summaryrefslogtreecommitdiff
path: root/fs/btrfs/tree-log.c
blob: 0a1bde26896338d918de06d258f3dd752aadbdd1 (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
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/sched.h>
#include "ctree.h"
#include "transaction.h"
#include "disk-io.h"
#include "locking.h"
#include "print-tree.h"
#include "compat.h"
#include "tree-log.h"

/* magic values for the inode_only field in btrfs_log_inode:
 *
 * LOG_INODE_ALL means to log everything
 * LOG_INODE_EXISTS means to log just enough to recreate the inode
 * during log replay
 */
#define LOG_INODE_ALL 0
#define LOG_INODE_EXISTS 1

/*
 * directory trouble cases
 *
 * 1) on rename or unlink, if the inode being unlinked isn't in the fsync
 * log, we must force a full commit before doing an fsync of the directory
 * where the unlink was done.
 * ---> record transid of last unlink/rename per directory
 *
 * mkdir foo/some_dir
 * normal commit
 * rename foo/some_dir foo2/some_dir
 * mkdir foo/some_dir
 * fsync foo/some_dir/some_file
 *
 * The fsync above will unlink the original some_dir without recording
 * it in its new location (foo2).  After a crash, some_dir will be gone
 * unless the fsync of some_file forces a full commit
 *
 * 2) we must log any new names for any file or dir that is in the fsync
 * log. ---> check inode while renaming/linking.
 *
 * 2a) we must log any new names for any file or dir during rename
 * when the directory they are being removed from was logged.
 * ---> check inode and old parent dir during rename
 *
 *  2a is actually the more important variant.  With the extra logging
 *  a crash might unlink the old name without recreating the new one
 *
 * 3) after a crash, we must go through any directories with a link count
 * of zero and redo the rm -rf
 *
 * mkdir f1/foo
 * normal commit
 * rm -rf f1/foo
 * fsync(f1)
 *
 * The directory f1 was fully removed from the FS, but fsync was never
 * called on f1, only its parent dir.  After a crash the rm -rf must
 * be replayed.  This must be able to recurse down the entire
 * directory tree.  The inode link count fixup code takes care of the
 * ugly details.
 */

/*
 * stages for the tree walking.  The first
 * stage (0) is to only pin down the blocks we find
 * the second stage (1) is to make sure that all the inodes
 * we find in the log are created in the subvolume.
 *
 * The last stage is to deal with directories and links and extents
 * and all the other fun semantics
 */
#define LOG_WALK_PIN_ONLY 0
#define LOG_WALK_REPLAY_INODES 1
#define LOG_WALK_REPLAY_ALL 2

static int btrfs_log_inode(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root, struct inode *inode,
			     int inode_only);
static int link_to_fixup_dir(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root,
			     struct btrfs_path *path, u64 objectid);
static noinline int replay_dir_deletes(struct btrfs_trans_handle *trans,
				       struct btrfs_root *root,
				       struct btrfs_root *log,
				       struct btrfs_path *path,
				       u64 dirid, int del_all);

/*
 * tree logging is a special write ahead log used to make sure that
 * fsyncs and O_SYNCs can happen without doing full tree commits.
 *
 * Full tree commits are expensive because they require commonly
 * modified blocks to be recowed, creating many dirty pages in the
 * extent tree an 4x-6x higher write load than ext3.
 *
 * Instead of doing a tree commit on every fsync, we use the
 * key ranges and transaction ids to find items for a given file or directory
 * that have changed in this transaction.  Those items are copied into
 * a special tree (one per subvolume root), that tree is written to disk
 * and then the fsync is considered complete.
 *
 * After a crash, items are copied out of the log-tree back into the
 * subvolume tree.  Any file data extents found are recorded in the extent
 * allocation tree, and the log-tree freed.
 *
 * The log tree is read three times, once to pin down all the extents it is
 * using in ram and once, once to create all the inodes logged in the tree
 * and once to do all the other items.
 */

/*
 * start a sub transaction and setup the log tree
 * this increments the log tree writer count to make the people
 * syncing the tree wait for us to finish
 */
static int start_log_trans(struct btrfs_trans_handle *trans,
			   struct btrfs_root *root)
{
	int ret;

	mutex_lock(&root->log_mutex);
	if (root->log_root) {
		if (!root->log_start_pid) {
			root->log_start_pid = current->pid;
			root->log_multiple_pids = false;
		} else if (root->log_start_pid != current->pid) {
			root->log_multiple_pids = true;
		}

		root->log_batch++;
		atomic_inc(&root->log_writers);
		mutex_unlock(&root->log_mutex);
		return 0;
	}
	root->log_multiple_pids = false;
	root->log_start_pid = current->pid;
	mutex_lock(&root->fs_info->tree_log_mutex);
	if (!root->fs_info->log_root_tree) {
		ret = btrfs_init_log_root_tree(trans, root->fs_info);
		BUG_ON(ret);
	}
	if (!root->log_root) {
		ret = btrfs_add_log_tree(trans, root);
		BUG_ON(ret);
	}
	mutex_unlock(&root->fs_info->tree_log_mutex);
	root->log_batch++;
	atomic_inc(&root->log_writers);
	mutex_unlock(&root->log_mutex);
	return 0;
}

/*
 * returns 0 if there was a log transaction running and we were able
 * to join, or returns -ENOENT if there were not transactions
 * in progress
 */
static int join_running_log_trans(struct btrfs_root *root)
{
	int ret = -ENOENT;

	smp_mb();
	if (!root->log_root)
		return -ENOENT;

	mutex_lock(&root->log_mutex);
	if (root->log_root) {
		ret = 0;
		atomic_inc(&root->log_writers);
	}
	mutex_unlock(&root->log_mutex);
	return ret;
}

/*
 * This either makes the current running log transaction wait
 * until you call btrfs_end_log_trans() or it makes any future
 * log transactions wait until you call btrfs_end_log_trans()
 */
int btrfs_pin_log_trans(struct btrfs_root *root)
{
	int ret = -ENOENT;

	mutex_lock(&root->log_mutex);
	atomic_inc(&root->log_writers);
	mutex_unlock(&root->log_mutex);
	return ret;
}

/*
 * indicate we're done making changes to the log tree
 * and wake up anyone waiting to do a sync
 */
int btrfs_end_log_trans(struct btrfs_root *root)
{
	if (atomic_dec_and_test(&root->log_writers)) {
		smp_mb();
		if (waitqueue_active(&root->log_writer_wait))
			wake_up(&root->log_writer_wait);
	}
	return 0;
}


/*
 * the walk control struct is used to pass state down the chain when
 * processing the log tree.  The stage field tells us which part
 * of the log tree processing we are currently doing.  The others
 * are state fields used for that specific part
 */
struct walk_control {
	/* should we free the extent on disk when done?  This is used
	 * at transaction commit time while freeing a log tree
	 */
	int free;

	/* should we write out the extent buffer?  This is used
	 * while flushing the log tree to disk during a sync
	 */
	int write;

	/* should we wait for the extent buffer io to finish?  Also used
	 * while flushing the log tree to disk for a sync
	 */
	int wait;

	/* pin only walk, we record which extents on disk belong to the
	 * log trees
	 */
	int pin;

	/* what stage of the replay code we're currently in */
	int stage;

	/* the root we are currently replaying */
	struct btrfs_root *replay_dest;

	/* the trans handle for the current replay */
	struct btrfs_trans_handle *trans;

	/* the function that gets used to process blocks we find in the
	 * tree.  Note the extent_buffer might not be up to date when it is
	 * passed in, and it must be checked or read if you need the data
	 * inside it
	 */
	int (*process_func)(struct btrfs_root *log, struct extent_buffer *eb,
			    struct walk_control *wc, u64 gen);
};

/*
 * process_func used to pin down extents, write them or wait on them
 */
static int process_one_buffer(struct btrfs_root *log,
			      struct extent_buffer *eb,
			      struct walk_control *wc, u64 gen)
{
	if (wc->pin)
		btrfs_pin_extent(log->fs_info->extent_root,
				 eb->start, eb->len, 0);

	if (btrfs_buffer_uptodate(eb, gen)) {
		if (wc->write)
			btrfs_write_tree_block(eb);
		if (wc->wait)
			btrfs_wait_tree_block_writeback(eb);
	}
	return 0;
}

/*
 * Item overwrite used by replay and tree logging.  eb, slot and key all refer
 * to the src data we are copying out.
 *
 * root is the tree we are copying into, and path is a scratch
 * path for use in this function (it should be released on entry and
 * will be released on exit).
 *
 * If the key is already in the destination tree the existing item is
 * overwritten.  If the existing item isn't big enough, it is extended.
 * If it is too large, it is truncated.
 *
 * If the key isn't in the destination yet, a new item is inserted.
 */
static noinline int overwrite_item(struct btrfs_trans_handle *trans,
				   struct btrfs_root *root,
				   struct btrfs_path *path,
				   struct extent_buffer *eb, int slot,
				   struct btrfs_key *key)
{
	int ret;
	u32 item_size;
	u64 saved_i_size = 0;
	int save_old_i_size = 0;
	unsigned long src_ptr;
	unsigned long dst_ptr;
	int overwrite_root = 0;

	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID)
		overwrite_root = 1;

	item_size = btrfs_item_size_nr(eb, slot);
	src_ptr = btrfs_item_ptr_offset(eb, slot);

	/* look for the key in the destination tree */
	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
	if (ret == 0) {
		char *src_copy;
		char *dst_copy;
		u32 dst_size = btrfs_item_size_nr(path->nodes[0],
						  path->slots[0]);
		if (dst_size != item_size)
			goto insert;

		if (item_size == 0) {
			btrfs_release_path(root, path);
			return 0;
		}
		dst_copy = kmalloc(item_size, GFP_NOFS);
		src_copy = kmalloc(item_size, GFP_NOFS);

		read_extent_buffer(eb, src_copy, src_ptr, item_size);

		dst_ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
		read_extent_buffer(path->nodes[0], dst_copy, dst_ptr,
				   item_size);
		ret = memcmp(dst_copy, src_copy, item_size);

		kfree(dst_copy);
		kfree(src_copy);
		/*
		 * they have the same contents, just return, this saves
		 * us from cowing blocks in the destination tree and doing
		 * extra writes that may not have been done by a previous
		 * sync
		 */
		if (ret == 0) {
			btrfs_release_path(root, path);
			return 0;
		}

	}
insert:
	btrfs_release_path(root, path);
	/* try to insert the key into the destination tree */
	ret = btrfs_insert_empty_item(trans, root, path,
				      key, item_size);

	/* make sure any existing item is the correct size */
	if (ret == -EEXIST) {
		u32 found_size;
		found_size = btrfs_item_size_nr(path->nodes[0],
						path->slots[0]);
		if (found_size > item_size) {
			btrfs_truncate_item(trans, root, path, item_size, 1);
		} else if (found_size < item_size) {
			ret = btrfs_extend_item(trans, root, path,
						item_size - found_size);
			BUG_ON(ret);
		}
	} else if (ret) {
		BUG();
	}
	dst_ptr = btrfs_item_ptr_offset(path->nodes[0],
					path->slots[0]);

