summaryrefslogtreecommitdiffstats
path: root/fs/xfs/xfs_log_recover.c
blob: 7d897c58b0c83fac4a2faf410da5892f4a7363be (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_log.h"
#include "xfs_log_priv.h"
#include "xfs_log_recover.h"
#include "xfs_inode_item.h"
#include "xfs_extfree_item.h"
#include "xfs_trans_priv.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_quota.h"
#include "xfs_cksum.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_bmap_btree.h"
#include "xfs_error.h"
#include "xfs_dir2.h"
#include "xfs_rmap_item.h"
#include "xfs_buf_item.h"
#include "xfs_refcount_item.h"
#include "xfs_bmap_item.h"

#define BLK_AVG(blk1, blk2)	((blk1+blk2) >> 1)

STATIC int
xlog_find_zeroed(
	struct xlog	*,
	xfs_daddr_t	*);
STATIC int
xlog_clear_stale_blocks(
	struct xlog	*,
	xfs_lsn_t);
#if defined(DEBUG)
STATIC void
xlog_recover_check_summary(
	struct xlog *);
#else
#define	xlog_recover_check_summary(log)
#endif
STATIC int
xlog_do_recovery_pass(
        struct xlog *, xfs_daddr_t, xfs_daddr_t, int, xfs_daddr_t *);

/*
 * This structure is used during recovery to record the buf log items which
 * have been canceled and should not be replayed.
 */
struct xfs_buf_cancel {
	xfs_daddr_t		bc_blkno;
	uint			bc_len;
	int			bc_refcount;
	struct list_head	bc_list;
};

/*
 * Sector aligned buffer routines for buffer create/read/write/access
 */

/*
 * Verify the log-relative block number and length in basic blocks are valid for
 * an operation involving the given XFS log buffer. Returns true if the fields
 * are valid, false otherwise.
 */
static inline bool
xlog_verify_bp(
	struct xlog	*log,
	xfs_daddr_t	blk_no,
	int		bbcount)
{
	if (blk_no < 0 || blk_no >= log->l_logBBsize)
		return false;
	if (bbcount <= 0 || (blk_no + bbcount) > log->l_logBBsize)
		return false;
	return true;
}

/*
 * Allocate a buffer to hold log data.  The buffer needs to be able
 * to map to a range of nbblks basic blocks at any valid (basic
 * block) offset within the log.
 */
STATIC xfs_buf_t *
xlog_get_bp(
	struct xlog	*log,
	int		nbblks)
{
	struct xfs_buf	*bp;

	/*
	 * Pass log block 0 since we don't have an addr yet, buffer will be
	 * verified on read.
	 */
	if (!xlog_verify_bp(log, 0, nbblks)) {
		xfs_warn(log->l_mp, "Invalid block length (0x%x) for buffer",
			nbblks);
		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_HIGH, log->l_mp);
		return NULL;
	}

	/*
	 * We do log I/O in units of log sectors (a power-of-2
	 * multiple of the basic block size), so we round up the
	 * requested size to accommodate the basic blocks required
	 * for complete log sectors.
	 *
	 * In addition, the buffer may be used for a non-sector-
	 * aligned block offset, in which case an I/O of the
	 * requested size could extend beyond the end of the
	 * buffer.  If the requested size is only 1 basic block it
	 * will never straddle a sector boundary, so this won't be
	 * an issue.  Nor will this be a problem if the log I/O is
	 * done in basic blocks (sector size 1).  But otherwise we
	 * extend the buffer by one extra log sector to ensure
	 * there's space to accommodate this possibility.
	 */
	if (nbblks > 1 && log->l_sectBBsize > 1)
		nbblks += log->l_sectBBsize;
	nbblks = round_up(nbblks, log->l_sectBBsize);

	bp = xfs_buf_get_uncached(log->l_mp->m_logdev_targp, nbblks, 0);
	if (bp)
		xfs_buf_unlock(bp);
	return bp;
}

STATIC void
xlog_put_bp(
	xfs_buf_t	*bp)
{
	xfs_buf_free(bp);
}

/*
 * Return the address of the start of the given block number's data
 * in a log buffer.  The buffer covers a log sector-aligned region.
 */
STATIC char *
xlog_align(
	struct xlog	*log,
	xfs_daddr_t	blk_no,
	int		nbblks,
	struct xfs_buf	*bp)
{
	xfs_daddr_t	offset = blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1);

	ASSERT(offset + nbblks <= bp->b_length);
	return bp->b_addr + BBTOB(offset);
}


/*
 * nbblks should be uint, but oh well.  Just want to catch that 32-bit length.
 */
STATIC int
xlog_bread_noalign(
	struct xlog	*log,
	xfs_daddr_t	blk_no,
	int		nbblks,
	struct xfs_buf	*bp)
{
	int		error;

	if (!xlog_verify_bp(log, blk_no, nbblks)) {
		xfs_warn(log->l_mp,
			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
			 blk_no, nbblks);
		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_HIGH, log->l_mp);
		return -EFSCORRUPTED;
	}

	blk_no = round_down(blk_no, log->l_sectBBsize);
	nbblks = round_up(nbblks, log->l_sectBBsize);

	ASSERT(nbblks > 0);
	ASSERT(nbblks <= bp->b_length);

	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
	bp->b_flags |= XBF_READ;
	bp->b_io_length = nbblks;
	bp->b_error = 0;

	error = xfs_buf_submit_wait(bp);
	if (error && !XFS_FORCED_SHUTDOWN(log->l_mp))
		xfs_buf_ioerror_alert(bp, __func__);
	return error;
}

STATIC int
xlog_bread(
	struct xlog	*log,
	xfs_daddr_t	blk_no,
	int		nbblks,
	struct xfs_buf	*bp,
	char		**offset)
{
	int		error;

	error = xlog_bread_noalign(log, blk_no, nbblks, bp);
	if (error)
		return error;

	*offset = xlog_align(log, blk_no, nbblks, bp);
	return 0;
}

/*
 * Read at an offset into the buffer. Returns with the buffer in it's original
 * state regardless of the result of the read.
 */
STATIC int
xlog_bread_offset(
	struct xlog	*log,
	xfs_daddr_t	blk_no,		/* block to read from */
	int		nbblks,		/* blocks to read */
	struct xfs_buf	*bp,
	char		*offset)
{
	char		*orig_offset = bp->b_addr;
	int		orig_len = BBTOB(bp->b_length);
	int		error, error2;

	error = xfs_buf_associate_memory(bp, offset, BBTOB(nbblks));
	if (error)
		return error;

	error = xlog_bread_noalign(log, blk_no, nbblks, bp);

	/* must reset buffer pointer even on error */
	error2 = xfs_buf_associate_memory(bp, orig_offset, orig_len);
	if (error)
		return error;
	return error2;
}

/*
 * Write out the buffer at the given block for the given number of blocks.
 * The buffer is kept locked across the write and is returned locked.
 * This can only be used for synchronous log writes.
 */
STATIC int
xlog_bwrite(
	struct xlog	*log,
	xfs_daddr_t	blk_no,
	int		nbblks,
	struct xfs_buf	*bp)
{
	int		error;

	if (!xlog_verify_bp(log, blk_no, nbblks)) {
		xfs_warn(log->l_mp,
			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
			 blk_no, nbblks);
		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_HIGH, log->l_mp);
		return -EFSCORRUPTED;
	}

	blk_no = round_down(blk_no, log->l_sectBBsize);
	nbblks = round_up(nbblks, log->l_sectBBsize);

	ASSERT(nbblks > 0);
	ASSERT(nbblks <= bp->b_length);

	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
	xfs_buf_hold(bp);
	xfs_buf_lock(bp);
	bp->b_io_length = nbblks;
	bp->b_error = 0;

	error = xfs_bwrite(bp);
	if (error)
		xfs_buf_ioerror_alert(bp, __func__);
	xfs_buf_relse(bp);
	return error;
}

#ifdef DEBUG
/*
 * dump debug superblock and log record information
 */
STATIC void
xlog_header_check_dump(
	xfs_mount_t		*mp,
	xlog_rec_header_t	*head)
{
	xfs_debug(mp, "%s:  SB : uuid = %pU, fmt = %d",
		__func__, &mp->m_sb.sb_uuid, XLOG_FMT);
	xfs_debug(mp, "    log : uuid = %pU, fmt = %d",
		&head->h_fs_uuid, be32_to_cpu(head->h_fmt));
}
#else
#define xlog_header_check_dump(mp, head)
#endif

/*
 * check log record header for recovery
 */
STATIC int
xlog_header_check_recover(
	xfs_mount_t		*mp,
	xlog_rec_header_t	*head)
{
	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));

	/*
	 * IRIX doesn't write the h_fmt field and leaves it zeroed
	 * (XLOG_FMT_UNKNOWN). This stops us from trying to recover
	 * a dirty log created in IRIX.
	 */
	if (unlikely(head->h_fmt != cpu_to_be32(XLOG_FMT))) {
		xfs_warn(mp,
	"dirty log written in incompatible format - can't recover");
		xlog_header_check_dump(mp, head);
		XFS_ERROR_REPORT("xlog_header_check_recover(1)",
				 XFS_ERRLEVEL_HIGH, mp);
		return -EFSCORRUPTED;
	} else if (unlikely(!uuid_equal(&mp->m_sb.sb_uuid, &head->h_fs_uuid))) {
		xfs_warn(mp,
	"dirty log entry has mismatched uuid - can't recover");
		xlog_header_check_dump(mp, head);
		XFS_ERROR_REPORT("xlog_header_check_recover(2)",
				 XFS_ERRLEVEL_HIGH, mp);
		return -EFSCORRUPTED;
	}
	return 0;
}

/*
 * read the head block of the log and check the header
 */
STATIC int
xlog_header_check_mount(
	xfs_mount_t		*mp,
	xlog_rec_header_t	*head)
{
	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));

	if (uuid_is_null(&head->h_fs_uuid)) {
		/*
		 * IRIX doesn't write the h_fs_uuid or h_fmt fields. If
		 * h_fs_uuid is null, we assume this log was last mounted
		 * by IRIX and continue.
		 */
		xfs_warn(mp, "null uuid in log - IRIX style log");
	} else if (unlikely(!uuid_equal(&mp->m_sb.sb_uuid, &head->h_fs_uuid))) {
		xfs_warn(mp, "log has mismatched uuid - can't recover");
		xlog_header_check_dump(mp, head);
		XFS_ERROR_REPORT("xlog_header_check_mount",
				 XFS_ERRLEVEL_HIGH, mp);
		return -EFSCORRUPTED;
	}
	return 0;
}

STATIC void
xlog_recover_iodone(
	struct xfs_buf	*bp)
{
	if (bp->b_error) {
		/*
		 * We're not going to bother about retrying
		 * this during recovery. One strike!
		 */
		if (!XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
			xfs_buf_ioerror_alert(bp, __func__);
			xfs_force_shutdown(bp->b_target->bt_mount,
						SHUTDOWN_META_IO_ERROR);
		}
	}

	/*
	 * On v5 supers, a bli could be attached to update the metadata LSN.
	 * Clean it up.
	 */
	if (bp->b_log_item)
		xfs_buf_item_relse(bp);
	ASSERT(bp->b_log_item == NULL);

	bp->b_iodone = NULL;
	xfs_buf_ioend(bp);
}

/*
 * This routine finds (to an approximation) the first block in the physical
 * log which contains the given cycle.  It uses a binary search algorithm.
 * Note that the algorithm can not be perfect because the disk will not
 * necessarily be perfect.
 */
STATIC int
xlog_find_cycle_start(
	struct xlog	*log,
	struct xfs_buf	*bp,
	xfs_daddr_t	first_blk,
	xfs_daddr_t	*last_blk,
	uint		cycle)
{
	char		*offset;
	xfs_daddr_t	mid_blk;
	xfs_daddr_t	end_blk;
	uint		mid_cycle;
	int		error;

	end_blk = *last_blk;
	mid_blk = BLK_AVG(first_blk, end_blk);
	while (mid_blk != first_blk && mid_blk != end_blk) {
		error = xlog_bread(log, mid_blk, 1, bp, &offset);
		if (error)
			return error;
		mid_cycle = xlog_get_cycle(offset);
		if (mid_cycle == cycle)
			end_blk = mid_blk;   /* last_half_cycle == mid_cycle */
		else
			first_blk = mid_blk; /* first_half_cycle == mid_cycle */
		mid_blk = BLK_AVG(first_blk, end_blk);
	}
	ASSERT((mid_blk == first_blk && mid_blk+1 == end_blk) ||
	       (mid_blk == end_blk && mid_blk-1 == first_blk));

	*last_blk = end_blk;

	return 0;
}

/*
 * Check that a range of blocks does not contain stop_on_cycle_no.
 * Fill in *new_blk with the block offset where such a block is
 * found, or with -1 (an invalid block number) if there is no such
 * block in the range.  The scan needs to occur from front to back
 * and the pointer into the region must be updated since a later
 * routine will need to perform another test.
 */
STATIC int
xlog_find_verify_cycle(
	struct xlog	*log,
	xfs_daddr_t	start_blk,
	int		nbblks,
	uint		stop_on_cycle_no,
	xfs_daddr_t	*new_blk)
{
	xfs_daddr_t	i, j;
	uint		cycle;
	xfs_buf_t	*bp;
	xfs_daddr_t	bufblks;
	char		*buf = NULL;
	int		error = 0;

	/*
	 * Greedily allocate a buffer big enough to handle the full
	 * range of basic blocks we'll be examining.  If that fails,
	 * try a smaller size.  We need to be able to read at least
	 * a log sector, or we're out of luck.
	 */
	bufblks = 1 << ffs(nbblks);
	while (bufblks > log->l_logBBsize)
		bufblks >>= 1;
	while (!(bp = xlog_get_bp(log, bufblks))) {
		bufblks >>= 1;
		if (bufblks < log->l_sectBBsize)
			return -ENOMEM;
	}

	for (i = start_blk; i < start_blk + nbblks; i += bufblks) {
		int	bcount;

		bcount = min(bufblks, (start_blk + nbblks - i));

		error = xlog_bread(log, i, bcount, bp, &buf);
		if (error)
			goto out;

		for (j = 0; j < bcount; j++) {
			cycle = xlog_get_cycle(buf);
			if (cycle == stop_on_cycle_no) {
				*new_blk = i+j;
				goto out;
			}

			buf += BBSIZE;
		}
	}

	*new_blk = -1;

out:
	xlog_put_bp(bp);
	return error;
}

/*
 * Potentially backup over partial log record write.
 *
 * In the typical case, last_blk is the number of the block directly after
 * a good log record.  Therefore, we subtract one to get the block number
 * of the last block in the given buffer.  extra_bblks contains the number
 * of blocks we would have read on a previous read.  This happens when the
 * last log record is split over the end of the physical log.
 *
 * extra_bblks is the number of blocks potentially verified on a previous
 * call to this routine.
 */
STATIC int
xlog_find_verify_log_record(
	struct xlog		*log,
	xfs_daddr_t		start_blk,
	xfs_daddr_t		*last_blk,
	int			extra_bblks)
{
	xfs_daddr_t		i;
	xfs_buf_t		*bp;
	char			*offset = NULL;
	xlog_rec_header_t	*head = NULL;
	int			error = 0;
	int			smallmem = 0;
	int			num_blks = *last_blk - start_blk;
	int			xhdrs;

	ASSERT(start_blk != 0 || *last_blk != start_blk);

	if (!(bp = xlog_get_bp(log, num_blks))) {
		if (!(bp = xlog_get_bp(log, 1)))
			return -ENOMEM;
		smallmem = 1;
	} else {
		error = xlog_bread(log, start_blk, num_blks, bp, &offset);
		if (error)
			goto out;
		offset += ((num_blks - 1) << BBSHIFT);
	}

	for (i = (*last_blk) - 1; i >= 0; i--) {
		if (i < start_blk) {
			/* valid log record not found */
			xfs_warn(log->l_mp,
		"Log inconsistent (didn't find previous header)");
			ASSERT(0);
			error = -EIO;
			goto out;
		}

		if (smallmem) {
			error = xlog_bread(log, i, 1, bp, &offset);
			if (error)
				goto out;
		}

		head = (xlog_rec_header_t *)offset;

		if (head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
			break;

		if (!smallmem)
			offset -= BBSIZE;
	}

	/*
	 * We hit the beginning of the physical log & still no header.  Return
	 * to caller.  If caller can handle a return of -1, then this routine
	 * will be called again for the end of the physical log.
	 */
	if (i == -1) {
		error = 1;
		goto out;
	}

	/*
	 * We have the final block of the good log (the first block
	 * of the log record _before_ the head. So we check the uuid.
	 */
	if ((error = xlog_header_check_mount(log->l_mp, head)))
		goto out;

	/*
	 * We may have found a log record header before we expected one.
	 * last_blk will be the 1st block # with a given cycle #.  We may end
	 * up reading an entire log record.  In this case, we don't want to
	 * reset last_blk.  Only when last_blk points in the middle of a log
	 * record do we update last_blk.
	 */
	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
		uint	h_size = be32_to_cpu(head->h_size);

		xhdrs = h_size / XLOG_HEADER_CYCLE_SIZE;
		if (h_size % XLOG_HEADER_CYCLE_SIZE)
			xhdrs++;
	} else {
		xhdrs = 1;
	}

	if (*last_blk - i + extra_bblks !=
	    BTOBB(be32_to_cpu(head->h_len)) + xhdrs)
		*last_blk = i;

out:
	xlog_put_bp(bp);
	return error;
}

/*
 * Head is defined to be the point of the log where the next log write
 * could go.  This means that incomplete LR writes at the end are
 * eliminated when calculating the head.  We aren't guaranteed that previous
 * LR have complete transactions.  We only know that a cycle number of
 * current cycle number -1 won't be present in the log if we start writing
 * from our current block number.
 *
 * last_blk contains the block number of the first block with a given
 * cycle number.
 *
 * Return: zero if normal, non-zero if error.
 */
STATIC int
xlog_find_head(
	struct xlog	*log,
	xfs_daddr_t	*return_head_blk)
{
	xfs_buf_t	*bp;
	char		*offset;
	xfs_daddr_t	new_blk, first_blk, start_blk, last_blk, head_blk;
	int		num_scan_bblks;
	uint		first_half_cycle, last_half_cycle;
	uint		stop_on_cycle;
	int		error, log_bbnum = log->l_logBBsize;

	/* Is the end of the log device zeroed? */
	error = xlog_find_zeroed(log, &first_blk);
	if (error < 0) {
		xfs_warn(log->l_mp, "empty log check failed");
		return error;
	}
	if (error == 1) {
		*return_head_blk = first_blk;

		/* Is the whole lot zeroed? */
		if (!first_blk) {
			/* Linux XFS shouldn't generate totally zeroed logs -
			 * mkfs etc write a dummy unmount record to a fresh
			 * log so we can store the uuid in there
			 */
			xfs_warn(log->l_mp, "totally zeroed log");
		}

		return 0;
	}

	first_blk = 0;			/* get cycle # of 1st block */
	bp = xlog_get_bp(log, 1);
	if (!bp)
		return -ENOMEM;

	error = xlog_bread(log, 0, 1, bp, &offset);
	if (error)
		goto bp_err;

	first_half_cycle = xlog_get_cycle(offset);

	last_blk = head_blk = log_bbnum - 1;	/* get cycle # of last block */
	error = xlog_bread(log, last_blk, 1, bp, &offset);
	if (error)
		goto bp_err;

	last_half_cycle = xlog_get_cycle(offset);
	ASSERT(last_half_cycle != 0);

	/*
	 * If the 1st half cycle number is equal to the last half cycle number,
	 * then the entire log is stamped with the same cycle number.  In this
	 * case, head_blk can't be set to zero (which makes sense).  The below
	 * math doesn't work out properly with head_blk equal to zero.  Instead,
	 * we set it to log_bbnum which is an invalid block number, but this
	 * value makes the math correct.  If head_blk doesn't changed through
	 * all the tests below, *head_blk is set to zero at the very end rather
	 * than log_bbnum.  In a sense, log_bbnum and zero are the same block
	 * in a circular file.
	 */
	if (first_half_cycle == last_half_cycle) {
		/*
		 * In this case we believe that the entire log should have
		 * cycle number last_half_cycle.  We need to scan backwards
		 * from the end verifying that there are no holes still
		 * containing last_half_cycle - 1.  If we find such a hole,
		 * then the start of that hole will be the new head.  The
		 * simple case looks like
		 *        x | x ... | x - 1 | x
		 * Another case that fits this picture would be
		 *        x | x + 1 | x ... | x
		 * In this case the head really is somewhere at the end of the
		 * log, as one of the latest writes at the beginning was
		 * incomplete.
		 * One more case is
		 *        x | x + 1 | x ... | x - 1 | x
		 * This is really the combination of the above two cases, and
		 * the head has to end up at the start of the x-1 hole at the
		 * end of the log.
		 *
		 * In the 256k log case, we will read from the beginning to the
		 * end of the log and search for cycle numbers equal to x-1.
		 * We don't worry about the x+1 blocks that we encounter,
		 * because we know that they cannot be the head since the log
		 * started with x.
		 */
		head_blk = log_bbnum;
		stop_on_cycle = last_half_cycle - 1;
	} else {
		/*
		 * In this case we want to find the first block with cycle
		 * number matching last_half_cycle.  We expect the log to be
		 * some variation on
		 *        x + 1 ... | x ... | x
		 * The first block with cycle number x (last_half_cycle) will
		 * be where the new head belongs.  First we do a binary search
		 * for the first occurrence of last_half_cycle.  The binary
		 * search may not be totally accurate, so then we scan back
		 * from there looking for occurrences of last_half_cycle before
		 * us.  If that backwards scan wraps around the beginning of
		 * the log, then we look for occurrences of last_half_cycle - 1
		 * at the end of the log.  The cases we're looking for look
		 * like
		 *                               v binary search stopped here
		 *        x + 1 ... | x | x + 1 | x ... | x
		 *                   ^ but we want to locate this spot
		 * or
		 *        <---------> less than scan distance
		 *        x + 1 ... | x ... | x - 1 | x
		 *                           ^ we want to locate this spot
		 */
		stop_on_cycle = last_half_cycle;
		if ((error = xlog_find_cycle_start(log, bp, first_blk,
						&head_blk, last_half_cycle)))
			goto bp_err;
	}

	/*
	 * Now validate the answer.  Scan back some number of maximum possible
	 * blocks and make sure each one has the expected cycle number.  The
	 * maximum is determined by the total possible amount of buffering
	 * in the in-core log.  The following number can be made tighter if
	 * we actually look at the block size of the filesystem.
	 */
	num_scan_bblks = min_t(int, log_bbnum, XLOG_TOTAL_REC_SHIFT(log));
	if (head_blk >= num_scan_bblks) {
		/*
		 * We are guaranteed that the entire check can be performed
		 * in one buffer.
		 */
		start_blk = head_blk - num_scan_bblks;
		if ((error = xlog_find_verify_cycle(log,
						start_blk, num_scan_bblks,
						stop_on_cycle, &new_blk)))
			goto bp_err;
		if (new_blk != -1)
			head_blk = new_blk;
	} else {		/* need to read 2 parts of log */
		/*
		 * We are going to scan backwards in the log in two parts.
		 * First we scan the physical end of the log.  In this part
		 * of the log, we are looking for blocks with cycle number
		 * last_half_cycle - 1.
		 * If we find one, then we know that the log starts there, as
		 * we've found a hole that didn't get written in going around
		 * the end of the physical log.  The simple case for this is
		 *        x + 1 ... | x ... | x - 1 | x
		 *        <---------> less than scan distance
		 * If all of the blocks at the end of the log have cycle number
		 * last_half_cycle, then we check the blocks at the start of
		 * the log looking for occurrences of last_half_cycle.  If we
		 * find one, then our current estimate for the location of the
		 * first occurrence of last_half_cycle is wrong and we move
		 * back to the hole we've found.  This case looks like
		 *        x + 1 ... | x | x + 1 | x ...
		 *                               ^ binary search stopped here
		 * Another case we need to handle that only occurs in 256k
		 * logs is
		 *        x + 1 ... | x ... | x+1 | x ...
		 *                   ^ binary search stops here
		 * In a 256k log, the scan at the end of the log will see the
		 * x + 1 blocks.  We need to skip past those since that is
		 * certainly not the head of the log.  By searching for
		 * last_half_cycle-1 we accomplish that.
		 */
		ASSERT(head_blk <= INT_MAX &&
			(xfs_daddr_t) num_scan_bblks >= head_blk);
		start_blk = log_bbnum - (num_scan_bblks - head_blk);
		if ((error = xlog_find_verify_cycle(log, start_blk,
					num_scan_bblks - (int)head_blk,
					(stop_on_cycle - 1), &new_blk)))
			goto bp_err;
		if (new_blk != -1) {
			head_blk = new_blk;
			goto validate_head;
		}

