aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/block/drbd/drbd_receiver.c
blob: 3f096e7959b44ad44f990edeac2a118808a73c06 (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
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
/*
   drbd_receiver.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>.

   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 <asm/uaccess.h>
#include <net/sock.h>

#include <linux/drbd.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/in.h>
#include <linux/mm.h>
#include <linux/memcontrol.h>
#include <linux/mm_inline.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/pkt_sched.h>
#define __KERNEL_SYSCALLS__
#include <linux/unistd.h>
#include <linux/vmalloc.h>
#include <linux/random.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/scatterlist.h>
#include "drbd_int.h"
#include "drbd_req.h"

#include "drbd_vli.h"

struct flush_work {
	struct drbd_work w;
	struct drbd_epoch *epoch;
};

enum finish_epoch {
	FE_STILL_LIVE,
	FE_DESTROYED,
	FE_RECYCLED,
};

static int drbd_do_handshake(struct drbd_conf *mdev);
static int drbd_do_auth(struct drbd_conf *mdev);

static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *, struct drbd_epoch *, enum epoch_event);
static int e_end_block(struct drbd_conf *, struct drbd_work *, int);

static struct drbd_epoch *previous_epoch(struct drbd_conf *mdev, struct drbd_epoch *epoch)
{
	struct drbd_epoch *prev;
	spin_lock(&mdev->epoch_lock);
	prev = list_entry(epoch->list.prev, struct drbd_epoch, list);
	if (prev == epoch || prev == mdev->current_epoch)
		prev = NULL;
	spin_unlock(&mdev->epoch_lock);
	return prev;
}

#define GFP_TRY	(__GFP_HIGHMEM | __GFP_NOWARN)

static struct page *drbd_pp_first_page_or_try_alloc(struct drbd_conf *mdev)
{
	struct page *page = NULL;

	/* Yes, testing drbd_pp_vacant outside the lock is racy.
	 * So what. It saves a spin_lock. */
	if (drbd_pp_vacant > 0) {
		spin_lock(&drbd_pp_lock);
		page = drbd_pp_pool;
		if (page) {
			drbd_pp_pool = (struct page *)page_private(page);
			set_page_private(page, 0); /* just to be polite */
			drbd_pp_vacant--;
		}
		spin_unlock(&drbd_pp_lock);
	}
	/* GFP_TRY, because we must not cause arbitrary write-out: in a DRBD
	 * "criss-cross" setup, that might cause write-out on some other DRBD,
	 * which in turn might block on the other node at this very place.  */
	if (!page)
		page = alloc_page(GFP_TRY);
	if (page)
		atomic_inc(&mdev->pp_in_use);
	return page;
}

/* kick lower level device, if we have more than (arbitrary number)
 * reference counts on it, which typically are locally submitted io
 * requests.  don't use unacked_cnt, so we speed up proto A and B, too. */
static void maybe_kick_lo(struct drbd_conf *mdev)
{
	if (atomic_read(&mdev->local_cnt) >= mdev->net_conf->unplug_watermark)
		drbd_kick_lo(mdev);
}

static void reclaim_net_ee(struct drbd_conf *mdev, struct list_head *to_be_freed)
{
	struct drbd_epoch_entry *e;
	struct list_head *le, *tle;

	/* The EEs are always appended to the end of the list. Since
	   they are sent in order over the wire, they have to finish
	   in order. As soon as we see the first not finished we can
	   stop to examine the list... */

	list_for_each_safe(le, tle, &mdev->net_ee) {
		e = list_entry(le, struct drbd_epoch_entry, w.list);
		if (drbd_bio_has_active_page(e->private_bio))
			break;
		list_move(le, to_be_freed);
	}
}

static void drbd_kick_lo_and_reclaim_net(struct drbd_conf *mdev)
{
	LIST_HEAD(reclaimed);
	struct drbd_epoch_entry *e, *t;

	maybe_kick_lo(mdev);
	spin_lock_irq(&mdev->req_lock);
	reclaim_net_ee(mdev, &reclaimed);
	spin_unlock_irq(&mdev->req_lock);

	list_for_each_entry_safe(e, t, &reclaimed, w.list)
		drbd_free_ee(mdev, e);
}

/**
 * drbd_pp_alloc() - Returns a page, fails only if a signal comes in
 * @mdev:	DRBD device.
 * @retry:	whether or not to retry allocation forever (or until signalled)
 *
 * Tries to allocate a page, first from our own page pool, then from the
 * kernel, unless this allocation would exceed the max_buffers setting.
 * If @retry is non-zero, retry until DRBD frees a page somewhere else.
 */
static struct page *drbd_pp_alloc(struct drbd_conf *mdev, int retry)
{
	struct page *page = NULL;
	DEFINE_WAIT(wait);

	if (atomic_read(&mdev->pp_in_use) < mdev->net_conf->max_buffers) {
		page = drbd_pp_first_page_or_try_alloc(mdev);
		if (page)
			return page;
	}

	for (;;) {
		prepare_to_wait(&drbd_pp_wait, &wait, TASK_INTERRUPTIBLE);

		drbd_kick_lo_and_reclaim_net(mdev);

		if (atomic_read(&mdev->pp_in_use) < mdev->net_conf->max_buffers) {
			page = drbd_pp_first_page_or_try_alloc(mdev);
			if (page)
				break;
		}

		if (!retry)
			break;

		if (signal_pending(current)) {
			dev_warn(DEV, "drbd_pp_alloc interrupted!\n");
			break;
		}

		schedule();
	}
	finish_wait(&drbd_pp_wait, &wait);

	return page;
}

/* Must not be used from irq, as that may deadlock: see drbd_pp_alloc.
 * Is also used from inside an other spin_lock_irq(&mdev->req_lock) */
static void drbd_pp_free(struct drbd_conf *mdev, struct page *page)
{
	int free_it;

	spin_lock(&drbd_pp_lock);
	if (drbd_pp_vacant > (DRBD_MAX_SEGMENT_SIZE/PAGE_SIZE)*minor_count) {
		free_it = 1;
	} else {
		set_page_private(page, (unsigned long)drbd_pp_pool);
		drbd_pp_pool = page;
		drbd_pp_vacant++;
		free_it = 0;
	}
	spin_unlock(&drbd_pp_lock);

	atomic_dec(&mdev->pp_in_use);

	if (free_it)
		__free_page(page);

	wake_up(&drbd_pp_wait);
}

static void drbd_pp_free_bio_pages(struct drbd_conf *mdev, struct bio *bio)
{
	struct page *p_to_be_freed = NULL;
	struct page *page;
	struct bio_vec *bvec;
	int i;

	spin_lock(&drbd_pp_lock);
	__bio_for_each_segment(bvec, bio, i, 0) {
		if (drbd_pp_vacant > (DRBD_MAX_SEGMENT_SIZE/PAGE_SIZE)*minor_count) {
			set_page_private(bvec->bv_page, (unsigned long)p_to_be_freed);
			p_to_be_freed = bvec->bv_page;
		} else {
			set_page_private(bvec->bv_page, (unsigned long)drbd_pp_pool);
			drbd_pp_pool = bvec->bv_page;
			drbd_pp_vacant++;
		}
	}
	spin_unlock(&drbd_pp_lock);
	atomic_sub(bio->bi_vcnt, &mdev->pp_in_use);

	while (p_to_be_freed) {
		page = p_to_be_freed;
		p_to_be_freed = (struct page *)page_private(page);
		set_page_private(page, 0); /* just to be polite */
		put_page(page);
	}

	wake_up(&drbd_pp_wait);
}

/*
You need to hold the req_lock:
 _drbd_wait_ee_list_empty()

You must not have the req_lock:
 drbd_free_ee()
 drbd_alloc_ee()
 drbd_init_ee()
 drbd_release_ee()
 drbd_ee_fix_bhs()
 drbd_process_done_ee()
 drbd_clear_done_ee()
 drbd_wait_ee_list_empty()
*/

struct drbd_epoch_entry *drbd_alloc_ee(struct drbd_conf *mdev,
				     u64 id,
				     sector_t sector,
				     unsigned int data_size,
				     gfp_t gfp_mask) __must_hold(local)
{
	struct request_queue *q;
	struct drbd_epoch_entry *e;
	struct page *page;
	struct bio *bio;
	unsigned int ds;

	if (FAULT_ACTIVE(mdev, DRBD_FAULT_AL_EE))
		return NULL;

	e = mempool_alloc(drbd_ee_mempool, gfp_mask & ~__GFP_HIGHMEM);
	if (!e) {
		if (!(gfp_mask & __GFP_NOWARN))
			dev_err(DEV, "alloc_ee: Allocation of an EE failed\n");
		return NULL;
	}

	bio = bio_alloc(gfp_mask & ~__GFP_HIGHMEM, div_ceil(data_size, PAGE_SIZE));
	if (!bio) {
		if (!(gfp_mask & __GFP_NOWARN))
			dev_err(DEV, "alloc_ee: Allocation of a bio failed\n");
		goto fail1;
	}

	bio->bi_bdev = mdev->ldev->backing_bdev;
	bio->bi_sector = sector;

	ds = data_size;
	while (ds) {
		page = drbd_pp_alloc(mdev, (gfp_mask & __GFP_WAIT));
		if (!page) {
			if (!(gfp_mask & __GFP_NOWARN))
				dev_err(DEV, "alloc_ee: Allocation of a page failed\n");
			goto fail2;
		}
		if (!bio_add_page(bio, page, min_t(int, ds, PAGE_SIZE), 0)) {
			drbd_pp_free(mdev, page);
			dev_err(DEV, "alloc_ee: bio_add_page(s=%llu,"
			    "data_size=%u,ds=%u) failed\n",
			    (unsigned long long)sector, data_size, ds);

			q = bdev_get_queue(bio->bi_bdev);
			if (q->merge_bvec_fn) {
				struct bvec_merge_data bvm = {
					.bi_bdev = bio->bi_bdev,
					.bi_sector = bio->bi_sector,
					.bi_size = bio->bi_size,
					.bi_rw = bio->bi_rw,
				};
				int l = q->merge_bvec_fn(q, &bvm,
						&bio->bi_io_vec[bio->bi_vcnt]);
				dev_err(DEV, "merge_bvec_fn() = %d\n", l);
			}

			/* dump more of the bio. */
			dev_err(DEV, "bio->bi_max_vecs = %d\n", bio->bi_max_vecs);
			dev_err(DEV, "bio->bi_vcnt = %d\n", bio->bi_vcnt);
			dev_err(DEV, "bio->bi_size = %d\n", bio->bi_size);
			dev_err(DEV, "bio->bi_phys_segments = %d\n", bio->bi_phys_segments);

			goto fail2;
			break;
		}
		ds -= min_t(int, ds, PAGE_SIZE);
	}

	D_ASSERT(data_size == bio->bi_size);

	bio->bi_private = e;
	e->mdev = mdev;
	e->sector = sector;
	e->size = bio->bi_size;

	e->private_bio = bio;
	e->block_id = id;
	INIT_HLIST_NODE(&e->colision);
	e->epoch = NULL;
	e->flags = 0;

	return e;

 fail2:
	drbd_pp_free_bio_pages(mdev, bio);
	bio_put(bio);
 fail1:
	mempool_free(e, drbd_ee_mempool);

	return NULL;
}

void drbd_free_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
{
	struct bio *bio = e->private_bio;
	drbd_pp_free_bio_pages(mdev, bio);
	bio_put(bio);
	D_ASSERT(hlist_unhashed(&e->colision));
	mempool_free(e, drbd_ee_mempool);
}

int drbd_release_ee(struct drbd_conf *mdev, struct list_head *list)
{
	LIST_HEAD(work_list);
	struct drbd_epoch_entry *e, *t;
	int count = 0;

	spin_lock_irq(&mdev->req_lock);
	list_splice_init(list, &work_list);
	spin_unlock_irq(&mdev->req_lock);

	list_for_each_entry_safe(e, t, &work_list, w.list) {
		drbd_free_ee(mdev, e);
		count++;
	}
	return count;
}


/*
 * This function is called from _asender only_
 * but see also comments in _req_mod(,barrier_acked)
 * and receive_Barrier.
 *
 * Move entries from net_ee to done_ee, if ready.
 * Grab done_ee, call all callbacks, free the entries.
 * The callbacks typically send out ACKs.
 */
static int drbd_process_done_ee(struct drbd_conf *mdev)
{
	LIST_HEAD(work_list);
	LIST_HEAD(reclaimed);
	struct drbd_epoch_entry *e, *t;
	int ok = (mdev->state.conn >= C_WF_REPORT_PARAMS);

	spin_lock_irq(&mdev->req_lock);
	reclaim_net_ee(mdev, &reclaimed);
	list_splice_init(&mdev->done_ee, &work_list);
	spin_unlock_irq(&mdev->req_lock);

	list_for_each_entry_safe(e, t, &reclaimed, w.list)
		drbd_free_ee(mdev, e);

	/* possible callbacks here:
	 * e_end_block, and e_end_resync_block, e_send_discard_ack.
	 * all ignore the last argument.
	 */
	list_for_each_entry_safe(e, t, &work_list, w.list) {
		/* list_del not necessary, next/prev members not touched */
		ok = e->w.cb(mdev, &e->w, !ok) && ok;
		drbd_free_ee(mdev, e);
	}
	wake_up(&mdev->ee_wait);

	return ok;
}

void _drbd_wait_ee_list_empty(struct drbd_conf *mdev, struct list_head *head)
{
	DEFINE_WAIT(wait);

	/* avoids spin_lock/unlock
	 * and calling prepare_to_wait in the fast path */
	while (!list_empty(head)) {
		prepare_to_wait(&mdev->ee_wait, &wait, TASK_UNINTERRUPTIBLE);
		spin_unlock_irq(&mdev->req_lock);
		drbd_kick_lo(mdev);
		schedule();
		finish_wait(&mdev->ee_wait, &wait);
		spin_lock_irq(&mdev->req_lock);
	}
}

void drbd_wait_ee_list_empty(struct drbd_conf *mdev, struct list_head *head)
{
	spin_lock_irq(&mdev->req_lock);
	_drbd_wait_ee_list_empty(mdev, head);
	spin_unlock_irq(&mdev->req_lock);
}

/* see also kernel_accept; which is only present since 2.6.18.
 * also we want to log which part of it failed, exactly */
static int drbd_accept(struct drbd_conf *mdev, const char **what,
		struct socket *sock, struct socket **newsock)
{
	struct sock *sk = sock->sk;
	int err = 0;

	*what = "listen";
	err = sock->ops->listen(sock, 5);
	if (err < 0)
		goto out;

	*what = "sock_create_lite";
	err = sock_create_lite(sk->sk_family, sk->sk_type, sk->sk_protocol,
			       newsock);
	if (err < 0)
		goto out;

	*what = "accept";
	err = sock->ops->accept(sock, *newsock, 0);
	if (err < 0) {
		sock_release(*newsock);
		*newsock = NULL;
		goto out;
	}
	(*newsock)->ops  = sock->ops;

out:
	return err;
}

static int drbd_recv_short(struct drbd_conf *mdev, struct socket *sock,
		    void *buf, size_t size, int flags)
{
	mm_segment_t oldfs;
	struct kvec iov = {
		.iov_base = buf,
		.iov_len = size,
	};
	struct msghdr msg = {
		.msg_iovlen = 1,
		.msg_iov = (struct iovec *)&iov,
		.msg_flags = (flags ? flags : MSG_WAITALL | MSG_NOSIGNAL)
	};
	int rv;

	oldfs = get_fs();
	set_fs(KERNEL_DS);
	rv = sock_recvmsg(sock, &msg, size, msg.msg_flags);
	set_fs(oldfs);

	return rv;
}

static int drbd_recv(struct drbd_conf *mdev, void *buf, size_t size)
{
	mm_segment_t oldfs;
	struct kvec iov = {
		.iov_base = buf,
		.iov_len = size,
	};
	struct msghdr msg = {
		.msg_iovlen = 1,
		.msg_iov = (struct iovec *)&iov,
		.msg_flags = MSG_WAITALL | MSG_NOSIGNAL
	};
	int rv;

	oldfs = get_fs();
	set_fs(KERNEL_DS);

	for (;;) {
		rv = sock_recvmsg(mdev->data.socket, &msg, size, msg.msg_flags);
		if (rv == size)
			break;

		/* Note:
		 * ECONNRESET	other side closed the connection
		 * ERESTARTSYS	(on  sock) we got a signal
		 */

		if (rv < 0) {
			if (rv == -ECONNRESET)
				dev_info(DEV, "sock was reset by peer\n");
			else if (rv != -ERESTARTSYS)
				dev_err(DEV, "sock_recvmsg returned %d\n", rv);
			break;
		} else if (rv == 0) {
			dev_info(DEV, "sock was shut down by peer\n");
			break;
		} else	{
			/* signal came in, or peer/link went down,
			 * after we read a partial message
			 */
			/* D_ASSERT(signal_pending(current)); */
			break;
		}
	};

	set_fs(oldfs);

	if (rv != size)
		drbd_force_state(mdev, NS(conn, C_BROKEN_PIPE));

	return rv;
}

static struct socket *drbd_try_connect(struct drbd_conf *mdev)
{
	const char *what;
	struct socket *sock;
	struct sockaddr_in6 src_in6;
	int err;
	int disconnect_on_error = 1;

	if (!get_net_conf(mdev))
		return NULL;

	what = "sock_create_kern";
	err = sock_create_kern(((struct sockaddr *)mdev->net_conf->my_addr)->sa_family,
		SOCK_STREAM, IPPROTO_TCP, &sock);
	if (err < 0) {
		sock = NULL;
		goto out;
	}

	sock->sk->sk_rcvtimeo =
	sock->sk->sk_sndtimeo =  mdev->net_conf->try_connect_int*HZ;

       /* explicitly bind to the configured IP as source IP
	*  for the outgoing connections.
	*  This is needed for multihomed hosts and to be
	*  able to use lo: interfaces for drbd.
	* Make sure to use 0 as port number, so linux selects
	*  a free one dynamically.
	*/
	memcpy(&src_in6, mdev->net_conf->my_addr,
	       min_t(int, mdev->net_conf->my_addr_len, sizeof(src_in6)));
	if (((struct sockaddr *)mdev->net_conf->my_addr)->sa_family == AF_INET6)
		src_in6.sin6_port = 0;
	else
		((struct sockaddr_in *)&src_in6)->sin_port = 0; /* AF_INET & AF_SCI */

	what = "bind before connect";
	err = sock->ops->bind(sock,
			      (struct sockaddr *) &src_in6,
			      mdev->net_conf->my_addr_len);
	if (err < 0)
		goto out;