	/* don't overwrite an existing inode if the generation number
	 * was logged as zero.  This is done when the tree logging code
	 * is just logging an inode to make sure it exists after recovery.
	 *
	 * Also, don't overwrite i_size on directories during replay.
	 * log replay inserts and removes directory items based on the
	 * state of the tree found in the subvolume, and i_size is modified
	 * as it goes
	 */
	if (key->type == BTRFS_INODE_ITEM_KEY && ret == -EEXIST) {
		struct btrfs_inode_item *src_item;
		struct btrfs_inode_item *dst_item;

		src_item = (struct btrfs_inode_item *)src_ptr;
		dst_item = (struct btrfs_inode_item *)dst_ptr;

		if (btrfs_inode_generation(eb, src_item) == 0)
			goto no_copy;

		if (overwrite_root &&
		    S_ISDIR(btrfs_inode_mode(eb, src_item)) &&
		    S_ISDIR(btrfs_inode_mode(path->nodes[0], dst_item))) {
			save_old_i_size = 1;
			saved_i_size = btrfs_inode_size(path->nodes[0],
							dst_item);
		}
	}

	copy_extent_buffer(path->nodes[0], eb, dst_ptr,
			   src_ptr, item_size);

	if (save_old_i_size) {
		struct btrfs_inode_item *dst_item;
		dst_item = (struct btrfs_inode_item *)dst_ptr;
		btrfs_set_inode_size(path->nodes[0], dst_item, saved_i_size);
	}

	/* make sure the generation is filled in */
	if (key->type == BTRFS_INODE_ITEM_KEY) {
		struct btrfs_inode_item *dst_item;
		dst_item = (struct btrfs_inode_item *)dst_ptr;
		if (btrfs_inode_generation(path->nodes[0], dst_item) == 0) {
			btrfs_set_inode_generation(path->nodes[0], dst_item,
						   trans->transid);
		}
	}
no_copy:
	btrfs_mark_buffer_dirty(path->nodes[0]);
	btrfs_release_path(root, path);
	return 0;
}

/*
 * simple helper to read an inode off the disk from a given root
 * This can only be called for subvolume roots and not for the log
 */
static noinline struct inode *read_one_inode(struct btrfs_root *root,
					     u64 objectid)
{
	struct btrfs_key key;
	struct inode *inode;

	key.objectid = objectid;
	key.type = BTRFS_INODE_ITEM_KEY;
	key.offset = 0;
	inode = btrfs_iget(root->fs_info->sb, &key, root);
	if (IS_ERR(inode)) {
		inode = NULL;
	} else if (is_bad_inode(inode)) {
		iput(inode);
		inode = NULL;
	}
	return inode;
}

/* replays a single extent in 'eb' at 'slot' with 'key' into the
 * subvolume 'root'.  path is released on entry and should be released
 * on exit.
 *
 * extents in the log tree have not been allocated out of the extent
 * tree yet.  So, this completes the allocation, taking a reference
 * as required if the extent already exists or creating a new extent
 * if it isn't in the extent allocation tree yet.
 *
 * The extent is inserted into the file, dropping any existing extents
 * from the file that overlap the new one.
 */
static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
				      struct btrfs_root *root,
				      struct btrfs_path *path,
				      struct extent_buffer *eb, int slot,
				      struct btrfs_key *key)
{
	int found_type;
	u64 mask = root->sectorsize - 1;
	u64 extent_end;
	u64 alloc_hint;
	u64 start = key->offset;
	u64 saved_nbytes;
	struct btrfs_file_extent_item *item;
	struct inode *inode = NULL;
	unsigned long size;
	int ret = 0;

	item = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
	found_type = btrfs_file_extent_type(eb, item);

	if (found_type == BTRFS_FILE_EXTENT_REG ||
	    found_type == BTRFS_FILE_EXTENT_PREALLOC)
		extent_end = start + btrfs_file_extent_num_bytes(eb, item);
	else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
		size = btrfs_file_extent_inline_len(eb, item);
		extent_end = (start + size + mask) & ~mask;
	} else {
		ret = 0;
		goto out;
	}

	inode = read_one_inode(root, key->objectid);
	if (!inode) {
		ret = -EIO;
		goto out;
	}

	/*
	 * first check to see if we already have this extent in the
	 * file.  This must be done before the btrfs_drop_extents run
	 * so we don't try to drop this extent.
	 */
	ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
				       start, 0);

	if (ret == 0 &&
	    (found_type == BTRFS_FILE_EXTENT_REG ||
	     found_type == BTRFS_FILE_EXTENT_PREALLOC)) {
		struct btrfs_file_extent_item cmp1;
		struct btrfs_file_extent_item cmp2;
		struct btrfs_file_extent_item *existing;
		struct extent_buffer *leaf;

		leaf = path->nodes[0];
		existing = btrfs_item_ptr(leaf, path->slots[0],
					  struct btrfs_file_extent_item);

		read_extent_buffer(eb, &cmp1, (unsigned long)item,
				   sizeof(cmp1));
		read_extent_buffer(leaf, &cmp2, (unsigned long)existing,
				   sizeof(cmp2));

		/*
		 * we already have a pointer to this exact extent,
		 * we don't have to do anything
		 */
		if (memcmp(&cmp1, &cmp2, sizeof(cmp1)) == 0) {
			btrfs_release_path(root, path);
			goto out;
		}
	}
	btrfs_release_path(root, path);

	saved_nbytes = inode_get_bytes(inode);
	/* drop any overlapping extents */
	ret = btrfs_drop_extents(trans, root, inode,
			 start, extent_end, extent_end, start, &alloc_hint, 1);
	BUG_ON(ret);

	if (found_type == BTRFS_FILE_EXTENT_REG ||
	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
		u64 offset;
		unsigned long dest_offset;
		struct btrfs_key ins;

		ret = btrfs_insert_empty_item(trans, root, path, key,
					      sizeof(*item));
		BUG_ON(ret);
		dest_offset = btrfs_item_ptr_offset(path->nodes[0],
						    path->slots[0]);
		copy_extent_buffer(path->nodes[0], eb, dest_offset,
				(unsigned long)item,  sizeof(*item));

		ins.objectid = btrfs_file_extent_disk_bytenr(eb, item);
		ins.offset = btrfs_file_extent_disk_num_bytes(eb, item);
		ins.type = BTRFS_EXTENT_ITEM_KEY;
		offset = key->offset - btrfs_file_extent_offset(eb, item);

		if (ins.objectid > 0) {
			u64 csum_start;
			u64 csum_end;
			LIST_HEAD(ordered_sums);
			/*
			 * is this extent already allocated in the extent
			 * allocation tree?  If so, just add a reference
			 */
			ret = btrfs_lookup_extent(root, ins.objectid,
						ins.offset);
			if (ret == 0) {
				ret = btrfs_inc_extent_ref(trans, root,
						ins.objectid, ins.offset,
						0, root->root_key.objectid,
						key->objectid, offset);
			} else {
				/*
				 * insert the extent pointer in the extent
				 * allocation tree
				 */
				ret = btrfs_alloc_logged_file_extent(trans,
						root, root->root_key.objectid,
						key->objectid, offset, &ins);
				BUG_ON(ret);
			}
			btrfs_release_path(root, path);

			if (btrfs_file_extent_compression(eb, item)) {
				csum_start = ins.objectid;
				csum_end = csum_start + ins.offset;
			} else {
				csum_start = ins.objectid +
					btrfs_file_extent_offset(eb, item);
				csum_end = csum_start +
					btrfs_file_extent_num_bytes(eb, item);
			}

			ret = btrfs_lookup_csums_range(root->log_root,
						csum_start, csum_end - 1,
						&ordered_sums);
			BUG_ON(ret);
			while (!list_empty(&ordered_sums)) {
				struct btrfs_ordered_sum *sums;
				sums = list_entry(ordered_sums.next,
						struct btrfs_ordered_sum,
						list);
				ret = btrfs_csum_file_blocks(trans,
						root->fs_info->csum_root,
						sums);
				BUG_ON(ret);
				list_del(&sums->list);
				kfree(sums);
			}
		} else {
			btrfs_release_path(root, path);
		}
	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
		/* inline extents are easy, we just overwrite them */
		ret = overwrite_item(trans, root, path, eb, slot, key);
		BUG_ON(ret);
	}

	inode_set_bytes(inode, saved_nbytes);
	btrfs_update_inode(trans, root, inode);
out:
	if (inode)
		iput(inode);
	return ret;
}

/*
 * when cleaning up conflicts between the directory names in the
 * subvolume, directory names in the log and directory names in the
 * inode back references, we may have to unlink inodes from directories.
 *
 * This is a helper function to do the unlink of a specific directory
 * item
 */
static noinline int drop_one_dir_item(struct btrfs_trans_handle *trans,
				      struct btrfs_root *root,
				      struct btrfs_path *path,
				      struct inode *dir,
				      struct btrfs_dir_item *di)
{
	struct inode *inode;
	char *name;
	int name_len;
	struct extent_buffer *leaf;
	struct btrfs_key location;
	int ret;

	leaf = path->nodes[0];

	btrfs_dir_item_key_to_cpu(leaf, di, &location);
	name_len = btrfs_dir_name_len(leaf, di);
	name = kmalloc(name_len, GFP_NOFS);
	read_extent_buffer(leaf, name, (unsigned long)(di + 1), name_len);
	btrfs_release_path(root, path);

	inode = read_one_inode(root, location.objectid);
	BUG_ON(!inode);

	ret = link_to_fixup_dir(trans, root, path, location.objectid);
	BUG_ON(ret);

	ret = btrfs_unlink_inode(trans, root, dir, inode, name, name_len);
	BUG_ON(ret);
	kfree(name);

	iput(inode);
	return ret;
}

/*
 * helper function to see if a given name and sequence number found
 * in an inode back reference are already in a directory and correctly
 * point to this inode
 */
static noinline int inode_in_dir(struct btrfs_root *root,
				 struct btrfs_path *path,
				 u64 dirid, u64 objectid, u64 index,
				 const char *name, int name_len)
{
	struct btrfs_dir_item *di;
	struct btrfs_key location;
	int match = 0;

	di = btrfs_lookup_dir_index_item(NULL, root, path, dirid,
					 index, name, name_len, 0);
	if (di && !IS_ERR(di)) {
		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
		if (location.objectid != objectid)
			goto out;
	} else
		goto out;
	btrfs_release_path(root, path);

	di = btrfs_lookup_dir_item(NULL, root, path, dirid, name, name_len, 0);
	if (di && !IS_ERR(di)) {
		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
		if (location.objectid != objectid)
			goto out;
	} else
		goto out;
	match = 1;
out:
	btrfs_release_path(root, path);
	return match;
}

/*
 * helper function to check a log tree for a named back reference in
 * an inode.  This is used to decide if a back reference that is
 * found in the subvolume conflicts with what we find in the log.
 *
 * inode backreferences may have multiple refs in a single item,
 * during replay we process one reference at a time, and we don't
 * want to delete valid links to a file from the subvolume if that
 * link is also in the log.
 */
static noinline int backref_in_log(struct btrfs_root *log,
				   struct btrfs_key *key,
				   char *name, int namelen)
{
	struct btrfs_path *path;
	struct btrfs_inode_ref *ref;
	unsigned long ptr;
	unsigned long ptr_end;
	unsigned long name_ptr;
	int found_name_len;
	int item_size;
	int ret;
	int match = 0;

	path = btrfs_alloc_path();
	ret = btrfs_search_slot(NULL, log, key, path, 0, 0);
	if (ret != 0)
		goto out;

	item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
	ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
	ptr_end = ptr + item_size;
	while (ptr < ptr_end) {
		ref = (struct btrfs_inode_ref *)ptr;
		found_name_len = btrfs_inode_ref_name_len(path->nodes[0], ref);
		if (found_name_len == namelen) {
			name_ptr = (unsigned long)(ref + 1);
			ret = memcmp_extent_buffer(path->nodes[0], name,
						   name_ptr, namelen);
			if (ret == 0) {
				match = 1;
				goto out;
			}
		}
		ptr = (unsigned long)(ref + 1) + found_name_len;
	}
out:
	btrfs_free_path(path);
	return match;
}