		/*
		 * Scan beginning of log now.  The last part of the physical
		 * log is good.  This scan needs to verify that it doesn't find
		 * the last_half_cycle.
		 */
		start_blk = 0;
		ASSERT(head_blk <= INT_MAX);
		if ((error = xlog_find_verify_cycle(log,
					start_blk, (int)head_blk,
					stop_on_cycle, &new_blk)))
			goto bp_err;
		if (new_blk != -1)
			head_blk = new_blk;
	}

validate_head:
	/*
	 * Now we need to make sure head_blk is not pointing to a block in
	 * the middle of a log record.
	 */
	num_scan_bblks = XLOG_REC_SHIFT(log);
	if (head_blk >= num_scan_bblks) {
		start_blk = head_blk - num_scan_bblks; /* don't read head_blk */

		/* start ptr at last block ptr before head_blk */
		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
		if (error == 1)
			error = -EIO;
		if (error)
			goto bp_err;
	} else {
		start_blk = 0;
		ASSERT(head_blk <= INT_MAX);
		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
		if (error < 0)
			goto bp_err;
		if (error == 1) {
			/* We hit the beginning of the log during our search */
			start_blk = log_bbnum - (num_scan_bblks - head_blk);
			new_blk = log_bbnum;
			ASSERT(start_blk <= INT_MAX &&
				(xfs_daddr_t) log_bbnum-start_blk >= 0);
			ASSERT(head_blk <= INT_MAX);
			error = xlog_find_verify_log_record(log, start_blk,
							&new_blk, (int)head_blk);
			if (error == 1)
				error = -EIO;
			if (error)
				goto bp_err;
			if (new_blk != log_bbnum)
				head_blk = new_blk;
		} else if (error)
			goto bp_err;
	}

	xlog_put_bp(bp);
	if (head_blk == log_bbnum)
		*return_head_blk = 0;
	else
		*return_head_blk = head_blk;
	/*
	 * When returning here, we have a good block number.  Bad block
	 * means that during a previous crash, we didn't have a clean break
	 * from cycle number N to cycle number N-1.  In this case, we need
	 * to find the first block with cycle number N-1.
	 */
	return 0;

 bp_err:
	xlog_put_bp(bp);

	if (error)
		xfs_warn(log->l_mp, "failed to find log head");
	return error;
}

/*
 * Seek backwards in the log for log record headers.
 *
 * Given a starting log block, walk backwards until we find the provided number
 * of records or hit the provided tail block. The return value is the number of
 * records encountered or a negative error code. The log block and buffer
 * pointer of the last record seen are returned in rblk and rhead respectively.
 */
STATIC int
xlog_rseek_logrec_hdr(
	struct xlog		*log,
	xfs_daddr_t		head_blk,
	xfs_daddr_t		tail_blk,
	int			count,
	struct xfs_buf		*bp,
	xfs_daddr_t		*rblk,
	struct xlog_rec_header	**rhead,
	bool			*wrapped)
{
	int			i;
	int			error;
	int			found = 0;
	char			*offset = NULL;
	xfs_daddr_t		end_blk;

	*wrapped = false;

	/*
	 * Walk backwards from the head block until we hit the tail or the first
	 * block in the log.
	 */
	end_blk = head_blk > tail_blk ? tail_blk : 0;
	for (i = (int) head_blk - 1; i >= end_blk; i--) {
		error = xlog_bread(log, i, 1, bp, &offset);
		if (error)
			goto out_error;

		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
			*rblk = i;
			*rhead = (struct xlog_rec_header *) offset;
			if (++found == count)
				break;
		}
	}

	/*
	 * If we haven't hit the tail block or the log record header count,
	 * start looking again from the end of the physical log. Note that
	 * callers can pass head == tail if the tail is not yet known.
	 */
	if (tail_blk >= head_blk && found != count) {
		for (i = log->l_logBBsize - 1; i >= (int) tail_blk; i--) {
			error = xlog_bread(log, i, 1, bp, &offset);
			if (error)
				goto out_error;

			if (*(__be32 *)offset ==
			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
				*wrapped = true;
				*rblk = i;
				*rhead = (struct xlog_rec_header *) offset;
				if (++found == count)
					break;
			}
		}
	}

	return found;

out_error:
	return error;
}

/*
 * Seek forward in the log for log record headers.
 *
 * Given head and tail blocks, walk forward from the tail block until we find
 * the provided number of records or hit the head block. The return value is the
 * number of records encountered or a negative error code. The log block and
 * buffer pointer of the last record seen are returned in rblk and rhead
 * respectively.
 */
STATIC int
xlog_seek_logrec_hdr(
	struct xlog		*log,
	xfs_daddr_t		head_blk,
	xfs_daddr_t		tail_blk,
	int			count,
	struct xfs_buf		*bp,
	xfs_daddr_t		*rblk,
	struct xlog_rec_header	**rhead,
	bool			*wrapped)
{
	int			i;
	int			error;
	int			found = 0;
	char			*offset = NULL;
	xfs_daddr_t		end_blk;

	*wrapped = false;

	/*
	 * Walk forward from the tail block until we hit the head or the last
	 * block in the log.
	 */
	end_blk = head_blk > tail_blk ? head_blk : log->l_logBBsize - 1;
	for (i = (int) tail_blk; i <= end_blk; i++) {
		error = xlog_bread(log, i, 1, bp, &offset);
		if (error)
			goto out_error;

		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
			*rblk = i;
			*rhead = (struct xlog_rec_header *) offset;
			if (++found == count)
				break;
		}
	}

	/*
	 * If we haven't hit the head block or the log record header count,
	 * start looking again from the start of the physical log.
	 */
	if (tail_blk > head_blk && found != count) {
		for (i = 0; i < (int) head_blk; i++) {
			error = xlog_bread(log, i, 1, bp, &offset);
			if (error)
				goto out_error;

			if (*(__be32 *)offset ==
			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
				*wrapped = true;
				*rblk = i;
				*rhead = (struct xlog_rec_header *) offset;
				if (++found == count)
					break;
			}
		}
	}

	return found;

out_error:
	return error;
}

/*
 * Calculate distance from head to tail (i.e., unused space in the log).
 */
static inline int
xlog_tail_distance(
	struct xlog	*log,
	xfs_daddr_t	head_blk,
	xfs_daddr_t	tail_blk)
{
	if (head_blk < tail_blk)
		return tail_blk - head_blk;

	return tail_blk + (log->l_logBBsize - head_blk);
}

/*
 * Verify the log tail. This is particularly important when torn or incomplete
 * writes have been detected near the front of the log and the head has been
 * walked back accordingly.
 *
 * We also have to handle the case where the tail was pinned and the head
 * blocked behind the tail right before a crash. If the tail had been pushed
 * immediately prior to the crash and the subsequent checkpoint was only
 * partially written, it's possible it overwrote the last referenced tail in the
 * log with garbage. This is not a coherency problem because the tail must have
 * been pushed before it can be overwritten, but appears as log corruption to
 * recovery because we have no way to know the tail was updated if the
 * subsequent checkpoint didn't write successfully.
 *
 * Therefore, CRC check the log from tail to head. If a failure occurs and the
 * offending record is within max iclog bufs from the head, walk the tail
 * forward and retry until a valid tail is found or corruption is detected out
 * of the range of a possible overwrite.
 */
STATIC int
xlog_verify_tail(
	struct xlog		*log,
	xfs_daddr_t		head_blk,
	xfs_daddr_t		*tail_blk,
	int			hsize)
{
	struct xlog_rec_header	*thead;
	struct xfs_buf		*bp;
	xfs_daddr_t		first_bad;
	int			error = 0;
	bool			wrapped;
	xfs_daddr_t		tmp_tail;
	xfs_daddr_t		orig_tail = *tail_blk;

	bp = xlog_get_bp(log, 1);
	if (!bp)
		return -ENOMEM;

	/*
	 * Make sure the tail points to a record (returns positive count on
	 * success).
	 */
	error = xlog_seek_logrec_hdr(log, head_blk, *tail_blk, 1, bp,
			&tmp_tail, &thead, &wrapped);
	if (error < 0)
		goto out;
	if (*tail_blk != tmp_tail)
		*tail_blk = tmp_tail;

	/*
	 * Run a CRC check from the tail to the head. We can't just check
	 * MAX_ICLOGS records past the tail because the tail may point to stale
	 * blocks cleared during the search for the head/tail. These blocks are
	 * overwritten with zero-length records and thus record count is not a
	 * reliable indicator of the iclog state before a crash.
	 */
	first_bad = 0;
	error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
				      XLOG_RECOVER_CRCPASS, &first_bad);
	while ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
		int	tail_distance;

		/*
		 * Is corruption within range of the head? If so, retry from
		 * the next record. Otherwise return an error.
		 */
		tail_distance = xlog_tail_distance(log, head_blk, first_bad);
		if (tail_distance > BTOBB(XLOG_MAX_ICLOGS * hsize))
			break;

		/* skip to the next record; returns positive count on success */
		error = xlog_seek_logrec_hdr(log, head_blk, first_bad, 2, bp,
				&tmp_tail, &thead, &wrapped);
		if (error < 0)
			goto out;

		*tail_blk = tmp_tail;
		first_bad = 0;
		error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
					      XLOG_RECOVER_CRCPASS, &first_bad);
	}

	if (!error && *tail_blk != orig_tail)
		xfs_warn(log->l_mp,
		"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
			 orig_tail, *tail_blk);
out:
	xlog_put_bp(bp);
	return error;
}

/*
 * Detect and trim torn writes from the head of the log.
 *
 * Storage without sector atomicity guarantees can result in torn writes in the
 * log in the event of a crash. Our only means to detect this scenario is via
 * CRC verification. While we can't always be certain that CRC verification
 * failure is due to a torn write vs. an unrelated corruption, we do know that
 * only a certain number (XLOG_MAX_ICLOGS) of log records can be written out at
 * one time. Therefore, CRC verify up to XLOG_MAX_ICLOGS records at the head of
 * the log and treat failures in this range as torn writes as a matter of
 * policy. In the event of CRC failure, the head is walked back to the last good
 * record in the log and the tail is updated from that record and verified.
 */
STATIC int
xlog_verify_head(
	struct xlog		*log,
	xfs_daddr_t		*head_blk,	/* in/out: unverified head */
	xfs_daddr_t		*tail_blk,	/* out: tail block */
	struct xfs_buf		*bp,
	xfs_daddr_t		*rhead_blk,	/* start blk of last record */
	struct xlog_rec_header	**rhead,	/* ptr to last record */
	bool			*wrapped)	/* last rec. wraps phys. log */
{
	struct xlog_rec_header	*tmp_rhead;
	struct xfs_buf		*tmp_bp;
	xfs_daddr_t		first_bad;
	xfs_daddr_t		tmp_rhead_blk;
	int			found;
	int			error;
	bool			tmp_wrapped;

	/*
	 * Check the head of the log for torn writes. Search backwards from the
	 * head until we hit the tail or the maximum number of log record I/Os
	 * that could have been in flight at one time. Use a temporary buffer so
	 * we don't trash the rhead/bp pointers from the caller.
	 */
	tmp_bp = xlog_get_bp(log, 1);
	if (!tmp_bp)
		return -ENOMEM;
	error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
				      XLOG_MAX_ICLOGS, tmp_bp, &tmp_rhead_blk,
				      &tmp_rhead, &tmp_wrapped);
	xlog_put_bp(tmp_bp);
	if (error < 0)
		return error;

	/*
	 * Now run a CRC verification pass over the records starting at the
	 * block found above to the current head. If a CRC failure occurs, the
	 * log block of the first bad record is saved in first_bad.
	 */
	error = xlog_do_recovery_pass(log, *head_blk, tmp_rhead_blk,
				      XLOG_RECOVER_CRCPASS, &first_bad);
	if ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
		/*
		 * We've hit a potential torn write. Reset the error and warn
		 * about it.
		 */
		error = 0;
		xfs_warn(log->l_mp,
"Torn write (CRC failure) detected at log block 0x%llx. Truncating head block from 0x%llx.",
			 first_bad, *head_blk);

		/*
		 * Get the header block and buffer pointer for the last good
		 * record before the bad record.
		 *
		 * Note that xlog_find_tail() clears the blocks at the new head
		 * (i.e., the records with invalid CRC) if the cycle number
		 * matches the the current cycle.
		 */
		found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1, bp,
					      rhead_blk, rhead, wrapped);
		if (found < 0)
			return found;
		if (found == 0)		/* XXX: right thing to do here? */
			return -EIO;

		/*
		 * Reset the head block to the starting block of the first bad
		 * log record and set the tail block based on the last good
		 * record.
		 *
		 * Bail out if the updated head/tail match as this indicates
		 * possible corruption outside of the acceptable
		 * (XLOG_MAX_ICLOGS) range. This is a job for xfs_repair...
		 */
		*head_blk = first_bad;
		*tail_blk = BLOCK_LSN(be64_to_cpu((*rhead)->h_tail_lsn));
		if (*head_blk == *tail_blk) {
			ASSERT(0);
			return 0;
		}
	}
	if (error)
		return error;

	return xlog_verify_tail(log, *head_blk, tail_blk,
				be32_to_cpu((*rhead)->h_size));
}

/*
 * Check whether the head of the log points to an unmount record. In other
 * words, determine whether the log is clean. If so, update the in-core state
 * appropriately.
 */
static int
xlog_check_unmount_rec(
	struct xlog		*log,
	xfs_daddr_t		*head_blk,
	xfs_daddr_t		*tail_blk,
	struct xlog_rec_header	*rhead,
	xfs_daddr_t		rhead_blk,
	struct xfs_buf		*bp,
	bool			*clean)
{
	struct xlog_op_header	*op_head;
	xfs_daddr_t		umount_data_blk;
	xfs_daddr_t		after_umount_blk;
	int			hblks;
	int			error;
	char			*offset;

	*clean = false;

	/*
	 * Look for unmount record. If we find it, then we know there was a
	 * clean unmount. Since 'i' could be the last block in the physical
	 * log, we convert to a log block before comparing to the head_blk.
	 *
	 * Save the current tail lsn to use to pass to xlog_clear_stale_blocks()
	 * below. We won't want to clear the unmount record if there is one, so
	 * we pass the lsn of the unmount record rather than the block after it.
	 */
	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
		int	h_size = be32_to_cpu(rhead->h_size);
		int	h_version = be32_to_cpu(rhead->h_version);

		if ((h_version & XLOG_VERSION_2) &&
		    (h_size > XLOG_HEADER_CYCLE_SIZE)) {
			hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
			if (h_size % XLOG_HEADER_CYCLE_SIZE)
				hblks++;
		} else {
			hblks = 1;
		}
	} else {
		hblks = 1;
	}
	after_umount_blk = rhead_blk + hblks + BTOBB(be32_to_cpu(rhead->h_len));
	after_umount_blk = do_mod(after_umount_blk, log->l_logBBsize);
	if (*head_blk == after_umount_blk &&
	    be32_to_cpu(rhead->h_num_logops) == 1) {
		umount_data_blk = rhead_blk + hblks;
		umount_data_blk = do_mod(umount_data_blk, log->l_logBBsize);
		error = xlog_bread(log, umount_data_blk, 1, bp, &offset);
		if (error)
			return error;

		op_head = (struct xlog_op_header *)offset;
		if (op_head->oh_flags & XLOG_UNMOUNT_TRANS) {
			/*
			 * Set tail and last sync so that newly written log
			 * records will point recovery to after the current
			 * unmount record.
			 */
			xlog_assign_atomic_lsn(&log->l_tail_lsn,
					log->l_curr_cycle, after_umount_blk);
			xlog_assign_atomic_lsn(&log->l_last_sync_lsn,
					log->l_curr_cycle, after_umount_blk);
			*tail_blk = after_umount_blk;

			*clean = true;
		}
	}

	return 0;
}

static void
xlog_set_state(
	struct xlog		*log,
	xfs_daddr_t		head_blk,
	struct xlog_rec_header	*rhead,
	xfs_daddr_t		rhead_blk,
	bool			bump_cycle)
{
	/*
	 * Reset log values according to the state of the log when we
	 * crashed.  In the case where head_blk == 0, we bump curr_cycle
	 * one because the next write starts a new cycle rather than
	 * continuing the cycle of the last good log record.  At this
	 * point we have guaranteed that all partial log records have been
	 * accounted for.  Therefore, we know that the last good log record
	 * written was complete and ended exactly on the end boundary
	 * of the physical log.
	 */
	log->l_prev_block = rhead_blk;
	log->l_curr_block = (int)head_blk;
	log->l_curr_cycle = be32_to_cpu(rhead->h_cycle);
	if (bump_cycle)
		log->l_curr_cycle++;
	atomic64_set(&log->l_tail_lsn, be64_to_cpu(rhead->h_tail_lsn));
	atomic64_set(&log->l_last_sync_lsn, be64_to_cpu(rhead->h_lsn));
	xlog_assign_grant_head(&log->l_reserve_head.grant, log->l_curr_cycle,
					BBTOB(log->l_curr_block));
	xlog_assign_grant_head(&log->l_write_head.grant, log->l_curr_cycle,
					BBTOB(log->l_curr_block));
}

/*
 * Find the sync block number or the tail of the log.
 *
 * This will be the block number of the last record to have its
 * associated buffers synced to disk.  Every log record header has
 * a sync lsn embedded in it.  LSNs hold block numbers, so it is easy
 * to get a sync block number.  The only concern is to figure out which
 * log record header to believe.
 *
 * The following algorithm uses the log record header with the largest
 * lsn.  The entire log record does not need to be valid.  We only care
 * that the header is valid.
 *
 * We could speed up search by using current head_blk buffer, but it is not
 * available.
 */
STATIC int
xlog_find_tail(
	struct xlog		*log,
	xfs_daddr_t		*head_blk,
	xfs_daddr_t		*tail_blk)
{
	xlog_rec_header_t	*rhead;
	char			*offset = NULL;
	xfs_buf_t		*bp;
	int			error;
	xfs_daddr_t		rhead_blk;
	xfs_lsn_t		tail_lsn;
	bool			wrapped = false;
	bool			clean = false;

	/*
	 * Find previous log record
	 */
	if ((error = xlog_find_head(log, head_blk)))
		return error;
	ASSERT(*head_blk < INT_MAX);

	bp = xlog_get_bp(log, 1);
	if (!bp)
		return -ENOMEM;
	if (*head_blk == 0) {				/* special case */
		error = xlog_bread(log, 0, 1, bp, &offset);
		if (error)
			goto done;

		if (xlog_get_cycle(offset) == 0) {
			*tail_blk = 0;
			/* leave all other log inited values alone */
			goto done;
		}
	}

	/*
	 * Search backwards through the log looking for the log record header
	 * block. This wraps all the way back around to the head so something is
	 * seriously wrong if we can't find it.
	 */
	error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, bp,
				      &rhead_blk, &rhead, &wrapped);
	if (error < 0)
		return error;
	if (!error) {
		xfs_warn(log->l_mp, "%s: couldn't find sync record", __func__);
		return -EIO;
	}
	*tail_blk = BLOCK_LSN(be64_to_cpu(rhead->h_tail_lsn));

	/*
	 * Set the log state based on the current head record.
	 */
	xlog_set_state(log, *head_blk, rhead, rhead_blk, wrapped);
	tail_lsn = atomic64_read(&log->l_tail_lsn);

	/*
	 * Look for an unmount record at the head of the log. This sets the log
	 * state to determine whether recovery is necessary.
	 */
	error = xlog_check_unmount_rec(log, head_blk, tail_blk, rhead,
				       rhead_blk, bp, &clean);
	if (error)
		goto done;

	/*
	 * Verify the log head if the log is not clean (e.g., we have anything
	 * but an unmount record at the head). This uses CRC verification to
	 * detect and trim torn writes. If discovered, CRC failures are
	 * considered torn writes and the log head is trimmed accordingly.
	 *
	 * Note that we can only run CRC verification when the log is dirty
	 * because there's no guarantee that the log data behind an unmount
	 * record is compatible with the current architecture.
	 */
	if (!clean) {
		xfs_daddr_t	orig_head = *head_blk;

		error = xlog_verify_head(log, head_blk, tail_blk, bp,
					 &rhead_blk, &rhead, &wrapped);
		if (error)
			goto done;

		/* update in-core state again if the head changed */
		if (*head_blk != orig_head) {
			xlog_set_state(log, *head_blk, rhead, rhead_blk,
				       wrapped);
			tail_lsn = atomic64_read(&log->l_tail_lsn);
			error = xlog_check_unmount_rec(log, head_blk, tail_blk,
						       rhead, rhead_blk, bp,
						       &clean);
			if (error)
				goto done;
		}
	}

	/*
	 * Note that the unmount was clean. If the unmount was not clean, we
	 * need to know this to rebuild the superblock counters from the perag
	 * headers if we have a filesystem using non-persistent counters.
	 */
	if (clean)
		log->l_mp->m_flags |= XFS_MOUNT_WAS_CLEAN;

	/*
	 * Make sure that there are no blocks in front of the head
	 * with the same cycle number as the head.  This can happen
	 * because we allow multiple outstanding log writes concurrently,
	 * and the later writes might make it out before earlier ones.
	 *
	 * We use the lsn from before modifying it so that we'll never
	 * overwrite the unmount record after a clean unmount.
	 *
	 * Do this only if we are going to recover the filesystem
	 *
	 * NOTE: This used to say "if (!readonly)"
	 * However on Linux, we can & do recover a read-only filesystem.
	 * We only skip recovery if NORECOVERY is specified on mount,
	 * in which case we would not be here.
	 *
	 * But... if the -device- itself is readonly, just skip this.
	 * We can't recover this device anyway, so it won't matter.
	 */
	if (!xfs_readonly_buftarg(log->l_mp->m_logdev_targp))
		error = xlog_clear_stale_blocks(log, tail_lsn);

done:
	xlog_put_bp(bp);

	if (error)
		xfs_warn(log->l_mp, "failed to locate log tail");
	return error;
}

/*
 * Is the log zeroed at all?
 *
 * The last binary search should be changed to perform an X block read
 * once X becomes small enough.  You can then search linearly through
 * the X blocks.  This will cut down on the number of reads we need to do.
 *
 * If the log is partially zeroed, this routine will pass back the blkno
 * of the first block with cycle number 0.  It won't have a complete LR
 * preceding it.
 *
 * Return:
 *	0  => the log is completely written to
 *	1 => use *blk_no as the first block of the log
 *	<0 => error has occurred
 */
STATIC int
xlog_find_zeroed(
	struct xlog	*log,
	xfs_daddr_t	*blk_no)
{
	xfs_buf_t	*bp;
	char		*offset;
	uint	        first_cycle, last_cycle;
	xfs_daddr_t	new_blk, last_blk, start_blk;
	xfs_daddr_t     num_scan_bblks;
	int	        error, log_bbnum = log->l_logBBsize;

	*blk_no = 0;

	/* check totally zeroed log */
	bp = xlog_get_bp(log, 1);
	if (!bp)
		return -ENOMEM;
	error = xlog_bread(log, 0, 1, bp, &offset);
	if (error)
		goto bp_err;

	first_cycle = xlog_get_cycle(offset);
	if (first_cycle == 0) {		/* completely zeroed log */
		*blk_no = 0;
		xlog_put_bp(bp);
		return 1;
	}

