev->ldev->md.uuid[UI_CURRENT]);
		put_ldev(mdev);
	}

	/* Peer was forced D_UP_TO_DATE & R_PRIMARY, consider to resync */
	if (os.disk == D_INCONSISTENT && os.pdsk == D_INCONSISTENT &&
	    os.peer == R_SECONDARY && ns.peer == R_PRIMARY)
		set_bit(CONSIDER_RESYNC, &mdev->flags);

	/* Receiver should clean up itself */
	if (os.conn != C_DISCONNECTING && ns.conn == C_DISCONNECTING)
		drbd_thread_stop_nowait(&mdev->receiver);

	/* Now the receiver finished cleaning up itself, it should die */
	if (os.conn != C_STANDALONE && ns.conn == C_STANDALONE)
		drbd_thread_stop_nowait(&mdev->receiver);

	/* Upon network failure, we need to restart the receiver. */
	if (os.conn > C_TEAR_DOWN &&
	    ns.conn <= C_TEAR_DOWN && ns.conn >= C_TIMEOUT)
		drbd_thread_restart_nowait(&mdev->receiver);

	/* Resume AL writing if we get a connection */
	if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
		drbd_resume_al(mdev);

	ascw = kmalloc(sizeof(*ascw), GFP_ATOMIC);
	if (ascw) {
		ascw->os = os;
		ascw->ns = ns;
		ascw->flags = flags;
		ascw->w.cb = w_after_state_ch;
		ascw->done = done;
		drbd_queue_work(&mdev->data.work, &ascw->w);
	} else {
		dev_warn(DEV, "Could not kmalloc an ascw\n");
	}

	return rv;
}

static int w_after_state_ch(struct drbd_conf *mdev, struct drbd_work *w, int unused)
{
	struct after_state_chg_work *ascw =
		container_of(w, struct after_state_chg_work, w);
	after_state_ch(mdev, ascw->os, ascw->ns, ascw->flags);
	if (ascw->flags & CS_WAIT_COMPLETE) {
		D_ASSERT(ascw->done != NULL);
		complete(ascw->done);
	}
	kfree(ascw);

	return 1;
}

static void abw_start_sync(struct drbd_conf *mdev, int rv)
{
	if (rv) {
		dev_err(DEV, "Writing the bitmap failed not starting resync.\n");
		_drbd_request_state(mdev, NS(conn, C_CONNECTED), CS_VERBOSE);
		return;
	}

	switch (mdev->state.conn) {
	case C_STARTING_SYNC_T:
		_drbd_request_state(mdev, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE);
		break;
	case C_STARTING_SYNC_S:
		drbd_start_resync(mdev, C_SYNC_SOURCE);
		break;
	}
}

/**
 * after_state_ch() - Perform after state change actions that may sleep
 * @mdev:	DRBD device.
 * @os:		old state.
 * @ns:		new state.
 * @flags:	Flags
 */
static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
			   union drbd_state ns, enum chg_state_flags flags)
{
	enum drbd_fencing_p fp;
	enum drbd_req_event what = nothing;
	union drbd_state nsm = (union drbd_state){ .i = -1 };

	if (os.conn != C_CONNECTED && ns.conn == C_CONNECTED) {
		clear_bit(CRASHED_PRIMARY, &mdev->flags);
		if (mdev->p_uuid)
			mdev->p_uuid[UI_FLAGS] &= ~((u64)2);
	}

	fp = FP_DONT_CARE;
	if (get_ldev(mdev)) {
		fp = mdev->ldev->dc.fencing;
		put_ldev(mdev);
	}

	/* Inform userspace about the change... */
	drbd_bcast_state(mdev, ns);

	if (!(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE) &&
	    (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE))
		drbd_khelper(mdev, "pri-on-incon-degr");

	/* Here we have the actions that are performed after a
	   state change. This function might sleep */

	nsm.i = -1;
	if (ns.susp_nod) {
		if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED) {
			if (ns.conn == C_CONNECTED)
				what = resend, nsm.susp_nod = 0;
			else /* ns.conn > C_CONNECTED */
				dev_err(DEV, "Unexpected Resynd going on!\n");
		}

		if (os.disk == D_ATTACHING && ns.disk > D_ATTACHING)
			what = restart_frozen_disk_io, nsm.susp_nod = 0;

	}

	if (ns.susp_fen) {
		/* case1: The outdate peer handler is successful: */
		if (os.pdsk > D_OUTDATED  && ns.pdsk <= D_OUTDATED) {
			tl_clear(mdev);
			if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
				drbd_uuid_new_current(mdev);
				clear_bit(NEW_CUR_UUID, &mdev->flags);
			}
			spin_lock_irq(&mdev->req_lock);
			_drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
			spin_unlock_irq(&mdev->req_lock);
		}
		/* case2: The connection was established again: */
		if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED) {
			clear_bit(NEW_CUR_UUID, &mdev->flags);
			what = resend;
			nsm.susp_fen = 0;
		}
	}

	if (what != nothing) {
		spin_lock_irq(&mdev->req_lock);
		_tl_restart(mdev, what);
		nsm.i &= mdev->state.i;
		_drbd_set_state(mdev, nsm, CS_VERBOSE, NULL);
		spin_unlock_irq(&mdev->req_lock);
	}

	/* Do not change the order of the if above and the two below... */
	if (os.pdsk == D_DISKLESS && ns.pdsk > D_DISKLESS) {      /* attach on the peer */
		drbd_send_uuids(mdev);
		drbd_send_state(mdev);
	}
	if (os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S)
		drbd_queue_bitmap_io(mdev, &drbd_send_bitmap, NULL, "send_bitmap (WFBitMapS)");

	/* Lost contact to peer's copy of the data */
	if ((os.pdsk >= D_INCONSISTENT &&
	     os.pdsk != D_UNKNOWN &&
	     os.pdsk != D_OUTDATED)
	&&  (ns.pdsk < D_INCONSISTENT ||
	     ns.pdsk == D_UNKNOWN ||
	     ns.pdsk == D_OUTDATED)) {
		if (get_ldev(mdev)) {
			if ((ns.role == R_PRIMARY || ns.peer == R_PRIMARY) &&
			    mdev->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
				if (is_susp(mdev->state)) {
					set_bit(NEW_CUR_UUID, &mdev->flags);
				} else {
					drbd_uuid_new_current(mdev);
					drbd_send_uuids(mdev);
				}
			}
			put_ldev(mdev);
		}
	}

	if (ns.pdsk < D_INCONSISTENT && get_ldev(mdev)) {
		if (ns.peer == R_PRIMARY && mdev->ldev->md.uuid[UI_BITMAP] == 0) {
			drbd_uuid_new_current(mdev);
			drbd_send_uuids(mdev);
		}

		/* D_DISKLESS Peer becomes secondary */
		if (os.peer == R_PRIMARY && ns.peer == R_SECONDARY)
			drbd_al_to_on_disk_bm(mdev);
		put_ldev(mdev);
	}

	/* Last part of the attaching process ... */
	if (ns.conn >= C_CONNECTED &&
	    os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) {
		drbd_send_sizes(mdev, 0, 0);  /* to start sync... */
		drbd_send_uuids(mdev);
		drbd_send_state(mdev);
	}

	/* We want to pause/continue resync, tell peer. */
	if (ns.conn >= C_CONNECTED &&
	     ((os.aftr_isp != ns.aftr_isp) ||
	      (os.user_isp != ns.user_isp)))
		drbd_send_state(mdev);

	/* In case one of the isp bits got set, suspend other devices. */
	if ((!os.aftr_isp && !os.peer_isp && !os.user_isp) &&
	    (ns.aftr_isp || ns.peer_isp || ns.user_isp))
		suspend_other_sg(mdev);

	/* Make sure the peer gets informed about eventual state
	   changes (ISP bits) while we were in WFReportParams. */
	if (os.conn == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)
		drbd_send_state(mdev);

	if (os.conn != C_AHEAD && ns.conn == C_AHEAD)
		drbd_send_state(mdev);

	/* We are in the progress to start a full sync... */
	if ((os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
	    (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S))
		drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, &abw_start_sync, "set_n_write from StartingSync");

	/* We are invalidating our self... */
	if (os.conn < C_CONNECTED && ns.conn < C_CONNECTED &&
	    os.disk > D_INCONSISTENT && ns.disk == D_INCONSISTENT)
		drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, NULL, "set_n_write from invalidate");

	/* first half of local IO error, failure to attach,
	 * or administrative detach */
	if (os.disk != D_FAILED && ns.disk == D_FAILED) {
		enum drbd_io_error_p eh;
		int was_io_error;
		/* corresponding get_ldev was in __drbd_set_state, to serialize
		 * our cleanup here with the transition to D_DISKLESS,
		 * so it is safe to dreference ldev here. */
		eh = mdev->ldev->dc.on_io_error;
		was_io_error = test_and_clear_bit(WAS_IO_ERROR, &mdev->flags);

		/* current state still has to be D_FAILED,
		 * there is only one way out: to D_DISKLESS,
		 * and that may only happen after our put_ldev below. */
		if (mdev->state.disk != D_FAILED)
			dev_err(DEV,
				"ASSERT FAILED: disk is %s during detach\n",
				drbd_disk_str(mdev->state.disk));

		if (drbd_send_state(mdev))
			dev_warn(DEV, "Notified peer that I am detaching my disk\n");
		else
			dev_err(DEV, "Sending state for detaching disk failed\n");

		drbd_rs_cancel_all(mdev);

		/* In case we want to get something to stable storage still,
		 * this may be the last chance.
		 * Following put_ldev may transition to D_DISKLESS. */
		drbd_md_sync(mdev);
		put_ldev(mdev);

		if (was_io_error && eh == EP_CALL_HELPER)
			drbd_khelper(mdev, "local-io-error");
	}

        /* second half of local IO error, failure to attach,
         * or administrative detach,
         * after local_cnt references have reached zero again */
        if (os.disk != D_DISKLESS && ns.disk == D_DISKLESS) {
                /* We must still be diskless,
                 * re-attach has to be serialized with this! */
                if (mdev->state.disk != D_DISKLESS)
                        dev_err(DEV,
                                "ASSERT FAILED: disk is %s while going diskless\n",
                                drbd_disk_str(mdev->state.disk));

                mdev->rs_total = 0;
                mdev->rs_failed = 0;
                atomic_set(&mdev->rs_pending_cnt, 0);

		if (drbd_send_state(mdev))
			dev_warn(DEV, "Notified peer that I'm now diskless.\n");
		else
			dev_err(DEV, "Sending state for being diskless failed\n");
		/* corresponding get_ldev in __drbd_set_state
		 * this may finaly trigger drbd_ldev_destroy. */
		put_ldev(mdev);
	}

	/* Disks got bigger while they were detached */
	if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
	    test_and_clear_bit(RESYNC_AFTER_NEG, &mdev->flags)) {
		if (ns.conn == C_CONNECTED)
			resync_after_online_grow(mdev);
	}

	/* A resync finished or aborted, wake paused devices... */
	if ((os.conn > C_CONNECTED && ns.conn <= C_CONNECTED) ||
	    (os.peer_isp && !ns.peer_isp) ||
	    (os.user_isp && !ns.user_isp))
		resume_next_sg(mdev);

	/* sync target done with resync.  Explicitly notify peer, even though
	 * it should (at least for non-empty resyncs) already know itself. */
	if (os.disk < D_UP_TO_DATE && os.conn >= C_SYNC_SOURCE && ns.conn == C_CONNECTED)
		drbd_send_state(mdev);

	/* free tl_hash if we Got thawed and are C_STANDALONE */
	if (ns.conn == C_STANDALONE && !is_susp(ns) && mdev->tl_hash)
		drbd_free_tl_hash(mdev);

	/* Upon network connection, we need to start the receiver */
	if (os.conn == C_STANDALONE && ns.conn == C_UNCONNECTED)
		drbd_thread_start(&mdev->receiver);