/*
 * replay one inode back reference item found in the log tree.
 * eb, slot and key refer to the buffer and key found in the log tree.
 * root is the destination we are replaying into, and path is for temp
 * use by this function.  (it should be released on return).
 */
static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
				  struct btrfs_root *root,
				  struct btrfs_root *log,
				  struct btrfs_path *path,
				  struct extent_buffer *eb, int slot,
				  struct btrfs_key *key)
{
	struct inode *dir;
	int ret;
	struct btrfs_key location;
	struct btrfs_inode_ref *ref;
	struct btrfs_dir_item *di;
	struct inode *inode;
	char *name;
	int namelen;
	unsigned long ref_ptr;
	unsigned long ref_end;

	location.objectid = key->objectid;
	location.type = BTRFS_INODE_ITEM_KEY;
	location.offset = 0;

	/*
	 * it is possible that we didn't log all the parent directories
	 * for a given inode.  If we don't find the dir, just don't
	 * copy the back ref in.  The link count fixup code will take
	 * care of the rest
	 */
	dir = read_one_inode(root, key->offset);
	if (!dir)
		return -ENOENT;

	inode = read_one_inode(root, key->objectid);
	BUG_ON(!inode);

	ref_ptr = btrfs_item_ptr_offset(eb, slot);
	ref_end = ref_ptr + btrfs_item_size_nr(eb, slot);

again:
	ref = (struct btrfs_inode_ref *)ref_ptr;

	namelen = btrfs_inode_ref_name_len(eb, ref);
	name = kmalloc(namelen, GFP_NOFS);
	BUG_ON(!name);

	read_extent_buffer(eb, name, (unsigned long)(ref + 1), namelen);

	/* if we already have a perfect match, we're done */
	if (inode_in_dir(root, path, dir->i_ino, inode->i_ino,
			 btrfs_inode_ref_index(eb, ref),
			 name, namelen)) {
		goto out;
	}

	/*
	 * look for a conflicting back reference in the metadata.
	 * if we find one we have to unlink that name of the file
	 * before we add our new link.  Later on, we overwrite any
	 * existing back reference, and we don't want to create
	 * dangling pointers in the directory.
	 */
conflict_again:
	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
	if (ret == 0) {
		char *victim_name;
		int victim_name_len;
		struct btrfs_inode_ref *victim_ref;
		unsigned long ptr;
		unsigned long ptr_end;
		struct extent_buffer *leaf = path->nodes[0];

		/* are we trying to overwrite a back ref for the root directory
		 * if so, just jump out, we're done
		 */
		if (key->objectid == key->offset)
			goto out_nowrite;

		/* check all the names in this back reference to see
		 * if they are in the log.  if so, we allow them to stay
		 * otherwise they must be unlinked as a conflict
		 */
		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
		ptr_end = ptr + btrfs_item_size_nr(leaf, path->slots[0]);
		while (ptr < ptr_end) {
			victim_ref = (struct btrfs_inode_ref *)ptr;
			victim_name_len = btrfs_inode_ref_name_len(leaf,
								   victim_ref);
			victim_name = kmalloc(victim_name_len, GFP_NOFS);
			BUG_ON(!victim_name);

			read_extent_buffer(leaf, victim_name,
					   (unsigned long)(victim_ref + 1),
					   victim_name_len);

			if (!backref_in_log(log, key, victim_name,
					    victim_name_len)) {
				btrfs_inc_nlink(inode);
				btrfs_release_path(root, path);

				ret = btrfs_unlink_inode(trans, root, dir,
							 inode, victim_name,
							 victim_name_len);
				kfree(victim_name);
				btrfs_release_path(root, path);
				goto conflict_again;
			}
			kfree(victim_name);
			ptr = (unsigned long)(victim_ref + 1) + victim_name_len;
		}
		BUG_ON(ret);
	}
	btrfs_release_path(root, path);

	/* look for a conflicting sequence number */
	di = btrfs_lookup_dir_index_item(trans, root, path, dir->i_ino,
					 btrfs_inode_ref_index(eb, ref),
					 name, namelen, 0);
	if (di && !IS_ERR(di)) {
		ret = drop_one_dir_item(trans, root, path, dir, di);
		BUG_ON(ret);
	}
	btrfs_release_path(root, path);


	/* look for a conflicting name */
	di = btrfs_lookup_dir_item(trans, root, path, dir->i_ino,
				   name, namelen, 0);
	if (di && !IS_ERR(di)) {
		ret = drop_one_dir_item(trans, root, path, dir, di);
		BUG_ON(ret);
	}
	btrfs_release_path(root, path);

	/* insert our name */
	ret = btrfs_add_link(trans, dir, inode, name, namelen, 0,
			     btrfs_inode_ref_index(eb, ref));
	BUG_ON(ret);

	btrfs_update_inode(trans, root, inode);

out:
	ref_ptr = (unsigned long)(ref + 1) + namelen;
	kfree(name);
	if (ref_ptr < ref_end)
		goto again;

	/* finally write the back reference in the inode */
	ret = overwrite_item(trans, root, path, eb, slot, key);
	BUG_ON(ret);

out_nowrite:
	btrfs_release_path(root, path);
	iput(dir);
	iput(inode);
	return 0;
}

/*
 * There are a few corners where the link count of the file can't
 * be properly maintained during replay.  So, instead of adding
 * lots of complexity to the log code, we just scan the backrefs
 * for any file that has been through replay.
 *
 * The scan will update the link count on the inode to reflect the
 * number of back refs found.  If it goes down to zero, the iput
 * will free the inode.
 */
static noinline int fixup_inode_link_count(struct btrfs_trans_handle *trans,
					   struct btrfs_root *root,
					   struct inode *inode)
{
	struct btrfs_path *path;
	int ret;
	struct btrfs_key key;
	u64 nlink = 0;
	unsigned long ptr;
	unsigned long ptr_end;
	int name_len;

	key.objectid = inode->i_ino;
	key.type = BTRFS_INODE_REF_KEY;
	key.offset = (u64)-1;

	path = btrfs_alloc_path();

	while (1) {
		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
		if (ret < 0)
			break;
		if (ret > 0) {
			if (path->slots[0] == 0)
				break;
			path->slots[0]--;
		}
		btrfs_item_key_to_cpu(path->nodes[0], &key,
				      path->slots[0]);
		if (key.objectid != inode->i_ino ||
		    key.type != BTRFS_INODE_REF_KEY)
			break;
		ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
		ptr_end = ptr + btrfs_item_size_nr(path->nodes[0],
						   path->slots[0]);
		while (ptr < ptr_end) {
			struct btrfs_inode_ref *ref;

			ref = (struct btrfs_inode_ref *)ptr;
			name_len = btrfs_inode_ref_name_len(path->nodes[0],
							    ref);
			ptr = (unsigned long)(ref + 1) + name_len;
			nlink++;
		}

		if (key.offset == 0)
			break;
		key.offset--;
		btrfs_release_path(root, path);
	}
	btrfs_release_path(root, path);
	if (nlink != inode->i_nlink) {
		inode->i_nlink = nlink;
		btrfs_update_inode(trans, root, inode);
	}
	BTRFS_I(inode)->index_cnt = (u64)-1;

	if (inode->i_nlink == 0 && S_ISDIR(inode->i_mode)) {
		ret = replay_dir_deletes(trans, root, NULL, path,
					 inode->i_ino, 1);
		BUG_ON(ret);
	}
	btrfs_free_path(path);

	return 0;
}

static noinline int fixup_inode_link_counts(struct btrfs_trans_handle *trans,
					    struct btrfs_root *root,
					    struct btrfs_path *path)
{
	int ret;
	struct btrfs_key key;
	struct inode *inode;

	key.objectid = BTRFS_TREE_LOG_FIXUP_OBJECTID;
	key.type = BTRFS_ORPHAN_ITEM_KEY;
	key.offset = (u64)-1;
	while (1) {
		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
		if (ret < 0)
			break;

		if (ret == 1) {
			if (path->slots[0] == 0)
				break;
			path->slots[0]--;
		}

		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
		if (key.objectid != BTRFS_TREE_LOG_FIXUP_OBJECTID ||
		    key.type != BTRFS_ORPHAN_ITEM_KEY)
			break;

		ret = btrfs_del_item(trans, root, path);
		BUG_ON(ret);

		btrfs_release_path(root, path);
		inode = read_one_inode(root, key.offset);
		BUG_ON(!inode);

		ret = fixup_inode_link_count(trans, root, inode);
		BUG_ON(ret);

		iput(inode);

		/*
		 * fixup on a directory may create new entries,
		 * make sure we always look for the highset possible
		 * offset
		 */
		key.offset = (u64)-1;
	}
	btrfs_release_path(root, path);
	return 0;
}


/*
 * record a given inode in the fixup dir so we can check its link
 * count when replay is done.  The link count is incremented here
 * so the inode won't go away until we check it
 */
static noinline int link_to_fixup_dir(struct btrfs_trans_handle *trans,
				      struct btrfs_root *root,
				      struct btrfs_path *path,
				      u64 objectid)
{
	struct btrfs_key key;
	int ret = 0;
	struct inode *inode;

	inode = read_one_inode(root, objectid);
	BUG_ON(!inode);

	key.objectid = BTRFS_TREE_LOG_FIXUP_OBJECTID;
	btrfs_set_key_type(&key, BTRFS_ORPHAN_ITEM_KEY);
	key.offset = objectid;

	ret = btrfs_insert_empty_item(trans, root, path, &key, 0);

	btrfs_release_path(root, path);
	if (ret == 0) {
		btrfs_inc_nlink(inode);
		btrfs_update_inode(trans, root, inode);
	} else if (ret == -EEXIST) {
		ret = 0;
	} else {
		BUG();
	}
	iput(inode);

	return ret;
}

/*
 * when replaying the log for a directory, we only insert names
 * for inodes that actually exist.  This means an fsync on a directory
 * does not implicitly fsync all the new files in it
 */
static noinline int insert_one_name(struct btrfs_trans_handle *trans,
				    struct btrfs_root *root,
				    struct btrfs_path *path,
				    u64 dirid, u64 index,
				    char *name, int name_len, u8 type,
				    struct btrfs_key *location)
{
	struct inode *inode;
	struct inode *dir;
	int ret;

	inode = read_one_inode(root, location->objectid);
	if (!inode)
		return -ENOENT;

	dir = read_one_inode(root, dirid);
	if (!dir) {
		iput(inode);
		return -EIO;
	}
	ret = btrfs_add_link(trans, dir, inode, name, name_len, 1, index);

