summaryrefslogtreecommitdiff
path: root/fs/dlm/lock.c
blob: b93df39d09153d1c0617a5687017fc6aab0ae131 (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
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) 2005-2010 Red Hat, Inc.  All rights reserved.
**
**
*******************************************************************************
******************************************************************************/

/* Central locking logic has four stages:

   dlm_lock()
   dlm_unlock()

   request_lock(ls, lkb)
   convert_lock(ls, lkb)
   unlock_lock(ls, lkb)
   cancel_lock(ls, lkb)

   _request_lock(r, lkb)
   _convert_lock(r, lkb)
   _unlock_lock(r, lkb)
   _cancel_lock(r, lkb)

   do_request(r, lkb)
   do_convert(r, lkb)
   do_unlock(r, lkb)
   do_cancel(r, lkb)

   Stage 1 (lock, unlock) is mainly about checking input args and
   splitting into one of the four main operations:

       dlm_lock          = request_lock
       dlm_lock+CONVERT  = convert_lock
       dlm_unlock        = unlock_lock
       dlm_unlock+CANCEL = cancel_lock

   Stage 2, xxxx_lock(), just finds and locks the relevant rsb which is
   provided to the next stage.

   Stage 3, _xxxx_lock(), determines if the operation is local or remote.
   When remote, it calls send_xxxx(), when local it calls do_xxxx().

   Stage 4, do_xxxx(), is the guts of the operation.  It manipulates the
   given rsb and lkb and queues callbacks.

   For remote operations, send_xxxx() results in the corresponding do_xxxx()
   function being executed on the remote node.  The connecting send/receive
   calls on local (L) and remote (R) nodes:

   L: send_xxxx()              ->  R: receive_xxxx()
                                   R: do_xxxx()
   L: receive_xxxx_reply()     <-  R: send_xxxx_reply()
*/
#include <linux/types.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include "dlm_internal.h"
#include <linux/dlm_device.h>
#include "memory.h"
#include "lowcomms.h"
#include "requestqueue.h"
#include "util.h"
#include "dir.h"
#include "member.h"
#include "lockspace.h"
#include "ast.h"
#include "lock.h"
#include "rcom.h"
#include "recover.h"
#include "lvb_table.h"
#include "user.h"
#include "config.h"

static int send_request(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int send_convert(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int send_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int send_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int send_grant(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int send_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int mode);
static int send_lookup(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int send_remove(struct dlm_rsb *r);
static int _request_lock(struct dlm_rsb *r, struct dlm_lkb *lkb);
static int _cancel_lock(struct dlm_rsb *r, struct dlm_lkb *lkb);
static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
				    struct dlm_message *ms);
static int receive_extralen(struct dlm_message *ms);
static void do_purge(struct dlm_ls *ls, int nodeid, int pid);
static void del_timeout(struct dlm_lkb *lkb);
static void toss_rsb(struct kref *kref);

/*
 * Lock compatibilty matrix - thanks Steve
 * UN = Unlocked state. Not really a state, used as a flag
 * PD = Padding. Used to make the matrix a nice power of two in size
 * Other states are the same as the VMS DLM.
 * Usage: matrix[grmode+1][rqmode+1]  (although m[rq+1][gr+1] is the same)
 */

static const int __dlm_compat_matrix[8][8] = {
      /* UN NL CR CW PR PW EX PD */
        {1, 1, 1, 1, 1, 1, 1, 0},       /* UN */
        {1, 1, 1, 1, 1, 1, 1, 0},       /* NL */
        {1, 1, 1, 1, 1, 1, 0, 0},       /* CR */
        {1, 1, 1, 1, 0, 0, 0, 0},       /* CW */
        {1, 1, 1, 0, 1, 0, 0, 0},       /* PR */
        {1, 1, 1, 0, 0, 0, 0, 0},       /* PW */
        {1, 1, 0, 0, 0, 0, 0, 0},       /* EX */
        {0, 0, 0, 0, 0, 0, 0, 0}        /* PD */
};

/*
 * This defines the direction of transfer of LVB data.
 * Granted mode is the row; requested mode is the column.
 * Usage: matrix[grmode+1][rqmode+1]
 * 1 = LVB is returned to the caller
 * 0 = LVB is written to the resource
 * -1 = nothing happens to the LVB
 */

const int dlm_lvb_operations[8][8] = {
        /* UN   NL  CR  CW  PR  PW  EX  PD*/
        {  -1,  1,  1,  1,  1,  1,  1, -1 }, /* UN */
        {  -1,  1,  1,  1,  1,  1,  1,  0 }, /* NL */
        {  -1, -1,  1,  1,  1,  1,  1,  0 }, /* CR */
        {  -1, -1, -1,  1,  1,  1,  1,  0 }, /* CW */
        {  -1, -1, -1, -1,  1,  1,  1,  0 }, /* PR */
        {  -1,  0,  0,  0,  0,  0,  1,  0 }, /* PW */
        {  -1,  0,  0,  0,  0,  0,  0,  0 }, /* EX */
        {  -1,  0,  0,  0,  0,  0,  0,  0 }  /* PD */
};

#define modes_compat(gr, rq) \
	__dlm_compat_matrix[(gr)->lkb_grmode + 1][(rq)->lkb_rqmode + 1]

int dlm_modes_compat(int mode1, int mode2)
{
	return __dlm_compat_matrix[mode1 + 1][mode2 + 1];
}

/*
 * Compatibility matrix for conversions with QUECVT set.
 * Granted mode is the row; requested mode is the column.
 * Usage: matrix[grmode+1][rqmode+1]
 */

static const int __quecvt_compat_matrix[8][8] = {
      /* UN NL CR CW PR PW EX PD */
        {0, 0, 0, 0, 0, 0, 0, 0},       /* UN */
        {0, 0, 1, 1, 1, 1, 1, 0},       /* NL */
        {0, 0, 0, 1, 1, 1, 1, 0},       /* CR */
        {0, 0, 0, 0, 1, 1, 1, 0},       /* CW */
        {0, 0, 0, 1, 0, 1, 1, 0},       /* PR */
        {0, 0, 0, 0, 0, 0, 1, 0},       /* PW */
        {0, 0, 0, 0, 0, 0, 0, 0},       /* EX */
        {0, 0, 0, 0, 0, 0, 0, 0}        /* PD */
};

void dlm_print_lkb(struct dlm_lkb *lkb)
{
	printk(KERN_ERR "lkb: nodeid %d id %x remid %x exflags %x flags %x "
	       "sts %d rq %d gr %d wait_type %d wait_nodeid %d seq %llu\n",
	       lkb->lkb_nodeid, lkb->lkb_id, lkb->lkb_remid, lkb->lkb_exflags,
	       lkb->lkb_flags, lkb->lkb_status, lkb->lkb_rqmode,
	       lkb->lkb_grmode, lkb->lkb_wait_type, lkb->lkb_wait_nodeid,
	       (unsigned long long)lkb->lkb_recover_seq);
}

static void dlm_print_rsb(struct dlm_rsb *r)
{
	printk(KERN_ERR "rsb: nodeid %d master %d dir %d flags %lx first %x "
	       "rlc %d name %s\n",
	       r->res_nodeid, r->res_master_nodeid, r->res_dir_nodeid,
	       r->res_flags, r->res_first_lkid, r->res_recover_locks_count,
	       r->res_name);
}

void dlm_dump_rsb(struct dlm_rsb *r)
{
	struct dlm_lkb *lkb;

	dlm_print_rsb(r);

	printk(KERN_ERR "rsb: root_list empty %d recover_list empty %d\n",
	       list_empty(&r->res_root_list), list_empty(&r->res_recover_list));
	printk(KERN_ERR "rsb lookup list\n");
	list_for_each_entry(lkb, &r->res_lookup, lkb_rsb_lookup)
		dlm_print_lkb(lkb);
	printk(KERN_ERR "rsb grant queue:\n");
	list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue)
		dlm_print_lkb(lkb);
	printk(KERN_ERR "rsb convert queue:\n");
	list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue)
		dlm_print_lkb(lkb);
	printk(KERN_ERR "rsb wait queue:\n");
	list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue)
		dlm_print_lkb(lkb);
}

/* Threads cannot use the lockspace while it's being recovered */

static inline void dlm_lock_recovery(struct dlm_ls *ls)
{
	down_read(&ls->ls_in_recovery);
}

void dlm_unlock_recovery(struct dlm_ls *ls)
{
	up_read(&ls->ls_in_recovery);
}

int dlm_lock_recovery_try(struct dlm_ls *ls)
{
	return down_read_trylock(&ls->ls_in_recovery);
}

static inline int can_be_queued(struct dlm_lkb *lkb)
{
	return !(lkb->lkb_exflags & DLM_LKF_NOQUEUE);
}

static inline int force_blocking_asts(struct dlm_lkb *lkb)
{
	return (lkb->lkb_exflags & DLM_LKF_NOQUEUEBAST);
}

static inline int is_demoted(struct dlm_lkb *lkb)
{
	return (lkb->lkb_sbflags & DLM_SBF_DEMOTED);
}

static inline int is_altmode(struct dlm_lkb *lkb)
{
	return (lkb->lkb_sbflags & DLM_SBF_ALTMODE);
}

static inline int is_granted(struct dlm_lkb *lkb)
{
	return (lkb->lkb_status == DLM_LKSTS_GRANTED);
}

static inline int is_remote(struct dlm_rsb *r)
{
	DLM_ASSERT(r->res_nodeid >= 0, dlm_print_rsb(r););
	return !!r->res_nodeid;
}

static inline int is_process_copy(struct dlm_lkb *lkb)
{
	return (lkb->lkb_nodeid && !(lkb->lkb_flags & DLM_IFL_MSTCPY));
}

static inline int is_master_copy(struct dlm_lkb *lkb)
{
	return (lkb->lkb_flags & DLM_IFL_MSTCPY) ? 1 : 0;
}

static inline int middle_conversion(struct dlm_lkb *lkb)
{
	if ((lkb->lkb_grmode==DLM_LOCK_PR && lkb->lkb_rqmode==DLM_LOCK_CW) ||
	    (lkb->lkb_rqmode==DLM_LOCK_PR && lkb->lkb_grmode==DLM_LOCK_CW))
		return 1;
	return 0;
}

static inline int down_conversion(struct dlm_lkb *lkb)
{
	return (!middle_conversion(lkb) && lkb->lkb_rqmode < lkb->lkb_grmode);
}

static inline int is_overlap_unlock(struct dlm_lkb *lkb)
{
	return lkb->lkb_flags & DLM_IFL_OVERLAP_UNLOCK;
}

static inline int is_overlap_cancel(struct dlm_lkb *lkb)
{
	return lkb->lkb_flags & DLM_IFL_OVERLAP_CANCEL;
}

static inline int is_overlap(struct dlm_lkb *lkb)
{
	return (lkb->lkb_flags & (DLM_IFL_OVERLAP_UNLOCK |
				  DLM_IFL_OVERLAP_CANCEL));
}

static void queue_cast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
{
	if (is_master_copy(lkb))
		return;

	del_timeout(lkb);

	DLM_ASSERT(lkb->lkb_lksb, dlm_print_lkb(lkb););

	/* if the operation was a cancel, then return -DLM_ECANCEL, if a
	   timeout caused the cancel then return -ETIMEDOUT */
	if (rv == -DLM_ECANCEL && (lkb->lkb_flags & DLM_IFL_TIMEOUT_CANCEL)) {
		lkb->lkb_flags &= ~DLM_IFL_TIMEOUT_CANCEL;
		rv = -ETIMEDOUT;
	}

	if (rv == -DLM_ECANCEL && (lkb->lkb_flags & DLM_IFL_DEADLOCK_CANCEL)) {
		lkb->lkb_flags &= ~DLM_IFL_DEADLOCK_CANCEL;
		rv = -EDEADLK;
	}

	dlm_add_cb(lkb, DLM_CB_CAST, lkb->lkb_grmode, rv, lkb->lkb_sbflags);
}

static inline void queue_cast_overlap(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	queue_cast(r, lkb,
		   is_overlap_unlock(lkb) ? -DLM_EUNLOCK : -DLM_ECANCEL);
}

static void queue_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rqmode)
{
	if (is_master_copy(lkb)) {
		send_bast(r, lkb, rqmode);
	} else {
		dlm_add_cb(lkb, DLM_CB_BAST, rqmode, 0, 0);
	}
}

/*
 * Basic operations on rsb's and lkb's
 */

/* This is only called to add a reference when the code already holds
   a valid reference to the rsb, so there's no need for locking. */

static inline void hold_rsb(struct dlm_rsb *r)
{
	kref_get(&r->res_ref);
}

void dlm_hold_rsb(struct dlm_rsb *r)
{
	hold_rsb(r);
}

/* When all references to the rsb are gone it's transferred to
   the tossed list for later disposal. */

static void put_rsb(struct dlm_rsb *r)
{
	struct dlm_ls *ls = r->res_ls;
	uint32_t bucket = r->res_bucket;

	spin_lock(&ls->ls_rsbtbl[bucket].lock);
	kref_put(&r->res_ref, toss_rsb);
	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
}

void dlm_put_rsb(struct dlm_rsb *r)
{
	put_rsb(r);
}

static int pre_rsb_struct(struct dlm_ls *ls)
{
	struct dlm_rsb *r1, *r2;
	int count = 0;

	spin_lock(&ls->ls_new_rsb_spin);
	if (ls->ls_new_rsb_count > dlm_config.ci_new_rsb_count / 2) {
		spin_unlock(&ls->ls_new_rsb_spin);
		return 0;
	}
	spin_unlock(&ls->ls_new_rsb_spin);

	r1 = dlm_allocate_rsb(ls);
	r2 = dlm_allocate_rsb(ls);

	spin_lock(&ls->ls_new_rsb_spin);
	if (r1) {
		list_add(&r1->res_hashchain, &ls->ls_new_rsb);
		ls->ls_new_rsb_count++;
	}
	if (r2) {
		list_add(&r2->res_hashchain, &ls->ls_new_rsb);
		ls->ls_new_rsb_count++;
	}
	count = ls->ls_new_rsb_count;
	spin_unlock(&ls->ls_new_rsb_spin);

	if (!count)
		return -ENOMEM;
	return 0;
}

/* If ls->ls_new_rsb is empty, return -EAGAIN, so the caller can
   unlock any spinlocks, go back and call pre_rsb_struct again.
   Otherwise, take an rsb off the list and return it. */

static int get_rsb_struct(struct dlm_ls *ls, char *name, int len,
			  struct dlm_rsb **r_ret)
{
	struct dlm_rsb *r;
	int count;

	spin_lock(&ls->ls_new_rsb_spin);
	if (list_empty(&ls->ls_new_rsb)) {
		count = ls->ls_new_rsb_count;
		spin_unlock(&ls->ls_new_rsb_spin);
		log_debug(ls, "find_rsb retry %d %d %s",
			  count, dlm_config.ci_new_rsb_count, name);
		return -EAGAIN;
	}

	r = list_first_entry(&ls->ls_new_rsb, struct dlm_rsb, res_hashchain);
	list_del(&r->res_hashchain);
	/* Convert the empty list_head to a NULL rb_node for tree usage: */
	memset(&r->res_hashnode, 0, sizeof(struct rb_node));
	ls->ls_new_rsb_count--;
	spin_unlock(&ls->ls_new_rsb_spin);

	r->res_ls = ls;
	r->res_length = len;
	memcpy(r->res_name, name, len);
	mutex_init(&r->res_mutex);

	INIT_LIST_HEAD(&r->res_lookup);
	INIT_LIST_HEAD(&r->res_grantqueue);
	INIT_LIST_HEAD(&r->res_convertqueue);
	INIT_LIST_HEAD(&r->res_waitqueue);
	INIT_LIST_HEAD(&r->res_root_list);
	INIT_LIST_HEAD(&r->res_recover_list);

	*r_ret = r;
	return 0;
}

static int rsb_cmp(struct dlm_rsb *r, const char *name, int nlen)
{
	char maxname[DLM_RESNAME_MAXLEN];

	memset(maxname, 0, DLM_RESNAME_MAXLEN);
	memcpy(maxname, name, nlen);
	return memcmp(r->res_name, maxname, DLM_RESNAME_MAXLEN);
}

int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len,
			struct dlm_rsb **r_ret)
{
	struct rb_node *node = tree->rb_node;
	struct dlm_rsb *r;
	int rc;

	while (node) {
		r = rb_entry(node, struct dlm_rsb, res_hashnode);
		rc = rsb_cmp(r, name, len);
		if (rc < 0)
			node = node->rb_left;
		else if (rc > 0)
			node = node->rb_right;
		else
			goto found;
	}
	*r_ret = NULL;
	return -EBADR;

 found:
	*r_ret = r;
	return 0;
}

static int rsb_insert(struct dlm_rsb *rsb, struct rb_root *tree)
{
	struct rb_node **newn = &tree->rb_node;
	struct rb_node *parent = NULL;
	int rc;

	while (*newn) {
		struct dlm_rsb *cur = rb_entry(*newn, struct dlm_rsb,
					       res_hashnode);

		parent = *newn;
		rc = rsb_cmp(cur, rsb->res_name, rsb->res_length);
		if (rc < 0)
			newn = &parent->rb_left;
		else if (rc > 0)
			newn = &parent->rb_right;
		else {
			log_print("rsb_insert match");
			dlm_dump_rsb(rsb);
			dlm_dump_rsb(cur);
			return -EEXIST;
		}
	}

	rb_link_node(&rsb->res_hashnode, parent, newn);
	rb_insert_color(&rsb->res_hashnode, tree);
	return 0;
}

/*
 * Find rsb in rsbtbl and potentially create/add one
 *
 * Delaying the release of rsb's has a similar benefit to applications keeping
 * NL locks on an rsb, but without the guarantee that the cached master value
 * will still be valid when the rsb is reused.  Apps aren't always smart enough
 * to keep NL locks on an rsb that they may lock again shortly; this can lead
 * to excessive master lookups and removals if we don't delay the release.
 *
 * Searching for an rsb means looking through both the normal list and toss
 * list.  When found on the toss list the rsb is moved to the normal list with
 * ref count of 1; when found on normal list the ref count is incremented.
 *
 * rsb's on the keep list are being used locally and refcounted.
 * rsb's on the toss list are not being used locally, and are not refcounted.
 *
 * The toss list rsb's were either
 * - previously used locally but not any more (were on keep list, then
 *   moved to toss list when last refcount dropped)
 * - created and put on toss list as a directory record for a lookup
 *   (we are the dir node for the res, but are not using the res right now,
 *   but some other node is)
 *
 * The purpose of find_rsb() is to return a refcounted rsb for local use.
 * So, if the given rsb is on the toss list, it is moved to the keep list
 * before being returned.
 *
 * toss_rsb() happens when all local usage of the rsb is done, i.e. no
 * more refcounts exist, so the rsb is moved from the keep list to the
 * toss list.
 *
 * rsb's on both keep and toss lists are used for doing a name to master
 * lookups.  rsb's that are in use locally (and being refcounted) are on
 * the keep list, rsb's that are not in use locally (not refcounted) and
 * only exist for name/master lookups are on the toss list.
 *
 * rsb's on the toss list who's dir_nodeid is not local can have stale
 * name/master mappings.  So, remote requests on such rsb's can potentially
 * return with an error, which means the mapping is stale and needs to
 * be updated with a new lookup.  (The idea behind MASTER UNCERTAIN and
 * first_lkid is to keep only a single outstanding request on an rsb
 * while that rsb has a potentially stale master.)
 */

static int find_rsb_dir(struct dlm_ls *ls, char *name, int len,
			uint32_t hash, uint32_t b,
			int dir_nodeid, int from_nodeid,
			unsigned int flags, struct dlm_rsb **r_ret)
{
	struct dlm_rsb *r = NULL;
	int our_nodeid = dlm_our_nodeid();
	int from_local = 0;
	int from_other = 0;
	int from_dir = 0;
	int create = 0;
	int error;

	if (flags & R_RECEIVE_REQUEST) {
		if (from_nodeid == dir_nodeid)
			from_dir = 1;
		else
			from_other = 1;
	} else if (flags & R_REQUEST) {
		from_local = 1;
	}

	/*
	 * flags & R_RECEIVE_RECOVER is from dlm_recover_master_copy, so
	 * from_nodeid has sent us a lock in dlm_recover_locks, believing
	 * we're the new master.  Our local recovery may not have set
	 * res_master_nodeid to our_nodeid yet, so allow either.  Don't
	 * create the rsb; dlm_recover_process_copy() will handle EBADR
	 * by resending.
	 *
	 * If someone sends us a request, we are the dir node, and we do
	 * not find the rsb anywhere, then recreate it.  This happens if
	 * someone sends us a request after we have removed/freed an rsb
	 * from our toss list.  (They sent a request instead of lookup
	 * because they are using an rsb from their toss list.)
	 */

	if (from_local || from_dir ||
	    (from_other && (dir_nodeid == our_nodeid))) {
		create = 1;
	}

 retry:
	if (create) {
		error = pre_rsb_struct(ls);
		if (error < 0)
			goto out;
	}

	spin_lock(&ls->ls_rsbtbl[b].lock);

	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
	if (error)
		goto do_toss;
	
	/*
	 * rsb is active, so we can't check master_nodeid without lock_rsb.
	 */

	kref_get(&r->res_ref);
	error = 0;
	goto out_unlock;


 do_toss:
	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
	if (error)
		goto do_new;

	/*
	 * rsb found inactive (master_nodeid may be out of date unless
	 * we are the dir_nodeid or were the master)  No other thread
	 * is using this rsb because it's on the toss list, so we can
	 * look at or update res_master_nodeid without lock_rsb.
	 */

	if ((r->res_master_nodeid != our_nodeid) && from_other) {
		/* our rsb was not master, and another node (not the dir node)
		   has sent us a request */
		log_debug(ls, "find_rsb toss from_other %d master %d dir %d %s",
			  from_nodeid, r->res_master_nodeid, dir_nodeid,
			  r->res_name);
		error = -ENOTBLK;
		goto out_unlock;
	}

	if ((r->res_master_nodeid != our_nodeid) && from_dir) {
		/* don't think this should ever happen */
		log_error(ls, "find_rsb toss from_dir %d master %d",
			  from_nodeid, r->res_master_nodeid);
		dlm_print_rsb(r);
		/* fix it and go on */
		r->res_master_nodeid = our_nodeid;
		r->res_nodeid = 0;
		rsb_clear_flag(r, RSB_MASTER_UNCERTAIN);
		r->res_first_lkid = 0;
	}

	if (from_local && (r->res_master_nodeid != our_nodeid)) {
		/* Because we have held no locks on this rsb,
		   res_master_nodeid could have become stale. */
		rsb_set_flag(r, RSB_MASTER_UNCERTAIN);
		r->res_first_lkid = 0;
	}

	rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
	goto out_unlock;


 do_new:
	/*
	 * rsb not found
	 */

	if (error == -EBADR && !create)
		goto out_unlock;

	error = get_rsb_struct(ls, name, len, &r);
	if (error == -EAGAIN) {
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		goto retry;
	}
	if (error)
		goto out_unlock;

	r->res_hash = hash;
	r->res_bucket = b;
	r->res_dir_nodeid = dir_nodeid;
	kref_init(&r->res_ref);

	if (from_dir) {
		/* want to see how often this happens */
		log_debug(ls, "find_rsb new from_dir %d recreate %s",
			  from_nodeid, r->res_name);
		r->res_master_nodeid = our_nodeid;
		r->res_nodeid = 0;
		goto out_add;
	}

	if (from_other && (dir_nodeid != our_nodeid)) {
		/* should never happen */
		log_error(ls, "find_rsb new from_other %d dir %d our %d %s",
			  from_nodeid, dir_nodeid, our_nodeid, r->res_name);
		dlm_free_rsb(r);
		r = NULL;
		error = -ENOTBLK;
		goto out_unlock;
	}

	if (from_other) {
		log_debug(ls, "find_rsb new from_other %d dir %d %s",
			  from_nodeid, dir_nodeid, r->res_name);
	}

	if (dir_nodeid == our_nodeid) {
		/* When we are the dir nodeid, we can set the master
		   node immediately */
		r->res_master_nodeid = our_nodeid;
		r->res_nodeid = 0;
	} else {
		/* set_master will send_lookup to dir_nodeid */
		r->res_master_nodeid = 0;
		r->res_nodeid = -1;
	}

 out_add:
	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
 out_unlock:
	spin_unlock(&ls->ls_rsbtbl[b].lock);
 out:
	*r_ret = r;
	return error;
}