	/* Terminate worker thread if we are unconfigured - it will be
	   restarted as needed... */
	if (ns.disk == D_DISKLESS &&
	    ns.conn == C_STANDALONE &&
	    ns.role == R_SECONDARY) {
		if (os.aftr_isp != ns.aftr_isp)
			resume_next_sg(mdev);
		/* set in __drbd_set_state, unless CONFIG_PENDING was set */
		if (test_bit(DEVICE_DYING, &mdev->flags))
			drbd_thread_stop_nowait(&mdev->worker);
	}

	drbd_md_sync(mdev);
}


static int drbd_thread_setup(void *arg)
{
	struct drbd_thread *thi = (struct drbd_thread *) arg;
	struct drbd_conf *mdev = thi->mdev;
	unsigned long flags;
	int retval;

restart:
	retval = thi->function(thi);

	spin_lock_irqsave(&thi->t_lock, flags);

	/* if the receiver has been "Exiting", the last thing it did
	 * was set the conn state to "StandAlone",
	 * if now a re-connect request comes in, conn state goes C_UNCONNECTED,
	 * and receiver thread will be "started".
	 * drbd_thread_start needs to set "Restarting" in that case.
	 * t_state check and assignment needs to be within the same spinlock,
	 * so either thread_start sees Exiting, and can remap to Restarting,
	 * or thread_start see None, and can proceed as normal.
	 */

	if (thi->t_state == Restarting) {
		dev_info(DEV, "Restarting %s\n", current->comm);
		thi->t_state = Running;
		spin_unlock_irqrestore(&thi->t_lock, flags);
		goto restart;
	}

	thi->task = NULL;
	thi->t_state = None;
	smp_mb();
	complete(&thi->stop);
	spin_unlock_irqrestore(&thi->t_lock, flags);

	dev_info(DEV, "Terminating %s\n", current->comm);

	/* Release mod reference taken when thread was started */
	module_put(THIS_MODULE);
	return retval;
}

static void drbd_thread_init(struct drbd_conf *mdev, struct drbd_thread *thi,
		      int (*func) (struct drbd_thread *))
{
	spin_lock_init(&thi->t_lock);
	thi->task    = NULL;
	thi->t_state = None;
	thi->function = func;
	thi->mdev = mdev;
}

int drbd_thread_start(struct drbd_thread *thi)
{
	struct drbd_conf *mdev = thi->mdev;
	struct task_struct *nt;
	unsigned long flags;

	const char *me =
		thi == &mdev->receiver ? "receiver" :
		thi == &mdev->asender  ? "asender"  :
		thi == &mdev->worker   ? "worker"   : "NONSENSE";

	/* is used from state engine doing drbd_thread_stop_nowait,
	 * while holding the req lock irqsave */
	spin_lock_irqsave(&thi->t_lock, flags);

	switch (thi->t_state) {
	case None:
		dev_info(DEV, "Starting %s thread (from %s [%d])\n",
				me, current->comm, current->pid);

		/* Get ref on module for thread - this is released when thread exits */
		if (!try_module_get(THIS_MODULE)) {
			dev_err(DEV, "Failed to get module reference in drbd_thread_start\n");
			spin_unlock_irqrestore(&thi->t_lock, flags);
			return false;
		}

		init_completion(&thi->stop);
		D_ASSERT(thi->task == NULL);
		thi->reset_cpu_mask = 1;
		thi->t_state = Running;
		spin_unlock_irqrestore(&thi->t_lock, flags);
		flush_signals(current); /* otherw. may get -ERESTARTNOINTR */

		nt = kthread_create(drbd_thread_setup, (void *) thi,
				    "drbd%d_%s", mdev_to_minor(mdev), me);

		if (IS_ERR(nt)) {
			dev_err(DEV, "Couldn't start thread\n");

			module_put(THIS_MODULE);
			return false;
		}
		spin_lock_irqsave(&thi->t_lock, flags);
		thi->task = nt;
		thi->t_state = Running;
		spin_unlock_irqrestore(&thi->t_lock, flags);
		wake_up_process(nt);
		break;
	case Exiting:
		thi->t_state = Restarting;
		dev_info(DEV, "Restarting %s thread (from %s [%d])\n",
				me, current->comm, current->pid);
		/* fall through */
	case Running:
	case Restarting:
	default:
		spin_unlock_irqrestore(&thi->t_lock, flags);
		break;
	}

	return true;
}


void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait)
{
	unsigned long flags;

	enum drbd_thread_state ns = restart ? Restarting : Exiting;

	/* may be called from state engine, holding the req lock irqsave */
	spin_lock_irqsave(&thi->t_lock, flags);

	if (thi->t_state == None) {
		spin_unlock_irqrestore(&thi->t_lock, flags);
		if (restart)
			drbd_thread_start(thi);
		return;
	}

	if (thi->t_state != ns) {
		if (thi->task == NULL) {
			spin_unlock_irqrestore(&thi->t_lock, flags);
			return;
		}

		thi->t_state = ns;
		smp_mb();
		init_completion(&thi->stop);
		if (thi->task != current)
			force_sig(DRBD_SIGKILL, thi->task);

	}

	spin_unlock_irqrestore(&thi->t_lock, flags);

	if (wait)
		wait_for_completion(&thi->stop);
}

#ifdef CONFIG_SMP
/**
 * drbd_calc_cpu_mask() - Generate CPU masks, spread over all CPUs
 * @mdev:	DRBD device.
 *
 * Forces all threads of a device onto the same CPU. This is beneficial for
 * DRBD's performance. May be overwritten by user's configuration.
 */
void drbd_calc_cpu_mask(struct drbd_conf *mdev)
{
	int ord, cpu;

	/* user override. */
	if (cpumask_weight(mdev->cpu_mask))
		return;

	ord = mdev_to_minor(mdev) % cpumask_weight(cpu_online_mask);
	for_each_online_cpu(cpu) {
		if (ord-- == 0) {
			cpumask_set_cpu(cpu, mdev->cpu_mask);
			return;
		}
	}
	/* should not be reached */
	cpumask_setall(mdev->cpu_mask);
}

/**
 * drbd_thread_current_set_cpu() - modifies the cpu mask of the _current_ thread
 * @mdev:	DRBD device.
 *
 * call in the "main loop" of _all_ threads, no need for any mutex, current won't die
 * prematurely.
 */
void drbd_thread_current_set_cpu(struct drbd_conf *mdev)
{
	struct task_struct *p = current;
	struct drbd_thread *thi =
		p == mdev->asender.task  ? &mdev->asender  :
		p == mdev->receiver.task ? &mdev->receiver :
		p == mdev->worker.task   ? &mdev->worker   :
		NULL;
	ERR_IF(thi == NULL)
		return;
	if (!thi->reset_cpu_mask)
		return;
	thi->reset_cpu_mask = 0;
	set_cpus_allowed_ptr(p, mdev->cpu_mask);
}
#endif

/* the appropriate socket mutex must be held already */
int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
			  enum drbd_packets cmd, struct p_header80 *h,
			  size_t size, unsigned msg_flags)
{
	int sent, ok;

	ERR_IF(!h) return false;
	ERR_IF(!size) return false;

	h->magic   = BE_DRBD_MAGIC;
	h->command = cpu_to_be16(cmd);
	h->length  = cpu_to_be16(size-sizeof(struct p_header80));

	sent = drbd_send(mdev, sock, h, size, msg_flags);

	ok = (sent == size);
	if (!ok)
		dev_err(DEV, "short sent %s size=%d sent=%d\n",
		    cmdname(cmd), (int)size, sent);
	return ok;
}

/* don't pass the socket. we may only look at it
 * when we hold the appropriate socket mutex.
 */
int drbd_send_cmd(struct drbd_conf *mdev, int use_data_socket,
		  enum drbd_packets cmd, struct p_header80 *h, size_t size)
{
	int ok = 0;
	struct socket *sock;

	if (use_data_socket) {
		mutex_lock(&mdev->data.mutex);
		sock = mdev->data.socket;
	} else {
		mutex_lock(&mdev->meta.mutex);
		sock = mdev->meta.socket;
	}

	/* drbd_disconnect() could have called drbd_free_sock()
	 * while we were waiting in down()... */
	if (likely(sock != NULL))
		ok = _drbd_send_cmd(mdev, sock, cmd, h, size, 0);

	if (use_data_socket)
		mutex_unlock(&mdev->data.mutex);
	else
		mutex_unlock(&mdev->meta.mutex);
	return ok;
}

int drbd_send_cmd2(struct drbd_conf *mdev, enum drbd_packets cmd, char *data,
		   size_t size)
{
	struct p_header80 h;
	int ok;

	h.magic   = BE_DRBD_MAGIC;
	h.command = cpu_to_be16(cmd);
	h.length  = cpu_to_be16(size);

	if (!drbd_get_data_sock(mdev))
		return 0;

	ok = (sizeof(h) ==
		drbd_send(mdev, mdev->data.socket, &h, sizeof(h), 0));
	ok = ok && (size ==
		drbd_send(mdev, mdev->data.socket, data, size, 0));

	drbd_put_data_sock(mdev);

	return ok;
}

int drbd_send_sync_param(struct drbd_conf *mdev, struct syncer_conf *sc)
{
	struct p_rs_param_95 *p;
	struct socket *sock;
	int size, rv;
	const int apv = mdev->agreed_pro_version;

	size = apv <= 87 ? sizeof(struct p_rs_param)
		: apv == 88 ? sizeof(struct p_rs_param)
			+ strlen(mdev->sync_conf.verify_alg) + 1
		: apv <= 94 ? sizeof(struct p_rs_param_89)
		: /* apv >= 95 */ sizeof(struct p_rs_param_95);

	/* used from admin command context and receiver/worker context.
	 * to avoid kmalloc, grab the socket right here,
	 * then use the pre-allocated sbuf there */
	mutex_lock(&mdev->data.mutex);
	sock = mdev->data.socket;

	if (likely(sock != NULL)) {
		enum drbd_packets cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;

		p = &mdev->data.sbuf.rs_param_95;

		/* initialize verify_alg and csums_alg */
		memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);

		p->rate = cpu_to_be32(sc->rate);
		p->c_plan_ahead = cpu_to_be32(sc->c_plan_ahead);
		p->c_delay_target = cpu_to_be32(sc->c_delay_target);
		p->c_fill_target = cpu_to_be32(sc->c_fill_target);
		p->c_max_rate = cpu_to_be32(sc->c_max_rate);

		if (apv >= 88)
			strcpy(p->verify_alg, mdev->sync_conf.verify_alg);
		if (apv >= 89)
			strcpy(p->csums_alg, mdev->sync_conf.csums_alg);

		rv = _drbd_send_cmd(mdev, sock, cmd, &p->head, size, 0);
	} else
		rv = 0; /* not ok */

	mutex_unlock(&mdev->data.mutex);

	return rv;
}

int drbd_send_protocol(struct drbd_conf *mdev)
{
	struct p_protocol *p;
	int size, cf, rv;

	size = sizeof(struct p_protocol);

	if (mdev->agreed_pro_version >= 87)
		size += strlen(mdev->net_conf->integrity_alg) + 1;

	/* we must not recurse into our own queue,
	 * as that is blocked during handshake */
	p = kmalloc(size, GFP_NOIO);
	if (p == NULL)
		return 0;

	p->protocol      = cpu_to_be32(mdev->net_conf->wire_protocol);
	p->after_sb_0p   = cpu_to_be32(mdev->net_conf->after_sb_0p);
	p->after_sb_1p   = cpu_to_be32(mdev->net_conf->after_sb_1p);
	p->after_sb_2p   = cpu_to_be32(mdev->net_conf->after_sb_2p);
	p->two_primaries = cpu_to_be32(mdev->net_conf->two_primaries);

	cf = 0;
	if (mdev->net_conf->want_lose)
		cf |= CF_WANT_LOSE;
	if (mdev->net_conf->dry_run) {
		if (mdev->agreed_pro_version >= 92)
			cf |= CF_DRY_RUN;
		else {
			dev_err(DEV, "--dry-run is not supported by peer");
			kfree(p);
			return 0;
		}
	}
	p->conn_flags    = cpu_to_be32(cf);

	if (mdev->agreed_pro_version >= 87)
		strcpy(p->integrity_alg, mdev->net_conf->integrity_alg);

	rv = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_PROTOCOL,
			   (struct p_header80 *)p, size);
	kfree(p);
	return rv;
}

int _drbd_send_uuids(struct drbd_conf *mdev, u64 uuid_flags)
{
	struct p_uuids p;
	int i;

	if (!get_ldev_if_state(mdev, D_NEGOTIATING))
		return 1;

	for (i = UI_CURRENT; i < UI_SIZE; i++)
		p.uuid[i] = mdev->ldev ? cpu_to_be64(mdev->ldev->md.uuid[i]) : 0;

	mdev->comm_bm_set = drbd_bm_total_weight(mdev);
	p.uuid[UI_SIZE] = cpu_to_be64(mdev->comm_bm_set);
	uuid_flags |= mdev->net_conf->want_lose ? 1 : 0;
	uuid_flags |= test_bit(CRASHED_PRIMARY, &mdev->flags) ? 2 : 0;
	uuid_flags |= mdev->new_state_tmp.disk == D_INCONSISTENT ? 4 : 0;
	p.uuid[UI_FLAGS] = cpu_to_be64(uuid_flags);

	put_ldev(mdev);