	/* connect may fail, peer not yet available.
	 * stay C_WF_CONNECTION, don't go Disconnecting! */
	disconnect_on_error = 0;
	what = "connect";
	err = sock->ops->connect(sock,
				 (struct sockaddr *)mdev->net_conf->peer_addr,
				 mdev->net_conf->peer_addr_len, 0);

out:
	if (err < 0) {
		if (sock) {
			sock_release(sock);
			sock = NULL;
		}
		switch (-err) {
			/* timeout, busy, signal pending */
		case ETIMEDOUT: case EAGAIN: case EINPROGRESS:
		case EINTR: case ERESTARTSYS:
			/* peer not (yet) available, network problem */
		case ECONNREFUSED: case ENETUNREACH:
		case EHOSTDOWN:    case EHOSTUNREACH:
			disconnect_on_error = 0;
			break;
		default:
			dev_err(DEV, "%s failed, err = %d\n", what, err);
		}
		if (disconnect_on_error)
			drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
	}
	put_net_conf(mdev);
	return sock;
}

static struct socket *drbd_wait_for_connect(struct drbd_conf *mdev)
{
	int timeo, err;
	struct socket *s_estab = NULL, *s_listen;
	const char *what;

	if (!get_net_conf(mdev))
		return NULL;

	what = "sock_create_kern";
	err = sock_create_kern(((struct sockaddr *)mdev->net_conf->my_addr)->sa_family,
		SOCK_STREAM, IPPROTO_TCP, &s_listen);
	if (err) {
		s_listen = NULL;
		goto out;
	}

	timeo = mdev->net_conf->try_connect_int * HZ;
	timeo += (random32() & 1) ? timeo / 7 : -timeo / 7; /* 28.5% random jitter */

	s_listen->sk->sk_reuse    = 1; /* SO_REUSEADDR */
	s_listen->sk->sk_rcvtimeo = timeo;
	s_listen->sk->sk_sndtimeo = timeo;

	what = "bind before listen";
	err = s_listen->ops->bind(s_listen,
			      (struct sockaddr *) mdev->net_conf->my_addr,
			      mdev->net_conf->my_addr_len);
	if (err < 0)
		goto out;

	err = drbd_accept(mdev, &what, s_listen, &s_estab);

out:
	if (s_listen)
		sock_release(s_listen);
	if (err < 0) {
		if (err != -EAGAIN && err != -EINTR && err != -ERESTARTSYS) {
			dev_err(DEV, "%s failed, err = %d\n", what, err);
			drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
		}
	}
	put_net_conf(mdev);

	return s_estab;
}

static int drbd_send_fp(struct drbd_conf *mdev,
	struct socket *sock, enum drbd_packets cmd)
{
	struct p_header *h = (struct p_header *) &mdev->data.sbuf.header;

	return _drbd_send_cmd(mdev, sock, cmd, h, sizeof(*h), 0);
}

static enum drbd_packets drbd_recv_fp(struct drbd_conf *mdev, struct socket *sock)
{
	struct p_header *h = (struct p_header *) &mdev->data.sbuf.header;
	int rr;

	rr = drbd_recv_short(mdev, sock, h, sizeof(*h), 0);

	if (rr == sizeof(*h) && h->magic == BE_DRBD_MAGIC)
		return be16_to_cpu(h->command);

	return 0xffff;
}

/**
 * drbd_socket_okay() - Free the socket if its connection is not okay
 * @mdev:	DRBD device.
 * @sock:	pointer to the pointer to the socket.
 */
static int drbd_socket_okay(struct drbd_conf *mdev, struct socket **sock)
{
	int rr;
	char tb[4];

	if (!*sock)
		return FALSE;

	rr = drbd_recv_short(mdev, *sock, tb, 4, MSG_DONTWAIT | MSG_PEEK);

	if (rr > 0 || rr == -EAGAIN) {
		return TRUE;
	} else {
		sock_release(*sock);
		*sock = NULL;
		return FALSE;
	}
}

/*
 * return values:
 *   1 yes, we have a valid connection
 *   0 oops, did not work out, please try again
 *  -1 peer talks different language,
 *     no point in trying again, please go standalone.
 *  -2 We do not have a network config...
 */
static int drbd_connect(struct drbd_conf *mdev)
{
	struct socket *s, *sock, *msock;
	int try, h, ok;

	D_ASSERT(!mdev->data.socket);

	if (test_and_clear_bit(CREATE_BARRIER, &mdev->flags))
		dev_err(DEV, "CREATE_BARRIER flag was set in drbd_connect - now cleared!\n");

	if (drbd_request_state(mdev, NS(conn, C_WF_CONNECTION)) < SS_SUCCESS)
		return -2;

	clear_bit(DISCARD_CONCURRENT, &mdev->flags);

	sock  = NULL;
	msock = NULL;

	do {
		for (try = 0;;) {
			/* 3 tries, this should take less than a second! */
			s = drbd_try_connect(mdev);
			if (s || ++try >= 3)
				break;
			/* give the other side time to call bind() & listen() */
			__set_current_state(TASK_INTERRUPTIBLE);
			schedule_timeout(HZ / 10);
		}

		if (s) {
			if (!sock) {
				drbd_send_fp(mdev, s, P_HAND_SHAKE_S);
				sock = s;
				s = NULL;
			} else if (!msock) {
				drbd_send_fp(mdev, s, P_HAND_SHAKE_M);
				msock = s;
				s = NULL;
			} else {
				dev_err(DEV, "Logic error in drbd_connect()\n");
				goto out_release_sockets;
			}
		}

		if (sock && msock) {
			__set_current_state(TASK_INTERRUPTIBLE);
			schedule_timeout(HZ / 10);
			ok = drbd_socket_okay(mdev, &sock);
			ok = drbd_socket_okay(mdev, &msock) && ok;
			if (ok)
				break;
		}

retry:
		s = drbd_wait_for_connect(mdev);
		if (s) {
			try = drbd_recv_fp(mdev, s);
			drbd_socket_okay(mdev, &sock);
			drbd_socket_okay(mdev, &msock);
			switch (try) {
			case P_HAND_SHAKE_S:
				if (sock) {
					dev_warn(DEV, "initial packet S crossed\n");
					sock_release(sock);
				}
				sock = s;
				break;
			case P_HAND_SHAKE_M:
				if (msock) {
					dev_warn(DEV, "initial packet M crossed\n");
					sock_release(msock);
				}
				msock = s;
				set_bit(DISCARD_CONCURRENT, &mdev->flags);
				break;
			default:
				dev_warn(DEV, "Error receiving initial packet\n");
				sock_release(s);
				if (random32() & 1)
					goto retry;
			}
		}

		if (mdev->state.conn <= C_DISCONNECTING)
			goto out_release_sockets;
		if (signal_pending(current)) {
			flush_signals(current);
			smp_rmb();
			if (get_t_state(&mdev->receiver) == Exiting)
				goto out_release_sockets;
		}

		if (sock && msock) {
			ok = drbd_socket_okay(mdev, &sock);
			ok = drbd_socket_okay(mdev, &msock) && ok;
			if (ok)
				break;
		}
	} while (1);

	msock->sk->sk_reuse = 1; /* SO_REUSEADDR */
	sock->sk->sk_reuse = 1; /* SO_REUSEADDR */

	sock->sk->sk_allocation = GFP_NOIO;
	msock->sk->sk_allocation = GFP_NOIO;

	sock->sk->sk_priority = TC_PRIO_INTERACTIVE_BULK;
	msock->sk->sk_priority = TC_PRIO_INTERACTIVE;

	if (mdev->net_conf->sndbuf_size) {
		sock->sk->sk_sndbuf = mdev->net_conf->sndbuf_size;
		sock->sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
	}

	if (mdev->net_conf->rcvbuf_size) {
		sock->sk->sk_rcvbuf = mdev->net_conf->rcvbuf_size;
		sock->sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
	}

	/* NOT YET ...
	 * sock->sk->sk_sndtimeo = mdev->net_conf->timeout*HZ/10;
	 * sock->sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;
	 * first set it to the P_HAND_SHAKE timeout,
	 * which we set to 4x the configured ping_timeout. */
	sock->sk->sk_sndtimeo =
	sock->sk->sk_rcvtimeo = mdev->net_conf->ping_timeo*4*HZ/10;

	msock->sk->sk_sndtimeo = mdev->net_conf->timeout*HZ/10;
	msock->sk->sk_rcvtimeo = mdev->net_conf->ping_int*HZ;

	/* we don't want delays.
	 * we use TCP_CORK where apropriate, though */
	drbd_tcp_nodelay(sock);
	drbd_tcp_nodelay(msock);

	mdev->data.socket = sock;
	mdev->meta.socket = msock;
	mdev->last_received = jiffies;

	D_ASSERT(mdev->asender.task == NULL);

	h = drbd_do_handshake(mdev);
	if (h <= 0)
		return h;

	if (mdev->cram_hmac_tfm) {
		/* drbd_request_state(mdev, NS(conn, WFAuth)); */
		switch (drbd_do_auth(mdev)) {
		case -1:
			dev_err(DEV, "Authentication of peer failed\n");
			return -1;
		case 0:
			dev_err(DEV, "Authentication of peer failed, trying again.\n");
			return 0;
		}
	}

	if (drbd_request_state(mdev, NS(conn, C_WF_REPORT_PARAMS)) < SS_SUCCESS)
		return 0;

	sock->sk->sk_sndtimeo = mdev->net_conf->timeout*HZ/10;
	sock->sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;

	atomic_set(&mdev->packet_seq, 0);
	mdev->peer_seq = 0;

	drbd_thread_start(&mdev->asender);

	if (!drbd_send_protocol(mdev))
		return -1;
	drbd_send_sync_param(mdev, &mdev->sync_conf);
	drbd_send_sizes(mdev, 0);
	drbd_send_uuids(mdev);
	drbd_send_state(mdev);
	clear_bit(USE_DEGR_WFC_T, &mdev->flags);
	clear_bit(RESIZE_PENDING, &mdev->flags);

	return 1;

out_release_sockets:
	if (sock)
		sock_release(sock);
	if (msock)
		sock_release(msock);
	return -1;
}

static int drbd_recv_header(struct drbd_conf *mdev, struct p_header *h)
{
	int r;

	r = drbd_recv(mdev, h, sizeof(*h));

	if (unlikely(r != sizeof(*h))) {
		dev_err(DEV, "short read expecting header on sock: r=%d\n", r);
		return FALSE;
	};
	h->command = be16_to_cpu(h->command);
	h->length  = be16_to_cpu(h->length);
	if (unlikely(h->magic != BE_DRBD_MAGIC)) {
		dev_err(DEV, "magic?? on data m: 0x%lx c: %d l: %d\n",
		    (long)be32_to_cpu(h->magic),
		    h->command, h->length);
		return FALSE;
	}
	mdev->last_received = jiffies;

	return TRUE;
}

static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct drbd_epoch *epoch)
{
	int rv;

	if (mdev->write_ordering >= WO_bdev_flush && get_ldev(mdev)) {
		rv = blkdev_issue_flush(mdev->ldev->backing_bdev, NULL);
		if (rv) {
			dev_err(DEV, "local disk flush failed with status %d\n", rv);
			/* would rather check on EOPNOTSUPP, but that is not reliable.
			 * don't try again for ANY return value != 0
			 * if (rv == -EOPNOTSUPP) */
			drbd_bump_write_ordering(mdev, WO_drain_io);
		}
		put_ldev(mdev);
	}

	return drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE);
}

static int w_flush(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
{
	struct flush_work *fw = (struct flush_work *)w;
	struct drbd_epoch *epoch = fw->epoch;

	kfree(w);

	if (!test_and_set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags))
		drbd_flush_after_epoch(mdev, epoch);

	drbd_may_finish_epoch(mdev, epoch, EV_PUT |
			      (mdev->state.conn < C_CONNECTED ? EV_CLEANUP : 0));

	return 1;
}

/**
 * drbd_may_finish_epoch() - Applies an epoch_event to the epoch's state, eventually finishes it.
 * @mdev:	DRBD device.
 * @epoch:	Epoch object.
 * @ev:		Epoch event.
 */
static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
					       struct drbd_epoch *epoch,
					       enum epoch_event ev)
{
	int finish, epoch_size;
	struct drbd_epoch *next_epoch;
	int schedule_flush = 0;
	enum finish_epoch rv = FE_STILL_LIVE;

	spin_lock(&mdev->epoch_lock);
	do {
		next_epoch = NULL;
		finish = 0;

		epoch_size = atomic_read(&epoch->epoch_size);

		switch (ev & ~EV_CLEANUP) {
		case EV_PUT:
			atomic_dec(&epoch->active);
			break;
		case EV_GOT_BARRIER_NR:
			set_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags);

			/* Special case: If we just switched from WO_bio_barrier to
			   WO_bdev_flush we should not finish the current epoch */
			if (test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags) && epoch_size == 1 &&
			    mdev->write_ordering != WO_bio_barrier &&
			    epoch == mdev->current_epoch)
				clear_bit(DE_CONTAINS_A_BARRIER, &epoch->flags);
			break;
		case EV_BARRIER_DONE:
			set_bit(DE_BARRIER_IN_NEXT_EPOCH_DONE, &epoch->flags);
			break;
		case EV_BECAME_LAST:
			/* nothing to do*/
			break;
		}

		if (epoch_size != 0 &&
		    atomic_read(&epoch->active) == 0 &&
		    test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags) &&
		    epoch->list.prev == &mdev->current_epoch->list &&
		    !test_bit(DE_IS_FINISHING, &epoch->flags)) {
			/* Nearly all conditions are met to finish that epoch... */
			if (test_bit(DE_BARRIER_IN_NEXT_EPOCH_DONE, &epoch->flags) ||
			    mdev->write_ordering == WO_none ||
			    (epoch_size == 1 && test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags)) ||
			    ev & EV_CLEANUP) {
				finish = 1;
				set_bit(DE_IS_FINISHING, &epoch->flags);
			} else if (!test_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags) &&
				 mdev->write_ordering == WO_bio_barrier) {
				atomic_inc(&epoch->active);
				schedule_flush = 1;
			}
		}
		if (finish) {
			if (!(ev & EV_CLEANUP)) {
				spin_unlock(&mdev->epoch_lock);
				drbd_send_b_ack(mdev, epoch->barrier_nr, epoch_size);
				spin_lock(&mdev->epoch_lock);
			}
			dec_unacked(mdev);

			if (mdev->current_epoch != epoch) {
				next_epoch = list_entry(epoch->list.next, struct drbd_epoch, list);
				list_del(&epoch->list);
				ev = EV_BECAME_LAST | (ev & EV_CLEANUP);
				mdev->epochs--;
				kfree(epoch);

				if (rv == FE_STILL_LIVE)
					rv = FE_DESTROYED;
			} else {
				epoch->flags = 0;
				atomic_set(&epoch->epoch_size, 0);
				/* atomic_set(&epoch->active, 0); is alrady zero */
				if (rv == FE_STILL_LIVE)
					rv = FE_RECYCLED;
			}
		}

		if (!next_epoch)
			break;

		epoch = next_epoch;
	} while (1);

	spin_unlock(&mdev->epoch_lock);

	if (schedule_flush) {
		struct flush_work *fw;
		fw = kmalloc(sizeof(*fw), GFP_ATOMIC);
		if (fw) {
			fw->w.cb = w_flush;
			fw->epoch = epoch;
			drbd_queue_work(&mdev->data.work, &fw->w);
		} else {
			dev_warn(DEV, "Could not kmalloc a flush_work obj\n");
			set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags);
			/* That is not a recursion, only one level */
			drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE);
			drbd_may_finish_epoch(mdev, epoch, EV_PUT);
		}
	}

	return rv;
}

/**
 * drbd_bump_write_ordering() - Fall back to an other write ordering method
 * @mdev:	DRBD device.
 * @wo:		Write ordering method to try.
 */
void drbd_bump_write_ordering(struct drbd_conf *mdev, enum write_ordering_e wo) __must_hold(local)
{
	enum write_ordering_e pwo;
	static char *write_ordering_str[] = {
		[WO_none] = "none",
		[WO_drain_io] = "drain",
		[WO_bdev_flush] = "flush",
		[WO_bio_barrier] = "barrier",
	};

	pwo = mdev->write_ordering;
	wo = min(pwo, wo);
	if (wo == WO_bio_barrier && mdev->ldev->dc.no_disk_barrier)
		wo = WO_bdev_flush;
	if (wo == WO_bdev_flush && mdev->ldev->dc.no_disk_flush)
		wo = WO_drain_io;
	if (wo == WO_drain_io && mdev->ldev->dc.no_disk_drain)
		wo = WO_none;
	mdev->write_ordering = wo;
	if (pwo != mdev->write_ordering || wo == WO_bio_barrier)
		dev_info(DEV, "Method to ensure write ordering: %s\n", write_ordering_str[mdev->write_ordering]);
}

/**
 * w_e_reissue() - Worker callback; Resubmit a bio, without BIO_RW_BARRIER set
 * @mdev:	DRBD device.
 * @w:		work object.
 * @cancel:	The connection will be closed anyways (unused in this callback)
 */
int w_e_reissue(struct drbd_conf *mdev, struct drbd_work *w, int cancel) __releases(local)
{
	struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
	struct bio *bio = e->private_bio;

	/* We leave DE_CONTAINS_A_BARRIER and EE_IS_BARRIER in place,
	   (and DE_BARRIER_IN_NEXT_EPOCH_ISSUED in the previous Epoch)
	   so that we can finish that epoch in drbd_may_finish_epoch().
	   That is necessary if we already have a long chain of Epochs, before
	   we realize that BIO_RW_BARRIER is actually not supported */

	/* As long as the -ENOTSUPP on the barrier is reported immediately
	   that will never trigger. If it is reported late, we will just
	   print that warning and continue correctly for all future requests
	   with WO_bdev_flush */
	if (previous_epoch(mdev, e->epoch))
		dev_warn(DEV, "Write ordering was not enforced (one time event)\n");

	/* prepare bio for re-submit,
	 * re-init volatile members */
	/* we still have a local reference,
	 * get_ldev was done in receive_Data. */
	bio->bi_bdev = mdev->ldev->backing_bdev;
	bio->bi_sector = e->sector;
	bio->bi_size = e->size;
	bio->bi_idx = 0;

	bio->bi_flags &= ~(BIO_POOL_MASK - 1);
	bio->bi_flags |= 1 << BIO_UPTODATE;

	/* don't know whether this is necessary: */
	bio->bi_phys_segments = 0;
	bio->bi_next = NULL;

	/* these should be unchanged: */
	/* bio->bi_end_io = drbd_endio_write_sec; */
	/* bio->bi_vcnt = whatever; */

	e->w.cb = e_end_block;

	/* This is no longer a barrier request. */
	bio->bi_rw &= ~(1UL << BIO_RW_BARRIER);

	drbd_generic_make_request(mdev, DRBD_FAULT_DT_WR, bio);

	return 1;
}

static int receive_Barrier(struct drbd_conf *mdev, struct p_header *h)
{
	int rv, issue_flush;
	struct p_barrier *p = (struct p_barrier *)h;
	struct drbd_epoch *epoch;

	ERR_IF(h->length != (sizeof(*p)-sizeof(*h))) return FALSE;

	rv = drbd_recv(mdev, h->payload, h->length);
	ERR_IF(rv != h->length) return FALSE;

	inc_unacked(mdev);

	if (mdev->net_conf->wire_protocol != DRBD_PROT_C)
		drbd_kick_lo(mdev);

	mdev->current_epoch->barrier_nr = p->barrier;
	rv = drbd_may_finish_epoch(mdev, mdev->current_epoch, EV_GOT_BARRIER_NR);

	/* P_BARRIER_ACK may imply that the corresponding extent is dropped from
	 * the activity log, which means it would not be resynced in case the
	 * R_PRIMARY crashes now.
	 * Therefore we must send the barrier_ack after the barrier request was
	 * completed. */
	switch (mdev->write_ordering) {
	case WO_bio_barrier:
	case WO_none:
		if (rv == FE_RECYCLED)
			return TRUE;
		break;

	case WO_bdev_flush:
	case WO_drain_io:
		if (rv == FE_STILL_LIVE) {
			set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &mdev->current_epoch->flags);
			drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
			rv = drbd_flush_after_epoch(mdev, mdev->current_epoch);
		}
		if (rv == FE_RECYCLED)
			return TRUE;