/* During recovery, other nodes can send us new MSTCPY locks (from
   dlm_recover_locks) before we've made ourself master (in
   dlm_recover_masters). */

static int find_rsb_nodir(struct dlm_ls *ls, char *name, int len,
			  uint32_t hash, uint32_t b,
			  int dir_nodeid, int from_nodeid,
			  unsigned int flags, struct dlm_rsb **r_ret)
{
	struct dlm_rsb *r = NULL;
	int our_nodeid = dlm_our_nodeid();
	int recover = (flags & R_RECEIVE_RECOVER);
	int error;

 retry:
	error = pre_rsb_struct(ls);
	if (error < 0)
		goto out;

	spin_lock(&ls->ls_rsbtbl[b].lock);

	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
	if (error)
		goto do_toss;

	/*
	 * rsb is active, so we can't check master_nodeid without lock_rsb.
	 */

	kref_get(&r->res_ref);
	goto out_unlock;


 do_toss:
	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
	if (error)
		goto do_new;

	/*
	 * rsb found inactive. No other thread is using this rsb because
	 * it's on the toss list, so we can look at or update
	 * res_master_nodeid without lock_rsb.
	 */

	if (!recover && (r->res_master_nodeid != our_nodeid) && from_nodeid) {
		/* our rsb is not master, and another node has sent us a
		   request; this should never happen */
		log_error(ls, "find_rsb toss from_nodeid %d master %d dir %d",
			  from_nodeid, r->res_master_nodeid, dir_nodeid);
		dlm_print_rsb(r);
		error = -ENOTBLK;
		goto out_unlock;
	}

	if (!recover && (r->res_master_nodeid != our_nodeid) &&
	    (dir_nodeid == our_nodeid)) {
		/* our rsb is not master, and we are dir; may as well fix it;
		   this should never happen */
		log_error(ls, "find_rsb toss our %d master %d dir %d",
			  our_nodeid, r->res_master_nodeid, dir_nodeid);
		dlm_print_rsb(r);
		r->res_master_nodeid = our_nodeid;
		r->res_nodeid = 0;
	}

	rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
	goto out_unlock;


 do_new:
	/*
	 * rsb not found
	 */

	error = get_rsb_struct(ls, name, len, &r);
	if (error == -EAGAIN) {
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		goto retry;
	}
	if (error)
		goto out_unlock;

	r->res_hash = hash;
	r->res_bucket = b;
	r->res_dir_nodeid = dir_nodeid;
	r->res_master_nodeid = dir_nodeid;
	r->res_nodeid = (dir_nodeid == our_nodeid) ? 0 : dir_nodeid;
	kref_init(&r->res_ref);

	error = rsb_insert(r, &ls->ls_rsbtbl[b].keep);
 out_unlock:
	spin_unlock(&ls->ls_rsbtbl[b].lock);
 out:
	*r_ret = r;
	return error;
}

static int find_rsb(struct dlm_ls *ls, char *name, int len, int from_nodeid,
		    unsigned int flags, struct dlm_rsb **r_ret)
{
	uint32_t hash, b;
	int dir_nodeid;

	if (len > DLM_RESNAME_MAXLEN)
		return -EINVAL;

	hash = jhash(name, len, 0);
	b = hash & (ls->ls_rsbtbl_size - 1);

	dir_nodeid = dlm_hash2nodeid(ls, hash);

	if (dlm_no_directory(ls))
		return find_rsb_nodir(ls, name, len, hash, b, dir_nodeid,
				      from_nodeid, flags, r_ret);
	else
		return find_rsb_dir(ls, name, len, hash, b, dir_nodeid,
				      from_nodeid, flags, r_ret);
}

/* we have received a request and found that res_master_nodeid != our_nodeid,
   so we need to return an error or make ourself the master */

static int validate_master_nodeid(struct dlm_ls *ls, struct dlm_rsb *r,
				  int from_nodeid)
{
	if (dlm_no_directory(ls)) {
		log_error(ls, "find_rsb keep from_nodeid %d master %d dir %d",
			  from_nodeid, r->res_master_nodeid,
			  r->res_dir_nodeid);
		dlm_print_rsb(r);
		return -ENOTBLK;
	}

	if (from_nodeid != r->res_dir_nodeid) {
		/* our rsb is not master, and another node (not the dir node)
	   	   has sent us a request.  this is much more common when our
	   	   master_nodeid is zero, so limit debug to non-zero.  */

		if (r->res_master_nodeid) {
			log_debug(ls, "validate master from_other %d master %d "
				  "dir %d first %x %s", from_nodeid,
				  r->res_master_nodeid, r->res_dir_nodeid,
				  r->res_first_lkid, r->res_name);
		}
		return -ENOTBLK;
	} else {
		/* our rsb is not master, but the dir nodeid has sent us a
	   	   request; this could happen with master 0 / res_nodeid -1 */

		if (r->res_master_nodeid) {
			log_error(ls, "validate master from_dir %d master %d "
				  "first %x %s",
				  from_nodeid, r->res_master_nodeid,
				  r->res_first_lkid, r->res_name);
		}

		r->res_master_nodeid = dlm_our_nodeid();
		r->res_nodeid = 0;
		return 0;
	}
}

/*
 * We're the dir node for this res and another node wants to know the
 * master nodeid.  During normal operation (non recovery) this is only
 * called from receive_lookup(); master lookups when the local node is
 * the dir node are done by find_rsb().
 *
 * normal operation, we are the dir node for a resource
 * . _request_lock
 * . set_master
 * . send_lookup
 * . receive_lookup
 * . dlm_master_lookup flags 0
 *
 * recover directory, we are rebuilding dir for all resources
 * . dlm_recover_directory
 * . dlm_rcom_names
 *   remote node sends back the rsb names it is master of and we are dir of
 * . dlm_master_lookup RECOVER_DIR (fix_master 0, from_master 1)
 *   we either create new rsb setting remote node as master, or find existing
 *   rsb and set master to be the remote node.
 *
 * recover masters, we are finding the new master for resources
 * . dlm_recover_masters
 * . recover_master
 * . dlm_send_rcom_lookup
 * . receive_rcom_lookup
 * . dlm_master_lookup RECOVER_MASTER (fix_master 1, from_master 0)
 */

int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, char *name, int len,
		      unsigned int flags, int *r_nodeid, int *result)
{
	struct dlm_rsb *r = NULL;
	uint32_t hash, b;
	int from_master = (flags & DLM_LU_RECOVER_DIR);
	int fix_master = (flags & DLM_LU_RECOVER_MASTER);
	int our_nodeid = dlm_our_nodeid();
	int dir_nodeid, error, toss_list = 0;

	if (len > DLM_RESNAME_MAXLEN)
		return -EINVAL;

	if (from_nodeid == our_nodeid) {
		log_error(ls, "dlm_master_lookup from our_nodeid %d flags %x",
			  our_nodeid, flags);
		return -EINVAL;
	}

	hash = jhash(name, len, 0);
	b = hash & (ls->ls_rsbtbl_size - 1);

	dir_nodeid = dlm_hash2nodeid(ls, hash);
	if (dir_nodeid != our_nodeid) {
		log_error(ls, "dlm_master_lookup from %d dir %d our %d h %x %d",
			  from_nodeid, dir_nodeid, our_nodeid, hash,
			  ls->ls_num_nodes);
		*r_nodeid = -1;
		return -EINVAL;
	}

 retry:
	error = pre_rsb_struct(ls);
	if (error < 0)
		return error;

	spin_lock(&ls->ls_rsbtbl[b].lock);
	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
	if (!error) {
		/* because the rsb is active, we need to lock_rsb before
		   checking/changing re_master_nodeid */

		hold_rsb(r);
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		lock_rsb(r);
		goto found;
	}

	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
	if (error)
		goto not_found;

	/* because the rsb is inactive (on toss list), it's not refcounted
	   and lock_rsb is not used, but is protected by the rsbtbl lock */

	toss_list = 1;
 found:
	if (r->res_dir_nodeid != our_nodeid) {
		/* should not happen, but may as well fix it and carry on */
		log_error(ls, "dlm_master_lookup res_dir %d our %d %s",
			  r->res_dir_nodeid, our_nodeid, r->res_name);
		r->res_dir_nodeid = our_nodeid;
	}

	if (fix_master && dlm_is_removed(ls, r->res_master_nodeid)) {
		/* Recovery uses this function to set a new master when
		   the previous master failed.  Setting NEW_MASTER will
		   force dlm_recover_masters to call recover_master on this
		   rsb even though the res_nodeid is no longer removed. */

		r->res_master_nodeid = from_nodeid;
		r->res_nodeid = from_nodeid;
		rsb_set_flag(r, RSB_NEW_MASTER);

		if (toss_list) {
			/* I don't think we should ever find it on toss list. */
			log_error(ls, "dlm_master_lookup fix_master on toss");
			dlm_dump_rsb(r);
		}
	}

	if (from_master && (r->res_master_nodeid != from_nodeid)) {
		/* this will happen if from_nodeid became master during
		   a previous recovery cycle, and we aborted the previous
		   cycle before recovering this master value */

		log_limit(ls, "dlm_master_lookup from_master %d "
			  "master_nodeid %d res_nodeid %d first %x %s",
			  from_nodeid, r->res_master_nodeid, r->res_nodeid,
			  r->res_first_lkid, r->res_name);

		if (r->res_master_nodeid == our_nodeid) {
			log_error(ls, "from_master %d our_master", from_nodeid);
			dlm_dump_rsb(r);
			goto out_found;
		}

		r->res_master_nodeid = from_nodeid;
		r->res_nodeid = from_nodeid;
		rsb_set_flag(r, RSB_NEW_MASTER);
	}

	if (!r->res_master_nodeid) {
		/* this will happen if recovery happens while we're looking
		   up the master for this rsb */

		log_debug(ls, "dlm_master_lookup master 0 to %d first %x %s",
			  from_nodeid, r->res_first_lkid, r->res_name);
		r->res_master_nodeid = from_nodeid;
		r->res_nodeid = from_nodeid;
	}

	if (!from_master && !fix_master &&
	    (r->res_master_nodeid == from_nodeid)) {
		/* this can happen when the master sends remove, the dir node
		   finds the rsb on the keep list and ignores the remove,
		   and the former master sends a lookup */

		log_limit(ls, "dlm_master_lookup from master %d flags %x "
			  "first %x %s", from_nodeid, flags,
			  r->res_first_lkid, r->res_name);
	}

 out_found:
	*r_nodeid = r->res_master_nodeid;
	if (result)
		*result = DLM_LU_MATCH;

	if (toss_list) {
		r->res_toss_time = jiffies;
		/* the rsb was inactive (on toss list) */
		spin_unlock(&ls->ls_rsbtbl[b].lock);
	} else {
		/* the rsb was active */
		unlock_rsb(r);
		put_rsb(r);
	}
	return 0;

 not_found:
	error = get_rsb_struct(ls, name, len, &r);
	if (error == -EAGAIN) {
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		goto retry;
	}
	if (error)
		goto out_unlock;

	r->res_hash = hash;
	r->res_bucket = b;
	r->res_dir_nodeid = our_nodeid;
	r->res_master_nodeid = from_nodeid;
	r->res_nodeid = from_nodeid;
	kref_init(&r->res_ref);
	r->res_toss_time = jiffies;

	error = rsb_insert(r, &ls->ls_rsbtbl[b].toss);
	if (error) {
		/* should never happen */
		dlm_free_rsb(r);
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		goto retry;
	}

	if (result)
		*result = DLM_LU_ADD;
	*r_nodeid = from_nodeid;
	error = 0;
 out_unlock:
	spin_unlock(&ls->ls_rsbtbl[b].lock);
	return error;
}

static void dlm_dump_rsb_hash(struct dlm_ls *ls, uint32_t hash)
{
	struct rb_node *n;
	struct dlm_rsb *r;
	int i;

	for (i = 0; i < ls->ls_rsbtbl_size; i++) {
		spin_lock(&ls->ls_rsbtbl[i].lock);
		for (n = rb_first(&ls->ls_rsbtbl[i].keep); n; n = rb_next(n)) {
			r = rb_entry(n, struct dlm_rsb, res_hashnode);
			if (r->res_hash == hash)
				dlm_dump_rsb(r);
		}
		spin_unlock(&ls->ls_rsbtbl[i].lock);
	}
}

void dlm_dump_rsb_name(struct dlm_ls *ls, char *name, int len)
{
	struct dlm_rsb *r = NULL;
	uint32_t hash, b;
	int error;

	hash = jhash(name, len, 0);
	b = hash & (ls->ls_rsbtbl_size - 1);

	spin_lock(&ls->ls_rsbtbl[b].lock);
	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
	if (!error)
		goto out_dump;

	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
	if (error)
		goto out;
 out_dump:
	dlm_dump_rsb(r);
 out:
	spin_unlock(&ls->ls_rsbtbl[b].lock);
}

static void toss_rsb(struct kref *kref)
{
	struct dlm_rsb *r = container_of(kref, struct dlm_rsb, res_ref);
	struct dlm_ls *ls = r->res_ls;

	DLM_ASSERT(list_empty(&r->res_root_list), dlm_print_rsb(r););
	kref_init(&r->res_ref);
	rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[r->res_bucket].keep);
	rsb_insert(r, &ls->ls_rsbtbl[r->res_bucket].toss);
	r->res_toss_time = jiffies;
	ls->ls_rsbtbl[r->res_bucket].flags |= DLM_RTF_SHRINK;
	if (r->res_lvbptr) {
		dlm_free_lvb(r->res_lvbptr);
		r->res_lvbptr = NULL;
	}
}

/* See comment for unhold_lkb */

static void unhold_rsb(struct dlm_rsb *r)
{
	int rv;
	rv = kref_put(&r->res_ref, toss_rsb);
	DLM_ASSERT(!rv, dlm_dump_rsb(r););
}

static void kill_rsb(struct kref *kref)
{
	struct dlm_rsb *r = container_of(kref, struct dlm_rsb, res_ref);

	/* All work is done after the return from kref_put() so we
	   can release the write_lock before the remove and free. */

	DLM_ASSERT(list_empty(&r->res_lookup), dlm_dump_rsb(r););
	DLM_ASSERT(list_empty(&r->res_grantqueue), dlm_dump_rsb(r););
	DLM_ASSERT(list_empty(&r->res_convertqueue), dlm_dump_rsb(r););
	DLM_ASSERT(list_empty(&r->res_waitqueue), dlm_dump_rsb(r););
	DLM_ASSERT(list_empty(&r->res_root_list), dlm_dump_rsb(r););
	DLM_ASSERT(list_empty(&r->res_recover_list), dlm_dump_rsb(r););
}

/* Attaching/detaching lkb's from rsb's is for rsb reference counting.
   The rsb must exist as long as any lkb's for it do. */

static void attach_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	hold_rsb(r);
	lkb->lkb_resource = r;
}

static void detach_lkb(struct dlm_lkb *lkb)
{
	if (lkb->lkb_resource) {
		put_rsb(lkb->lkb_resource);
		lkb->lkb_resource = NULL;
	}
}

static int create_lkb(struct dlm_ls *ls, struct dlm_lkb **lkb_ret)
{
	struct dlm_lkb *lkb;
	int rv;

	lkb = dlm_allocate_lkb(ls);
	if (!lkb)
		return -ENOMEM;

	lkb->lkb_nodeid = -1;
	lkb->lkb_grmode = DLM_LOCK_IV;
	kref_init(&lkb->lkb_ref);
	INIT_LIST_HEAD(&lkb->lkb_ownqueue);
	INIT_LIST_HEAD(&lkb->lkb_rsb_lookup);
	INIT_LIST_HEAD(&lkb->lkb_time_list);
	INIT_LIST_HEAD(&lkb->lkb_cb_list);
	mutex_init(&lkb->lkb_cb_mutex);
	INIT_WORK(&lkb->lkb_cb_work, dlm_callback_work);

	idr_preload(GFP_NOFS);
	spin_lock(&ls->ls_lkbidr_spin);
	rv = idr_alloc(&ls->ls_lkbidr, lkb, 1, 0, GFP_NOWAIT);
	if (rv >= 0)
		lkb->lkb_id = rv;
	spin_unlock(&ls->ls_lkbidr_spin);
	idr_preload_end();

	if (rv < 0) {
		log_error(ls, "create_lkb idr error %d", rv);
		dlm_free_lkb(lkb);
		return rv;
	}

	*lkb_ret = lkb;
	return 0;
}

static int find_lkb(struct dlm_ls *ls, uint32_t lkid, struct dlm_lkb **lkb_ret)
{
	struct dlm_lkb *lkb;

	spin_lock(&ls->ls_lkbidr_spin);
	lkb = idr_find(&ls->ls_lkbidr, lkid);
	if (lkb)
		kref_get(&lkb->lkb_ref);
	spin_unlock(&ls->ls_lkbidr_spin);

	*lkb_ret = lkb;
	return lkb ? 0 : -ENOENT;
}

static void kill_lkb(struct kref *kref)
{
	struct dlm_lkb *lkb = container_of(kref, struct dlm_lkb, lkb_ref);

	/* All work is done after the return from kref_put() so we
	   can release the write_lock before the detach_lkb */

	DLM_ASSERT(!lkb->lkb_status, dlm_print_lkb(lkb););
}

/* __put_lkb() is used when an lkb may not have an rsb attached to
   it so we need to provide the lockspace explicitly */

static int __put_lkb(struct dlm_ls *ls, struct dlm_lkb *lkb)
{
	uint32_t lkid = lkb->lkb_id;

	spin_lock(&ls->ls_lkbidr_spin);
	if (kref_put(&lkb->lkb_ref, kill_lkb)) {
		idr_remove(&ls->ls_lkbidr, lkid);
		spin_unlock(&ls->ls_lkbidr_spin);

		detach_lkb(lkb);

		/* for local/process lkbs, lvbptr points to caller's lksb */
		if (lkb->lkb_lvbptr && is_master_copy(lkb))
			dlm_free_lvb(lkb->lkb_lvbptr);
		dlm_free_lkb(lkb);
		return 1;
	} else {
		spin_unlock(&ls->ls_lkbidr_spin);
		return 0;
	}
}

int dlm_put_lkb(struct dlm_lkb *lkb)
{
	struct dlm_ls *ls;

	DLM_ASSERT(lkb->lkb_resource, dlm_print_lkb(lkb););
	DLM_ASSERT(lkb->lkb_resource->res_ls, dlm_print_lkb(lkb););

	ls = lkb->lkb_resource->res_ls;
	return __put_lkb(ls, lkb);
}

/* This is only called to add a reference when the code already holds
   a valid reference to the lkb, so there's no need for locking. */

static inline void hold_lkb(struct dlm_lkb *lkb)
{
	kref_get(&lkb->lkb_ref);
}

/* This is called when we need to remove a reference and are certain
   it's not the last ref.  e.g. del_lkb is always called between a
   find_lkb/put_lkb and is always the inverse of a previous add_lkb.
   put_lkb would work fine, but would involve unnecessary locking */

static inline void unhold_lkb(struct dlm_lkb *lkb)
{
	int rv;
	rv = kref_put(&lkb->lkb_ref, kill_lkb);
	DLM_ASSERT(!rv, dlm_print_lkb(lkb););
}

static void lkb_add_ordered(struct list_head *new, struct list_head *head,
			    int mode)
{
	struct dlm_lkb *lkb = NULL;

	list_for_each_entry(lkb, head, lkb_statequeue)
		if (lkb->lkb_rqmode < mode)
			break;

	__list_add(new, lkb->lkb_statequeue.prev, &lkb->lkb_statequeue);
}

/* add/remove lkb to rsb's grant/convert/wait queue */

static void add_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb, int status)
{
	kref_get(&lkb->lkb_ref);

	DLM_ASSERT(!lkb->lkb_status, dlm_print_lkb(lkb););

	lkb->lkb_timestamp = ktime_get();

	lkb->lkb_status = status;

	switch (status) {
	case DLM_LKSTS_WAITING:
		if (lkb->lkb_exflags & DLM_LKF_HEADQUE)
			list_add(&lkb->lkb_statequeue, &r->res_waitqueue);
		else
			list_add_tail(&lkb->lkb_statequeue, &r->res_waitqueue);
		break;
	case DLM_LKSTS_GRANTED:
		/* convention says granted locks kept in order of grmode */
		lkb_add_ordered(&lkb->lkb_statequeue, &r->res_grantqueue,
				lkb->lkb_grmode);
		break;
	case DLM_LKSTS_CONVERT:
		if (lkb->lkb_exflags & DLM_LKF_HEADQUE)
			list_add(&lkb->lkb_statequeue, &r->res_convertqueue);
		else
			list_add_tail(&lkb->lkb_statequeue,
				      &r->res_convertqueue);
		break;
	default:
		DLM_ASSERT(0, dlm_print_lkb(lkb); printk("sts=%d\n", status););
	}
}

static void del_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	lkb->lkb_status = 0;
	list_del(&lkb->lkb_statequeue);
	unhold_lkb(lkb);
}

static void move_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb, int sts)
{
	hold_lkb(lkb);
	del_lkb(r, lkb);
	add_lkb(r, lkb, sts);
	unhold_lkb(lkb);
}

static int msg_reply_type(int mstype)
{
	switch (mstype) {
	case DLM_MSG_REQUEST:
		return DLM_MSG_REQUEST_REPLY;
	case DLM_MSG_CONVERT:
		return DLM_MSG_CONVERT_REPLY;
	case DLM_MSG_UNLOCK:
		return DLM_MSG_UNLOCK_REPLY;
	case DLM_MSG_CANCEL:
		return DLM_MSG_CANCEL_REPLY;
	case DLM_MSG_LOOKUP:
		return DLM_MSG_LOOKUP_REPLY;
	}
	return -1;
}

static int nodeid_warned(int nodeid, int num_nodes, int *warned)
{
	int i;

	for (i = 0; i < num_nodes; i++) {
		if (!warned[i]) {
			warned[i] = nodeid;
			return 0;
		}
		if (warned[i] == nodeid)
			return 1;
	}
	return 0;
}

void dlm_scan_waiters(struct dlm_ls *ls)
{
	struct dlm_lkb *lkb;
	s64 us;
	s64 debug_maxus = 0;
	u32 debug_scanned = 0;
	u32 debug_expired = 0;
	int num_nodes = 0;
	int *warned = NULL;

	if (!dlm_config.ci_waitwarn_us)
		return;

	mutex_lock(&ls->ls_waiters_mutex);

	list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
		if (!lkb->lkb_wait_time)
			continue;

		debug_scanned++;

		us = ktime_to_us(ktime_sub(ktime_get(), lkb->lkb_wait_time));

		if (us < dlm_config.ci_waitwarn_us)
			continue;

		lkb->lkb_wait_time = 0;

		debug_expired++;
		if (us > debug_maxus)
			debug_maxus = us;

		if (!num_nodes) {
			num_nodes = ls->ls_num_nodes;
			warned = kcalloc(num_nodes, sizeof(int), GFP_KERNEL);
		}
		if (!warned)
			continue;
		if (nodeid_warned(lkb->lkb_wait_nodeid, num_nodes, warned))
			continue;

		log_error(ls, "waitwarn %x %lld %d us check connection to "
			  "node %d", lkb->lkb_id, (long long)us,
			  dlm_config.ci_waitwarn_us, lkb->lkb_wait_nodeid);
	}
	mutex_unlock(&ls->ls_waiters_mutex);
	kfree(warned);

	if (debug_expired)
		log_debug(ls, "scan_waiters %u warn %u over %d us max %lld us",
			  debug_scanned, debug_expired,
			  dlm_config.ci_waitwarn_us, (long long)debug_maxus);
}