	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_UUIDS,
			     (struct p_header80 *)&p, sizeof(p));
}

int drbd_send_uuids(struct drbd_conf *mdev)
{
	return _drbd_send_uuids(mdev, 0);
}

int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev)
{
	return _drbd_send_uuids(mdev, 8);
}


int drbd_send_sync_uuid(struct drbd_conf *mdev, u64 val)
{
	struct p_rs_uuid p;

	p.uuid = cpu_to_be64(val);

	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SYNC_UUID,
			     (struct p_header80 *)&p, sizeof(p));
}

int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags)
{
	struct p_sizes p;
	sector_t d_size, u_size;
	int q_order_type;
	int ok;

	if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
		D_ASSERT(mdev->ldev->backing_bdev);
		d_size = drbd_get_max_capacity(mdev->ldev);
		u_size = mdev->ldev->dc.disk_size;
		q_order_type = drbd_queue_order_type(mdev);
		put_ldev(mdev);
	} else {
		d_size = 0;
		u_size = 0;
		q_order_type = QUEUE_ORDERED_NONE;
	}

	p.d_size = cpu_to_be64(d_size);
	p.u_size = cpu_to_be64(u_size);
	p.c_size = cpu_to_be64(trigger_reply ? 0 : drbd_get_capacity(mdev->this_bdev));
	p.max_bio_size = cpu_to_be32(queue_max_hw_sectors(mdev->rq_queue) << 9);
	p.queue_order_type = cpu_to_be16(q_order_type);
	p.dds_flags = cpu_to_be16(flags);

	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SIZES,
			   (struct p_header80 *)&p, sizeof(p));
	return ok;
}

/**
 * drbd_send_state() - Sends the drbd state to the peer
 * @mdev:	DRBD device.
 */
int drbd_send_state(struct drbd_conf *mdev)
{
	struct socket *sock;
	struct p_state p;
	int ok = 0;

	/* Grab state lock so we wont send state if we're in the middle
	 * of a cluster wide state change on another thread */
	drbd_state_lock(mdev);

	mutex_lock(&mdev->data.mutex);

	p.state = cpu_to_be32(mdev->state.i); /* Within the send mutex */
	sock = mdev->data.socket;

	if (likely(sock != NULL)) {
		ok = _drbd_send_cmd(mdev, sock, P_STATE,
				    (struct p_header80 *)&p, sizeof(p), 0);
	}

	mutex_unlock(&mdev->data.mutex);

	drbd_state_unlock(mdev);
	return ok;
}

int drbd_send_state_req(struct drbd_conf *mdev,
	union drbd_state mask, union drbd_state val)
{
	struct p_req_state p;

	p.mask    = cpu_to_be32(mask.i);
	p.val     = cpu_to_be32(val.i);

	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_STATE_CHG_REQ,
			     (struct p_header80 *)&p, sizeof(p));
}

int drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode)
{
	struct p_req_state_reply p;

	p.retcode    = cpu_to_be32(retcode);

	return drbd_send_cmd(mdev, USE_META_SOCKET, P_STATE_CHG_REPLY,
			     (struct p_header80 *)&p, sizeof(p));
}

int fill_bitmap_rle_bits(struct drbd_conf *mdev,
	struct p_compressed_bm *p,
	struct bm_xfer_ctx *c)
{
	struct bitstream bs;
	unsigned long plain_bits;
	unsigned long tmp;
	unsigned long rl;
	unsigned len;
	unsigned toggle;
	int bits;

	/* may we use this feature? */
	if ((mdev->sync_conf.use_rle == 0) ||
		(mdev->agreed_pro_version < 90))
			return 0;

	if (c->bit_offset >= c->bm_bits)
		return 0; /* nothing to do. */

	/* use at most thus many bytes */
	bitstream_init(&bs, p->code, BM_PACKET_VLI_BYTES_MAX, 0);
	memset(p->code, 0, BM_PACKET_VLI_BYTES_MAX);
	/* plain bits covered in this code string */
	plain_bits = 0;

	/* p->encoding & 0x80 stores whether the first run length is set.
	 * bit offset is implicit.
	 * start with toggle == 2 to be able to tell the first iteration */
	toggle = 2;

	/* see how much plain bits we can stuff into one packet
	 * using RLE and VLI. */
	do {
		tmp = (toggle == 0) ? _drbd_bm_find_next_zero(mdev, c->bit_offset)
				    : _drbd_bm_find_next(mdev, c->bit_offset);
		if (tmp == -1UL)
			tmp = c->bm_bits;
		rl = tmp - c->bit_offset;

		if (toggle == 2) { /* first iteration */
			if (rl == 0) {
				/* the first checked bit was set,
				 * store start value, */
				DCBP_set_start(p, 1);
				/* but skip encoding of zero run length */
				toggle = !toggle;
				continue;
			}
			DCBP_set_start(p, 0);
		}

		/* paranoia: catch zero runlength.
		 * can only happen if bitmap is modified while we scan it. */
		if (rl == 0) {
			dev_err(DEV, "unexpected zero runlength while encoding bitmap "
			    "t:%u bo:%lu\n", toggle, c->bit_offset);
			return -1;
		}

		bits = vli_encode_bits(&bs, rl);
		if (bits == -ENOBUFS) /* buffer full */
			break;
		if (bits <= 0) {
			dev_err(DEV, "error while encoding bitmap: %d\n", bits);
			return 0;
		}

		toggle = !toggle;
		plain_bits += rl;
		c->bit_offset = tmp;
	} while (c->bit_offset < c->bm_bits);

	len = bs.cur.b - p->code + !!bs.cur.bit;

	if (plain_bits < (len << 3)) {
		/* incompressible with this method.
		 * we need to rewind both word and bit position. */
		c->bit_offset -= plain_bits;
		bm_xfer_ctx_bit_to_word_offset(c);
		c->bit_offset = c->word_offset * BITS_PER_LONG;
		return 0;
	}

	/* RLE + VLI was able to compress it just fine.
	 * update c->word_offset. */
	bm_xfer_ctx_bit_to_word_offset(c);

	/* store pad_bits */
	DCBP_set_pad_bits(p, (8 - bs.cur.bit) & 0x7);

	return len;
}

enum { OK, FAILED, DONE }
send_bitmap_rle_or_plain(struct drbd_conf *mdev,
	struct p_header80 *h, struct bm_xfer_ctx *c)
{
	struct p_compressed_bm *p = (void*)h;
	unsigned long num_words;
	int len;
	int ok;

	len = fill_bitmap_rle_bits(mdev, p, c);

	if (len < 0)
		return FAILED;

	if (len) {
		DCBP_set_code(p, RLE_VLI_Bits);
		ok = _drbd_send_cmd(mdev, mdev->data.socket, P_COMPRESSED_BITMAP, h,
			sizeof(*p) + len, 0);

		c->packets[0]++;
		c->bytes[0] += sizeof(*p) + len;

		if (c->bit_offset >= c->bm_bits)
			len = 0; /* DONE */
	} else {
		/* was not compressible.
		 * send a buffer full of plain text bits instead. */
		num_words = min_t(size_t, BM_PACKET_WORDS, c->bm_words - c->word_offset);
		len = num_words * sizeof(long);
		if (len)
			drbd_bm_get_lel(mdev, c->word_offset, num_words, (unsigned long*)h->payload);
		ok = _drbd_send_cmd(mdev, mdev->data.socket, P_BITMAP,
				   h, sizeof(struct p_header80) + len, 0);
		c->word_offset += num_words;
		c->bit_offset = c->word_offset * BITS_PER_LONG;

		c->packets[1]++;
		c->bytes[1] += sizeof(struct p_header80) + len;

		if (c->bit_offset > c->bm_bits)
			c->bit_offset = c->bm_bits;
	}
	ok = ok ? ((len == 0) ? DONE : OK) : FAILED;

	if (ok == DONE)
		INFO_bm_xfer_stats(mdev, "send", c);
	return ok;
}

/* See the comment at receive_bitmap() */
int _drbd_send_bitmap(struct drbd_conf *mdev)
{
	struct bm_xfer_ctx c;
	struct p_header80 *p;
	int ret;

	ERR_IF(!mdev->bitmap) return false;

	/* maybe we should use some per thread scratch page,
	 * and allocate that during initial device creation? */
	p = (struct p_header80 *) __get_free_page(GFP_NOIO);
	if (!p) {
		dev_err(DEV, "failed to allocate one page buffer in %s\n", __func__);
		return false;
	}

	if (get_ldev(mdev)) {
		if (drbd_md_test_flag(mdev->ldev, MDF_FULL_SYNC)) {
			dev_info(DEV, "Writing the whole bitmap, MDF_FullSync was set.\n");
			drbd_bm_set_all(mdev);
			if (drbd_bm_write(mdev)) {
				/* write_bm did fail! Leave full sync flag set in Meta P_DATA
				 * but otherwise process as per normal - need to tell other
				 * side that a full resync is required! */
				dev_err(DEV, "Failed to write bitmap to disk!\n");
			} else {
				drbd_md_clear_flag(mdev, MDF_FULL_SYNC);
				drbd_md_sync(mdev);
			}
		}
		put_ldev(mdev);
	}

	c = (struct bm_xfer_ctx) {
		.bm_bits = drbd_bm_bits(mdev),
		.bm_words = drbd_bm_words(mdev),
	};

	do {
		ret = send_bitmap_rle_or_plain(mdev, p, &c);
	} while (ret == OK);

	free_page((unsigned long) p);
	return (ret == DONE);
}

int drbd_send_bitmap(struct drbd_conf *mdev)
{
	int err;

	if (!drbd_get_data_sock(mdev))
		return -1;
	err = !_drbd_send_bitmap(mdev);
	drbd_put_data_sock(mdev);
	return err;
}

int drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr, u32 set_size)
{
	int ok;
	struct p_barrier_ack p;

	p.barrier  = barrier_nr;
	p.set_size = cpu_to_be32(set_size);

	if (mdev->state.conn < C_CONNECTED)
		return false;
	ok = drbd_send_cmd(mdev, USE_META_SOCKET, P_BARRIER_ACK,
			(struct p_header80 *)&p, sizeof(p));
	return ok;
}

/**
 * _drbd_send_ack() - Sends an ack packet
 * @mdev:	DRBD device.
 * @cmd:	Packet command code.
 * @sector:	sector, needs to be in big endian byte order
 * @blksize:	size in byte, needs to be in big endian byte order
 * @block_id:	Id, big endian byte order
 */
static int _drbd_send_ack(struct drbd_conf *mdev, enum drbd_packets cmd,
			  u64 sector,
			  u32 blksize,
			  u64 block_id)
{
	int ok;
	struct p_block_ack p;

	p.sector   = sector;
	p.block_id = block_id;
	p.blksize  = blksize;
	p.seq_num  = cpu_to_be32(atomic_add_return(1, &mdev->packet_seq));

	if (!mdev->meta.socket || mdev->state.conn < C_CONNECTED)
		return false;
	ok = drbd_send_cmd(mdev, USE_META_SOCKET, cmd,
				(struct p_header80 *)&p, sizeof(p));
	return ok;
}