		/* The asender will send all the ACKs and barrier ACKs out, since
		   all EEs moved from the active_ee to the done_ee. We need to
		   provide a new epoch object for the EEs that come in soon */
		break;
	}

	/* receiver context, in the writeout path of the other node.
	 * avoid potential distributed deadlock */
	epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
	if (!epoch) {
		dev_warn(DEV, "Allocation of an epoch failed, slowing down\n");
		issue_flush = !test_and_set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &mdev->current_epoch->flags);
		drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
		if (issue_flush) {
			rv = drbd_flush_after_epoch(mdev, mdev->current_epoch);
			if (rv == FE_RECYCLED)
				return TRUE;
		}

		drbd_wait_ee_list_empty(mdev, &mdev->done_ee);

		return TRUE;
	}

	epoch->flags = 0;
	atomic_set(&epoch->epoch_size, 0);
	atomic_set(&epoch->active, 0);

	spin_lock(&mdev->epoch_lock);
	if (atomic_read(&mdev->current_epoch->epoch_size)) {
		list_add(&epoch->list, &mdev->current_epoch->list);
		mdev->current_epoch = epoch;
		mdev->epochs++;
	} else {
		/* The current_epoch got recycled while we allocated this one... */
		kfree(epoch);
	}
	spin_unlock(&mdev->epoch_lock);

	return TRUE;
}

/* used from receive_RSDataReply (recv_resync_read)
 * and from receive_Data */
static struct drbd_epoch_entry *
read_in_block(struct drbd_conf *mdev, u64 id, sector_t sector, int data_size) __must_hold(local)
{
	struct drbd_epoch_entry *e;
	struct bio_vec *bvec;
	struct page *page;
	struct bio *bio;
	int dgs, ds, i, rr;
	void *dig_in = mdev->int_dig_in;
	void *dig_vv = mdev->int_dig_vv;

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

	if (dgs) {
		rr = drbd_recv(mdev, dig_in, dgs);
		if (rr != dgs) {
			dev_warn(DEV, "short read receiving data digest: read %d expected %d\n",
			     rr, dgs);
			return NULL;
		}
	}

	data_size -= dgs;

	ERR_IF(data_size &  0x1ff) return NULL;
	ERR_IF(data_size >  DRBD_MAX_SEGMENT_SIZE) return NULL;

	/* GFP_NOIO, because we must not cause arbitrary write-out: in a DRBD
	 * "criss-cross" setup, that might cause write-out on some other DRBD,
	 * which in turn might block on the other node at this very place.  */
	e = drbd_alloc_ee(mdev, id, sector, data_size, GFP_NOIO);
	if (!e)
		return NULL;
	bio = e->private_bio;
	ds = data_size;
	bio_for_each_segment(bvec, bio, i) {
		page = bvec->bv_page;
		rr = drbd_recv(mdev, kmap(page), min_t(int, ds, PAGE_SIZE));
		kunmap(page);
		if (rr != min_t(int, ds, PAGE_SIZE)) {
			drbd_free_ee(mdev, e);
			dev_warn(DEV, "short read receiving data: read %d expected %d\n",
			     rr, min_t(int, ds, PAGE_SIZE));
			return NULL;
		}
		ds -= rr;
	}

	if (dgs) {
		drbd_csum(mdev, mdev->integrity_r_tfm, bio, dig_vv);
		if (memcmp(dig_in, dig_vv, dgs)) {
			dev_err(DEV, "Digest integrity check FAILED.\n");
			drbd_bcast_ee(mdev, "digest failed",
					dgs, dig_in, dig_vv, e);
			drbd_free_ee(mdev, e);
			return NULL;
		}
	}
	mdev->recv_cnt += data_size>>9;
	return e;
}

/* drbd_drain_block() just takes a data block
 * out of the socket input buffer, and discards it.
 */
static int drbd_drain_block(struct drbd_conf *mdev, int data_size)
{
	struct page *page;
	int rr, rv = 1;
	void *data;

	page = drbd_pp_alloc(mdev, 1);

	data = kmap(page);
	while (data_size) {
		rr = drbd_recv(mdev, data, min_t(int, data_size, PAGE_SIZE));
		if (rr != min_t(int, data_size, PAGE_SIZE)) {
			rv = 0;
			dev_warn(DEV, "short read receiving data: read %d expected %d\n",
			     rr, min_t(int, data_size, PAGE_SIZE));
			break;
		}
		data_size -= rr;
	}
	kunmap(page);
	drbd_pp_free(mdev, page);
	return rv;
}

static int recv_dless_read(struct drbd_conf *mdev, struct drbd_request *req,
			   sector_t sector, int data_size)
{
	struct bio_vec *bvec;
	struct bio *bio;
	int dgs, rr, i, expect;
	void *dig_in = mdev->int_dig_in;
	void *dig_vv = mdev->int_dig_vv;

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

	if (dgs) {
		rr = drbd_recv(mdev, dig_in, dgs);
		if (rr != dgs) {
			dev_warn(DEV, "short read receiving data reply digest: read %d expected %d\n",
			     rr, dgs);
			return 0;
		}
	}

	data_size -= dgs;

	/* optimistically update recv_cnt.  if receiving fails below,
	 * we disconnect anyways, and counters will be reset. */
	mdev->recv_cnt += data_size>>9;

	bio = req->master_bio;
	D_ASSERT(sector == bio->bi_sector);

	bio_for_each_segment(bvec, bio, i) {
		expect = min_t(int, data_size, bvec->bv_len);
		rr = drbd_recv(mdev,
			     kmap(bvec->bv_page)+bvec->bv_offset,
			     expect);
		kunmap(bvec->bv_page);
		if (rr != expect) {
			dev_warn(DEV, "short read receiving data reply: "
			     "read %d expected %d\n",
			     rr, expect);
			return 0;
		}
		data_size -= rr;
	}

	if (dgs) {
		drbd_csum(mdev, mdev->integrity_r_tfm, bio, dig_vv);
		if (memcmp(dig_in, dig_vv, dgs)) {
			dev_err(DEV, "Digest integrity check FAILED. Broken NICs?\n");
			return 0;
		}
	}

	D_ASSERT(data_size == 0);
	return 1;
}

/* e_end_resync_block() is called via
 * drbd_process_done_ee() by asender only */
static int e_end_resync_block(struct drbd_conf *mdev, struct drbd_work *w, int unused)
{
	struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
	sector_t sector = e->sector;
	int ok;

	D_ASSERT(hlist_unhashed(&e->colision));

	if (likely(drbd_bio_uptodate(e->private_bio))) {
		drbd_set_in_sync(mdev, sector, e->size);
		ok = drbd_send_ack(mdev, P_RS_WRITE_ACK, e);
	} else {
		/* Record failure to sync */
		drbd_rs_failed_io(mdev, sector, e->size);

		ok  = drbd_send_ack(mdev, P_NEG_ACK, e);
	}
	dec_unacked(mdev);

	return ok;
}

static int recv_resync_read(struct drbd_conf *mdev, sector_t sector, int data_size) __releases(local)
{
	struct drbd_epoch_entry *e;

	e = read_in_block(mdev, ID_SYNCER, sector, data_size);
	if (!e) {
		put_ldev(mdev);
		return FALSE;
	}

	dec_rs_pending(mdev);

	e->private_bio->bi_end_io = drbd_endio_write_sec;
	e->private_bio->bi_rw = WRITE;
	e->w.cb = e_end_resync_block;

	inc_unacked(mdev);
	/* corresponding dec_unacked() in e_end_resync_block()
	 * respective _drbd_clear_done_ee */

	spin_lock_irq(&mdev->req_lock);
	list_add(&e->w.list, &mdev->sync_ee);
	spin_unlock_irq(&mdev->req_lock);

	drbd_generic_make_request(mdev, DRBD_FAULT_RS_WR, e->private_bio);
	/* accounting done in endio */

	maybe_kick_lo(mdev);
	return TRUE;
}

static int receive_DataReply(struct drbd_conf *mdev, struct p_header *h)
{
	struct drbd_request *req;
	sector_t sector;
	unsigned int header_size, data_size;
	int ok;
	struct p_data *p = (struct p_data *)h;

	header_size = sizeof(*p) - sizeof(*h);
	data_size   = h->length  - header_size;

	ERR_IF(data_size == 0) return FALSE;

	if (drbd_recv(mdev, h->payload, header_size) != header_size)
		return FALSE;

	sector = be64_to_cpu(p->sector);

	spin_lock_irq(&mdev->req_lock);
	req = _ar_id_to_req(mdev, p->block_id, sector);
	spin_unlock_irq(&mdev->req_lock);
	if (unlikely(!req)) {
		dev_err(DEV, "Got a corrupt block_id/sector pair(1).\n");
		return FALSE;
	}

	/* hlist_del(&req->colision) is done in _req_may_be_done, to avoid
	 * special casing it there for the various failure cases.
	 * still no race with drbd_fail_pending_reads */
	ok = recv_dless_read(mdev, req, sector, data_size);

	if (ok)
		req_mod(req, data_received);
	/* else: nothing. handled from drbd_disconnect...
	 * I don't think we may complete this just yet
	 * in case we are "on-disconnect: freeze" */

	return ok;
}

static int receive_RSDataReply(struct drbd_conf *mdev, struct p_header *h)
{
	sector_t sector;
	unsigned int header_size, data_size;
	int ok;
	struct p_data *p = (struct p_data *)h;

	header_size = sizeof(*p) - sizeof(*h);
	data_size   = h->length  - header_size;

	ERR_IF(data_size == 0) return FALSE;

	if (drbd_recv(mdev, h->payload, header_size) != header_size)
		return FALSE;

	sector = be64_to_cpu(p->sector);
	D_ASSERT(p->block_id == ID_SYNCER);

	if (get_ldev(mdev)) {
		/* data is submitted to disk within recv_resync_read.
		 * corresponding put_ldev done below on error,
		 * or in drbd_endio_write_sec. */
		ok = recv_resync_read(mdev, sector, data_size);
	} else {
		if (__ratelimit(&drbd_ratelimit_state))
			dev_err(DEV, "Can not write resync data to local disk.\n");

		ok = drbd_drain_block(mdev, data_size);

		drbd_send_ack_dp(mdev, P_NEG_ACK, p);
	}

	return ok;
}

/* e_end_block() is called via drbd_process_done_ee().
 * this means this function only runs in the asender thread
 */
static int e_end_block(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
{
	struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
	sector_t sector = e->sector;
	struct drbd_epoch *epoch;
	int ok = 1, pcmd;

	if (e->flags & EE_IS_BARRIER) {
		epoch = previous_epoch(mdev, e->epoch);
		if (epoch)
			drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE + (cancel ? EV_CLEANUP : 0));
	}

	if (mdev->net_conf->wire_protocol == DRBD_PROT_C) {
		if (likely(drbd_bio_uptodate(e->private_bio))) {
			pcmd = (mdev->state.conn >= C_SYNC_SOURCE &&
				mdev->state.conn <= C_PAUSED_SYNC_T &&
				e->flags & EE_MAY_SET_IN_SYNC) ?
				P_RS_WRITE_ACK : P_WRITE_ACK;
			ok &= drbd_send_ack(mdev, pcmd, e);
			if (pcmd == P_RS_WRITE_ACK)
				drbd_set_in_sync(mdev, sector, e->size);
		} else {
			ok  = drbd_send_ack(mdev, P_NEG_ACK, e);
			/* we expect it to be marked out of sync anyways...
			 * maybe assert this?  */
		}
		dec_unacked(mdev);
	}
	/* we delete from the conflict detection hash _after_ we sent out the
	 * P_WRITE_ACK / P_NEG_ACK, to get the sequence number right.  */
	if (mdev->net_conf->two_primaries) {
		spin_lock_irq(&mdev->req_lock);
		D_ASSERT(!hlist_unhashed(&e->colision));
		hlist_del_init(&e->colision);
		spin_unlock_irq(&mdev->req_lock);
	} else {
		D_ASSERT(hlist_unhashed(&e->colision));
	}

	drbd_may_finish_epoch(mdev, e->epoch, EV_PUT + (cancel ? EV_CLEANUP : 0));

	return ok;
}

static int e_send_discard_ack(struct drbd_conf *mdev, struct drbd_work *w, int unused)
{
	struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
	int ok = 1;

	D_ASSERT(mdev->net_conf->wire_protocol == DRBD_PROT_C);
	ok = drbd_send_ack(mdev, P_DISCARD_ACK, e);

	spin_lock_irq(&mdev->req_lock);
	D_ASSERT(!hlist_unhashed(&e->colision));
	hlist_del_init(&e->colision);
	spin_unlock_irq(&mdev->req_lock);

	dec_unacked(mdev);

	return ok;
}

/* Called from receive_Data.
 * Synchronize packets on sock with packets on msock.
 *
 * This is here so even when a P_DATA packet traveling via sock overtook an Ack
 * packet traveling on msock, they are still processed in the order they have
 * been sent.
 *
 * Note: we don't care for Ack packets overtaking P_DATA packets.
 *
 * In case packet_seq is larger than mdev->peer_seq number, there are
 * outstanding packets on the msock. We wait for them to arrive.
 * In case we are the logically next packet, we update mdev->peer_seq
 * ourselves. Correctly handles 32bit wrap around.
 *
 * Assume we have a 10 GBit connection, that is about 1<<30 byte per second,
 * about 1<<21 sectors per second. So "worst" case, we have 1<<3 == 8 seconds
 * for the 24bit wrap (historical atomic_t guarantee on some archs), and we have
 * 1<<9 == 512 seconds aka ages for the 32bit wrap around...
 *
 * returns 0 if we may process the packet,
 * -ERESTARTSYS if we were interrupted (by disconnect signal). */
static int drbd_wait_peer_seq(struct drbd_conf *mdev, const u32 packet_seq)
{
	DEFINE_WAIT(wait);
	unsigned int p_seq;
	long timeout;
	int ret = 0;
	spin_lock(&mdev->peer_seq_lock);
	for (;;) {
		prepare_to_wait(&mdev->seq_wait, &wait, TASK_INTERRUPTIBLE);
		if (seq_le(packet_seq, mdev->peer_seq+1))
			break;
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}
		p_seq = mdev->peer_seq;
		spin_unlock(&mdev->peer_seq_lock);
		timeout = schedule_timeout(30*HZ);
		spin_lock(&mdev->peer_seq_lock);
		if (timeout == 0 && p_seq == mdev->peer_seq) {
			ret = -ETIMEDOUT;
			dev_err(DEV, "ASSERT FAILED waited 30 seconds for sequence update, forcing reconnect\n");
			break;
		}
	}
	finish_wait(&mdev->seq_wait, &wait);
	if (mdev->peer_seq+1 == packet_seq)
		mdev->peer_seq++;
	spin_unlock(&mdev->peer_seq_lock);
	return ret;
}

/* mirrored write */
static int receive_Data(struct drbd_conf *mdev, struct p_header *h)
{
	sector_t sector;
	struct drbd_epoch_entry *e;
	struct p_data *p = (struct p_data *)h;
	int header_size, data_size;
	int rw = WRITE;
	u32 dp_flags;

	header_size = sizeof(*p) - sizeof(*h);
	data_size   = h->length  - header_size;

	ERR_IF(data_size == 0) return FALSE;

	if (drbd_recv(mdev, h->payload, header_size) != header_size)
		return FALSE;

	if (!get_ldev(mdev)) {
		if (__ratelimit(&drbd_ratelimit_state))
			dev_err(DEV, "Can not write mirrored data block "
			    "to local disk.\n");
		spin_lock(&mdev->peer_seq_lock);
		if (mdev->peer_seq+1 == be32_to_cpu(p->seq_num))
			mdev->peer_seq++;
		spin_unlock(&mdev->peer_seq_lock);

		drbd_send_ack_dp(mdev, P_NEG_ACK, p);
		atomic_inc(&mdev->current_epoch->epoch_size);
		return drbd_drain_block(mdev, data_size);
	}

	/* get_ldev(mdev) successful.
	 * Corresponding put_ldev done either below (on various errors),
	 * or in drbd_endio_write_sec, if we successfully submit the data at
	 * the end of this function. */

	sector = be64_to_cpu(p->sector);
	e = read_in_block(mdev, p->block_id, sector, data_size);
	if (!e) {
		put_ldev(mdev);
		return FALSE;
	}

	e->private_bio->bi_end_io = drbd_endio_write_sec;
	e->w.cb = e_end_block;

	spin_lock(&mdev->epoch_lock);
	e->epoch = mdev->current_epoch;
	atomic_inc(&e->epoch->epoch_size);
	atomic_inc(&e->epoch->active);

	if (mdev->write_ordering == WO_bio_barrier && atomic_read(&e->epoch->epoch_size) == 1) {
		struct drbd_epoch *epoch;
		/* Issue a barrier if we start a new epoch, and the previous epoch
		   was not a epoch containing a single request which already was
		   a Barrier. */
		epoch = list_entry(e->epoch->list.prev, struct drbd_epoch, list);
		if (epoch == e->epoch) {
			set_bit(DE_CONTAINS_A_BARRIER, &e->epoch->flags);
			rw |= (1<<BIO_RW_BARRIER);
			e->flags |= EE_IS_BARRIER;
		} else {
			if (atomic_read(&epoch->epoch_size) > 1 ||
			    !test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags)) {
				set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags);
				set_bit(DE_CONTAINS_A_BARRIER, &e->epoch->flags);
				rw |= (1<<BIO_RW_BARRIER);
				e->flags |= EE_IS_BARRIER;
			}
		}
	}
	spin_unlock(&mdev->epoch_lock);

	dp_flags = be32_to_cpu(p->dp_flags);
	if (dp_flags & DP_HARDBARRIER) {
		dev_err(DEV, "ASSERT FAILED would have submitted barrier request\n");
		/* rw |= (1<<BIO_RW_BARRIER); */
	}
	if (dp_flags & DP_RW_SYNC)
		rw |= (1<<BIO_RW_SYNCIO) | (1<<BIO_RW_UNPLUG);
	if (dp_flags & DP_MAY_SET_IN_SYNC)
		e->flags |= EE_MAY_SET_IN_SYNC;

	/* I'm the receiver, I do hold a net_cnt reference. */
	if (!mdev->net_conf->two_primaries) {
		spin_lock_irq(&mdev->req_lock);
	} else {
		/* don't get the req_lock yet,
		 * we may sleep in drbd_wait_peer_seq */
		const int size = e->size;
		const int discard = test_bit(DISCARD_CONCURRENT, &mdev->flags);
		DEFINE_WAIT(wait);
		struct drbd_request *i;
		struct hlist_node *n;
		struct hlist_head *slot;
		int first;

		D_ASSERT(mdev->net_conf->wire_protocol == DRBD_PROT_C);
		BUG_ON(mdev->ee_hash == NULL);
		BUG_ON(mdev->tl_hash == NULL);