/* add/remove lkb from global waiters list of lkb's waiting for
   a reply from a remote node */

static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
	int error = 0;

	mutex_lock(&ls->ls_waiters_mutex);

	if (is_overlap_unlock(lkb) ||
	    (is_overlap_cancel(lkb) && (mstype == DLM_MSG_CANCEL))) {
		error = -EINVAL;
		goto out;
	}

	if (lkb->lkb_wait_type || is_overlap_cancel(lkb)) {
		switch (mstype) {
		case DLM_MSG_UNLOCK:
			lkb->lkb_flags |= DLM_IFL_OVERLAP_UNLOCK;
			break;
		case DLM_MSG_CANCEL:
			lkb->lkb_flags |= DLM_IFL_OVERLAP_CANCEL;
			break;
		default:
			error = -EBUSY;
			goto out;
		}
		lkb->lkb_wait_count++;
		hold_lkb(lkb);

		log_debug(ls, "addwait %x cur %d overlap %d count %d f %x",
			  lkb->lkb_id, lkb->lkb_wait_type, mstype,
			  lkb->lkb_wait_count, lkb->lkb_flags);
		goto out;
	}

	DLM_ASSERT(!lkb->lkb_wait_count,
		   dlm_print_lkb(lkb);
		   printk("wait_count %d\n", lkb->lkb_wait_count););

	lkb->lkb_wait_count++;
	lkb->lkb_wait_type = mstype;
	lkb->lkb_wait_time = ktime_get();
	lkb->lkb_wait_nodeid = to_nodeid; /* for debugging */
	hold_lkb(lkb);
	list_add(&lkb->lkb_wait_reply, &ls->ls_waiters);
 out:
	if (error)
		log_error(ls, "addwait error %x %d flags %x %d %d %s",
			  lkb->lkb_id, error, lkb->lkb_flags, mstype,
			  lkb->lkb_wait_type, lkb->lkb_resource->res_name);
	mutex_unlock(&ls->ls_waiters_mutex);
	return error;
}

/* We clear the RESEND flag because we might be taking an lkb off the waiters
   list as part of process_requestqueue (e.g. a lookup that has an optimized
   request reply on the requestqueue) between dlm_recover_waiters_pre() which
   set RESEND and dlm_recover_waiters_post() */

static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype,
				struct dlm_message *ms)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
	int overlap_done = 0;

	if (is_overlap_unlock(lkb) && (mstype == DLM_MSG_UNLOCK_REPLY)) {
		log_debug(ls, "remwait %x unlock_reply overlap", lkb->lkb_id);
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
		overlap_done = 1;
		goto out_del;
	}

	if (is_overlap_cancel(lkb) && (mstype == DLM_MSG_CANCEL_REPLY)) {
		log_debug(ls, "remwait %x cancel_reply overlap", lkb->lkb_id);
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
		overlap_done = 1;
		goto out_del;
	}

	/* Cancel state was preemptively cleared by a successful convert,
	   see next comment, nothing to do. */

	if ((mstype == DLM_MSG_CANCEL_REPLY) &&
	    (lkb->lkb_wait_type != DLM_MSG_CANCEL)) {
		log_debug(ls, "remwait %x cancel_reply wait_type %d",
			  lkb->lkb_id, lkb->lkb_wait_type);
		return -1;
	}

	/* Remove for the convert reply, and premptively remove for the
	   cancel reply.  A convert has been granted while there's still
	   an outstanding cancel on it (the cancel is moot and the result
	   in the cancel reply should be 0).  We preempt the cancel reply
	   because the app gets the convert result and then can follow up
	   with another op, like convert.  This subsequent op would see the
	   lingering state of the cancel and fail with -EBUSY. */

	if ((mstype == DLM_MSG_CONVERT_REPLY) &&
	    (lkb->lkb_wait_type == DLM_MSG_CONVERT) &&
	    is_overlap_cancel(lkb) && ms && !ms->m_result) {
		log_debug(ls, "remwait %x convert_reply zap overlap_cancel",
			  lkb->lkb_id);
		lkb->lkb_wait_type = 0;
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
		lkb->lkb_wait_count--;
		goto out_del;
	}

	/* N.B. type of reply may not always correspond to type of original
	   msg due to lookup->request optimization, verify others? */

	if (lkb->lkb_wait_type) {
		lkb->lkb_wait_type = 0;
		goto out_del;
	}

	log_error(ls, "remwait error %x remote %d %x msg %d flags %x no wait",
		  lkb->lkb_id, ms ? ms->m_header.h_nodeid : 0, lkb->lkb_remid,
		  mstype, lkb->lkb_flags);
	return -1;

 out_del:
	/* the force-unlock/cancel has completed and we haven't recvd a reply
	   to the op that was in progress prior to the unlock/cancel; we
	   give up on any reply to the earlier op.  FIXME: not sure when/how
	   this would happen */

	if (overlap_done && lkb->lkb_wait_type) {
		log_error(ls, "remwait error %x reply %d wait_type %d overlap",
			  lkb->lkb_id, mstype, lkb->lkb_wait_type);
		lkb->lkb_wait_count--;
		lkb->lkb_wait_type = 0;
	}

	DLM_ASSERT(lkb->lkb_wait_count, dlm_print_lkb(lkb););

	lkb->lkb_flags &= ~DLM_IFL_RESEND;
	lkb->lkb_wait_count--;
	if (!lkb->lkb_wait_count)
		list_del_init(&lkb->lkb_wait_reply);
	unhold_lkb(lkb);
	return 0;
}

static int remove_from_waiters(struct dlm_lkb *lkb, int mstype)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
	int error;

	mutex_lock(&ls->ls_waiters_mutex);
	error = _remove_from_waiters(lkb, mstype, NULL);
	mutex_unlock(&ls->ls_waiters_mutex);
	return error;
}

/* Handles situations where we might be processing a "fake" or "stub" reply in
   which we can't try to take waiters_mutex again. */

static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
	int error;

	if (ms->m_flags != DLM_IFL_STUB_MS)
		mutex_lock(&ls->ls_waiters_mutex);
	error = _remove_from_waiters(lkb, ms->m_type, ms);
	if (ms->m_flags != DLM_IFL_STUB_MS)
		mutex_unlock(&ls->ls_waiters_mutex);
	return error;
}

/* If there's an rsb for the same resource being removed, ensure
   that the remove message is sent before the new lookup message.
   It should be rare to need a delay here, but if not, then it may
   be worthwhile to add a proper wait mechanism rather than a delay. */

static void wait_pending_remove(struct dlm_rsb *r)
{
	struct dlm_ls *ls = r->res_ls;
 restart:
	spin_lock(&ls->ls_remove_spin);
	if (ls->ls_remove_len &&
	    !rsb_cmp(r, ls->ls_remove_name, ls->ls_remove_len)) {
		log_debug(ls, "delay lookup for remove dir %d %s",
		  	  r->res_dir_nodeid, r->res_name);
		spin_unlock(&ls->ls_remove_spin);
		msleep(1);
		goto restart;
	}
	spin_unlock(&ls->ls_remove_spin);
}

/*
 * ls_remove_spin protects ls_remove_name and ls_remove_len which are
 * read by other threads in wait_pending_remove.  ls_remove_names
 * and ls_remove_lens are only used by the scan thread, so they do
 * not need protection.
 */

static void shrink_bucket(struct dlm_ls *ls, int b)
{
	struct rb_node *n, *next;
	struct dlm_rsb *r;
	char *name;
	int our_nodeid = dlm_our_nodeid();
	int remote_count = 0;
	int need_shrink = 0;
	int i, len, rv;

	memset(&ls->ls_remove_lens, 0, sizeof(int) * DLM_REMOVE_NAMES_MAX);

	spin_lock(&ls->ls_rsbtbl[b].lock);

	if (!(ls->ls_rsbtbl[b].flags & DLM_RTF_SHRINK)) {
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		return;
	}

	for (n = rb_first(&ls->ls_rsbtbl[b].toss); n; n = next) {
		next = rb_next(n);
		r = rb_entry(n, struct dlm_rsb, res_hashnode);

		/* If we're the directory record for this rsb, and
		   we're not the master of it, then we need to wait
		   for the master node to send us a dir remove for
		   before removing the dir record. */

		if (!dlm_no_directory(ls) &&
		    (r->res_master_nodeid != our_nodeid) &&
		    (dlm_dir_nodeid(r) == our_nodeid)) {
			continue;
		}

		need_shrink = 1;

		if (!time_after_eq(jiffies, r->res_toss_time +
				   dlm_config.ci_toss_secs * HZ)) {
			continue;
		}

		if (!dlm_no_directory(ls) &&
		    (r->res_master_nodeid == our_nodeid) &&
		    (dlm_dir_nodeid(r) != our_nodeid)) {

			/* We're the master of this rsb but we're not
			   the directory record, so we need to tell the
			   dir node to remove the dir record. */

			ls->ls_remove_lens[remote_count] = r->res_length;
			memcpy(ls->ls_remove_names[remote_count], r->res_name,
			       DLM_RESNAME_MAXLEN);
			remote_count++;

			if (remote_count >= DLM_REMOVE_NAMES_MAX)
				break;
			continue;
		}

		if (!kref_put(&r->res_ref, kill_rsb)) {
			log_error(ls, "tossed rsb in use %s", r->res_name);
			continue;
		}

		rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
		dlm_free_rsb(r);
	}

	if (need_shrink)
		ls->ls_rsbtbl[b].flags |= DLM_RTF_SHRINK;
	else
		ls->ls_rsbtbl[b].flags &= ~DLM_RTF_SHRINK;
	spin_unlock(&ls->ls_rsbtbl[b].lock);

	/*
	 * While searching for rsb's to free, we found some that require
	 * remote removal.  We leave them in place and find them again here
	 * so there is a very small gap between removing them from the toss
	 * list and sending the removal.  Keeping this gap small is
	 * important to keep us (the master node) from being out of sync
	 * with the remote dir node for very long.
	 *
	 * From the time the rsb is removed from toss until just after
	 * send_remove, the rsb name is saved in ls_remove_name.  A new
	 * lookup checks this to ensure that a new lookup message for the
	 * same resource name is not sent just before the remove message.
	 */

	for (i = 0; i < remote_count; i++) {
		name = ls->ls_remove_names[i];
		len = ls->ls_remove_lens[i];

		spin_lock(&ls->ls_rsbtbl[b].lock);
		rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
		if (rv) {
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			log_debug(ls, "remove_name not toss %s", name);
			continue;
		}

		if (r->res_master_nodeid != our_nodeid) {
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			log_debug(ls, "remove_name master %d dir %d our %d %s",
				  r->res_master_nodeid, r->res_dir_nodeid,
				  our_nodeid, name);
			continue;
		}

		if (r->res_dir_nodeid == our_nodeid) {
			/* should never happen */
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			log_error(ls, "remove_name dir %d master %d our %d %s",
				  r->res_dir_nodeid, r->res_master_nodeid,
				  our_nodeid, name);
			continue;
		}

		if (!time_after_eq(jiffies, r->res_toss_time +
				   dlm_config.ci_toss_secs * HZ)) {
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			log_debug(ls, "remove_name toss_time %lu now %lu %s",
				  r->res_toss_time, jiffies, name);
			continue;
		}

		if (!kref_put(&r->res_ref, kill_rsb)) {
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			log_error(ls, "remove_name in use %s", name);
			continue;
		}

		rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);

		/* block lookup of same name until we've sent remove */
		spin_lock(&ls->ls_remove_spin);
		ls->ls_remove_len = len;
		memcpy(ls->ls_remove_name, name, DLM_RESNAME_MAXLEN);
		spin_unlock(&ls->ls_remove_spin);
		spin_unlock(&ls->ls_rsbtbl[b].lock);

		send_remove(r);

		/* allow lookup of name again */
		spin_lock(&ls->ls_remove_spin);
		ls->ls_remove_len = 0;
		memset(ls->ls_remove_name, 0, DLM_RESNAME_MAXLEN);
		spin_unlock(&ls->ls_remove_spin);

		dlm_free_rsb(r);
	}
}

void dlm_scan_rsbs(struct dlm_ls *ls)
{
	int i;

	for (i = 0; i < ls->ls_rsbtbl_size; i++) {
		shrink_bucket(ls, i);
		if (dlm_locking_stopped(ls))
			break;
		cond_resched();
	}
}

static void add_timeout(struct dlm_lkb *lkb)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;

	if (is_master_copy(lkb))
		return;

	if (test_bit(LSFL_TIMEWARN, &ls->ls_flags) &&
	    !(lkb->lkb_exflags & DLM_LKF_NODLCKWT)) {
		lkb->lkb_flags |= DLM_IFL_WATCH_TIMEWARN;
		goto add_it;
	}
	if (lkb->lkb_exflags & DLM_LKF_TIMEOUT)
		goto add_it;
	return;

 add_it:
	DLM_ASSERT(list_empty(&lkb->lkb_time_list), dlm_print_lkb(lkb););
	mutex_lock(&ls->ls_timeout_mutex);
	hold_lkb(lkb);
	list_add_tail(&lkb->lkb_time_list, &ls->ls_timeout);
	mutex_unlock(&ls->ls_timeout_mutex);
}

static void del_timeout(struct dlm_lkb *lkb)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;

	mutex_lock(&ls->ls_timeout_mutex);
	if (!list_empty(&lkb->lkb_time_list)) {
		list_del_init(&lkb->lkb_time_list);
		unhold_lkb(lkb);
	}
	mutex_unlock(&ls->ls_timeout_mutex);
}

/* FIXME: is it safe to look at lkb_exflags, lkb_flags, lkb_timestamp, and
   lkb_lksb_timeout without lock_rsb?  Note: we can't lock timeout_mutex
   and then lock rsb because of lock ordering in add_timeout.  We may need
   to specify some special timeout-related bits in the lkb that are just to
   be accessed under the timeout_mutex. */

void dlm_scan_timeout(struct dlm_ls *ls)
{
	struct dlm_rsb *r;
	struct dlm_lkb *lkb;
	int do_cancel, do_warn;
	s64 wait_us;

	for (;;) {
		if (dlm_locking_stopped(ls))
			break;

		do_cancel = 0;
		do_warn = 0;
		mutex_lock(&ls->ls_timeout_mutex);
		list_for_each_entry(lkb, &ls->ls_timeout, lkb_time_list) {

			wait_us = ktime_to_us(ktime_sub(ktime_get(),
					      		lkb->lkb_timestamp));

			if ((lkb->lkb_exflags & DLM_LKF_TIMEOUT) &&
			    wait_us >= (lkb->lkb_timeout_cs * 10000))
				do_cancel = 1;

			if ((lkb->lkb_flags & DLM_IFL_WATCH_TIMEWARN) &&
			    wait_us >= dlm_config.ci_timewarn_cs * 10000)
				do_warn = 1;

			if (!do_cancel && !do_warn)
				continue;
			hold_lkb(lkb);
			break;
		}
		mutex_unlock(&ls->ls_timeout_mutex);

		if (!do_cancel && !do_warn)
			break;

		r = lkb->lkb_resource;
		hold_rsb(r);
		lock_rsb(r);

		if (do_warn) {
			/* clear flag so we only warn once */
			lkb->lkb_flags &= ~DLM_IFL_WATCH_TIMEWARN;
			if (!(lkb->lkb_exflags & DLM_LKF_TIMEOUT))
				del_timeout(lkb);
			dlm_timeout_warn(lkb);
		}

		if (do_cancel) {
			log_debug(ls, "timeout cancel %x node %d %s",
				  lkb->lkb_id, lkb->lkb_nodeid, r->res_name);
			lkb->lkb_flags &= ~DLM_IFL_WATCH_TIMEWARN;
			lkb->lkb_flags |= DLM_IFL_TIMEOUT_CANCEL;
			del_timeout(lkb);
			_cancel_lock(r, lkb);
		}

		unlock_rsb(r);
		unhold_rsb(r);
		dlm_put_lkb(lkb);
	}
}

/* This is only called by dlm_recoverd, and we rely on dlm_ls_stop() stopping
   dlm_recoverd before checking/setting ls_recover_begin. */

void dlm_adjust_timeouts(struct dlm_ls *ls)
{
	struct dlm_lkb *lkb;
	u64 adj_us = jiffies_to_usecs(jiffies - ls->ls_recover_begin);

	ls->ls_recover_begin = 0;
	mutex_lock(&ls->ls_timeout_mutex);
	list_for_each_entry(lkb, &ls->ls_timeout, lkb_time_list)
		lkb->lkb_timestamp = ktime_add_us(lkb->lkb_timestamp, adj_us);
	mutex_unlock(&ls->ls_timeout_mutex);

	if (!dlm_config.ci_waitwarn_us)
		return;

	mutex_lock(&ls->ls_waiters_mutex);
	list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
		if (ktime_to_us(lkb->lkb_wait_time))
			lkb->lkb_wait_time = ktime_get();
	}
	mutex_unlock(&ls->ls_waiters_mutex);
}

/* lkb is master or local copy */

static void set_lvb_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int b, len = r->res_ls->ls_lvblen;

	/* b=1 lvb returned to caller
	   b=0 lvb written to rsb or invalidated
	   b=-1 do nothing */

	b =  dlm_lvb_operations[lkb->lkb_grmode + 1][lkb->lkb_rqmode + 1];

	if (b == 1) {
		if (!lkb->lkb_lvbptr)
			return;

		if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
			return;

		if (!r->res_lvbptr)
			return;

		memcpy(lkb->lkb_lvbptr, r->res_lvbptr, len);
		lkb->lkb_lvbseq = r->res_lvbseq;

	} else if (b == 0) {
		if (lkb->lkb_exflags & DLM_LKF_IVVALBLK) {
			rsb_set_flag(r, RSB_VALNOTVALID);
			return;
		}

		if (!lkb->lkb_lvbptr)
			return;

		if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
			return;

		if (!r->res_lvbptr)
			r->res_lvbptr = dlm_allocate_lvb(r->res_ls);

		if (!r->res_lvbptr)
			return;

		memcpy(r->res_lvbptr, lkb->lkb_lvbptr, len);
		r->res_lvbseq++;
		lkb->lkb_lvbseq = r->res_lvbseq;
		rsb_clear_flag(r, RSB_VALNOTVALID);
	}

	if (rsb_flag(r, RSB_VALNOTVALID))
		lkb->lkb_sbflags |= DLM_SBF_VALNOTVALID;
}

static void set_lvb_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	if (lkb->lkb_grmode < DLM_LOCK_PW)
		return;

	if (lkb->lkb_exflags & DLM_LKF_IVVALBLK) {
		rsb_set_flag(r, RSB_VALNOTVALID);
		return;
	}

	if (!lkb->lkb_lvbptr)
		return;

	if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
		return;

	if (!r->res_lvbptr)
		r->res_lvbptr = dlm_allocate_lvb(r->res_ls);

	if (!r->res_lvbptr)
		return;

	memcpy(r->res_lvbptr, lkb->lkb_lvbptr, r->res_ls->ls_lvblen);
	r->res_lvbseq++;
	rsb_clear_flag(r, RSB_VALNOTVALID);
}

/* lkb is process copy (pc) */

static void set_lvb_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb,
			    struct dlm_message *ms)
{
	int b;

	if (!lkb->lkb_lvbptr)
		return;

	if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
		return;

	b = dlm_lvb_operations[lkb->lkb_grmode + 1][lkb->lkb_rqmode + 1];
	if (b == 1) {
		int len = receive_extralen(ms);
		if (len > r->res_ls->ls_lvblen)
			len = r->res_ls->ls_lvblen;
		memcpy(lkb->lkb_lvbptr, ms->m_extra, len);
		lkb->lkb_lvbseq = ms->m_lvbseq;
	}
}

/* Manipulate lkb's on rsb's convert/granted/waiting queues
   remove_lock -- used for unlock, removes lkb from granted
   revert_lock -- used for cancel, moves lkb from convert to granted
   grant_lock  -- used for request and convert, adds lkb to granted or
                  moves lkb from convert or waiting to granted

   Each of these is used for master or local copy lkb's.  There is
   also a _pc() variation used to make the corresponding change on
   a process copy (pc) lkb. */

static void _remove_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	del_lkb(r, lkb);
	lkb->lkb_grmode = DLM_LOCK_IV;
	/* this unhold undoes the original ref from create_lkb()
	   so this leads to the lkb being freed */
	unhold_lkb(lkb);
}

static void remove_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	set_lvb_unlock(r, lkb);
	_remove_lock(r, lkb);
}

static void remove_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	_remove_lock(r, lkb);
}

/* returns: 0 did nothing
	    1 moved lock to granted
	   -1 removed lock */

static int revert_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int rv = 0;

	lkb->lkb_rqmode = DLM_LOCK_IV;

	switch (lkb->lkb_status) {
	case DLM_LKSTS_GRANTED:
		break;
	case DLM_LKSTS_CONVERT:
		move_lkb(r, lkb, DLM_LKSTS_GRANTED);
		rv = 1;
		break;
	case DLM_LKSTS_WAITING:
		del_lkb(r, lkb);
		lkb->lkb_grmode = DLM_LOCK_IV;
		/* this unhold undoes the original ref from create_lkb()
		   so this leads to the lkb being freed */
		unhold_lkb(lkb);
		rv = -1;
		break;
	default:
		log_print("invalid status for revert %d", lkb->lkb_status);
	}
	return rv;
}

static int revert_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	return revert_lock(r, lkb);
}

static void _grant_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	if (lkb->lkb_grmode != lkb->lkb_rqmode) {
		lkb->lkb_grmode = lkb->lkb_rqmode;
		if (lkb->lkb_status)
			move_lkb(r, lkb, DLM_LKSTS_GRANTED);
		else
			add_lkb(r, lkb, DLM_LKSTS_GRANTED);
	}

	lkb->lkb_rqmode = DLM_LOCK_IV;
	lkb->lkb_highbast = 0;
}

static void grant_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	set_lvb_lock(r, lkb);
	_grant_lock(r, lkb);
}

static void grant_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb,
			  struct dlm_message *ms)
{
	set_lvb_lock_pc(r, lkb, ms);
	_grant_lock(r, lkb);
}

/* called by grant_pending_locks() which means an async grant message must
   be sent to the requesting node in addition to granting the lock if the
   lkb belongs to a remote node. */

static void grant_lock_pending(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	grant_lock(r, lkb);
	if (is_master_copy(lkb))
		send_grant(r, lkb);
	else
		queue_cast(r, lkb, 0);
}

/* The special CONVDEADLK, ALTPR and ALTCW flags allow the master to
   change the granted/requested modes.  We're munging things accordingly in
   the process copy.
   CONVDEADLK: our grmode may have been forced down to NL to resolve a
   conversion deadlock
   ALTPR/ALTCW: our rqmode may have been changed to PR or CW to become
   compatible with other granted locks */

static void munge_demoted(struct dlm_lkb *lkb)
{
	if (lkb->lkb_rqmode == DLM_LOCK_IV || lkb->lkb_grmode == DLM_LOCK_IV) {
		log_print("munge_demoted %x invalid modes gr %d rq %d",
			  lkb->lkb_id, lkb->lkb_grmode, lkb->lkb_rqmode);
		return;
	}

	lkb->lkb_grmode = DLM_LOCK_NL;
}

static void munge_altmode(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	if (ms->m_type != DLM_MSG_REQUEST_REPLY &&
	    ms->m_type != DLM_MSG_GRANT) {
		log_print("munge_altmode %x invalid reply type %d",
			  lkb->lkb_id, ms->m_type);
		return;
	}

	if (lkb->lkb_exflags & DLM_LKF_ALTPR)
		lkb->lkb_rqmode = DLM_LOCK_PR;
	else if (lkb->lkb_exflags & DLM_LKF_ALTCW)
		lkb->lkb_rqmode = DLM_LOCK_CW;
	else {
		log_print("munge_altmode invalid exflags %x", lkb->lkb_exflags);
		dlm_print_lkb(lkb);
	}
}

static inline int first_in_list(struct dlm_lkb *lkb, struct list_head *head)
{
	struct dlm_lkb *first = list_entry(head->next, struct dlm_lkb,
					   lkb_statequeue);
	if (lkb->lkb_id == first->lkb_id)
		return 1;

	return 0;
}

/* Check if the given lkb conflicts with another lkb on the queue. */

static int queue_conflict(struct list_head *head, struct dlm_lkb *lkb)
{
	struct dlm_lkb *this;

	list_for_each_entry(this, head, lkb_statequeue) {
		if (this == lkb)
			continue;
		if (!modes_compat(this, lkb))
			return 1;
	}
	return 0;
}