	/* FIXME, put inode into FIXUP list */

	iput(inode);
	iput(dir);
	return ret;
}

/*
 * take a single entry in a log directory item and replay it into
 * the subvolume.
 *
 * if a conflicting item exists in the subdirectory already,
 * the inode it points to is unlinked and put into the link count
 * fix up tree.
 *
 * If a name from the log points to a file or directory that does
 * not exist in the FS, it is skipped.  fsyncs on directories
 * do not force down inodes inside that directory, just changes to the
 * names or unlinks in a directory.
 */
static noinline int replay_one_name(struct btrfs_trans_handle *trans,
				    struct btrfs_root *root,
				    struct btrfs_path *path,
				    struct extent_buffer *eb,
				    struct btrfs_dir_item *di,
				    struct btrfs_key *key)
{
	char *name;
	int name_len;
	struct btrfs_dir_item *dst_di;
	struct btrfs_key found_key;
	struct btrfs_key log_key;
	struct inode *dir;
	u8 log_type;
	int exists;
	int ret;

	dir = read_one_inode(root, key->objectid);
	BUG_ON(!dir);

	name_len = btrfs_dir_name_len(eb, di);
	name = kmalloc(name_len, GFP_NOFS);
	log_type = btrfs_dir_type(eb, di);
	read_extent_buffer(eb, name, (unsigned long)(di + 1),
		   name_len);

	btrfs_dir_item_key_to_cpu(eb, di, &log_key);
	exists = btrfs_lookup_inode(trans, root, path, &log_key, 0);
	if (exists == 0)
		exists = 1;
	else
		exists = 0;
	btrfs_release_path(root, path);

	if (key->type == BTRFS_DIR_ITEM_KEY) {
		dst_di = btrfs_lookup_dir_item(trans, root, path, key->objectid,
				       name, name_len, 1);
	} else if (key->type == BTRFS_DIR_INDEX_KEY) {
		dst_di = btrfs_lookup_dir_index_item(trans, root, path,
						     key->objectid,
						     key->offset, name,
						     name_len, 1);
	} else {
		BUG();
	}
	if (!dst_di || IS_ERR(dst_di)) {
		/* we need a sequence number to insert, so we only
		 * do inserts for the BTRFS_DIR_INDEX_KEY types
		 */
		if (key->type != BTRFS_DIR_INDEX_KEY)
			goto out;
		goto insert;
	}

	btrfs_dir_item_key_to_cpu(path->nodes[0], dst_di, &found_key);
	/* the existing item matches the logged item */
	if (found_key.objectid == log_key.objectid &&
	    found_key.type == log_key.type &&
	    found_key.offset == log_key.offset &&
	    btrfs_dir_type(path->nodes[0], dst_di) == log_type) {
		goto out;
	}

	/*
	 * don't drop the conflicting directory entry if the inode
	 * for the new entry doesn't exist
	 */
	if (!exists)
		goto out;

	ret = drop_one_dir_item(trans, root, path, dir, dst_di);
	BUG_ON(ret);

	if (key->type == BTRFS_DIR_INDEX_KEY)
		goto insert;
out:
	btrfs_release_path(root, path);
	kfree(name);
	iput(dir);
	return 0;

insert:
	btrfs_release_path(root, path);
	ret = insert_one_name(trans, root, path, key->objectid, key->offset,
			      name, name_len, log_type, &log_key);

	BUG_ON(ret && ret != -ENOENT);
	goto out;
}

/*
 * find all the names in a directory item and reconcile them into
 * the subvolume.  Only BTRFS_DIR_ITEM_KEY types will have more than
 * one name in a directory item, but the same code gets used for
 * both directory index types
 */
static noinline int replay_one_dir_item(struct btrfs_trans_handle *trans,
					struct btrfs_root *root,
					struct btrfs_path *path,
					struct extent_buffer *eb, int slot,
					struct btrfs_key *key)
{
	int ret;
	u32 item_size = btrfs_item_size_nr(eb, slot);
	struct btrfs_dir_item *di;
	int name_len;
	unsigned long ptr;
	unsigned long ptr_end;

	ptr = btrfs_item_ptr_offset(eb, slot);
	ptr_end = ptr + item_size;
	while (ptr < ptr_end) {
		di = (struct btrfs_dir_item *)ptr;
		name_len = btrfs_dir_name_len(eb, di);
		ret = replay_one_name(trans, root, path, eb, di, key);
		BUG_ON(ret);
		ptr = (unsigned long)(di + 1);
		ptr += name_len;
	}
	return 0;
}

/*
 * directory replay has two parts.  There are the standard directory
 * items in the log copied from the subvolume, and range items
 * created in the log while the subvolume was logged.
 *
 * The range items tell us which parts of the key space the log
 * is authoritative for.  During replay, if a key in the subvolume
 * directory is in a logged range item, but not actually in the log
 * that means it was deleted from the directory before the fsync
 * and should be removed.
 */
static noinline int find_dir_range(struct btrfs_root *root,
				   struct btrfs_path *path,
				   u64 dirid, int key_type,
				   u64 *start_ret, u64 *end_ret)
{
	struct btrfs_key key;
	u64 found_end;
	struct btrfs_dir_log_item *item;
	int ret;
	int nritems;

	if (*start_ret == (u64)-1)
		return 1;

	key.objectid = dirid;
	key.type = key_type;
	key.offset = *start_ret;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto out;
	if (ret > 0) {
		if (path->slots[0] == 0)
			goto out;
		path->slots[0]--;
	}
	if (ret != 0)
		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);

	if (key.type != key_type || key.objectid != dirid) {
		ret = 1;
		goto next;
	}
	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
			      struct btrfs_dir_log_item);
	found_end = btrfs_dir_log_end(path->nodes[0], item);

	if (*start_ret >= key.offset && *start_ret <= found_end) {
		ret = 0;
		*start_ret = key.offset;
		*end_ret = found_end;
		goto out;
	}
	ret = 1;
next:
	/* check the next slot in the tree to see if it is a valid item */
	nritems = btrfs_header_nritems(path->nodes[0]);
	if (path->slots[0] >= nritems) {
		ret = btrfs_next_leaf(root, path);
		if (ret)
			goto out;
	} else {
		path->slots[0]++;
	}

	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);

	if (key.type != key_type || key.objectid != dirid) {
		ret = 1;
		goto out;
	}
	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
			      struct btrfs_dir_log_item);
	found_end = btrfs_dir_log_end(path->nodes[0], item);
	*start_ret = key.offset;
	*end_ret = found_end;
	ret = 0;
out:
	btrfs_release_path(root, path);
	return ret;
}

/*
 * this looks for a given directory item in the log.  If the directory
 * item is not in the log, the item is removed and the inode it points
 * to is unlinked
 */
static noinline int check_item_in_log(struct btrfs_trans_handle *trans,
				      struct btrfs_root *root,
				      struct btrfs_root *log,
				      struct btrfs_path *path,
				      struct btrfs_path *log_path,
				      struct inode *dir,
				      struct btrfs_key *dir_key)
{
	int ret;
	struct extent_buffer *eb;
	int slot;
	u32 item_size;
	struct btrfs_dir_item *di;
	struct btrfs_dir_item *log_di;
	int name_len;
	unsigned long ptr;
	unsigned long ptr_end;
	char *name;
	struct inode *inode;
	struct btrfs_key location;

again:
	eb = path->nodes[0];
	slot = path->slots[0];
	item_size = btrfs_item_size_nr(eb, slot);
	ptr = btrfs_item_ptr_offset(eb, slot);
	ptr_end = ptr + item_size;
	while (ptr < ptr_end) {
		di = (struct btrfs_dir_item *)ptr;
		name_len = btrfs_dir_name_len(eb, di);
		name = kmalloc(name_len, GFP_NOFS);
		if (!name) {
			ret = -ENOMEM;
			goto out;
		}
		read_extent_buffer(eb, name, (unsigned long)(di + 1),
				  name_len);
		log_di = NULL;
		if (log && dir_key->type == BTRFS_DIR_ITEM_KEY) {
			log_di = btrfs_lookup_dir_item(trans, log, log_path,
						       dir_key->objectid,
						       name, name_len, 0);
		} else if (log && dir_key->type == BTRFS_DIR_INDEX_KEY) {
			log_di = btrfs_lookup_dir_index_item(trans, log,
						     log_path,
						     dir_key->objectid,
						     dir_key->offset,
						     name, name_len, 0);
		}
		if (!log_di || IS_ERR(log_di)) {
			btrfs_dir_item_key_to_cpu(eb, di, &location);
			btrfs_release_path(root, path);
			btrfs_release_path(log, log_path);
			inode = read_one_inode(root, location.objectid);
			BUG_ON(!inode);

			ret = link_to_fixup_dir(trans, root,
						path, location.objectid);
			BUG_ON(ret);
			btrfs_inc_nlink(inode);
			ret = btrfs_unlink_inode(trans, root, dir, inode,
						 name, name_len);
			BUG_ON(ret);
			kfree(name);
			iput(inode);

			/* there might still be more names under this key
			 * check and repeat if required
			 */
			ret = btrfs_search_slot(NULL, root, dir_key, path,
						0, 0);
			if (ret == 0)
				goto again;
			ret = 0;
			goto out;
		}
		btrfs_release_path(log, log_path);
		kfree(name);

		ptr = (unsigned long)(di + 1);
		ptr += name_len;
	}
	ret = 0;
out:
	btrfs_release_path(root, path);
	btrfs_release_path(log, log_path);
	return ret;
}

/*
 * deletion replay happens before we copy any new directory items
 * out of the log or out of backreferences from inodes.  It
 * scans the log to find ranges of keys that log is authoritative for,
 * and then scans the directory to find items in those ranges that are
 * not present in the log.
 *
 * Anything we don't find in the log is unlinked and removed from the
 * directory.
 */
static noinline int replay_dir_deletes(struct btrfs_trans_handle *trans,
				       struct btrfs_root *root,
				       struct btrfs_root *log,
				       struct btrfs_path *path,
				       u64 dirid, int del_all)
{
	u64 range_start;
	u64 range_end;
	int key_type = BTRFS_DIR_LOG_ITEM_KEY;
	int ret = 0;
	struct btrfs_key dir_key;
	struct btrfs_key found_key;
	struct btrfs_path *log_path;
	struct inode *dir;

	dir_key.objectid = dirid;
	dir_key.type = BTRFS_DIR_ITEM_KEY;
	log_path = btrfs_alloc_path();
	if (!log_path)
		return -ENOMEM;

	dir = read_one_inode(root, dirid);
	/* it isn't an error if the inode isn't there, that can happen
	 * because we replay the deletes before we copy in the inode item
	 * from the log
	 */
	if (!dir) {
		btrfs_free_path(log_path);
		return 0;
	}
again:
	range_start = 0;
	range_end = 0;
	while (1) {
		if (del_all)
			range_end = (u64)-1;
		else {
			ret = find_dir_range(log, path, dirid, key_type,
					     &range_start, &range_end);
			if (ret != 0)
				break;
		}

		dir_key.offset = range_start;
		while (1) {
			int nritems;
			ret = btrfs_search_slot(NULL, root, &dir_key, path,
						0, 0);
			if (ret < 0)
				goto out;

			nritems = btrfs_header_nritems(path->nodes[0]);
			if (path->slots[0] >= nritems) {
				ret = btrfs_next_leaf(root, path);
				if (ret)
					break;
			}
			btrfs_item_key_to_cpu(path->nodes[0], &found_key,
					      path->slots[0]);
			if (found_key.objectid != dirid ||
			    found_key.type != dir_key.type)
				goto next_type;

			if (found_key.offset > range_end)
				break;

			ret = check_item_in_log(trans, root, log, path,
						log_path, dir,
						&found_key);
			BUG_ON(ret);
			if (found_key.offset == (u64)-1)
				break;
			dir_key.offset = found_key.offset + 1;
		}
		btrfs_release_path(root, path);
		if (range_end == (u64)-1)
			break;
		range_start = range_end + 1;
	}

next_type:
	ret = 0;
	if (key_type == BTRFS_DIR_LOG_ITEM_KEY) {
		key_type = BTRFS_DIR_LOG_INDEX_KEY;
		dir_key.type = BTRFS_DIR_INDEX_KEY;
		btrfs_release_path(root, path);
		goto again;
	}
out:
	btrfs_release_path(root, path);
	btrfs_free_path(log_path);
	iput(dir);
	return ret;
}