/* dp->sector and dp->block_id already/still in network byte order,
 * data_size is payload size according to dp->head,
 * and may need to be corrected for digest size. */
int drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packets cmd,
		     struct p_data *dp, int data_size)
{
	data_size -= (mdev->agreed_pro_version >= 87 && mdev->integrity_r_tfm) ?
		crypto_hash_digestsize(mdev->integrity_r_tfm) : 0;
	return _drbd_send_ack(mdev, cmd, dp->sector, cpu_to_be32(data_size),
			      dp->block_id);
}

int drbd_send_ack_rp(struct drbd_conf *mdev, enum drbd_packets cmd,
		     struct p_block_req *rp)
{
	return _drbd_send_ack(mdev, cmd, rp->sector, rp->blksize, rp->block_id);
}

/**
 * drbd_send_ack() - Sends an ack packet
 * @mdev:	DRBD device.
 * @cmd:	Packet command code.
 * @e:		Epoch entry.
 */
int drbd_send_ack(struct drbd_conf *mdev,
	enum drbd_packets cmd, struct drbd_epoch_entry *e)
{
	return _drbd_send_ack(mdev, cmd,
			      cpu_to_be64(e->sector),
			      cpu_to_be32(e->size),
			      e->block_id);
}

/* This function misuses the block_id field to signal if the blocks
 * are is sync or not. */
int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packets cmd,
		     sector_t sector, int blksize, u64 block_id)
{
	return _drbd_send_ack(mdev, cmd,
			      cpu_to_be64(sector),
			      cpu_to_be32(blksize),
			      cpu_to_be64(block_id));
}

int drbd_send_drequest(struct drbd_conf *mdev, int cmd,
		       sector_t sector, int size, u64 block_id)
{
	int ok;
	struct p_block_req p;

	p.sector   = cpu_to_be64(sector);
	p.block_id = block_id;
	p.blksize  = cpu_to_be32(size);

	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, cmd,
				(struct p_header80 *)&p, sizeof(p));
	return ok;
}

int drbd_send_drequest_csum(struct drbd_conf *mdev,
			    sector_t sector, int size,
			    void *digest, int digest_size,
			    enum drbd_packets cmd)
{
	int ok;
	struct p_block_req p;

	p.sector   = cpu_to_be64(sector);
	p.block_id = BE_DRBD_MAGIC + 0xbeef;
	p.blksize  = cpu_to_be32(size);

	p.head.magic   = BE_DRBD_MAGIC;
	p.head.command = cpu_to_be16(cmd);
	p.head.length  = cpu_to_be16(sizeof(p) - sizeof(struct p_header80) + digest_size);

	mutex_lock(&mdev->data.mutex);

	ok = (sizeof(p) == drbd_send(mdev, mdev->data.socket, &p, sizeof(p), 0));
	ok = ok && (digest_size == drbd_send(mdev, mdev->data.socket, digest, digest_size, 0));

	mutex_unlock(&mdev->data.mutex);

	return ok;
}

int drbd_send_ov_request(struct drbd_conf *mdev, sector_t sector, int size)
{
	int ok;
	struct p_block_req p;

	p.sector   = cpu_to_be64(sector);
	p.block_id = BE_DRBD_MAGIC + 0xbabe;
	p.blksize  = cpu_to_be32(size);

	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_OV_REQUEST,
			   (struct p_header80 *)&p, sizeof(p));
	return ok;
}

/* called on sndtimeo
 * returns false if we should retry,
 * true if we think connection is dead
 */
static int we_should_drop_the_connection(struct drbd_conf *mdev, struct socket *sock)
{
	int drop_it;
	/* long elapsed = (long)(jiffies - mdev->last_received); */

	drop_it =   mdev->meta.socket == sock
		|| !mdev->asender.task
		|| get_t_state(&mdev->asender) != Running
		|| mdev->state.conn < C_CONNECTED;

	if (drop_it)
		return true;

	drop_it = !--mdev->ko_count;
	if (!drop_it) {
		dev_err(DEV, "[%s/%d] sock_sendmsg time expired, ko = %u\n",
		       current->comm, current->pid, mdev->ko_count);
		request_ping(mdev);
	}

	return drop_it; /* && (mdev->state == R_PRIMARY) */;
}

/* The idea of sendpage seems to be to put some kind of reference
 * to the page into the skb, and to hand it over to the NIC. In
 * this process get_page() gets called.
 *
 * As soon as the page was really sent over the network put_page()
 * gets called by some part of the network layer. [ NIC driver? ]
 *
 * [ get_page() / put_page() increment/decrement the count. If count
 *   reaches 0 the page will be freed. ]
 *
 * This works nicely with pages from FSs.
 * But this means that in protocol A we might signal IO completion too early!
 *
 * In order not to corrupt data during a resync we must make sure
 * that we do not reuse our own buffer pages (EEs) to early, therefore
 * we have the net_ee list.
 *
 * XFS seems to have problems, still, it submits pages with page_count == 0!
 * As a workaround, we disable sendpage on pages
 * with page_count == 0 or PageSlab.
 */
static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,
		   int offset, size_t size, unsigned msg_flags)
{
	int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, msg_flags);
	kunmap(page);
	if (sent == size)
		mdev->send_cnt += size>>9;
	return sent == size;
}

static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
		    int offset, size_t size, unsigned msg_flags)
{
	mm_segment_t oldfs = get_fs();
	int sent, ok;
	int len = size;

	/* e.g. XFS meta- & log-data is in slab pages, which have a
	 * page_count of 0 and/or have PageSlab() set.
	 * we cannot use send_page for those, as that does get_page();
	 * put_page(); and would cause either a VM_BUG directly, or
	 * __page_cache_release a page that would actually still be referenced
	 * by someone, leading to some obscure delayed Oops somewhere else. */
	if (disable_sendpage || (page_count(page) < 1) || PageSlab(page))
		return _drbd_no_send_page(mdev, page, offset, size, msg_flags);

	msg_flags |= MSG_NOSIGNAL;
	drbd_update_congested(mdev);
	set_fs(KERNEL_DS);
	do {
		sent = mdev->data.socket->ops->sendpage(mdev->data.socket, page,
							offset, len,
							msg_flags);
		if (sent == -EAGAIN) {
			if (we_should_drop_the_connection(mdev,
							  mdev->data.socket))
				break;
			else
				continue;
		}
		if (sent <= 0) {
			dev_warn(DEV, "%s: size=%d len=%d sent=%d\n",
			     __func__, (int)size, len, sent);
			break;
		}
		len    -= sent;
		offset += sent;
	} while (len > 0 /* THINK && mdev->cstate >= C_CONNECTED*/);
	set_fs(oldfs);
	clear_bit(NET_CONGESTED, &mdev->flags);

	ok = (len == 0);
	if (likely(ok))
		mdev->send_cnt += size>>9;
	return ok;
}

static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
{
	struct bio_vec *bvec;
	int i;
	/* hint all but last page with MSG_MORE */
	__bio_for_each_segment(bvec, bio, i, 0) {
		if (!_drbd_no_send_page(mdev, bvec->bv_page,
				     bvec->bv_offset, bvec->bv_len,
				     i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
			return 0;
	}
	return 1;
}

static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
{
	struct bio_vec *bvec;
	int i;
	/* hint all but last page with MSG_MORE */
	__bio_for_each_segment(bvec, bio, i, 0) {
		if (!_drbd_send_page(mdev, bvec->bv_page,
				     bvec->bv_offset, bvec->bv_len,
				     i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
			return 0;
	}
	return 1;
}

static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
{
	struct page *page = e->pages;
	unsigned len = e->size;
	/* hint all but last page with MSG_MORE */
	page_chain_for_each(page) {
		unsigned l = min_t(unsigned, len, PAGE_SIZE);
		if (!_drbd_send_page(mdev, page, 0, l,
				page_chain_next(page) ? MSG_MORE : 0))
			return 0;
		len -= l;
	}
	return 1;
}

static u32 bio_flags_to_wire(struct drbd_conf *mdev, unsigned long bi_rw)
{
	if (mdev->agreed_pro_version >= 95)
		return  (bi_rw & REQ_SYNC ? DP_RW_SYNC : 0) |
			(bi_rw & REQ_FUA ? DP_FUA : 0) |
			(bi_rw & REQ_FLUSH ? DP_FLUSH : 0) |
			(bi_rw & REQ_DISCARD ? DP_DISCARD : 0);
	else
		return bi_rw & REQ_SYNC ? DP_RW_SYNC : 0;
}

/* Used to send write requests
 * R_PRIMARY -> Peer	(P_DATA)
 */
int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
{
	int ok = 1;
	struct p_data p;
	unsigned int dp_flags = 0;
	void *dgb;
	int dgs;

	if (!drbd_get_data_sock(mdev))
		return 0;

	dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
		crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;

	if (req->size <= DRBD_MAX_SIZE_H80_PACKET) {
		p.head.h80.magic   = BE_DRBD_MAGIC;
		p.head.h80.command = cpu_to_be16(P_DATA);
		p.head.h80.length  =
			cpu_to_be16(sizeof(p) - sizeof(union p_header) + dgs + req->size);
	} else {
		p.head.h95.magic   = BE_DRBD_MAGIC_BIG;
		p.head.h95.command = cpu_to_be16(P_DATA);
		p.head.h95.length  =
			cpu_to_be32(sizeof(p) - sizeof(union p_header) + dgs + req->size);
	}

	p.sector   = cpu_to_be64(req->sector);
	p.block_id = (unsigned long)req;
	p.seq_num  = cpu_to_be32(req->seq_num =
				 atomic_add_return(1, &mdev->packet_seq));

	dp_flags = bio_flags_to_wire(mdev, req->master_bio->bi_rw);

	if (mdev->state.conn >= C_SYNC_SOURCE &&
	    mdev->state.conn <= C_PAUSED_SYNC_T)
		dp_flags |= DP_MAY_SET_IN_SYNC;

	p.dp_flags = cpu_to_be32(dp_flags);
	set_bit(UNPLUG_REMOTE, &mdev->flags);
	ok = (sizeof(p) ==
		drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0));
	if (ok && dgs) {
		dgb = mdev->int_dig_out;
		drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
		ok = dgs == drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
	}
	if (ok) {
		/* For protocol A, we have to memcpy the payload into
		 * socket buffers, as we may complete right away
		 * as soon as we handed it over to tcp, at which point the data
		 * pages may become invalid.
		 *
		 * For data-integrity enabled, we copy it as well, so we can be
		 * sure that even if the bio pages may still be modified, it
		 * won't change the data on the wire, thus if the digest checks
		 * out ok after sending on this side, but does not fit on the
		 * receiving side, we sure have detected corruption elsewhere.
		 */
		if (mdev->net_conf->wire_protocol == DRBD_PROT_A || dgs)
			ok = _drbd_send_bio(mdev, req->master_bio);
		else
			ok = _drbd_send_zc_bio(mdev, req->master_bio);

		/* double check digest, sometimes buffers have been modified in flight. */
		if (dgs > 0 && dgs <= 64) {
			/* 64 byte, 512 bit, is the larges digest size
			 * currently supported in kernel crypto. */
			unsigned char digest[64];
			drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, digest);
			if (memcmp(mdev->int_dig_out, digest, dgs)) {
				dev_warn(DEV,
					"Digest mismatch, buffer modified by upper layers during write: %llus +%u\n",
					(unsigned long long)req->sector, req->size);
			}
		} /* else if (dgs > 64) {
		     ... Be noisy about digest too large ...
		} */
	}

	drbd_put_data_sock(mdev);

	return ok;
}

/* answer packet, used to send data back for read requests:
 *  Peer       -> (diskless) R_PRIMARY   (P_DATA_REPLY)
 *  C_SYNC_SOURCE -> C_SYNC_TARGET         (P_RS_DATA_REPLY)
 */
int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd,
		    struct drbd_epoch_entry *e)
{
	int ok;
	struct p_data p;
	void *dgb;
	int dgs;

	dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
		crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;

	if (e->size <= DRBD_MAX_SIZE_H80_PACKET) {
		p.head.h80.magic   = BE_DRBD_MAGIC;
		p.head.h80.command = cpu_to_be16(cmd);
		p.head.h80.length  =
			cpu_to_be16(sizeof(p) - sizeof(struct p_header80) + dgs + e->size);
	} else {
		p.head.h95.magic   = BE_DRBD_MAGIC_BIG;
		p.head.h95.command = cpu_to_be16(cmd);
		p.head.h95.length  =
			cpu_to_be32(sizeof(p) - sizeof(struct p_header80) + dgs + e->size);
	}

	p.sector   = cpu_to_be64(e->sector);
	p.block_id = e->block_id;
	/* p.seq_num  = 0;    No sequence numbers here.. */