/*
 * "A conversion deadlock arises with a pair of lock requests in the converting
 * queue for one resource.  The granted mode of each lock blocks the requested
 * mode of the other lock."
 *
 * Part 2: if the granted mode of lkb is preventing an earlier lkb in the
 * convert queue from being granted, then deadlk/demote lkb.
 *
 * Example:
 * Granted Queue: empty
 * Convert Queue: NL->EX (first lock)
 *                PR->EX (second lock)
 *
 * The first lock can't be granted because of the granted mode of the second
 * lock and the second lock can't be granted because it's not first in the
 * list.  We either cancel lkb's conversion (PR->EX) and return EDEADLK, or we
 * demote the granted mode of lkb (from PR to NL) if it has the CONVDEADLK
 * flag set and return DEMOTED in the lksb flags.
 *
 * Originally, this function detected conv-deadlk in a more limited scope:
 * - if !modes_compat(lkb1, lkb2) && !modes_compat(lkb2, lkb1), or
 * - if lkb1 was the first entry in the queue (not just earlier), and was
 *   blocked by the granted mode of lkb2, and there was nothing on the
 *   granted queue preventing lkb1 from being granted immediately, i.e.
 *   lkb2 was the only thing preventing lkb1 from being granted.
 *
 * That second condition meant we'd only say there was conv-deadlk if
 * resolving it (by demotion) would lead to the first lock on the convert
 * queue being granted right away.  It allowed conversion deadlocks to exist
 * between locks on the convert queue while they couldn't be granted anyway.
 *
 * Now, we detect and take action on conversion deadlocks immediately when
 * they're created, even if they may not be immediately consequential.  If
 * lkb1 exists anywhere in the convert queue and lkb2 comes in with a granted
 * mode that would prevent lkb1's conversion from being granted, we do a
 * deadlk/demote on lkb2 right away and don't let it onto the convert queue.
 * I think this means that the lkb_is_ahead condition below should always
 * be zero, i.e. there will never be conv-deadlk between two locks that are
 * both already on the convert queue.
 */

static int conversion_deadlock_detect(struct dlm_rsb *r, struct dlm_lkb *lkb2)
{
	struct dlm_lkb *lkb1;
	int lkb_is_ahead = 0;

	list_for_each_entry(lkb1, &r->res_convertqueue, lkb_statequeue) {
		if (lkb1 == lkb2) {
			lkb_is_ahead = 1;
			continue;
		}

		if (!lkb_is_ahead) {
			if (!modes_compat(lkb2, lkb1))
				return 1;
		} else {
			if (!modes_compat(lkb2, lkb1) &&
			    !modes_compat(lkb1, lkb2))
				return 1;
		}
	}
	return 0;
}

/*
 * Return 1 if the lock can be granted, 0 otherwise.
 * Also detect and resolve conversion deadlocks.
 *
 * lkb is the lock to be granted
 *
 * now is 1 if the function is being called in the context of the
 * immediate request, it is 0 if called later, after the lock has been
 * queued.
 *
 * recover is 1 if dlm_recover_grant() is trying to grant conversions
 * after recovery.
 *
 * References are from chapter 6 of "VAXcluster Principles" by Roy Davis
 */

static int _can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
			   int recover)
{
	int8_t conv = (lkb->lkb_grmode != DLM_LOCK_IV);

	/*
	 * 6-10: Version 5.4 introduced an option to address the phenomenon of
	 * a new request for a NL mode lock being blocked.
	 *
	 * 6-11: If the optional EXPEDITE flag is used with the new NL mode
	 * request, then it would be granted.  In essence, the use of this flag
	 * tells the Lock Manager to expedite theis request by not considering
	 * what may be in the CONVERTING or WAITING queues...  As of this
	 * writing, the EXPEDITE flag can be used only with new requests for NL
	 * mode locks.  This flag is not valid for conversion requests.
	 *
	 * A shortcut.  Earlier checks return an error if EXPEDITE is used in a
	 * conversion or used with a non-NL requested mode.  We also know an
	 * EXPEDITE request is always granted immediately, so now must always
	 * be 1.  The full condition to grant an expedite request: (now &&
	 * !conv && lkb->rqmode == DLM_LOCK_NL && (flags & EXPEDITE)) can
	 * therefore be shortened to just checking the flag.
	 */

	if (lkb->lkb_exflags & DLM_LKF_EXPEDITE)
		return 1;

	/*
	 * A shortcut. Without this, !queue_conflict(grantqueue, lkb) would be
	 * added to the remaining conditions.
	 */

	if (queue_conflict(&r->res_grantqueue, lkb))
		return 0;

	/*
	 * 6-3: By default, a conversion request is immediately granted if the
	 * requested mode is compatible with the modes of all other granted
	 * locks
	 */

	if (queue_conflict(&r->res_convertqueue, lkb))
		return 0;

	/*
	 * The RECOVER_GRANT flag means dlm_recover_grant() is granting
	 * locks for a recovered rsb, on which lkb's have been rebuilt.
	 * The lkb's may have been rebuilt on the queues in a different
	 * order than they were in on the previous master.  So, granting
	 * queued conversions in order after recovery doesn't make sense
	 * since the order hasn't been preserved anyway.  The new order
	 * could also have created a new "in place" conversion deadlock.
	 * (e.g. old, failed master held granted EX, with PR->EX, NL->EX.
	 * After recovery, there would be no granted locks, and possibly
	 * NL->EX, PR->EX, an in-place conversion deadlock.)  So, after
	 * recovery, grant conversions without considering order.
	 */

	if (conv && recover)
		return 1;

	/*
	 * 6-5: But the default algorithm for deciding whether to grant or
	 * queue conversion requests does not by itself guarantee that such
	 * requests are serviced on a "first come first serve" basis.  This, in
	 * turn, can lead to a phenomenon known as "indefinate postponement".
	 *
	 * 6-7: This issue is dealt with by using the optional QUECVT flag with
	 * the system service employed to request a lock conversion.  This flag
	 * forces certain conversion requests to be queued, even if they are
	 * compatible with the granted modes of other locks on the same
	 * resource.  Thus, the use of this flag results in conversion requests
	 * being ordered on a "first come first servce" basis.
	 *
	 * DCT: This condition is all about new conversions being able to occur
	 * "in place" while the lock remains on the granted queue (assuming
	 * nothing else conflicts.)  IOW if QUECVT isn't set, a conversion
	 * doesn't _have_ to go onto the convert queue where it's processed in
	 * order.  The "now" variable is necessary to distinguish converts
	 * being received and processed for the first time now, because once a
	 * convert is moved to the conversion queue the condition below applies
	 * requiring fifo granting.
	 */

	if (now && conv && !(lkb->lkb_exflags & DLM_LKF_QUECVT))
		return 1;

	/*
	 * Even if the convert is compat with all granted locks,
	 * QUECVT forces it behind other locks on the convert queue.
	 */

	if (now && conv && (lkb->lkb_exflags & DLM_LKF_QUECVT)) {
		if (list_empty(&r->res_convertqueue))
			return 1;
		else
			return 0;
	}

	/*
	 * The NOORDER flag is set to avoid the standard vms rules on grant
	 * order.
	 */

	if (lkb->lkb_exflags & DLM_LKF_NOORDER)
		return 1;

	/*
	 * 6-3: Once in that queue [CONVERTING], a conversion request cannot be
	 * granted until all other conversion requests ahead of it are granted
	 * and/or canceled.
	 */

	if (!now && conv && first_in_list(lkb, &r->res_convertqueue))
		return 1;

	/*
	 * 6-4: By default, a new request is immediately granted only if all
	 * three of the following conditions are satisfied when the request is
	 * issued:
	 * - The queue of ungranted conversion requests for the resource is
	 *   empty.
	 * - The queue of ungranted new requests for the resource is empty.
	 * - The mode of the new request is compatible with the most
	 *   restrictive mode of all granted locks on the resource.
	 */

	if (now && !conv && list_empty(&r->res_convertqueue) &&
	    list_empty(&r->res_waitqueue))
		return 1;

	/*
	 * 6-4: Once a lock request is in the queue of ungranted new requests,
	 * it cannot be granted until the queue of ungranted conversion
	 * requests is empty, all ungranted new requests ahead of it are
	 * granted and/or canceled, and it is compatible with the granted mode
	 * of the most restrictive lock granted on the resource.
	 */

	if (!now && !conv && list_empty(&r->res_convertqueue) &&
	    first_in_list(lkb, &r->res_waitqueue))
		return 1;

	return 0;
}

static int can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
			  int recover, int *err)
{
	int rv;
	int8_t alt = 0, rqmode = lkb->lkb_rqmode;
	int8_t is_convert = (lkb->lkb_grmode != DLM_LOCK_IV);

	if (err)
		*err = 0;

	rv = _can_be_granted(r, lkb, now, recover);
	if (rv)
		goto out;

	/*
	 * The CONVDEADLK flag is non-standard and tells the dlm to resolve
	 * conversion deadlocks by demoting grmode to NL, otherwise the dlm
	 * cancels one of the locks.
	 */

	if (is_convert && can_be_queued(lkb) &&
	    conversion_deadlock_detect(r, lkb)) {
		if (lkb->lkb_exflags & DLM_LKF_CONVDEADLK) {
			lkb->lkb_grmode = DLM_LOCK_NL;
			lkb->lkb_sbflags |= DLM_SBF_DEMOTED;
		} else if (err) {
			*err = -EDEADLK;
		} else {
			log_print("can_be_granted deadlock %x now %d",
				  lkb->lkb_id, now);
			dlm_dump_rsb(r);
		}
		goto out;
	}

	/*
	 * The ALTPR and ALTCW flags are non-standard and tell the dlm to try
	 * to grant a request in a mode other than the normal rqmode.  It's a
	 * simple way to provide a big optimization to applications that can
	 * use them.
	 */

	if (rqmode != DLM_LOCK_PR && (lkb->lkb_exflags & DLM_LKF_ALTPR))
		alt = DLM_LOCK_PR;
	else if (rqmode != DLM_LOCK_CW && (lkb->lkb_exflags & DLM_LKF_ALTCW))
		alt = DLM_LOCK_CW;

	if (alt) {
		lkb->lkb_rqmode = alt;
		rv = _can_be_granted(r, lkb, now, 0);
		if (rv)
			lkb->lkb_sbflags |= DLM_SBF_ALTMODE;
		else
			lkb->lkb_rqmode = rqmode;
	}
 out:
	return rv;
}

/* Returns the highest requested mode of all blocked conversions; sets
   cw if there's a blocked conversion to DLM_LOCK_CW. */

static int grant_pending_convert(struct dlm_rsb *r, int high, int *cw,
				 unsigned int *count)
{
	struct dlm_lkb *lkb, *s;
	int recover = rsb_flag(r, RSB_RECOVER_GRANT);
	int hi, demoted, quit, grant_restart, demote_restart;
	int deadlk;

	quit = 0;
 restart:
	grant_restart = 0;
	demote_restart = 0;
	hi = DLM_LOCK_IV;

	list_for_each_entry_safe(lkb, s, &r->res_convertqueue, lkb_statequeue) {
		demoted = is_demoted(lkb);
		deadlk = 0;

		if (can_be_granted(r, lkb, 0, recover, &deadlk)) {
			grant_lock_pending(r, lkb);
			grant_restart = 1;
			if (count)
				(*count)++;
			continue;
		}

		if (!demoted && is_demoted(lkb)) {
			log_print("WARN: pending demoted %x node %d %s",
				  lkb->lkb_id, lkb->lkb_nodeid, r->res_name);
			demote_restart = 1;
			continue;
		}

		if (deadlk) {
			/*
			 * If DLM_LKB_NODLKWT flag is set and conversion
			 * deadlock is detected, we request blocking AST and
			 * down (or cancel) conversion.
			 */
			if (lkb->lkb_exflags & DLM_LKF_NODLCKWT) {
				if (lkb->lkb_highbast < lkb->lkb_rqmode) {
					queue_bast(r, lkb, lkb->lkb_rqmode);
					lkb->lkb_highbast = lkb->lkb_rqmode;
				}
			} else {
				log_print("WARN: pending deadlock %x node %d %s",
					  lkb->lkb_id, lkb->lkb_nodeid,
					  r->res_name);
				dlm_dump_rsb(r);
			}
			continue;
		}

		hi = max_t(int, lkb->lkb_rqmode, hi);

		if (cw && lkb->lkb_rqmode == DLM_LOCK_CW)
			*cw = 1;
	}

	if (grant_restart)
		goto restart;
	if (demote_restart && !quit) {
		quit = 1;
		goto restart;
	}

	return max_t(int, high, hi);
}

static int grant_pending_wait(struct dlm_rsb *r, int high, int *cw,
			      unsigned int *count)
{
	struct dlm_lkb *lkb, *s;

	list_for_each_entry_safe(lkb, s, &r->res_waitqueue, lkb_statequeue) {
		if (can_be_granted(r, lkb, 0, 0, NULL)) {
			grant_lock_pending(r, lkb);
			if (count)
				(*count)++;
		} else {
			high = max_t(int, lkb->lkb_rqmode, high);
			if (lkb->lkb_rqmode == DLM_LOCK_CW)
				*cw = 1;
		}
	}

	return high;
}

/* cw of 1 means there's a lock with a rqmode of DLM_LOCK_CW that's blocked
   on either the convert or waiting queue.
   high is the largest rqmode of all locks blocked on the convert or
   waiting queue. */

static int lock_requires_bast(struct dlm_lkb *gr, int high, int cw)
{
	if (gr->lkb_grmode == DLM_LOCK_PR && cw) {
		if (gr->lkb_highbast < DLM_LOCK_EX)
			return 1;
		return 0;
	}

	if (gr->lkb_highbast < high &&
	    !__dlm_compat_matrix[gr->lkb_grmode+1][high+1])
		return 1;
	return 0;
}

static void grant_pending_locks(struct dlm_rsb *r, unsigned int *count)
{
	struct dlm_lkb *lkb, *s;
	int high = DLM_LOCK_IV;
	int cw = 0;

	if (!is_master(r)) {
		log_print("grant_pending_locks r nodeid %d", r->res_nodeid);
		dlm_dump_rsb(r);
		return;
	}

	high = grant_pending_convert(r, high, &cw, count);
	high = grant_pending_wait(r, high, &cw, count);

	if (high == DLM_LOCK_IV)
		return;

	/*
	 * If there are locks left on the wait/convert queue then send blocking
	 * ASTs to granted locks based on the largest requested mode (high)
	 * found above.
	 */

	list_for_each_entry_safe(lkb, s, &r->res_grantqueue, lkb_statequeue) {
		if (lkb->lkb_bastfn && lock_requires_bast(lkb, high, cw)) {
			if (cw && high == DLM_LOCK_PR &&
			    lkb->lkb_grmode == DLM_LOCK_PR)
				queue_bast(r, lkb, DLM_LOCK_CW);
			else
				queue_bast(r, lkb, high);
			lkb->lkb_highbast = high;
		}
	}
}

static int modes_require_bast(struct dlm_lkb *gr, struct dlm_lkb *rq)
{
	if ((gr->lkb_grmode == DLM_LOCK_PR && rq->lkb_rqmode == DLM_LOCK_CW) ||
	    (gr->lkb_grmode == DLM_LOCK_CW && rq->lkb_rqmode == DLM_LOCK_PR)) {
		if (gr->lkb_highbast < DLM_LOCK_EX)
			return 1;
		return 0;
	}

	if (gr->lkb_highbast < rq->lkb_rqmode && !modes_compat(gr, rq))
		return 1;
	return 0;
}

static void send_bast_queue(struct dlm_rsb *r, struct list_head *head,
			    struct dlm_lkb *lkb)
{
	struct dlm_lkb *gr;

	list_for_each_entry(gr, head, lkb_statequeue) {
		/* skip self when sending basts to convertqueue */
		if (gr == lkb)
			continue;
		if (gr->lkb_bastfn && modes_require_bast(gr, lkb)) {
			queue_bast(r, gr, lkb->lkb_rqmode);
			gr->lkb_highbast = lkb->lkb_rqmode;
		}
	}
}

static void send_blocking_asts(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	send_bast_queue(r, &r->res_grantqueue, lkb);
}

static void send_blocking_asts_all(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	send_bast_queue(r, &r->res_grantqueue, lkb);
	send_bast_queue(r, &r->res_convertqueue, lkb);
}

/* set_master(r, lkb) -- set the master nodeid of a resource

   The purpose of this function is to set the nodeid field in the given
   lkb using the nodeid field in the given rsb.  If the rsb's nodeid is
   known, it can just be copied to the lkb and the function will return
   0.  If the rsb's nodeid is _not_ known, it needs to be looked up
   before it can be copied to the lkb.

   When the rsb nodeid is being looked up remotely, the initial lkb
   causing the lookup is kept on the ls_waiters list waiting for the
   lookup reply.  Other lkb's waiting for the same rsb lookup are kept
   on the rsb's res_lookup list until the master is verified.

   Return values:
   0: nodeid is set in rsb/lkb and the caller should go ahead and use it
   1: the rsb master is not available and the lkb has been placed on
      a wait queue
*/

static int set_master(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int our_nodeid = dlm_our_nodeid();

	if (rsb_flag(r, RSB_MASTER_UNCERTAIN)) {
		rsb_clear_flag(r, RSB_MASTER_UNCERTAIN);
		r->res_first_lkid = lkb->lkb_id;
		lkb->lkb_nodeid = r->res_nodeid;
		return 0;
	}

	if (r->res_first_lkid && r->res_first_lkid != lkb->lkb_id) {
		list_add_tail(&lkb->lkb_rsb_lookup, &r->res_lookup);
		return 1;
	}

	if (r->res_master_nodeid == our_nodeid) {
		lkb->lkb_nodeid = 0;
		return 0;
	}

	if (r->res_master_nodeid) {
		lkb->lkb_nodeid = r->res_master_nodeid;
		return 0;
	}

	if (dlm_dir_nodeid(r) == our_nodeid) {
		/* This is a somewhat unusual case; find_rsb will usually
		   have set res_master_nodeid when dir nodeid is local, but
		   there are cases where we become the dir node after we've
		   past find_rsb and go through _request_lock again.
		   confirm_master() or process_lookup_list() needs to be
		   called after this. */
		log_debug(r->res_ls, "set_master %x self master %d dir %d %s",
			  lkb->lkb_id, r->res_master_nodeid, r->res_dir_nodeid,
			  r->res_name);
		r->res_master_nodeid = our_nodeid;
		r->res_nodeid = 0;
		lkb->lkb_nodeid = 0;
		return 0;
	}

	wait_pending_remove(r);

	r->res_first_lkid = lkb->lkb_id;
	send_lookup(r, lkb);
	return 1;
}

static void process_lookup_list(struct dlm_rsb *r)
{
	struct dlm_lkb *lkb, *safe;

	list_for_each_entry_safe(lkb, safe, &r->res_lookup, lkb_rsb_lookup) {
		list_del_init(&lkb->lkb_rsb_lookup);
		_request_lock(r, lkb);
		schedule();
	}
}

/* confirm_master -- confirm (or deny) an rsb's master nodeid */

static void confirm_master(struct dlm_rsb *r, int error)
{
	struct dlm_lkb *lkb;

	if (!r->res_first_lkid)
		return;

	switch (error) {
	case 0:
	case -EINPROGRESS:
		r->res_first_lkid = 0;
		process_lookup_list(r);
		break;

	case -EAGAIN:
	case -EBADR:
	case -ENOTBLK:
		/* the remote request failed and won't be retried (it was
		   a NOQUEUE, or has been canceled/unlocked); make a waiting
		   lkb the first_lkid */

		r->res_first_lkid = 0;

		if (!list_empty(&r->res_lookup)) {
			lkb = list_entry(r->res_lookup.next, struct dlm_lkb,
					 lkb_rsb_lookup);
			list_del_init(&lkb->lkb_rsb_lookup);
			r->res_first_lkid = lkb->lkb_id;
			_request_lock(r, lkb);
		}
		break;

	default:
		log_error(r->res_ls, "confirm_master unknown error %d", error);
	}
}

static int set_lock_args(int mode, struct dlm_lksb *lksb, uint32_t flags,
			 int namelen, unsigned long timeout_cs,
			 void (*ast) (void *astparam),
			 void *astparam,
			 void (*bast) (void *astparam, int mode),
			 struct dlm_args *args)
{
	int rv = -EINVAL;

	/* check for invalid arg usage */

	if (mode < 0 || mode > DLM_LOCK_EX)
		goto out;

	if (!(flags & DLM_LKF_CONVERT) && (namelen > DLM_RESNAME_MAXLEN))
		goto out;

	if (flags & DLM_LKF_CANCEL)
		goto out;

	if (flags & DLM_LKF_QUECVT && !(flags & DLM_LKF_CONVERT))
		goto out;

	if (flags & DLM_LKF_CONVDEADLK && !(flags & DLM_LKF_CONVERT))
		goto out;

	if (flags & DLM_LKF_CONVDEADLK && flags & DLM_LKF_NOQUEUE)
		goto out;

	if (flags & DLM_LKF_EXPEDITE && flags & DLM_LKF_CONVERT)
		goto out;

	if (flags & DLM_LKF_EXPEDITE && flags & DLM_LKF_QUECVT)
		goto out;

	if (flags & DLM_LKF_EXPEDITE && flags & DLM_LKF_NOQUEUE)
		goto out;

	if (flags & DLM_LKF_EXPEDITE && mode != DLM_LOCK_NL)
		goto out;

	if (!ast || !lksb)
		goto out;

	if (flags & DLM_LKF_VALBLK && !lksb->sb_lvbptr)
		goto out;

	if (flags & DLM_LKF_CONVERT && !lksb->sb_lkid)
		goto out;

	/* these args will be copied to the lkb in validate_lock_args,
	   it cannot be done now because when converting locks, fields in
	   an active lkb cannot be modified before locking the rsb */

	args->flags = flags;
	args->astfn = ast;
	args->astparam = astparam;
	args->bastfn = bast;
	args->timeout = timeout_cs;
	args->mode = mode;
	args->lksb = lksb;
	rv = 0;
 out:
	return rv;
}

static int set_unlock_args(uint32_t flags, void *astarg, struct dlm_args *args)
{
	if (flags & ~(DLM_LKF_CANCEL | DLM_LKF_VALBLK | DLM_LKF_IVVALBLK |
 		      DLM_LKF_FORCEUNLOCK))
		return -EINVAL;

	if (flags & DLM_LKF_CANCEL && flags & DLM_LKF_FORCEUNLOCK)
		return -EINVAL;

	args->flags = flags;
	args->astparam = astarg;
	return 0;
}

static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
			      struct dlm_args *args)
{
	int rv = -EINVAL;

	if (args->flags & DLM_LKF_CONVERT) {
		if (lkb->lkb_flags & DLM_IFL_MSTCPY)
			goto out;

		if (args->flags & DLM_LKF_QUECVT &&
		    !__quecvt_compat_matrix[lkb->lkb_grmode+1][args->mode+1])
			goto out;

		rv = -EBUSY;
		if (lkb->lkb_status != DLM_LKSTS_GRANTED)
			goto out;

		if (lkb->lkb_wait_type)
			goto out;

		if (is_overlap(lkb))
			goto out;
	}

	lkb->lkb_exflags = args->flags;
	lkb->lkb_sbflags = 0;
	lkb->lkb_astfn = args->astfn;
	lkb->lkb_astparam = args->astparam;
	lkb->lkb_bastfn = args->bastfn;
	lkb->lkb_rqmode = args->mode;
	lkb->lkb_lksb = args->lksb;
	lkb->lkb_lvbptr = args->lksb->sb_lvbptr;
	lkb->lkb_ownpid = (int) current->pid;
	lkb->lkb_timeout_cs = args->timeout;
	rv = 0;
 out:
	if (rv)
		log_debug(ls, "validate_lock_args %d %x %x %x %d %d %s",
			  rv, lkb->lkb_id, lkb->lkb_flags, args->flags,
			  lkb->lkb_status, lkb->lkb_wait_type,
			  lkb->lkb_resource->res_name);
	return rv;
}