/*
 * the process_func used to replay items from the log tree.  This
 * gets called in two different stages.  The first stage just looks
 * for inodes and makes sure they are all copied into the subvolume.
 *
 * The second stage copies all the other item types from the log into
 * the subvolume.  The two stage approach is slower, but gets rid of
 * lots of complexity around inodes referencing other inodes that exist
 * only in the log (references come from either directory items or inode
 * back refs).
 */
static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
			     struct walk_control *wc, u64 gen)
{
	int nritems;
	struct btrfs_path *path;
	struct btrfs_root *root = wc->replay_dest;
	struct btrfs_key key;
	u32 item_size;
	int level;
	int i;
	int ret;

	btrfs_read_buffer(eb, gen);

	level = btrfs_header_level(eb);

	if (level != 0)
		return 0;

	path = btrfs_alloc_path();
	BUG_ON(!path);

	nritems = btrfs_header_nritems(eb);
	for (i = 0; i < nritems; i++) {
		btrfs_item_key_to_cpu(eb, &key, i);
		item_size = btrfs_item_size_nr(eb, i);

		/* inode keys are done during the first stage */
		if (key.type == BTRFS_INODE_ITEM_KEY &&
		    wc->stage == LOG_WALK_REPLAY_INODES) {
			struct inode *inode;
			struct btrfs_inode_item *inode_item;
			u32 mode;

			inode_item = btrfs_item_ptr(eb, i,
					    struct btrfs_inode_item);
			mode = btrfs_inode_mode(eb, inode_item);
			if (S_ISDIR(mode)) {
				ret = replay_dir_deletes(wc->trans,
					 root, log, path, key.objectid, 0);
				BUG_ON(ret);
			}
			ret = overwrite_item(wc->trans, root, path,
					     eb, i, &key);
			BUG_ON(ret);

			/* for regular files, truncate away
			 * extents past the new EOF
			 */
			if (S_ISREG(mode)) {
				inode = read_one_inode(root,
						       key.objectid);
				BUG_ON(!inode);

				ret = btrfs_truncate_inode_items(wc->trans,
					root, inode, inode->i_size,
					BTRFS_EXTENT_DATA_KEY);
				BUG_ON(ret);

				/* if the nlink count is zero here, the iput
				 * will free the inode.  We bump it to make
				 * sure it doesn't get freed until the link
				 * count fixup is done
				 */
				if (inode->i_nlink == 0) {
					btrfs_inc_nlink(inode);
					btrfs_update_inode(wc->trans,
							   root, inode);
				}
				iput(inode);
			}
			ret = link_to_fixup_dir(wc->trans, root,
						path, key.objectid);
			BUG_ON(ret);
		}
		if (wc->stage < LOG_WALK_REPLAY_ALL)
			continue;

		/* these keys are simply copied */
		if (key.type == BTRFS_XATTR_ITEM_KEY) {
			ret = overwrite_item(wc->trans, root, path,
					     eb, i, &key);
			BUG_ON(ret);
		} else if (key.type == BTRFS_INODE_REF_KEY) {
			ret = add_inode_ref(wc->trans, root, log, path,
					    eb, i, &key);
			BUG_ON(ret && ret != -ENOENT);
		} else if (key.type == BTRFS_EXTENT_DATA_KEY) {
			ret = replay_one_extent(wc->trans, root, path,
						eb, i, &key);
			BUG_ON(ret);
		} else if (key.type == BTRFS_DIR_ITEM_KEY ||
			   key.type == BTRFS_DIR_INDEX_KEY) {
			ret = replay_one_dir_item(wc->trans, root, path,
						  eb, i, &key);
			BUG_ON(ret);
		}
	}
	btrfs_free_path(path);
	return 0;
}

static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
				   struct btrfs_root *root,
				   struct btrfs_path *path, int *level,
				   struct walk_control *wc)
{
	u64 root_owner;
	u64 root_gen;
	u64 bytenr;
	u64 ptr_gen;
	struct extent_buffer *next;
	struct extent_buffer *cur;
	struct extent_buffer *parent;
	u32 blocksize;
	int ret = 0;

	WARN_ON(*level < 0);
	WARN_ON(*level >= BTRFS_MAX_LEVEL);

	while (*level > 0) {
		WARN_ON(*level < 0);
		WARN_ON(*level >= BTRFS_MAX_LEVEL);
		cur = path->nodes[*level];

		if (btrfs_header_level(cur) != *level)
			WARN_ON(1);

		if (path->slots[*level] >=
		    btrfs_header_nritems(cur))
			break;

		bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
		ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
		blocksize = btrfs_level_size(root, *level - 1);

		parent = path->nodes[*level];
		root_owner = btrfs_header_owner(parent);
		root_gen = btrfs_header_generation(parent);

		next = btrfs_find_create_tree_block(root, bytenr, blocksize);

		wc->process_func(root, next, wc, ptr_gen);

		if (*level == 1) {
			path->slots[*level]++;
			if (wc->free) {
				btrfs_read_buffer(next, ptr_gen);

				btrfs_tree_lock(next);
				clean_tree_block(trans, root, next);
				btrfs_set_lock_blocking(next);
				btrfs_wait_tree_block_writeback(next);
				btrfs_tree_unlock(next);

				WARN_ON(root_owner !=
					BTRFS_TREE_LOG_OBJECTID);
				ret = btrfs_free_reserved_extent(root,
							 bytenr, blocksize);
				BUG_ON(ret);
			}
			free_extent_buffer(next);
			continue;
		}
		btrfs_read_buffer(next, ptr_gen);

		WARN_ON(*level <= 0);
		if (path->nodes[*level-1])
			free_extent_buffer(path->nodes[*level-1]);
		path->nodes[*level-1] = next;
		*level = btrfs_header_level(next);
		path->slots[*level] = 0;
		cond_resched();
	}
	WARN_ON(*level < 0);
	WARN_ON(*level >= BTRFS_MAX_LEVEL);

	if (path->nodes[*level] == root->node)
		parent = path->nodes[*level];
	else
		parent = path->nodes[*level + 1];

	bytenr = path->nodes[*level]->start;

	blocksize = btrfs_level_size(root, *level);
	root_owner = btrfs_header_owner(parent);
	root_gen = btrfs_header_generation(parent);

	wc->process_func(root, path->nodes[*level], wc,
			 btrfs_header_generation(path->nodes[*level]));

	if (wc->free) {
		next = path->nodes[*level];
		btrfs_tree_lock(next);
		clean_tree_block(trans, root, next);
		btrfs_set_lock_blocking(next);
		btrfs_wait_tree_block_writeback(next);
		btrfs_tree_unlock(next);

		WARN_ON(root_owner != BTRFS_TREE_LOG_OBJECTID);
		ret = btrfs_free_reserved_extent(root, bytenr, blocksize);
		BUG_ON(ret);
	}
	free_extent_buffer(path->nodes[*level]);
	path->nodes[*level] = NULL;
	*level += 1;

	cond_resched();
	return 0;
}

static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
				 struct btrfs_root *root,
				 struct btrfs_path *path, int *level,
				 struct walk_control *wc)
{
	u64 root_owner;
	u64 root_gen;
	int i;
	int slot;
	int ret;

	for (i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
		slot = path->slots[i];
		if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
			struct extent_buffer *node;
			node = path->nodes[i];
			path->slots[i]++;
			*level = i;
			WARN_ON(*level == 0);
			return 0;
		} else {
			struct extent_buffer *parent;
			if (path->nodes[*level] == root->node)
				parent = path->nodes[*level];
			else
				parent = path->nodes[*level + 1];

			root_owner = btrfs_header_owner(parent);
			root_gen = btrfs_header_generation(parent);
			wc->process_func(root, path->nodes[*level], wc,
				 btrfs_header_generation(path->nodes[*level]));
			if (wc->free) {
				struct extent_buffer *next;

				next = path->nodes[*level];

				btrfs_tree_lock(next);
				clean_tree_block(trans, root, next);
				btrfs_set_lock_blocking(next);
				btrfs_wait_tree_block_writeback(next);
				btrfs_tree_unlock(next);

				WARN_ON(root_owner != BTRFS_TREE_LOG_OBJECTID);
				ret = btrfs_free_reserved_extent(root,
						path->nodes[*level]->start,
						path->nodes[*level]->len);
				BUG_ON(ret);
			}
			free_extent_buffer(path->nodes[*level]);
			path->nodes[*level] = NULL;
			*level = i + 1;
		}
	}
	return 1;
}

/*
 * drop the reference count on the tree rooted at 'snap'.  This traverses
 * the tree freeing any blocks that have a ref count of zero after being
 * decremented.
 */
static int walk_log_tree(struct btrfs_trans_handle *trans,
			 struct btrfs_root *log, struct walk_control *wc)
{
	int ret = 0;
	int wret;
	int level;
	struct btrfs_path *path;
	int i;
	int orig_level;

	path = btrfs_alloc_path();
	BUG_ON(!path);

	level = btrfs_header_level(log->node);
	orig_level = level;
	path->nodes[level] = log->node;
	extent_buffer_get(log->node);
	path->slots[level] = 0;

	while (1) {
		wret = walk_down_log_tree(trans, log, path, &level, wc);
		if (wret > 0)
			break;
		if (wret < 0)
			ret = wret;

		wret = walk_up_log_tree(trans, log, path, &level, wc);
		if (wret > 0)
			break;
		if (wret < 0)
			ret = wret;
	}

	/* was the root node processed? if not, catch it here */
	if (path->nodes[orig_level]) {
		wc->process_func(log, path->nodes[orig_level], wc,
			 btrfs_header_generation(path->nodes[orig_level]));
		if (wc->free) {
			struct extent_buffer *next;

			next = path->nodes[orig_level];

			btrfs_tree_lock(next);
			clean_tree_block(trans, log, next);
			btrfs_set_lock_blocking(next);
			btrfs_wait_tree_block_writeback(next);
			btrfs_tree_unlock(next);

			WARN_ON(log->root_key.objectid !=
				BTRFS_TREE_LOG_OBJECTID);
			ret = btrfs_free_reserved_extent(log, next->start,
							 next->len);
			BUG_ON(ret);
		}
	}

	for (i = 0; i <= orig_level; i++) {
		if (path->nodes[i]) {
			free_extent_buffer(path->nodes[i]);
			path->nodes[i] = NULL;
		}
	}
	btrfs_free_path(path);
	return ret;
}

/*
 * helper function to update the item for a given subvolumes log root
 * in the tree of log roots
 */
static int update_log_root(struct btrfs_trans_handle *trans,
			   struct btrfs_root *log)
{
	int ret;

	if (log->log_transid == 1) {
		/* insert root item on the first sync */
		ret = btrfs_insert_root(trans, log->fs_info->log_root_tree,
				&log->root_key, &log->root_item);
	} else {
		ret = btrfs_update_root(trans, log->fs_info->log_root_tree,
				&log->root_key, &log->root_item);
	}
	return ret;
}

static int wait_log_commit(struct btrfs_trans_handle *trans,
			   struct btrfs_root *root, unsigned long transid)
{
	DEFINE_WAIT(wait);
	int index = transid % 2;