	/* Only called by our kernel thread.
	 * This one may be interrupted by DRBD_SIG and/or DRBD_SIGKILL
	 * in response to admin command or module unload.
	 */
	if (!drbd_get_data_sock(mdev))
		return 0;

	ok = sizeof(p) == drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0);
	if (ok && dgs) {
		dgb = mdev->int_dig_out;
		drbd_csum_ee(mdev, mdev->integrity_w_tfm, e, dgb);
		ok = dgs == drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
	}
	if (ok)
		ok = _drbd_send_zc_ee(mdev, e);

	drbd_put_data_sock(mdev);

	return ok;
}

int drbd_send_oos(struct drbd_conf *mdev, struct drbd_request *req)
{
	struct p_block_desc p;

	p.sector  = cpu_to_be64(req->sector);
	p.blksize = cpu_to_be32(req->size);

	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_OUT_OF_SYNC, &p.head, sizeof(p));
}

/*
  drbd_send distinguishes two cases:

  Packets sent via the data socket "sock"
  and packets sent via the meta data socket "msock"

		    sock                      msock
  -----------------+-------------------------+------------------------------
  timeout           conf.timeout / 2          conf.timeout / 2
  timeout action    send a ping via msock     Abort communication
					      and close all sockets
*/

/*
 * you must have down()ed the appropriate [m]sock_mutex elsewhere!
 */
int drbd_send(struct drbd_conf *mdev, struct socket *sock,
	      void *buf, size_t size, unsigned msg_flags)
{
	struct kvec iov;
	struct msghdr msg;
	int rv, sent = 0;

	if (!sock)
		return -1000;

	/* THINK  if (signal_pending) return ... ? */

	iov.iov_base = buf;
	iov.iov_len  = size;

	msg.msg_name       = NULL;
	msg.msg_namelen    = 0;
	msg.msg_control    = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags      = msg_flags | MSG_NOSIGNAL;

	if (sock == mdev->data.socket) {
		mdev->ko_count = mdev->net_conf->ko_count;
		drbd_update_congested(mdev);
	}
	do {
		/* STRANGE
		 * tcp_sendmsg does _not_ use its size parameter at all ?
		 *
		 * -EAGAIN on timeout, -EINTR on signal.
		 */
/* THINK
 * do we need to block DRBD_SIG if sock == &meta.socket ??
 * otherwise wake_asender() might interrupt some send_*Ack !
 */
		rv = kernel_sendmsg(sock, &msg, &iov, 1, size);
		if (rv == -EAGAIN) {
			if (we_should_drop_the_connection(mdev, sock))
				break;
			else
				continue;
		}
		D_ASSERT(rv != 0);
		if (rv == -EINTR) {
			flush_signals(current);
			rv = 0;
		}
		if (rv < 0)
			break;
		sent += rv;
		iov.iov_base += rv;
		iov.iov_len  -= rv;
	} while (sent < size);

	if (sock == mdev->data.socket)
		clear_bit(NET_CONGESTED, &mdev->flags);

	if (rv <= 0) {
		if (rv != -EAGAIN) {
			dev_err(DEV, "%s_sendmsg returned %d\n",
			    sock == mdev->meta.socket ? "msock" : "sock",
			    rv);
			drbd_force_state(mdev, NS(conn, C_BROKEN_PIPE));
		} else
			drbd_force_state(mdev, NS(conn, C_TIMEOUT));
	}

	return sent;
}

static int drbd_open(struct block_device *bdev, fmode_t mode)
{
	struct drbd_conf *mdev = bdev->bd_disk->private_data;
	unsigned long flags;
	int rv = 0;

	mutex_lock(&drbd_main_mutex);
	spin_lock_irqsave(&mdev->req_lock, flags);
	/* to have a stable mdev->state.role
	 * and no race with updating open_cnt */

	if (mdev->state.role != R_PRIMARY) {
		if (mode & FMODE_WRITE)
			rv = -EROFS;
		else if (!allow_oos)
			rv = -EMEDIUMTYPE;
	}

	if (!rv)
		mdev->open_cnt++;
	spin_unlock_irqrestore(&mdev->req_lock, flags);
	mutex_unlock(&drbd_main_mutex);

	return rv;
}

static int drbd_release(struct gendisk *gd, fmode_t mode)
{
	struct drbd_conf *mdev = gd->private_data;
	mutex_lock(&drbd_main_mutex);
	mdev->open_cnt--;
	mutex_unlock(&drbd_main_mutex);
	return 0;
}

static void drbd_set_defaults(struct drbd_conf *mdev)
{
	/* This way we get a compile error when sync_conf grows,
	   and we forgot to initialize it here */
	mdev->sync_conf = (struct syncer_conf) {
		/* .rate = */		DRBD_RATE_DEF,
		/* .after = */		DRBD_AFTER_DEF,
		/* .al_extents = */	DRBD_AL_EXTENTS_DEF,
		/* .verify_alg = */	{}, 0,
		/* .cpu_mask = */	{}, 0,
		/* .csums_alg = */	{}, 0,
		/* .use_rle = */	0,
		/* .on_no_data = */	DRBD_ON_NO_DATA_DEF,
		/* .c_plan_ahead = */	DRBD_C_PLAN_AHEAD_DEF,
		/* .c_delay_target = */	DRBD_C_DELAY_TARGET_DEF,
		/* .c_fill_target = */	DRBD_C_FILL_TARGET_DEF,
		/* .c_max_rate = */	DRBD_C_MAX_RATE_DEF,
		/* .c_min_rate = */	DRBD_C_MIN_RATE_DEF
	};

	/* Have to use that way, because the layout differs between
	   big endian and little endian */
	mdev->state = (union drbd_state) {
		{ .role = R_SECONDARY,
		  .peer = R_UNKNOWN,
		  .conn = C_STANDALONE,
		  .disk = D_DISKLESS,
		  .pdsk = D_UNKNOWN,
		  .susp = 0,
		  .susp_nod = 0,
		  .susp_fen = 0
		} };
}

void drbd_init_set_defaults(struct drbd_conf *mdev)
{
	/* the memset(,0,) did most of this.
	 * note: only assignments, no allocation in here */

	drbd_set_defaults(mdev);

	atomic_set(&mdev->ap_bio_cnt, 0);
	atomic_set(&mdev->ap_pending_cnt, 0);
	atomic_set(&mdev->rs_pending_cnt, 0);
	atomic_set(&mdev->unacked_cnt, 0);
	atomic_set(&mdev->local_cnt, 0);
	atomic_set(&mdev->net_cnt, 0);
	atomic_set(&mdev->packet_seq, 0);
	atomic_set(&mdev->pp_in_use, 0);
	atomic_set(&mdev->pp_in_use_by_net, 0);
	atomic_set(&mdev->rs_sect_in, 0);
	atomic_set(&mdev->rs_sect_ev, 0);
	atomic_set(&mdev->ap_in_flight, 0);

	mutex_init(&mdev->md_io_mutex);
	mutex_init(&mdev->data.mutex);
	mutex_init(&mdev->meta.mutex);
	sema_init(&mdev->data.work.s, 0);
	sema_init(&mdev->meta.work.s, 0);
	mutex_init(&mdev->state_mutex);

	spin_lock_init(&mdev->data.work.q_lock);
	spin_lock_init(&mdev->meta.work.q_lock);

	spin_lock_init(&mdev->al_lock);
	spin_lock_init(&mdev->req_lock);
	spin_lock_init(&mdev->peer_seq_lock);
	spin_lock_init(&mdev->epoch_lock);

	INIT_LIST_HEAD(&mdev->active_ee);
	INIT_LIST_HEAD(&mdev->sync_ee);
	INIT_LIST_HEAD(&mdev->done_ee);
	INIT_LIST_HEAD(&mdev->read_ee);
	INIT_LIST_HEAD(&mdev->net_ee);
	INIT_LIST_HEAD(&mdev->resync_reads);
	INIT_LIST_HEAD(&mdev->data.work.q);
	INIT_LIST_HEAD(&mdev->meta.work.q);
	INIT_LIST_HEAD(&mdev->resync_work.list);
	INIT_LIST_HEAD(&mdev->unplug_work.list);
	INIT_LIST_HEAD(&mdev->go_diskless.list);
	INIT_LIST_HEAD(&mdev->md_sync_work.list);
	INIT_LIST_HEAD(&mdev->start_resync_work.list);
	INIT_LIST_HEAD(&mdev->bm_io_work.w.list);

	mdev->resync_work.cb  = w_resync_inactive;
	mdev->unplug_work.cb  = w_send_write_hint;
	mdev->go_diskless.cb  = w_go_diskless;
	mdev->md_sync_work.cb = w_md_sync;
	mdev->bm_io_work.w.cb = w_bitmap_io;
	init_timer(&mdev->resync_timer);
	init_timer(&mdev->md_sync_timer);
	mdev->resync_timer.function = resync_timer_fn;
	mdev->resync_timer.data = (unsigned long) mdev;
	mdev->md_sync_timer.function = md_sync_timer_fn;
	mdev->md_sync_timer.data = (unsigned long) mdev;

	init_waitqueue_head(&mdev->misc_wait);
	init_waitqueue_head(&mdev->state_wait);
	init_waitqueue_head(&mdev->net_cnt_wait);
	init_waitqueue_head(&mdev->ee_wait);
	init_waitqueue_head(&mdev->al_wait);
	init_waitqueue_head(&mdev->seq_wait);

	drbd_thread_init(mdev, &mdev->receiver, drbdd_init);
	drbd_thread_init(mdev, &mdev->worker, drbd_worker);
	drbd_thread_init(mdev, &mdev->asender, drbd_asender);

	mdev->agreed_pro_version = PRO_VERSION_MAX;
	mdev->write_ordering = WO_bdev_flush;
	mdev->resync_wenr = LC_FREE;
}

void drbd_mdev_cleanup(struct drbd_conf *mdev)
{
	int i;
	if (mdev->receiver.t_state != None)
		dev_err(DEV, "ASSERT FAILED: receiver t_state == %d expected 0.\n",
				mdev->receiver.t_state);

	/* no need to lock it, I'm the only thread alive */
	if (atomic_read(&mdev->current_epoch->epoch_size) !=  0)
		dev_err(DEV, "epoch_size:%d\n", atomic_read(&mdev->current_epoch->epoch_size));
	mdev->al_writ_cnt  =
	mdev->bm_writ_cnt  =
	mdev->read_cnt     =
	mdev->recv_cnt     =
	mdev->send_cnt     =
	mdev->writ_cnt     =
	mdev->p_size       =
	mdev->rs_start     =
	mdev->rs_total     =
	mdev->rs_failed    = 0;
	mdev->rs_last_events = 0;
	mdev->rs_last_sect_ev = 0;
	for (i = 0; i < DRBD_SYNC_MARKS; i++) {
		mdev->rs_mark_left[i] = 0;
		mdev->rs_mark_time[i] = 0;
	}
	D_ASSERT(mdev->net_conf == NULL);

	drbd_set_my_capacity(mdev, 0);
	if (mdev->bitmap) {
		/* maybe never allocated. */
		drbd_bm_resize(mdev, 0, 1);
		drbd_bm_cleanup(mdev);
	}

	drbd_free_resources(mdev);
	clear_bit(AL_SUSPENDED, &mdev->flags);

	/*
	 * currently we drbd_init_ee only on module load, so
	 * we may do drbd_release_ee only on module unload!
	 */
	D_ASSERT(list_empty(&mdev->active_ee));
	D_ASSERT(list_empty(&mdev->sync_ee));
	D_ASSERT(list_empty(&mdev->done_ee));
	D_ASSERT(list_empty(&mdev->read_ee));
	D_ASSERT(list_empty(&mdev->net_ee));
	D_ASSERT(list_empty(&mdev->resync_reads));
	D_ASSERT(list_empty(&mdev->data.work.q));
	D_ASSERT(list_empty(&mdev->meta.work.q));
	D_ASSERT(list_empty(&mdev->resync_work.list));
	D_ASSERT(list_empty(&mdev->unplug_work.list));
	D_ASSERT(list_empty(&mdev->go_diskless.list));
}


static void drbd_destroy_mempools(void)
{
	struct page *page;

	while (drbd_pp_pool) {
		page = drbd_pp_pool;
		drbd_pp_pool = (struct page *)page_private(page);
		__free_page(page);
		drbd_pp_vacant--;
	}