/* when dlm_unlock() sees -EBUSY with CANCEL/FORCEUNLOCK it returns 0
   for success */

/* note: it's valid for lkb_nodeid/res_nodeid to be -1 when we get here
   because there may be a lookup in progress and it's valid to do
   cancel/unlockf on it */

static int validate_unlock_args(struct dlm_lkb *lkb, struct dlm_args *args)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
	int rv = -EINVAL;

	if (lkb->lkb_flags & DLM_IFL_MSTCPY) {
		log_error(ls, "unlock on MSTCPY %x", lkb->lkb_id);
		dlm_print_lkb(lkb);
		goto out;
	}

	/* an lkb may still exist even though the lock is EOL'ed due to a
	   cancel, unlock or failed noqueue request; an app can't use these
	   locks; return same error as if the lkid had not been found at all */

	if (lkb->lkb_flags & DLM_IFL_ENDOFLIFE) {
		log_debug(ls, "unlock on ENDOFLIFE %x", lkb->lkb_id);
		rv = -ENOENT;
		goto out;
	}

	/* an lkb may be waiting for an rsb lookup to complete where the
	   lookup was initiated by another lock */

	if (!list_empty(&lkb->lkb_rsb_lookup)) {
		if (args->flags & (DLM_LKF_CANCEL | DLM_LKF_FORCEUNLOCK)) {
			log_debug(ls, "unlock on rsb_lookup %x", lkb->lkb_id);
			list_del_init(&lkb->lkb_rsb_lookup);
			queue_cast(lkb->lkb_resource, lkb,
				   args->flags & DLM_LKF_CANCEL ?
				   -DLM_ECANCEL : -DLM_EUNLOCK);
			unhold_lkb(lkb); /* undoes create_lkb() */
		}
		/* caller changes -EBUSY to 0 for CANCEL and FORCEUNLOCK */
		rv = -EBUSY;
		goto out;
	}

	/* cancel not allowed with another cancel/unlock in progress */

	if (args->flags & DLM_LKF_CANCEL) {
		if (lkb->lkb_exflags & DLM_LKF_CANCEL)
			goto out;

		if (is_overlap(lkb))
			goto out;

		/* don't let scand try to do a cancel */
		del_timeout(lkb);

		if (lkb->lkb_flags & DLM_IFL_RESEND) {
			lkb->lkb_flags |= DLM_IFL_OVERLAP_CANCEL;
			rv = -EBUSY;
			goto out;
		}

		/* there's nothing to cancel */
		if (lkb->lkb_status == DLM_LKSTS_GRANTED &&
		    !lkb->lkb_wait_type) {
			rv = -EBUSY;
			goto out;
		}

		switch (lkb->lkb_wait_type) {
		case DLM_MSG_LOOKUP:
		case DLM_MSG_REQUEST:
			lkb->lkb_flags |= DLM_IFL_OVERLAP_CANCEL;
			rv = -EBUSY;
			goto out;
		case DLM_MSG_UNLOCK:
		case DLM_MSG_CANCEL:
			goto out;
		}
		/* add_to_waiters() will set OVERLAP_CANCEL */
		goto out_ok;
	}

	/* do we need to allow a force-unlock if there's a normal unlock
	   already in progress?  in what conditions could the normal unlock
	   fail such that we'd want to send a force-unlock to be sure? */

	if (args->flags & DLM_LKF_FORCEUNLOCK) {
		if (lkb->lkb_exflags & DLM_LKF_FORCEUNLOCK)
			goto out;

		if (is_overlap_unlock(lkb))
			goto out;

		/* don't let scand try to do a cancel */
		del_timeout(lkb);

		if (lkb->lkb_flags & DLM_IFL_RESEND) {
			lkb->lkb_flags |= DLM_IFL_OVERLAP_UNLOCK;
			rv = -EBUSY;
			goto out;
		}

		switch (lkb->lkb_wait_type) {
		case DLM_MSG_LOOKUP:
		case DLM_MSG_REQUEST:
			lkb->lkb_flags |= DLM_IFL_OVERLAP_UNLOCK;
			rv = -EBUSY;
			goto out;
		case DLM_MSG_UNLOCK:
			goto out;
		}
		/* add_to_waiters() will set OVERLAP_UNLOCK */
		goto out_ok;
	}

	/* normal unlock not allowed if there's any op in progress */
	rv = -EBUSY;
	if (lkb->lkb_wait_type || lkb->lkb_wait_count)
		goto out;

 out_ok:
	/* an overlapping op shouldn't blow away exflags from other op */
	lkb->lkb_exflags |= args->flags;
	lkb->lkb_sbflags = 0;
	lkb->lkb_astparam = args->astparam;
	rv = 0;
 out:
	if (rv)
		log_debug(ls, "validate_unlock_args %d %x %x %x %x %d %s", rv,
			  lkb->lkb_id, lkb->lkb_flags, lkb->lkb_exflags,
			  args->flags, lkb->lkb_wait_type,
			  lkb->lkb_resource->res_name);
	return rv;
}

/*
 * Four stage 4 varieties:
 * do_request(), do_convert(), do_unlock(), do_cancel()
 * These are called on the master node for the given lock and
 * from the central locking logic.
 */

static int do_request(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error = 0;

	if (can_be_granted(r, lkb, 1, 0, NULL)) {
		grant_lock(r, lkb);
		queue_cast(r, lkb, 0);
		goto out;
	}

	if (can_be_queued(lkb)) {
		error = -EINPROGRESS;
		add_lkb(r, lkb, DLM_LKSTS_WAITING);
		add_timeout(lkb);
		goto out;
	}

	error = -EAGAIN;
	queue_cast(r, lkb, -EAGAIN);
 out:
	return error;
}

static void do_request_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
			       int error)
{
	switch (error) {
	case -EAGAIN:
		if (force_blocking_asts(lkb))
			send_blocking_asts_all(r, lkb);
		break;
	case -EINPROGRESS:
		send_blocking_asts(r, lkb);
		break;
	}
}

static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error = 0;
	int deadlk = 0;

	/* changing an existing lock may allow others to be granted */

	if (can_be_granted(r, lkb, 1, 0, &deadlk)) {
		grant_lock(r, lkb);
		queue_cast(r, lkb, 0);
		goto out;
	}

	/* can_be_granted() detected that this lock would block in a conversion
	   deadlock, so we leave it on the granted queue and return EDEADLK in
	   the ast for the convert. */

	if (deadlk && !(lkb->lkb_exflags & DLM_LKF_NODLCKWT)) {
		/* it's left on the granted queue */
		revert_lock(r, lkb);
		queue_cast(r, lkb, -EDEADLK);
		error = -EDEADLK;
		goto out;
	}

	/* is_demoted() means the can_be_granted() above set the grmode
	   to NL, and left us on the granted queue.  This auto-demotion
	   (due to CONVDEADLK) might mean other locks, and/or this lock, are
	   now grantable.  We have to try to grant other converting locks
	   before we try again to grant this one. */

	if (is_demoted(lkb)) {
		grant_pending_convert(r, DLM_LOCK_IV, NULL, NULL);
		if (_can_be_granted(r, lkb, 1, 0)) {
			grant_lock(r, lkb);
			queue_cast(r, lkb, 0);
			goto out;
		}
		/* else fall through and move to convert queue */
	}

	if (can_be_queued(lkb)) {
		error = -EINPROGRESS;
		del_lkb(r, lkb);
		add_lkb(r, lkb, DLM_LKSTS_CONVERT);
		add_timeout(lkb);
		goto out;
	}

	error = -EAGAIN;
	queue_cast(r, lkb, -EAGAIN);
 out:
	return error;
}

static void do_convert_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
			       int error)
{
	switch (error) {
	case 0:
		grant_pending_locks(r, NULL);
		/* grant_pending_locks also sends basts */
		break;
	case -EAGAIN:
		if (force_blocking_asts(lkb))
			send_blocking_asts_all(r, lkb);
		break;
	case -EINPROGRESS:
		send_blocking_asts(r, lkb);
		break;
	}
}

static int do_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	remove_lock(r, lkb);
	queue_cast(r, lkb, -DLM_EUNLOCK);
	return -DLM_EUNLOCK;
}

static void do_unlock_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
			      int error)
{
	grant_pending_locks(r, NULL);
}

/* returns: 0 did nothing, -DLM_ECANCEL canceled lock */

static int do_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error;

	error = revert_lock(r, lkb);
	if (error) {
		queue_cast(r, lkb, -DLM_ECANCEL);
		return -DLM_ECANCEL;
	}
	return 0;
}

static void do_cancel_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
			      int error)
{
	if (error)
		grant_pending_locks(r, NULL);
}

/*
 * Four stage 3 varieties:
 * _request_lock(), _convert_lock(), _unlock_lock(), _cancel_lock()
 */

/* add a new lkb to a possibly new rsb, called by requesting process */

static int _request_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error;

	/* set_master: sets lkb nodeid from r */

	error = set_master(r, lkb);
	if (error < 0)
		goto out;
	if (error) {
		error = 0;
		goto out;
	}

	if (is_remote(r)) {
		/* receive_request() calls do_request() on remote node */
		error = send_request(r, lkb);
	} else {
		error = do_request(r, lkb);
		/* for remote locks the request_reply is sent
		   between do_request and do_request_effects */
		do_request_effects(r, lkb, error);
	}
 out:
	return error;
}

/* change some property of an existing lkb, e.g. mode */

static int _convert_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error;

	if (is_remote(r)) {
		/* receive_convert() calls do_convert() on remote node */
		error = send_convert(r, lkb);
	} else {
		error = do_convert(r, lkb);
		/* for remote locks the convert_reply is sent
		   between do_convert and do_convert_effects */
		do_convert_effects(r, lkb, error);
	}

	return error;
}

/* remove an existing lkb from the granted queue */

static int _unlock_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error;

	if (is_remote(r)) {
		/* receive_unlock() calls do_unlock() on remote node */
		error = send_unlock(r, lkb);
	} else {
		error = do_unlock(r, lkb);
		/* for remote locks the unlock_reply is sent
		   between do_unlock and do_unlock_effects */
		do_unlock_effects(r, lkb, error);
	}

	return error;
}

/* remove an existing lkb from the convert or wait queue */

static int _cancel_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error;

	if (is_remote(r)) {
		/* receive_cancel() calls do_cancel() on remote node */
		error = send_cancel(r, lkb);
	} else {
		error = do_cancel(r, lkb);
		/* for remote locks the cancel_reply is sent
		   between do_cancel and do_cancel_effects */
		do_cancel_effects(r, lkb, error);
	}

	return error;
}

/*
 * Four stage 2 varieties:
 * request_lock(), convert_lock(), unlock_lock(), cancel_lock()
 */

static int request_lock(struct dlm_ls *ls, struct dlm_lkb *lkb, char *name,
			int len, struct dlm_args *args)
{
	struct dlm_rsb *r;
	int error;

	error = validate_lock_args(ls, lkb, args);
	if (error)
		return error;

	error = find_rsb(ls, name, len, 0, R_REQUEST, &r);
	if (error)
		return error;

	lock_rsb(r);

	attach_lkb(r, lkb);
	lkb->lkb_lksb->sb_lkid = lkb->lkb_id;

	error = _request_lock(r, lkb);

	unlock_rsb(r);
	put_rsb(r);
	return error;
}

static int convert_lock(struct dlm_ls *ls, struct dlm_lkb *lkb,
			struct dlm_args *args)
{
	struct dlm_rsb *r;
	int error;

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_lock_args(ls, lkb, args);
	if (error)
		goto out;

	error = _convert_lock(r, lkb);
 out:
	unlock_rsb(r);
	put_rsb(r);
	return error;
}

static int unlock_lock(struct dlm_ls *ls, struct dlm_lkb *lkb,
		       struct dlm_args *args)
{
	struct dlm_rsb *r;
	int error;

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_unlock_args(lkb, args);
	if (error)
		goto out;

	error = _unlock_lock(r, lkb);
 out:
	unlock_rsb(r);
	put_rsb(r);
	return error;
}

static int cancel_lock(struct dlm_ls *ls, struct dlm_lkb *lkb,
		       struct dlm_args *args)
{
	struct dlm_rsb *r;
	int error;

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_unlock_args(lkb, args);
	if (error)
		goto out;

	error = _cancel_lock(r, lkb);
 out:
	unlock_rsb(r);
	put_rsb(r);
	return error;
}

/*
 * Two stage 1 varieties:  dlm_lock() and dlm_unlock()
 */

int dlm_lock(dlm_lockspace_t *lockspace,
	     int mode,
	     struct dlm_lksb *lksb,
	     uint32_t flags,
	     void *name,
	     unsigned int namelen,
	     uint32_t parent_lkid,
	     void (*ast) (void *astarg),
	     void *astarg,
	     void (*bast) (void *astarg, int mode))
{
	struct dlm_ls *ls;
	struct dlm_lkb *lkb;
	struct dlm_args args;
	int error, convert = flags & DLM_LKF_CONVERT;

	ls = dlm_find_lockspace_local(lockspace);
	if (!ls)
		return -EINVAL;

	dlm_lock_recovery(ls);

	if (convert)
		error = find_lkb(ls, lksb->sb_lkid, &lkb);
	else
		error = create_lkb(ls, &lkb);

	if (error)
		goto out;

	error = set_lock_args(mode, lksb, flags, namelen, 0, ast,
			      astarg, bast, &args);
	if (error)
		goto out_put;

	if (convert)
		error = convert_lock(ls, lkb, &args);
	else
		error = request_lock(ls, lkb, name, namelen, &args);

	if (error == -EINPROGRESS)
		error = 0;
 out_put:
	if (convert || error)
		__put_lkb(ls, lkb);
	if (error == -EAGAIN || error == -EDEADLK)
		error = 0;
 out:
	dlm_unlock_recovery(ls);
	dlm_put_lockspace(ls);
	return error;
}

int dlm_unlock(dlm_lockspace_t *lockspace,
	       uint32_t lkid,
	       uint32_t flags,
	       struct dlm_lksb *lksb,
	       void *astarg)
{
	struct dlm_ls *ls;
	struct dlm_lkb *lkb;
	struct dlm_args args;
	int error;

	ls = dlm_find_lockspace_local(lockspace);
	if (!ls)
		return -EINVAL;

	dlm_lock_recovery(ls);

	error = find_lkb(ls, lkid, &lkb);
	if (error)
		goto out;

	error = set_unlock_args(flags, astarg, &args);
	if (error)
		goto out_put;

	if (flags & DLM_LKF_CANCEL)
		error = cancel_lock(ls, lkb, &args);
	else
		error = unlock_lock(ls, lkb, &args);

	if (error == -DLM_EUNLOCK || error == -DLM_ECANCEL)
		error = 0;
	if (error == -EBUSY && (flags & (DLM_LKF_CANCEL | DLM_LKF_FORCEUNLOCK)))
		error = 0;
 out_put:
	dlm_put_lkb(lkb);
 out:
	dlm_unlock_recovery(ls);
	dlm_put_lockspace(ls);
	return error;
}

/*
 * send/receive routines for remote operations and replies
 *
 * send_args
 * send_common
 * send_request			receive_request
 * send_convert			receive_convert
 * send_unlock			receive_unlock
 * send_cancel			receive_cancel
 * send_grant			receive_grant
 * send_bast			receive_bast
 * send_lookup			receive_lookup
 * send_remove			receive_remove
 *
 * 				send_common_reply
 * receive_request_reply	send_request_reply
 * receive_convert_reply	send_convert_reply
 * receive_unlock_reply		send_unlock_reply
 * receive_cancel_reply		send_cancel_reply
 * receive_lookup_reply		send_lookup_reply
 */

static int _create_message(struct dlm_ls *ls, int mb_len,
			   int to_nodeid, int mstype,
			   struct dlm_message **ms_ret,
			   struct dlm_mhandle **mh_ret)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	char *mb;

	/* get_buffer gives us a message handle (mh) that we need to
	   pass into lowcomms_commit and a message buffer (mb) that we
	   write our data into */

	mh = dlm_lowcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
	if (!mh)
		return -ENOBUFS;

	ms = (struct dlm_message *) mb;

	ms->m_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
	ms->m_header.h_lockspace = ls->ls_global_id;
	ms->m_header.h_nodeid = dlm_our_nodeid();
	ms->m_header.h_length = mb_len;
	ms->m_header.h_cmd = DLM_MSG;

	ms->m_type = mstype;

	*mh_ret = mh;
	*ms_ret = ms;
	return 0;
}

static int create_message(struct dlm_rsb *r, struct dlm_lkb *lkb,
			  int to_nodeid, int mstype,
			  struct dlm_message **ms_ret,
			  struct dlm_mhandle **mh_ret)
{
	int mb_len = sizeof(struct dlm_message);

	switch (mstype) {
	case DLM_MSG_REQUEST:
	case DLM_MSG_LOOKUP:
	case DLM_MSG_REMOVE:
		mb_len += r->res_length;
		break;
	case DLM_MSG_CONVERT:
	case DLM_MSG_UNLOCK:
	case DLM_MSG_REQUEST_REPLY:
	case DLM_MSG_CONVERT_REPLY:
	case DLM_MSG_GRANT:
		if (lkb && lkb->lkb_lvbptr)
			mb_len += r->res_ls->ls_lvblen;
		break;
	}

	return _create_message(r->res_ls, mb_len, to_nodeid, mstype,
			       ms_ret, mh_ret);
}

/* further lowcomms enhancements or alternate implementations may make
   the return value from this function useful at some point */

static int send_message(struct dlm_mhandle *mh, struct dlm_message *ms)
{
	dlm_message_out(ms);
	dlm_lowcomms_commit_buffer(mh);
	return 0;
}

static void send_args(struct dlm_rsb *r, struct dlm_lkb *lkb,
		      struct dlm_message *ms)
{
	ms->m_nodeid   = lkb->lkb_nodeid;
	ms->m_pid      = lkb->lkb_ownpid;
	ms->m_lkid     = lkb->lkb_id;
	ms->m_remid    = lkb->lkb_remid;
	ms->m_exflags  = lkb->lkb_exflags;
	ms->m_sbflags  = lkb->lkb_sbflags;
	ms->m_flags    = lkb->lkb_flags;
	ms->m_lvbseq   = lkb->lkb_lvbseq;
	ms->m_status   = lkb->lkb_status;
	ms->m_grmode   = lkb->lkb_grmode;
	ms->m_rqmode   = lkb->lkb_rqmode;
	ms->m_hash     = r->res_hash;

	/* m_result and m_bastmode are set from function args,
	   not from lkb fields */

	if (lkb->lkb_bastfn)
		ms->m_asts |= DLM_CB_BAST;
	if (lkb->lkb_astfn)
		ms->m_asts |= DLM_CB_CAST;

	/* compare with switch in create_message; send_remove() doesn't
	   use send_args() */

	switch (ms->m_type) {
	case DLM_MSG_REQUEST:
	case DLM_MSG_LOOKUP:
		memcpy(ms->m_extra, r->res_name, r->res_length);
		break;
	case DLM_MSG_CONVERT:
	case DLM_MSG_UNLOCK:
	case DLM_MSG_REQUEST_REPLY:
	case DLM_MSG_CONVERT_REPLY:
	case DLM_MSG_GRANT:
		if (!lkb->lkb_lvbptr)
			break;
		memcpy(ms->m_extra, lkb->lkb_lvbptr, r->res_ls->ls_lvblen);
		break;
	}
}

static int send_common(struct dlm_rsb *r, struct dlm_lkb *lkb, int mstype)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int to_nodeid, error;

	to_nodeid = r->res_nodeid;

	error = add_to_waiters(lkb, mstype, to_nodeid);
	if (error)
		return error;

	error = create_message(r, lkb, to_nodeid, mstype, &ms, &mh);
	if (error)
		goto fail;

	send_args(r, lkb, ms);

	error = send_message(mh, ms);
	if (error)
		goto fail;
	return 0;

 fail:
	remove_from_waiters(lkb, msg_reply_type(mstype));
	return error;
}

static int send_request(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	return send_common(r, lkb, DLM_MSG_REQUEST);
}

static int send_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	int error;

	error = send_common(r, lkb, DLM_MSG_CONVERT);

	/* down conversions go without a reply from the master */
	if (!error && down_conversion(lkb)) {
		remove_from_waiters(lkb, DLM_MSG_CONVERT_REPLY);
		r->res_ls->ls_stub_ms.m_flags = DLM_IFL_STUB_MS;
		r->res_ls->ls_stub_ms.m_type = DLM_MSG_CONVERT_REPLY;
		r->res_ls->ls_stub_ms.m_result = 0;
		__receive_convert_reply(r, lkb, &r->res_ls->ls_stub_ms);
	}

	return error;
}

/* FIXME: if this lkb is the only lock we hold on the rsb, then set
   MASTER_UNCERTAIN to force the next request on the rsb to confirm
   that the master is still correct. */

static int send_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	return send_common(r, lkb, DLM_MSG_UNLOCK);
}

static int send_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	return send_common(r, lkb, DLM_MSG_CANCEL);
}

static int send_grant(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int to_nodeid, error;

	to_nodeid = lkb->lkb_nodeid;

	error = create_message(r, lkb, to_nodeid, DLM_MSG_GRANT, &ms, &mh);
	if (error)
		goto out;

	send_args(r, lkb, ms);

	ms->m_result = 0;

	error = send_message(mh, ms);
 out:
	return error;
}

static int send_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int mode)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int to_nodeid, error;

	to_nodeid = lkb->lkb_nodeid;

	error = create_message(r, NULL, to_nodeid, DLM_MSG_BAST, &ms, &mh);
	if (error)
		goto out;

	send_args(r, lkb, ms);

	ms->m_bastmode = mode;

	error = send_message(mh, ms);
 out:
	return error;
}

static int send_lookup(struct dlm_rsb *r, struct dlm_lkb *lkb)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int to_nodeid, error;

	to_nodeid = dlm_dir_nodeid(r);

	error = add_to_waiters(lkb, DLM_MSG_LOOKUP, to_nodeid);
	if (error)
		return error;

	error = create_message(r, NULL, to_nodeid, DLM_MSG_LOOKUP, &ms, &mh);
	if (error)
		goto fail;

	send_args(r, lkb, ms);

	error = send_message(mh, ms);
	if (error)
		goto fail;
	return 0;

 fail:
	remove_from_waiters(lkb, DLM_MSG_LOOKUP_REPLY);
	return error;
}

static int send_remove(struct dlm_rsb *r)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int to_nodeid, error;

	to_nodeid = dlm_dir_nodeid(r);

	error = create_message(r, NULL, to_nodeid, DLM_MSG_REMOVE, &ms, &mh);
	if (error)
		goto out;

	memcpy(ms->m_extra, r->res_name, r->res_length);
	ms->m_hash = r->res_hash;

	error = send_message(mh, ms);
 out:
	return error;
}

static int send_common_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
			     int mstype, int rv)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int to_nodeid, error;

	to_nodeid = lkb->lkb_nodeid;

	error = create_message(r, lkb, to_nodeid, mstype, &ms, &mh);
	if (error)
		goto out;

	send_args(r, lkb, ms);

	ms->m_result = rv;

	error = send_message(mh, ms);
 out:
	return error;
}

static int send_request_reply(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
{
	return send_common_reply(r, lkb, DLM_MSG_REQUEST_REPLY, rv);
}

static int send_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
{
	return send_common_reply(r, lkb, DLM_MSG_CONVERT_REPLY, rv);
}

static int send_unlock_reply(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
{
	return send_common_reply(r, lkb, DLM_MSG_UNLOCK_REPLY, rv);
}

static int send_cancel_reply(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
{
	return send_common_reply(r, lkb, DLM_MSG_CANCEL_REPLY, rv);
}

static int send_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms_in,
			     int ret_nodeid, int rv)
{
	struct dlm_rsb *r = &ls->ls_stub_rsb;
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int error, nodeid = ms_in->m_header.h_nodeid;

	error = create_message(r, NULL, nodeid, DLM_MSG_LOOKUP_REPLY, &ms, &mh);
	if (error)
		goto out;

	ms->m_lkid = ms_in->m_lkid;
	ms->m_result = rv;
	ms->m_nodeid = ret_nodeid;

	error = send_message(mh, ms);
 out:
	return error;
}

/* which args we save from a received message depends heavily on the type
   of message, unlike the send side where we can safely send everything about
   the lkb for any type of message */

static void receive_flags(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	lkb->lkb_exflags = ms->m_exflags;
	lkb->lkb_sbflags = ms->m_sbflags;
	lkb->lkb_flags = (lkb->lkb_flags & 0xFFFF0000) |
		         (ms->m_flags & 0x0000FFFF);
}

static void receive_flags_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	if (ms->m_flags == DLM_IFL_STUB_MS)
		return;

	lkb->lkb_sbflags = ms->m_sbflags;
	lkb->lkb_flags = (lkb->lkb_flags & 0xFFFF0000) |
		         (ms->m_flags & 0x0000FFFF);
}

static int receive_extralen(struct dlm_message *ms)
{
	return (ms->m_header.h_length - sizeof(struct dlm_message));
}

static int receive_lvb(struct dlm_ls *ls, struct dlm_lkb *lkb,
		       struct dlm_message *ms)
{
	int len;

	if (lkb->lkb_exflags & DLM_LKF_VALBLK) {
		if (!lkb->lkb_lvbptr)
			lkb->lkb_lvbptr = dlm_allocate_lvb(ls);
		if (!lkb->lkb_lvbptr)
			return -ENOMEM;
		len = receive_extralen(ms);
		if (len > ls->ls_lvblen)
			len = ls->ls_lvblen;
		memcpy(lkb->lkb_lvbptr, ms->m_extra, len);
	}
	return 0;
}

static void fake_bastfn(void *astparam, int mode)
{
	log_print("fake_bastfn should not be called");
}

static void fake_astfn(void *astparam)
{
	log_print("fake_astfn should not be called");
}

static int receive_request_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
				struct dlm_message *ms)
{
	lkb->lkb_nodeid = ms->m_header.h_nodeid;
	lkb->lkb_ownpid = ms->m_pid;
	lkb->lkb_remid = ms->m_lkid;
	lkb->lkb_grmode = DLM_LOCK_IV;
	lkb->lkb_rqmode = ms->m_rqmode;

	lkb->lkb_bastfn = (ms->m_asts & DLM_CB_BAST) ? &fake_bastfn : NULL;
	lkb->lkb_astfn = (ms->m_asts & DLM_CB_CAST) ? &fake_astfn : NULL;

	if (lkb->lkb_exflags & DLM_LKF_VALBLK) {
		/* lkb was just created so there won't be an lvb yet */
		lkb->lkb_lvbptr = dlm_allocate_lvb(ls);
		if (!lkb->lkb_lvbptr)
			return -ENOMEM;
	}

	return 0;
}

static int receive_convert_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
				struct dlm_message *ms)
{
	if (lkb->lkb_status != DLM_LKSTS_GRANTED)
		return -EBUSY;

	if (receive_lvb(ls, lkb, ms))
		return -ENOMEM;

	lkb->lkb_rqmode = ms->m_rqmode;
	lkb->lkb_lvbseq = ms->m_lvbseq;

	return 0;
}

static int receive_unlock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
			       struct dlm_message *ms)
{
	if (receive_lvb(ls, lkb, ms))
		return -ENOMEM;
	return 0;
}