	/* check partially zeroed log */
	error = xlog_bread(log, log_bbnum-1, 1, bp, &offset);
	if (error)
		goto bp_err;

	last_cycle = xlog_get_cycle(offset);
	if (last_cycle != 0) {		/* log completely written to */
		xlog_put_bp(bp);
		return 0;
	} else if (first_cycle != 1) {
		/*
		 * If the cycle of the last block is zero, the cycle of
		 * the first block must be 1. If it's not, maybe we're
		 * not looking at a log... Bail out.
		 */
		xfs_warn(log->l_mp,
			"Log inconsistent or not a log (last==0, first!=1)");
		error = -EINVAL;
		goto bp_err;
	}

	/* we have a partially zeroed log */
	last_blk = log_bbnum-1;
	if ((error = xlog_find_cycle_start(log, bp, 0, &last_blk, 0)))
		goto bp_err;

	/*
	 * Validate the answer.  Because there is no way to guarantee that
	 * the entire log is made up of log records which are the same size,
	 * we scan over the defined maximum blocks.  At this point, the maximum
	 * is not chosen to mean anything special.   XXXmiken
	 */
	num_scan_bblks = XLOG_TOTAL_REC_SHIFT(log);
	ASSERT(num_scan_bblks <= INT_MAX);

	if (last_blk < num_scan_bblks)
		num_scan_bblks = last_blk;
	start_blk = last_blk - num_scan_bblks;

	/*
	 * We search for any instances of cycle number 0 that occur before
	 * our current estimate of the head.  What we're trying to detect is
	 *        1 ... | 0 | 1 | 0...
	 *                       ^ binary search ends here
	 */
	if ((error = xlog_find_verify_cycle(log, start_blk,
					 (int)num_scan_bblks, 0, &new_blk)))
		goto bp_err;
	if (new_blk != -1)
		last_blk = new_blk;

	/*
	 * Potentially backup over partial log record write.  We don't need
	 * to search the end of the log because we know it is zero.
	 */
	error = xlog_find_verify_log_record(log, start_blk, &last_blk, 0);
	if (error == 1)
		error = -EIO;
	if (error)
		goto bp_err;

	*blk_no = last_blk;
bp_err:
	xlog_put_bp(bp);
	if (error)
		return error;
	return 1;
}

/*
 * These are simple subroutines used by xlog_clear_stale_blocks() below
 * to initialize a buffer full of empty log record headers and write
 * them into the log.
 */
STATIC void
xlog_add_record(
	struct xlog		*log,
	char			*buf,
	int			cycle,
	int			block,
	int			tail_cycle,
	int			tail_block)
{
	xlog_rec_header_t	*recp = (xlog_rec_header_t *)buf;

	memset(buf, 0, BBSIZE);
	recp->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
	recp->h_cycle = cpu_to_be32(cycle);
	recp->h_version = cpu_to_be32(
			xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? 2 : 1);
	recp->h_lsn = cpu_to_be64(xlog_assign_lsn(cycle, block));
	recp->h_tail_lsn = cpu_to_be64(xlog_assign_lsn(tail_cycle, tail_block));
	recp->h_fmt = cpu_to_be32(XLOG_FMT);
	memcpy(&recp->h_fs_uuid, &log->l_mp->m_sb.sb_uuid, sizeof(uuid_t));
}

STATIC int
xlog_write_log_records(
	struct xlog	*log,
	int		cycle,
	int		start_block,
	int		blocks,
	int		tail_cycle,
	int		tail_block)
{
	char		*offset;
	xfs_buf_t	*bp;
	int		balign, ealign;
	int		sectbb = log->l_sectBBsize;
	int		end_block = start_block + blocks;
	int		bufblks;
	int		error = 0;
	int		i, j = 0;

	/*
	 * Greedily allocate a buffer big enough to handle the full
	 * range of basic blocks to be written.  If that fails, try
	 * a smaller size.  We need to be able to write at least a
	 * log sector, or we're out of luck.
	 */
	bufblks = 1 << ffs(blocks);
	while (bufblks > log->l_logBBsize)
		bufblks >>= 1;
	while (!(bp = xlog_get_bp(log, bufblks))) {
		bufblks >>= 1;
		if (bufblks < sectbb)
			return -ENOMEM;
	}

	/* We may need to do a read at the start to fill in part of
	 * the buffer in the starting sector not covered by the first
	 * write below.
	 */
	balign = round_down(start_block, sectbb);
	if (balign != start_block) {
		error = xlog_bread_noalign(log, start_block, 1, bp);
		if (error)
			goto out_put_bp;

		j = start_block - balign;
	}

	for (i = start_block; i < end_block; i += bufblks) {
		int		bcount, endcount;

		bcount = min(bufblks, end_block - start_block);
		endcount = bcount - j;

		/* We may need to do a read at the end to fill in part of
		 * the buffer in the final sector not covered by the write.
		 * If this is the same sector as the above read, skip it.
		 */
		ealign = round_down(end_block, sectbb);
		if (j == 0 && (start_block + endcount > ealign)) {
			offset = bp->b_addr + BBTOB(ealign - start_block);
			error = xlog_bread_offset(log, ealign, sectbb,
							bp, offset);
			if (error)
				break;

		}

		offset = xlog_align(log, start_block, endcount, bp);
		for (; j < endcount; j++) {
			xlog_add_record(log, offset, cycle, i+j,
					tail_cycle, tail_block);
			offset += BBSIZE;
		}
		error = xlog_bwrite(log, start_block, endcount, bp);
		if (error)
			break;
		start_block += endcount;
		j = 0;
	}

 out_put_bp:
	xlog_put_bp(bp);
	return error;
}

/*
 * This routine is called to blow away any incomplete log writes out
 * in front of the log head.  We do this so that we won't become confused
 * if we come up, write only a little bit more, and then crash again.
 * If we leave the partial log records out there, this situation could
 * cause us to think those partial writes are valid blocks since they
 * have the current cycle number.  We get rid of them by overwriting them
 * with empty log records with the old cycle number rather than the
 * current one.
 *
 * The tail lsn is passed in rather than taken from
 * the log so that we will not write over the unmount record after a
 * clean unmount in a 512 block log.  Doing so would leave the log without
 * any valid log records in it until a new one was written.  If we crashed
 * during that time we would not be able to recover.
 */
STATIC int
xlog_clear_stale_blocks(
	struct xlog	*log,
	xfs_lsn_t	tail_lsn)
{
	int		tail_cycle, head_cycle;
	int		tail_block, head_block;
	int		tail_distance, max_distance;
	int		distance;
	int		error;

	tail_cycle = CYCLE_LSN(tail_lsn);
	tail_block = BLOCK_LSN(tail_lsn);
	head_cycle = log->l_curr_cycle;
	head_block = log->l_curr_block;

	/*
	 * Figure out the distance between the new head of the log
	 * and the tail.  We want to write over any blocks beyond the
	 * head that we may have written just before the crash, but
	 * we don't want to overwrite the tail of the log.
	 */
	if (head_cycle == tail_cycle) {
		/*
		 * The tail is behind the head in the physical log,
		 * so the distance from the head to the tail is the
		 * distance from the head to the end of the log plus
		 * the distance from the beginning of the log to the
		 * tail.
		 */
		if (unlikely(head_block < tail_block || head_block >= log->l_logBBsize)) {
			XFS_ERROR_REPORT("xlog_clear_stale_blocks(1)",
					 XFS_ERRLEVEL_LOW, log->l_mp);
			return -EFSCORRUPTED;
		}
		tail_distance = tail_block + (log->l_logBBsize - head_block);
	} else {
		/*
		 * The head is behind the tail in the physical log,
		 * so the distance from the head to the tail is just
		 * the tail block minus the head block.
		 */
		if (unlikely(head_block >= tail_block || head_cycle != (tail_cycle + 1))){
			XFS_ERROR_REPORT("xlog_clear_stale_blocks(2)",
					 XFS_ERRLEVEL_LOW, log->l_mp);
			return -EFSCORRUPTED;
		}
		tail_distance = tail_block - head_block;
	}

	/*
	 * If the head is right up against the tail, we can't clear
	 * anything.
	 */
	if (tail_distance <= 0) {
		ASSERT(tail_distance == 0);
		return 0;
	}

	max_distance = XLOG_TOTAL_REC_SHIFT(log);
	/*
	 * Take the smaller of the maximum amount of outstanding I/O
	 * we could have and the distance to the tail to clear out.
	 * We take the smaller so that we don't overwrite the tail and
	 * we don't waste all day writing from the head to the tail
	 * for no reason.
	 */
	max_distance = MIN(max_distance, tail_distance);

	if ((head_block + max_distance) <= log->l_logBBsize) {
		/*
		 * We can stomp all the blocks we need to without
		 * wrapping around the end of the log.  Just do it
		 * in a single write.  Use the cycle number of the
		 * current cycle minus one so that the log will look like:
		 *     n ... | n - 1 ...
		 */
		error = xlog_write_log_records(log, (head_cycle - 1),
				head_block, max_distance, tail_cycle,
				tail_block);
		if (error)
			return error;
	} else {
		/*
		 * We need to wrap around the end of the physical log in
		 * order to clear all the blocks.  Do it in two separate
		 * I/Os.  The first write should be from the head to the
		 * end of the physical log, and it should use the current
		 * cycle number minus one just like above.
		 */
		distance = log->l_logBBsize - head_block;
		error = xlog_write_log_records(log, (head_cycle - 1),
				head_block, distance, tail_cycle,
				tail_block);

		if (error)
			return error;

		/*
		 * Now write the blocks at the start of the physical log.
		 * This writes the remainder of the blocks we want to clear.
		 * It uses the current cycle number since we're now on the
		 * same cycle as the head so that we get:
		 *    n ... n ... | n - 1 ...
		 *    ^^^^^ blocks we're writing
		 */
		distance = max_distance - (log->l_logBBsize - head_block);
		error = xlog_write_log_records(log, head_cycle, 0, distance,
				tail_cycle, tail_block);
		if (error)
			return error;
	}

	return 0;
}

/******************************************************************************
 *
 *		Log recover routines
 *
 ******************************************************************************
 */

/*
 * Sort the log items in the transaction.
 *
 * The ordering constraints are defined by the inode allocation and unlink
 * behaviour. The rules are:
 *
 *	1. Every item is only logged once in a given transaction. Hence it
 *	   represents the last logged state of the item. Hence ordering is
 *	   dependent on the order in which operations need to be performed so
 *	   required initial conditions are always met.
 *
 *	2. Cancelled buffers are recorded in pass 1 in a separate table and
 *	   there's nothing to replay from them so we can simply cull them
 *	   from the transaction. However, we can't do that until after we've
 *	   replayed all the other items because they may be dependent on the
 *	   cancelled buffer and replaying the cancelled buffer can remove it
 *	   form the cancelled buffer table. Hence they have tobe done last.
 *
 *	3. Inode allocation buffers must be replayed before inode items that
 *	   read the buffer and replay changes into it. For filesystems using the
 *	   ICREATE transactions, this means XFS_LI_ICREATE objects need to get
 *	   treated the same as inode allocation buffers as they create and
 *	   initialise the buffers directly.
 *
 *	4. Inode unlink buffers must be replayed after inode items are replayed.
 *	   This ensures that inodes are completely flushed to the inode buffer
 *	   in a "free" state before we remove the unlinked inode list pointer.
 *
 * Hence the ordering needs to be inode allocation buffers first, inode items
 * second, inode unlink buffers third and cancelled buffers last.
 *
 * But there's a problem with that - we can't tell an inode allocation buffer
 * apart from a regular buffer, so we can't separate them. We can, however,
 * tell an inode unlink buffer from the others, and so we can separate them out
 * from all the other buffers and move them to last.
 *
 * Hence, 4 lists, in order from head to tail:
 *	- buffer_list for all buffers except cancelled/inode unlink buffers
 *	- item_list for all non-buffer items
 *	- inode_buffer_list for inode unlink buffers
 *	- cancel_list for the cancelled buffers
 *
 * Note that we add objects to the tail of the lists so that first-to-last
 * ordering is preserved within the lists. Adding objects to the head of the
 * list means when we traverse from the head we walk them in last-to-first
 * order. For cancelled buffers and inode unlink buffers this doesn't matter,
 * but for all other items there may be specific ordering that we need to
 * preserve.
 */
STATIC int
xlog_recover_reorder_trans(
	struct xlog		*log,
	struct xlog_recover	*trans,
	int			pass)
{
	xlog_recover_item_t	*item, *n;
	int			error = 0;
	LIST_HEAD(sort_list);
	LIST_HEAD(cancel_list);
	LIST_HEAD(buffer_list);
	LIST_HEAD(inode_buffer_list);
	LIST_HEAD(inode_list);

	list_splice_init(&trans->r_itemq, &sort_list);
	list_for_each_entry_safe(item, n, &sort_list, ri_list) {
		xfs_buf_log_format_t	*buf_f = item->ri_buf[0].i_addr;

		switch (ITEM_TYPE(item)) {
		case XFS_LI_ICREATE:
			list_move_tail(&item->ri_list, &buffer_list);
			break;
		case XFS_LI_BUF:
			if (buf_f->blf_flags & XFS_BLF_CANCEL) {
				trace_xfs_log_recover_item_reorder_head(log,
							trans, item, pass);
				list_move(&item->ri_list, &cancel_list);
				break;
			}
			if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
				list_move(&item->ri_list, &inode_buffer_list);
				break;
			}
			list_move_tail(&item->ri_list, &buffer_list);
			break;
		case XFS_LI_INODE:
		case XFS_LI_DQUOT:
		case XFS_LI_QUOTAOFF:
		case XFS_LI_EFD:
		case XFS_LI_EFI:
		case XFS_LI_RUI:
		case XFS_LI_RUD:
		case XFS_LI_CUI:
		case XFS_LI_CUD:
		case XFS_LI_BUI:
		case XFS_LI_BUD:
			trace_xfs_log_recover_item_reorder_tail(log,
							trans, item, pass);
			list_move_tail(&item->ri_list, &inode_list);
			break;
		default:
			xfs_warn(log->l_mp,
				"%s: unrecognized type of log operation",
				__func__);
			ASSERT(0);
			/*
			 * return the remaining items back to the transaction
			 * item list so they can be freed in caller.
			 */
			if (!list_empty(&sort_list))
				list_splice_init(&sort_list, &trans->r_itemq);
			error = -EIO;
			goto out;
		}
	}
out:
	ASSERT(list_empty(&sort_list));
	if (!list_empty(&buffer_list))
		list_splice(&buffer_list, &trans->r_itemq);
	if (!list_empty(&inode_list))
		list_splice_tail(&inode_list, &trans->r_itemq);
	if (!list_empty(&inode_buffer_list))
		list_splice_tail(&inode_buffer_list, &trans->r_itemq);
	if (!list_empty(&cancel_list))
		list_splice_tail(&cancel_list, &trans->r_itemq);
	return error;
}

/*
 * Build up the table of buf cancel records so that we don't replay
 * cancelled data in the second pass.  For buffer records that are
 * not cancel records, there is nothing to do here so we just return.
 *
 * If we get a cancel record which is already in the table, this indicates
 * that the buffer was cancelled multiple times.  In order to ensure
 * that during pass 2 we keep the record in the table until we reach its
 * last occurrence in the log, we keep a reference count in the cancel
 * record in the table to tell us how many times we expect to see this
 * record during the second pass.
 */
STATIC int
xlog_recover_buffer_pass1(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	xfs_buf_log_format_t	*buf_f = item->ri_buf[0].i_addr;
	struct list_head	*bucket;
	struct xfs_buf_cancel	*bcp;

	/*
	 * If this isn't a cancel buffer item, then just return.
	 */
	if (!(buf_f->blf_flags & XFS_BLF_CANCEL)) {
		trace_xfs_log_recover_buf_not_cancel(log, buf_f);
		return 0;
	}

	/*
	 * Insert an xfs_buf_cancel record into the hash table of them.
	 * If there is already an identical record, bump its reference count.
	 */
	bucket = XLOG_BUF_CANCEL_BUCKET(log, buf_f->blf_blkno);
	list_for_each_entry(bcp, bucket, bc_list) {
		if (bcp->bc_blkno == buf_f->blf_blkno &&
		    bcp->bc_len == buf_f->blf_len) {
			bcp->bc_refcount++;
			trace_xfs_log_recover_buf_cancel_ref_inc(log, buf_f);
			return 0;
		}
	}

	bcp = kmem_alloc(sizeof(struct xfs_buf_cancel), KM_SLEEP);
	bcp->bc_blkno = buf_f->blf_blkno;
	bcp->bc_len = buf_f->blf_len;
	bcp->bc_refcount = 1;
	list_add_tail(&bcp->bc_list, bucket);

	trace_xfs_log_recover_buf_cancel_add(log, buf_f);
	return 0;
}

/*
 * Check to see whether the buffer being recovered has a corresponding
 * entry in the buffer cancel record table. If it is, return the cancel
 * buffer structure to the caller.
 */
STATIC struct xfs_buf_cancel *
xlog_peek_buffer_cancelled(
	struct xlog		*log,
	xfs_daddr_t		blkno,
	uint			len,
	unsigned short			flags)
{
	struct list_head	*bucket;
	struct xfs_buf_cancel	*bcp;

	if (!log->l_buf_cancel_table) {
		/* empty table means no cancelled buffers in the log */
		ASSERT(!(flags & XFS_BLF_CANCEL));
		return NULL;
	}

	bucket = XLOG_BUF_CANCEL_BUCKET(log, blkno);
	list_for_each_entry(bcp, bucket, bc_list) {
		if (bcp->bc_blkno == blkno && bcp->bc_len == len)
			return bcp;
	}

	/*
	 * We didn't find a corresponding entry in the table, so return 0 so
	 * that the buffer is NOT cancelled.
	 */
	ASSERT(!(flags & XFS_BLF_CANCEL));
	return NULL;
}

/*
 * If the buffer is being cancelled then return 1 so that it will be cancelled,
 * otherwise return 0.  If the buffer is actually a buffer cancel item
 * (XFS_BLF_CANCEL is set), then decrement the refcount on the entry in the
 * table and remove it from the table if this is the last reference.
 *
 * We remove the cancel record from the table when we encounter its last
 * occurrence in the log so that if the same buffer is re-used again after its
 * last cancellation we actually replay the changes made at that point.
 */
STATIC int
xlog_check_buffer_cancelled(
	struct xlog		*log,
	xfs_daddr_t		blkno,
	uint			len,
	unsigned short			flags)
{
	struct xfs_buf_cancel	*bcp;

	bcp = xlog_peek_buffer_cancelled(log, blkno, len, flags);
	if (!bcp)
		return 0;

	/*
	 * We've go a match, so return 1 so that the recovery of this buffer
	 * is cancelled.  If this buffer is actually a buffer cancel log
	 * item, then decrement the refcount on the one in the table and
	 * remove it if this is the last reference.
	 */
	if (flags & XFS_BLF_CANCEL) {
		if (--bcp->bc_refcount == 0) {
			list_del(&bcp->bc_list);
			kmem_free(bcp);
		}
	}
	return 1;
}

/*
 * Perform recovery for a buffer full of inodes.  In these buffers, the only
 * data which should be recovered is that which corresponds to the
 * di_next_unlinked pointers in the on disk inode structures.  The rest of the
 * data for the inodes is always logged through the inodes themselves rather
 * than the inode buffer and is recovered in xlog_recover_inode_pass2().
 *
 * The only time when buffers full of inodes are fully recovered is when the
 * buffer is full of newly allocated inodes.  In this case the buffer will
 * not be marked as an inode buffer and so will be sent to
 * xlog_recover_do_reg_buffer() below during recovery.
 */
STATIC int
xlog_recover_do_inode_buffer(
	struct xfs_mount	*mp,
	xlog_recover_item_t	*item,
	struct xfs_buf		*bp,
	xfs_buf_log_format_t	*buf_f)
{
	int			i;
	int			item_index = 0;
	int			bit = 0;
	int			nbits = 0;
	int			reg_buf_offset = 0;
	int			reg_buf_bytes = 0;
	int			next_unlinked_offset;
	int			inodes_per_buf;
	xfs_agino_t		*logged_nextp;
	xfs_agino_t		*buffer_nextp;

	trace_xfs_log_recover_buf_inode_buf(mp->m_log, buf_f);

	/*
	 * Post recovery validation only works properly on CRC enabled
	 * filesystems.
	 */
	if (xfs_sb_version_hascrc(&mp->m_sb))
		bp->b_ops = &xfs_inode_buf_ops;

	inodes_per_buf = BBTOB(bp->b_io_length) >> mp->m_sb.sb_inodelog;
	for (i = 0; i < inodes_per_buf; i++) {
		next_unlinked_offset = (i * mp->m_sb.sb_inodesize) +
			offsetof(xfs_dinode_t, di_next_unlinked);

		while (next_unlinked_offset >=
		       (reg_buf_offset + reg_buf_bytes)) {
			/*
			 * The next di_next_unlinked field is beyond
			 * the current logged region.  Find the next
			 * logged region that contains or is beyond
			 * the current di_next_unlinked field.
			 */
			bit += nbits;
			bit = xfs_next_bit(buf_f->blf_data_map,
					   buf_f->blf_map_size, bit);

			/*
			 * If there are no more logged regions in the
			 * buffer, then we're done.
			 */
			if (bit == -1)
				return 0;

			nbits = xfs_contig_bits(buf_f->blf_data_map,
						buf_f->blf_map_size, bit);
			ASSERT(nbits > 0);
			reg_buf_offset = bit << XFS_BLF_SHIFT;
			reg_buf_bytes = nbits << XFS_BLF_SHIFT;
			item_index++;
		}

		/*
		 * If the current logged region starts after the current
		 * di_next_unlinked field, then move on to the next
		 * di_next_unlinked field.
		 */
		if (next_unlinked_offset < reg_buf_offset)
			continue;

		ASSERT(item->ri_buf[item_index].i_addr != NULL);
		ASSERT((item->ri_buf[item_index].i_len % XFS_BLF_CHUNK) == 0);
		ASSERT((reg_buf_offset + reg_buf_bytes) <=
							BBTOB(bp->b_io_length));

		/*
		 * The current logged region contains a copy of the
		 * current di_next_unlinked field.  Extract its value
		 * and copy it to the buffer copy.
		 */
		logged_nextp = item->ri_buf[item_index].i_addr +
				next_unlinked_offset - reg_buf_offset;
		if (unlikely(*logged_nextp == 0)) {
			xfs_alert(mp,
		"Bad inode buffer log record (ptr = "PTR_FMT", bp = "PTR_FMT"). "
		"Trying to replay bad (0) inode di_next_unlinked field.",
				item, bp);
			XFS_ERROR_REPORT("xlog_recover_do_inode_buf",
					 XFS_ERRLEVEL_LOW, mp);
			return -EFSCORRUPTED;
		}

		buffer_nextp = xfs_buf_offset(bp, next_unlinked_offset);
		*buffer_nextp = *logged_nextp;

		/*
		 * If necessary, recalculate the CRC in the on-disk inode. We
		 * have to leave the inode in a consistent state for whoever
		 * reads it next....
		 */
		xfs_dinode_calc_crc(mp,
				xfs_buf_offset(bp, i * mp->m_sb.sb_inodesize));

	}

	return 0;
}

/*
 * V5 filesystems know the age of the buffer on disk being recovered. We can
 * have newer objects on disk than we are replaying, and so for these cases we
 * don't want to replay the current change as that will make the buffer contents
 * temporarily invalid on disk.
 *
 * The magic number might not match the buffer type we are going to recover
 * (e.g. reallocated blocks), so we ignore the xfs_buf_log_format flags.  Hence
 * extract the LSN of the existing object in the buffer based on it's current
 * magic number.  If we don't recognise the magic number in the buffer, then
 * return a LSN of -1 so that the caller knows it was an unrecognised block and
 * so can recover the buffer.
 *
 * Note: we cannot rely solely on magic number matches to determine that the
 * buffer has a valid LSN - we also need to verify that it belongs to this
 * filesystem, so we need to extract the object's LSN and compare it to that
 * which we read from the superblock. If the UUIDs don't match, then we've got a
 * stale metadata block from an old filesystem instance that we need to recover
 * over the top of.
 */
static xfs_lsn_t
xlog_recover_get_buf_lsn(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp)
{
	uint32_t		magic32;
	uint16_t		magic16;
	uint16_t		magicda;
	void			*blk = bp->b_addr;
	uuid_t			*uuid;
	xfs_lsn_t		lsn = -1;