	/*
	 * we only allow two pending log transactions at a time,
	 * so we know that if ours is more than 2 older than the
	 * current transaction, we're done
	 */
	do {
		prepare_to_wait(&root->log_commit_wait[index],
				&wait, TASK_UNINTERRUPTIBLE);
		mutex_unlock(&root->log_mutex);

		if (root->fs_info->last_trans_log_full_commit !=
		    trans->transid && root->log_transid < transid + 2 &&
		    atomic_read(&root->log_commit[index]))
			schedule();

		finish_wait(&root->log_commit_wait[index], &wait);
		mutex_lock(&root->log_mutex);
	} while (root->log_transid < transid + 2 &&
		 atomic_read(&root->log_commit[index]));
	return 0;
}

static int wait_for_writer(struct btrfs_trans_handle *trans,
			   struct btrfs_root *root)
{
	DEFINE_WAIT(wait);
	while (atomic_read(&root->log_writers)) {
		prepare_to_wait(&root->log_writer_wait,
				&wait, TASK_UNINTERRUPTIBLE);
		mutex_unlock(&root->log_mutex);
		if (root->fs_info->last_trans_log_full_commit !=
		    trans->transid && atomic_read(&root->log_writers))
			schedule();
		mutex_lock(&root->log_mutex);
		finish_wait(&root->log_writer_wait, &wait);
	}
	return 0;
}

/*
 * btrfs_sync_log does sends a given tree log down to the disk and
 * updates the super blocks to record it.  When this call is done,
 * you know that any inodes previously logged are safely on disk only
 * if it returns 0.
 *
 * Any other return value means you need to call btrfs_commit_transaction.
 * Some of the edge cases for fsyncing directories that have had unlinks
 * or renames done in the past mean that sometimes the only safe
 * fsync is to commit the whole FS.  When btrfs_sync_log returns -EAGAIN,
 * that has happened.
 */
int btrfs_sync_log(struct btrfs_trans_handle *trans,
		   struct btrfs_root *root)
{
	int index1;
	int index2;
	int ret;
	struct btrfs_root *log = root->log_root;
	struct btrfs_root *log_root_tree = root->fs_info->log_root_tree;
	u64 log_transid = 0;

	mutex_lock(&root->log_mutex);
	index1 = root->log_transid % 2;
	if (atomic_read(&root->log_commit[index1])) {
		wait_log_commit(trans, root, root->log_transid);
		mutex_unlock(&root->log_mutex);
		return 0;
	}
	atomic_set(&root->log_commit[index1], 1);

	/* wait for previous tree log sync to complete */
	if (atomic_read(&root->log_commit[(index1 + 1) % 2]))
		wait_log_commit(trans, root, root->log_transid - 1);

	while (root->log_multiple_pids) {
		unsigned long batch = root->log_batch;
		mutex_unlock(&root->log_mutex);
		schedule_timeout_uninterruptible(1);
		mutex_lock(&root->log_mutex);

		wait_for_writer(trans, root);
		if (batch == root->log_batch)
			break;
	}

	/* bail out if we need to do a full commit */
	if (root->fs_info->last_trans_log_full_commit == trans->transid) {
		ret = -EAGAIN;
		mutex_unlock(&root->log_mutex);
		goto out;
	}

	ret = btrfs_write_and_wait_marked_extents(log, &log->dirty_log_pages);
	BUG_ON(ret);

	btrfs_set_root_node(&log->root_item, log->node);

	root->log_batch = 0;
	log_transid = root->log_transid;
	root->log_transid++;
	log->log_transid = root->log_transid;
	root->log_start_pid = 0;
	smp_mb();
	/*
	 * log tree has been flushed to disk, new modifications of
	 * the log will be written to new positions. so it's safe to
	 * allow log writers to go in.
	 */
	mutex_unlock(&root->log_mutex);

	mutex_lock(&log_root_tree->log_mutex);
	log_root_tree->log_batch++;
	atomic_inc(&log_root_tree->log_writers);
	mutex_unlock(&log_root_tree->log_mutex);

	ret = update_log_root(trans, log);
	BUG_ON(ret);

	mutex_lock(&log_root_tree->log_mutex);
	if (atomic_dec_and_test(&log_root_tree->log_writers)) {
		smp_mb();
		if (waitqueue_active(&log_root_tree->log_writer_wait))
			wake_up(&log_root_tree->log_writer_wait);
	}

	index2 = log_root_tree->log_transid % 2;
	if (atomic_read(&log_root_tree->log_commit[index2])) {
		wait_log_commit(trans, log_root_tree,
				log_root_tree->log_transid);
		mutex_unlock(&log_root_tree->log_mutex);
		goto out;
	}
	atomic_set(&log_root_tree->log_commit[index2], 1);

	if (atomic_read(&log_root_tree->log_commit[(index2 + 1) % 2])) {
		wait_log_commit(trans, log_root_tree,
				log_root_tree->log_transid - 1);
	}

	wait_for_writer(trans, log_root_tree);

	/*
	 * now that we've moved on to the tree of log tree roots,
	 * check the full commit flag again
	 */
	if (root->fs_info->last_trans_log_full_commit == trans->transid) {
		mutex_unlock(&log_root_tree->log_mutex);
		ret = -EAGAIN;
		goto out_wake_log_root;
	}

	ret = btrfs_write_and_wait_marked_extents(log_root_tree,
				&log_root_tree->dirty_log_pages);
	BUG_ON(ret);

	btrfs_set_super_log_root(&root->fs_info->super_for_commit,
				log_root_tree->node->start);
	btrfs_set_super_log_root_level(&root->fs_info->super_for_commit,
				btrfs_header_level(log_root_tree->node));

	log_root_tree->log_batch = 0;
	log_root_tree->log_transid++;
	smp_mb();

	mutex_unlock(&log_root_tree->log_mutex);

	/*
	 * nobody else is going to jump in and write the the ctree
	 * super here because the log_commit atomic below is protecting
	 * us.  We must be called with a transaction handle pinning
	 * the running transaction open, so a full commit can't hop
	 * in and cause problems either.
	 */
	write_ctree_super(trans, root->fs_info->tree_root, 1);
	ret = 0;

	mutex_lock(&root->log_mutex);
	if (root->last_log_commit < log_transid)
		root->last_log_commit = log_transid;
	mutex_unlock(&root->log_mutex);

out_wake_log_root:
	atomic_set(&log_root_tree->log_commit[index2], 0);
	smp_mb();
	if (waitqueue_active(&log_root_tree->log_commit_wait[index2]))
		wake_up(&log_root_tree->log_commit_wait[index2]);
out:
	atomic_set(&root->log_commit[index1], 0);
	smp_mb();
	if (waitqueue_active(&root->log_commit_wait[index1]))
		wake_up(&root->log_commit_wait[index1]);
	return 0;
}

/*
 * free all the extents used by the tree log.  This should be called
 * at commit time of the full transaction
 */
int btrfs_free_log(struct btrfs_trans_handle *trans, struct btrfs_root *root)
{
	int ret;
	struct btrfs_root *log;
	struct key;
	u64 start;
	u64 end;
	struct walk_control wc = {
		.free = 1,
		.process_func = process_one_buffer
	};

	if (!root->log_root || root->fs_info->log_root_recovering)
		return 0;

	log = root->log_root;
	ret = walk_log_tree(trans, log, &wc);
	BUG_ON(ret);

	while (1) {
		ret = find_first_extent_bit(&log->dirty_log_pages,
				    0, &start, &end, EXTENT_DIRTY);
		if (ret)
			break;

		clear_extent_dirty(&log->dirty_log_pages,
				   start, end, GFP_NOFS);
	}

	if (log->log_transid > 0) {
		ret = btrfs_del_root(trans, root->fs_info->log_root_tree,
				     &log->root_key);
		BUG_ON(ret);
	}
	root->log_root = NULL;
	free_extent_buffer(log->node);
	kfree(log);
	return 0;
}

/*
 * If both a file and directory are logged, and unlinks or renames are
 * mixed in, we have a few interesting corners:
 *
 * create file X in dir Y
 * link file X to X.link in dir Y
 * fsync file X
 * unlink file X but leave X.link
 * fsync dir Y
 *
 * After a crash we would expect only X.link to exist.  But file X
 * didn't get fsync'd again so the log has back refs for X and X.link.
 *
 * We solve this by removing directory entries and inode backrefs from the
 * log when a file that was logged in the current transaction is
 * unlinked.  Any later fsync will include the updated log entries, and
 * we'll be able to reconstruct the proper directory items from backrefs.
 *
 * This optimizations allows us to avoid relogging the entire inode
 * or the entire directory.
 */
int btrfs_del_dir_entries_in_log(struct btrfs_trans_handle *trans,
				 struct btrfs_root *root,
				 const char *name, int name_len,
				 struct inode *dir, u64 index)
{
	struct btrfs_root *log;
	struct btrfs_dir_item *di;
	struct btrfs_path *path;
	int ret;
	int bytes_del = 0;

	if (BTRFS_I(dir)->logged_trans < trans->transid)
		return 0;

	ret = join_running_log_trans(root);
	if (ret)
		return 0;

	mutex_lock(&BTRFS_I(dir)->log_mutex);

	log = root->log_root;
	path = btrfs_alloc_path();
	di = btrfs_lookup_dir_item(trans, log, path, dir->i_ino,
				   name, name_len, -1);
	if (di && !IS_ERR(di)) {
		ret = btrfs_delete_one_dir_name(trans, log, path, di);
		bytes_del += name_len;
		BUG_ON(ret);
	}
	btrfs_release_path(log, path);
	di = btrfs_lookup_dir_index_item(trans, log, path, dir->i_ino,
					 index, name, name_len, -1);
	if (di && !IS_ERR(di)) {
		ret = btrfs_delete_one_dir_name(trans, log, path, di);
		bytes_del += name_len;
		BUG_ON(ret);
	}

	/* update the directory size in the log to reflect the names
	 * we have removed
	 */
	if (bytes_del) {
		struct btrfs_key key;

		key.objectid = dir->i_ino;
		key.offset = 0;
		key.type = BTRFS_INODE_ITEM_KEY;
		btrfs_release_path(log, path);

		ret = btrfs_search_slot(trans, log, &key, path, 0, 1);
		if (ret == 0) {
			struct btrfs_inode_item *item;
			u64 i_size;

			item = btrfs_item_ptr(path->nodes[0], path->slots[0],
					      struct btrfs_inode_item);
			i_size = btrfs_inode_size(path->nodes[0], item);
			if (i_size > bytes_del)
				i_size -= bytes_del;
			else
				i_size = 0;
			btrfs_set_inode_size(path->nodes[0], item, i_size);
			btrfs_mark_buffer_dirty(path->nodes[0]);
		} else
			ret = 0;
		btrfs_release_path(log, path);
	}

	btrfs_free_path(path);
	mutex_unlock(&BTRFS_I(dir)->log_mutex);
	btrfs_end_log_trans(root);

	return 0;
}

/* see comments for btrfs_del_dir_entries_in_log */
int btrfs_del_inode_ref_in_log(struct btrfs_trans_handle *trans,
			       struct btrfs_root *root,
			       const char *name, int name_len,
			       struct inode *inode, u64 dirid)
{
	struct btrfs_root *log;
	u64 index;
	int ret;

	if (BTRFS_I(inode)->logged_trans < trans->transid)
		return 0;

	ret = join_running_log_trans(root);
	if (ret)
		return 0;
	log = root->log_root;
	mutex_lock(&BTRFS_I(inode)->log_mutex);

	ret = btrfs_del_inode_ref(trans, log, name, name_len, inode->i_ino,
				  dirid, &index);
	mutex_unlock(&BTRFS_I(inode)->log_mutex);
	btrfs_end_log_trans(root);

	return ret;
}

/*
 * creates a range item in the log for 'dirid'.  first_offset and
 * last_offset tell us which parts of the key space the log should
 * be considered authoritative for.
 */
static noinline int insert_dir_log_key(struct btrfs_trans_handle *trans,
				       struct btrfs_root *log,
				       struct btrfs_path *path,
				       int key_type, u64 dirid,
				       u64 first_offset, u64 last_offset)
{
	int ret;
	struct btrfs_key key;
	struct btrfs_dir_log_item *item;

	key.objectid = dirid;
	key.offset = first_offset;
	if (key_type == BTRFS_DIR_ITEM_KEY)
		key.type = BTRFS_DIR_LOG_ITEM_KEY;
	else
		key.type = BTRFS_DIR_LOG_INDEX_KEY;
	ret = btrfs_insert_empty_item(trans, log, path, &key, sizeof(*item));
	BUG_ON(ret);