		/* conflict detection and handling:
		 * 1. wait on the sequence number,
		 *    in case this data packet overtook ACK packets.
		 * 2. check our hash tables for conflicting requests.
		 *    we only need to walk the tl_hash, since an ee can not
		 *    have a conflict with an other ee: on the submitting
		 *    node, the corresponding req had already been conflicting,
		 *    and a conflicting req is never sent.
		 *
		 * Note: for two_primaries, we are protocol C,
		 * so there cannot be any request that is DONE
		 * but still on the transfer log.
		 *
		 * unconditionally add to the ee_hash.
		 *
		 * if no conflicting request is found:
		 *    submit.
		 *
		 * if any conflicting request is found
		 * that has not yet been acked,
		 * AND I have the "discard concurrent writes" flag:
		 *	 queue (via done_ee) the P_DISCARD_ACK; OUT.
		 *
		 * if any conflicting request is found:
		 *	 block the receiver, waiting on misc_wait
		 *	 until no more conflicting requests are there,
		 *	 or we get interrupted (disconnect).
		 *
		 *	 we do not just write after local io completion of those
		 *	 requests, but only after req is done completely, i.e.
		 *	 we wait for the P_DISCARD_ACK to arrive!
		 *
		 *	 then proceed normally, i.e. submit.
		 */
		if (drbd_wait_peer_seq(mdev, be32_to_cpu(p->seq_num)))
			goto out_interrupted;

		spin_lock_irq(&mdev->req_lock);

		hlist_add_head(&e->colision, ee_hash_slot(mdev, sector));

#define OVERLAPS overlaps(i->sector, i->size, sector, size)
		slot = tl_hash_slot(mdev, sector);
		first = 1;
		for (;;) {
			int have_unacked = 0;
			int have_conflict = 0;
			prepare_to_wait(&mdev->misc_wait, &wait,
				TASK_INTERRUPTIBLE);
			hlist_for_each_entry(i, n, slot, colision) {
				if (OVERLAPS) {
					/* only ALERT on first iteration,
					 * we may be woken up early... */
					if (first)
						dev_alert(DEV, "%s[%u] Concurrent local write detected!"
						      "	new: %llus +%u; pending: %llus +%u\n",
						      current->comm, current->pid,
						      (unsigned long long)sector, size,
						      (unsigned long long)i->sector, i->size);
					if (i->rq_state & RQ_NET_PENDING)
						++have_unacked;
					++have_conflict;
				}
			}
#undef OVERLAPS
			if (!have_conflict)
				break;

			/* Discard Ack only for the _first_ iteration */
			if (first && discard && have_unacked) {
				dev_alert(DEV, "Concurrent write! [DISCARD BY FLAG] sec=%llus\n",
				     (unsigned long long)sector);
				inc_unacked(mdev);
				e->w.cb = e_send_discard_ack;
				list_add_tail(&e->w.list, &mdev->done_ee);

				spin_unlock_irq(&mdev->req_lock);

				/* we could probably send that P_DISCARD_ACK ourselves,
				 * but I don't like the receiver using the msock */

				put_ldev(mdev);
				wake_asender(mdev);
				finish_wait(&mdev->misc_wait, &wait);
				return TRUE;
			}

			if (signal_pending(current)) {
				hlist_del_init(&e->colision);

				spin_unlock_irq(&mdev->req_lock);

				finish_wait(&mdev->misc_wait, &wait);
				goto out_interrupted;
			}

			spin_unlock_irq(&mdev->req_lock);
			if (first) {
				first = 0;
				dev_alert(DEV, "Concurrent write! [W AFTERWARDS] "
				     "sec=%llus\n", (unsigned long long)sector);
			} else if (discard) {
				/* we had none on the first iteration.
				 * there must be none now. */
				D_ASSERT(have_unacked == 0);
			}
			schedule();
			spin_lock_irq(&mdev->req_lock);
		}
		finish_wait(&mdev->misc_wait, &wait);
	}

	list_add(&e->w.list, &mdev->active_ee);
	spin_unlock_irq(&mdev->req_lock);

	switch (mdev->net_conf->wire_protocol) {
	case DRBD_PROT_C:
		inc_unacked(mdev);
		/* corresponding dec_unacked() in e_end_block()
		 * respective _drbd_clear_done_ee */
		break;
	case DRBD_PROT_B:
		/* I really don't like it that the receiver thread
		 * sends on the msock, but anyways */
		drbd_send_ack(mdev, P_RECV_ACK, e);
		break;
	case DRBD_PROT_A:
		/* nothing to do */
		break;
	}

	if (mdev->state.pdsk == D_DISKLESS) {
		/* In case we have the only disk of the cluster, */
		drbd_set_out_of_sync(mdev, e->sector, e->size);
		e->flags |= EE_CALL_AL_COMPLETE_IO;
		drbd_al_begin_io(mdev, e->sector);
	}

	e->private_bio->bi_rw = rw;
	drbd_generic_make_request(mdev, DRBD_FAULT_DT_WR, e->private_bio);
	/* accounting done in endio */

	maybe_kick_lo(mdev);
	return TRUE;

out_interrupted:
	/* yes, the epoch_size now is imbalanced.
	 * but we drop the connection anyways, so we don't have a chance to
	 * receive a barrier... atomic_inc(&mdev->epoch_size); */
	put_ldev(mdev);
	drbd_free_ee(mdev, e);
	return FALSE;
}

static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
{
	sector_t sector;
	const sector_t capacity = drbd_get_capacity(mdev->this_bdev);
	struct drbd_epoch_entry *e;
	struct digest_info *di = NULL;
	int size, digest_size;
	unsigned int fault_type;
	struct p_block_req *p =
		(struct p_block_req *)h;
	const int brps = sizeof(*p)-sizeof(*h);

	if (drbd_recv(mdev, h->payload, brps) != brps)
		return FALSE;

	sector = be64_to_cpu(p->sector);
	size   = be32_to_cpu(p->blksize);

	if (size <= 0 || (size & 0x1ff) != 0 || size > DRBD_MAX_SEGMENT_SIZE) {
		dev_err(DEV, "%s:%d: sector: %llus, size: %u\n", __FILE__, __LINE__,
				(unsigned long long)sector, size);
		return FALSE;
	}
	if (sector + (size>>9) > capacity) {
		dev_err(DEV, "%s:%d: sector: %llus, size: %u\n", __FILE__, __LINE__,
				(unsigned long long)sector, size);
		return FALSE;
	}

	if (!get_ldev_if_state(mdev, D_UP_TO_DATE)) {
		if (__ratelimit(&drbd_ratelimit_state))
			dev_err(DEV, "Can not satisfy peer's read request, "
			    "no local data.\n");
		drbd_send_ack_rp(mdev, h->command == P_DATA_REQUEST ? P_NEG_DREPLY :
				 P_NEG_RS_DREPLY , p);
		return TRUE;
	}

	/* GFP_NOIO, because we must not cause arbitrary write-out: in a DRBD
	 * "criss-cross" setup, that might cause write-out on some other DRBD,
	 * which in turn might block on the other node at this very place.  */
	e = drbd_alloc_ee(mdev, p->block_id, sector, size, GFP_NOIO);
	if (!e) {
		put_ldev(mdev);
		return FALSE;
	}

	e->private_bio->bi_rw = READ;
	e->private_bio->bi_end_io = drbd_endio_read_sec;

	switch (h->command) {
	case P_DATA_REQUEST:
		e->w.cb = w_e_end_data_req;
		fault_type = DRBD_FAULT_DT_RD;
		break;
	case P_RS_DATA_REQUEST:
		e->w.cb = w_e_end_rsdata_req;
		fault_type = DRBD_FAULT_RS_RD;
		/* Eventually this should become asynchronously. Currently it
		 * blocks the whole receiver just to delay the reading of a
		 * resync data block.
		 * the drbd_work_queue mechanism is made for this...
		 */
		if (!drbd_rs_begin_io(mdev, sector)) {
			/* we have been interrupted,
			 * probably connection lost! */
			D_ASSERT(signal_pending(current));
			goto out_free_e;
		}
		break;

	case P_OV_REPLY:
	case P_CSUM_RS_REQUEST:
		fault_type = DRBD_FAULT_RS_RD;
		digest_size = h->length - brps ;
		di = kmalloc(sizeof(*di) + digest_size, GFP_NOIO);
		if (!di)
			goto out_free_e;

		di->digest_size = digest_size;
		di->digest = (((char *)di)+sizeof(struct digest_info));

		if (drbd_recv(mdev, di->digest, digest_size) != digest_size)
			goto out_free_e;

		e->block_id = (u64)(unsigned long)di;
		if (h->command == P_CSUM_RS_REQUEST) {
			D_ASSERT(mdev->agreed_pro_version >= 89);
			e->w.cb = w_e_end_csum_rs_req;
		} else if (h->command == P_OV_REPLY) {
			e->w.cb = w_e_end_ov_reply;
			dec_rs_pending(mdev);
			break;
		}

		if (!drbd_rs_begin_io(mdev, sector)) {
			/* we have been interrupted, probably connection lost! */
			D_ASSERT(signal_pending(current));
			goto out_free_e;
		}
		break;

	case P_OV_REQUEST:
		if (mdev->state.conn >= C_CONNECTED &&
		    mdev->state.conn != C_VERIFY_T)
			dev_warn(DEV, "ASSERT FAILED: got P_OV_REQUEST while being %s\n",
				drbd_conn_str(mdev->state.conn));
		if (mdev->ov_start_sector == ~(sector_t)0 &&
		    mdev->agreed_pro_version >= 90) {
			mdev->ov_start_sector = sector;
			mdev->ov_position = sector;
			mdev->ov_left = mdev->rs_total - BM_SECT_TO_BIT(sector);
			dev_info(DEV, "Online Verify start sector: %llu\n",
					(unsigned long long)sector);
		}
		e->w.cb = w_e_end_ov_req;
		fault_type = DRBD_FAULT_RS_RD;
		/* Eventually this should become asynchronous. Currently it
		 * blocks the whole receiver just to delay the reading of a
		 * resync data block.
		 * the drbd_work_queue mechanism is made for this...
		 */
		if (!drbd_rs_begin_io(mdev, sector)) {
			/* we have been interrupted,
			 * probably connection lost! */
			D_ASSERT(signal_pending(current));
			goto out_free_e;
		}
		break;


	default:
		dev_err(DEV, "unexpected command (%s) in receive_DataRequest\n",
		    cmdname(h->command));
		fault_type = DRBD_FAULT_MAX;
	}

	spin_lock_irq(&mdev->req_lock);
	list_add(&e->w.list, &mdev->read_ee);
	spin_unlock_irq(&mdev->req_lock);

	inc_unacked(mdev);

	drbd_generic_make_request(mdev, fault_type, e->private_bio);
	maybe_kick_lo(mdev);

	return TRUE;

out_free_e:
	kfree(di);
	put_ldev(mdev);
	drbd_free_ee(mdev, e);
	return FALSE;
}

static int drbd_asb_recover_0p(struct drbd_conf *mdev) __must_hold(local)
{
	int self, peer, rv = -100;
	unsigned long ch_self, ch_peer;

	self = mdev->ldev->md.uuid[UI_BITMAP] & 1;
	peer = mdev->p_uuid[UI_BITMAP] & 1;

	ch_peer = mdev->p_uuid[UI_SIZE];
	ch_self = mdev->comm_bm_set;

	switch (mdev->net_conf->after_sb_0p) {
	case ASB_CONSENSUS:
	case ASB_DISCARD_SECONDARY:
	case ASB_CALL_HELPER:
		dev_err(DEV, "Configuration error.\n");
		break;
	case ASB_DISCONNECT:
		break;
	case ASB_DISCARD_YOUNGER_PRI:
		if (self == 0 && peer == 1) {
			rv = -1;
			break;
		}
		if (self == 1 && peer == 0) {
			rv =  1;
			break;
		}
		/* Else fall through to one of the other strategies... */
	case ASB_DISCARD_OLDER_PRI:
		if (self == 0 && peer == 1) {
			rv = 1;
			break;
		}
		if (self == 1 && peer == 0) {
			rv = -1;
			break;
		}
		/* Else fall through to one of the other strategies... */
		dev_warn(DEV, "Discard younger/older primary did not find a decision\n"
		     "Using discard-least-changes instead\n");
	case ASB_DISCARD_ZERO_CHG:
		if (ch_peer == 0 && ch_self == 0) {
			rv = test_bit(DISCARD_CONCURRENT, &mdev->flags)
				? -1 : 1;
			break;
		} else {
			if (ch_peer == 0) { rv =  1; break; }
			if (ch_self == 0) { rv = -1; break; }
		}
		if (mdev->net_conf->after_sb_0p == ASB_DISCARD_ZERO_CHG)
			break;
	case ASB_DISCARD_LEAST_CHG:
		if	(ch_self < ch_peer)
			rv = -1;
		else if (ch_self > ch_peer)
			rv =  1;
		else /* ( ch_self == ch_peer ) */
		     /* Well, then use something else. */
			rv = test_bit(DISCARD_CONCURRENT, &mdev->flags)
				? -1 : 1;
		break;
	case ASB_DISCARD_LOCAL:
		rv = -1;
		break;
	case ASB_DISCARD_REMOTE:
		rv =  1;
	}

	return rv;
}

static int drbd_asb_recover_1p(struct drbd_conf *mdev) __must_hold(local)
{
	int self, peer, hg, rv = -100;

	self = mdev->ldev->md.uuid[UI_BITMAP] & 1;
	peer = mdev->p_uuid[UI_BITMAP] & 1;

	switch (mdev->net_conf->after_sb_1p) {
	case ASB_DISCARD_YOUNGER_PRI:
	case ASB_DISCARD_OLDER_PRI:
	case ASB_DISCARD_LEAST_CHG:
	case ASB_DISCARD_LOCAL:
	case ASB_DISCARD_REMOTE:
		dev_err(DEV, "Configuration error.\n");
		break;
	case ASB_DISCONNECT:
		break;
	case ASB_CONSENSUS:
		hg = drbd_asb_recover_0p(mdev);
		if (hg == -1 && mdev->state.role == R_SECONDARY)
			rv = hg;
		if (hg == 1  && mdev->state.role == R_PRIMARY)
			rv = hg;
		break;
	case ASB_VIOLENTLY:
		rv = drbd_asb_recover_0p(mdev);
		break;
	case ASB_DISCARD_SECONDARY:
		return mdev->state.role == R_PRIMARY ? 1 : -1;
	case ASB_CALL_HELPER:
		hg = drbd_asb_recover_0p(mdev);
		if (hg == -1 && mdev->state.role == R_PRIMARY) {
			self = drbd_set_role(mdev, R_SECONDARY, 0);
			 /* drbd_change_state() does not sleep while in SS_IN_TRANSIENT_STATE,
			  * we might be here in C_WF_REPORT_PARAMS which is transient.
			  * we do not need to wait for the after state change work either. */
			self = drbd_change_state(mdev, CS_VERBOSE, NS(role, R_SECONDARY));
			if (self != SS_SUCCESS) {
				drbd_khelper(mdev, "pri-lost-after-sb");
			} else {
				dev_warn(DEV, "Successfully gave up primary role.\n");
				rv = hg;
			}
		} else
			rv = hg;
	}

	return rv;
}

static int drbd_asb_recover_2p(struct drbd_conf *mdev) __must_hold(local)
{
	int self, peer, hg, rv = -100;

	self = mdev->ldev->md.uuid[UI_BITMAP] & 1;
	peer = mdev->p_uuid[UI_BITMAP] & 1;

	switch (mdev->net_conf->after_sb_2p) {
	case ASB_DISCARD_YOUNGER_PRI:
	case ASB_DISCARD_OLDER_PRI:
	case ASB_DISCARD_LEAST_CHG:
	case ASB_DISCARD_LOCAL:
	case ASB_DISCARD_REMOTE:
	case ASB_CONSENSUS:
	case ASB_DISCARD_SECONDARY:
		dev_err(DEV, "Configuration error.\n");
		break;
	case ASB_VIOLENTLY:
		rv = drbd_asb_recover_0p(mdev);
		break;
	case ASB_DISCONNECT:
		break;
	case ASB_CALL_HELPER:
		hg = drbd_asb_recover_0p(mdev);
		if (hg == -1) {
			 /* drbd_change_state() does not sleep while in SS_IN_TRANSIENT_STATE,
			  * we might be here in C_WF_REPORT_PARAMS which is transient.
			  * we do not need to wait for the after state change work either. */
			self = drbd_change_state(mdev, CS_VERBOSE, NS(role, R_SECONDARY));
			if (self != SS_SUCCESS) {
				drbd_khelper(mdev, "pri-lost-after-sb");
			} else {
				dev_warn(DEV, "Successfully gave up primary role.\n");
				rv = hg;
			}
		} else
			rv = hg;
	}

	return rv;
}

static void drbd_uuid_dump(struct drbd_conf *mdev, char *text, u64 *uuid,
			   u64 bits, u64 flags)
{
	if (!uuid) {
		dev_info(DEV, "%s uuid info vanished while I was looking!\n", text);
		return;
	}
	dev_info(DEV, "%s %016llX:%016llX:%016llX:%016llX bits:%llu flags:%llX\n",
	     text,
	     (unsigned long long)uuid[UI_CURRENT],
	     (unsigned long long)uuid[UI_BITMAP],
	     (unsigned long long)uuid[UI_HISTORY_START],
	     (unsigned long long)uuid[UI_HISTORY_END],
	     (unsigned long long)bits,
	     (unsigned long long)flags);
}

/*
  100	after split brain try auto recover
    2	C_SYNC_SOURCE set BitMap
    1	C_SYNC_SOURCE use BitMap
    0	no Sync
   -1	C_SYNC_TARGET use BitMap
   -2	C_SYNC_TARGET set BitMap
 -100	after split brain, disconnect
-1000	unrelated data
 */
static int drbd_uuid_compare(struct drbd_conf *mdev, int *rule_nr) __must_hold(local)
{
	u64 self, peer;
	int i, j;

	self = mdev->ldev->md.uuid[UI_CURRENT] & ~((u64)1);
	peer = mdev->p_uuid[UI_CURRENT] & ~((u64)1);

	*rule_nr = 10;
	if (self == UUID_JUST_CREATED && peer == UUID_JUST_CREATED)
		return 0;

	*rule_nr = 20;
	if ((self == UUID_JUST_CREATED || self == (u64)0) &&
	     peer != UUID_JUST_CREATED)
		return -2;