	/* v4 filesystems always recover immediately */
	if (!xfs_sb_version_hascrc(&mp->m_sb))
		goto recover_immediately;

	magic32 = be32_to_cpu(*(__be32 *)blk);
	switch (magic32) {
	case XFS_ABTB_CRC_MAGIC:
	case XFS_ABTC_CRC_MAGIC:
	case XFS_ABTB_MAGIC:
	case XFS_ABTC_MAGIC:
	case XFS_RMAP_CRC_MAGIC:
	case XFS_REFC_CRC_MAGIC:
	case XFS_IBT_CRC_MAGIC:
	case XFS_IBT_MAGIC: {
		struct xfs_btree_block *btb = blk;

		lsn = be64_to_cpu(btb->bb_u.s.bb_lsn);
		uuid = &btb->bb_u.s.bb_uuid;
		break;
	}
	case XFS_BMAP_CRC_MAGIC:
	case XFS_BMAP_MAGIC: {
		struct xfs_btree_block *btb = blk;

		lsn = be64_to_cpu(btb->bb_u.l.bb_lsn);
		uuid = &btb->bb_u.l.bb_uuid;
		break;
	}
	case XFS_AGF_MAGIC:
		lsn = be64_to_cpu(((struct xfs_agf *)blk)->agf_lsn);
		uuid = &((struct xfs_agf *)blk)->agf_uuid;
		break;
	case XFS_AGFL_MAGIC:
		lsn = be64_to_cpu(((struct xfs_agfl *)blk)->agfl_lsn);
		uuid = &((struct xfs_agfl *)blk)->agfl_uuid;
		break;
	case XFS_AGI_MAGIC:
		lsn = be64_to_cpu(((struct xfs_agi *)blk)->agi_lsn);
		uuid = &((struct xfs_agi *)blk)->agi_uuid;
		break;
	case XFS_SYMLINK_MAGIC:
		lsn = be64_to_cpu(((struct xfs_dsymlink_hdr *)blk)->sl_lsn);
		uuid = &((struct xfs_dsymlink_hdr *)blk)->sl_uuid;
		break;
	case XFS_DIR3_BLOCK_MAGIC:
	case XFS_DIR3_DATA_MAGIC:
	case XFS_DIR3_FREE_MAGIC:
		lsn = be64_to_cpu(((struct xfs_dir3_blk_hdr *)blk)->lsn);
		uuid = &((struct xfs_dir3_blk_hdr *)blk)->uuid;
		break;
	case XFS_ATTR3_RMT_MAGIC:
		/*
		 * Remote attr blocks are written synchronously, rather than
		 * being logged. That means they do not contain a valid LSN
		 * (i.e. transactionally ordered) in them, and hence any time we
		 * see a buffer to replay over the top of a remote attribute
		 * block we should simply do so.
		 */
		goto recover_immediately;
	case XFS_SB_MAGIC:
		/*
		 * superblock uuids are magic. We may or may not have a
		 * sb_meta_uuid on disk, but it will be set in the in-core
		 * superblock. We set the uuid pointer for verification
		 * according to the superblock feature mask to ensure we check
		 * the relevant UUID in the superblock.
		 */
		lsn = be64_to_cpu(((struct xfs_dsb *)blk)->sb_lsn);
		if (xfs_sb_version_hasmetauuid(&mp->m_sb))
			uuid = &((struct xfs_dsb *)blk)->sb_meta_uuid;
		else
			uuid = &((struct xfs_dsb *)blk)->sb_uuid;
		break;
	default:
		break;
	}

	if (lsn != (xfs_lsn_t)-1) {
		if (!uuid_equal(&mp->m_sb.sb_meta_uuid, uuid))
			goto recover_immediately;
		return lsn;
	}

	magicda = be16_to_cpu(((struct xfs_da_blkinfo *)blk)->magic);
	switch (magicda) {
	case XFS_DIR3_LEAF1_MAGIC:
	case XFS_DIR3_LEAFN_MAGIC:
	case XFS_DA3_NODE_MAGIC:
		lsn = be64_to_cpu(((struct xfs_da3_blkinfo *)blk)->lsn);
		uuid = &((struct xfs_da3_blkinfo *)blk)->uuid;
		break;
	default:
		break;
	}

	if (lsn != (xfs_lsn_t)-1) {
		if (!uuid_equal(&mp->m_sb.sb_uuid, uuid))
			goto recover_immediately;
		return lsn;
	}

	/*
	 * We do individual object checks on dquot and inode buffers as they
	 * have their own individual LSN records. Also, we could have a stale
	 * buffer here, so we have to at least recognise these buffer types.
	 *
	 * A notd complexity here is inode unlinked list processing - it logs
	 * the inode directly in the buffer, but we don't know which inodes have
	 * been modified, and there is no global buffer LSN. Hence we need to
	 * recover all inode buffer types immediately. This problem will be
	 * fixed by logical logging of the unlinked list modifications.
	 */
	magic16 = be16_to_cpu(*(__be16 *)blk);
	switch (magic16) {
	case XFS_DQUOT_MAGIC:
	case XFS_DINODE_MAGIC:
		goto recover_immediately;
	default:
		break;
	}

	/* unknown buffer contents, recover immediately */

recover_immediately:
	return (xfs_lsn_t)-1;

}

/*
 * Validate the recovered buffer is of the correct type and attach the
 * appropriate buffer operations to them for writeback. Magic numbers are in a
 * few places:
 *	the first 16 bits of the buffer (inode buffer, dquot buffer),
 *	the first 32 bits of the buffer (most blocks),
 *	inside a struct xfs_da_blkinfo at the start of the buffer.
 */
static void
xlog_recover_validate_buf_type(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	xfs_buf_log_format_t	*buf_f,
	xfs_lsn_t		current_lsn)
{
	struct xfs_da_blkinfo	*info = bp->b_addr;
	uint32_t		magic32;
	uint16_t		magic16;
	uint16_t		magicda;
	char			*warnmsg = NULL;

	/*
	 * We can only do post recovery validation on items on CRC enabled
	 * fielsystems as we need to know when the buffer was written to be able
	 * to determine if we should have replayed the item. If we replay old
	 * metadata over a newer buffer, then it will enter a temporarily
	 * inconsistent state resulting in verification failures. Hence for now
	 * just avoid the verification stage for non-crc filesystems
	 */
	if (!xfs_sb_version_hascrc(&mp->m_sb))
		return;

	magic32 = be32_to_cpu(*(__be32 *)bp->b_addr);
	magic16 = be16_to_cpu(*(__be16*)bp->b_addr);
	magicda = be16_to_cpu(info->magic);
	switch (xfs_blft_from_flags(buf_f)) {
	case XFS_BLFT_BTREE_BUF:
		switch (magic32) {
		case XFS_ABTB_CRC_MAGIC:
		case XFS_ABTC_CRC_MAGIC:
		case XFS_ABTB_MAGIC:
		case XFS_ABTC_MAGIC:
			bp->b_ops = &xfs_allocbt_buf_ops;
			break;
		case XFS_IBT_CRC_MAGIC:
		case XFS_FIBT_CRC_MAGIC:
		case XFS_IBT_MAGIC:
		case XFS_FIBT_MAGIC:
			bp->b_ops = &xfs_inobt_buf_ops;
			break;
		case XFS_BMAP_CRC_MAGIC:
		case XFS_BMAP_MAGIC:
			bp->b_ops = &xfs_bmbt_buf_ops;
			break;
		case XFS_RMAP_CRC_MAGIC:
			bp->b_ops = &xfs_rmapbt_buf_ops;
			break;
		case XFS_REFC_CRC_MAGIC:
			bp->b_ops = &xfs_refcountbt_buf_ops;
			break;
		default:
			warnmsg = "Bad btree block magic!";
			break;
		}
		break;
	case XFS_BLFT_AGF_BUF:
		if (magic32 != XFS_AGF_MAGIC) {
			warnmsg = "Bad AGF block magic!";
			break;
		}
		bp->b_ops = &xfs_agf_buf_ops;
		break;
	case XFS_BLFT_AGFL_BUF:
		if (magic32 != XFS_AGFL_MAGIC) {
			warnmsg = "Bad AGFL block magic!";
			break;
		}
		bp->b_ops = &xfs_agfl_buf_ops;
		break;
	case XFS_BLFT_AGI_BUF:
		if (magic32 != XFS_AGI_MAGIC) {
			warnmsg = "Bad AGI block magic!";
			break;
		}
		bp->b_ops = &xfs_agi_buf_ops;
		break;
	case XFS_BLFT_UDQUOT_BUF:
	case XFS_BLFT_PDQUOT_BUF:
	case XFS_BLFT_GDQUOT_BUF:
#ifdef CONFIG_XFS_QUOTA
		if (magic16 != XFS_DQUOT_MAGIC) {
			warnmsg = "Bad DQUOT block magic!";
			break;
		}
		bp->b_ops = &xfs_dquot_buf_ops;
#else
		xfs_alert(mp,
	"Trying to recover dquots without QUOTA support built in!");
		ASSERT(0);
#endif
		break;
	case XFS_BLFT_DINO_BUF:
		if (magic16 != XFS_DINODE_MAGIC) {
			warnmsg = "Bad INODE block magic!";
			break;
		}
		bp->b_ops = &xfs_inode_buf_ops;
		break;
	case XFS_BLFT_SYMLINK_BUF:
		if (magic32 != XFS_SYMLINK_MAGIC) {
			warnmsg = "Bad symlink block magic!";
			break;
		}
		bp->b_ops = &xfs_symlink_buf_ops;
		break;
	case XFS_BLFT_DIR_BLOCK_BUF:
		if (magic32 != XFS_DIR2_BLOCK_MAGIC &&
		    magic32 != XFS_DIR3_BLOCK_MAGIC) {
			warnmsg = "Bad dir block magic!";
			break;
		}
		bp->b_ops = &xfs_dir3_block_buf_ops;
		break;
	case XFS_BLFT_DIR_DATA_BUF:
		if (magic32 != XFS_DIR2_DATA_MAGIC &&
		    magic32 != XFS_DIR3_DATA_MAGIC) {
			warnmsg = "Bad dir data magic!";
			break;
		}
		bp->b_ops = &xfs_dir3_data_buf_ops;
		break;
	case XFS_BLFT_DIR_FREE_BUF:
		if (magic32 != XFS_DIR2_FREE_MAGIC &&
		    magic32 != XFS_DIR3_FREE_MAGIC) {
			warnmsg = "Bad dir3 free magic!";
			break;
		}
		bp->b_ops = &xfs_dir3_free_buf_ops;
		break;
	case XFS_BLFT_DIR_LEAF1_BUF:
		if (magicda != XFS_DIR2_LEAF1_MAGIC &&
		    magicda != XFS_DIR3_LEAF1_MAGIC) {
			warnmsg = "Bad dir leaf1 magic!";
			break;
		}
		bp->b_ops = &xfs_dir3_leaf1_buf_ops;
		break;
	case XFS_BLFT_DIR_LEAFN_BUF:
		if (magicda != XFS_DIR2_LEAFN_MAGIC &&
		    magicda != XFS_DIR3_LEAFN_MAGIC) {
			warnmsg = "Bad dir leafn magic!";
			break;
		}
		bp->b_ops = &xfs_dir3_leafn_buf_ops;
		break;
	case XFS_BLFT_DA_NODE_BUF:
		if (magicda != XFS_DA_NODE_MAGIC &&
		    magicda != XFS_DA3_NODE_MAGIC) {
			warnmsg = "Bad da node magic!";
			break;
		}
		bp->b_ops = &xfs_da3_node_buf_ops;
		break;
	case XFS_BLFT_ATTR_LEAF_BUF:
		if (magicda != XFS_ATTR_LEAF_MAGIC &&
		    magicda != XFS_ATTR3_LEAF_MAGIC) {
			warnmsg = "Bad attr leaf magic!";
			break;
		}
		bp->b_ops = &xfs_attr3_leaf_buf_ops;
		break;
	case XFS_BLFT_ATTR_RMT_BUF:
		if (magic32 != XFS_ATTR3_RMT_MAGIC) {
			warnmsg = "Bad attr remote magic!";
			break;
		}
		bp->b_ops = &xfs_attr3_rmt_buf_ops;
		break;
	case XFS_BLFT_SB_BUF:
		if (magic32 != XFS_SB_MAGIC) {
			warnmsg = "Bad SB block magic!";
			break;
		}
		bp->b_ops = &xfs_sb_buf_ops;
		break;
#ifdef CONFIG_XFS_RT
	case XFS_BLFT_RTBITMAP_BUF:
	case XFS_BLFT_RTSUMMARY_BUF:
		/* no magic numbers for verification of RT buffers */
		bp->b_ops = &xfs_rtbuf_ops;
		break;
#endif /* CONFIG_XFS_RT */
	default:
		xfs_warn(mp, "Unknown buffer type %d!",
			 xfs_blft_from_flags(buf_f));
		break;
	}

	/*
	 * Nothing else to do in the case of a NULL current LSN as this means
	 * the buffer is more recent than the change in the log and will be
	 * skipped.
	 */
	if (current_lsn == NULLCOMMITLSN)
		return;

	if (warnmsg) {
		xfs_warn(mp, warnmsg);
		ASSERT(0);
	}

	/*
	 * We must update the metadata LSN of the buffer as it is written out to
	 * ensure that older transactions never replay over this one and corrupt
	 * the buffer. This can occur if log recovery is interrupted at some
	 * point after the current transaction completes, at which point a
	 * subsequent mount starts recovery from the beginning.
	 *
	 * Write verifiers update the metadata LSN from log items attached to
	 * the buffer. Therefore, initialize a bli purely to carry the LSN to
	 * the verifier. We'll clean it up in our ->iodone() callback.
	 */
	if (bp->b_ops) {
		struct xfs_buf_log_item	*bip;

		ASSERT(!bp->b_iodone || bp->b_iodone == xlog_recover_iodone);
		bp->b_iodone = xlog_recover_iodone;
		xfs_buf_item_init(bp, mp);
		bip = bp->b_log_item;
		bip->bli_item.li_lsn = current_lsn;
	}
}

/*
 * Perform a 'normal' buffer recovery.  Each logged region of the
 * buffer should be copied over the corresponding region in the
 * given buffer.  The bitmap in the buf log format structure indicates
 * where to place the logged data.
 */
STATIC void
xlog_recover_do_reg_buffer(
	struct xfs_mount	*mp,
	xlog_recover_item_t	*item,
	struct xfs_buf		*bp,
	xfs_buf_log_format_t	*buf_f,
	xfs_lsn_t		current_lsn)
{
	int			i;
	int			bit;
	int			nbits;
	xfs_failaddr_t		fa;

	trace_xfs_log_recover_buf_reg_buf(mp->m_log, buf_f);

	bit = 0;
	i = 1;  /* 0 is the buf format structure */
	while (1) {
		bit = xfs_next_bit(buf_f->blf_data_map,
				   buf_f->blf_map_size, bit);
		if (bit == -1)
			break;
		nbits = xfs_contig_bits(buf_f->blf_data_map,
					buf_f->blf_map_size, bit);
		ASSERT(nbits > 0);
		ASSERT(item->ri_buf[i].i_addr != NULL);
		ASSERT(item->ri_buf[i].i_len % XFS_BLF_CHUNK == 0);
		ASSERT(BBTOB(bp->b_io_length) >=
		       ((uint)bit << XFS_BLF_SHIFT) + (nbits << XFS_BLF_SHIFT));

		/*
		 * The dirty regions logged in the buffer, even though
		 * contiguous, may span multiple chunks. This is because the
		 * dirty region may span a physical page boundary in a buffer
		 * and hence be split into two separate vectors for writing into
		 * the log. Hence we need to trim nbits back to the length of
		 * the current region being copied out of the log.
		 */
		if (item->ri_buf[i].i_len < (nbits << XFS_BLF_SHIFT))
			nbits = item->ri_buf[i].i_len >> XFS_BLF_SHIFT;

		/*
		 * Do a sanity check if this is a dquot buffer. Just checking
		 * the first dquot in the buffer should do. XXXThis is
		 * probably a good thing to do for other buf types also.
		 */
		fa = NULL;
		if (buf_f->blf_flags &
		   (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
			if (item->ri_buf[i].i_addr == NULL) {
				xfs_alert(mp,
					"XFS: NULL dquot in %s.", __func__);
				goto next;
			}
			if (item->ri_buf[i].i_len < sizeof(xfs_disk_dquot_t)) {
				xfs_alert(mp,
					"XFS: dquot too small (%d) in %s.",
					item->ri_buf[i].i_len, __func__);
				goto next;
			}
			fa = xfs_dquot_verify(mp, item->ri_buf[i].i_addr,
					       -1, 0);
			if (fa) {
				xfs_alert(mp,
	"dquot corrupt at %pS trying to replay into block 0x%llx",
					fa, bp->b_bn);
				goto next;
			}
		}

		memcpy(xfs_buf_offset(bp,
			(uint)bit << XFS_BLF_SHIFT),	/* dest */
			item->ri_buf[i].i_addr,		/* source */
			nbits<<XFS_BLF_SHIFT);		/* length */
 next:
		i++;
		bit += nbits;
	}

	/* Shouldn't be any more regions */
	ASSERT(i == item->ri_total);

	xlog_recover_validate_buf_type(mp, bp, buf_f, current_lsn);
}

/*
 * Perform a dquot buffer recovery.
 * Simple algorithm: if we have found a QUOTAOFF log item of the same type
 * (ie. USR or GRP), then just toss this buffer away; don't recover it.
 * Else, treat it as a regular buffer and do recovery.
 *
 * Return false if the buffer was tossed and true if we recovered the buffer to
 * indicate to the caller if the buffer needs writing.
 */
STATIC bool
xlog_recover_do_dquot_buffer(
	struct xfs_mount		*mp,
	struct xlog			*log,
	struct xlog_recover_item	*item,
	struct xfs_buf			*bp,
	struct xfs_buf_log_format	*buf_f)
{
	uint			type;

	trace_xfs_log_recover_buf_dquot_buf(log, buf_f);

	/*
	 * Filesystems are required to send in quota flags at mount time.
	 */
	if (!mp->m_qflags)
		return false;

	type = 0;
	if (buf_f->blf_flags & XFS_BLF_UDQUOT_BUF)
		type |= XFS_DQ_USER;
	if (buf_f->blf_flags & XFS_BLF_PDQUOT_BUF)
		type |= XFS_DQ_PROJ;
	if (buf_f->blf_flags & XFS_BLF_GDQUOT_BUF)
		type |= XFS_DQ_GROUP;
	/*
	 * This type of quotas was turned off, so ignore this buffer
	 */
	if (log->l_quotaoffs_flag & type)
		return false;

	xlog_recover_do_reg_buffer(mp, item, bp, buf_f, NULLCOMMITLSN);
	return true;
}

/*
 * This routine replays a modification made to a buffer at runtime.
 * There are actually two types of buffer, regular and inode, which
 * are handled differently.  Inode buffers are handled differently
 * in that we only recover a specific set of data from them, namely
 * the inode di_next_unlinked fields.  This is because all other inode
 * data is actually logged via inode records and any data we replay
 * here which overlaps that may be stale.
 *
 * When meta-data buffers are freed at run time we log a buffer item
 * with the XFS_BLF_CANCEL bit set to indicate that previous copies
 * of the buffer in the log should not be replayed at recovery time.
 * This is so that if the blocks covered by the buffer are reused for
 * file data before we crash we don't end up replaying old, freed
 * meta-data into a user's file.
 *
 * To handle the cancellation of buffer log items, we make two passes
 * over the log during recovery.  During the first we build a table of
 * those buffers which have been cancelled, and during the second we
 * only replay those buffers which do not have corresponding cancel
 * records in the table.  See xlog_recover_buffer_pass[1,2] above
 * for more details on the implementation of the table of cancel records.
 */
STATIC int
xlog_recover_buffer_pass2(
	struct xlog			*log,
	struct list_head		*buffer_list,
	struct xlog_recover_item	*item,
	xfs_lsn_t			current_lsn)
{
	xfs_buf_log_format_t	*buf_f = item->ri_buf[0].i_addr;
	xfs_mount_t		*mp = log->l_mp;
	xfs_buf_t		*bp;
	int			error;
	uint			buf_flags;
	xfs_lsn_t		lsn;

	/*
	 * In this pass we only want to recover all the buffers which have
	 * not been cancelled and are not cancellation buffers themselves.
	 */
	if (xlog_check_buffer_cancelled(log, buf_f->blf_blkno,
			buf_f->blf_len, buf_f->blf_flags)) {
		trace_xfs_log_recover_buf_cancel(log, buf_f);
		return 0;
	}

	trace_xfs_log_recover_buf_recover(log, buf_f);

	buf_flags = 0;
	if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
		buf_flags |= XBF_UNMAPPED;

	bp = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
			  buf_flags, NULL);
	if (!bp)
		return -ENOMEM;
	error = bp->b_error;
	if (error) {
		xfs_buf_ioerror_alert(bp, "xlog_recover_do..(read#1)");
		goto out_release;
	}

	/*
	 * Recover the buffer only if we get an LSN from it and it's less than
	 * the lsn of the transaction we are replaying.
	 *
	 * Note that we have to be extremely careful of readahead here.
	 * Readahead does not attach verfiers to the buffers so if we don't
	 * actually do any replay after readahead because of the LSN we found
	 * in the buffer if more recent than that current transaction then we
	 * need to attach the verifier directly. Failure to do so can lead to
	 * future recovery actions (e.g. EFI and unlinked list recovery) can
	 * operate on the buffers and they won't get the verifier attached. This
	 * can lead to blocks on disk having the correct content but a stale
	 * CRC.
	 *
	 * It is safe to assume these clean buffers are currently up to date.
	 * If the buffer is dirtied by a later transaction being replayed, then
	 * the verifier will be reset to match whatever recover turns that
	 * buffer into.
	 */
	lsn = xlog_recover_get_buf_lsn(mp, bp);
	if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
		trace_xfs_log_recover_buf_skip(log, buf_f);
		xlog_recover_validate_buf_type(mp, bp, buf_f, NULLCOMMITLSN);
		goto out_release;
	}

	if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
		error = xlog_recover_do_inode_buffer(mp, item, bp, buf_f);
		if (error)
			goto out_release;
	} else if (buf_f->blf_flags &
		  (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
		bool	dirty;

		dirty = xlog_recover_do_dquot_buffer(mp, log, item, bp, buf_f);
		if (!dirty)
			goto out_release;
	} else {
		xlog_recover_do_reg_buffer(mp, item, bp, buf_f, current_lsn);
	}

	/*
	 * Perform delayed write on the buffer.  Asynchronous writes will be
	 * slower when taking into account all the buffers to be flushed.
	 *
	 * Also make sure that only inode buffers with good sizes stay in
	 * the buffer cache.  The kernel moves inodes in buffers of 1 block
	 * or mp->m_inode_cluster_size bytes, whichever is bigger.  The inode
	 * buffers in the log can be a different size if the log was generated
	 * by an older kernel using unclustered inode buffers or a newer kernel
	 * running with a different inode cluster size.  Regardless, if the
	 * the inode buffer size isn't MAX(blocksize, mp->m_inode_cluster_size)
	 * for *our* value of mp->m_inode_cluster_size, then we need to keep
	 * the buffer out of the buffer cache so that the buffer won't
	 * overlap with future reads of those inodes.
	 */
	if (XFS_DINODE_MAGIC ==
	    be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
	    (BBTOB(bp->b_io_length) != MAX(log->l_mp->m_sb.sb_blocksize,
			(uint32_t)log->l_mp->m_inode_cluster_size))) {
		xfs_buf_stale(bp);
		error = xfs_bwrite(bp);
	} else {
		ASSERT(bp->b_target->bt_mount == mp);
		bp->b_iodone = xlog_recover_iodone;
		xfs_buf_delwri_queue(bp, buffer_list);
	}

out_release:
	xfs_buf_relse(bp);
	return error;
}

/*
 * Inode fork owner changes
 *
 * If we have been told that we have to reparent the inode fork, it's because an
 * extent swap operation on a CRC enabled filesystem has been done and we are
 * replaying it. We need to walk the BMBT of the appropriate fork and change the
 * owners of it.
 *
 * The complexity here is that we don't have an inode context to work with, so
 * after we've replayed the inode we need to instantiate one.  This is where the
 * fun begins.
 *
 * We are in the middle of log recovery, so we can't run transactions. That
 * means we cannot use cache coherent inode instantiation via xfs_iget(), as
 * that will result in the corresponding iput() running the inode through
 * xfs_inactive(). If we've just replayed an inode core that changes the link
 * count to zero (i.e. it's been unlinked), then xfs_inactive() will run
 * transactions (bad!).
 *
 * So, to avoid this, we instantiate an inode directly from the inode core we've
 * just recovered. We have the buffer still locked, and all we really need to
 * instantiate is the inode core and the forks being modified. We can do this
 * manually, then run the inode btree owner change, and then tear down the
 * xfs_inode without having to run any transactions at all.
 *
 * Also, because we don't have a transaction context available here but need to
 * gather all the buffers we modify for writeback so we pass the buffer_list
 * instead for the operation to use.
 */