/* We fill in the stub-lkb fields with the info that send_xxxx_reply()
   uses to send a reply and that the remote end uses to process the reply. */

static void setup_stub_lkb(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb = &ls->ls_stub_lkb;
	lkb->lkb_nodeid = ms->m_header.h_nodeid;
	lkb->lkb_remid = ms->m_lkid;
}

/* This is called after the rsb is locked so that we can safely inspect
   fields in the lkb. */

static int validate_message(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	int from = ms->m_header.h_nodeid;
	int error = 0;

	switch (ms->m_type) {
	case DLM_MSG_CONVERT:
	case DLM_MSG_UNLOCK:
	case DLM_MSG_CANCEL:
		if (!is_master_copy(lkb) || lkb->lkb_nodeid != from)
			error = -EINVAL;
		break;

	case DLM_MSG_CONVERT_REPLY:
	case DLM_MSG_UNLOCK_REPLY:
	case DLM_MSG_CANCEL_REPLY:
	case DLM_MSG_GRANT:
	case DLM_MSG_BAST:
		if (!is_process_copy(lkb) || lkb->lkb_nodeid != from)
			error = -EINVAL;
		break;

	case DLM_MSG_REQUEST_REPLY:
		if (!is_process_copy(lkb))
			error = -EINVAL;
		else if (lkb->lkb_nodeid != -1 && lkb->lkb_nodeid != from)
			error = -EINVAL;
		break;

	default:
		error = -EINVAL;
	}

	if (error)
		log_error(lkb->lkb_resource->res_ls,
			  "ignore invalid message %d from %d %x %x %x %d",
			  ms->m_type, from, lkb->lkb_id, lkb->lkb_remid,
			  lkb->lkb_flags, lkb->lkb_nodeid);
	return error;
}

static void send_repeat_remove(struct dlm_ls *ls, char *ms_name, int len)
{
	char name[DLM_RESNAME_MAXLEN + 1];
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	struct dlm_rsb *r;
	uint32_t hash, b;
	int rv, dir_nodeid;

	memset(name, 0, sizeof(name));
	memcpy(name, ms_name, len);

	hash = jhash(name, len, 0);
	b = hash & (ls->ls_rsbtbl_size - 1);

	dir_nodeid = dlm_hash2nodeid(ls, hash);

	log_error(ls, "send_repeat_remove dir %d %s", dir_nodeid, name);

	spin_lock(&ls->ls_rsbtbl[b].lock);
	rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
	if (!rv) {
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		log_error(ls, "repeat_remove on keep %s", name);
		return;
	}

	rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
	if (!rv) {
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		log_error(ls, "repeat_remove on toss %s", name);
		return;
	}

	/* use ls->remove_name2 to avoid conflict with shrink? */

	spin_lock(&ls->ls_remove_spin);
	ls->ls_remove_len = len;
	memcpy(ls->ls_remove_name, name, DLM_RESNAME_MAXLEN);
	spin_unlock(&ls->ls_remove_spin);
	spin_unlock(&ls->ls_rsbtbl[b].lock);

	rv = _create_message(ls, sizeof(struct dlm_message) + len,
			     dir_nodeid, DLM_MSG_REMOVE, &ms, &mh);
	if (rv)
		return;

	memcpy(ms->m_extra, name, len);
	ms->m_hash = hash;

	send_message(mh, ms);

	spin_lock(&ls->ls_remove_spin);
	ls->ls_remove_len = 0;
	memset(ls->ls_remove_name, 0, DLM_RESNAME_MAXLEN);
	spin_unlock(&ls->ls_remove_spin);
}

static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int from_nodeid;
	int error, namelen = 0;

	from_nodeid = ms->m_header.h_nodeid;

	error = create_lkb(ls, &lkb);
	if (error)
		goto fail;

	receive_flags(lkb, ms);
	lkb->lkb_flags |= DLM_IFL_MSTCPY;
	error = receive_request_args(ls, lkb, ms);
	if (error) {
		__put_lkb(ls, lkb);
		goto fail;
	}

	/* The dir node is the authority on whether we are the master
	   for this rsb or not, so if the master sends us a request, we should
	   recreate the rsb if we've destroyed it.   This race happens when we
	   send a remove message to the dir node at the same time that the dir
	   node sends us a request for the rsb. */

	namelen = receive_extralen(ms);

	error = find_rsb(ls, ms->m_extra, namelen, from_nodeid,
			 R_RECEIVE_REQUEST, &r);
	if (error) {
		__put_lkb(ls, lkb);
		goto fail;
	}

	lock_rsb(r);

	if (r->res_master_nodeid != dlm_our_nodeid()) {
		error = validate_master_nodeid(ls, r, from_nodeid);
		if (error) {
			unlock_rsb(r);
			put_rsb(r);
			__put_lkb(ls, lkb);
			goto fail;
		}
	}

	attach_lkb(r, lkb);
	error = do_request(r, lkb);
	send_request_reply(r, lkb, error);
	do_request_effects(r, lkb, error);

	unlock_rsb(r);
	put_rsb(r);

	if (error == -EINPROGRESS)
		error = 0;
	if (error)
		dlm_put_lkb(lkb);
	return 0;

 fail:
	/* TODO: instead of returning ENOTBLK, add the lkb to res_lookup
	   and do this receive_request again from process_lookup_list once
	   we get the lookup reply.  This would avoid a many repeated
	   ENOTBLK request failures when the lookup reply designating us
	   as master is delayed. */

	/* We could repeatedly return -EBADR here if our send_remove() is
	   delayed in being sent/arriving/being processed on the dir node.
	   Another node would repeatedly lookup up the master, and the dir
	   node would continue returning our nodeid until our send_remove
	   took effect.

	   We send another remove message in case our previous send_remove
	   was lost/ignored/missed somehow. */

	if (error != -ENOTBLK) {
		log_limit(ls, "receive_request %x from %d %d",
			  ms->m_lkid, from_nodeid, error);
	}

	if (namelen && error == -EBADR) {
		send_repeat_remove(ls, ms->m_extra, namelen);
		msleep(1000);
	}

	setup_stub_lkb(ls, ms);
	send_request_reply(&ls->ls_stub_rsb, &ls->ls_stub_lkb, error);
	return error;
}

static int receive_convert(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error, reply = 1;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		goto fail;

	if (lkb->lkb_remid != ms->m_lkid) {
		log_error(ls, "receive_convert %x remid %x recover_seq %llu "
			  "remote %d %x", lkb->lkb_id, lkb->lkb_remid,
			  (unsigned long long)lkb->lkb_recover_seq,
			  ms->m_header.h_nodeid, ms->m_lkid);
		error = -ENOENT;
		dlm_put_lkb(lkb);
		goto fail;
	}

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	receive_flags(lkb, ms);

	error = receive_convert_args(ls, lkb, ms);
	if (error) {
		send_convert_reply(r, lkb, error);
		goto out;
	}

	reply = !down_conversion(lkb);

	error = do_convert(r, lkb);
	if (reply)
		send_convert_reply(r, lkb, error);
	do_convert_effects(r, lkb, error);
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
	return 0;

 fail:
	setup_stub_lkb(ls, ms);
	send_convert_reply(&ls->ls_stub_rsb, &ls->ls_stub_lkb, error);
	return error;
}

static int receive_unlock(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		goto fail;

	if (lkb->lkb_remid != ms->m_lkid) {
		log_error(ls, "receive_unlock %x remid %x remote %d %x",
			  lkb->lkb_id, lkb->lkb_remid,
			  ms->m_header.h_nodeid, ms->m_lkid);
		error = -ENOENT;
		dlm_put_lkb(lkb);
		goto fail;
	}

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	receive_flags(lkb, ms);

	error = receive_unlock_args(ls, lkb, ms);
	if (error) {
		send_unlock_reply(r, lkb, error);
		goto out;
	}

	error = do_unlock(r, lkb);
	send_unlock_reply(r, lkb, error);
	do_unlock_effects(r, lkb, error);
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
	return 0;

 fail:
	setup_stub_lkb(ls, ms);
	send_unlock_reply(&ls->ls_stub_rsb, &ls->ls_stub_lkb, error);
	return error;
}

static int receive_cancel(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		goto fail;

	receive_flags(lkb, ms);

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	error = do_cancel(r, lkb);
	send_cancel_reply(r, lkb, error);
	do_cancel_effects(r, lkb, error);
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
	return 0;

 fail:
	setup_stub_lkb(ls, ms);
	send_cancel_reply(&ls->ls_stub_rsb, &ls->ls_stub_lkb, error);
	return error;
}

static int receive_grant(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		return error;

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	receive_flags_reply(lkb, ms);
	if (is_altmode(lkb))
		munge_altmode(lkb, ms);
	grant_lock_pc(r, lkb, ms);
	queue_cast(r, lkb, 0);
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
	return 0;
}

static int receive_bast(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		return error;

	r = lkb->lkb_resource;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	queue_bast(r, lkb, ms->m_bastmode);
	lkb->lkb_highbast = ms->m_bastmode;
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
	return 0;
}

static void receive_lookup(struct dlm_ls *ls, struct dlm_message *ms)
{
	int len, error, ret_nodeid, from_nodeid, our_nodeid;

	from_nodeid = ms->m_header.h_nodeid;
	our_nodeid = dlm_our_nodeid();

	len = receive_extralen(ms);

	error = dlm_master_lookup(ls, from_nodeid, ms->m_extra, len, 0,
				  &ret_nodeid, NULL);

	/* Optimization: we're master so treat lookup as a request */
	if (!error && ret_nodeid == our_nodeid) {
		receive_request(ls, ms);
		return;
	}
	send_lookup_reply(ls, ms, ret_nodeid, error);
}

static void receive_remove(struct dlm_ls *ls, struct dlm_message *ms)
{
	char name[DLM_RESNAME_MAXLEN+1];
	struct dlm_rsb *r;
	uint32_t hash, b;
	int rv, len, dir_nodeid, from_nodeid;

	from_nodeid = ms->m_header.h_nodeid;

	len = receive_extralen(ms);

	if (len > DLM_RESNAME_MAXLEN) {
		log_error(ls, "receive_remove from %d bad len %d",
			  from_nodeid, len);
		return;
	}

	dir_nodeid = dlm_hash2nodeid(ls, ms->m_hash);
	if (dir_nodeid != dlm_our_nodeid()) {
		log_error(ls, "receive_remove from %d bad nodeid %d",
			  from_nodeid, dir_nodeid);
		return;
	}

	/* Look for name on rsbtbl.toss, if it's there, kill it.
	   If it's on rsbtbl.keep, it's being used, and we should ignore this
	   message.  This is an expected race between the dir node sending a
	   request to the master node at the same time as the master node sends
	   a remove to the dir node.  The resolution to that race is for the
	   dir node to ignore the remove message, and the master node to
	   recreate the master rsb when it gets a request from the dir node for
	   an rsb it doesn't have. */

	memset(name, 0, sizeof(name));
	memcpy(name, ms->m_extra, len);

	hash = jhash(name, len, 0);
	b = hash & (ls->ls_rsbtbl_size - 1);

	spin_lock(&ls->ls_rsbtbl[b].lock);

	rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, &r);
	if (rv) {
		/* verify the rsb is on keep list per comment above */
		rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, &r);
		if (rv) {
			/* should not happen */
			log_error(ls, "receive_remove from %d not found %s",
				  from_nodeid, name);
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			return;
		}
		if (r->res_master_nodeid != from_nodeid) {
			/* should not happen */
			log_error(ls, "receive_remove keep from %d master %d",
				  from_nodeid, r->res_master_nodeid);
			dlm_print_rsb(r);
			spin_unlock(&ls->ls_rsbtbl[b].lock);
			return;
		}

		log_debug(ls, "receive_remove from %d master %d first %x %s",
			  from_nodeid, r->res_master_nodeid, r->res_first_lkid,
			  name);
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		return;
	}

	if (r->res_master_nodeid != from_nodeid) {
		log_error(ls, "receive_remove toss from %d master %d",
			  from_nodeid, r->res_master_nodeid);
		dlm_print_rsb(r);
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		return;
	}

	if (kref_put(&r->res_ref, kill_rsb)) {
		rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
		spin_unlock(&ls->ls_rsbtbl[b].lock);
		dlm_free_rsb(r);
	} else {
		log_error(ls, "receive_remove from %d rsb ref error",
			  from_nodeid);
		dlm_print_rsb(r);
		spin_unlock(&ls->ls_rsbtbl[b].lock);
	}
}

static void receive_purge(struct dlm_ls *ls, struct dlm_message *ms)
{
	do_purge(ls, ms->m_nodeid, ms->m_pid);
}

static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error, mstype, result;
	int from_nodeid = ms->m_header.h_nodeid;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		return error;

	r = lkb->lkb_resource;
	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	mstype = lkb->lkb_wait_type;
	error = remove_from_waiters(lkb, DLM_MSG_REQUEST_REPLY);
	if (error) {
		log_error(ls, "receive_request_reply %x remote %d %x result %d",
			  lkb->lkb_id, from_nodeid, ms->m_lkid, ms->m_result);
		dlm_dump_rsb(r);
		goto out;
	}

	/* Optimization: the dir node was also the master, so it took our
	   lookup as a request and sent request reply instead of lookup reply */
	if (mstype == DLM_MSG_LOOKUP) {
		r->res_master_nodeid = from_nodeid;
		r->res_nodeid = from_nodeid;
		lkb->lkb_nodeid = from_nodeid;
	}

	/* this is the value returned from do_request() on the master */
	result = ms->m_result;

	switch (result) {
	case -EAGAIN:
		/* request would block (be queued) on remote master */
		queue_cast(r, lkb, -EAGAIN);
		confirm_master(r, -EAGAIN);
		unhold_lkb(lkb); /* undoes create_lkb() */
		break;

	case -EINPROGRESS:
	case 0:
		/* request was queued or granted on remote master */
		receive_flags_reply(lkb, ms);
		lkb->lkb_remid = ms->m_lkid;
		if (is_altmode(lkb))
			munge_altmode(lkb, ms);
		if (result) {
			add_lkb(r, lkb, DLM_LKSTS_WAITING);
			add_timeout(lkb);
		} else {
			grant_lock_pc(r, lkb, ms);
			queue_cast(r, lkb, 0);
		}
		confirm_master(r, result);
		break;

	case -EBADR:
	case -ENOTBLK:
		/* find_rsb failed to find rsb or rsb wasn't master */
		log_limit(ls, "receive_request_reply %x from %d %d "
			  "master %d dir %d first %x %s", lkb->lkb_id,
			  from_nodeid, result, r->res_master_nodeid,
			  r->res_dir_nodeid, r->res_first_lkid, r->res_name);

		if (r->res_dir_nodeid != dlm_our_nodeid() &&
		    r->res_master_nodeid != dlm_our_nodeid()) {
			/* cause _request_lock->set_master->send_lookup */
			r->res_master_nodeid = 0;
			r->res_nodeid = -1;
			lkb->lkb_nodeid = -1;
		}

		if (is_overlap(lkb)) {
			/* we'll ignore error in cancel/unlock reply */
			queue_cast_overlap(r, lkb);
			confirm_master(r, result);
			unhold_lkb(lkb); /* undoes create_lkb() */
		} else {
			_request_lock(r, lkb);

			if (r->res_master_nodeid == dlm_our_nodeid())
				confirm_master(r, 0);
		}
		break;

	default:
		log_error(ls, "receive_request_reply %x error %d",
			  lkb->lkb_id, result);
	}

	if (is_overlap_unlock(lkb) && (result == 0 || result == -EINPROGRESS)) {
		log_debug(ls, "receive_request_reply %x result %d unlock",
			  lkb->lkb_id, result);
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
		send_unlock(r, lkb);
	} else if (is_overlap_cancel(lkb) && (result == -EINPROGRESS)) {
		log_debug(ls, "receive_request_reply %x cancel", lkb->lkb_id);
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
		send_cancel(r, lkb);
	} else {
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
	}
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
	return 0;
}

static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
				    struct dlm_message *ms)
{
	/* this is the value returned from do_convert() on the master */
	switch (ms->m_result) {
	case -EAGAIN:
		/* convert would block (be queued) on remote master */
		queue_cast(r, lkb, -EAGAIN);
		break;

	case -EDEADLK:
		receive_flags_reply(lkb, ms);
		revert_lock_pc(r, lkb);
		queue_cast(r, lkb, -EDEADLK);
		break;

	case -EINPROGRESS:
		/* convert was queued on remote master */
		receive_flags_reply(lkb, ms);
		if (is_demoted(lkb))
			munge_demoted(lkb);
		del_lkb(r, lkb);
		add_lkb(r, lkb, DLM_LKSTS_CONVERT);
		add_timeout(lkb);
		break;

	case 0:
		/* convert was granted on remote master */
		receive_flags_reply(lkb, ms);
		if (is_demoted(lkb))
			munge_demoted(lkb);
		grant_lock_pc(r, lkb, ms);
		queue_cast(r, lkb, 0);
		break;

	default:
		log_error(r->res_ls, "receive_convert_reply %x remote %d %x %d",
			  lkb->lkb_id, ms->m_header.h_nodeid, ms->m_lkid,
			  ms->m_result);
		dlm_print_rsb(r);
		dlm_print_lkb(lkb);
	}
}

static void _receive_convert_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	struct dlm_rsb *r = lkb->lkb_resource;
	int error;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	/* stub reply can happen with waiters_mutex held */
	error = remove_from_waiters_ms(lkb, ms);
	if (error)
		goto out;

	__receive_convert_reply(r, lkb, ms);
 out:
	unlock_rsb(r);
	put_rsb(r);
}

static int receive_convert_reply(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		return error;

	_receive_convert_reply(lkb, ms);
	dlm_put_lkb(lkb);
	return 0;
}

static void _receive_unlock_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	struct dlm_rsb *r = lkb->lkb_resource;
	int error;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	/* stub reply can happen with waiters_mutex held */
	error = remove_from_waiters_ms(lkb, ms);
	if (error)
		goto out;

	/* this is the value returned from do_unlock() on the master */

	switch (ms->m_result) {
	case -DLM_EUNLOCK:
		receive_flags_reply(lkb, ms);
		remove_lock_pc(r, lkb);
		queue_cast(r, lkb, -DLM_EUNLOCK);
		break;
	case -ENOENT:
		break;
	default:
		log_error(r->res_ls, "receive_unlock_reply %x error %d",
			  lkb->lkb_id, ms->m_result);
	}
 out:
	unlock_rsb(r);
	put_rsb(r);
}

static int receive_unlock_reply(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		return error;

	_receive_unlock_reply(lkb, ms);
	dlm_put_lkb(lkb);
	return 0;
}

static void _receive_cancel_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
{
	struct dlm_rsb *r = lkb->lkb_resource;
	int error;

	hold_rsb(r);
	lock_rsb(r);

	error = validate_message(lkb, ms);
	if (error)
		goto out;

	/* stub reply can happen with waiters_mutex held */
	error = remove_from_waiters_ms(lkb, ms);
	if (error)
		goto out;

	/* this is the value returned from do_cancel() on the master */

	switch (ms->m_result) {
	case -DLM_ECANCEL:
		receive_flags_reply(lkb, ms);
		revert_lock_pc(r, lkb);
		queue_cast(r, lkb, -DLM_ECANCEL);
		break;
	case 0:
		break;
	default:
		log_error(r->res_ls, "receive_cancel_reply %x error %d",
			  lkb->lkb_id, ms->m_result);
	}
 out:
	unlock_rsb(r);
	put_rsb(r);
}

static int receive_cancel_reply(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	int error;

	error = find_lkb(ls, ms->m_remid, &lkb);
	if (error)
		return error;

	_receive_cancel_reply(lkb, ms);
	dlm_put_lkb(lkb);
	return 0;
}

static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error, ret_nodeid;
	int do_lookup_list = 0;

	error = find_lkb(ls, ms->m_lkid, &lkb);
	if (error) {
		log_error(ls, "receive_lookup_reply no lkid %x", ms->m_lkid);
		return;
	}

	/* ms->m_result is the value returned by dlm_master_lookup on dir node
	   FIXME: will a non-zero error ever be returned? */

	r = lkb->lkb_resource;
	hold_rsb(r);
	lock_rsb(r);

	error = remove_from_waiters(lkb, DLM_MSG_LOOKUP_REPLY);
	if (error)
		goto out;

	ret_nodeid = ms->m_nodeid;