	*rule_nr = 30;
	if (self != UUID_JUST_CREATED &&
	    (peer == UUID_JUST_CREATED || peer == (u64)0))
		return 2;

	if (self == peer) {
		int rct, dc; /* roles at crash time */

		if (mdev->p_uuid[UI_BITMAP] == (u64)0 && mdev->ldev->md.uuid[UI_BITMAP] != (u64)0) {

			if (mdev->agreed_pro_version < 91)
				return -1001;

			if ((mdev->ldev->md.uuid[UI_BITMAP] & ~((u64)1)) == (mdev->p_uuid[UI_HISTORY_START] & ~((u64)1)) &&
			    (mdev->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) == (mdev->p_uuid[UI_HISTORY_START + 1] & ~((u64)1))) {
				dev_info(DEV, "was SyncSource, missed the resync finished event, corrected myself:\n");
				drbd_uuid_set_bm(mdev, 0UL);

				drbd_uuid_dump(mdev, "self", mdev->ldev->md.uuid,
					       mdev->state.disk >= D_NEGOTIATING ? drbd_bm_total_weight(mdev) : 0, 0);
				*rule_nr = 34;
			} else {
				dev_info(DEV, "was SyncSource (peer failed to write sync_uuid)\n");
				*rule_nr = 36;
			}

			return 1;
		}

		if (mdev->ldev->md.uuid[UI_BITMAP] == (u64)0 && mdev->p_uuid[UI_BITMAP] != (u64)0) {

			if (mdev->agreed_pro_version < 91)
				return -1001;

			if ((mdev->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) == (mdev->p_uuid[UI_BITMAP] & ~((u64)1)) &&
			    (mdev->ldev->md.uuid[UI_HISTORY_START + 1] & ~((u64)1)) == (mdev->p_uuid[UI_HISTORY_START] & ~((u64)1))) {
				dev_info(DEV, "was SyncTarget, peer missed the resync finished event, corrected peer:\n");

				mdev->p_uuid[UI_HISTORY_START + 1] = mdev->p_uuid[UI_HISTORY_START];
				mdev->p_uuid[UI_HISTORY_START] = mdev->p_uuid[UI_BITMAP];
				mdev->p_uuid[UI_BITMAP] = 0UL;

				drbd_uuid_dump(mdev, "peer", mdev->p_uuid, mdev->p_uuid[UI_SIZE], mdev->p_uuid[UI_FLAGS]);
				*rule_nr = 35;
			} else {
				dev_info(DEV, "was SyncTarget (failed to write sync_uuid)\n");
				*rule_nr = 37;
			}

			return -1;
		}

		/* Common power [off|failure] */
		rct = (test_bit(CRASHED_PRIMARY, &mdev->flags) ? 1 : 0) +
			(mdev->p_uuid[UI_FLAGS] & 2);
		/* lowest bit is set when we were primary,
		 * next bit (weight 2) is set when peer was primary */
		*rule_nr = 40;

		switch (rct) {
		case 0: /* !self_pri && !peer_pri */ return 0;
		case 1: /*  self_pri && !peer_pri */ return 1;
		case 2: /* !self_pri &&  peer_pri */ return -1;
		case 3: /*  self_pri &&  peer_pri */
			dc = test_bit(DISCARD_CONCURRENT, &mdev->flags);
			return dc ? -1 : 1;
		}
	}

	*rule_nr = 50;
	peer = mdev->p_uuid[UI_BITMAP] & ~((u64)1);
	if (self == peer)
		return -1;

	*rule_nr = 51;
	peer = mdev->p_uuid[UI_HISTORY_START] & ~((u64)1);
	if (self == peer) {
		self = mdev->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1);
		peer = mdev->p_uuid[UI_HISTORY_START + 1] & ~((u64)1);
		if (self == peer) {
			/* The last P_SYNC_UUID did not get though. Undo the last start of
			   resync as sync source modifications of the peer's UUIDs. */

			if (mdev->agreed_pro_version < 91)
				return -1001;

			mdev->p_uuid[UI_BITMAP] = mdev->p_uuid[UI_HISTORY_START];
			mdev->p_uuid[UI_HISTORY_START] = mdev->p_uuid[UI_HISTORY_START + 1];
			return -1;
		}
	}

	*rule_nr = 60;
	self = mdev->ldev->md.uuid[UI_CURRENT] & ~((u64)1);
	for (i = UI_HISTORY_START; i <= UI_HISTORY_END; i++) {
		peer = mdev->p_uuid[i] & ~((u64)1);
		if (self == peer)
			return -2;
	}

	*rule_nr = 70;
	self = mdev->ldev->md.uuid[UI_BITMAP] & ~((u64)1);
	peer = mdev->p_uuid[UI_CURRENT] & ~((u64)1);
	if (self == peer)
		return 1;

	*rule_nr = 71;
	self = mdev->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1);
	if (self == peer) {
		self = mdev->ldev->md.uuid[UI_HISTORY_START + 1] & ~((u64)1);
		peer = mdev->p_uuid[UI_HISTORY_START] & ~((u64)1);
		if (self == peer) {
			/* The last P_SYNC_UUID did not get though. Undo the last start of
			   resync as sync source modifications of our UUIDs. */

			if (mdev->agreed_pro_version < 91)
				return -1001;

			_drbd_uuid_set(mdev, UI_BITMAP, mdev->ldev->md.uuid[UI_HISTORY_START]);
			_drbd_uuid_set(mdev, UI_HISTORY_START, mdev->ldev->md.uuid[UI_HISTORY_START + 1]);

			dev_info(DEV, "Undid last start of resync:\n");

			drbd_uuid_dump(mdev, "self", mdev->ldev->md.uuid,
				       mdev->state.disk >= D_NEGOTIATING ? drbd_bm_total_weight(mdev) : 0, 0);

			return 1;
		}
	}


	*rule_nr = 80;
	peer = mdev->p_uuid[UI_CURRENT] & ~((u64)1);
	for (i = UI_HISTORY_START; i <= UI_HISTORY_END; i++) {
		self = mdev->ldev->md.uuid[i] & ~((u64)1);
		if (self == peer)
			return 2;
	}

	*rule_nr = 90;
	self = mdev->ldev->md.uuid[UI_BITMAP] & ~((u64)1);
	peer = mdev->p_uuid[UI_BITMAP] & ~((u64)1);
	if (self == peer && self != ((u64)0))
		return 100;

	*rule_nr = 100;
	for (i = UI_HISTORY_START; i <= UI_HISTORY_END; i++) {
		self = mdev->ldev->md.uuid[i] & ~((u64)1);
		for (j = UI_HISTORY_START; j <= UI_HISTORY_END; j++) {
			peer = mdev->p_uuid[j] & ~((u64)1);
			if (self == peer)
				return -100;
		}
	}

	return -1000;
}

/* drbd_sync_handshake() returns the new conn state on success, or
   CONN_MASK (-1) on failure.
 */
static enum drbd_conns drbd_sync_handshake(struct drbd_conf *mdev, enum drbd_role peer_role,
					   enum drbd_disk_state peer_disk) __must_hold(local)
{
	int hg, rule_nr;
	enum drbd_conns rv = C_MASK;
	enum drbd_disk_state mydisk;

	mydisk = mdev->state.disk;
	if (mydisk == D_NEGOTIATING)
		mydisk = mdev->new_state_tmp.disk;

	dev_info(DEV, "drbd_sync_handshake:\n");
	drbd_uuid_dump(mdev, "self", mdev->ldev->md.uuid, mdev->comm_bm_set, 0);
	drbd_uuid_dump(mdev, "peer", mdev->p_uuid,
		       mdev->p_uuid[UI_SIZE], mdev->p_uuid[UI_FLAGS]);

	hg = drbd_uuid_compare(mdev, &rule_nr);

	dev_info(DEV, "uuid_compare()=%d by rule %d\n", hg, rule_nr);

	if (hg == -1000) {
		dev_alert(DEV, "Unrelated data, aborting!\n");
		return C_MASK;
	}
	if (hg == -1001) {
		dev_alert(DEV, "To resolve this both sides have to support at least protocol\n");
		return C_MASK;
	}

	if    ((mydisk == D_INCONSISTENT && peer_disk > D_INCONSISTENT) ||
	    (peer_disk == D_INCONSISTENT && mydisk    > D_INCONSISTENT)) {
		int f = (hg == -100) || abs(hg) == 2;
		hg = mydisk > D_INCONSISTENT ? 1 : -1;
		if (f)
			hg = hg*2;
		dev_info(DEV, "Becoming sync %s due to disk states.\n",
		     hg > 0 ? "source" : "target");
	}

	if (hg == 100 || (hg == -100 && mdev->net_conf->always_asbp)) {
		int pcount = (mdev->state.role == R_PRIMARY)
			   + (peer_role == R_PRIMARY);
		int forced = (hg == -100);

		switch (pcount) {
		case 0:
			hg = drbd_asb_recover_0p(mdev);
			break;
		case 1:
			hg = drbd_asb_recover_1p(mdev);
			break;
		case 2:
			hg = drbd_asb_recover_2p(mdev);
			break;
		}
		if (abs(hg) < 100) {
			dev_warn(DEV, "Split-Brain detected, %d primaries, "
			     "automatically solved. Sync from %s node\n",
			     pcount, (hg < 0) ? "peer" : "this");
			if (forced) {
				dev_warn(DEV, "Doing a full sync, since"
				     " UUIDs where ambiguous.\n");
				hg = hg*2;
			}
		}
	}

	if (hg == -100) {
		if (mdev->net_conf->want_lose && !(mdev->p_uuid[UI_FLAGS]&1))
			hg = -1;
		if (!mdev->net_conf->want_lose && (mdev->p_uuid[UI_FLAGS]&1))
			hg = 1;

		if (abs(hg) < 100)
			dev_warn(DEV, "Split-Brain detected, manually solved. "
			     "Sync from %s node\n",
			     (hg < 0) ? "peer" : "this");
	}

	if (hg == -100) {
		/* FIXME this log message is not correct if we end up here
		 * after an attempted attach on a diskless node.
		 * We just refuse to attach -- well, we drop the "connection"
		 * to that disk, in a way... */
		dev_alert(DEV, "Split-Brain detected, dropping connection!\n");
		drbd_khelper(mdev, "split-brain");
		return C_MASK;
	}

	if (hg > 0 && mydisk <= D_INCONSISTENT) {
		dev_err(DEV, "I shall become SyncSource, but I am inconsistent!\n");
		return C_MASK;
	}

	if (hg < 0 && /* by intention we do not use mydisk here. */
	    mdev->state.role == R_PRIMARY && mdev->state.disk >= D_CONSISTENT) {
		switch (mdev->net_conf->rr_conflict) {
		case ASB_CALL_HELPER:
			drbd_khelper(mdev, "pri-lost");
			/* fall through */
		case ASB_DISCONNECT:
			dev_err(DEV, "I shall become SyncTarget, but I am primary!\n");
			return C_MASK;
		case ASB_VIOLENTLY:
			dev_warn(DEV, "Becoming SyncTarget, violating the stable-data"
			     "assumption\n");
		}
	}

	if (mdev->net_conf->dry_run || test_bit(CONN_DRY_RUN, &mdev->flags)) {
		if (hg == 0)
			dev_info(DEV, "dry-run connect: No resync, would become Connected immediately.\n");
		else
			dev_info(DEV, "dry-run connect: Would become %s, doing a %s resync.",
				 drbd_conn_str(hg > 0 ? C_SYNC_SOURCE : C_SYNC_TARGET),
				 abs(hg) >= 2 ? "full" : "bit-map based");
		return C_MASK;
	}

	if (abs(hg) >= 2) {
		dev_info(DEV, "Writing the whole bitmap, full sync required after drbd_sync_handshake.\n");
		if (drbd_bitmap_io(mdev, &drbd_bmio_set_n_write, "set_n_write from sync_handshake"))
			return C_MASK;
	}

	if (hg > 0) { /* become sync source. */
		rv = C_WF_BITMAP_S;
	} else if (hg < 0) { /* become sync target */
		rv = C_WF_BITMAP_T;
	} else {
		rv = C_CONNECTED;
		if (drbd_bm_total_weight(mdev)) {
			dev_info(DEV, "No resync, but %lu bits in bitmap!\n",
			     drbd_bm_total_weight(mdev));
		}
	}

	return rv;
}

/* returns 1 if invalid */
static int cmp_after_sb(enum drbd_after_sb_p peer, enum drbd_after_sb_p self)
{
	/* ASB_DISCARD_REMOTE - ASB_DISCARD_LOCAL is valid */
	if ((peer == ASB_DISCARD_REMOTE && self == ASB_DISCARD_LOCAL) ||
	    (self == ASB_DISCARD_REMOTE && peer == ASB_DISCARD_LOCAL))
		return 0;

	/* any other things with ASB_DISCARD_REMOTE or ASB_DISCARD_LOCAL are invalid */
	if (peer == ASB_DISCARD_REMOTE || peer == ASB_DISCARD_LOCAL ||
	    self == ASB_DISCARD_REMOTE || self == ASB_DISCARD_LOCAL)
		return 1;

	/* everything else is valid if they are equal on both sides. */
	if (peer == self)
		return 0;

	/* everything es is invalid. */
	return 1;
}

static int receive_protocol(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_protocol *p = (struct p_protocol *)h;
	int header_size, data_size;
	int p_proto, p_after_sb_0p, p_after_sb_1p, p_after_sb_2p;
	int p_want_lose, p_two_primaries, cf;
	char p_integrity_alg[SHARED_SECRET_MAX] = "";

	header_size = sizeof(*p) - sizeof(*h);
	data_size   = h->length  - header_size;

	if (drbd_recv(mdev, h->payload, header_size) != header_size)
		return FALSE;

	p_proto		= be32_to_cpu(p->protocol);
	p_after_sb_0p	= be32_to_cpu(p->after_sb_0p);
	p_after_sb_1p	= be32_to_cpu(p->after_sb_1p);
	p_after_sb_2p	= be32_to_cpu(p->after_sb_2p);
	p_two_primaries = be32_to_cpu(p->two_primaries);
	cf		= be32_to_cpu(p->conn_flags);
	p_want_lose = cf & CF_WANT_LOSE;

	clear_bit(CONN_DRY_RUN, &mdev->flags);

	if (cf & CF_DRY_RUN)
		set_bit(CONN_DRY_RUN, &mdev->flags);

	if (p_proto != mdev->net_conf->wire_protocol) {
		dev_err(DEV, "incompatible communication protocols\n");
		goto disconnect;
	}

	if (cmp_after_sb(p_after_sb_0p, mdev->net_conf->after_sb_0p)) {
		dev_err(DEV, "incompatible after-sb-0pri settings\n");
		goto disconnect;
	}

	if (cmp_after_sb(p_after_sb_1p, mdev->net_conf->after_sb_1p)) {
		dev_err(DEV, "incompatible after-sb-1pri settings\n");
		goto disconnect;
	}

	if (cmp_after_sb(p_after_sb_2p, mdev->net_conf->after_sb_2p)) {
		dev_err(DEV, "incompatible after-sb-2pri settings\n");
		goto disconnect;
	}

	if (p_want_lose && mdev->net_conf->want_lose) {
		dev_err(DEV, "both sides have the 'want_lose' flag set\n");
		goto disconnect;
	}

	if (p_two_primaries != mdev->net_conf->two_primaries) {
		dev_err(DEV, "incompatible setting of the two-primaries options\n");
		goto disconnect;
	}

	if (mdev->agreed_pro_version >= 87) {
		unsigned char *my_alg = mdev->net_conf->integrity_alg;

		if (drbd_recv(mdev, p_integrity_alg, data_size) != data_size)
			return FALSE;

		p_integrity_alg[SHARED_SECRET_MAX-1] = 0;
		if (strcmp(p_integrity_alg, my_alg)) {
			dev_err(DEV, "incompatible setting of the data-integrity-alg\n");
			goto disconnect;
		}
		dev_info(DEV, "data-integrity-alg: %s\n",
		     my_alg[0] ? my_alg : (unsigned char *)"<not-used>");
	}

	return TRUE;

disconnect:
	drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
	return FALSE;
}

/* helper function
 * input: alg name, feature name
 * return: NULL (alg name was "")
 *         ERR_PTR(error) if something goes wrong
 *         or the crypto hash ptr, if it worked out ok. */
struct crypto_hash *drbd_crypto_alloc_digest_safe(const struct drbd_conf *mdev,
		const char *alg, const char *name)
{
	struct crypto_hash *tfm;

	if (!alg[0])
		return NULL;

	tfm = crypto_alloc_hash(alg, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(tfm)) {
		dev_err(DEV, "Can not allocate \"%s\" as %s (reason: %ld)\n",
			alg, name, PTR_ERR(tfm));
		return tfm;
	}
	if (!drbd_crypto_is_hash(crypto_hash_tfm(tfm))) {
		crypto_free_hash(tfm);
		dev_err(DEV, "\"%s\" is not a digest (%s)\n", alg, name);
		return ERR_PTR(-EINVAL);
	}
	return tfm;
}

static int receive_SyncParam(struct drbd_conf *mdev, struct p_header *h)
{
	int ok = TRUE;
	struct p_rs_param_89 *p = (struct p_rs_param_89 *)h;
	unsigned int header_size, data_size, exp_max_sz;
	struct crypto_hash *verify_tfm = NULL;
	struct crypto_hash *csums_tfm = NULL;
	const int apv = mdev->agreed_pro_version;

	exp_max_sz  = apv <= 87 ? sizeof(struct p_rs_param)
		    : apv == 88 ? sizeof(struct p_rs_param)
					+ SHARED_SECRET_MAX
		    : /* 89 */    sizeof(struct p_rs_param_89);

	if (h->length > exp_max_sz) {
		dev_err(DEV, "SyncParam packet too long: received %u, expected <= %u bytes\n",
		    h->length, exp_max_sz);
		return FALSE;
	}

	if (apv <= 88) {
		header_size = sizeof(struct p_rs_param) - sizeof(*h);
		data_size   = h->length  - header_size;
	} else /* apv >= 89 */ {
		header_size = sizeof(struct p_rs_param_89) - sizeof(*h);
		data_size   = h->length  - header_size;
		D_ASSERT(data_size == 0);
	}

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

	if (drbd_recv(mdev, h->payload, header_size) != header_size)
		return FALSE;

	mdev->sync_conf.rate	  = be32_to_cpu(p->rate);

	if (apv >= 88) {
		if (apv == 88) {
			if (data_size > SHARED_SECRET_MAX) {
				dev_err(DEV, "verify-alg too long, "
				    "peer wants %u, accepting only %u byte\n",
						data_size, SHARED_SECRET_MAX);
				return FALSE;
			}

			if (drbd_recv(mdev, p->verify_alg, data_size) != data_size)
				return FALSE;

			/* we expect NUL terminated string */
			/* but just in case someone tries to be evil */
			D_ASSERT(p->verify_alg[data_size-1] == 0);
			p->verify_alg[data_size-1] = 0;

		} else /* apv >= 89 */ {
			/* we still expect NUL terminated strings */
			/* but just in case someone tries to be evil */
			D_ASSERT(p->verify_alg[SHARED_SECRET_MAX-1] == 0);
			D_ASSERT(p->csums_alg[SHARED_SECRET_MAX-1] == 0);
			p->verify_alg[SHARED_SECRET_MAX-1] = 0;
			p->csums_alg[SHARED_SECRET_MAX-1] = 0;
		}

		if (strcmp(mdev->sync_conf.verify_alg, p->verify_alg)) {
			if (mdev->state.conn == C_WF_REPORT_PARAMS) {
				dev_err(DEV, "Different verify-alg settings. me=\"%s\" peer=\"%s\"\n",
				    mdev->sync_conf.verify_alg, p->verify_alg);
				goto disconnect;
			}
			verify_tfm = drbd_crypto_alloc_digest_safe(mdev,
					p->verify_alg, "verify-alg");
			if (IS_ERR(verify_tfm)) {
				verify_tfm = NULL;
				goto disconnect;
			}
		}

		if (apv >= 89 && strcmp(mdev->sync_conf.csums_alg, p->csums_alg)) {
			if (mdev->state.conn == C_WF_REPORT_PARAMS) {
				dev_err(DEV, "Different csums-alg settings. me=\"%s\" peer=\"%s\"\n",
				    mdev->sync_conf.csums_alg, p->csums_alg);
				goto disconnect;
			}
			csums_tfm = drbd_crypto_alloc_digest_safe(mdev,
					p->csums_alg, "csums-alg");
			if (IS_ERR(csums_tfm)) {
				csums_tfm = NULL;
				goto disconnect;
			}
		}


		spin_lock(&mdev->peer_seq_lock);
		/* lock against drbd_nl_syncer_conf() */
		if (verify_tfm) {
			strcpy(mdev->sync_conf.verify_alg, p->verify_alg);
			mdev->sync_conf.verify_alg_len = strlen(p->verify_alg) + 1;
			crypto_free_hash(mdev->verify_tfm);
			mdev->verify_tfm = verify_tfm;
			dev_info(DEV, "using verify-alg: \"%s\"\n", p->verify_alg);
		}
		if (csums_tfm) {
			strcpy(mdev->sync_conf.csums_alg, p->csums_alg);
			mdev->sync_conf.csums_alg_len = strlen(p->csums_alg) + 1;
			crypto_free_hash(mdev->csums_tfm);
			mdev->csums_tfm = csums_tfm;
			dev_info(DEV, "using csums-alg: \"%s\"\n", p->csums_alg);
		}
		spin_unlock(&mdev->peer_seq_lock);
	}

	return ok;
disconnect:
	/* just for completeness: actually not needed,
	 * as this is not reached if csums_tfm was ok. */
	crypto_free_hash(csums_tfm);
	/* but free the verify_tfm again, if csums_tfm did not work out */
	crypto_free_hash(verify_tfm);
	drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
	return FALSE;
}

static void drbd_setup_order_type(struct drbd_conf *mdev, int peer)
{
	/* sorry, we currently have no working implementation
	 * of distributed TCQ */
}