	/* D_ASSERT(atomic_read(&drbd_pp_vacant)==0); */

	if (drbd_ee_mempool)
		mempool_destroy(drbd_ee_mempool);
	if (drbd_request_mempool)
		mempool_destroy(drbd_request_mempool);
	if (drbd_ee_cache)
		kmem_cache_destroy(drbd_ee_cache);
	if (drbd_request_cache)
		kmem_cache_destroy(drbd_request_cache);
	if (drbd_bm_ext_cache)
		kmem_cache_destroy(drbd_bm_ext_cache);
	if (drbd_al_ext_cache)
		kmem_cache_destroy(drbd_al_ext_cache);

	drbd_ee_mempool      = NULL;
	drbd_request_mempool = NULL;
	drbd_ee_cache        = NULL;
	drbd_request_cache   = NULL;
	drbd_bm_ext_cache    = NULL;
	drbd_al_ext_cache    = NULL;

	return;
}

static int drbd_create_mempools(void)
{
	struct page *page;
	const int number = (DRBD_MAX_BIO_SIZE/PAGE_SIZE) * minor_count;
	int i;

	/* prepare our caches and mempools */
	drbd_request_mempool = NULL;
	drbd_ee_cache        = NULL;
	drbd_request_cache   = NULL;
	drbd_bm_ext_cache    = NULL;
	drbd_al_ext_cache    = NULL;
	drbd_pp_pool         = NULL;

	/* caches */
	drbd_request_cache = kmem_cache_create(
		"drbd_req", sizeof(struct drbd_request), 0, 0, NULL);
	if (drbd_request_cache == NULL)
		goto Enomem;

	drbd_ee_cache = kmem_cache_create(
		"drbd_ee", sizeof(struct drbd_epoch_entry), 0, 0, NULL);
	if (drbd_ee_cache == NULL)
		goto Enomem;

	drbd_bm_ext_cache = kmem_cache_create(
		"drbd_bm", sizeof(struct bm_extent), 0, 0, NULL);
	if (drbd_bm_ext_cache == NULL)
		goto Enomem;

	drbd_al_ext_cache = kmem_cache_create(
		"drbd_al", sizeof(struct lc_element), 0, 0, NULL);
	if (drbd_al_ext_cache == NULL)
		goto Enomem;

	/* mempools */
	drbd_request_mempool = mempool_create(number,
		mempool_alloc_slab, mempool_free_slab, drbd_request_cache);
	if (drbd_request_mempool == NULL)
		goto Enomem;

	drbd_ee_mempool = mempool_create(number,
		mempool_alloc_slab, mempool_free_slab, drbd_ee_cache);
	if (drbd_ee_mempool == NULL)
		goto Enomem;

	/* drbd's page pool */
	spin_lock_init(&drbd_pp_lock);

	for (i = 0; i < number; i++) {
		page = alloc_page(GFP_HIGHUSER);
		if (!page)
			goto Enomem;
		set_page_private(page, (unsigned long)drbd_pp_pool);
		drbd_pp_pool = page;
	}
	drbd_pp_vacant = number;

	return 0;

Enomem:
	drbd_destroy_mempools(); /* in case we allocated some */
	return -ENOMEM;
}

static int drbd_notify_sys(struct notifier_block *this, unsigned long code,
	void *unused)
{
	/* just so we have it.  you never know what interesting things we
	 * might want to do here some day...
	 */

	return NOTIFY_DONE;
}

static struct notifier_block drbd_notifier = {
	.notifier_call = drbd_notify_sys,
};

static void drbd_release_ee_lists(struct drbd_conf *mdev)
{
	int rr;

	rr = drbd_release_ee(mdev, &mdev->active_ee);
	if (rr)
		dev_err(DEV, "%d EEs in active list found!\n", rr);

	rr = drbd_release_ee(mdev, &mdev->sync_ee);
	if (rr)
		dev_err(DEV, "%d EEs in sync list found!\n", rr);

	rr = drbd_release_ee(mdev, &mdev->read_ee);
	if (rr)
		dev_err(DEV, "%d EEs in read list found!\n", rr);

	rr = drbd_release_ee(mdev, &mdev->done_ee);
	if (rr)
		dev_err(DEV, "%d EEs in done list found!\n", rr);

	rr = drbd_release_ee(mdev, &mdev->net_ee);
	if (rr)
		dev_err(DEV, "%d EEs in net list found!\n", rr);
}

/* caution. no locking.
 * currently only used from module cleanup code. */
static void drbd_delete_device(unsigned int minor)
{
	struct drbd_conf *mdev = minor_to_mdev(minor);

	if (!mdev)
		return;

	/* paranoia asserts */
	if (mdev->open_cnt != 0)
		dev_err(DEV, "open_cnt = %d in %s:%u", mdev->open_cnt,
				__FILE__ , __LINE__);

	ERR_IF (!list_empty(&mdev->data.work.q)) {
		struct list_head *lp;
		list_for_each(lp, &mdev->data.work.q) {
			dev_err(DEV, "lp = %p\n", lp);
		}
	};
	/* end paranoia asserts */

	del_gendisk(mdev->vdisk);

	/* cleanup stuff that may have been allocated during
	 * device (re-)configuration or state changes */

	if (mdev->this_bdev)
		bdput(mdev->this_bdev);

	drbd_free_resources(mdev);

	drbd_release_ee_lists(mdev);

	/* should be free'd on disconnect? */
	kfree(mdev->ee_hash);
	/*
	mdev->ee_hash_s = 0;
	mdev->ee_hash = NULL;
	*/

	lc_destroy(mdev->act_log);
	lc_destroy(mdev->resync);

	kfree(mdev->p_uuid);
	/* mdev->p_uuid = NULL; */

	kfree(mdev->int_dig_out);
	kfree(mdev->int_dig_in);
	kfree(mdev->int_dig_vv);

	/* cleanup the rest that has been
	 * allocated from drbd_new_device
	 * and actually free the mdev itself */
	drbd_free_mdev(mdev);
}

static void drbd_cleanup(void)
{
	unsigned int i;

	unregister_reboot_notifier(&drbd_notifier);

	/* first remove proc,
	 * drbdsetup uses it's presence to detect
	 * whether DRBD is loaded.
	 * If we would get stuck in proc removal,
	 * but have netlink already deregistered,
	 * some drbdsetup commands may wait forever
	 * for an answer.
	 */
	if (drbd_proc)
		remove_proc_entry("drbd", NULL);

	drbd_nl_cleanup();

	if (minor_table) {
		i = minor_count;
		while (i--)
			drbd_delete_device(i);
		drbd_destroy_mempools();
	}

	kfree(minor_table);

	unregister_blkdev(DRBD_MAJOR, "drbd");

	printk(KERN_INFO "drbd: module cleanup done.\n");
}

/**
 * drbd_congested() - Callback for pdflush
 * @congested_data:	User data
 * @bdi_bits:		Bits pdflush is currently interested in
 *
 * Returns 1<<BDI_async_congested and/or 1<<BDI_sync_congested if we are congested.
 */
static int drbd_congested(void *congested_data, int bdi_bits)
{
	struct drbd_conf *mdev = congested_data;
	struct request_queue *q;
	char reason = '-';
	int r = 0;

	if (!__inc_ap_bio_cond(mdev)) {
		/* DRBD has frozen IO */
		r = bdi_bits;
		reason = 'd';
		goto out;
	}

	if (get_ldev(mdev)) {
		q = bdev_get_queue(mdev->ldev->backing_bdev);
		r = bdi_congested(&q->backing_dev_info, bdi_bits);
		put_ldev(mdev);
		if (r)
			reason = 'b';
	}

	if (bdi_bits & (1 << BDI_async_congested) && test_bit(NET_CONGESTED, &mdev->flags)) {
		r |= (1 << BDI_async_congested);
		reason = reason == 'b' ? 'a' : 'n';
	}

out:
	mdev->congestion_reason = reason;
	return r;
}

struct drbd_conf *drbd_new_device(unsigned int minor)
{
	struct drbd_conf *mdev;
	struct gendisk *disk;
	struct request_queue *q;

	/* GFP_KERNEL, we are outside of all write-out paths */
	mdev = kzalloc(sizeof(struct drbd_conf), GFP_KERNEL);
	if (!mdev)
		return NULL;
	if (!zalloc_cpumask_var(&mdev->cpu_mask, GFP_KERNEL))
		goto out_no_cpumask;

	mdev->minor = minor;

	drbd_init_set_defaults(mdev);

	q = blk_alloc_queue(GFP_KERNEL);
	if (!q)
		goto out_no_q;
	mdev->rq_queue = q;
	q->queuedata   = mdev;

	disk = alloc_disk(1);
	if (!disk)
		goto out_no_disk;
	mdev->vdisk = disk;

	set_disk_ro(disk, true);

	disk->queue = q;
	disk->major = DRBD_MAJOR;
	disk->first_minor = minor;
	disk->fops = &drbd_ops;
	sprintf(disk->disk_name, "drbd%d", minor);
	disk->private_data = mdev;

	mdev->this_bdev = bdget(MKDEV(DRBD_MAJOR, minor));
	/* we have no partitions. we contain only ourselves. */
	mdev->this_bdev->bd_contains = mdev->this_bdev;

	q->backing_dev_info.congested_fn = drbd_congested;
	q->backing_dev_info.congested_data = mdev;

	blk_queue_make_request(q, drbd_make_request);
	blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE >> 9);
	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
	blk_queue_merge_bvec(q, drbd_merge_bvec);
	q->queue_lock = &mdev->req_lock;

	mdev->md_io_page = alloc_page(GFP_KERNEL);
	if (!mdev->md_io_page)
		goto out_no_io_page;

	if (drbd_bm_init(mdev))
		goto out_no_bitmap;
	/* no need to lock access, we are still initializing this minor device. */
	if (!tl_init(mdev))
		goto out_no_tl;

	mdev->app_reads_hash = kzalloc(APP_R_HSIZE*sizeof(void *), GFP_KERNEL);
	if (!mdev->app_reads_hash)
		goto out_no_app_reads;

	mdev->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
	if (!mdev->current_epoch)
		goto out_no_epoch;

	INIT_LIST_HEAD(&mdev->current_epoch->list);
	mdev->epochs = 1;

	return mdev;

/* out_whatever_else:
	kfree(mdev->current_epoch); */
out_no_epoch:
	kfree(mdev->app_reads_hash);
out_no_app_reads:
	tl_cleanup(mdev);
out_no_tl:
	drbd_bm_cleanup(mdev);
out_no_bitmap:
	__free_page(mdev->md_io_page);
out_no_io_page:
	put_disk(disk);
out_no_disk:
	blk_cleanup_queue(q);
out_no_q:
	free_cpumask_var(mdev->cpu_mask);
out_no_cpumask:
	kfree(mdev);
	return NULL;
}

/* counterpart of drbd_new_device.
 * last part of drbd_delete_device. */
void drbd_free_mdev(struct drbd_conf *mdev)
{
	kfree(mdev->current_epoch);
	kfree(mdev->app_reads_hash);
	tl_cleanup(mdev);
	if (mdev->bitmap) /* should no longer be there. */
		drbd_bm_cleanup(mdev);
	__free_page(mdev->md_io_page);
	put_disk(mdev->vdisk);
	blk_cleanup_queue(mdev->rq_queue);
	free_cpumask_var(mdev->cpu_mask);
	drbd_free_tl_hash(mdev);
	kfree(mdev);
}


int __init drbd_init(void)
{
	int err;

	if (sizeof(struct p_handshake) != 80) {
		printk(KERN_ERR
		       "drbd: never change the size or layout "
		       "of the HandShake packet.\n");
		return -EINVAL;
	}

	if (1 > minor_count || minor_count > 255) {
		printk(KERN_ERR
			"drbd: invalid minor_count (%d)\n", minor_count);
#ifdef MODULE
		return -EINVAL;
#else
		minor_count = 8;
#endif
	}

	err = drbd_nl_init();
	if (err)
		return err;

	err = register_blkdev(DRBD_MAJOR, "drbd");
	if (err) {
		printk(KERN_ERR
		       "drbd: unable to register block device major %d\n",
		       DRBD_MAJOR);
		return err;
	}

	register_reboot_notifier(&drbd_notifier);