	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
			      struct btrfs_dir_log_item);
	btrfs_set_dir_log_end(path->nodes[0], item, last_offset);
	btrfs_mark_buffer_dirty(path->nodes[0]);
	btrfs_release_path(log, path);
	return 0;
}

/*
 * log all the items included in the current transaction for a given
 * directory.  This also creates the range items in the log tree required
 * to replay anything deleted before the fsync
 */
static noinline int log_dir_items(struct btrfs_trans_handle *trans,
			  struct btrfs_root *root, struct inode *inode,
			  struct btrfs_path *path,
			  struct btrfs_path *dst_path, int key_type,
			  u64 min_offset, u64 *last_offset_ret)
{
	struct btrfs_key min_key;
	struct btrfs_key max_key;
	struct btrfs_root *log = root->log_root;
	struct extent_buffer *src;
	int ret;
	int i;
	int nritems;
	u64 first_offset = min_offset;
	u64 last_offset = (u64)-1;

	log = root->log_root;
	max_key.objectid = inode->i_ino;
	max_key.offset = (u64)-1;
	max_key.type = key_type;

	min_key.objectid = inode->i_ino;
	min_key.type = key_type;
	min_key.offset = min_offset;

	path->keep_locks = 1;

	ret = btrfs_search_forward(root, &min_key, &max_key,
				   path, 0, trans->transid);

	/*
	 * we didn't find anything from this transaction, see if there
	 * is anything at all
	 */
	if (ret != 0 || min_key.objectid != inode->i_ino ||
	    min_key.type != key_type) {
		min_key.objectid = inode->i_ino;
		min_key.type = key_type;
		min_key.offset = (u64)-1;
		btrfs_release_path(root, path);
		ret = btrfs_search_slot(NULL, root, &min_key, path, 0, 0);
		if (ret < 0) {
			btrfs_release_path(root, path);
			return ret;
		}
		ret = btrfs_previous_item(root, path, inode->i_ino, key_type);

		/* if ret == 0 there are items for this type,
		 * create a range to tell us the last key of this type.
		 * otherwise, there are no items in this directory after
		 * *min_offset, and we create a range to indicate that.
		 */
		if (ret == 0) {
			struct btrfs_key tmp;
			btrfs_item_key_to_cpu(path->nodes[0], &tmp,
					      path->slots[0]);
			if (key_type == tmp.type)
				first_offset = max(min_offset, tmp.offset) + 1;
		}
		goto done;
	}

	/* go backward to find any previous key */
	ret = btrfs_previous_item(root, path, inode->i_ino, key_type);
	if (ret == 0) {
		struct btrfs_key tmp;
		btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);
		if (key_type == tmp.type) {
			first_offset = tmp.offset;
			ret = overwrite_item(trans, log, dst_path,
					     path->nodes[0], path->slots[0],
					     &tmp);
		}
	}
	btrfs_release_path(root, path);

	/* find the first key from this transaction again */
	ret = btrfs_search_slot(NULL, root, &min_key, path, 0, 0);
	if (ret != 0) {
		WARN_ON(1);
		goto done;
	}

	/*
	 * we have a block from this transaction, log every item in it
	 * from our directory
	 */
	while (1) {
		struct btrfs_key tmp;
		src = path->nodes[0];
		nritems = btrfs_header_nritems(src);
		for (i = path->slots[0]; i < nritems; i++) {
			btrfs_item_key_to_cpu(src, &min_key, i);

			if (min_key.objectid != inode->i_ino ||
			    min_key.type != key_type)
				goto done;
			ret = overwrite_item(trans, log, dst_path, src, i,
					     &min_key);
			BUG_ON(ret);
		}
		path->slots[0] = nritems;

		/*
		 * look ahead to the next item and see if it is also
		 * from this directory and from this transaction
		 */
		ret = btrfs_next_leaf(root, path);
		if (ret == 1) {
			last_offset = (u64)-1;
			goto done;
		}
		btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);
		if (tmp.objectid != inode->i_ino || tmp.type != key_type) {
			last_offset = (u64)-1;
			goto done;
		}
		if (btrfs_header_generation(path->nodes[0]) != trans->transid) {
			ret = overwrite_item(trans, log, dst_path,
					     path->nodes[0], path->slots[0],
					     &tmp);

			BUG_ON(ret);
			last_offset = tmp.offset;
			goto done;
		}
	}
done:
	*last_offset_ret = last_offset;
	btrfs_release_path(root, path);
	btrfs_release_path(log, dst_path);

	/* insert the log range keys to indicate where the log is valid */
	ret = insert_dir_log_key(trans, log, path, key_type, inode->i_ino,
				 first_offset, last_offset);
	BUG_ON(ret);
	return 0;
}

/*
 * logging directories is very similar to logging inodes, We find all the items
 * from the current transaction and write them to the log.
 *
 * The recovery code scans the directory in the subvolume, and if it finds a
 * key in the range logged that is not present in the log tree, then it means
 * that dir entry was unlinked during the transaction.
 *
 * In order for that scan to work, we must include one key smaller than
 * the smallest logged by this transaction and one key larger than the largest
 * key logged by this transaction.
 */
static noinline int log_directory_changes(struct btrfs_trans_handle *trans,
			  struct btrfs_root *root, struct inode *inode,
			  struct btrfs_path *path,
			  struct btrfs_path *dst_path)
{
	u64 min_key;
	u64 max_key;
	int ret;
	int key_type = BTRFS_DIR_ITEM_KEY;

again:
	min_key = 0;
	max_key = 0;
	while (1) {
		ret = log_dir_items(trans, root, inode, path,
				    dst_path, key_type, min_key,
				    &max_key);
		BUG_ON(ret);
		if (max_key == (u64)-1)
			break;
		min_key = max_key + 1;
	}

	if (key_type == BTRFS_DIR_ITEM_KEY) {
		key_type = BTRFS_DIR_INDEX_KEY;
		goto again;
	}
	return 0;
}

/*
 * a helper function to drop items from the log before we relog an
 * inode.  max_key_type indicates the highest item type to remove.
 * This cannot be run for file data extents because it does not
 * free the extents they point to.
 */
static int drop_objectid_items(struct btrfs_trans_handle *trans,
				  struct btrfs_root *log,
				  struct btrfs_path *path,
				  u64 objectid, int max_key_type)
{
	int ret;
	struct btrfs_key key;
	struct btrfs_key found_key;

	key.objectid = objectid;
	key.type = max_key_type;
	key.offset = (u64)-1;

	while (1) {
		ret = btrfs_search_slot(trans, log, &key, path, -1, 1);

		if (ret != 1)
			break;

		if (path->slots[0] == 0)
			break;

		path->slots[0]--;
		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
				      path->slots[0]);

		if (found_key.objectid != objectid)
			break;

		ret = btrfs_del_item(trans, log, path);
		BUG_ON(ret);
		btrfs_release_path(log, path);
	}
	btrfs_release_path(log, path);
	return 0;
}

static noinline int copy_items(struct btrfs_trans_handle *trans,
			       struct btrfs_root *log,
			       struct btrfs_path *dst_path,
			       struct extent_buffer *src,
			       int start_slot, int nr, int inode_only)
{
	unsigned long src_offset;
	unsigned long dst_offset;
	struct btrfs_file_extent_item *extent;
	struct btrfs_inode_item *inode_item;
	int ret;
	struct btrfs_key *ins_keys;
	u32 *ins_sizes;
	char *ins_data;
	int i;
	struct list_head ordered_sums;

	INIT_LIST_HEAD(&ordered_sums);

	ins_data = kmalloc(nr * sizeof(struct btrfs_key) +
			   nr * sizeof(u32), GFP_NOFS);
	ins_sizes = (u32 *)ins_data;
	ins_keys = (struct btrfs_key *)(ins_data + nr * sizeof(u32));

	for (i = 0; i < nr; i++) {
		ins_sizes[i] = btrfs_item_size_nr(src, i + start_slot);
		btrfs_item_key_to_cpu(src, ins_keys + i, i + start_slot);
	}
	ret = btrfs_insert_empty_items(trans, log, dst_path,
				       ins_keys, ins_sizes, nr);
	BUG_ON(ret);

	for (i = 0; i < nr; i++, dst_path->slots[0]++) {
		dst_offset = btrfs_item_ptr_offset(dst_path->nodes[0],
						   dst_path->slots[0]);

		src_offset = btrfs_item_ptr_offset(src, start_slot + i);

		copy_extent_buffer(dst_path->nodes[0], src, dst_offset,
				   src_offset, ins_sizes[i]);

		if (inode_only == LOG_INODE_EXISTS &&
		    ins_keys[i].type == BTRFS_INODE_ITEM_KEY) {
			inode_item = btrfs_item_ptr(dst_path->nodes[0],
						    dst_path->slots[0],
						    struct btrfs_inode_item);
			btrfs_set_inode_size(dst_path->nodes[0], inode_item, 0);

			/* set the generation to zero so the recover code
			 * can tell the difference between an logging
			 * just to say 'this inode exists' and a logging
			 * to say 'update this inode with these values'
			 */
			btrfs_set_inode_generation(dst_path->nodes[0],
						   inode_item, 0);
		}
		/* take a reference on file data extents so that truncates
		 * or deletes of this inode don't have to relog the inode
		 * again
		 */
		if (btrfs_key_type(ins_keys + i) == BTRFS_EXTENT_DATA_KEY) {
			int found_type;
			extent = btrfs_item_ptr(src, start_slot + i,
						struct btrfs_file_extent_item);

			found_type = btrfs_file_extent_type(src, extent);
			if (found_type == BTRFS_FILE_EXTENT_REG ||
			    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
				u64 ds, dl, cs, cl;
				ds = btrfs_file_extent_disk_bytenr(src,
								extent);
				/* ds == 0 is a hole */
				if (ds == 0)
					continue;

				dl = btrfs_file_extent_disk_num_bytes(src,
								extent);
				cs = btrfs_file_extent_offset(src, extent);
				cl = btrfs_file_extent_num_bytes(src,
								extent);;
				if (btrfs_file_extent_compression(src,
								  extent)) {
					cs = 0;
					cl = dl;
				}

				ret = btrfs_lookup_csums_range(
						log->fs_info->csum_root,
						ds + cs, ds + cs + cl - 1,
						&ordered_sums);
				BUG_ON(ret);
			}
		}
	}

	btrfs_mark_buffer_dirty(dst_path->nodes[0]);
	btrfs_release_path(log, dst_path);
	kfree(ins_data);

	/*
	 * we have to do this after the loop above to avoid changing the
	 * log tree while trying to change the log tree.
	 */
	while (!list_empty(&ordered_sums)) {
		struct btrfs_ordered_sum *sums = list_entry(ordered_sums.next,
						   struct btrfs_ordered_sum,
						   list);
		ret = btrfs_csum_file_blocks(trans, log, sums);
		BUG_ON(ret);
		list_del(&sums->list);
		kfree(sums);
	}
	return 0;
}