	/* We sometimes receive a request from the dir node for this
	   rsb before we've received the dir node's loookup_reply for it.
	   The request from the dir node implies we're the master, so we set
	   ourself as master in receive_request_reply, and verify here that
	   we are indeed the master. */

	if (r->res_master_nodeid && (r->res_master_nodeid != ret_nodeid)) {
		/* This should never happen */
		log_error(ls, "receive_lookup_reply %x from %d ret %d "
			  "master %d dir %d our %d first %x %s",
			  lkb->lkb_id, ms->m_header.h_nodeid, ret_nodeid,
			  r->res_master_nodeid, r->res_dir_nodeid,
			  dlm_our_nodeid(), r->res_first_lkid, r->res_name);
	}

	if (ret_nodeid == dlm_our_nodeid()) {
		r->res_master_nodeid = ret_nodeid;
		r->res_nodeid = 0;
		do_lookup_list = 1;
		r->res_first_lkid = 0;
	} else if (ret_nodeid == -1) {
		/* the remote node doesn't believe it's the dir node */
		log_error(ls, "receive_lookup_reply %x from %d bad ret_nodeid",
			  lkb->lkb_id, ms->m_header.h_nodeid);
		r->res_master_nodeid = 0;
		r->res_nodeid = -1;
		lkb->lkb_nodeid = -1;
	} else {
		/* set_master() will set lkb_nodeid from r */
		r->res_master_nodeid = ret_nodeid;
		r->res_nodeid = ret_nodeid;
	}

	if (is_overlap(lkb)) {
		log_debug(ls, "receive_lookup_reply %x unlock %x",
			  lkb->lkb_id, lkb->lkb_flags);
		queue_cast_overlap(r, lkb);
		unhold_lkb(lkb); /* undoes create_lkb() */
		goto out_list;
	}

	_request_lock(r, lkb);

 out_list:
	if (do_lookup_list)
		process_lookup_list(r);
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);
}

static void _receive_message(struct dlm_ls *ls, struct dlm_message *ms,
			     uint32_t saved_seq)
{
	int error = 0, noent = 0;

	if (!dlm_is_member(ls, ms->m_header.h_nodeid)) {
		log_limit(ls, "receive %d from non-member %d %x %x %d",
			  ms->m_type, ms->m_header.h_nodeid, ms->m_lkid,
			  ms->m_remid, ms->m_result);
		return;
	}

	switch (ms->m_type) {

	/* messages sent to a master node */

	case DLM_MSG_REQUEST:
		error = receive_request(ls, ms);
		break;

	case DLM_MSG_CONVERT:
		error = receive_convert(ls, ms);
		break;

	case DLM_MSG_UNLOCK:
		error = receive_unlock(ls, ms);
		break;

	case DLM_MSG_CANCEL:
		noent = 1;
		error = receive_cancel(ls, ms);
		break;

	/* messages sent from a master node (replies to above) */

	case DLM_MSG_REQUEST_REPLY:
		error = receive_request_reply(ls, ms);
		break;

	case DLM_MSG_CONVERT_REPLY:
		error = receive_convert_reply(ls, ms);
		break;

	case DLM_MSG_UNLOCK_REPLY:
		error = receive_unlock_reply(ls, ms);
		break;

	case DLM_MSG_CANCEL_REPLY:
		error = receive_cancel_reply(ls, ms);
		break;

	/* messages sent from a master node (only two types of async msg) */

	case DLM_MSG_GRANT:
		noent = 1;
		error = receive_grant(ls, ms);
		break;

	case DLM_MSG_BAST:
		noent = 1;
		error = receive_bast(ls, ms);
		break;

	/* messages sent to a dir node */

	case DLM_MSG_LOOKUP:
		receive_lookup(ls, ms);
		break;

	case DLM_MSG_REMOVE:
		receive_remove(ls, ms);
		break;

	/* messages sent from a dir node (remove has no reply) */

	case DLM_MSG_LOOKUP_REPLY:
		receive_lookup_reply(ls, ms);
		break;

	/* other messages */

	case DLM_MSG_PURGE:
		receive_purge(ls, ms);
		break;

	default:
		log_error(ls, "unknown message type %d", ms->m_type);
	}

	/*
	 * When checking for ENOENT, we're checking the result of
	 * find_lkb(m_remid):
	 *
	 * The lock id referenced in the message wasn't found.  This may
	 * happen in normal usage for the async messages and cancel, so
	 * only use log_debug for them.
	 *
	 * Some errors are expected and normal.
	 */

	if (error == -ENOENT && noent) {
		log_debug(ls, "receive %d no %x remote %d %x saved_seq %u",
			  ms->m_type, ms->m_remid, ms->m_header.h_nodeid,
			  ms->m_lkid, saved_seq);
	} else if (error == -ENOENT) {
		log_error(ls, "receive %d no %x remote %d %x saved_seq %u",
			  ms->m_type, ms->m_remid, ms->m_header.h_nodeid,
			  ms->m_lkid, saved_seq);

		if (ms->m_type == DLM_MSG_CONVERT)
			dlm_dump_rsb_hash(ls, ms->m_hash);
	}

	if (error == -EINVAL) {
		log_error(ls, "receive %d inval from %d lkid %x remid %x "
			  "saved_seq %u",
			  ms->m_type, ms->m_header.h_nodeid,
			  ms->m_lkid, ms->m_remid, saved_seq);
	}
}

/* If the lockspace is in recovery mode (locking stopped), then normal
   messages are saved on the requestqueue for processing after recovery is
   done.  When not in recovery mode, we wait for dlm_recoverd to drain saved
   messages off the requestqueue before we process new ones. This occurs right
   after recovery completes when we transition from saving all messages on
   requestqueue, to processing all the saved messages, to processing new
   messages as they arrive. */

static void dlm_receive_message(struct dlm_ls *ls, struct dlm_message *ms,
				int nodeid)
{
	if (dlm_locking_stopped(ls)) {
		/* If we were a member of this lockspace, left, and rejoined,
		   other nodes may still be sending us messages from the
		   lockspace generation before we left. */
		if (!ls->ls_generation) {
			log_limit(ls, "receive %d from %d ignore old gen",
				  ms->m_type, nodeid);
			return;
		}

		dlm_add_requestqueue(ls, nodeid, ms);
	} else {
		dlm_wait_requestqueue(ls);
		_receive_message(ls, ms, 0);
	}
}

/* This is called by dlm_recoverd to process messages that were saved on
   the requestqueue. */

void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms,
			       uint32_t saved_seq)
{
	_receive_message(ls, ms, saved_seq);
}

/* This is called by the midcomms layer when something is received for
   the lockspace.  It could be either a MSG (normal message sent as part of
   standard locking activity) or an RCOM (recovery message sent as part of
   lockspace recovery). */

void dlm_receive_buffer(union dlm_packet *p, int nodeid)
{
	struct dlm_header *hd = &p->header;
	struct dlm_ls *ls;
	int type = 0;

	switch (hd->h_cmd) {
	case DLM_MSG:
		dlm_message_in(&p->message);
		type = p->message.m_type;
		break;
	case DLM_RCOM:
		dlm_rcom_in(&p->rcom);
		type = p->rcom.rc_type;
		break;
	default:
		log_print("invalid h_cmd %d from %u", hd->h_cmd, nodeid);
		return;
	}

	if (hd->h_nodeid != nodeid) {
		log_print("invalid h_nodeid %d from %d lockspace %x",
			  hd->h_nodeid, nodeid, hd->h_lockspace);
		return;
	}

	ls = dlm_find_lockspace_global(hd->h_lockspace);
	if (!ls) {
		if (dlm_config.ci_log_debug) {
			printk_ratelimited(KERN_DEBUG "dlm: invalid lockspace "
				"%u from %d cmd %d type %d\n",
				hd->h_lockspace, nodeid, hd->h_cmd, type);
		}

		if (hd->h_cmd == DLM_RCOM && type == DLM_RCOM_STATUS)
			dlm_send_ls_not_ready(nodeid, &p->rcom);
		return;
	}

	/* this rwsem allows dlm_ls_stop() to wait for all dlm_recv threads to
	   be inactive (in this ls) before transitioning to recovery mode */

	down_read(&ls->ls_recv_active);
	if (hd->h_cmd == DLM_MSG)
		dlm_receive_message(ls, &p->message, nodeid);
	else
		dlm_receive_rcom(ls, &p->rcom, nodeid);
	up_read(&ls->ls_recv_active);

	dlm_put_lockspace(ls);
}

static void recover_convert_waiter(struct dlm_ls *ls, struct dlm_lkb *lkb,
				   struct dlm_message *ms_stub)
{
	if (middle_conversion(lkb)) {
		hold_lkb(lkb);
		memset(ms_stub, 0, sizeof(struct dlm_message));
		ms_stub->m_flags = DLM_IFL_STUB_MS;
		ms_stub->m_type = DLM_MSG_CONVERT_REPLY;
		ms_stub->m_result = -EINPROGRESS;
		ms_stub->m_header.h_nodeid = lkb->lkb_nodeid;
		_receive_convert_reply(lkb, ms_stub);

		/* Same special case as in receive_rcom_lock_args() */
		lkb->lkb_grmode = DLM_LOCK_IV;
		rsb_set_flag(lkb->lkb_resource, RSB_RECOVER_CONVERT);
		unhold_lkb(lkb);

	} else if (lkb->lkb_rqmode >= lkb->lkb_grmode) {
		lkb->lkb_flags |= DLM_IFL_RESEND;
	}

	/* lkb->lkb_rqmode < lkb->lkb_grmode shouldn't happen since down
	   conversions are async; there's no reply from the remote master */
}

/* A waiting lkb needs recovery if the master node has failed, or
   the master node is changing (only when no directory is used) */

static int waiter_needs_recovery(struct dlm_ls *ls, struct dlm_lkb *lkb,
				 int dir_nodeid)
{
	if (dlm_no_directory(ls))
		return 1;

	if (dlm_is_removed(ls, lkb->lkb_wait_nodeid))
		return 1;

	return 0;
}

/* Recovery for locks that are waiting for replies from nodes that are now
   gone.  We can just complete unlocks and cancels by faking a reply from the
   dead node.  Requests and up-conversions we flag to be resent after
   recovery.  Down-conversions can just be completed with a fake reply like
   unlocks.  Conversions between PR and CW need special attention. */

void dlm_recover_waiters_pre(struct dlm_ls *ls)
{
	struct dlm_lkb *lkb, *safe;
	struct dlm_message *ms_stub;
	int wait_type, stub_unlock_result, stub_cancel_result;
	int dir_nodeid;

	ms_stub = kmalloc(sizeof(*ms_stub), GFP_KERNEL);
	if (!ms_stub)
		return;

	mutex_lock(&ls->ls_waiters_mutex);

	list_for_each_entry_safe(lkb, safe, &ls->ls_waiters, lkb_wait_reply) {

		dir_nodeid = dlm_dir_nodeid(lkb->lkb_resource);

		/* exclude debug messages about unlocks because there can be so
		   many and they aren't very interesting */

		if (lkb->lkb_wait_type != DLM_MSG_UNLOCK) {
			log_debug(ls, "waiter %x remote %x msg %d r_nodeid %d "
				  "lkb_nodeid %d wait_nodeid %d dir_nodeid %d",
				  lkb->lkb_id,
				  lkb->lkb_remid,
				  lkb->lkb_wait_type,
				  lkb->lkb_resource->res_nodeid,
				  lkb->lkb_nodeid,
				  lkb->lkb_wait_nodeid,
				  dir_nodeid);
		}

		/* all outstanding lookups, regardless of destination  will be
		   resent after recovery is done */

		if (lkb->lkb_wait_type == DLM_MSG_LOOKUP) {
			lkb->lkb_flags |= DLM_IFL_RESEND;
			continue;
		}

		if (!waiter_needs_recovery(ls, lkb, dir_nodeid))
			continue;

		wait_type = lkb->lkb_wait_type;
		stub_unlock_result = -DLM_EUNLOCK;
		stub_cancel_result = -DLM_ECANCEL;

		/* Main reply may have been received leaving a zero wait_type,
		   but a reply for the overlapping op may not have been
		   received.  In that case we need to fake the appropriate
		   reply for the overlap op. */

		if (!wait_type) {
			if (is_overlap_cancel(lkb)) {
				wait_type = DLM_MSG_CANCEL;
				if (lkb->lkb_grmode == DLM_LOCK_IV)
					stub_cancel_result = 0;
			}
			if (is_overlap_unlock(lkb)) {
				wait_type = DLM_MSG_UNLOCK;
				if (lkb->lkb_grmode == DLM_LOCK_IV)
					stub_unlock_result = -ENOENT;
			}

			log_debug(ls, "rwpre overlap %x %x %d %d %d",
				  lkb->lkb_id, lkb->lkb_flags, wait_type,
				  stub_cancel_result, stub_unlock_result);
		}

		switch (wait_type) {

		case DLM_MSG_REQUEST:
			lkb->lkb_flags |= DLM_IFL_RESEND;
			break;

		case DLM_MSG_CONVERT:
			recover_convert_waiter(ls, lkb, ms_stub);
			break;

		case DLM_MSG_UNLOCK:
			hold_lkb(lkb);
			memset(ms_stub, 0, sizeof(struct dlm_message));
			ms_stub->m_flags = DLM_IFL_STUB_MS;
			ms_stub->m_type = DLM_MSG_UNLOCK_REPLY;
			ms_stub->m_result = stub_unlock_result;
			ms_stub->m_header.h_nodeid = lkb->lkb_nodeid;
			_receive_unlock_reply(lkb, ms_stub);
			dlm_put_lkb(lkb);
			break;

		case DLM_MSG_CANCEL:
			hold_lkb(lkb);
			memset(ms_stub, 0, sizeof(struct dlm_message));
			ms_stub->m_flags = DLM_IFL_STUB_MS;
			ms_stub->m_type = DLM_MSG_CANCEL_REPLY;
			ms_stub->m_result = stub_cancel_result;
			ms_stub->m_header.h_nodeid = lkb->lkb_nodeid;
			_receive_cancel_reply(lkb, ms_stub);
			dlm_put_lkb(lkb);
			break;

		default:
			log_error(ls, "invalid lkb wait_type %d %d",
				  lkb->lkb_wait_type, wait_type);
		}
		schedule();
	}
	mutex_unlock(&ls->ls_waiters_mutex);
	kfree(ms_stub);
}

static struct dlm_lkb *find_resend_waiter(struct dlm_ls *ls)
{
	struct dlm_lkb *lkb;
	int found = 0;

	mutex_lock(&ls->ls_waiters_mutex);
	list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
		if (lkb->lkb_flags & DLM_IFL_RESEND) {
			hold_lkb(lkb);
			found = 1;
			break;
		}
	}
	mutex_unlock(&ls->ls_waiters_mutex);

	if (!found)
		lkb = NULL;
	return lkb;
}

/* Deal with lookups and lkb's marked RESEND from _pre.  We may now be the
   master or dir-node for r.  Processing the lkb may result in it being placed
   back on waiters. */

/* We do this after normal locking has been enabled and any saved messages
   (in requestqueue) have been processed.  We should be confident that at
   this point we won't get or process a reply to any of these waiting
   operations.  But, new ops may be coming in on the rsbs/locks here from
   userspace or remotely. */

/* there may have been an overlap unlock/cancel prior to recovery or after
   recovery.  if before, the lkb may still have a pos wait_count; if after, the
   overlap flag would just have been set and nothing new sent.  we can be
   confident here than any replies to either the initial op or overlap ops
   prior to recovery have been received. */

int dlm_recover_waiters_post(struct dlm_ls *ls)
{
	struct dlm_lkb *lkb;
	struct dlm_rsb *r;
	int error = 0, mstype, err, oc, ou;

	while (1) {
		if (dlm_locking_stopped(ls)) {
			log_debug(ls, "recover_waiters_post aborted");
			error = -EINTR;
			break;
		}

		lkb = find_resend_waiter(ls);
		if (!lkb)
			break;

		r = lkb->lkb_resource;
		hold_rsb(r);
		lock_rsb(r);

		mstype = lkb->lkb_wait_type;
		oc = is_overlap_cancel(lkb);
		ou = is_overlap_unlock(lkb);
		err = 0;

		log_debug(ls, "waiter %x remote %x msg %d r_nodeid %d "
			  "lkb_nodeid %d wait_nodeid %d dir_nodeid %d "
			  "overlap %d %d", lkb->lkb_id, lkb->lkb_remid, mstype,
			  r->res_nodeid, lkb->lkb_nodeid, lkb->lkb_wait_nodeid,
			  dlm_dir_nodeid(r), oc, ou);

		/* At this point we assume that we won't get a reply to any
		   previous op or overlap op on this lock.  First, do a big
		   remove_from_waiters() for all previous ops. */

		lkb->lkb_flags &= ~DLM_IFL_RESEND;
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
		lkb->lkb_wait_type = 0;
		lkb->lkb_wait_count = 0;
		mutex_lock(&ls->ls_waiters_mutex);
		list_del_init(&lkb->lkb_wait_reply);
		mutex_unlock(&ls->ls_waiters_mutex);
		unhold_lkb(lkb); /* for waiters list */

		if (oc || ou) {
			/* do an unlock or cancel instead of resending */
			switch (mstype) {
			case DLM_MSG_LOOKUP:
			case DLM_MSG_REQUEST:
				queue_cast(r, lkb, ou ? -DLM_EUNLOCK :
							-DLM_ECANCEL);
				unhold_lkb(lkb); /* undoes create_lkb() */
				break;
			case DLM_MSG_CONVERT:
				if (oc) {
					queue_cast(r, lkb, -DLM_ECANCEL);
				} else {
					lkb->lkb_exflags |= DLM_LKF_FORCEUNLOCK;
					_unlock_lock(r, lkb);
				}
				break;
			default:
				err = 1;
			}
		} else {
			switch (mstype) {
			case DLM_MSG_LOOKUP:
			case DLM_MSG_REQUEST:
				_request_lock(r, lkb);
				if (is_master(r))
					confirm_master(r, 0);
				break;
			case DLM_MSG_CONVERT:
				_convert_lock(r, lkb);
				break;
			default:
				err = 1;
			}
		}

		if (err) {
			log_error(ls, "waiter %x msg %d r_nodeid %d "
				  "dir_nodeid %d overlap %d %d",
				  lkb->lkb_id, mstype, r->res_nodeid,
				  dlm_dir_nodeid(r), oc, ou);
		}
		unlock_rsb(r);
		put_rsb(r);
		dlm_put_lkb(lkb);
	}

	return error;
}

static void purge_mstcpy_list(struct dlm_ls *ls, struct dlm_rsb *r,
			      struct list_head *list)
{
	struct dlm_lkb *lkb, *safe;

	list_for_each_entry_safe(lkb, safe, list, lkb_statequeue) {
		if (!is_master_copy(lkb))
			continue;

		/* don't purge lkbs we've added in recover_master_copy for
		   the current recovery seq */

		if (lkb->lkb_recover_seq == ls->ls_recover_seq)
			continue;

		del_lkb(r, lkb);

		/* this put should free the lkb */
		if (!dlm_put_lkb(lkb))
			log_error(ls, "purged mstcpy lkb not released");
	}
}

void dlm_purge_mstcpy_locks(struct dlm_rsb *r)
{
	struct dlm_ls *ls = r->res_ls;

	purge_mstcpy_list(ls, r, &r->res_grantqueue);
	purge_mstcpy_list(ls, r, &r->res_convertqueue);
	purge_mstcpy_list(ls, r, &r->res_waitqueue);
}

static void purge_dead_list(struct dlm_ls *ls, struct dlm_rsb *r,
			    struct list_head *list,
			    int nodeid_gone, unsigned int *count)
{
	struct dlm_lkb *lkb, *safe;

	list_for_each_entry_safe(lkb, safe, list, lkb_statequeue) {
		if (!is_master_copy(lkb))
			continue;

		if ((lkb->lkb_nodeid == nodeid_gone) ||
		    dlm_is_removed(ls, lkb->lkb_nodeid)) {

			/* tell recover_lvb to invalidate the lvb
			   because a node holding EX/PW failed */
			if ((lkb->lkb_exflags & DLM_LKF_VALBLK) &&
			    (lkb->lkb_grmode >= DLM_LOCK_PW)) {
				rsb_set_flag(r, RSB_RECOVER_LVB_INVAL);
			}

			del_lkb(r, lkb);

			/* this put should free the lkb */
			if (!dlm_put_lkb(lkb))
				log_error(ls, "purged dead lkb not released");

			rsb_set_flag(r, RSB_RECOVER_GRANT);

			(*count)++;
		}
	}
}

/* Get rid of locks held by nodes that are gone. */

void dlm_recover_purge(struct dlm_ls *ls)
{
	struct dlm_rsb *r;
	struct dlm_member *memb;
	int nodes_count = 0;
	int nodeid_gone = 0;
	unsigned int lkb_count = 0;

	/* cache one removed nodeid to optimize the common
	   case of a single node removed */

	list_for_each_entry(memb, &ls->ls_nodes_gone, list) {
		nodes_count++;
		nodeid_gone = memb->nodeid;
	}

	if (!nodes_count)
		return;

	down_write(&ls->ls_root_sem);
	list_for_each_entry(r, &ls->ls_root_list, res_root_list) {
		hold_rsb(r);
		lock_rsb(r);
		if (is_master(r)) {
			purge_dead_list(ls, r, &r->res_grantqueue,
					nodeid_gone, &lkb_count);
			purge_dead_list(ls, r, &r->res_convertqueue,
					nodeid_gone, &lkb_count);
			purge_dead_list(ls, r, &r->res_waitqueue,
					nodeid_gone, &lkb_count);
		}
		unlock_rsb(r);
		unhold_rsb(r);
		cond_resched();
	}
	up_write(&ls->ls_root_sem);

	if (lkb_count)
		log_rinfo(ls, "dlm_recover_purge %u locks for %u nodes",
			  lkb_count, nodes_count);
}

static struct dlm_rsb *find_grant_rsb(struct dlm_ls *ls, int bucket)
{
	struct rb_node *n;
	struct dlm_rsb *r;

	spin_lock(&ls->ls_rsbtbl[bucket].lock);
	for (n = rb_first(&ls->ls_rsbtbl[bucket].keep); n; n = rb_next(n)) {
		r = rb_entry(n, struct dlm_rsb, res_hashnode);

		if (!rsb_flag(r, RSB_RECOVER_GRANT))
			continue;
		if (!is_master(r)) {
			rsb_clear_flag(r, RSB_RECOVER_GRANT);
			continue;
		}
		hold_rsb(r);
		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
		return r;
	}
	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
	return NULL;
}

/*
 * Attempt to grant locks on resources that we are the master of.
 * Locks may have become grantable during recovery because locks
 * from departed nodes have been purged (or not rebuilt), allowing
 * previously blocked locks to now be granted.  The subset of rsb's
 * we are interested in are those with lkb's on either the convert or
 * waiting queues.
 *
 * Simplest would be to go through each master rsb and check for non-empty
 * convert or waiting queues, and attempt to grant on those rsbs.
 * Checking the queues requires lock_rsb, though, for which we'd need
 * to release the rsbtbl lock.  This would make iterating through all
 * rsb's very inefficient.  So, we rely on earlier recovery routines
 * to set RECOVER_GRANT on any rsb's that we should attempt to grant
 * locks for.
 */

void dlm_recover_grant(struct dlm_ls *ls)
{
	struct dlm_rsb *r;
	int bucket = 0;
	unsigned int count = 0;
	unsigned int rsb_count = 0;
	unsigned int lkb_count = 0;

	while (1) {
		r = find_grant_rsb(ls, bucket);
		if (!r) {
			if (bucket == ls->ls_rsbtbl_size - 1)
				break;
			bucket++;
			continue;
		}
		rsb_count++;
		count = 0;
		lock_rsb(r);
		/* the RECOVER_GRANT flag is checked in the grant path */
		grant_pending_locks(r, &count);
		rsb_clear_flag(r, RSB_RECOVER_GRANT);
		lkb_count += count;
		confirm_master(r, 0);
		unlock_rsb(r);
		put_rsb(r);
		cond_resched();
	}

	if (lkb_count)
		log_rinfo(ls, "dlm_recover_grant %u locks on %u resources",
			  lkb_count, rsb_count);
}

static struct dlm_lkb *search_remid_list(struct list_head *head, int nodeid,
					 uint32_t remid)
{
	struct dlm_lkb *lkb;

	list_for_each_entry(lkb, head, lkb_statequeue) {
		if (lkb->lkb_nodeid == nodeid && lkb->lkb_remid == remid)
			return lkb;
	}
	return NULL;
}

static struct dlm_lkb *search_remid(struct dlm_rsb *r, int nodeid,
				    uint32_t remid)
{
	struct dlm_lkb *lkb;

	lkb = search_remid_list(&r->res_grantqueue, nodeid, remid);
	if (lkb)
		return lkb;
	lkb = search_remid_list(&r->res_convertqueue, nodeid, remid);
	if (lkb)
		return lkb;
	lkb = search_remid_list(&r->res_waitqueue, nodeid, remid);
	if (lkb)
		return lkb;
	return NULL;
}