	/*
	 * allocate all necessary structs
	 */
	err = -ENOMEM;

	init_waitqueue_head(&drbd_pp_wait);

	drbd_proc = NULL; /* play safe for drbd_cleanup */
	minor_table = kzalloc(sizeof(struct drbd_conf *)*minor_count,
				GFP_KERNEL);
	if (!minor_table)
		goto Enomem;

	err = drbd_create_mempools();
	if (err)
		goto Enomem;

	drbd_proc = proc_create_data("drbd", S_IFREG | S_IRUGO , NULL, &drbd_proc_fops, NULL);
	if (!drbd_proc)	{
		printk(KERN_ERR "drbd: unable to register proc file\n");
		goto Enomem;
	}

	rwlock_init(&global_state_lock);

	printk(KERN_INFO "drbd: initialized. "
	       "Version: " REL_VERSION " (api:%d/proto:%d-%d)\n",
	       API_VERSION, PRO_VERSION_MIN, PRO_VERSION_MAX);
	printk(KERN_INFO "drbd: %s\n", drbd_buildtag());
	printk(KERN_INFO "drbd: registered as block device major %d\n",
		DRBD_MAJOR);
	printk(KERN_INFO "drbd: minor_table @ 0x%p\n", minor_table);

	return 0; /* Success! */

Enomem:
	drbd_cleanup();
	if (err == -ENOMEM)
		/* currently always the case */
		printk(KERN_ERR "drbd: ran out of memory\n");
	else
		printk(KERN_ERR "drbd: initialization failure\n");
	return err;
}

void drbd_free_bc(struct drbd_backing_dev *ldev)
{
	if (ldev == NULL)
		return;

	blkdev_put(ldev->backing_bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
	blkdev_put(ldev->md_bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);

	kfree(ldev);
}

void drbd_free_sock(struct drbd_conf *mdev)
{
	if (mdev->data.socket) {
		mutex_lock(&mdev->data.mutex);
		kernel_sock_shutdown(mdev->data.socket, SHUT_RDWR);
		sock_release(mdev->data.socket);
		mdev->data.socket = NULL;
		mutex_unlock(&mdev->data.mutex);
	}
	if (mdev->meta.socket) {
		mutex_lock(&mdev->meta.mutex);
		kernel_sock_shutdown(mdev->meta.socket, SHUT_RDWR);
		sock_release(mdev->meta.socket);
		mdev->meta.socket = NULL;
		mutex_unlock(&mdev->meta.mutex);
	}
}


void drbd_free_resources(struct drbd_conf *mdev)
{
	crypto_free_hash(mdev->csums_tfm);
	mdev->csums_tfm = NULL;
	crypto_free_hash(mdev->verify_tfm);
	mdev->verify_tfm = NULL;
	crypto_free_hash(mdev->cram_hmac_tfm);
	mdev->cram_hmac_tfm = NULL;
	crypto_free_hash(mdev->integrity_w_tfm);
	mdev->integrity_w_tfm = NULL;
	crypto_free_hash(mdev->integrity_r_tfm);
	mdev->integrity_r_tfm = NULL;

	drbd_free_sock(mdev);

	__no_warn(local,
		  drbd_free_bc(mdev->ldev);
		  mdev->ldev = NULL;);
}

/* meta data management */

struct meta_data_on_disk {
	u64 la_size;           /* last agreed size. */
	u64 uuid[UI_SIZE];   /* UUIDs. */
	u64 device_uuid;
	u64 reserved_u64_1;
	u32 flags;             /* MDF */
	u32 magic;
	u32 md_size_sect;
	u32 al_offset;         /* offset to this block */
	u32 al_nr_extents;     /* important for restoring the AL */
	      /* `-- act_log->nr_elements <-- sync_conf.al_extents */
	u32 bm_offset;         /* offset to the bitmap, from here */
	u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
	u32 reserved_u32[4];

} __packed;

/**
 * drbd_md_sync() - Writes the meta data super block if the MD_DIRTY flag bit is set
 * @mdev:	DRBD device.
 */
void drbd_md_sync(struct drbd_conf *mdev)
{
	struct meta_data_on_disk *buffer;
	sector_t sector;
	int i;

	del_timer(&mdev->md_sync_timer);
	/* timer may be rearmed by drbd_md_mark_dirty() now. */
	if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
		return;

	/* We use here D_FAILED and not D_ATTACHING because we try to write
	 * metadata even if we detach due to a disk failure! */
	if (!get_ldev_if_state(mdev, D_FAILED))
		return;

	mutex_lock(&mdev->md_io_mutex);
	buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
	memset(buffer, 0, 512);

	buffer->la_size = cpu_to_be64(drbd_get_capacity(mdev->this_bdev));
	for (i = UI_CURRENT; i < UI_SIZE; i++)
		buffer->uuid[i] = cpu_to_be64(mdev->ldev->md.uuid[i]);
	buffer->flags = cpu_to_be32(mdev->ldev->md.flags);
	buffer->magic = cpu_to_be32(DRBD_MD_MAGIC);

	buffer->md_size_sect  = cpu_to_be32(mdev->ldev->md.md_size_sect);
	buffer->al_offset     = cpu_to_be32(mdev->ldev->md.al_offset);
	buffer->al_nr_extents = cpu_to_be32(mdev->act_log->nr_elements);
	buffer->bm_bytes_per_bit = cpu_to_be32(BM_BLOCK_SIZE);
	buffer->device_uuid = cpu_to_be64(mdev->ldev->md.device_uuid);

	buffer->bm_offset = cpu_to_be32(mdev->ldev->md.bm_offset);

	D_ASSERT(drbd_md_ss__(mdev, mdev->ldev) == mdev->ldev->md.md_offset);
	sector = mdev->ldev->md.md_offset;

	if (!drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
		/* this was a try anyways ... */
		dev_err(DEV, "meta data update failed!\n");
		drbd_chk_io_error(mdev, 1, true);
	}

	/* Update mdev->ldev->md.la_size_sect,
	 * since we updated it on metadata. */
	mdev->ldev->md.la_size_sect = drbd_get_capacity(mdev->this_bdev);

	mutex_unlock(&mdev->md_io_mutex);
	put_ldev(mdev);
}

/**
 * drbd_md_read() - Reads in the meta data super block
 * @mdev:	DRBD device.
 * @bdev:	Device from which the meta data should be read in.
 *
 * Return 0 (NO_ERROR) on success, and an enum drbd_ret_code in case
 * something goes wrong.  Currently only: ERR_IO_MD_DISK, ERR_MD_INVALID.
 */
int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
{
	struct meta_data_on_disk *buffer;
	int i, rv = NO_ERROR;

	if (!get_ldev_if_state(mdev, D_ATTACHING))
		return ERR_IO_MD_DISK;

	mutex_lock(&mdev->md_io_mutex);
	buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);

	if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
		/* NOTE: cant do normal error processing here as this is
		   called BEFORE disk is attached */
		dev_err(DEV, "Error while reading metadata.\n");
		rv = ERR_IO_MD_DISK;
		goto err;
	}

	if (be32_to_cpu(buffer->magic) != DRBD_MD_MAGIC) {
		dev_err(DEV, "Error while reading metadata, magic not found.\n");
		rv = ERR_MD_INVALID;
		goto err;
	}
	if (be32_to_cpu(buffer->al_offset) != bdev->md.al_offset) {
		dev_err(DEV, "unexpected al_offset: %d (expected %d)\n",
		    be32_to_cpu(buffer->al_offset), bdev->md.al_offset);
		rv = ERR_MD_INVALID;
		goto err;
	}
	if (be32_to_cpu(buffer->bm_offset) != bdev->md.bm_offset) {
		dev_err(DEV, "unexpected bm_offset: %d (expected %d)\n",
		    be32_to_cpu(buffer->bm_offset), bdev->md.bm_offset);
		rv = ERR_MD_INVALID;
		goto err;
	}
	if (be32_to_cpu(buffer->md_size_sect) != bdev->md.md_size_sect) {
		dev_err(DEV, "unexpected md_size: %u (expected %u)\n",
		    be32_to_cpu(buffer->md_size_sect), bdev->md.md_size_sect);
		rv = ERR_MD_INVALID;
		goto err;
	}

	if (be32_to_cpu(buffer->bm_bytes_per_bit) != BM_BLOCK_SIZE) {
		dev_err(DEV, "unexpected bm_bytes_per_bit: %u (expected %u)\n",
		    be32_to_cpu(buffer->bm_bytes_per_bit), BM_BLOCK_SIZE);
		rv = ERR_MD_INVALID;
		goto err;
	}

	bdev->md.la_size_sect = be64_to_cpu(buffer->la_size);
	for (i = UI_CURRENT; i < UI_SIZE; i++)
		bdev->md.uuid[i] = be64_to_cpu(buffer->uuid[i]);
	bdev->md.flags = be32_to_cpu(buffer->flags);
	mdev->sync_conf.al_extents = be32_to_cpu(buffer->al_nr_extents);
	bdev->md.device_uuid = be64_to_cpu(buffer->device_uuid);

	if (mdev->sync_conf.al_extents < 7)
		mdev->sync_conf.al_extents = 127;

 err:
	mutex_unlock(&mdev->md_io_mutex);
	put_ldev(mdev);

	return rv;
}

static void debug_drbd_uuid(struct drbd_conf *mdev, enum drbd_uuid_index index)
{
	static char *uuid_str[UI_EXTENDED_SIZE] = {
		[UI_CURRENT] = "CURRENT",
		[UI_BITMAP] = "BITMAP",
		[UI_HISTORY_START] = "HISTORY_START",
		[UI_HISTORY_END] = "HISTORY_END",
		[UI_SIZE] = "SIZE",
		[UI_FLAGS] = "FLAGS",
	};

	if (index >= UI_EXTENDED_SIZE) {
		dev_warn(DEV, " uuid_index >= EXTENDED_SIZE\n");
		return;
	}

	dynamic_dev_dbg(DEV, " uuid[%s] now %016llX\n",
		 uuid_str[index],
		 (unsigned long long)mdev->ldev->md.uuid[index]);
}


/**
 * drbd_md_mark_dirty() - Mark meta data super block as dirty
 * @mdev:	DRBD device.
 *
 * Call this function if you change anything that should be written to
 * the meta-data super block. This function sets MD_DIRTY, and starts a
 * timer that ensures that within five seconds you have to call drbd_md_sync().
 */
#ifdef DEBUG
void drbd_md_mark_dirty_(struct drbd_conf *mdev, unsigned int line, const char *func)
{
	if (!test_and_set_bit(MD_DIRTY, &mdev->flags)) {
		mod_timer(&mdev->md_sync_timer, jiffies + HZ);
		mdev->last_md_mark_dirty.line = line;
		mdev->last_md_mark_dirty.func = func;
	}
}
#else
void drbd_md_mark_dirty(struct drbd_conf *mdev)
{
	if (!test_and_set_bit(MD_DIRTY, &mdev->flags))
		mod_timer(&mdev->md_sync_timer, jiffies + 5*HZ);
}
#endif

static void drbd_uuid_move_history(struct drbd_conf *mdev) __must_hold(local)
{
	int i;

	for (i = UI_HISTORY_START; i < UI_HISTORY_END; i++) {
		mdev->ldev->md.uuid[i+1] = mdev->ldev->md.uuid[i];
		debug_drbd_uuid(mdev, i+1);
	}
}

void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
{
	if (idx == UI_CURRENT) {
		if (mdev->state.role == R_PRIMARY)
			val |= 1;
		else
			val &= ~((u64)1);

		drbd_set_ed_uuid(mdev, val);
	}

	mdev->ldev->md.uuid[idx] = val;
	debug_drbd_uuid(mdev, idx);
	drbd_md_mark_dirty(mdev);
}


void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
{
	if (mdev->ldev->md.uuid[idx]) {
		drbd_uuid_move_history(mdev);
		mdev->ldev->md.uuid[UI_HISTORY_START] = mdev->ldev->md.uuid[idx];
		debug_drbd_uuid(mdev, UI_HISTORY_START);
	}
	_drbd_uuid_set(mdev, idx, val);
}