STATIC int
xfs_recover_inode_owner_change(
	struct xfs_mount	*mp,
	struct xfs_dinode	*dip,
	struct xfs_inode_log_format *in_f,
	struct list_head	*buffer_list)
{
	struct xfs_inode	*ip;
	int			error;

	ASSERT(in_f->ilf_fields & (XFS_ILOG_DOWNER|XFS_ILOG_AOWNER));

	ip = xfs_inode_alloc(mp, in_f->ilf_ino);
	if (!ip)
		return -ENOMEM;

	/* instantiate the inode */
	xfs_inode_from_disk(ip, dip);
	ASSERT(ip->i_d.di_version >= 3);

	error = xfs_iformat_fork(ip, dip);
	if (error)
		goto out_free_ip;

	if (!xfs_inode_verify_forks(ip)) {
		error = -EFSCORRUPTED;
		goto out_free_ip;
	}

	if (in_f->ilf_fields & XFS_ILOG_DOWNER) {
		ASSERT(in_f->ilf_fields & XFS_ILOG_DBROOT);
		error = xfs_bmbt_change_owner(NULL, ip, XFS_DATA_FORK,
					      ip->i_ino, buffer_list);
		if (error)
			goto out_free_ip;
	}

	if (in_f->ilf_fields & XFS_ILOG_AOWNER) {
		ASSERT(in_f->ilf_fields & XFS_ILOG_ABROOT);
		error = xfs_bmbt_change_owner(NULL, ip, XFS_ATTR_FORK,
					      ip->i_ino, buffer_list);
		if (error)
			goto out_free_ip;
	}

out_free_ip:
	xfs_inode_free(ip);
	return error;
}

STATIC int
xlog_recover_inode_pass2(
	struct xlog			*log,
	struct list_head		*buffer_list,
	struct xlog_recover_item	*item,
	xfs_lsn_t			current_lsn)
{
	struct xfs_inode_log_format	*in_f;
	xfs_mount_t		*mp = log->l_mp;
	xfs_buf_t		*bp;
	xfs_dinode_t		*dip;
	int			len;
	char			*src;
	char			*dest;
	int			error;
	int			attr_index;
	uint			fields;
	struct xfs_log_dinode	*ldip;
	uint			isize;
	int			need_free = 0;

	if (item->ri_buf[0].i_len == sizeof(struct xfs_inode_log_format)) {
		in_f = item->ri_buf[0].i_addr;
	} else {
		in_f = kmem_alloc(sizeof(struct xfs_inode_log_format), KM_SLEEP);
		need_free = 1;
		error = xfs_inode_item_format_convert(&item->ri_buf[0], in_f);
		if (error)
			goto error;
	}

	/*
	 * Inode buffers can be freed, look out for it,
	 * and do not replay the inode.
	 */
	if (xlog_check_buffer_cancelled(log, in_f->ilf_blkno,
					in_f->ilf_len, 0)) {
		error = 0;
		trace_xfs_log_recover_inode_cancel(log, in_f);
		goto error;
	}
	trace_xfs_log_recover_inode_recover(log, in_f);

	bp = xfs_buf_read(mp->m_ddev_targp, in_f->ilf_blkno, in_f->ilf_len, 0,
			  &xfs_inode_buf_ops);
	if (!bp) {
		error = -ENOMEM;
		goto error;
	}
	error = bp->b_error;
	if (error) {
		xfs_buf_ioerror_alert(bp, "xlog_recover_do..(read#2)");
		goto out_release;
	}
	ASSERT(in_f->ilf_fields & XFS_ILOG_CORE);
	dip = xfs_buf_offset(bp, in_f->ilf_boffset);

	/*
	 * Make sure the place we're flushing out to really looks
	 * like an inode!
	 */
	if (unlikely(dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))) {
		xfs_alert(mp,
	"%s: Bad inode magic number, dip = "PTR_FMT", dino bp = "PTR_FMT", ino = %Ld",
			__func__, dip, bp, in_f->ilf_ino);
		XFS_ERROR_REPORT("xlog_recover_inode_pass2(1)",
				 XFS_ERRLEVEL_LOW, mp);
		error = -EFSCORRUPTED;
		goto out_release;
	}
	ldip = item->ri_buf[1].i_addr;
	if (unlikely(ldip->di_magic != XFS_DINODE_MAGIC)) {
		xfs_alert(mp,
			"%s: Bad inode log record, rec ptr "PTR_FMT", ino %Ld",
			__func__, item, in_f->ilf_ino);
		XFS_ERROR_REPORT("xlog_recover_inode_pass2(2)",
				 XFS_ERRLEVEL_LOW, mp);
		error = -EFSCORRUPTED;
		goto out_release;
	}

	/*
	 * If the inode has an LSN in it, recover the inode only if it's less
	 * than the lsn of the transaction we are replaying. Note: we still
	 * need to replay an owner change even though the inode is more recent
	 * than the transaction as there is no guarantee that all the btree
	 * blocks are more recent than this transaction, too.
	 */
	if (dip->di_version >= 3) {
		xfs_lsn_t	lsn = be64_to_cpu(dip->di_lsn);

		if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
			trace_xfs_log_recover_inode_skip(log, in_f);
			error = 0;
			goto out_owner_change;
		}
	}

	/*
	 * di_flushiter is only valid for v1/2 inodes. All changes for v3 inodes
	 * are transactional and if ordering is necessary we can determine that
	 * more accurately by the LSN field in the V3 inode core. Don't trust
	 * the inode versions we might be changing them here - use the
	 * superblock flag to determine whether we need to look at di_flushiter
	 * to skip replay when the on disk inode is newer than the log one
	 */
	if (!xfs_sb_version_hascrc(&mp->m_sb) &&
	    ldip->di_flushiter < be16_to_cpu(dip->di_flushiter)) {
		/*
		 * Deal with the wrap case, DI_MAX_FLUSH is less
		 * than smaller numbers
		 */
		if (be16_to_cpu(dip->di_flushiter) == DI_MAX_FLUSH &&
		    ldip->di_flushiter < (DI_MAX_FLUSH >> 1)) {
			/* do nothing */
		} else {
			trace_xfs_log_recover_inode_skip(log, in_f);
			error = 0;
			goto out_release;
		}
	}

	/* Take the opportunity to reset the flush iteration count */
	ldip->di_flushiter = 0;

	if (unlikely(S_ISREG(ldip->di_mode))) {
		if ((ldip->di_format != XFS_DINODE_FMT_EXTENTS) &&
		    (ldip->di_format != XFS_DINODE_FMT_BTREE)) {
			XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(3)",
					 XFS_ERRLEVEL_LOW, mp, ldip,
					 sizeof(*ldip));
			xfs_alert(mp,
		"%s: Bad regular inode log record, rec ptr "PTR_FMT", "
		"ino ptr = "PTR_FMT", ino bp = "PTR_FMT", ino %Ld",
				__func__, item, dip, bp, in_f->ilf_ino);
			error = -EFSCORRUPTED;
			goto out_release;
		}
	} else if (unlikely(S_ISDIR(ldip->di_mode))) {
		if ((ldip->di_format != XFS_DINODE_FMT_EXTENTS) &&
		    (ldip->di_format != XFS_DINODE_FMT_BTREE) &&
		    (ldip->di_format != XFS_DINODE_FMT_LOCAL)) {
			XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(4)",
					     XFS_ERRLEVEL_LOW, mp, ldip,
					     sizeof(*ldip));
			xfs_alert(mp,
		"%s: Bad dir inode log record, rec ptr "PTR_FMT", "
		"ino ptr = "PTR_FMT", ino bp = "PTR_FMT", ino %Ld",
				__func__, item, dip, bp, in_f->ilf_ino);
			error = -EFSCORRUPTED;
			goto out_release;
		}
	}
	if (unlikely(ldip->di_nextents + ldip->di_anextents > ldip->di_nblocks)){
		XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(5)",
				     XFS_ERRLEVEL_LOW, mp, ldip,
				     sizeof(*ldip));
		xfs_alert(mp,
	"%s: Bad inode log record, rec ptr "PTR_FMT", dino ptr "PTR_FMT", "
	"dino bp "PTR_FMT", ino %Ld, total extents = %d, nblocks = %Ld",
			__func__, item, dip, bp, in_f->ilf_ino,
			ldip->di_nextents + ldip->di_anextents,
			ldip->di_nblocks);
		error = -EFSCORRUPTED;
		goto out_release;
	}
	if (unlikely(ldip->di_forkoff > mp->m_sb.sb_inodesize)) {
		XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(6)",
				     XFS_ERRLEVEL_LOW, mp, ldip,
				     sizeof(*ldip));
		xfs_alert(mp,
	"%s: Bad inode log record, rec ptr "PTR_FMT", dino ptr "PTR_FMT", "
	"dino bp "PTR_FMT", ino %Ld, forkoff 0x%x", __func__,
			item, dip, bp, in_f->ilf_ino, ldip->di_forkoff);
		error = -EFSCORRUPTED;
		goto out_release;
	}
	isize = xfs_log_dinode_size(ldip->di_version);
	if (unlikely(item->ri_buf[1].i_len > isize)) {
		XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(7)",
				     XFS_ERRLEVEL_LOW, mp, ldip,
				     sizeof(*ldip));
		xfs_alert(mp,
			"%s: Bad inode log record length %d, rec ptr "PTR_FMT,
			__func__, item->ri_buf[1].i_len, item);
		error = -EFSCORRUPTED;
		goto out_release;
	}

	/* recover the log dinode inode into the on disk inode */
	xfs_log_dinode_to_disk(ldip, dip);

	fields = in_f->ilf_fields;
	if (fields & XFS_ILOG_DEV)
		xfs_dinode_put_rdev(dip, in_f->ilf_u.ilfu_rdev);

	if (in_f->ilf_size == 2)
		goto out_owner_change;
	len = item->ri_buf[2].i_len;
	src = item->ri_buf[2].i_addr;
	ASSERT(in_f->ilf_size <= 4);
	ASSERT((in_f->ilf_size == 3) || (fields & XFS_ILOG_AFORK));
	ASSERT(!(fields & XFS_ILOG_DFORK) ||
	       (len == in_f->ilf_dsize));

	switch (fields & XFS_ILOG_DFORK) {
	case XFS_ILOG_DDATA:
	case XFS_ILOG_DEXT:
		memcpy(XFS_DFORK_DPTR(dip), src, len);
		break;

	case XFS_ILOG_DBROOT:
		xfs_bmbt_to_bmdr(mp, (struct xfs_btree_block *)src, len,
				 (xfs_bmdr_block_t *)XFS_DFORK_DPTR(dip),
				 XFS_DFORK_DSIZE(dip, mp));
		break;

	default:
		/*
		 * There are no data fork flags set.
		 */
		ASSERT((fields & XFS_ILOG_DFORK) == 0);
		break;
	}

	/*
	 * If we logged any attribute data, recover it.  There may or
	 * may not have been any other non-core data logged in this
	 * transaction.
	 */
	if (in_f->ilf_fields & XFS_ILOG_AFORK) {
		if (in_f->ilf_fields & XFS_ILOG_DFORK) {
			attr_index = 3;
		} else {
			attr_index = 2;
		}
		len = item->ri_buf[attr_index].i_len;
		src = item->ri_buf[attr_index].i_addr;
		ASSERT(len == in_f->ilf_asize);

		switch (in_f->ilf_fields & XFS_ILOG_AFORK) {
		case XFS_ILOG_ADATA:
		case XFS_ILOG_AEXT:
			dest = XFS_DFORK_APTR(dip);
			ASSERT(len <= XFS_DFORK_ASIZE(dip, mp));
			memcpy(dest, src, len);
			break;

		case XFS_ILOG_ABROOT:
			dest = XFS_DFORK_APTR(dip);
			xfs_bmbt_to_bmdr(mp, (struct xfs_btree_block *)src,
					 len, (xfs_bmdr_block_t*)dest,
					 XFS_DFORK_ASIZE(dip, mp));
			break;

		default:
			xfs_warn(log->l_mp, "%s: Invalid flag", __func__);
			ASSERT(0);
			error = -EIO;
			goto out_release;
		}
	}

out_owner_change:
	/* Recover the swapext owner change unless inode has been deleted */
	if ((in_f->ilf_fields & (XFS_ILOG_DOWNER|XFS_ILOG_AOWNER)) &&
	    (dip->di_mode != 0))
		error = xfs_recover_inode_owner_change(mp, dip, in_f,
						       buffer_list);
	/* re-generate the checksum. */
	xfs_dinode_calc_crc(log->l_mp, dip);

	ASSERT(bp->b_target->bt_mount == mp);
	bp->b_iodone = xlog_recover_iodone;
	xfs_buf_delwri_queue(bp, buffer_list);

out_release:
	xfs_buf_relse(bp);
error:
	if (need_free)
		kmem_free(in_f);
	return error;
}

/*
 * Recover QUOTAOFF records. We simply make a note of it in the xlog
 * structure, so that we know not to do any dquot item or dquot buffer recovery,
 * of that type.
 */
STATIC int
xlog_recover_quotaoff_pass1(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	xfs_qoff_logformat_t	*qoff_f = item->ri_buf[0].i_addr;
	ASSERT(qoff_f);

	/*
	 * The logitem format's flag tells us if this was user quotaoff,
	 * group/project quotaoff or both.
	 */
	if (qoff_f->qf_flags & XFS_UQUOTA_ACCT)
		log->l_quotaoffs_flag |= XFS_DQ_USER;
	if (qoff_f->qf_flags & XFS_PQUOTA_ACCT)
		log->l_quotaoffs_flag |= XFS_DQ_PROJ;
	if (qoff_f->qf_flags & XFS_GQUOTA_ACCT)
		log->l_quotaoffs_flag |= XFS_DQ_GROUP;

	return 0;
}

/*
 * Recover a dquot record
 */
STATIC int
xlog_recover_dquot_pass2(
	struct xlog			*log,
	struct list_head		*buffer_list,
	struct xlog_recover_item	*item,
	xfs_lsn_t			current_lsn)
{
	xfs_mount_t		*mp = log->l_mp;
	xfs_buf_t		*bp;
	struct xfs_disk_dquot	*ddq, *recddq;
	xfs_failaddr_t		fa;
	int			error;
	xfs_dq_logformat_t	*dq_f;
	uint			type;


	/*
	 * Filesystems are required to send in quota flags at mount time.
	 */
	if (mp->m_qflags == 0)
		return 0;

	recddq = item->ri_buf[1].i_addr;
	if (recddq == NULL) {
		xfs_alert(log->l_mp, "NULL dquot in %s.", __func__);
		return -EIO;
	}
	if (item->ri_buf[1].i_len < sizeof(xfs_disk_dquot_t)) {
		xfs_alert(log->l_mp, "dquot too small (%d) in %s.",
			item->ri_buf[1].i_len, __func__);
		return -EIO;
	}

	/*
	 * This type of quotas was turned off, so ignore this record.
	 */
	type = recddq->d_flags & (XFS_DQ_USER | XFS_DQ_PROJ | XFS_DQ_GROUP);
	ASSERT(type);
	if (log->l_quotaoffs_flag & type)
		return 0;

	/*
	 * At this point we know that quota was _not_ turned off.
	 * Since the mount flags are not indicating to us otherwise, this
	 * must mean that quota is on, and the dquot needs to be replayed.
	 * Remember that we may not have fully recovered the superblock yet,
	 * so we can't do the usual trick of looking at the SB quota bits.
	 *
	 * The other possibility, of course, is that the quota subsystem was
	 * removed since the last mount - ENOSYS.
	 */
	dq_f = item->ri_buf[0].i_addr;
	ASSERT(dq_f);
	fa = xfs_dquot_verify(mp, recddq, dq_f->qlf_id, 0);
	if (fa) {
		xfs_alert(mp, "corrupt dquot ID 0x%x in log at %pS",
				dq_f->qlf_id, fa);
		return -EIO;
	}
	ASSERT(dq_f->qlf_len == 1);

	/*
	 * At this point we are assuming that the dquots have been allocated
	 * and hence the buffer has valid dquots stamped in it. It should,
	 * therefore, pass verifier validation. If the dquot is bad, then the
	 * we'll return an error here, so we don't need to specifically check
	 * the dquot in the buffer after the verifier has run.
	 */
	error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dq_f->qlf_blkno,
				   XFS_FSB_TO_BB(mp, dq_f->qlf_len), 0, &bp,
				   &xfs_dquot_buf_ops);
	if (error)
		return error;

	ASSERT(bp);
	ddq = xfs_buf_offset(bp, dq_f->qlf_boffset);

	/*
	 * If the dquot has an LSN in it, recover the dquot only if it's less
	 * than the lsn of the transaction we are replaying.
	 */
	if (xfs_sb_version_hascrc(&mp->m_sb)) {
		struct xfs_dqblk *dqb = (struct xfs_dqblk *)ddq;
		xfs_lsn_t	lsn = be64_to_cpu(dqb->dd_lsn);

		if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
			goto out_release;
		}
	}

	memcpy(ddq, recddq, item->ri_buf[1].i_len);
	if (xfs_sb_version_hascrc(&mp->m_sb)) {
		xfs_update_cksum((char *)ddq, sizeof(struct xfs_dqblk),
				 XFS_DQUOT_CRC_OFF);
	}

	ASSERT(dq_f->qlf_size == 2);
	ASSERT(bp->b_target->bt_mount == mp);
	bp->b_iodone = xlog_recover_iodone;
	xfs_buf_delwri_queue(bp, buffer_list);

out_release:
	xfs_buf_relse(bp);
	return 0;
}

/*
 * This routine is called to create an in-core extent free intent
 * item from the efi format structure which was logged on disk.
 * It allocates an in-core efi, copies the extents from the format
 * structure into it, and adds the efi to the AIL with the given
 * LSN.
 */
STATIC int
xlog_recover_efi_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item,
	xfs_lsn_t			lsn)
{
	int				error;
	struct xfs_mount		*mp = log->l_mp;
	struct xfs_efi_log_item		*efip;
	struct xfs_efi_log_format	*efi_formatp;

	efi_formatp = item->ri_buf[0].i_addr;

	efip = xfs_efi_init(mp, efi_formatp->efi_nextents);
	error = xfs_efi_copy_format(&item->ri_buf[0], &efip->efi_format);
	if (error) {
		xfs_efi_item_free(efip);
		return error;
	}
	atomic_set(&efip->efi_next_extent, efi_formatp->efi_nextents);

	spin_lock(&log->l_ailp->ail_lock);
	/*
	 * The EFI has two references. One for the EFD and one for EFI to ensure
	 * it makes it into the AIL. Insert the EFI into the AIL directly and
	 * drop the EFI reference. Note that xfs_trans_ail_update() drops the
	 * AIL lock.
	 */
	xfs_trans_ail_update(log->l_ailp, &efip->efi_item, lsn);
	xfs_efi_release(efip);
	return 0;
}


/*
 * This routine is called when an EFD format structure is found in a committed
 * transaction in the log. Its purpose is to cancel the corresponding EFI if it
 * was still in the log. To do this it searches the AIL for the EFI with an id
 * equal to that in the EFD format structure. If we find it we drop the EFD
 * reference, which removes the EFI from the AIL and frees it.
 */
STATIC int
xlog_recover_efd_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	xfs_efd_log_format_t	*efd_formatp;
	xfs_efi_log_item_t	*efip = NULL;
	xfs_log_item_t		*lip;
	uint64_t		efi_id;
	struct xfs_ail_cursor	cur;
	struct xfs_ail		*ailp = log->l_ailp;

	efd_formatp = item->ri_buf[0].i_addr;
	ASSERT((item->ri_buf[0].i_len == (sizeof(xfs_efd_log_format_32_t) +
		((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_32_t)))) ||
	       (item->ri_buf[0].i_len == (sizeof(xfs_efd_log_format_64_t) +
		((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_64_t)))));
	efi_id = efd_formatp->efd_efi_id;

	/*
	 * Search for the EFI with the id in the EFD format structure in the
	 * AIL.
	 */
	spin_lock(&ailp->ail_lock);
	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
	while (lip != NULL) {
		if (lip->li_type == XFS_LI_EFI) {
			efip = (xfs_efi_log_item_t *)lip;
			if (efip->efi_format.efi_id == efi_id) {
				/*
				 * Drop the EFD reference to the EFI. This
				 * removes the EFI from the AIL and frees it.
				 */
				spin_unlock(&ailp->ail_lock);
				xfs_efi_release(efip);
				spin_lock(&ailp->ail_lock);
				break;
			}
		}
		lip = xfs_trans_ail_cursor_next(ailp, &cur);
	}

	xfs_trans_ail_cursor_done(&cur);
	spin_unlock(&ailp->ail_lock);

	return 0;
}

/*
 * This routine is called to create an in-core extent rmap update
 * item from the rui format structure which was logged on disk.
 * It allocates an in-core rui, copies the extents from the format
 * structure into it, and adds the rui to the AIL with the given
 * LSN.
 */
STATIC int
xlog_recover_rui_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item,
	xfs_lsn_t			lsn)
{
	int				error;
	struct xfs_mount		*mp = log->l_mp;
	struct xfs_rui_log_item		*ruip;
	struct xfs_rui_log_format	*rui_formatp;

	rui_formatp = item->ri_buf[0].i_addr;

	ruip = xfs_rui_init(mp, rui_formatp->rui_nextents);
	error = xfs_rui_copy_format(&item->ri_buf[0], &ruip->rui_format);
	if (error) {
		xfs_rui_item_free(ruip);
		return error;
	}
	atomic_set(&ruip->rui_next_extent, rui_formatp->rui_nextents);

	spin_lock(&log->l_ailp->ail_lock);
	/*
	 * The RUI has two references. One for the RUD and one for RUI to ensure
	 * it makes it into the AIL. Insert the RUI into the AIL directly and
	 * drop the RUI reference. Note that xfs_trans_ail_update() drops the
	 * AIL lock.
	 */
	xfs_trans_ail_update(log->l_ailp, &ruip->rui_item, lsn);
	xfs_rui_release(ruip);
	return 0;
}


/*
 * This routine is called when an RUD format structure is found in a committed
 * transaction in the log. Its purpose is to cancel the corresponding RUI if it
 * was still in the log. To do this it searches the AIL for the RUI with an id
 * equal to that in the RUD format structure. If we find it we drop the RUD
 * reference, which removes the RUI from the AIL and frees it.
 */
STATIC int
xlog_recover_rud_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	struct xfs_rud_log_format	*rud_formatp;
	struct xfs_rui_log_item		*ruip = NULL;
	struct xfs_log_item		*lip;
	uint64_t			rui_id;
	struct xfs_ail_cursor		cur;
	struct xfs_ail			*ailp = log->l_ailp;

	rud_formatp = item->ri_buf[0].i_addr;
	ASSERT(item->ri_buf[0].i_len == sizeof(struct xfs_rud_log_format));
	rui_id = rud_formatp->rud_rui_id;