/* needs at least dlm_rcom + rcom_lock */
static int receive_rcom_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
				  struct dlm_rsb *r, struct dlm_rcom *rc)
{
	struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;

	lkb->lkb_nodeid = rc->rc_header.h_nodeid;
	lkb->lkb_ownpid = le32_to_cpu(rl->rl_ownpid);
	lkb->lkb_remid = le32_to_cpu(rl->rl_lkid);
	lkb->lkb_exflags = le32_to_cpu(rl->rl_exflags);
	lkb->lkb_flags = le32_to_cpu(rl->rl_flags) & 0x0000FFFF;
	lkb->lkb_flags |= DLM_IFL_MSTCPY;
	lkb->lkb_lvbseq = le32_to_cpu(rl->rl_lvbseq);
	lkb->lkb_rqmode = rl->rl_rqmode;
	lkb->lkb_grmode = rl->rl_grmode;
	/* don't set lkb_status because add_lkb wants to itself */

	lkb->lkb_bastfn = (rl->rl_asts & DLM_CB_BAST) ? &fake_bastfn : NULL;
	lkb->lkb_astfn = (rl->rl_asts & DLM_CB_CAST) ? &fake_astfn : NULL;

	if (lkb->lkb_exflags & DLM_LKF_VALBLK) {
		int lvblen = rc->rc_header.h_length - sizeof(struct dlm_rcom) -
			 sizeof(struct rcom_lock);
		if (lvblen > ls->ls_lvblen)
			return -EINVAL;
		lkb->lkb_lvbptr = dlm_allocate_lvb(ls);
		if (!lkb->lkb_lvbptr)
			return -ENOMEM;
		memcpy(lkb->lkb_lvbptr, rl->rl_lvb, lvblen);
	}

	/* Conversions between PR and CW (middle modes) need special handling.
	   The real granted mode of these converting locks cannot be determined
	   until all locks have been rebuilt on the rsb (recover_conversion) */

	if (rl->rl_wait_type == cpu_to_le16(DLM_MSG_CONVERT) &&
	    middle_conversion(lkb)) {
		rl->rl_status = DLM_LKSTS_CONVERT;
		lkb->lkb_grmode = DLM_LOCK_IV;
		rsb_set_flag(r, RSB_RECOVER_CONVERT);
	}

	return 0;
}

/* This lkb may have been recovered in a previous aborted recovery so we need
   to check if the rsb already has an lkb with the given remote nodeid/lkid.
   If so we just send back a standard reply.  If not, we create a new lkb with
   the given values and send back our lkid.  We send back our lkid by sending
   back the rcom_lock struct we got but with the remid field filled in. */

/* needs at least dlm_rcom + rcom_lock */
int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
{
	struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;
	struct dlm_rsb *r;
	struct dlm_lkb *lkb;
	uint32_t remid = 0;
	int from_nodeid = rc->rc_header.h_nodeid;
	int error;

	if (rl->rl_parent_lkid) {
		error = -EOPNOTSUPP;
		goto out;
	}

	remid = le32_to_cpu(rl->rl_lkid);

	/* In general we expect the rsb returned to be R_MASTER, but we don't
	   have to require it.  Recovery of masters on one node can overlap
	   recovery of locks on another node, so one node can send us MSTCPY
	   locks before we've made ourselves master of this rsb.  We can still
	   add new MSTCPY locks that we receive here without any harm; when
	   we make ourselves master, dlm_recover_masters() won't touch the
	   MSTCPY locks we've received early. */

	error = find_rsb(ls, rl->rl_name, le16_to_cpu(rl->rl_namelen),
			 from_nodeid, R_RECEIVE_RECOVER, &r);
	if (error)
		goto out;

	lock_rsb(r);

	if (dlm_no_directory(ls) && (dlm_dir_nodeid(r) != dlm_our_nodeid())) {
		log_error(ls, "dlm_recover_master_copy remote %d %x not dir",
			  from_nodeid, remid);
		error = -EBADR;
		goto out_unlock;
	}

	lkb = search_remid(r, from_nodeid, remid);
	if (lkb) {
		error = -EEXIST;
		goto out_remid;
	}

	error = create_lkb(ls, &lkb);
	if (error)
		goto out_unlock;

	error = receive_rcom_lock_args(ls, lkb, r, rc);
	if (error) {
		__put_lkb(ls, lkb);
		goto out_unlock;
	}

	attach_lkb(r, lkb);
	add_lkb(r, lkb, rl->rl_status);
	error = 0;
	ls->ls_recover_locks_in++;

	if (!list_empty(&r->res_waitqueue) || !list_empty(&r->res_convertqueue))
		rsb_set_flag(r, RSB_RECOVER_GRANT);

 out_remid:
	/* this is the new value returned to the lock holder for
	   saving in its process-copy lkb */
	rl->rl_remid = cpu_to_le32(lkb->lkb_id);

	lkb->lkb_recover_seq = ls->ls_recover_seq;

 out_unlock:
	unlock_rsb(r);
	put_rsb(r);
 out:
	if (error && error != -EEXIST)
		log_rinfo(ls, "dlm_recover_master_copy remote %d %x error %d",
			  from_nodeid, remid, error);
	rl->rl_result = cpu_to_le32(error);
	return error;
}

/* needs at least dlm_rcom + rcom_lock */
int dlm_recover_process_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
{
	struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;
	struct dlm_rsb *r;
	struct dlm_lkb *lkb;
	uint32_t lkid, remid;
	int error, result;

	lkid = le32_to_cpu(rl->rl_lkid);
	remid = le32_to_cpu(rl->rl_remid);
	result = le32_to_cpu(rl->rl_result);

	error = find_lkb(ls, lkid, &lkb);
	if (error) {
		log_error(ls, "dlm_recover_process_copy no %x remote %d %x %d",
			  lkid, rc->rc_header.h_nodeid, remid, result);
		return error;
	}

	r = lkb->lkb_resource;
	hold_rsb(r);
	lock_rsb(r);

	if (!is_process_copy(lkb)) {
		log_error(ls, "dlm_recover_process_copy bad %x remote %d %x %d",
			  lkid, rc->rc_header.h_nodeid, remid, result);
		dlm_dump_rsb(r);
		unlock_rsb(r);
		put_rsb(r);
		dlm_put_lkb(lkb);
		return -EINVAL;
	}

	switch (result) {
	case -EBADR:
		/* There's a chance the new master received our lock before
		   dlm_recover_master_reply(), this wouldn't happen if we did
		   a barrier between recover_masters and recover_locks. */

		log_debug(ls, "dlm_recover_process_copy %x remote %d %x %d",
			  lkid, rc->rc_header.h_nodeid, remid, result);
	
		dlm_send_rcom_lock(r, lkb);
		goto out;
	case -EEXIST:
	case 0:
		lkb->lkb_remid = remid;
		break;
	default:
		log_error(ls, "dlm_recover_process_copy %x remote %d %x %d unk",
			  lkid, rc->rc_header.h_nodeid, remid, result);
	}

	/* an ack for dlm_recover_locks() which waits for replies from
	   all the locks it sends to new masters */
	dlm_recovered_lock(r);
 out:
	unlock_rsb(r);
	put_rsb(r);
	dlm_put_lkb(lkb);

	return 0;
}

int dlm_user_request(struct dlm_ls *ls, struct dlm_user_args *ua,
		     int mode, uint32_t flags, void *name, unsigned int namelen,
		     unsigned long timeout_cs)
{
	struct dlm_lkb *lkb;
	struct dlm_args args;
	int error;

	dlm_lock_recovery(ls);

	error = create_lkb(ls, &lkb);
	if (error) {
		kfree(ua);
		goto out;
	}

	if (flags & DLM_LKF_VALBLK) {
		ua->lksb.sb_lvbptr = kzalloc(DLM_USER_LVB_LEN, GFP_NOFS);
		if (!ua->lksb.sb_lvbptr) {
			kfree(ua);
			__put_lkb(ls, lkb);
			error = -ENOMEM;
			goto out;
		}
	}
	error = set_lock_args(mode, &ua->lksb, flags, namelen, timeout_cs,
			      fake_astfn, ua, fake_bastfn, &args);
	if (error) {
		kfree(ua->lksb.sb_lvbptr);
		ua->lksb.sb_lvbptr = NULL;
		kfree(ua);
		__put_lkb(ls, lkb);
		goto out;
	}

	/* After ua is attached to lkb it will be freed by dlm_free_lkb().
	   When DLM_IFL_USER is set, the dlm knows that this is a userspace
	   lock and that lkb_astparam is the dlm_user_args structure. */
	lkb->lkb_flags |= DLM_IFL_USER;
	error = request_lock(ls, lkb, name, namelen, &args);

	switch (error) {
	case 0:
		break;
	case -EINPROGRESS:
		error = 0;
		break;
	case -EAGAIN:
		error = 0;
		fallthrough;
	default:
		__put_lkb(ls, lkb);
		goto out;
	}

	/* add this new lkb to the per-process list of locks */
	spin_lock(&ua->proc->locks_spin);
	hold_lkb(lkb);
	list_add_tail(&lkb->lkb_ownqueue, &ua->proc->locks);
	spin_unlock(&ua->proc->locks_spin);
 out:
	dlm_unlock_recovery(ls);
	return error;
}

int dlm_user_convert(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
		     int mode, uint32_t flags, uint32_t lkid, char *lvb_in,
		     unsigned long timeout_cs)
{
	struct dlm_lkb *lkb;
	struct dlm_args args;
	struct dlm_user_args *ua;
	int error;

	dlm_lock_recovery(ls);

	error = find_lkb(ls, lkid, &lkb);
	if (error)
		goto out;

	/* user can change the params on its lock when it converts it, or
	   add an lvb that didn't exist before */

	ua = lkb->lkb_ua;

	if (flags & DLM_LKF_VALBLK && !ua->lksb.sb_lvbptr) {
		ua->lksb.sb_lvbptr = kzalloc(DLM_USER_LVB_LEN, GFP_NOFS);
		if (!ua->lksb.sb_lvbptr) {
			error = -ENOMEM;
			goto out_put;
		}
	}
	if (lvb_in && ua->lksb.sb_lvbptr)
		memcpy(ua->lksb.sb_lvbptr, lvb_in, DLM_USER_LVB_LEN);

	ua->xid = ua_tmp->xid;
	ua->castparam = ua_tmp->castparam;
	ua->castaddr = ua_tmp->castaddr;
	ua->bastparam = ua_tmp->bastparam;
	ua->bastaddr = ua_tmp->bastaddr;
	ua->user_lksb = ua_tmp->user_lksb;

	error = set_lock_args(mode, &ua->lksb, flags, 0, timeout_cs,
			      fake_astfn, ua, fake_bastfn, &args);
	if (error)
		goto out_put;

	error = convert_lock(ls, lkb, &args);

	if (error == -EINPROGRESS || error == -EAGAIN || error == -EDEADLK)
		error = 0;
 out_put:
	dlm_put_lkb(lkb);
 out:
	dlm_unlock_recovery(ls);
	kfree(ua_tmp);
	return error;
}

/*
 * The caller asks for an orphan lock on a given resource with a given mode.
 * If a matching lock exists, it's moved to the owner's list of locks and
 * the lkid is returned.
 */

int dlm_user_adopt_orphan(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
		     int mode, uint32_t flags, void *name, unsigned int namelen,
		     unsigned long timeout_cs, uint32_t *lkid)
{
	struct dlm_lkb *lkb;
	struct dlm_user_args *ua;
	int found_other_mode = 0;
	int found = 0;
	int rv = 0;

	mutex_lock(&ls->ls_orphans_mutex);
	list_for_each_entry(lkb, &ls->ls_orphans, lkb_ownqueue) {
		if (lkb->lkb_resource->res_length != namelen)
			continue;
		if (memcmp(lkb->lkb_resource->res_name, name, namelen))
			continue;
		if (lkb->lkb_grmode != mode) {
			found_other_mode = 1;
			continue;
		}

		found = 1;
		list_del_init(&lkb->lkb_ownqueue);
		lkb->lkb_flags &= ~DLM_IFL_ORPHAN;
		*lkid = lkb->lkb_id;
		break;
	}
	mutex_unlock(&ls->ls_orphans_mutex);

	if (!found && found_other_mode) {
		rv = -EAGAIN;
		goto out;
	}

	if (!found) {
		rv = -ENOENT;
		goto out;
	}

	lkb->lkb_exflags = flags;
	lkb->lkb_ownpid = (int) current->pid;

	ua = lkb->lkb_ua;

	ua->proc = ua_tmp->proc;
	ua->xid = ua_tmp->xid;
	ua->castparam = ua_tmp->castparam;
	ua->castaddr = ua_tmp->castaddr;
	ua->bastparam = ua_tmp->bastparam;
	ua->bastaddr = ua_tmp->bastaddr;
	ua->user_lksb = ua_tmp->user_lksb;

	/*
	 * The lkb reference from the ls_orphans list was not
	 * removed above, and is now considered the reference
	 * for the proc locks list.
	 */

	spin_lock(&ua->proc->locks_spin);
	list_add_tail(&lkb->lkb_ownqueue, &ua->proc->locks);
	spin_unlock(&ua->proc->locks_spin);
 out:
	kfree(ua_tmp);
	return rv;
}

int dlm_user_unlock(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
		    uint32_t flags, uint32_t lkid, char *lvb_in)
{
	struct dlm_lkb *lkb;
	struct dlm_args args;
	struct dlm_user_args *ua;
	int error;

	dlm_lock_recovery(ls);

	error = find_lkb(ls, lkid, &lkb);
	if (error)
		goto out;

	ua = lkb->lkb_ua;

	if (lvb_in && ua->lksb.sb_lvbptr)
		memcpy(ua->lksb.sb_lvbptr, lvb_in, DLM_USER_LVB_LEN);
	if (ua_tmp->castparam)
		ua->castparam = ua_tmp->castparam;
	ua->user_lksb = ua_tmp->user_lksb;

	error = set_unlock_args(flags, ua, &args);
	if (error)
		goto out_put;

	error = unlock_lock(ls, lkb, &args);

	if (error == -DLM_EUNLOCK)
		error = 0;
	/* from validate_unlock_args() */
	if (error == -EBUSY && (flags & DLM_LKF_FORCEUNLOCK))
		error = 0;
	if (error)
		goto out_put;

	spin_lock(&ua->proc->locks_spin);
	/* dlm_user_add_cb() may have already taken lkb off the proc list */
	if (!list_empty(&lkb->lkb_ownqueue))
		list_move(&lkb->lkb_ownqueue, &ua->proc->unlocking);
	spin_unlock(&ua->proc->locks_spin);
 out_put:
	dlm_put_lkb(lkb);
 out:
	dlm_unlock_recovery(ls);
	kfree(ua_tmp);
	return error;
}

int dlm_user_cancel(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
		    uint32_t flags, uint32_t lkid)
{
	struct dlm_lkb *lkb;
	struct dlm_args args;
	struct dlm_user_args *ua;
	int error;

	dlm_lock_recovery(ls);

	error = find_lkb(ls, lkid, &lkb);
	if (error)
		goto out;

	ua = lkb->lkb_ua;
	if (ua_tmp->castparam)
		ua->castparam = ua_tmp->castparam;
	ua->user_lksb = ua_tmp->user_lksb;

	error = set_unlock_args(flags, ua, &args);
	if (error)
		goto out_put;

	error = cancel_lock(ls, lkb, &args);

	if (error == -DLM_ECANCEL)
		error = 0;
	/* from validate_unlock_args() */
	if (error == -EBUSY)
		error = 0;
 out_put:
	dlm_put_lkb(lkb);
 out:
	dlm_unlock_recovery(ls);
	kfree(ua_tmp);
	return error;
}

int dlm_user_deadlock(struct dlm_ls *ls, uint32_t flags, uint32_t lkid)
{
	struct dlm_lkb *lkb;
	struct dlm_args args;
	struct dlm_user_args *ua;
	struct dlm_rsb *r;
	int error;

	dlm_lock_recovery(ls);

	error = find_lkb(ls, lkid, &lkb);
	if (error)
		goto out;

	ua = lkb->lkb_ua;

	error = set_unlock_args(flags, ua, &args);
	if (error)
		goto out_put;

	/* same as cancel_lock(), but set DEADLOCK_CANCEL after lock_rsb */

	r = lkb->lkb_resource;
	hold_rsb(r);
	lock_rsb(r);

	error = validate_unlock_args(lkb, &args);
	if (error)
		goto out_r;
	lkb->lkb_flags |= DLM_IFL_DEADLOCK_CANCEL;

	error = _cancel_lock(r, lkb);
 out_r:
	unlock_rsb(r);
	put_rsb(r);

	if (error == -DLM_ECANCEL)
		error = 0;
	/* from validate_unlock_args() */
	if (error == -EBUSY)
		error = 0;
 out_put:
	dlm_put_lkb(lkb);
 out:
	dlm_unlock_recovery(ls);
	return error;
}

/* lkb's that are removed from the waiters list by revert are just left on the
   orphans list with the granted orphan locks, to be freed by purge */

static int orphan_proc_lock(struct dlm_ls *ls, struct dlm_lkb *lkb)
{
	struct dlm_args args;
	int error;

	hold_lkb(lkb); /* reference for the ls_orphans list */
	mutex_lock(&ls->ls_orphans_mutex);
	list_add_tail(&lkb->lkb_ownqueue, &ls->ls_orphans);
	mutex_unlock(&ls->ls_orphans_mutex);

	set_unlock_args(0, lkb->lkb_ua, &args);

	error = cancel_lock(ls, lkb, &args);
	if (error == -DLM_ECANCEL)
		error = 0;
	return error;
}

/* The FORCEUNLOCK flag allows the unlock to go ahead even if the lkb isn't
   granted.  Regardless of what rsb queue the lock is on, it's removed and
   freed.  The IVVALBLK flag causes the lvb on the resource to be invalidated
   if our lock is PW/EX (it's ignored if our granted mode is smaller.) */

static int unlock_proc_lock(struct dlm_ls *ls, struct dlm_lkb *lkb)
{
	struct dlm_args args;
	int error;

	set_unlock_args(DLM_LKF_FORCEUNLOCK | DLM_LKF_IVVALBLK,
			lkb->lkb_ua, &args);

	error = unlock_lock(ls, lkb, &args);
	if (error == -DLM_EUNLOCK)
		error = 0;
	return error;
}

/* We have to release clear_proc_locks mutex before calling unlock_proc_lock()
   (which does lock_rsb) due to deadlock with receiving a message that does
   lock_rsb followed by dlm_user_add_cb() */

static struct dlm_lkb *del_proc_lock(struct dlm_ls *ls,
				     struct dlm_user_proc *proc)
{
	struct dlm_lkb *lkb = NULL;

	mutex_lock(&ls->ls_clear_proc_locks);
	if (list_empty(&proc->locks))
		goto out;

	lkb = list_entry(proc->locks.next, struct dlm_lkb, lkb_ownqueue);
	list_del_init(&lkb->lkb_ownqueue);

	if (lkb->lkb_exflags & DLM_LKF_PERSISTENT)
		lkb->lkb_flags |= DLM_IFL_ORPHAN;
	else
		lkb->lkb_flags |= DLM_IFL_DEAD;
 out:
	mutex_unlock(&ls->ls_clear_proc_locks);
	return lkb;
}

/* The ls_clear_proc_locks mutex protects against dlm_user_add_cb() which
   1) references lkb->ua which we free here and 2) adds lkbs to proc->asts,
   which we clear here. */

/* proc CLOSING flag is set so no more device_reads should look at proc->asts
   list, and no more device_writes should add lkb's to proc->locks list; so we
   shouldn't need to take asts_spin or locks_spin here.  this assumes that
   device reads/writes/closes are serialized -- FIXME: we may need to serialize
   them ourself. */

void dlm_clear_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc)
{
	struct dlm_lkb *lkb, *safe;

	dlm_lock_recovery(ls);

	while (1) {
		lkb = del_proc_lock(ls, proc);
		if (!lkb)
			break;
		del_timeout(lkb);
		if (lkb->lkb_exflags & DLM_LKF_PERSISTENT)
			orphan_proc_lock(ls, lkb);
		else
			unlock_proc_lock(ls, lkb);

		/* this removes the reference for the proc->locks list
		   added by dlm_user_request, it may result in the lkb
		   being freed */

		dlm_put_lkb(lkb);
	}

	mutex_lock(&ls->ls_clear_proc_locks);

	/* in-progress unlocks */
	list_for_each_entry_safe(lkb, safe, &proc->unlocking, lkb_ownqueue) {
		list_del_init(&lkb->lkb_ownqueue);
		lkb->lkb_flags |= DLM_IFL_DEAD;
		dlm_put_lkb(lkb);
	}

	list_for_each_entry_safe(lkb, safe, &proc->asts, lkb_cb_list) {
		memset(&lkb->lkb_callbacks, 0,
		       sizeof(struct dlm_callback) * DLM_CALLBACKS_SIZE);
		list_del_init(&lkb->lkb_cb_list);
		dlm_put_lkb(lkb);
	}

	mutex_unlock(&ls->ls_clear_proc_locks);
	dlm_unlock_recovery(ls);
}

static void purge_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc)
{
	struct dlm_lkb *lkb, *safe;

	while (1) {
		lkb = NULL;
		spin_lock(&proc->locks_spin);
		if (!list_empty(&proc->locks)) {
			lkb = list_entry(proc->locks.next, struct dlm_lkb,
					 lkb_ownqueue);
			list_del_init(&lkb->lkb_ownqueue);
		}
		spin_unlock(&proc->locks_spin);

		if (!lkb)
			break;

		lkb->lkb_flags |= DLM_IFL_DEAD;
		unlock_proc_lock(ls, lkb);
		dlm_put_lkb(lkb); /* ref from proc->locks list */
	}

	spin_lock(&proc->locks_spin);
	list_for_each_entry_safe(lkb, safe, &proc->unlocking, lkb_ownqueue) {
		list_del_init(&lkb->lkb_ownqueue);
		lkb->lkb_flags |= DLM_IFL_DEAD;
		dlm_put_lkb(lkb);
	}
	spin_unlock(&proc->locks_spin);

	spin_lock(&proc->asts_spin);
	list_for_each_entry_safe(lkb, safe, &proc->asts, lkb_cb_list) {
		memset(&lkb->lkb_callbacks, 0,
		       sizeof(struct dlm_callback) * DLM_CALLBACKS_SIZE);
		list_del_init(&lkb->lkb_cb_list);
		dlm_put_lkb(lkb);
	}
	spin_unlock(&proc->asts_spin);
}

/* pid of 0 means purge all orphans */

static void do_purge(struct dlm_ls *ls, int nodeid, int pid)
{
	struct dlm_lkb *lkb, *safe;

	mutex_lock(&ls->ls_orphans_mutex);
	list_for_each_entry_safe(lkb, safe, &ls->ls_orphans, lkb_ownqueue) {
		if (pid && lkb->lkb_ownpid != pid)
			continue;
		unlock_proc_lock(ls, lkb);
		list_del_init(&lkb->lkb_ownqueue);
		dlm_put_lkb(lkb);
	}
	mutex_unlock(&ls->ls_orphans_mutex);
}

static int send_purge(struct dlm_ls *ls, int nodeid, int pid)
{
	struct dlm_message *ms;
	struct dlm_mhandle *mh;
	int error;

	error = _create_message(ls, sizeof(struct dlm_message), nodeid,
				DLM_MSG_PURGE, &ms, &mh);
	if (error)
		return error;
	ms->m_nodeid = nodeid;
	ms->m_pid = pid;

	return send_message(mh, ms);
}

int dlm_user_purge(struct dlm_ls *ls, struct dlm_user_proc *proc,
		   int nodeid, int pid)
{
	int error = 0;

	if (nodeid && (nodeid != dlm_our_nodeid())) {
		error = send_purge(ls, nodeid, pid);
	} else {
		dlm_lock_recovery(ls);
		if (pid == current->pid)
			purge_proc_locks(ls, proc);
		else
			do_purge(ls, nodeid, pid);
		dlm_unlock_recovery(ls);
	}
	return error;
}