/**
 * drbd_uuid_new_current() - Creates a new current UUID
 * @mdev:	DRBD device.
 *
 * Creates a new current UUID, and rotates the old current UUID into
 * the bitmap slot. Causes an incremental resync upon next connect.
 */
void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local)
{
	u64 val;

	dev_info(DEV, "Creating new current UUID\n");
	D_ASSERT(mdev->ldev->md.uuid[UI_BITMAP] == 0);
	mdev->ldev->md.uuid[UI_BITMAP] = mdev->ldev->md.uuid[UI_CURRENT];
	debug_drbd_uuid(mdev, UI_BITMAP);

	get_random_bytes(&val, sizeof(u64));
	_drbd_uuid_set(mdev, UI_CURRENT, val);
	/* get it to stable storage _now_ */
	drbd_md_sync(mdev);
}

void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local)
{
	if (mdev->ldev->md.uuid[UI_BITMAP] == 0 && val == 0)
		return;

	if (val == 0) {
		drbd_uuid_move_history(mdev);
		mdev->ldev->md.uuid[UI_HISTORY_START] = mdev->ldev->md.uuid[UI_BITMAP];
		mdev->ldev->md.uuid[UI_BITMAP] = 0;
		debug_drbd_uuid(mdev, UI_HISTORY_START);
		debug_drbd_uuid(mdev, UI_BITMAP);
	} else {
		if (mdev->ldev->md.uuid[UI_BITMAP])
			dev_warn(DEV, "bm UUID already set");

		mdev->ldev->md.uuid[UI_BITMAP] = val;
		mdev->ldev->md.uuid[UI_BITMAP] &= ~((u64)1);

		debug_drbd_uuid(mdev, UI_BITMAP);
	}
	drbd_md_mark_dirty(mdev);
}

/**
 * drbd_bmio_set_n_write() - io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io()
 * @mdev:	DRBD device.
 *
 * Sets all bits in the bitmap and writes the whole bitmap to stable storage.
 */
int drbd_bmio_set_n_write(struct drbd_conf *mdev)
{
	int rv = -EIO;

	if (get_ldev_if_state(mdev, D_ATTACHING)) {
		drbd_md_set_flag(mdev, MDF_FULL_SYNC);
		drbd_md_sync(mdev);
		drbd_bm_set_all(mdev);

		rv = drbd_bm_write(mdev);

		if (!rv) {
			drbd_md_clear_flag(mdev, MDF_FULL_SYNC);
			drbd_md_sync(mdev);
		}

		put_ldev(mdev);
	}

	return rv;
}

/**
 * drbd_bmio_clear_n_write() - io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io()
 * @mdev:	DRBD device.
 *
 * Clears all bits in the bitmap and writes the whole bitmap to stable storage.
 */
int drbd_bmio_clear_n_write(struct drbd_conf *mdev)
{
	int rv = -EIO;

	drbd_resume_al(mdev);
	if (get_ldev_if_state(mdev, D_ATTACHING)) {
		drbd_bm_clear_all(mdev);
		rv = drbd_bm_write(mdev);
		put_ldev(mdev);
	}

	return rv;
}

static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
{
	struct bm_io_work *work = container_of(w, struct bm_io_work, w);
	int rv;

	D_ASSERT(atomic_read(&mdev->ap_bio_cnt) == 0);

	drbd_bm_lock(mdev, work->why);
	rv = work->io_fn(mdev);
	drbd_bm_unlock(mdev);

	clear_bit(BITMAP_IO, &mdev->flags);
	smp_mb__after_clear_bit();
	wake_up(&mdev->misc_wait);

	if (work->done)
		work->done(mdev, rv);

	clear_bit(BITMAP_IO_QUEUED, &mdev->flags);
	work->why = NULL;

	return 1;
}

void drbd_ldev_destroy(struct drbd_conf *mdev)
{
	lc_destroy(mdev->resync);
	mdev->resync = NULL;
	lc_destroy(mdev->act_log);
	mdev->act_log = NULL;
	__no_warn(local,
		drbd_free_bc(mdev->ldev);
		mdev->ldev = NULL;);

	if (mdev->md_io_tmpp) {
		__free_page(mdev->md_io_tmpp);
		mdev->md_io_tmpp = NULL;
	}
	clear_bit(GO_DISKLESS, &mdev->flags);
}

static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused)
{
	D_ASSERT(mdev->state.disk == D_FAILED);
	/* we cannot assert local_cnt == 0 here, as get_ldev_if_state will
	 * inc/dec it frequently. Once we are D_DISKLESS, no one will touch
	 * the protected members anymore, though, so once put_ldev reaches zero
	 * again, it will be safe to free them. */
	drbd_force_state(mdev, NS(disk, D_DISKLESS));
	return 1;
}

void drbd_go_diskless(struct drbd_conf *mdev)
{
	D_ASSERT(mdev->state.disk == D_FAILED);
	if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
		drbd_queue_work(&mdev->data.work, &mdev->go_diskless);
}

/**
 * drbd_queue_bitmap_io() - Queues an IO operation on the whole bitmap
 * @mdev:	DRBD device.
 * @io_fn:	IO callback to be called when bitmap IO is possible
 * @done:	callback to be called after the bitmap IO was performed
 * @why:	Descriptive text of the reason for doing the IO
 *
 * While IO on the bitmap happens we freeze application IO thus we ensure
 * that drbd_set_out_of_sync() can not be called. This function MAY ONLY be
 * called from worker context. It MUST NOT be used while a previous such
 * work is still pending!
 */
void drbd_queue_bitmap_io(struct drbd_conf *mdev,
			  int (*io_fn)(struct drbd_conf *),
			  void (*done)(struct drbd_conf *, int),
			  char *why)
{
	D_ASSERT(current == mdev->worker.task);

	D_ASSERT(!test_bit(BITMAP_IO_QUEUED, &mdev->flags));
	D_ASSERT(!test_bit(BITMAP_IO, &mdev->flags));
	D_ASSERT(list_empty(&mdev->bm_io_work.w.list));
	if (mdev->bm_io_work.why)
		dev_err(DEV, "FIXME going to queue '%s' but '%s' still pending?\n",
			why, mdev->bm_io_work.why);

	mdev->bm_io_work.io_fn = io_fn;
	mdev->bm_io_work.done = done;
	mdev->bm_io_work.why = why;

	spin_lock_irq(&mdev->req_lock);
	set_bit(BITMAP_IO, &mdev->flags);
	if (atomic_read(&mdev->ap_bio_cnt) == 0) {
		if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
			drbd_queue_work(&mdev->data.work, &mdev->bm_io_work.w);
	}
	spin_unlock_irq(&mdev->req_lock);
}

/**
 * drbd_bitmap_io() -  Does an IO operation on the whole bitmap
 * @mdev:	DRBD device.
 * @io_fn:	IO callback to be called when bitmap IO is possible
 * @why:	Descriptive text of the reason for doing the IO
 *
 * freezes application IO while that the actual IO operations runs. This
 * functions MAY NOT be called from worker context.
 */
int drbd_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *), char *why)
{
	int rv;

	D_ASSERT(current != mdev->worker.task);

	drbd_suspend_io(mdev);

	drbd_bm_lock(mdev, why);
	rv = io_fn(mdev);
	drbd_bm_unlock(mdev);

	drbd_resume_io(mdev);

	return rv;
}

void drbd_md_set_flag(struct drbd_conf *mdev, int flag) __must_hold(local)
{
	if ((mdev->ldev->md.flags & flag) != flag) {
		drbd_md_mark_dirty(mdev);
		mdev->ldev->md.flags |= flag;
	}
}

void drbd_md_clear_flag(struct drbd_conf *mdev, int flag) __must_hold(local)
{
	if ((mdev->ldev->md.flags & flag) != 0) {
		drbd_md_mark_dirty(mdev);
		mdev->ldev->md.flags &= ~flag;
	}
}
int drbd_md_test_flag(struct drbd_backing_dev *bdev, int flag)
{
	return (bdev->md.flags & flag) != 0;
}

static void md_sync_timer_fn(unsigned long data)
{
	struct drbd_conf *mdev = (struct drbd_conf *) data;

	drbd_queue_work_front(&mdev->data.work, &mdev->md_sync_work);
}

static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused)
{
	dev_warn(DEV, "md_sync_timer expired! Worker calls drbd_md_sync().\n");
#ifdef DEBUG
	dev_warn(DEV, "last md_mark_dirty: %s:%u\n",
		mdev->last_md_mark_dirty.func, mdev->last_md_mark_dirty.line);
#endif
	drbd_md_sync(mdev);
	return 1;
}

#ifdef CONFIG_DRBD_FAULT_INJECTION
/* Fault insertion support including random number generator shamelessly
 * stolen from kernel/rcutorture.c */
struct fault_random_state {
	unsigned long state;
	unsigned long count;
};

#define FAULT_RANDOM_MULT 39916801  /* prime */
#define FAULT_RANDOM_ADD	479001701 /* prime */
#define FAULT_RANDOM_REFRESH 10000

/*
 * Crude but fast random-number generator.  Uses a linear congruential
 * generator, with occasional help from get_random_bytes().
 */
static unsigned long
_drbd_fault_random(struct fault_random_state *rsp)
{
	long refresh;

	if (!rsp->count--) {
		get_random_bytes(&refresh, sizeof(refresh));
		rsp->state += refresh;
		rsp->count = FAULT_RANDOM_REFRESH;
	}
	rsp->state = rsp->state * FAULT_RANDOM_MULT + FAULT_RANDOM_ADD;
	return swahw32(rsp->state);
}

static char *
_drbd_fault_str(unsigned int type) {
	static char *_faults[] = {
		[DRBD_FAULT_MD_WR] = "Meta-data write",
		[DRBD_FAULT_MD_RD] = "Meta-data read",
		[DRBD_FAULT_RS_WR] = "Resync write",
		[DRBD_FAULT_RS_RD] = "Resync read",
		[DRBD_FAULT_DT_WR] = "Data write",
		[DRBD_FAULT_DT_RD] = "Data read",
		[DRBD_FAULT_DT_RA] = "Data read ahead",
		[DRBD_FAULT_BM_ALLOC] = "BM allocation",
		[DRBD_FAULT_AL_EE] = "EE allocation",
		[DRBD_FAULT_RECEIVE] = "receive data corruption",
	};

	return (type < DRBD_FAULT_MAX) ? _faults[type] : "**Unknown**";
}

unsigned int
_drbd_insert_fault(struct drbd_conf *mdev, unsigned int type)
{
	static struct fault_random_state rrs = {0, 0};

	unsigned int ret = (
		(fault_devs == 0 ||
			((1 << mdev_to_minor(mdev)) & fault_devs) != 0) &&
		(((_drbd_fault_random(&rrs) % 100) + 1) <= fault_rate));

	if (ret) {
		fault_count++;

		if (__ratelimit(&drbd_ratelimit_state))
			dev_warn(DEV, "***Simulating %s failure\n",
				_drbd_fault_str(type));
	}

	return ret;
}
#endif

const char *drbd_buildtag(void)
{
	/* DRBD built from external sources has here a reference to the
	   git hash of the source code. */

	static char buildtag[38] = "\0uilt-in";

	if (buildtag[0] == 0) {
#ifdef CONFIG_MODULES
		if (THIS_MODULE != NULL)
			sprintf(buildtag, "srcversion: %-24s", THIS_MODULE->srcversion);
		else
#endif
			buildtag[0] = 'b';
	}

	return buildtag;
}

module_init(drbd_init)
module_exit(drbd_cleanup)

EXPORT_SYMBOL(drbd_conn_str);
EXPORT_SYMBOL(drbd_role_str);
EXPORT_SYMBOL(drbd_disk_str);
EXPORT_SYMBOL(drbd_set_st_err_str);