	/*
	 * Search for the RUI with the id in the RUD format structure in the
	 * AIL.
	 */
	spin_lock(&ailp->ail_lock);
	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
	while (lip != NULL) {
		if (lip->li_type == XFS_LI_RUI) {
			ruip = (struct xfs_rui_log_item *)lip;
			if (ruip->rui_format.rui_id == rui_id) {
				/*
				 * Drop the RUD reference to the RUI. This
				 * removes the RUI from the AIL and frees it.
				 */
				spin_unlock(&ailp->ail_lock);
				xfs_rui_release(ruip);
				spin_lock(&ailp->ail_lock);
				break;
			}
		}
		lip = xfs_trans_ail_cursor_next(ailp, &cur);
	}

	xfs_trans_ail_cursor_done(&cur);
	spin_unlock(&ailp->ail_lock);

	return 0;
}

/*
 * Copy an CUI format buffer from the given buf, and into the destination
 * CUI format structure.  The CUI/CUD items were designed not to need any
 * special alignment handling.
 */
static int
xfs_cui_copy_format(
	struct xfs_log_iovec		*buf,
	struct xfs_cui_log_format	*dst_cui_fmt)
{
	struct xfs_cui_log_format	*src_cui_fmt;
	uint				len;

	src_cui_fmt = buf->i_addr;
	len = xfs_cui_log_format_sizeof(src_cui_fmt->cui_nextents);

	if (buf->i_len == len) {
		memcpy(dst_cui_fmt, src_cui_fmt, len);
		return 0;
	}
	return -EFSCORRUPTED;
}

/*
 * This routine is called to create an in-core extent refcount update
 * item from the cui format structure which was logged on disk.
 * It allocates an in-core cui, copies the extents from the format
 * structure into it, and adds the cui to the AIL with the given
 * LSN.
 */
STATIC int
xlog_recover_cui_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item,
	xfs_lsn_t			lsn)
{
	int				error;
	struct xfs_mount		*mp = log->l_mp;
	struct xfs_cui_log_item		*cuip;
	struct xfs_cui_log_format	*cui_formatp;

	cui_formatp = item->ri_buf[0].i_addr;

	cuip = xfs_cui_init(mp, cui_formatp->cui_nextents);
	error = xfs_cui_copy_format(&item->ri_buf[0], &cuip->cui_format);
	if (error) {
		xfs_cui_item_free(cuip);
		return error;
	}
	atomic_set(&cuip->cui_next_extent, cui_formatp->cui_nextents);

	spin_lock(&log->l_ailp->ail_lock);
	/*
	 * The CUI has two references. One for the CUD and one for CUI to ensure
	 * it makes it into the AIL. Insert the CUI into the AIL directly and
	 * drop the CUI reference. Note that xfs_trans_ail_update() drops the
	 * AIL lock.
	 */
	xfs_trans_ail_update(log->l_ailp, &cuip->cui_item, lsn);
	xfs_cui_release(cuip);
	return 0;
}


/*
 * This routine is called when an CUD format structure is found in a committed
 * transaction in the log. Its purpose is to cancel the corresponding CUI if it
 * was still in the log. To do this it searches the AIL for the CUI with an id
 * equal to that in the CUD format structure. If we find it we drop the CUD
 * reference, which removes the CUI from the AIL and frees it.
 */
STATIC int
xlog_recover_cud_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	struct xfs_cud_log_format	*cud_formatp;
	struct xfs_cui_log_item		*cuip = NULL;
	struct xfs_log_item		*lip;
	uint64_t			cui_id;
	struct xfs_ail_cursor		cur;
	struct xfs_ail			*ailp = log->l_ailp;

	cud_formatp = item->ri_buf[0].i_addr;
	if (item->ri_buf[0].i_len != sizeof(struct xfs_cud_log_format))
		return -EFSCORRUPTED;
	cui_id = cud_formatp->cud_cui_id;

	/*
	 * Search for the CUI with the id in the CUD format structure in the
	 * AIL.
	 */
	spin_lock(&ailp->ail_lock);
	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
	while (lip != NULL) {
		if (lip->li_type == XFS_LI_CUI) {
			cuip = (struct xfs_cui_log_item *)lip;
			if (cuip->cui_format.cui_id == cui_id) {
				/*
				 * Drop the CUD reference to the CUI. This
				 * removes the CUI from the AIL and frees it.
				 */
				spin_unlock(&ailp->ail_lock);
				xfs_cui_release(cuip);
				spin_lock(&ailp->ail_lock);
				break;
			}
		}
		lip = xfs_trans_ail_cursor_next(ailp, &cur);
	}

	xfs_trans_ail_cursor_done(&cur);
	spin_unlock(&ailp->ail_lock);

	return 0;
}

/*
 * Copy an BUI format buffer from the given buf, and into the destination
 * BUI format structure.  The BUI/BUD items were designed not to need any
 * special alignment handling.
 */
static int
xfs_bui_copy_format(
	struct xfs_log_iovec		*buf,
	struct xfs_bui_log_format	*dst_bui_fmt)
{
	struct xfs_bui_log_format	*src_bui_fmt;
	uint				len;

	src_bui_fmt = buf->i_addr;
	len = xfs_bui_log_format_sizeof(src_bui_fmt->bui_nextents);

	if (buf->i_len == len) {
		memcpy(dst_bui_fmt, src_bui_fmt, len);
		return 0;
	}
	return -EFSCORRUPTED;
}

/*
 * This routine is called to create an in-core extent bmap update
 * item from the bui format structure which was logged on disk.
 * It allocates an in-core bui, copies the extents from the format
 * structure into it, and adds the bui to the AIL with the given
 * LSN.
 */
STATIC int
xlog_recover_bui_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item,
	xfs_lsn_t			lsn)
{
	int				error;
	struct xfs_mount		*mp = log->l_mp;
	struct xfs_bui_log_item		*buip;
	struct xfs_bui_log_format	*bui_formatp;

	bui_formatp = item->ri_buf[0].i_addr;

	if (bui_formatp->bui_nextents != XFS_BUI_MAX_FAST_EXTENTS)
		return -EFSCORRUPTED;
	buip = xfs_bui_init(mp);
	error = xfs_bui_copy_format(&item->ri_buf[0], &buip->bui_format);
	if (error) {
		xfs_bui_item_free(buip);
		return error;
	}
	atomic_set(&buip->bui_next_extent, bui_formatp->bui_nextents);

	spin_lock(&log->l_ailp->ail_lock);
	/*
	 * The RUI has two references. One for the RUD and one for RUI to ensure
	 * it makes it into the AIL. Insert the RUI into the AIL directly and
	 * drop the RUI reference. Note that xfs_trans_ail_update() drops the
	 * AIL lock.
	 */
	xfs_trans_ail_update(log->l_ailp, &buip->bui_item, lsn);
	xfs_bui_release(buip);
	return 0;
}


/*
 * This routine is called when an BUD format structure is found in a committed
 * transaction in the log. Its purpose is to cancel the corresponding BUI if it
 * was still in the log. To do this it searches the AIL for the BUI with an id
 * equal to that in the BUD format structure. If we find it we drop the BUD
 * reference, which removes the BUI from the AIL and frees it.
 */
STATIC int
xlog_recover_bud_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	struct xfs_bud_log_format	*bud_formatp;
	struct xfs_bui_log_item		*buip = NULL;
	struct xfs_log_item		*lip;
	uint64_t			bui_id;
	struct xfs_ail_cursor		cur;
	struct xfs_ail			*ailp = log->l_ailp;

	bud_formatp = item->ri_buf[0].i_addr;
	if (item->ri_buf[0].i_len != sizeof(struct xfs_bud_log_format))
		return -EFSCORRUPTED;
	bui_id = bud_formatp->bud_bui_id;

	/*
	 * Search for the BUI with the id in the BUD format structure in the
	 * AIL.
	 */
	spin_lock(&ailp->ail_lock);
	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
	while (lip != NULL) {
		if (lip->li_type == XFS_LI_BUI) {
			buip = (struct xfs_bui_log_item *)lip;
			if (buip->bui_format.bui_id == bui_id) {
				/*
				 * Drop the BUD reference to the BUI. This
				 * removes the BUI from the AIL and frees it.
				 */
				spin_unlock(&ailp->ail_lock);
				xfs_bui_release(buip);
				spin_lock(&ailp->ail_lock);
				break;
			}
		}
		lip = xfs_trans_ail_cursor_next(ailp, &cur);
	}

	xfs_trans_ail_cursor_done(&cur);
	spin_unlock(&ailp->ail_lock);

	return 0;
}

/*
 * This routine is called when an inode create format structure is found in a
 * committed transaction in the log.  It's purpose is to initialise the inodes
 * being allocated on disk. This requires us to get inode cluster buffers that
 * match the range to be initialised, stamped with inode templates and written
 * by delayed write so that subsequent modifications will hit the cached buffer
 * and only need writing out at the end of recovery.
 */
STATIC int
xlog_recover_do_icreate_pass2(
	struct xlog		*log,
	struct list_head	*buffer_list,
	xlog_recover_item_t	*item)
{
	struct xfs_mount	*mp = log->l_mp;
	struct xfs_icreate_log	*icl;
	xfs_agnumber_t		agno;
	xfs_agblock_t		agbno;
	unsigned int		count;
	unsigned int		isize;
	xfs_agblock_t		length;
	int			blks_per_cluster;
	int			bb_per_cluster;
	int			cancel_count;
	int			nbufs;
	int			i;

	icl = (struct xfs_icreate_log *)item->ri_buf[0].i_addr;
	if (icl->icl_type != XFS_LI_ICREATE) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad type");
		return -EINVAL;
	}

	if (icl->icl_size != 1) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad icl size");
		return -EINVAL;
	}

	agno = be32_to_cpu(icl->icl_ag);
	if (agno >= mp->m_sb.sb_agcount) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad agno");
		return -EINVAL;
	}
	agbno = be32_to_cpu(icl->icl_agbno);
	if (!agbno || agbno == NULLAGBLOCK || agbno >= mp->m_sb.sb_agblocks) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad agbno");
		return -EINVAL;
	}
	isize = be32_to_cpu(icl->icl_isize);
	if (isize != mp->m_sb.sb_inodesize) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad isize");
		return -EINVAL;
	}
	count = be32_to_cpu(icl->icl_count);
	if (!count) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad count");
		return -EINVAL;
	}
	length = be32_to_cpu(icl->icl_length);
	if (!length || length >= mp->m_sb.sb_agblocks) {
		xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad length");
		return -EINVAL;
	}

	/*
	 * The inode chunk is either full or sparse and we only support
	 * m_ialloc_min_blks sized sparse allocations at this time.
	 */
	if (length != mp->m_ialloc_blks &&
	    length != mp->m_ialloc_min_blks) {
		xfs_warn(log->l_mp,
			 "%s: unsupported chunk length", __FUNCTION__);
		return -EINVAL;
	}

	/* verify inode count is consistent with extent length */
	if ((count >> mp->m_sb.sb_inopblog) != length) {
		xfs_warn(log->l_mp,
			 "%s: inconsistent inode count and chunk length",
			 __FUNCTION__);
		return -EINVAL;
	}

	/*
	 * The icreate transaction can cover multiple cluster buffers and these
	 * buffers could have been freed and reused. Check the individual
	 * buffers for cancellation so we don't overwrite anything written after
	 * a cancellation.
	 */
	blks_per_cluster = xfs_icluster_size_fsb(mp);
	bb_per_cluster = XFS_FSB_TO_BB(mp, blks_per_cluster);
	nbufs = length / blks_per_cluster;
	for (i = 0, cancel_count = 0; i < nbufs; i++) {
		xfs_daddr_t	daddr;

		daddr = XFS_AGB_TO_DADDR(mp, agno,
					 agbno + i * blks_per_cluster);
		if (xlog_check_buffer_cancelled(log, daddr, bb_per_cluster, 0))
			cancel_count++;
	}

	/*
	 * We currently only use icreate for a single allocation at a time. This
	 * means we should expect either all or none of the buffers to be
	 * cancelled. Be conservative and skip replay if at least one buffer is
	 * cancelled, but warn the user that something is awry if the buffers
	 * are not consistent.
	 *
	 * XXX: This must be refined to only skip cancelled clusters once we use
	 * icreate for multiple chunk allocations.
	 */
	ASSERT(!cancel_count || cancel_count == nbufs);
	if (cancel_count) {
		if (cancel_count != nbufs)
			xfs_warn(mp,
	"WARNING: partial inode chunk cancellation, skipped icreate.");
		trace_xfs_log_recover_icreate_cancel(log, icl);
		return 0;
	}

	trace_xfs_log_recover_icreate_recover(log, icl);
	return xfs_ialloc_inode_init(mp, NULL, buffer_list, count, agno, agbno,
				     length, be32_to_cpu(icl->icl_gen));
}

STATIC void
xlog_recover_buffer_ra_pass2(
	struct xlog                     *log,
	struct xlog_recover_item        *item)
{
	struct xfs_buf_log_format	*buf_f = item->ri_buf[0].i_addr;
	struct xfs_mount		*mp = log->l_mp;

	if (xlog_peek_buffer_cancelled(log, buf_f->blf_blkno,
			buf_f->blf_len, buf_f->blf_flags)) {
		return;
	}

	xfs_buf_readahead(mp->m_ddev_targp, buf_f->blf_blkno,
				buf_f->blf_len, NULL);
}

STATIC void
xlog_recover_inode_ra_pass2(
	struct xlog                     *log,
	struct xlog_recover_item        *item)
{
	struct xfs_inode_log_format	ilf_buf;
	struct xfs_inode_log_format	*ilfp;
	struct xfs_mount		*mp = log->l_mp;
	int			error;

	if (item->ri_buf[0].i_len == sizeof(struct xfs_inode_log_format)) {
		ilfp = item->ri_buf[0].i_addr;
	} else {
		ilfp = &ilf_buf;
		memset(ilfp, 0, sizeof(*ilfp));
		error = xfs_inode_item_format_convert(&item->ri_buf[0], ilfp);
		if (error)
			return;
	}

	if (xlog_peek_buffer_cancelled(log, ilfp->ilf_blkno, ilfp->ilf_len, 0))
		return;

	xfs_buf_readahead(mp->m_ddev_targp, ilfp->ilf_blkno,
				ilfp->ilf_len, &xfs_inode_buf_ra_ops);
}

STATIC void
xlog_recover_dquot_ra_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	struct xfs_mount	*mp = log->l_mp;
	struct xfs_disk_dquot	*recddq;
	struct xfs_dq_logformat	*dq_f;
	uint			type;
	int			len;


	if (mp->m_qflags == 0)
		return;

	recddq = item->ri_buf[1].i_addr;
	if (recddq == NULL)
		return;
	if (item->ri_buf[1].i_len < sizeof(struct xfs_disk_dquot))
		return;

	type = recddq->d_flags & (XFS_DQ_USER | XFS_DQ_PROJ | XFS_DQ_GROUP);
	ASSERT(type);
	if (log->l_quotaoffs_flag & type)
		return;

	dq_f = item->ri_buf[0].i_addr;
	ASSERT(dq_f);
	ASSERT(dq_f->qlf_len == 1);

	len = XFS_FSB_TO_BB(mp, dq_f->qlf_len);
	if (xlog_peek_buffer_cancelled(log, dq_f->qlf_blkno, len, 0))
		return;

	xfs_buf_readahead(mp->m_ddev_targp, dq_f->qlf_blkno, len,
			  &xfs_dquot_buf_ra_ops);
}

STATIC void
xlog_recover_ra_pass2(
	struct xlog			*log,
	struct xlog_recover_item	*item)
{
	switch (ITEM_TYPE(item)) {
	case XFS_LI_BUF:
		xlog_recover_buffer_ra_pass2(log, item);
		break;
	case XFS_LI_INODE:
		xlog_recover_inode_ra_pass2(log, item);
		break;
	case XFS_LI_DQUOT:
		xlog_recover_dquot_ra_pass2(log, item);
		break;
	case XFS_LI_EFI:
	case XFS_LI_EFD:
	case XFS_LI_QUOTAOFF:
	case XFS_LI_RUI:
	case XFS_LI_RUD:
	case XFS_LI_CUI:
	case XFS_LI_CUD:
	case XFS_LI_BUI:
	case XFS_LI_BUD:
	default:
		break;
	}
}

STATIC int
xlog_recover_commit_pass1(
	struct xlog			*log,
	struct xlog_recover		*trans,
	struct xlog_recover_item	*item)
{
	trace_xfs_log_recover_item_recover(log, trans, item, XLOG_RECOVER_PASS1);

	switch (ITEM_TYPE(item)) {
	case XFS_LI_BUF:
		return xlog_recover_buffer_pass1(log, item);
	case XFS_LI_QUOTAOFF:
		return xlog_recover_quotaoff_pass1(log, item);
	case XFS_LI_INODE:
	case XFS_LI_EFI:
	case XFS_LI_EFD:
	case XFS_LI_DQUOT:
	case XFS_LI_ICREATE:
	case XFS_LI_RUI:
	case XFS_LI_RUD:
	case XFS_LI_CUI:
	case XFS_LI_CUD:
	case XFS_LI_BUI:
	case XFS_LI_BUD:
		/* nothing to do in pass 1 */
		return 0;
	default:
		xfs_warn(log->l_mp, "%s: invalid item type (%d)",
			__func__, ITEM_TYPE(item));
		ASSERT(0);
		return -EIO;
	}
}

STATIC int
xlog_recover_commit_pass2(
	struct xlog			*log,
	struct xlog_recover		*trans,
	struct list_head		*buffer_list,
	struct xlog_recover_item	*item)
{
	trace_xfs_log_recover_item_recover(log, trans, item, XLOG_RECOVER_PASS2);

	switch (ITEM_TYPE(item)) {
	case XFS_LI_BUF:
		return xlog_recover_buffer_pass2(log, buffer_list, item,
						 trans->r_lsn);
	case XFS_LI_INODE:
		return xlog_recover_inode_pass2(log, buffer_list, item,
						 trans->r_lsn);
	case XFS_LI_EFI:
		return xlog_recover_efi_pass2(log, item, trans->r_lsn);
	case XFS_LI_EFD:
		return xlog_recover_efd_pass2(log, item);
	case XFS_LI_RUI:
		return xlog_recover_rui_pass2(log, item, trans->r_lsn);
	case XFS_LI_RUD:
		return xlog_recover_rud_pass2(log, item);
	case XFS_LI_CUI:
		return xlog_recover_cui_pass2(log, item, trans->r_lsn);
	case XFS_LI_CUD:
		return xlog_recover_cud_pass2(log, item);
	case XFS_LI_BUI:
		return xlog_recover_bui_pass2(log, item, trans->r_lsn);
	case XFS_LI_BUD:
		return xlog_recover_bud_pass2(log, item);
	case XFS_LI_DQUOT:
		return xlog_recover_dquot_pass2(log, buffer_list, item,
						trans->r_lsn);
	case XFS_LI_ICREATE:
		return xlog_recover_do_icreate_pass2(log, buffer_list, item);
	case XFS_LI_QUOTAOFF:
		/* nothing to do in pass2 */
		return 0;
	default:
		xfs_warn(log->l_mp, "%s: invalid item type (%d)",
			__func__, ITEM_TYPE(item));
		ASSERT(0);
		return -EIO;
	}
}

STATIC int
xlog_recover_items_pass2(
	struct xlog                     *log,
	struct xlog_recover             *trans,
	struct list_head                *buffer_list,
	struct list_head                *item_list)
{
	struct xlog_recover_item	*item;
	int				error = 0;

	list_for_each_entry(item, item_list, ri_list) {
		error = xlog_recover_commit_pass2(log, trans,
					  buffer_list, item);
		if (error)
			return error;
	}

	return error;
}

/*
 * Perform the transaction.
 *
 * If the transaction modifies a buffer or inode, do it now.  Otherwise,
 * EFIs and EFDs get queued up by adding entries into the AIL for them.
 */
STATIC int
xlog_recover_commit_trans(
	struct xlog		*log,
	struct xlog_recover	*trans,
	int			pass,
	struct list_head	*buffer_list)
{
	int				error = 0;
	int				items_queued = 0;
	struct xlog_recover_item	*item;
	struct xlog_recover_item	*next;
	LIST_HEAD			(ra_list);
	LIST_HEAD			(done_list);

	#define XLOG_RECOVER_COMMIT_QUEUE_MAX 100

	hlist_del_init(&trans->r_list);

	error = xlog_recover_reorder_trans(log, trans, pass);
	if (error)
		return error;

	list_for_each_entry_safe(item, next, &trans->r_itemq, ri_list) {
		switch (pass) {
		case XLOG_RECOVER_PASS1:
			error = xlog_recover_commit_pass1(log, trans, item);
			break;
		case XLOG_RECOVER_PASS2:
			xlog_recover_ra_pass2(log, item);
			list_move_tail(&item->ri_list, &ra_list);
			items_queued++;
			if (items_queued >= XLOG_RECOVER_COMMIT_QUEUE_MAX) {
				error = xlog_recover_items_pass2(log, trans,
						buffer_list, &ra_list);
				list_splice_tail_init(&ra_list, &done_list);
				items_queued = 0;
			}

			break;
		default:
			ASSERT(0);
		}

		if (error)
			goto out;
	}

out:
	if (!list_empty(&ra_list)) {
		if (!error)
			error = xlog_recover_items_pass2(log, trans,
					buffer_list, &ra_list);
		list_splice_tail_init(&ra_list, &done_list);
	}

	if (!list_empty(&done_list))
		list_splice_init(&done_list, &trans->r_itemq);

	return error;
}

STATIC void
xlog_recover_add_item(
	struct list_head	*head)
{
	xlog_recover_item_t	*item;

	item = kmem_zalloc(sizeof(xlog_recover_item_t), KM_SLEEP);
	INIT_LIST_HEAD(&item->ri_list);
	list_add_tail(&item->ri_list, head);
}

STATIC int
xlog_recover_add_to_cont_trans(
	struct xlog		*log,
	struct xlog_recover	*trans,
	char			*dp,
	int			len)
{
	xlog_recover_item_t	*item;
	char			*ptr, *old_ptr;
	int			old_len;

	/*
	 * If the transaction is empty, the header was split across this and the
	 * previous record. Copy the rest of the header.
	 */
	if (list_empty(&trans->r_itemq)) {
		ASSERT(len <= sizeof(struct xfs_trans_header));
		if (len > sizeof(struct xfs_trans_header)) {
			xfs_warn(log->l_mp, "%s: bad header length", __func__);
			return -EIO;
		}

		xlog_recover_add_item(&trans->r_itemq);
		ptr = (char *)&trans->r_theader +
				sizeof(struct xfs_trans_header) - len;
		memcpy(ptr, dp, len);
		return 0;
	}

	/* take the tail entry */
	item = list_entry(trans->r_itemq.prev, xlog_recover_item_t, ri_list);

	old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
	old_len = item->ri_buf[item->ri_cnt-1].i_len;

	ptr = kmem_realloc(old_ptr, len + old_len, KM_SLEEP);
	memcpy(&ptr[old_len], dp, len);
	item->ri_buf[item->ri_cnt-1].i_len += len;
	item->ri_buf[item->ri_cnt-1].i_addr = ptr;
	trace_xfs_log_recover_item_add_cont(log, trans, item, 0);
	return 0;
}

/*
 * The next region to add is the start of a new region.  It could be
 * a whole region or it could be the first part of a new region.  Because
 * of this, the assumption here is that the type and size fields of all
 * format structures fit into the first 32 bits of the structure.
 *
 * This works because all regions must be 32 bit aligned.  Therefore, we
 * either have both fields or we have neither field.  In the case we have
 * neither field, the data part of the region is zero length.  We only have
 * a log_op_header and can throw away the header since a new one will appear
 * later.  If we have at least 4 bytes, then we can determine how many regions
 * will appear in the current log item.
 */
STATIC int
xlog_recover_add_to_trans(
	struct xlog		*log,
	struct xlog_recover	*trans,
	char			*dp,
	int			len)
{
	struct xfs_inode_log_format	*in_f;			/* any will do */
	xlog_recover_item_t	*item;
	char			*ptr;

	if (!len)
		return 0;
	if (list_empty(&trans->r_itemq)) {
		/* we need to catch log corruptions here */
		if (*(uint *)dp != XFS_TRANS_HEADER_MAGIC) {
			xfs_warn(log->l_mp, "%s: bad header magic number",
				__func__);
			ASSERT(0);
			return -EIO;
		}

		if (len > sizeof(struct xfs_trans_header)) {
			xfs_warn(log->l_mp, "%s: bad header length", __func__);
			ASSERT(0);
			return -EIO;
		}