/* warn if the arguments differ by more than 12.5% */
static void warn_if_differ_considerably(struct drbd_conf *mdev,
	const char *s, sector_t a, sector_t b)
{
	sector_t d;
	if (a == 0 || b == 0)
		return;
	d = (a > b) ? (a - b) : (b - a);
	if (d > (a>>3) || d > (b>>3))
		dev_warn(DEV, "Considerable difference in %s: %llus vs. %llus\n", s,
		     (unsigned long long)a, (unsigned long long)b);
}

static int receive_sizes(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_sizes *p = (struct p_sizes *)h;
	enum determine_dev_size dd = unchanged;
	unsigned int max_seg_s;
	sector_t p_size, p_usize, my_usize;
	int ldsc = 0; /* local disk size changed */
	enum drbd_conns nconn;

	ERR_IF(h->length != (sizeof(*p)-sizeof(*h))) return FALSE;
	if (drbd_recv(mdev, h->payload, h->length) != h->length)
		return FALSE;

	p_size = be64_to_cpu(p->d_size);
	p_usize = be64_to_cpu(p->u_size);

	if (p_size == 0 && mdev->state.disk == D_DISKLESS) {
		dev_err(DEV, "some backing storage is needed\n");
		drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
		return FALSE;
	}

	/* just store the peer's disk size for now.
	 * we still need to figure out whether we accept that. */
	mdev->p_size = p_size;

#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
	if (get_ldev(mdev)) {
		warn_if_differ_considerably(mdev, "lower level device sizes",
			   p_size, drbd_get_max_capacity(mdev->ldev));
		warn_if_differ_considerably(mdev, "user requested size",
					    p_usize, mdev->ldev->dc.disk_size);

		/* if this is the first connect, or an otherwise expected
		 * param exchange, choose the minimum */
		if (mdev->state.conn == C_WF_REPORT_PARAMS)
			p_usize = min_not_zero((sector_t)mdev->ldev->dc.disk_size,
					     p_usize);

		my_usize = mdev->ldev->dc.disk_size;

		if (mdev->ldev->dc.disk_size != p_usize) {
			mdev->ldev->dc.disk_size = p_usize;
			dev_info(DEV, "Peer sets u_size to %lu sectors\n",
			     (unsigned long)mdev->ldev->dc.disk_size);
		}

		/* Never shrink a device with usable data during connect.
		   But allow online shrinking if we are connected. */
		if (drbd_new_dev_size(mdev, mdev->ldev, 0) <
		   drbd_get_capacity(mdev->this_bdev) &&
		   mdev->state.disk >= D_OUTDATED &&
		   mdev->state.conn < C_CONNECTED) {
			dev_err(DEV, "The peer's disk size is too small!\n");
			drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
			mdev->ldev->dc.disk_size = my_usize;
			put_ldev(mdev);
			return FALSE;
		}
		put_ldev(mdev);
	}
#undef min_not_zero

	if (get_ldev(mdev)) {
	  dd = drbd_determin_dev_size(mdev, 0);
		put_ldev(mdev);
		if (dd == dev_size_error)
			return FALSE;
		drbd_md_sync(mdev);
	} else {
		/* I am diskless, need to accept the peer's size. */
		drbd_set_my_capacity(mdev, p_size);
	}

	if (mdev->p_uuid && mdev->state.conn <= C_CONNECTED && get_ldev(mdev)) {
		nconn = drbd_sync_handshake(mdev,
				mdev->state.peer, mdev->state.pdsk);
		put_ldev(mdev);

		if (nconn == C_MASK) {
			drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
			return FALSE;
		}

		if (drbd_request_state(mdev, NS(conn, nconn)) < SS_SUCCESS) {
			drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
			return FALSE;
		}
	}

	if (get_ldev(mdev)) {
		if (mdev->ldev->known_size != drbd_get_capacity(mdev->ldev->backing_bdev)) {
			mdev->ldev->known_size = drbd_get_capacity(mdev->ldev->backing_bdev);
			ldsc = 1;
		}

		max_seg_s = be32_to_cpu(p->max_segment_size);
		if (max_seg_s != queue_max_segment_size(mdev->rq_queue))
			drbd_setup_queue_param(mdev, max_seg_s);

		drbd_setup_order_type(mdev, be32_to_cpu(p->queue_order_type));
		put_ldev(mdev);
	}

	if (mdev->state.conn > C_WF_REPORT_PARAMS) {
		if (be64_to_cpu(p->c_size) !=
		    drbd_get_capacity(mdev->this_bdev) || ldsc) {
			/* we have different sizes, probably peer
			 * needs to know my new size... */
			drbd_send_sizes(mdev, 0);
		}
		if (test_and_clear_bit(RESIZE_PENDING, &mdev->flags) ||
		    (dd == grew && mdev->state.conn == C_CONNECTED)) {
			if (mdev->state.pdsk >= D_INCONSISTENT &&
			    mdev->state.disk >= D_INCONSISTENT)
				resync_after_online_grow(mdev);
			else
				set_bit(RESYNC_AFTER_NEG, &mdev->flags);
		}
	}

	return TRUE;
}

static int receive_uuids(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_uuids *p = (struct p_uuids *)h;
	u64 *p_uuid;
	int i;

	ERR_IF(h->length != (sizeof(*p)-sizeof(*h))) return FALSE;
	if (drbd_recv(mdev, h->payload, h->length) != h->length)
		return FALSE;

	p_uuid = kmalloc(sizeof(u64)*UI_EXTENDED_SIZE, GFP_NOIO);

	for (i = UI_CURRENT; i < UI_EXTENDED_SIZE; i++)
		p_uuid[i] = be64_to_cpu(p->uuid[i]);

	kfree(mdev->p_uuid);
	mdev->p_uuid = p_uuid;

	if (mdev->state.conn < C_CONNECTED &&
	    mdev->state.disk < D_INCONSISTENT &&
	    mdev->state.role == R_PRIMARY &&
	    (mdev->ed_uuid & ~((u64)1)) != (p_uuid[UI_CURRENT] & ~((u64)1))) {
		dev_err(DEV, "Can only connect to data with current UUID=%016llX\n",
		    (unsigned long long)mdev->ed_uuid);
		drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
		return FALSE;
	}

	if (get_ldev(mdev)) {
		int skip_initial_sync =
			mdev->state.conn == C_CONNECTED &&
			mdev->agreed_pro_version >= 90 &&
			mdev->ldev->md.uuid[UI_CURRENT] == UUID_JUST_CREATED &&
			(p_uuid[UI_FLAGS] & 8);
		if (skip_initial_sync) {
			dev_info(DEV, "Accepted new current UUID, preparing to skip initial sync\n");
			drbd_bitmap_io(mdev, &drbd_bmio_clear_n_write,
					"clear_n_write from receive_uuids");
			_drbd_uuid_set(mdev, UI_CURRENT, p_uuid[UI_CURRENT]);
			_drbd_uuid_set(mdev, UI_BITMAP, 0);
			_drbd_set_state(_NS2(mdev, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
					CS_VERBOSE, NULL);
			drbd_md_sync(mdev);
		}
		put_ldev(mdev);
	}

	/* Before we test for the disk state, we should wait until an eventually
	   ongoing cluster wide state change is finished. That is important if
	   we are primary and are detaching from our disk. We need to see the
	   new disk state... */
	wait_event(mdev->misc_wait, !test_bit(CLUSTER_ST_CHANGE, &mdev->flags));
	if (mdev->state.conn >= C_CONNECTED && mdev->state.disk < D_INCONSISTENT)
		drbd_set_ed_uuid(mdev, p_uuid[UI_CURRENT]);

	return TRUE;
}

/**
 * convert_state() - Converts the peer's view of the cluster state to our point of view
 * @ps:		The state as seen by the peer.
 */
static union drbd_state convert_state(union drbd_state ps)
{
	union drbd_state ms;

	static enum drbd_conns c_tab[] = {
		[C_CONNECTED] = C_CONNECTED,

		[C_STARTING_SYNC_S] = C_STARTING_SYNC_T,
		[C_STARTING_SYNC_T] = C_STARTING_SYNC_S,
		[C_DISCONNECTING] = C_TEAR_DOWN, /* C_NETWORK_FAILURE, */
		[C_VERIFY_S]       = C_VERIFY_T,
		[C_MASK]   = C_MASK,
	};

	ms.i = ps.i;

	ms.conn = c_tab[ps.conn];
	ms.peer = ps.role;
	ms.role = ps.peer;
	ms.pdsk = ps.disk;
	ms.disk = ps.pdsk;
	ms.peer_isp = (ps.aftr_isp | ps.user_isp);

	return ms;
}

static int receive_req_state(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_req_state *p = (struct p_req_state *)h;
	union drbd_state mask, val;
	int rv;

	ERR_IF(h->length != (sizeof(*p)-sizeof(*h))) return FALSE;
	if (drbd_recv(mdev, h->payload, h->length) != h->length)
		return FALSE;

	mask.i = be32_to_cpu(p->mask);
	val.i = be32_to_cpu(p->val);

	if (test_bit(DISCARD_CONCURRENT, &mdev->flags) &&
	    test_bit(CLUSTER_ST_CHANGE, &mdev->flags)) {
		drbd_send_sr_reply(mdev, SS_CONCURRENT_ST_CHG);
		return TRUE;
	}

	mask = convert_state(mask);
	val = convert_state(val);

	rv = drbd_change_state(mdev, CS_VERBOSE, mask, val);

	drbd_send_sr_reply(mdev, rv);
	drbd_md_sync(mdev);

	return TRUE;
}

static int receive_state(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_state *p = (struct p_state *)h;
	enum drbd_conns nconn, oconn;
	union drbd_state ns, peer_state;
	enum drbd_disk_state real_peer_disk;
	int rv;

	ERR_IF(h->length != (sizeof(*p)-sizeof(*h)))
		return FALSE;

	if (drbd_recv(mdev, h->payload, h->length) != h->length)
		return FALSE;

	peer_state.i = be32_to_cpu(p->state);

	real_peer_disk = peer_state.disk;
	if (peer_state.disk == D_NEGOTIATING) {
		real_peer_disk = mdev->p_uuid[UI_FLAGS] & 4 ? D_INCONSISTENT : D_CONSISTENT;
		dev_info(DEV, "real peer disk state = %s\n", drbd_disk_str(real_peer_disk));
	}

	spin_lock_irq(&mdev->req_lock);
 retry:
	oconn = nconn = mdev->state.conn;
	spin_unlock_irq(&mdev->req_lock);

	if (nconn == C_WF_REPORT_PARAMS)
		nconn = C_CONNECTED;

	if (mdev->p_uuid && peer_state.disk >= D_NEGOTIATING &&
	    get_ldev_if_state(mdev, D_NEGOTIATING)) {
		int cr; /* consider resync */

		/* if we established a new connection */
		cr  = (oconn < C_CONNECTED);
		/* if we had an established connection
		 * and one of the nodes newly attaches a disk */
		cr |= (oconn == C_CONNECTED &&
		       (peer_state.disk == D_NEGOTIATING ||
			mdev->state.disk == D_NEGOTIATING));
		/* if we have both been inconsistent, and the peer has been
		 * forced to be UpToDate with --overwrite-data */
		cr |= test_bit(CONSIDER_RESYNC, &mdev->flags);
		/* if we had been plain connected, and the admin requested to
		 * start a sync by "invalidate" or "invalidate-remote" */
		cr |= (oconn == C_CONNECTED &&
				(peer_state.conn >= C_STARTING_SYNC_S &&
				 peer_state.conn <= C_WF_BITMAP_T));

		if (cr)
			nconn = drbd_sync_handshake(mdev, peer_state.role, real_peer_disk);

		put_ldev(mdev);
		if (nconn == C_MASK) {
			nconn = C_CONNECTED;
			if (mdev->state.disk == D_NEGOTIATING) {
				drbd_force_state(mdev, NS(disk, D_DISKLESS));
			} else if (peer_state.disk == D_NEGOTIATING) {
				dev_err(DEV, "Disk attach process on the peer node was aborted.\n");
				peer_state.disk = D_DISKLESS;
				real_peer_disk = D_DISKLESS;
			} else {
				if (test_and_clear_bit(CONN_DRY_RUN, &mdev->flags))
					return FALSE;
				D_ASSERT(oconn == C_WF_REPORT_PARAMS);
				drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
				return FALSE;
			}
		}
	}

	spin_lock_irq(&mdev->req_lock);
	if (mdev->state.conn != oconn)
		goto retry;
	clear_bit(CONSIDER_RESYNC, &mdev->flags);
	ns.i = mdev->state.i;
	ns.conn = nconn;
	ns.peer = peer_state.role;
	ns.pdsk = real_peer_disk;
	ns.peer_isp = (peer_state.aftr_isp | peer_state.user_isp);
	if ((nconn == C_CONNECTED || nconn == C_WF_BITMAP_S) && ns.disk == D_NEGOTIATING)
		ns.disk = mdev->new_state_tmp.disk;

	rv = _drbd_set_state(mdev, ns, CS_VERBOSE | CS_HARD, NULL);
	ns = mdev->state;
	spin_unlock_irq(&mdev->req_lock);

	if (rv < SS_SUCCESS) {
		drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
		return FALSE;
	}

	if (oconn > C_WF_REPORT_PARAMS) {
		if (nconn > C_CONNECTED && peer_state.conn <= C_CONNECTED &&
		    peer_state.disk != D_NEGOTIATING ) {
			/* we want resync, peer has not yet decided to sync... */
			/* Nowadays only used when forcing a node into primary role and
			   setting its disk to UpToDate with that */
			drbd_send_uuids(mdev);
			drbd_send_state(mdev);
		}
	}

	mdev->net_conf->want_lose = 0;

	drbd_md_sync(mdev); /* update connected indicator, la_size, ... */

	return TRUE;
}

static int receive_sync_uuid(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_rs_uuid *p = (struct p_rs_uuid *)h;

	wait_event(mdev->misc_wait,
		   mdev->state.conn == C_WF_SYNC_UUID ||
		   mdev->state.conn < C_CONNECTED ||
		   mdev->state.disk < D_NEGOTIATING);

	/* D_ASSERT( mdev->state.conn == C_WF_SYNC_UUID ); */

	ERR_IF(h->length != (sizeof(*p)-sizeof(*h))) return FALSE;
	if (drbd_recv(mdev, h->payload, h->length) != h->length)
		return FALSE;

	/* Here the _drbd_uuid_ functions are right, current should
	   _not_ be rotated into the history */
	if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
		_drbd_uuid_set(mdev, UI_CURRENT, be64_to_cpu(p->uuid));
		_drbd_uuid_set(mdev, UI_BITMAP, 0UL);

		drbd_start_resync(mdev, C_SYNC_TARGET);

		put_ldev(mdev);
	} else
		dev_err(DEV, "Ignoring SyncUUID packet!\n");

	return TRUE;
}

enum receive_bitmap_ret { OK, DONE, FAILED };

static enum receive_bitmap_ret
receive_bitmap_plain(struct drbd_conf *mdev, struct p_header *h,
	unsigned long *buffer, struct bm_xfer_ctx *c)
{
	unsigned num_words = min_t(size_t, BM_PACKET_WORDS, c->bm_words - c->word_offset);
	unsigned want = num_words * sizeof(long);

	if (want != h->length) {
		dev_err(DEV, "%s:want (%u) != h->length (%u)\n", __func__, want, h->length);
		return FAILED;
	}
	if (want == 0)
		return DONE;
	if (drbd_recv(mdev, buffer, want) != want)
		return FAILED;

	drbd_bm_merge_lel(mdev, c->word_offset, num_words, buffer);

	c->word_offset += num_words;
	c->bit_offset = c->word_offset * BITS_PER_LONG;
	if (c->bit_offset > c->bm_bits)
		c->bit_offset = c->bm_bits;

	return OK;
}

static enum receive_bitmap_ret
recv_bm_rle_bits(struct drbd_conf *mdev,
		struct p_compressed_bm *p,
		struct bm_xfer_ctx *c)
{
	struct bitstream bs;
	u64 look_ahead;
	u64 rl;
	u64 tmp;
	unsigned long s = c->bit_offset;
	unsigned long e;
	int len = p->head.length - (sizeof(*p) - sizeof(p->head));
	int toggle = DCBP_get_start(p);
	int have;
	int bits;

	bitstream_init(&bs, p->code, len, DCBP_get_pad_bits(p));

	bits = bitstream_get_bits(&bs, &look_ahead, 64);
	if (bits < 0)
		return FAILED;

	for (have = bits; have > 0; s += rl, toggle = !toggle) {
		bits = vli_decode_bits(&rl, look_ahead);
		if (bits <= 0)
			return FAILED;

		if (toggle) {
			e = s + rl -1;
			if (e >= c->bm_bits) {
				dev_err(DEV, "bitmap overflow (e:%lu) while decoding bm RLE packet\n", e);
				return FAILED;
			}
			_drbd_bm_set_bits(mdev, s, e);
		}

		if (have < bits) {
			dev_err(DEV, "bitmap decoding error: h:%d b:%d la:0x%08llx l:%u/%u\n",
				have, bits, look_ahead,
				(unsigned int)(bs.cur.b - p->code),
				(unsigned int)bs.buf_len);
			return FAILED;
		}
		look_ahead >>= bits;
		have -= bits;

		bits = bitstream_get_bits(&bs, &tmp, 64 - have);
		if (bits < 0)
			return FAILED;
		look_ahead |= tmp << have;
		have += bits;
	}

	c->bit_offset = s;
	bm_xfer_ctx_bit_to_word_offset(c);

	return (s == c->bm_bits) ? DONE : OK;
}

static enum receive_bitmap_ret
decode_bitmap_c(struct drbd_conf *mdev,
		struct p_compressed_bm *p,
		struct bm_xfer_ctx *c)
{
	if (DCBP_get_code(p) == RLE_VLI_Bits)
		return recv_bm_rle_bits(mdev, p, c);

	/* other variants had been implemented for evaluation,
	 * but have been dropped as this one turned out to be "best"
	 * during all our tests. */

	dev_err(DEV, "receive_bitmap_c: unknown encoding %u\n", p->encoding);
	drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
	return FAILED;
}

void INFO_bm_xfer_stats(struct drbd_conf *mdev,
		const char *direction, struct bm_xfer_ctx *c)
{
	/* what would it take to transfer it "plaintext" */
	unsigned plain = sizeof(struct p_header) *
		((c->bm_words+BM_PACKET_WORDS-1)/BM_PACKET_WORDS+1)
		+ c->bm_words * sizeof(long);
	unsigned total = c->bytes[0] + c->bytes[1];
	unsigned r;