		/*
		 * The transaction header can be arbitrarily split across op
		 * records. If we don't have the whole thing here, copy what we
		 * do have and handle the rest in the next record.
		 */
		if (len == sizeof(struct xfs_trans_header))
			xlog_recover_add_item(&trans->r_itemq);
		memcpy(&trans->r_theader, dp, len);
		return 0;
	}

	ptr = kmem_alloc(len, KM_SLEEP);
	memcpy(ptr, dp, len);
	in_f = (struct xfs_inode_log_format *)ptr;

	/* take the tail entry */
	item = list_entry(trans->r_itemq.prev, xlog_recover_item_t, ri_list);
	if (item->ri_total != 0 &&
	     item->ri_total == item->ri_cnt) {
		/* tail item is in use, get a new one */
		xlog_recover_add_item(&trans->r_itemq);
		item = list_entry(trans->r_itemq.prev,
					xlog_recover_item_t, ri_list);
	}

	if (item->ri_total == 0) {		/* first region to be added */
		if (in_f->ilf_size == 0 ||
		    in_f->ilf_size > XLOG_MAX_REGIONS_IN_ITEM) {
			xfs_warn(log->l_mp,
		"bad number of regions (%d) in inode log format",
				  in_f->ilf_size);
			ASSERT(0);
			kmem_free(ptr);
			return -EIO;
		}

		item->ri_total = in_f->ilf_size;
		item->ri_buf =
			kmem_zalloc(item->ri_total * sizeof(xfs_log_iovec_t),
				    KM_SLEEP);
	}
	ASSERT(item->ri_total > item->ri_cnt);
	/* Description region is ri_buf[0] */
	item->ri_buf[item->ri_cnt].i_addr = ptr;
	item->ri_buf[item->ri_cnt].i_len  = len;
	item->ri_cnt++;
	trace_xfs_log_recover_item_add(log, trans, item, 0);
	return 0;
}

/*
 * Free up any resources allocated by the transaction
 *
 * Remember that EFIs, EFDs, and IUNLINKs are handled later.
 */
STATIC void
xlog_recover_free_trans(
	struct xlog_recover	*trans)
{
	xlog_recover_item_t	*item, *n;
	int			i;

	hlist_del_init(&trans->r_list);

	list_for_each_entry_safe(item, n, &trans->r_itemq, ri_list) {
		/* Free the regions in the item. */
		list_del(&item->ri_list);
		for (i = 0; i < item->ri_cnt; i++)
			kmem_free(item->ri_buf[i].i_addr);
		/* Free the item itself */
		kmem_free(item->ri_buf);
		kmem_free(item);
	}
	/* Free the transaction recover structure */
	kmem_free(trans);
}

/*
 * On error or completion, trans is freed.
 */
STATIC int
xlog_recovery_process_trans(
	struct xlog		*log,
	struct xlog_recover	*trans,
	char			*dp,
	unsigned int		len,
	unsigned int		flags,
	int			pass,
	struct list_head	*buffer_list)
{
	int			error = 0;
	bool			freeit = false;

	/* mask off ophdr transaction container flags */
	flags &= ~XLOG_END_TRANS;
	if (flags & XLOG_WAS_CONT_TRANS)
		flags &= ~XLOG_CONTINUE_TRANS;

	/*
	 * Callees must not free the trans structure. We'll decide if we need to
	 * free it or not based on the operation being done and it's result.
	 */
	switch (flags) {
	/* expected flag values */
	case 0:
	case XLOG_CONTINUE_TRANS:
		error = xlog_recover_add_to_trans(log, trans, dp, len);
		break;
	case XLOG_WAS_CONT_TRANS:
		error = xlog_recover_add_to_cont_trans(log, trans, dp, len);
		break;
	case XLOG_COMMIT_TRANS:
		error = xlog_recover_commit_trans(log, trans, pass,
						  buffer_list);
		/* success or fail, we are now done with this transaction. */
		freeit = true;
		break;

	/* unexpected flag values */
	case XLOG_UNMOUNT_TRANS:
		/* just skip trans */
		xfs_warn(log->l_mp, "%s: Unmount LR", __func__);
		freeit = true;
		break;
	case XLOG_START_TRANS:
	default:
		xfs_warn(log->l_mp, "%s: bad flag 0x%x", __func__, flags);
		ASSERT(0);
		error = -EIO;
		break;
	}
	if (error || freeit)
		xlog_recover_free_trans(trans);
	return error;
}

/*
 * Lookup the transaction recovery structure associated with the ID in the
 * current ophdr. If the transaction doesn't exist and the start flag is set in
 * the ophdr, then allocate a new transaction for future ID matches to find.
 * Either way, return what we found during the lookup - an existing transaction
 * or nothing.
 */
STATIC struct xlog_recover *
xlog_recover_ophdr_to_trans(
	struct hlist_head	rhash[],
	struct xlog_rec_header	*rhead,
	struct xlog_op_header	*ohead)
{
	struct xlog_recover	*trans;
	xlog_tid_t		tid;
	struct hlist_head	*rhp;

	tid = be32_to_cpu(ohead->oh_tid);
	rhp = &rhash[XLOG_RHASH(tid)];
	hlist_for_each_entry(trans, rhp, r_list) {
		if (trans->r_log_tid == tid)
			return trans;
	}

	/*
	 * skip over non-start transaction headers - we could be
	 * processing slack space before the next transaction starts
	 */
	if (!(ohead->oh_flags & XLOG_START_TRANS))
		return NULL;

	ASSERT(be32_to_cpu(ohead->oh_len) == 0);

	/*
	 * This is a new transaction so allocate a new recovery container to
	 * hold the recovery ops that will follow.
	 */
	trans = kmem_zalloc(sizeof(struct xlog_recover), KM_SLEEP);
	trans->r_log_tid = tid;
	trans->r_lsn = be64_to_cpu(rhead->h_lsn);
	INIT_LIST_HEAD(&trans->r_itemq);
	INIT_HLIST_NODE(&trans->r_list);
	hlist_add_head(&trans->r_list, rhp);

	/*
	 * Nothing more to do for this ophdr. Items to be added to this new
	 * transaction will be in subsequent ophdr containers.
	 */
	return NULL;
}

STATIC int
xlog_recover_process_ophdr(
	struct xlog		*log,
	struct hlist_head	rhash[],
	struct xlog_rec_header	*rhead,
	struct xlog_op_header	*ohead,
	char			*dp,
	char			*end,
	int			pass,
	struct list_head	*buffer_list)
{
	struct xlog_recover	*trans;
	unsigned int		len;
	int			error;

	/* Do we understand who wrote this op? */
	if (ohead->oh_clientid != XFS_TRANSACTION &&
	    ohead->oh_clientid != XFS_LOG) {
		xfs_warn(log->l_mp, "%s: bad clientid 0x%x",
			__func__, ohead->oh_clientid);
		ASSERT(0);
		return -EIO;
	}

	/*
	 * Check the ophdr contains all the data it is supposed to contain.
	 */
	len = be32_to_cpu(ohead->oh_len);
	if (dp + len > end) {
		xfs_warn(log->l_mp, "%s: bad length 0x%x", __func__, len);
		WARN_ON(1);
		return -EIO;
	}

	trans = xlog_recover_ophdr_to_trans(rhash, rhead, ohead);
	if (!trans) {
		/* nothing to do, so skip over this ophdr */
		return 0;
	}

	/*
	 * The recovered buffer queue is drained only once we know that all
	 * recovery items for the current LSN have been processed. This is
	 * required because:
	 *
	 * - Buffer write submission updates the metadata LSN of the buffer.
	 * - Log recovery skips items with a metadata LSN >= the current LSN of
	 *   the recovery item.
	 * - Separate recovery items against the same metadata buffer can share
	 *   a current LSN. I.e., consider that the LSN of a recovery item is
	 *   defined as the starting LSN of the first record in which its
	 *   transaction appears, that a record can hold multiple transactions,
	 *   and/or that a transaction can span multiple records.
	 *
	 * In other words, we are allowed to submit a buffer from log recovery
	 * once per current LSN. Otherwise, we may incorrectly skip recovery
	 * items and cause corruption.
	 *
	 * We don't know up front whether buffers are updated multiple times per
	 * LSN. Therefore, track the current LSN of each commit log record as it
	 * is processed and drain the queue when it changes. Use commit records
	 * because they are ordered correctly by the logging code.
	 */
	if (log->l_recovery_lsn != trans->r_lsn &&
	    ohead->oh_flags & XLOG_COMMIT_TRANS) {
		error = xfs_buf_delwri_submit(buffer_list);
		if (error)
			return error;
		log->l_recovery_lsn = trans->r_lsn;
	}

	return xlog_recovery_process_trans(log, trans, dp, len,
					   ohead->oh_flags, pass, buffer_list);
}

/*
 * There are two valid states of the r_state field.  0 indicates that the
 * transaction structure is in a normal state.  We have either seen the
 * start of the transaction or the last operation we added was not a partial
 * operation.  If the last operation we added to the transaction was a
 * partial operation, we need to mark r_state with XLOG_WAS_CONT_TRANS.
 *
 * NOTE: skip LRs with 0 data length.
 */
STATIC int
xlog_recover_process_data(
	struct xlog		*log,
	struct hlist_head	rhash[],
	struct xlog_rec_header	*rhead,
	char			*dp,
	int			pass,
	struct list_head	*buffer_list)
{
	struct xlog_op_header	*ohead;
	char			*end;
	int			num_logops;
	int			error;

	end = dp + be32_to_cpu(rhead->h_len);
	num_logops = be32_to_cpu(rhead->h_num_logops);

	/* check the log format matches our own - else we can't recover */
	if (xlog_header_check_recover(log->l_mp, rhead))
		return -EIO;

	trace_xfs_log_recover_record(log, rhead, pass);
	while ((dp < end) && num_logops) {

		ohead = (struct xlog_op_header *)dp;
		dp += sizeof(*ohead);
		ASSERT(dp <= end);

		/* errors will abort recovery */
		error = xlog_recover_process_ophdr(log, rhash, rhead, ohead,
						   dp, end, pass, buffer_list);
		if (error)
			return error;

		dp += be32_to_cpu(ohead->oh_len);
		num_logops--;
	}
	return 0;
}

/* Recover the EFI if necessary. */
STATIC int
xlog_recover_process_efi(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip)
{
	struct xfs_efi_log_item		*efip;
	int				error;

	/*
	 * Skip EFIs that we've already processed.
	 */
	efip = container_of(lip, struct xfs_efi_log_item, efi_item);
	if (test_bit(XFS_EFI_RECOVERED, &efip->efi_flags))
		return 0;

	spin_unlock(&ailp->ail_lock);
	error = xfs_efi_recover(mp, efip);
	spin_lock(&ailp->ail_lock);

	return error;
}

/* Release the EFI since we're cancelling everything. */
STATIC void
xlog_recover_cancel_efi(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip)
{
	struct xfs_efi_log_item		*efip;

	efip = container_of(lip, struct xfs_efi_log_item, efi_item);

	spin_unlock(&ailp->ail_lock);
	xfs_efi_release(efip);
	spin_lock(&ailp->ail_lock);
}

/* Recover the RUI if necessary. */
STATIC int
xlog_recover_process_rui(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip)
{
	struct xfs_rui_log_item		*ruip;
	int				error;

	/*
	 * Skip RUIs that we've already processed.
	 */
	ruip = container_of(lip, struct xfs_rui_log_item, rui_item);
	if (test_bit(XFS_RUI_RECOVERED, &ruip->rui_flags))
		return 0;

	spin_unlock(&ailp->ail_lock);
	error = xfs_rui_recover(mp, ruip);
	spin_lock(&ailp->ail_lock);

	return error;
}

/* Release the RUI since we're cancelling everything. */
STATIC void
xlog_recover_cancel_rui(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip)
{
	struct xfs_rui_log_item		*ruip;

	ruip = container_of(lip, struct xfs_rui_log_item, rui_item);

	spin_unlock(&ailp->ail_lock);
	xfs_rui_release(ruip);
	spin_lock(&ailp->ail_lock);
}

/* Recover the CUI if necessary. */
STATIC int
xlog_recover_process_cui(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip,
	struct xfs_defer_ops		*dfops)
{
	struct xfs_cui_log_item		*cuip;
	int				error;

	/*
	 * Skip CUIs that we've already processed.
	 */
	cuip = container_of(lip, struct xfs_cui_log_item, cui_item);
	if (test_bit(XFS_CUI_RECOVERED, &cuip->cui_flags))
		return 0;

	spin_unlock(&ailp->ail_lock);
	error = xfs_cui_recover(mp, cuip, dfops);
	spin_lock(&ailp->ail_lock);

	return error;
}

/* Release the CUI since we're cancelling everything. */
STATIC void
xlog_recover_cancel_cui(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip)
{
	struct xfs_cui_log_item		*cuip;

	cuip = container_of(lip, struct xfs_cui_log_item, cui_item);

	spin_unlock(&ailp->ail_lock);
	xfs_cui_release(cuip);
	spin_lock(&ailp->ail_lock);
}

/* Recover the BUI if necessary. */
STATIC int
xlog_recover_process_bui(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip,
	struct xfs_defer_ops		*dfops)
{
	struct xfs_bui_log_item		*buip;
	int				error;

	/*
	 * Skip BUIs that we've already processed.
	 */
	buip = container_of(lip, struct xfs_bui_log_item, bui_item);
	if (test_bit(XFS_BUI_RECOVERED, &buip->bui_flags))
		return 0;

	spin_unlock(&ailp->ail_lock);
	error = xfs_bui_recover(mp, buip, dfops);
	spin_lock(&ailp->ail_lock);

	return error;
}

/* Release the BUI since we're cancelling everything. */
STATIC void
xlog_recover_cancel_bui(
	struct xfs_mount		*mp,
	struct xfs_ail			*ailp,
	struct xfs_log_item		*lip)
{
	struct xfs_bui_log_item		*buip;

	buip = container_of(lip, struct xfs_bui_log_item, bui_item);

	spin_unlock(&ailp->ail_lock);
	xfs_bui_release(buip);
	spin_lock(&ailp->ail_lock);
}

/* Is this log item a deferred action intent? */
static inline bool xlog_item_is_intent(struct xfs_log_item *lip)
{
	switch (lip->li_type) {
	case XFS_LI_EFI:
	case XFS_LI_RUI:
	case XFS_LI_CUI:
	case XFS_LI_BUI:
		return true;
	default:
		return false;
	}
}

/* Take all the collected deferred ops and finish them in order. */
static int
xlog_finish_defer_ops(
	struct xfs_mount	*mp,
	struct xfs_defer_ops	*dfops)
{
	struct xfs_trans	*tp;
	int64_t			freeblks;
	uint			resblks;
	int			error;

	/*
	 * We're finishing the defer_ops that accumulated as a result of
	 * recovering unfinished intent items during log recovery.  We
	 * reserve an itruncate transaction because it is the largest
	 * permanent transaction type.  Since we're the only user of the fs
	 * right now, take 93% (15/16) of the available free blocks.  Use
	 * weird math to avoid a 64-bit division.
	 */
	freeblks = percpu_counter_sum(&mp->m_fdblocks);
	if (freeblks <= 0)
		return -ENOSPC;
	resblks = min_t(int64_t, UINT_MAX, freeblks);
	resblks = (resblks * 15) >> 4;
	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks,
			0, XFS_TRANS_RESERVE, &tp);
	if (error)
		return error;

	error = xfs_defer_finish(&tp, dfops);
	if (error)
		goto out_cancel;

	return xfs_trans_commit(tp);

out_cancel:
	xfs_trans_cancel(tp);
	return error;
}

/*
 * When this is called, all of the log intent items which did not have
 * corresponding log done items should be in the AIL.  What we do now
 * is update the data structures associated with each one.
 *
 * Since we process the log intent items in normal transactions, they
 * will be removed at some point after the commit.  This prevents us
 * from just walking down the list processing each one.  We'll use a
 * flag in the intent item to skip those that we've already processed
 * and use the AIL iteration mechanism's generation count to try to
 * speed this up at least a bit.
 *
 * When we start, we know that the intents are the only things in the
 * AIL.  As we process them, however, other items are added to the
 * AIL.
 */
STATIC int
xlog_recover_process_intents(
	struct xlog		*log)
{
	struct xfs_defer_ops	dfops;
	struct xfs_ail_cursor	cur;
	struct xfs_log_item	*lip;
	struct xfs_ail		*ailp;
	xfs_fsblock_t		firstfsb;
	int			error = 0;
#if defined(DEBUG) || defined(XFS_WARN)
	xfs_lsn_t		last_lsn;
#endif

	ailp = log->l_ailp;
	spin_lock(&ailp->ail_lock);
	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
#if defined(DEBUG) || defined(XFS_WARN)
	last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block);
#endif
	xfs_defer_init(&dfops, &firstfsb);
	while (lip != NULL) {
		/*
		 * We're done when we see something other than an intent.
		 * There should be no intents left in the AIL now.
		 */
		if (!xlog_item_is_intent(lip)) {
#ifdef DEBUG
			for (; lip; lip = xfs_trans_ail_cursor_next(ailp, &cur))
				ASSERT(!xlog_item_is_intent(lip));
#endif
			break;
		}

		/*
		 * We should never see a redo item with a LSN higher than
		 * the last transaction we found in the log at the start
		 * of recovery.
		 */
		ASSERT(XFS_LSN_CMP(last_lsn, lip->li_lsn) >= 0);

		/*
		 * NOTE: If your intent processing routine can create more
		 * deferred ops, you /must/ attach them to the dfops in this
		 * routine or else those subsequent intents will get
		 * replayed in the wrong order!
		 */
		switch (lip->li_type) {
		case XFS_LI_EFI:
			error = xlog_recover_process_efi(log->l_mp, ailp, lip);
			break;
		case XFS_LI_RUI:
			error = xlog_recover_process_rui(log->l_mp, ailp, lip);
			break;
		case XFS_LI_CUI:
			error = xlog_recover_process_cui(log->l_mp, ailp, lip,
					&dfops);
			break;
		case XFS_LI_BUI:
			error = xlog_recover_process_bui(log->l_mp, ailp, lip,
					&dfops);
			break;
		}
		if (error)
			goto out;
		lip = xfs_trans_ail_cursor_next(ailp, &cur);
	}
out:
	xfs_trans_ail_cursor_done(&cur);
	spin_unlock(&ailp->ail_lock);
	if (error)
		xfs_defer_cancel(&dfops);
	else
		error = xlog_finish_defer_ops(log->l_mp, &dfops);

	return error;
}

/*
 * A cancel occurs when the mount has failed and we're bailing out.
 * Release all pending log intent items so they don't pin the AIL.
 */
STATIC int
xlog_recover_cancel_intents(
	struct xlog		*log)
{
	struct xfs_log_item	*lip;
	int			error = 0;
	struct xfs_ail_cursor	cur;
	struct xfs_ail		*ailp;

	ailp = log->l_ailp;
	spin_lock(&ailp->ail_lock);
	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
	while (lip != NULL) {
		/*
		 * We're done when we see something other than an intent.
		 * There should be no intents left in the AIL now.
		 */
		if (!xlog_item_is_intent(lip)) {
#ifdef DEBUG
			for (; lip; lip = xfs_trans_ail_cursor_next(ailp, &cur))
				ASSERT(!xlog_item_is_intent(lip));
#endif
			break;
		}

		switch (lip->li_type) {
		case XFS_LI_EFI:
			xlog_recover_cancel_efi(log->l_mp, ailp, lip);
			break;
		case XFS_LI_RUI:
			xlog_recover_cancel_rui(log->l_mp, ailp, lip);
			break;
		case XFS_LI_CUI:
			xlog_recover_cancel_cui(log->l_mp, ailp, lip);
			break;
		case XFS_LI_BUI:
			xlog_recover_cancel_bui(log->l_mp, ailp, lip);
			break;
		}

		lip = xfs_trans_ail_cursor_next(ailp, &cur);
	}

	xfs_trans_ail_cursor_done(&cur);
	spin_unlock(&ailp->ail_lock);
	return error;
}

/*
 * This routine performs a transaction to null out a bad inode pointer
 * in an agi unlinked inode hash bucket.
 */
STATIC void
xlog_recover_clear_agi_bucket(
	xfs_mount_t	*mp,
	xfs_agnumber_t	agno,
	int		bucket)
{
	xfs_trans_t	*tp;
	xfs_agi_t	*agi;
	xfs_buf_t	*agibp;
	int		offset;
	int		error;

	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_clearagi, 0, 0, 0, &tp);
	if (error)
		goto out_error;

	error = xfs_read_agi(mp, tp, agno, &agibp);
	if (error)
		goto out_abort;

	agi = XFS_BUF_TO_AGI(agibp);
	agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
	offset = offsetof(xfs_agi_t, agi_unlinked) +
		 (sizeof(xfs_agino_t) * bucket);
	xfs_trans_log_buf(tp, agibp, offset,
			  (offset + sizeof(xfs_agino_t) - 1));

	error = xfs_trans_commit(tp);
	if (error)
		goto out_error;
	return;

out_abort:
	xfs_trans_cancel(tp);
out_error:
	xfs_warn(mp, "%s: failed to clear agi %d. Continuing.", __func__, agno);
	return;
}

STATIC xfs_agino_t
xlog_recover_process_one_iunlink(
	struct xfs_mount		*mp,
	xfs_agnumber_t			agno,
	xfs_agino_t			agino,
	int				bucket)
{
	struct xfs_buf			*ibp;
	struct xfs_dinode		*dip;
	struct xfs_inode		*ip;
	xfs_ino_t			ino;
	int				error;

	ino = XFS_AGINO_TO_INO(mp, agno, agino);
	error = xfs_iget(mp, NULL, ino, 0, 0, &ip);
	if (error)
		goto fail;

	/*
	 * Get the on disk inode to find the next inode in the bucket.
	 */
	error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &ibp, 0, 0);
	if (error)
		goto fail_iput;

	xfs_iflags_clear(ip, XFS_IRECOVERY);
	ASSERT(VFS_I(ip)->i_nlink == 0);
	ASSERT(VFS_I(ip)->i_mode != 0);

	/* setup for the next pass */
	agino = be32_to_cpu(dip->di_next_unlinked);
	xfs_buf_relse(ibp);

	/*
	 * Prevent any DMAPI event from being sent when the reference on
	 * the inode is dropped.
	 */
	ip->i_d.di_dmevmask = 0;

	IRELE(ip);
	return agino;

 fail_iput:
	IRELE(ip);
 fail:
	/*
	 * We can't read in the inode this bucket points to, or this inode
	 * is messed up.  Just ditch this bucket of inodes.  We will lose
	 * some inodes and space, but at least we won't hang.
	 *
	 * Call xlog_recover_clear_agi_bucket() to perform a transaction to
	 * clear the inode pointer in the bucket.
	 */
	xlog_recover_clear_agi_bucket(mp, agno, bucket);
	return NULLAGINO;
}

/*
 * xlog_iunlink_recover
 *
 * This is called during recovery to process any inodes which
 * we unlinked but not freed when the system crashed.  These
 * inodes will be on the lists in the AGI blocks.  What we do
 * here is scan all the AGIs and fully truncate and free any
 * inodes found on the lists.  Each inode is removed from the
 * lists when it has been fully truncated and is freed.  The
 * freeing of the inode and its removal from the list must be
 * atomic.
 */
STATIC void
xlog_recover_process_iunlinks(
	struct xlog	*log)
{
	xfs_mount_t	*mp;
	xfs_agnumber_t	agno;
	xfs_agi_t	*agi;
	xfs_buf_t	*agibp;
	xfs_agino_t	agino;
	int		bucket;
	int		error;

	mp = log->l_mp;

	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
		/*
		 * Find the agi for this ag.
		 */
		error = xfs_read_agi(mp, NULL, agno, &agibp);
		if (error) {
			/*
			 * AGI is b0rked. Don't process it.
			 *
			 * We should probably mark the filesystem as corrupt
			 * after we've recovered all the ag's we can....
			 */
			continue;
		}
		/*
		 * Unlock the buffer so that it can be acquired in the normal
		 * course of the transaction to truncate and free each inode.
		 * Because we are not racing with anyone else here for the AGI
		 * buffer, we don't even need to hold it locked to read the
		 * initial unlinked bucket entries out of the buffer. We keep
		 * buffer reference though, so that it stays pinned in memory
		 * while we need the buffer.
		 */
		agi = XFS_BUF_TO_AGI(agibp);
		xfs_buf_unlock(agibp);

		for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
			agino = be32_to_cpu(agi->agi_unlinked[bucket]);
			while (agino != NULLAGINO) {
				agino = xlog_recover_process_one_iunlink(mp,
							agno, agino, bucket);
			}
		}
		xfs_buf_rele(agibp);
	}
}

STATIC int
xlog_unpack_data(
	struct xlog_rec_header	*rhead,
	char			*dp,
	struct xlog		*log)
{
	int			i, j, k;

	for (i = 0; i < BTOBB(be32_to_cpu(rhead->h_len)) &&
		  i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
		*(__be32 *)dp = *(__be32 *)&rhead->h_cycle_data[i];
		dp += BBSIZE;
	}

	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
		xlog_in_core_2_t *xhdr = (xlog_in_core_2_t *)rhead;
		for ( ; i < BTOBB(be32_to_cpu(rhead->h_len)); i++) {
			j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
			k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
			*(__be32 *)dp = xhdr[j].hic_xheader.xh_cycle_data[k];
			dp += BBSIZE;
		}
	}

	return 0;
}

/*
 * CRC check, unpack and process a log record.
 */
STATIC int
xlog_recover_process(
	struct xlog		*log,
	struct hlist_head	rhash[],
	struct xlog_rec_header	*rhead,
	char			*dp,
	int			pass,
	struct list_head	*buffer_list)
{
	int			error;
	__le32			old_crc = rhead->h_crc;
	__le32			crc;


	crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));

	/*
	 * Nothing else to do if this is a CRC verification pass. Just return
	 * if this a record with a non-zero crc. Unfortunately, mkfs always
	 * sets old_crc to 0 so we must consider this valid even on v5 supers.
	 * Otherwise, return EFSBADCRC on failure so the callers up the stack
	 * know precisely what failed.
	 */
	if (pass == XLOG_RECOVER_CRCPASS) {
		if (old_crc && crc != old_crc)
			return -EFSBADCRC;
		return 0;
	}

	/*
	 * We're in the normal recovery path. Issue a warning if and only if the
	 * CRC in the header is non-zero. This is an advisory warning and the
	 * zero CRC check prevents warnings from being emitted when upgrading
	 * the kernel from one that does not add CRCs by default.
	 */
	if (crc != old_crc) {
		if (old_crc || xfs_sb_version_hascrc(&log->l_mp->m_sb)) {
			xfs_alert(log->l_mp,
		"log record CRC mismatch: found 0x%x, expected 0x%x.",
					le32_to_cpu(old_crc),
					le32_to_cpu(crc));
			xfs_hex_dump(dp, 32);
		}

		/*
		 * If the filesystem is CRC enabled, this mismatch becomes a
		 * fatal log corruption failure.
		 */
		if (xfs_sb_version_hascrc(&log->l_mp->m_sb))
			return -EFSCORRUPTED;
	}

	error = xlog_unpack_data(rhead, dp, log);
	if (error)
		return error;

	return xlog_recover_process_data(log, rhash, rhead, dp, pass,
					 buffer_list);
}

STATIC int
xlog_valid_rec_header(
	struct xlog		*log,
	struct xlog_rec_header	*rhead,
	xfs_daddr_t		blkno)
{
	int			hlen;

	if (unlikely(rhead->h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM))) {
		XFS_ERROR_REPORT("xlog_valid_rec_header(1)",
				XFS_ERRLEVEL_LOW, log->l_mp);
		return -EFSCORRUPTED;
	}
	if (unlikely(
	    (!rhead->h_version ||
	    (be32_to_cpu(rhead->h_version) & (~XLOG_VERSION_OKBITS))))) {
		xfs_warn(log->l_mp, "%s: unrecognised log version (%d).",
			__func__, be32_to_cpu(rhead->h_version));
		return -EIO;
	}

	/* LR body must have data or it wouldn't have been written */
	hlen = be32_to_cpu(rhead->h_len);
	if (unlikely( hlen <= 0 || hlen > INT_MAX )) {
		XFS_ERROR_REPORT("xlog_valid_rec_header(2)",
				XFS_ERRLEVEL_LOW, log->l_mp);
		return -EFSCORRUPTED;
	}
	if (unlikely( blkno > log->l_logBBsize || blkno > INT_MAX )) {
		XFS_ERROR_REPORT("xlog_valid_rec_header(3)",
				XFS_ERRLEVEL_LOW, log->l_mp);
		return -EFSCORRUPTED;
	}
	return 0;
}

/*
 * Read the log from tail to head and process the log records found.
 * Handle the two cases where the tail and head are in the same cycle
 * and where the active portion of the log wraps around the end of
 * the physical log separately.  The pass parameter is passed through
 * to the routines called to process the data and is not looked at
 * here.
 */
STATIC int
xlog_do_recovery_pass(
	struct xlog		*log,
	xfs_daddr_t		head_blk,
	xfs_daddr_t		tail_blk,
	int			pass,
	xfs_daddr_t		*first_bad)	/* out: first bad log rec */
{
	xlog_rec_header_t	*rhead;
	xfs_daddr_t		blk_no, rblk_no;
	xfs_daddr_t		rhead_blk;
	char			*offset;
	xfs_buf_t		*hbp, *dbp;
	int			error = 0, h_size, h_len;
	int			error2 = 0;
	int			bblks, split_bblks;
	int			hblks, split_hblks, wrapped_hblks;
	int			i;
	struct hlist_head	rhash[XLOG_RHASH_SIZE];
	LIST_HEAD		(buffer_list);

	ASSERT(head_blk != tail_blk);
	blk_no = rhead_blk = tail_blk;

	for (i = 0; i < XLOG_RHASH_SIZE; i++)
		INIT_HLIST_HEAD(&rhash[i]);

	/*
	 * Read the header of the tail block and get the iclog buffer size from
	 * h_size.  Use this to tell how many sectors make up the log header.
	 */
	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
		/*
		 * When using variable length iclogs, read first sector of
		 * iclog header and extract the header size from it.  Get a
		 * new hbp that is the correct size.
		 */
		hbp = xlog_get_bp(log, 1);
		if (!hbp)
			return -ENOMEM;

		error = xlog_bread(log, tail_blk, 1, hbp, &offset);
		if (error)
			goto bread_err1;

		rhead = (xlog_rec_header_t *)offset;
		error = xlog_valid_rec_header(log, rhead, tail_blk);
		if (error)
			goto bread_err1;

		/*
		 * xfsprogs has a bug where record length is based on lsunit but
		 * h_size (iclog size) is hardcoded to 32k. Now that we
		 * unconditionally CRC verify the unmount record, this means the
		 * log buffer can be too small for the record and cause an
		 * overrun.
		 *
		 * Detect this condition here. Use lsunit for the buffer size as
		 * long as this looks like the mkfs case. Otherwise, return an
		 * error to avoid a buffer overrun.
		 */
		h_size = be32_to_cpu(rhead->h_size);
		h_len = be32_to_cpu(rhead->h_len);
		if (h_len > h_size) {
			if (h_len <= log->l_mp->m_logbsize &&
			    be32_to_cpu(rhead->h_num_logops) == 1) {
				xfs_warn(log->l_mp,
		"invalid iclog size (%d bytes), using lsunit (%d bytes)",
					 h_size, log->l_mp->m_logbsize);
				h_size = log->l_mp->m_logbsize;
			} else
				return -EFSCORRUPTED;
		}

		if ((be32_to_cpu(rhead->h_version) & XLOG_VERSION_2) &&
		    (h_size > XLOG_HEADER_CYCLE_SIZE)) {
			hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
			if (h_size % XLOG_HEADER_CYCLE_SIZE)
				hblks++;
			xlog_put_bp(hbp);
			hbp = xlog_get_bp(log, hblks);
		} else {
			hblks = 1;
		}
	} else {
		ASSERT(log->l_sectBBsize == 1);
		hblks = 1;
		hbp = xlog_get_bp(log, 1);
		h_size = XLOG_BIG_RECORD_BSIZE;
	}

	if (!hbp)
		return -ENOMEM;
	dbp = xlog_get_bp(log, BTOBB(h_size));
	if (!dbp) {
		xlog_put_bp(hbp);
		return -ENOMEM;
	}

	memset(rhash, 0, sizeof(rhash));
	if (tail_blk > head_blk) {
		/*
		 * Perform recovery around the end of the physical log.
		 * When the head is not on the same cycle number as the tail,
		 * we can't do a sequential recovery.
		 */
		while (blk_no < log->l_logBBsize) {
			/*
			 * Check for header wrapping around physical end-of-log
			 */
			offset = hbp->b_addr;
			split_hblks = 0;
			wrapped_hblks = 0;
			if (blk_no + hblks <= log->l_logBBsize) {
				/* Read header in one read */
				error = xlog_bread(log, blk_no, hblks, hbp,
						   &offset);
				if (error)
					goto bread_err2;
			} else {
				/* This LR is split across physical log end */
				if (blk_no != log->l_logBBsize) {
					/* some data before physical log end */
					ASSERT(blk_no <= INT_MAX);
					split_hblks = log->l_logBBsize - (int)blk_no;
					ASSERT(split_hblks > 0);
					error = xlog_bread(log, blk_no,
							   split_hblks, hbp,
							   &offset);
					if (error)
						goto bread_err2;
				}

				/*
				 * Note: this black magic still works with
				 * large sector sizes (non-512) only because:
				 * - we increased the buffer size originally
				 *   by 1 sector giving us enough extra space
				 *   for the second read;
				 * - the log start is guaranteed to be sector
				 *   aligned;
				 * - we read the log end (LR header start)
				 *   _first_, then the log start (LR header end)
				 *   - order is important.
				 */
				wrapped_hblks = hblks - split_hblks;
				error = xlog_bread_offset(log, 0,
						wrapped_hblks, hbp,
						offset + BBTOB(split_hblks));
				if (error)
					goto bread_err2;
			}
			rhead = (xlog_rec_header_t *)offset;
			error = xlog_valid_rec_header(log, rhead,
						split_hblks ? blk_no : 0);
			if (error)
				goto bread_err2;

			bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
			blk_no += hblks;

			/*
			 * Read the log record data in multiple reads if it
			 * wraps around the end of the log. Note that if the
			 * header already wrapped, blk_no could point past the
			 * end of the log. The record data is contiguous in
			 * that case.
			 */
			if (blk_no + bblks <= log->l_logBBsize ||
			    blk_no >= log->l_logBBsize) {
				/* mod blk_no in case the header wrapped and
				 * pushed it beyond the end of the log */
				rblk_no = do_mod(blk_no, log->l_logBBsize);
				error = xlog_bread(log, rblk_no, bblks, dbp,
						   &offset);
				if (error)
					goto bread_err2;
			} else {
				/* This log record is split across the
				 * physical end of log */
				offset = dbp->b_addr;
				split_bblks = 0;
				if (blk_no != log->l_logBBsize) {
					/* some data is before the physical
					 * end of log */
					ASSERT(!wrapped_hblks);
					ASSERT(blk_no <= INT_MAX);
					split_bblks =
						log->l_logBBsize - (int)blk_no;
					ASSERT(split_bblks > 0);
					error = xlog_bread(log, blk_no,
							split_bblks, dbp,
							&offset);
					if (error)
						goto bread_err2;
				}

				/*
				 * Note: this black magic still works with
				 * large sector sizes (non-512) only because:
				 * - we increased the buffer size originally
				 *   by 1 sector giving us enough extra space
				 *   for the second read;
				 * - the log start is guaranteed to be sector
				 *   aligned;
				 * - we read the log end (LR header start)
				 *   _first_, then the log start (LR header end)
				 *   - order is important.
				 */
				error = xlog_bread_offset(log, 0,
						bblks - split_bblks, dbp,
						offset + BBTOB(split_bblks));
				if (error)
					goto bread_err2;
			}

			error = xlog_recover_process(log, rhash, rhead, offset,
						     pass, &buffer_list);
			if (error)
				goto bread_err2;

			blk_no += bblks;
			rhead_blk = blk_no;
		}

		ASSERT(blk_no >= log->l_logBBsize);
		blk_no -= log->l_logBBsize;
		rhead_blk = blk_no;
	}

	/* read first part of physical log */
	while (blk_no < head_blk) {
		error = xlog_bread(log, blk_no, hblks, hbp, &offset);
		if (error)
			goto bread_err2;

		rhead = (xlog_rec_header_t *)offset;
		error = xlog_valid_rec_header(log, rhead, blk_no);
		if (error)
			goto bread_err2;

		/* blocks in data section */
		bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
		error = xlog_bread(log, blk_no+hblks, bblks, dbp,
				   &offset);
		if (error)
			goto bread_err2;

		error = xlog_recover_process(log, rhash, rhead, offset, pass,
					     &buffer_list);
		if (error)
			goto bread_err2;

		blk_no += bblks + hblks;
		rhead_blk = blk_no;
	}

 bread_err2:
	xlog_put_bp(dbp);
 bread_err1:
	xlog_put_bp(hbp);

	/*
	 * Submit buffers that have been added from the last record processed,
	 * regardless of error status.
	 */
	if (!list_empty(&buffer_list))
		error2 = xfs_buf_delwri_submit(&buffer_list);

	if (error && first_bad)
		*first_bad = rhead_blk;

	/*
	 * Transactions are freed at commit time but transactions without commit
	 * records on disk are never committed. Free any that may be left in the
	 * hash table.
	 */
	for (i = 0; i < XLOG_RHASH_SIZE; i++) {
		struct hlist_node	*tmp;
		struct xlog_recover	*trans;

		hlist_for_each_entry_safe(trans, tmp, &rhash[i], r_list)
			xlog_recover_free_trans(trans);
	}

	return error ? error : error2;
}

/*
 * Do the recovery of the log.  We actually do this in two phases.
 * The two passes are necessary in order to implement the function
 * of cancelling a record written into the log.  The first pass
 * determines those things which have been cancelled, and the
 * second pass replays log items normally except for those which
 * have been cancelled.  The handling of the replay and cancellations
 * takes place in the log item type specific routines.
 *
 * The table of items which have cancel records in the log is allocated
 * and freed at this level, since only here do we know when all of
 * the log recovery has been completed.
 */
STATIC int
xlog_do_log_recovery(
	struct xlog	*log,
	xfs_daddr_t	head_blk,
	xfs_daddr_t	tail_blk)
{
	int		error, i;

	ASSERT(head_blk != tail_blk);

	/*
	 * First do a pass to find all of the cancelled buf log items.
	 * Store them in the buf_cancel_table for use in the second pass.
	 */
	log->l_buf_cancel_table = kmem_zalloc(XLOG_BC_TABLE_SIZE *
						 sizeof(struct list_head),
						 KM_SLEEP);
	for (i = 0; i < XLOG_BC_TABLE_SIZE; i++)
		INIT_LIST_HEAD(&log->l_buf_cancel_table[i]);

	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
				      XLOG_RECOVER_PASS1, NULL);
	if (error != 0) {
		kmem_free(log->l_buf_cancel_table);
		log->l_buf_cancel_table = NULL;
		return error;
	}
	/*
	 * Then do a second pass to actually recover the items in the log.
	 * When it is complete free the table of buf cancel items.
	 */
	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
				      XLOG_RECOVER_PASS2, NULL);
#ifdef DEBUG
	if (!error) {
		int	i;

		for (i = 0; i < XLOG_BC_TABLE_SIZE; i++)
			ASSERT(list_empty(&log->l_buf_cancel_table[i]));
	}
#endif	/* DEBUG */

	kmem_free(log->l_buf_cancel_table);
	log->l_buf_cancel_table = NULL;

	return error;
}

/*
 * Do the actual recovery
 */
STATIC int
xlog_do_recover(
	struct xlog	*log,
	xfs_daddr_t	head_blk,
	xfs_daddr_t	tail_blk)
{
	struct xfs_mount *mp = log->l_mp;
	int		error;
	xfs_buf_t	*bp;
	xfs_sb_t	*sbp;

	trace_xfs_log_recover(log, head_blk, tail_blk);

	/*
	 * First replay the images in the log.
	 */
	error = xlog_do_log_recovery(log, head_blk, tail_blk);
	if (error)
		return error;

	/*
	 * If IO errors happened during recovery, bail out.
	 */
	if (XFS_FORCED_SHUTDOWN(mp)) {
		return -EIO;
	}

	/*
	 * We now update the tail_lsn since much of the recovery has completed
	 * and there may be space available to use.  If there were no extent
	 * or iunlinks, we can free up the entire log and set the tail_lsn to
	 * be the last_sync_lsn.  This was set in xlog_find_tail to be the
	 * lsn of the last known good LR on disk.  If there are extent frees
	 * or iunlinks they will have some entries in the AIL; so we look at
	 * the AIL to determine how to set the tail_lsn.
	 */
	xlog_assign_tail_lsn(mp);

	/*
	 * Now that we've finished replaying all buffer and inode
	 * updates, re-read in the superblock and reverify it.
	 */
	bp = xfs_getsb(mp, 0);
	bp->b_flags &= ~(XBF_DONE | XBF_ASYNC);
	ASSERT(!(bp->b_flags & XBF_WRITE));
	bp->b_flags |= XBF_READ;
	bp->b_ops = &xfs_sb_buf_ops;

	error = xfs_buf_submit_wait(bp);
	if (error) {
		if (!XFS_FORCED_SHUTDOWN(mp)) {
			xfs_buf_ioerror_alert(bp, __func__);
			ASSERT(0);
		}
		xfs_buf_relse(bp);
		return error;
	}

	/* Convert superblock from on-disk format */
	sbp = &mp->m_sb;
	xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp));
	xfs_buf_relse(bp);

	/* re-initialise in-core superblock and geometry structures */
	xfs_reinit_percpu_counters(mp);
	error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
	if (error) {
		xfs_warn(mp, "Failed post-recovery per-ag init: %d", error);
		return error;
	}
	mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);

	xlog_recover_check_summary(log);

	/* Normal transactions can now occur */
	log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
	return 0;
}

/*
 * Perform recovery and re-initialize some log variables in xlog_find_tail.
 *
 * Return error or zero.
 */
int
xlog_recover(
	struct xlog	*log)
{
	xfs_daddr_t	head_blk, tail_blk;
	int		error;

	/* find the tail of the log */
	error = xlog_find_tail(log, &head_blk, &tail_blk);
	if (error)
		return error;

	/*
	 * The superblock was read before the log was available and thus the LSN
	 * could not be verified. Check the superblock LSN against the current
	 * LSN now that it's known.
	 */
	if (xfs_sb_version_hascrc(&log->l_mp->m_sb) &&
	    !xfs_log_check_lsn(log->l_mp, log->l_mp->m_sb.sb_lsn))
		return -EINVAL;

	if (tail_blk != head_blk) {
		/* There used to be a comment here:
		 *
		 * disallow recovery on read-only mounts.  note -- mount
		 * checks for ENOSPC and turns it into an intelligent
		 * error message.
		 * ...but this is no longer true.  Now, unless you specify
		 * NORECOVERY (in which case this function would never be
		 * called), we just go ahead and recover.  We do this all
		 * under the vfs layer, so we can get away with it unless
		 * the device itself is read-only, in which case we fail.
		 */
		if ((error = xfs_dev_is_read_only(log->l_mp, "recovery"))) {
			return error;
		}

		/*
		 * Version 5 superblock log feature mask validation. We know the
		 * log is dirty so check if there are any unknown log features
		 * in what we need to recover. If there are unknown features
		 * (e.g. unsupported transactions, then simply reject the
		 * attempt at recovery before touching anything.
		 */
		if (XFS_SB_VERSION_NUM(&log->l_mp->m_sb) == XFS_SB_VERSION_5 &&
		    xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
			xfs_warn(log->l_mp,
"Superblock has unknown incompatible log features (0x%x) enabled.",
				(log->l_mp->m_sb.sb_features_log_incompat &
					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
			xfs_warn(log->l_mp,
"The log can not be fully and/or safely recovered by this kernel.");
			xfs_warn(log->l_mp,
"Please recover the log on a kernel that supports the unknown features.");
			return -EINVAL;
		}

		/*
		 * Delay log recovery if the debug hook is set. This is debug
		 * instrumention to coordinate simulation of I/O failures with
		 * log recovery.
		 */
		if (xfs_globals.log_recovery_delay) {
			xfs_notice(log->l_mp,
				"Delaying log recovery for %d seconds.",
				xfs_globals.log_recovery_delay);
			msleep(xfs_globals.log_recovery_delay * 1000);
		}

		xfs_notice(log->l_mp, "Starting recovery (logdev: %s)",
				log->l_mp->m_logname ? log->l_mp->m_logname
						     : "internal");

		error = xlog_do_recover(log, head_blk, tail_blk);
		log->l_flags |= XLOG_RECOVERY_NEEDED;
	}
	return error;
}

/*
 * In the first part of recovery we replay inodes and buffers and build
 * up the list of extent free items which need to be processed.  Here
 * we process the extent free items and clean up the on disk unlinked
 * inode lists.  This is separated from the first part of recovery so
 * that the root and real-time bitmap inodes can be read in from disk in
 * between the two stages.  This is necessary so that we can free space
 * in the real-time portion of the file system.
 */
int
xlog_recover_finish(
	struct xlog	*log)
{
	/*
	 * Now we're ready to do the transactions needed for the
	 * rest of recovery.  Start with completing all the extent
	 * free intent records and then process the unlinked inode
	 * lists.  At this point, we essentially run in normal mode
	 * except that we're still performing recovery actions
	 * rather than accepting new requests.
	 */
	if (log->l_flags & XLOG_RECOVERY_NEEDED) {
		int	error;
		error = xlog_recover_process_intents(log);
		if (error) {
			xfs_alert(log->l_mp, "Failed to recover intents");
			return error;
		}

		/*
		 * Sync the log to get all the intents out of the AIL.
		 * This isn't absolutely necessary, but it helps in
		 * case the unlink transactions would have problems
		 * pushing the intents out of the way.
		 */
		xfs_log_force(log->l_mp, XFS_LOG_SYNC);

		xlog_recover_process_iunlinks(log);

		xlog_recover_check_summary(log);

		xfs_notice(log->l_mp, "Ending recovery (logdev: %s)",
				log->l_mp->m_logname ? log->l_mp->m_logname
						     : "internal");
		log->l_flags &= ~XLOG_RECOVERY_NEEDED;
	} else {
		xfs_info(log->l_mp, "Ending clean mount");
	}
	return 0;
}

int
xlog_recover_cancel(
	struct xlog	*log)
{
	int		error = 0;

	if (log->l_flags & XLOG_RECOVERY_NEEDED)
		error = xlog_recover_cancel_intents(log);

	return error;
}

#if defined(DEBUG)
/*
 * Read all of the agf and agi counters and check that they
 * are consistent with the superblock counters.
 */
STATIC void
xlog_recover_check_summary(
	struct xlog	*log)
{
	xfs_mount_t	*mp;
	xfs_agf_t	*agfp;
	xfs_buf_t	*agfbp;
	xfs_buf_t	*agibp;
	xfs_agnumber_t	agno;
	uint64_t	freeblks;
	uint64_t	itotal;
	uint64_t	ifree;
	int		error;

	mp = log->l_mp;

	freeblks = 0LL;
	itotal = 0LL;
	ifree = 0LL;
	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
		error = xfs_read_agf(mp, NULL, agno, 0, &agfbp);
		if (error) {
			xfs_alert(mp, "%s agf read failed agno %d error %d",
						__func__, agno, error);
		} else {
			agfp = XFS_BUF_TO_AGF(agfbp);
			freeblks += be32_to_cpu(agfp->agf_freeblks) +
				    be32_to_cpu(agfp->agf_flcount);
			xfs_buf_relse(agfbp);
		}

		error = xfs_read_agi(mp, NULL, agno, &agibp);
		if (error) {
			xfs_alert(mp, "%s agi read failed agno %d error %d",
						__func__, agno, error);
		} else {
			struct xfs_agi	*agi = XFS_BUF_TO_AGI(agibp);

			itotal += be32_to_cpu(agi->agi_count);
			ifree += be32_to_cpu(agi->agi_freecount);
			xfs_buf_relse(agibp);
		}
	}
}
#endif /* DEBUG */