	/* total can not be zero. but just in case: */
	if (total == 0)
		return;

	/* don't report if not compressed */
	if (total >= plain)
		return;

	/* total < plain. check for overflow, still */
	r = (total > UINT_MAX/1000) ? (total / (plain/1000))
		                    : (1000 * total / plain);

	if (r > 1000)
		r = 1000;

	r = 1000 - r;
	dev_info(DEV, "%s bitmap stats [Bytes(packets)]: plain %u(%u), RLE %u(%u), "
	     "total %u; compression: %u.%u%%\n",
			direction,
			c->bytes[1], c->packets[1],
			c->bytes[0], c->packets[0],
			total, r/10, r % 10);
}

/* Since we are processing the bitfield from lower addresses to higher,
   it does not matter if the process it in 32 bit chunks or 64 bit
   chunks as long as it is little endian. (Understand it as byte stream,
   beginning with the lowest byte...) If we would use big endian
   we would need to process it from the highest address to the lowest,
   in order to be agnostic to the 32 vs 64 bits issue.

   returns 0 on failure, 1 if we successfully received it. */
static int receive_bitmap(struct drbd_conf *mdev, struct p_header *h)
{
	struct bm_xfer_ctx c;
	void *buffer;
	enum receive_bitmap_ret ret;
	int ok = FALSE;

	wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_bio_cnt));

	drbd_bm_lock(mdev, "receive bitmap");

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

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

	do {
		if (h->command == P_BITMAP) {
			ret = receive_bitmap_plain(mdev, h, buffer, &c);
		} else if (h->command == P_COMPRESSED_BITMAP) {
			/* MAYBE: sanity check that we speak proto >= 90,
			 * and the feature is enabled! */
			struct p_compressed_bm *p;

			if (h->length > BM_PACKET_PAYLOAD_BYTES) {
				dev_err(DEV, "ReportCBitmap packet too large\n");
				goto out;
			}
			/* use the page buff */
			p = buffer;
			memcpy(p, h, sizeof(*h));
			if (drbd_recv(mdev, p->head.payload, h->length) != h->length)
				goto out;
			if (p->head.length <= (sizeof(*p) - sizeof(p->head))) {
				dev_err(DEV, "ReportCBitmap packet too small (l:%u)\n", p->head.length);
				return FAILED;
			}
			ret = decode_bitmap_c(mdev, p, &c);
		} else {
			dev_warn(DEV, "receive_bitmap: h->command neither ReportBitMap nor ReportCBitMap (is 0x%x)", h->command);
			goto out;
		}

		c.packets[h->command == P_BITMAP]++;
		c.bytes[h->command == P_BITMAP] += sizeof(struct p_header) + h->length;

		if (ret != OK)
			break;

		if (!drbd_recv_header(mdev, h))
			goto out;
	} while (ret == OK);
	if (ret == FAILED)
		goto out;

	INFO_bm_xfer_stats(mdev, "receive", &c);

	if (mdev->state.conn == C_WF_BITMAP_T) {
		ok = !drbd_send_bitmap(mdev);
		if (!ok)
			goto out;
		/* Omit CS_ORDERED with this state transition to avoid deadlocks. */
		ok = _drbd_request_state(mdev, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE);
		D_ASSERT(ok == SS_SUCCESS);
	} else if (mdev->state.conn != C_WF_BITMAP_S) {
		/* admin may have requested C_DISCONNECTING,
		 * other threads may have noticed network errors */
		dev_info(DEV, "unexpected cstate (%s) in receive_bitmap\n",
		    drbd_conn_str(mdev->state.conn));
	}

	ok = TRUE;
 out:
	drbd_bm_unlock(mdev);
	if (ok && mdev->state.conn == C_WF_BITMAP_S)
		drbd_start_resync(mdev, C_SYNC_SOURCE);
	free_page((unsigned long) buffer);
	return ok;
}

static int receive_skip(struct drbd_conf *mdev, struct p_header *h)
{
	/* TODO zero copy sink :) */
	static char sink[128];
	int size, want, r;

	dev_warn(DEV, "skipping unknown optional packet type %d, l: %d!\n",
	     h->command, h->length);

	size = h->length;
	while (size > 0) {
		want = min_t(int, size, sizeof(sink));
		r = drbd_recv(mdev, sink, want);
		ERR_IF(r <= 0) break;
		size -= r;
	}
	return size == 0;
}

static int receive_UnplugRemote(struct drbd_conf *mdev, struct p_header *h)
{
	if (mdev->state.disk >= D_INCONSISTENT)
		drbd_kick_lo(mdev);

	/* Make sure we've acked all the TCP data associated
	 * with the data requests being unplugged */
	drbd_tcp_quickack(mdev->data.socket);

	return TRUE;
}

typedef int (*drbd_cmd_handler_f)(struct drbd_conf *, struct p_header *);

static drbd_cmd_handler_f drbd_default_handler[] = {
	[P_DATA]	    = receive_Data,
	[P_DATA_REPLY]	    = receive_DataReply,
	[P_RS_DATA_REPLY]   = receive_RSDataReply,
	[P_BARRIER]	    = receive_Barrier,
	[P_BITMAP]	    = receive_bitmap,
	[P_COMPRESSED_BITMAP]    = receive_bitmap,
	[P_UNPLUG_REMOTE]   = receive_UnplugRemote,
	[P_DATA_REQUEST]    = receive_DataRequest,
	[P_RS_DATA_REQUEST] = receive_DataRequest,
	[P_SYNC_PARAM]	    = receive_SyncParam,
	[P_SYNC_PARAM89]	   = receive_SyncParam,
	[P_PROTOCOL]        = receive_protocol,
	[P_UUIDS]	    = receive_uuids,
	[P_SIZES]	    = receive_sizes,
	[P_STATE]	    = receive_state,
	[P_STATE_CHG_REQ]   = receive_req_state,
	[P_SYNC_UUID]       = receive_sync_uuid,
	[P_OV_REQUEST]      = receive_DataRequest,
	[P_OV_REPLY]        = receive_DataRequest,
	[P_CSUM_RS_REQUEST]    = receive_DataRequest,
	/* anything missing from this table is in
	 * the asender_tbl, see get_asender_cmd */
	[P_MAX_CMD]	    = NULL,
};

static drbd_cmd_handler_f *drbd_cmd_handler = drbd_default_handler;
static drbd_cmd_handler_f *drbd_opt_cmd_handler;

static void drbdd(struct drbd_conf *mdev)
{
	drbd_cmd_handler_f handler;
	struct p_header *header = &mdev->data.rbuf.header;

	while (get_t_state(&mdev->receiver) == Running) {
		drbd_thread_current_set_cpu(mdev);
		if (!drbd_recv_header(mdev, header)) {
			drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
			break;
		}

		if (header->command < P_MAX_CMD)
			handler = drbd_cmd_handler[header->command];
		else if (P_MAY_IGNORE < header->command
		     && header->command < P_MAX_OPT_CMD)
			handler = drbd_opt_cmd_handler[header->command-P_MAY_IGNORE];
		else if (header->command > P_MAX_OPT_CMD)
			handler = receive_skip;
		else
			handler = NULL;

		if (unlikely(!handler)) {
			dev_err(DEV, "unknown packet type %d, l: %d!\n",
			    header->command, header->length);
			drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
			break;
		}
		if (unlikely(!handler(mdev, header))) {
			dev_err(DEV, "error receiving %s, l: %d!\n",
			    cmdname(header->command), header->length);
			drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
			break;
		}
	}
}

static void drbd_fail_pending_reads(struct drbd_conf *mdev)
{
	struct hlist_head *slot;
	struct hlist_node *pos;
	struct hlist_node *tmp;
	struct drbd_request *req;
	int i;

	/*
	 * Application READ requests
	 */
	spin_lock_irq(&mdev->req_lock);
	for (i = 0; i < APP_R_HSIZE; i++) {
		slot = mdev->app_reads_hash+i;
		hlist_for_each_entry_safe(req, pos, tmp, slot, colision) {
			/* it may (but should not any longer!)
			 * be on the work queue; if that assert triggers,
			 * we need to also grab the
			 * spin_lock_irq(&mdev->data.work.q_lock);
			 * and list_del_init here. */
			D_ASSERT(list_empty(&req->w.list));
			/* It would be nice to complete outside of spinlock.
			 * But this is easier for now. */
			_req_mod(req, connection_lost_while_pending);
		}
	}
	for (i = 0; i < APP_R_HSIZE; i++)
		if (!hlist_empty(mdev->app_reads_hash+i))
			dev_warn(DEV, "ASSERT FAILED: app_reads_hash[%d].first: "
				"%p, should be NULL\n", i, mdev->app_reads_hash[i].first);

	memset(mdev->app_reads_hash, 0, APP_R_HSIZE*sizeof(void *));
	spin_unlock_irq(&mdev->req_lock);
}

void drbd_flush_workqueue(struct drbd_conf *mdev)
{
	struct drbd_wq_barrier barr;

	barr.w.cb = w_prev_work_done;
	init_completion(&barr.done);
	drbd_queue_work(&mdev->data.work, &barr.w);
	wait_for_completion(&barr.done);
}

static void drbd_disconnect(struct drbd_conf *mdev)
{
	enum drbd_fencing_p fp;
	union drbd_state os, ns;
	int rv = SS_UNKNOWN_ERROR;
	unsigned int i;

	if (mdev->state.conn == C_STANDALONE)
		return;
	if (mdev->state.conn >= C_WF_CONNECTION)
		dev_err(DEV, "ASSERT FAILED cstate = %s, expected < WFConnection\n",
				drbd_conn_str(mdev->state.conn));

	/* asender does not clean up anything. it must not interfere, either */
	drbd_thread_stop(&mdev->asender);
	drbd_free_sock(mdev);

	spin_lock_irq(&mdev->req_lock);
	_drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
	_drbd_wait_ee_list_empty(mdev, &mdev->sync_ee);
	_drbd_wait_ee_list_empty(mdev, &mdev->read_ee);
	spin_unlock_irq(&mdev->req_lock);

	/* We do not have data structures that would allow us to
	 * get the rs_pending_cnt down to 0 again.
	 *  * On C_SYNC_TARGET we do not have any data structures describing
	 *    the pending RSDataRequest's we have sent.
	 *  * On C_SYNC_SOURCE there is no data structure that tracks
	 *    the P_RS_DATA_REPLY blocks that we sent to the SyncTarget.
	 *  And no, it is not the sum of the reference counts in the
	 *  resync_LRU. The resync_LRU tracks the whole operation including
	 *  the disk-IO, while the rs_pending_cnt only tracks the blocks
	 *  on the fly. */
	drbd_rs_cancel_all(mdev);
	mdev->rs_total = 0;
	mdev->rs_failed = 0;
	atomic_set(&mdev->rs_pending_cnt, 0);
	wake_up(&mdev->misc_wait);

	/* make sure syncer is stopped and w_resume_next_sg queued */
	del_timer_sync(&mdev->resync_timer);
	set_bit(STOP_SYNC_TIMER, &mdev->flags);
	resync_timer_fn((unsigned long)mdev);

	/* wait for all w_e_end_data_req, w_e_end_rsdata_req, w_send_barrier,
	 * w_make_resync_request etc. which may still be on the worker queue
	 * to be "canceled" */
	drbd_flush_workqueue(mdev);

	/* This also does reclaim_net_ee().  If we do this too early, we might
	 * miss some resync ee and pages.*/
	drbd_process_done_ee(mdev);

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

	if (!mdev->state.susp)
		tl_clear(mdev);

	drbd_fail_pending_reads(mdev);

	dev_info(DEV, "Connection closed\n");

	drbd_md_sync(mdev);

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

	if (mdev->state.role == R_PRIMARY) {
		if (fp >= FP_RESOURCE && mdev->state.pdsk >= D_UNKNOWN) {
			enum drbd_disk_state nps = drbd_try_outdate_peer(mdev);
			drbd_request_state(mdev, NS(pdsk, nps));
		}
	}

	spin_lock_irq(&mdev->req_lock);
	os = mdev->state;
	if (os.conn >= C_UNCONNECTED) {
		/* Do not restart in case we are C_DISCONNECTING */
		ns = os;
		ns.conn = C_UNCONNECTED;
		rv = _drbd_set_state(mdev, ns, CS_VERBOSE, NULL);
	}
	spin_unlock_irq(&mdev->req_lock);

	if (os.conn == C_DISCONNECTING) {
		struct hlist_head *h;
		wait_event(mdev->misc_wait, atomic_read(&mdev->net_cnt) == 0);

		/* we must not free the tl_hash
		 * while application io is still on the fly */
		wait_event(mdev->misc_wait, atomic_read(&mdev->ap_bio_cnt) == 0);

		spin_lock_irq(&mdev->req_lock);
		/* paranoia code */
		for (h = mdev->ee_hash; h < mdev->ee_hash + mdev->ee_hash_s; h++)
			if (h->first)
				dev_err(DEV, "ASSERT FAILED ee_hash[%u].first == %p, expected NULL\n",
						(int)(h - mdev->ee_hash), h->first);
		kfree(mdev->ee_hash);
		mdev->ee_hash = NULL;
		mdev->ee_hash_s = 0;

		/* paranoia code */
		for (h = mdev->tl_hash; h < mdev->tl_hash + mdev->tl_hash_s; h++)
			if (h->first)
				dev_err(DEV, "ASSERT FAILED tl_hash[%u] == %p, expected NULL\n",
						(int)(h - mdev->tl_hash), h->first);
		kfree(mdev->tl_hash);
		mdev->tl_hash = NULL;
		mdev->tl_hash_s = 0;
		spin_unlock_irq(&mdev->req_lock);

		crypto_free_hash(mdev->cram_hmac_tfm);
		mdev->cram_hmac_tfm = NULL;

		kfree(mdev->net_conf);
		mdev->net_conf = NULL;
		drbd_request_state(mdev, NS(conn, C_STANDALONE));
	}

	/* tcp_close and release of sendpage pages can be deferred.  I don't
	 * want to use SO_LINGER, because apparently it can be deferred for
	 * more than 20 seconds (longest time I checked).
	 *
	 * Actually we don't care for exactly when the network stack does its
	 * put_page(), but release our reference on these pages right here.
	 */
	i = drbd_release_ee(mdev, &mdev->net_ee);
	if (i)
		dev_info(DEV, "net_ee not empty, killed %u entries\n", i);
	i = atomic_read(&mdev->pp_in_use);
	if (i)
		dev_info(DEV, "pp_in_use = %u, expected 0\n", i);

	D_ASSERT(list_empty(&mdev->read_ee));
	D_ASSERT(list_empty(&mdev->active_ee));
	D_ASSERT(list_empty(&mdev->sync_ee));
	D_ASSERT(list_empty(&mdev->done_ee));

	/* ok, no more ee's on the fly, it is safe to reset the epoch_size */
	atomic_set(&mdev->current_epoch->epoch_size, 0);
	D_ASSERT(list_empty(&mdev->current_epoch->list));
}

/*
 * We support PRO_VERSION_MIN to PRO_VERSION_MAX. The protocol version
 * we can agree on is stored in agreed_pro_version.
 *
 * feature flags and the reserved array should be enough room for future
 * enhancements of the handshake protocol, and possible plugins...
 *
 * for now, they are expected to be zero, but ignored.
 */
static int drbd_send_handshake(struct drbd_conf *mdev)
{
	/* ASSERT current == mdev->receiver ... */
	struct p_handshake *p = &mdev->data.sbuf.handshake;
	int ok;

	if (mutex_lock_interruptible(&mdev->data.mutex)) {
		dev_err(DEV, "interrupted during initial handshake\n");
		return 0; /* interrupted. not ok. */
	}

	if (mdev->data.socket == NULL) {
		mutex_unlock(&mdev->data.mutex);
		return 0;
	}

	memset(p, 0, sizeof(*p));
	p->protocol_min = cpu_to_be32(PRO_VERSION_MIN);
	p->protocol_max = cpu_to_be32(PRO_VERSION_MAX);
	ok = _drbd_send_cmd( mdev, mdev->data.socket, P_HAND_SHAKE,
			     (struct p_header *)p, sizeof(*p), 0 );
	mutex_unlock(&mdev->data.mutex);
	return ok;
}

/*
 * return values:
 *   1 yes, we have a valid connection
 *   0 oops, did not work out, please try again
 *  -1 peer talks different language,
 *     no point in trying again, please go standalone.
 */
static int drbd_do_handshake(struct drbd_conf *mdev)
{
	/* ASSERT current == mdev->receiver ... */
	struct p_handshake *p = &mdev->data.rbuf.handshake;
	const int expect = sizeof(struct p_handshake)
			  -sizeof(struct p_header);
	int rv;

	rv = drbd_send_handshake(mdev);
	if (!rv)
		return 0;

	rv = drbd_recv_header(mdev, &p->head);
	if (!rv)
		return 0;

	if (p->head.command != P_HAND_SHAKE) {
		dev_err(DEV, "expected HandShake packet, received: %s (0x%04x)\n",
		     cmdname(p->head.command), p->head.command);
		return -1;
	}

	if (p->head.length != expect) {
		dev_err(DEV, "expected HandShake length: %u, received: %u\n",
		     expect, p->head.length);
		return -1;
	}

	rv = drbd_recv(mdev, &p->head.payload, expect);

	if (rv != expect) {
		dev_err(DEV, "short read receiving handshake packet: l=%u\n", rv);
		return 0;
	}

	p->protocol_min = be32_to_cpu(p->protocol_min);
	p->protocol_max = be32_to_cpu(p->protocol_max);
	if (p->protocol_max == 0)
		p->protocol_max = p->protocol_min;

	if (PRO_VERSION_MAX < p->protocol_min ||
	    PRO_VERSION_MIN > p->protocol_max)
		goto incompat;

	mdev->agreed_pro_version = min_t(int, PRO_VERSION_MAX, p->protocol_max);

	dev_info(DEV, "Handshake successful: "
	     "Agreed network protocol version %d\n", mdev->agreed_pro_version);

	return 1;

 incompat:
	dev_err(DEV, "incompatible DRBD dialects: "
	    "I support %d-%d, peer supports %d-%d\n",
	    PRO_VERSION_MIN, PRO_VERSION_MAX,
	    p->protocol_min, p->protocol_max);
	return -1;
}

#if !defined(CONFIG_CRYPTO_HMAC) && !defined(CONFIG_CRYPTO_HMAC_MODULE)
static int drbd_do_auth(struct drbd_conf *mdev)
{
	dev_err(DEV, "This kernel was build without CONFIG_CRYPTO_HMAC.\n");
	dev_err(DEV, "You need to disable 'cram-hmac-alg' in drbd.conf.\n");
	return -1;
}
#else
#define CHALLENGE_LEN 64

/* Return value:
	1 - auth succeeded,
	0 - failed, try again (network error),
	-1 - auth failed, don't try again.
*/

static int drbd_do_auth(struct drbd_conf *mdev)
{
	char my_challenge[CHALLENGE_LEN];  /* 64 Bytes... */
	struct scatterlist sg;
	char *response = NULL;
	char *right_response = NULL;
	char *peers_ch = NULL;
	struct p_header p;
	unsigned int key_len = strlen(mdev->net_conf->shared_secret);
	unsigned int resp_size;
	struct hash_desc desc;
	int rv;

	desc.tfm = mdev->cram_hmac_tfm;
	desc.flags = 0;

	rv = crypto_hash_setkey(mdev->cram_hmac_tfm,
				(u8 *)mdev->net_conf->shared_secret, key_len);
	if (rv) {
		dev_err(DEV, "crypto_hash_setkey() failed with %d\n", rv);
		rv = -1;
		goto fail;
	}

	get_random_bytes(my_challenge, CHALLENGE_LEN);

	rv = drbd_send_cmd2(mdev, P_AUTH_CHALLENGE, my_challenge, CHALLENGE_LEN);
	if (!rv)
		goto fail;

	rv = drbd_recv_header(mdev, &p);
	if (!rv)
		goto fail;

	if (p.command != P_AUTH_CHALLENGE) {
		dev_err(DEV, "expected AuthChallenge packet, received: %s (0x%04x)\n",
		    cmdname(p.command), p.command);
		rv = 0;
		goto fail;
	}

	if (p.length > CHALLENGE_LEN*2) {
		dev_err(DEV, "expected AuthChallenge payload too big.\n");
		rv = -1;
		goto fail;
	}

	peers_ch = kmalloc(p.length, GFP_NOIO);
	if (peers_ch == NULL) {
		dev_err(DEV, "kmalloc of peers_ch failed\n");
		rv = -1;
		goto fail;
	}

	rv = drbd_recv(mdev, peers_ch, p.length);

	if (rv != p.length) {
		dev_err(DEV, "short read AuthChallenge: l=%u\n", rv);
		rv = 0;
		goto fail;
	}

	resp_size = crypto_hash_digestsize(mdev->cram_hmac_tfm);
	response = kmalloc(resp_size, GFP_NOIO);
	if (response == NULL) {
		dev_err(DEV, "kmalloc of response failed\n");
		rv = -1;
		goto fail;
	}

	sg_init_table(&sg, 1);
	sg_set_buf(&sg, peers_ch, p.length);

	rv = crypto_hash_digest(&desc, &sg, sg.length, response);
	if (rv) {
		dev_err(DEV, "crypto_hash_digest() failed with %d\n", rv);
		rv = -1;
		goto fail;
	}

	rv = drbd_send_cmd2(mdev, P_AUTH_RESPONSE, response, resp_size);
	if (!rv)
		goto fail;

	rv = drbd_recv_header(mdev, &p);
	if (!rv)
		goto fail;

	if (p.command != P_AUTH_RESPONSE) {
		dev_err(DEV, "expected AuthResponse packet, received: %s (0x%04x)\n",
		    cmdname(p.command), p.command);
		rv = 0;
		goto fail;
	}

	if (p.length != resp_size) {
		dev_err(DEV, "expected AuthResponse payload of wrong size\n");
		rv = 0;
		goto fail;
	}

	rv = drbd_recv(mdev, response , resp_size);

	if (rv != resp_size) {
		dev_err(DEV, "short read receiving AuthResponse: l=%u\n", rv);
		rv = 0;
		goto fail;
	}

	right_response = kmalloc(resp_size, GFP_NOIO);
	if (right_response == NULL) {
		dev_err(DEV, "kmalloc of right_response failed\n");
		rv = -1;
		goto fail;
	}

	sg_set_buf(&sg, my_challenge, CHALLENGE_LEN);

	rv = crypto_hash_digest(&desc, &sg, sg.length, right_response);
	if (rv) {
		dev_err(DEV, "crypto_hash_digest() failed with %d\n", rv);
		rv = -1;
		goto fail;
	}

	rv = !memcmp(response, right_response, resp_size);

	if (rv)
		dev_info(DEV, "Peer authenticated using %d bytes of '%s' HMAC\n",
		     resp_size, mdev->net_conf->cram_hmac_alg);
	else
		rv = -1;

 fail:
	kfree(peers_ch);
	kfree(response);
	kfree(right_response);

	return rv;
}
#endif

int drbdd_init(struct drbd_thread *thi)
{
	struct drbd_conf *mdev = thi->mdev;
	unsigned int minor = mdev_to_minor(mdev);
	int h;

	sprintf(current->comm, "drbd%d_receiver", minor);

	dev_info(DEV, "receiver (re)started\n");

	do {
		h = drbd_connect(mdev);
		if (h == 0) {
			drbd_disconnect(mdev);
			__set_current_state(TASK_INTERRUPTIBLE);
			schedule_timeout(HZ);
		}
		if (h == -1) {
			dev_warn(DEV, "Discarding network configuration.\n");
			drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
		}
	} while (h == 0);

	if (h > 0) {
		if (get_net_conf(mdev)) {
			drbdd(mdev);
			put_net_conf(mdev);
		}
	}

	drbd_disconnect(mdev);

	dev_info(DEV, "receiver terminated\n");
	return 0;
}

/* ********* acknowledge sender ******** */

static int got_RqSReply(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_req_state_reply *p = (struct p_req_state_reply *)h;

	int retcode = be32_to_cpu(p->retcode);

	if (retcode >= SS_SUCCESS) {
		set_bit(CL_ST_CHG_SUCCESS, &mdev->flags);
	} else {
		set_bit(CL_ST_CHG_FAIL, &mdev->flags);
		dev_err(DEV, "Requested state change failed by peer: %s (%d)\n",
		    drbd_set_st_err_str(retcode), retcode);
	}
	wake_up(&mdev->state_wait);

	return TRUE;
}

static int got_Ping(struct drbd_conf *mdev, struct p_header *h)
{
	return drbd_send_ping_ack(mdev);

}

static int got_PingAck(struct drbd_conf *mdev, struct p_header *h)
{
	/* restore idle timeout */
	mdev->meta.socket->sk->sk_rcvtimeo = mdev->net_conf->ping_int*HZ;
	if (!test_and_set_bit(GOT_PING_ACK, &mdev->flags))
		wake_up(&mdev->misc_wait);

	return TRUE;
}

static int got_IsInSync(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_block_ack *p = (struct p_block_ack *)h;
	sector_t sector = be64_to_cpu(p->sector);
	int blksize = be32_to_cpu(p->blksize);

	D_ASSERT(mdev->agreed_pro_version >= 89);

	update_peer_seq(mdev, be32_to_cpu(p->seq_num));

	drbd_rs_complete_io(mdev, sector);
	drbd_set_in_sync(mdev, sector, blksize);
	/* rs_same_csums is supposed to count in units of BM_BLOCK_SIZE */
	mdev->rs_same_csum += (blksize >> BM_BLOCK_SHIFT);
	dec_rs_pending(mdev);

	return TRUE;
}

/* when we receive the ACK for a write request,
 * verify that we actually know about it */
static struct drbd_request *_ack_id_to_req(struct drbd_conf *mdev,
	u64 id, sector_t sector)
{
	struct hlist_head *slot = tl_hash_slot(mdev, sector);
	struct hlist_node *n;
	struct drbd_request *req;

	hlist_for_each_entry(req, n, slot, colision) {
		if ((unsigned long)req == (unsigned long)id) {
			if (req->sector != sector) {
				dev_err(DEV, "_ack_id_to_req: found req %p but it has "
				    "wrong sector (%llus versus %llus)\n", req,
				    (unsigned long long)req->sector,
				    (unsigned long long)sector);
				break;
			}
			return req;
		}
	}
	dev_err(DEV, "_ack_id_to_req: failed to find req %p, sector %llus in list\n",
		(void *)(unsigned long)id, (unsigned long long)sector);
	return NULL;
}

typedef struct drbd_request *(req_validator_fn)
	(struct drbd_conf *mdev, u64 id, sector_t sector);

static int validate_req_change_req_state(struct drbd_conf *mdev,
	u64 id, sector_t sector, req_validator_fn validator,
	const char *func, enum drbd_req_event what)
{
	struct drbd_request *req;
	struct bio_and_error m;

	spin_lock_irq(&mdev->req_lock);
	req = validator(mdev, id, sector);
	if (unlikely(!req)) {
		spin_unlock_irq(&mdev->req_lock);
		dev_err(DEV, "%s: got a corrupt block_id/sector pair\n", func);
		return FALSE;
	}
	__req_mod(req, what, &m);
	spin_unlock_irq(&mdev->req_lock);

	if (m.bio)
		complete_master_bio(mdev, &m);
	return TRUE;
}

static int got_BlockAck(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_block_ack *p = (struct p_block_ack *)h;
	sector_t sector = be64_to_cpu(p->sector);
	int blksize = be32_to_cpu(p->blksize);
	enum drbd_req_event what;

	update_peer_seq(mdev, be32_to_cpu(p->seq_num));

	if (is_syncer_block_id(p->block_id)) {
		drbd_set_in_sync(mdev, sector, blksize);
		dec_rs_pending(mdev);
		return TRUE;
	}
	switch (be16_to_cpu(h->command)) {
	case P_RS_WRITE_ACK:
		D_ASSERT(mdev->net_conf->wire_protocol == DRBD_PROT_C);
		what = write_acked_by_peer_and_sis;
		break;
	case P_WRITE_ACK:
		D_ASSERT(mdev->net_conf->wire_protocol == DRBD_PROT_C);
		what = write_acked_by_peer;
		break;
	case P_RECV_ACK:
		D_ASSERT(mdev->net_conf->wire_protocol == DRBD_PROT_B);
		what = recv_acked_by_peer;
		break;
	case P_DISCARD_ACK:
		D_ASSERT(mdev->net_conf->wire_protocol == DRBD_PROT_C);
		what = conflict_discarded_by_peer;
		break;
	default:
		D_ASSERT(0);
		return FALSE;
	}

	return validate_req_change_req_state(mdev, p->block_id, sector,
		_ack_id_to_req, __func__ , what);
}

static int got_NegAck(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_block_ack *p = (struct p_block_ack *)h;
	sector_t sector = be64_to_cpu(p->sector);

	if (__ratelimit(&drbd_ratelimit_state))
		dev_warn(DEV, "Got NegAck packet. Peer is in troubles?\n");

	update_peer_seq(mdev, be32_to_cpu(p->seq_num));

	if (is_syncer_block_id(p->block_id)) {
		int size = be32_to_cpu(p->blksize);
		dec_rs_pending(mdev);
		drbd_rs_failed_io(mdev, sector, size);
		return TRUE;
	}
	return validate_req_change_req_state(mdev, p->block_id, sector,
		_ack_id_to_req, __func__ , neg_acked);
}

static int got_NegDReply(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_block_ack *p = (struct p_block_ack *)h;
	sector_t sector = be64_to_cpu(p->sector);

	update_peer_seq(mdev, be32_to_cpu(p->seq_num));
	dev_err(DEV, "Got NegDReply; Sector %llus, len %u; Fail original request.\n",
	    (unsigned long long)sector, be32_to_cpu(p->blksize));

	return validate_req_change_req_state(mdev, p->block_id, sector,
		_ar_id_to_req, __func__ , neg_acked);
}

static int got_NegRSDReply(struct drbd_conf *mdev, struct p_header *h)
{
	sector_t sector;
	int size;
	struct p_block_ack *p = (struct p_block_ack *)h;

	sector = be64_to_cpu(p->sector);
	size = be32_to_cpu(p->blksize);
	D_ASSERT(p->block_id == ID_SYNCER);

	update_peer_seq(mdev, be32_to_cpu(p->seq_num));

	dec_rs_pending(mdev);

	if (get_ldev_if_state(mdev, D_FAILED)) {
		drbd_rs_complete_io(mdev, sector);
		drbd_rs_failed_io(mdev, sector, size);
		put_ldev(mdev);
	}

	return TRUE;
}

static int got_BarrierAck(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_barrier_ack *p = (struct p_barrier_ack *)h;

	tl_release(mdev, p->barrier, be32_to_cpu(p->set_size));

	return TRUE;
}

static int got_OVResult(struct drbd_conf *mdev, struct p_header *h)
{
	struct p_block_ack *p = (struct p_block_ack *)h;
	struct drbd_work *w;
	sector_t sector;
	int size;

	sector = be64_to_cpu(p->sector);
	size = be32_to_cpu(p->blksize);

	update_peer_seq(mdev, be32_to_cpu(p->seq_num));

	if (be64_to_cpu(p->block_id) == ID_OUT_OF_SYNC)
		drbd_ov_oos_found(mdev, sector, size);
	else
		ov_oos_print(mdev);

	drbd_rs_complete_io(mdev, sector);
	dec_rs_pending(mdev);

	if (--mdev->ov_left == 0) {
		w = kmalloc(sizeof(*w), GFP_NOIO);
		if (w) {
			w->cb = w_ov_finished;
			drbd_queue_work_front(&mdev->data.work, w);
		} else {
			dev_err(DEV, "kmalloc(w) failed.");
			ov_oos_print(mdev);
			drbd_resync_finished(mdev);
		}
	}
	return TRUE;
}

struct asender_cmd {
	size_t pkt_size;
	int (*process)(struct drbd_conf *mdev, struct p_header *h);
};

static struct asender_cmd *get_asender_cmd(int cmd)
{
	static struct asender_cmd asender_tbl[] = {
		/* anything missing from this table is in
		 * the drbd_cmd_handler (drbd_default_handler) table,
		 * see the beginning of drbdd() */
	[P_PING]	    = { sizeof(struct p_header), got_Ping },
	[P_PING_ACK]	    = { sizeof(struct p_header), got_PingAck },
	[P_RECV_ACK]	    = { sizeof(struct p_block_ack), got_BlockAck },
	[P_WRITE_ACK]	    = { sizeof(struct p_block_ack), got_BlockAck },
	[P_RS_WRITE_ACK]    = { sizeof(struct p_block_ack), got_BlockAck },
	[P_DISCARD_ACK]	    = { sizeof(struct p_block_ack), got_BlockAck },
	[P_NEG_ACK]	    = { sizeof(struct p_block_ack), got_NegAck },
	[P_NEG_DREPLY]	    = { sizeof(struct p_block_ack), got_NegDReply },
	[P_NEG_RS_DREPLY]   = { sizeof(struct p_block_ack), got_NegRSDReply},
	[P_OV_RESULT]	    = { sizeof(struct p_block_ack), got_OVResult },
	[P_BARRIER_ACK]	    = { sizeof(struct p_barrier_ack), got_BarrierAck },
	[P_STATE_CHG_REPLY] = { sizeof(struct p_req_state_reply), got_RqSReply },
	[P_RS_IS_IN_SYNC]   = { sizeof(struct p_block_ack), got_IsInSync },
	[P_MAX_CMD]	    = { 0, NULL },
	};
	if (cmd > P_MAX_CMD || asender_tbl[cmd].process == NULL)
		return NULL;
	return &asender_tbl[cmd];
}

int drbd_asender(struct drbd_thread *thi)
{
	struct drbd_conf *mdev = thi->mdev;
	struct p_header *h = &mdev->meta.rbuf.header;
	struct asender_cmd *cmd = NULL;

	int rv, len;
	void *buf    = h;
	int received = 0;
	int expect   = sizeof(struct p_header);
	int empty;

	sprintf(current->comm, "drbd%d_asender", mdev_to_minor(mdev));

	current->policy = SCHED_RR;  /* Make this a realtime task! */
	current->rt_priority = 2;    /* more important than all other tasks */

	while (get_t_state(thi) == Running) {
		drbd_thread_current_set_cpu(mdev);
		if (test_and_clear_bit(SEND_PING, &mdev->flags)) {
			ERR_IF(!drbd_send_ping(mdev)) goto reconnect;
			mdev->meta.socket->sk->sk_rcvtimeo =
				mdev->net_conf->ping_timeo*HZ/10;
		}

		/* conditionally cork;
		 * it may hurt latency if we cork without much to send */
		if (!mdev->net_conf->no_cork &&
			3 < atomic_read(&mdev->unacked_cnt))
			drbd_tcp_cork(mdev->meta.socket);
		while (1) {
			clear_bit(SIGNAL_ASENDER, &mdev->flags);
			flush_signals(current);
			if (!drbd_process_done_ee(mdev)) {
				dev_err(DEV, "process_done_ee() = NOT_OK\n");
				goto reconnect;
			}
			/* to avoid race with newly queued ACKs */
			set_bit(SIGNAL_ASENDER, &mdev->flags);
			spin_lock_irq(&mdev->req_lock);
			empty = list_empty(&mdev->done_ee);
			spin_unlock_irq(&mdev->req_lock);
			/* new ack may have been queued right here,
			 * but then there is also a signal pending,
			 * and we start over... */
			if (empty)
				break;
		}
		/* but unconditionally uncork unless disabled */
		if (!mdev->net_conf->no_cork)
			drbd_tcp_uncork(mdev->meta.socket);

		/* short circuit, recv_msg would return EINTR anyways. */
		if (signal_pending(current))
			continue;

		rv = drbd_recv_short(mdev, mdev->meta.socket,
				     buf, expect-received, 0);
		clear_bit(SIGNAL_ASENDER, &mdev->flags);

		flush_signals(current);

		/* Note:
		 * -EINTR	 (on meta) we got a signal
		 * -EAGAIN	 (on meta) rcvtimeo expired
		 * -ECONNRESET	 other side closed the connection
		 * -ERESTARTSYS  (on data) we got a signal
		 * rv <  0	 other than above: unexpected error!
		 * rv == expected: full header or command
		 * rv <  expected: "woken" by signal during receive
		 * rv == 0	 : "connection shut down by peer"
		 */
		if (likely(rv > 0)) {
			received += rv;
			buf	 += rv;
		} else if (rv == 0) {
			dev_err(DEV, "meta connection shut down by peer.\n");
			goto reconnect;
		} else if (rv == -EAGAIN) {
			if (mdev->meta.socket->sk->sk_rcvtimeo ==
			    mdev->net_conf->ping_timeo*HZ/10) {
				dev_err(DEV, "PingAck did not arrive in time.\n");
				goto reconnect;
			}
			set_bit(SEND_PING, &mdev->flags);
			continue;
		} else if (rv == -EINTR) {
			continue;
		} else {
			dev_err(DEV, "sock_recvmsg returned %d\n", rv);
			goto reconnect;
		}

		if (received == expect && cmd == NULL) {
			if (unlikely(h->magic != BE_DRBD_MAGIC)) {
				dev_err(DEV, "magic?? on meta m: 0x%lx c: %d l: %d\n",
				    (long)be32_to_cpu(h->magic),
				    h->command, h->length);
				goto reconnect;
			}
			cmd = get_asender_cmd(be16_to_cpu(h->command));
			len = be16_to_cpu(h->length);
			if (unlikely(cmd == NULL)) {
				dev_err(DEV, "unknown command?? on meta m: 0x%lx c: %d l: %d\n",
				    (long)be32_to_cpu(h->magic),
				    h->command, h->length);
				goto disconnect;
			}
			expect = cmd->pkt_size;
			ERR_IF(len != expect-sizeof(struct p_header))
				goto reconnect;
		}
		if (received == expect) {
			D_ASSERT(cmd != NULL);
			if (!cmd->process(mdev, h))
				goto reconnect;

			buf	 = h;
			received = 0;
			expect	 = sizeof(struct p_header);
			cmd	 = NULL;
		}
	}

	if (0) {
reconnect:
		drbd_force_state(mdev, NS(conn, C_NETWORK_FAILURE));
	}
	if (0) {
disconnect:
		drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
	}
	clear_bit(SIGNAL_ASENDER, &mdev->flags);

	D_ASSERT(mdev->state.conn < C_CONNECTED);
	dev_info(DEV, "asender terminated\n");

	return 0;
}