/* log a single inode in the tree log.
 * At least one parent directory for this inode must exist in the tree
 * or be logged already.
 *
 * Any items from this inode changed by the current transaction are copied
 * to the log tree.  An extra reference is taken on any extents in this
 * file, allowing us to avoid a whole pile of corner cases around logging
 * blocks that have been removed from the tree.
 *
 * See LOG_INODE_ALL and related defines for a description of what inode_only
 * does.
 *
 * This handles both files and directories.
 */
static int btrfs_log_inode(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root, struct inode *inode,
			     int inode_only)
{
	struct btrfs_path *path;
	struct btrfs_path *dst_path;
	struct btrfs_key min_key;
	struct btrfs_key max_key;
	struct btrfs_root *log = root->log_root;
	struct extent_buffer *src = NULL;
	u32 size;
	int ret;
	int nritems;
	int ins_start_slot = 0;
	int ins_nr;

	log = root->log_root;

	path = btrfs_alloc_path();
	dst_path = btrfs_alloc_path();

	min_key.objectid = inode->i_ino;
	min_key.type = BTRFS_INODE_ITEM_KEY;
	min_key.offset = 0;

	max_key.objectid = inode->i_ino;

	/* today the code can only do partial logging of directories */
	if (!S_ISDIR(inode->i_mode))
	    inode_only = LOG_INODE_ALL;

	if (inode_only == LOG_INODE_EXISTS || S_ISDIR(inode->i_mode))
		max_key.type = BTRFS_XATTR_ITEM_KEY;
	else
		max_key.type = (u8)-1;
	max_key.offset = (u64)-1;

	mutex_lock(&BTRFS_I(inode)->log_mutex);

	/*
	 * a brute force approach to making sure we get the most uptodate
	 * copies of everything.
	 */
	if (S_ISDIR(inode->i_mode)) {
		int max_key_type = BTRFS_DIR_LOG_INDEX_KEY;

		if (inode_only == LOG_INODE_EXISTS)
			max_key_type = BTRFS_XATTR_ITEM_KEY;
		ret = drop_objectid_items(trans, log, path,
					  inode->i_ino, max_key_type);
	} else {
		ret = btrfs_truncate_inode_items(trans, log, inode, 0, 0);
	}
	BUG_ON(ret);
	path->keep_locks = 1;

	while (1) {
		ins_nr = 0;
		ret = btrfs_search_forward(root, &min_key, &max_key,
					   path, 0, trans->transid);
		if (ret != 0)
			break;
again:
		/* note, ins_nr might be > 0 here, cleanup outside the loop */
		if (min_key.objectid != inode->i_ino)
			break;
		if (min_key.type > max_key.type)
			break;

		src = path->nodes[0];
		size = btrfs_item_size_nr(src, path->slots[0]);
		if (ins_nr && ins_start_slot + ins_nr == path->slots[0]) {
			ins_nr++;
			goto next_slot;
		} else if (!ins_nr) {
			ins_start_slot = path->slots[0];
			ins_nr = 1;
			goto next_slot;
		}

		ret = copy_items(trans, log, dst_path, src, ins_start_slot,
				 ins_nr, inode_only);
		BUG_ON(ret);
		ins_nr = 1;
		ins_start_slot = path->slots[0];
next_slot:

		nritems = btrfs_header_nritems(path->nodes[0]);
		path->slots[0]++;
		if (path->slots[0] < nritems) {
			btrfs_item_key_to_cpu(path->nodes[0], &min_key,
					      path->slots[0]);
			goto again;
		}
		if (ins_nr) {
			ret = copy_items(trans, log, dst_path, src,
					 ins_start_slot,
					 ins_nr, inode_only);
			BUG_ON(ret);
			ins_nr = 0;
		}
		btrfs_release_path(root, path);

		if (min_key.offset < (u64)-1)
			min_key.offset++;
		else if (min_key.type < (u8)-1)
			min_key.type++;
		else if (min_key.objectid < (u64)-1)
			min_key.objectid++;
		else
			break;
	}
	if (ins_nr) {
		ret = copy_items(trans, log, dst_path, src,
				 ins_start_slot,
				 ins_nr, inode_only);
		BUG_ON(ret);
		ins_nr = 0;
	}
	WARN_ON(ins_nr);
	if (inode_only == LOG_INODE_ALL && S_ISDIR(inode->i_mode)) {
		btrfs_release_path(root, path);
		btrfs_release_path(log, dst_path);
		ret = log_directory_changes(trans, root, inode, path, dst_path);
		BUG_ON(ret);
	}
	BTRFS_I(inode)->logged_trans = trans->transid;
	mutex_unlock(&BTRFS_I(inode)->log_mutex);

	btrfs_free_path(path);
	btrfs_free_path(dst_path);
	return 0;
}

/*
 * follow the dentry parent pointers up the chain and see if any
 * of the directories in it require a full commit before they can
 * be logged.  Returns zero if nothing special needs to be done or 1 if
 * a full commit is required.
 */
static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
					       struct inode *inode,
					       struct dentry *parent,
					       struct super_block *sb,
					       u64 last_committed)
{
	int ret = 0;
	struct btrfs_root *root;

	/*
	 * for regular files, if its inode is already on disk, we don't
	 * have to worry about the parents at all.  This is because
	 * we can use the last_unlink_trans field to record renames
	 * and other fun in this file.
	 */
	if (S_ISREG(inode->i_mode) &&
	    BTRFS_I(inode)->generation <= last_committed &&
	    BTRFS_I(inode)->last_unlink_trans <= last_committed)
			goto out;

	if (!S_ISDIR(inode->i_mode)) {
		if (!parent || !parent->d_inode || sb != parent->d_inode->i_sb)
			goto out;
		inode = parent->d_inode;
	}

	while (1) {
		BTRFS_I(inode)->logged_trans = trans->transid;
		smp_mb();

		if (BTRFS_I(inode)->last_unlink_trans > last_committed) {
			root = BTRFS_I(inode)->root;

			/*
			 * make sure any commits to the log are forced
			 * to be full commits
			 */
			root->fs_info->last_trans_log_full_commit =
				trans->transid;
			ret = 1;
			break;
		}

		if (!parent || !parent->d_inode || sb != parent->d_inode->i_sb)
			break;

		if (IS_ROOT(parent))
			break;

		parent = parent->d_parent;
		inode = parent->d_inode;

	}
out:
	return ret;
}

static int inode_in_log(struct btrfs_trans_handle *trans,
		 struct inode *inode)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	int ret = 0;

	mutex_lock(&root->log_mutex);
	if (BTRFS_I(inode)->logged_trans == trans->transid &&
	    BTRFS_I(inode)->last_sub_trans <= root->last_log_commit)
		ret = 1;
	mutex_unlock(&root->log_mutex);
	return ret;
}


/*
 * helper function around btrfs_log_inode to make sure newly created
 * parent directories also end up in the log.  A minimal inode and backref
 * only logging is done of any parent directories that are older than
 * the last committed transaction
 */
int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
		    struct btrfs_root *root, struct inode *inode,
		    struct dentry *parent, int exists_only)
{
	int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
	struct super_block *sb;
	int ret = 0;
	u64 last_committed = root->fs_info->last_trans_committed;

	sb = inode->i_sb;

	if (btrfs_test_opt(root, NOTREELOG)) {
		ret = 1;
		goto end_no_trans;
	}

	if (root->fs_info->last_trans_log_full_commit >
	    root->fs_info->last_trans_committed) {
		ret = 1;
		goto end_no_trans;
	}

	if (root != BTRFS_I(inode)->root ||
	    btrfs_root_refs(&root->root_item) == 0) {
		ret = 1;
		goto end_no_trans;
	}

	ret = check_parent_dirs_for_sync(trans, inode, parent,
					 sb, last_committed);
	if (ret)
		goto end_no_trans;

	if (inode_in_log(trans, inode)) {
		ret = BTRFS_NO_LOG_SYNC;
		goto end_no_trans;
	}

	start_log_trans(trans, root);

	ret = btrfs_log_inode(trans, root, inode, inode_only);
	BUG_ON(ret);

	/*
	 * for regular files, if its inode is already on disk, we don't
	 * have to worry about the parents at all.  This is because
	 * we can use the last_unlink_trans field to record renames
	 * and other fun in this file.
	 */
	if (S_ISREG(inode->i_mode) &&
	    BTRFS_I(inode)->generation <= last_committed &&
	    BTRFS_I(inode)->last_unlink_trans <= last_committed)
			goto no_parent;

	inode_only = LOG_INODE_EXISTS;
	while (1) {
		if (!parent || !parent->d_inode || sb != parent->d_inode->i_sb)
			break;

		inode = parent->d_inode;
		if (root != BTRFS_I(inode)->root)
			break;

		if (BTRFS_I(inode)->generation >
		    root->fs_info->last_trans_committed) {
			ret = btrfs_log_inode(trans, root, inode, inode_only);
			BUG_ON(ret);
		}
		if (IS_ROOT(parent))
			break;

		parent = parent->d_parent;
	}
no_parent:
	ret = 0;
	btrfs_end_log_trans(root);
end_no_trans:
	return ret;
}

/*
 * it is not safe to log dentry if the chunk root has added new
 * chunks.  This returns 0 if the dentry was logged, and 1 otherwise.
 * If this returns 1, you must commit the transaction to safely get your
 * data on disk.
 */
int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
			  struct btrfs_root *root, struct dentry *dentry)
{
	return btrfs_log_inode_parent(trans, root, dentry->d_inode,
				      dentry->d_parent, 0);
}

/*
 * should be called during mount to recover any replay any log trees
 * from the FS
 */
int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_trans_handle *trans;
	struct btrfs_key key;
	struct btrfs_key found_key;
	struct btrfs_key tmp_key;
	struct btrfs_root *log;
	struct btrfs_fs_info *fs_info = log_root_tree->fs_info;
	struct walk_control wc = {
		.process_func = process_one_buffer,
		.stage = 0,
	};

	fs_info->log_root_recovering = 1;
	path = btrfs_alloc_path();
	BUG_ON(!path);

	trans = btrfs_start_transaction(fs_info->tree_root, 1);

	wc.trans = trans;
	wc.pin = 1;

	walk_log_tree(trans, log_root_tree, &wc);

again:
	key.objectid = BTRFS_TREE_LOG_OBJECTID;
	key.offset = (u64)-1;
	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);

	while (1) {
		ret = btrfs_search_slot(NULL, log_root_tree, &key, path, 0, 0);
		if (ret < 0)
			break;
		if (ret > 0) {
			if (path->slots[0] == 0)
				break;
			path->slots[0]--;
		}
		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
				      path->slots[0]);
		btrfs_release_path(log_root_tree, path);
		if (found_key.objectid != BTRFS_TREE_LOG_OBJECTID)
			break;

		log = btrfs_read_fs_root_no_radix(log_root_tree,
						  &found_key);
		BUG_ON(!log);


		tmp_key.objectid = found_key.offset;
		tmp_key.type = BTRFS_ROOT_ITEM_KEY;
		tmp_key.offset = (u64)-1;

		wc.replay_dest = btrfs_read_fs_root_no_name(fs_info, &tmp_key);
		BUG_ON(!wc.replay_dest);

		wc.replay_dest->log_root = log;
		btrfs_record_root_in_trans(trans, wc.replay_dest);
		ret = walk_log_tree(trans, log, &wc);
		BUG_ON(ret);

		if (wc.stage == LOG_WALK_REPLAY_ALL) {
			ret = fixup_inode_link_counts(trans, wc.replay_dest,
						      path);
			BUG_ON(ret);
		}

		key.offset = found_key.offset - 1;
		wc.replay_dest->log_root = NULL;
		free_extent_buffer(log->node);
		free_extent_buffer(log->commit_root);
		kfree(log);

		if (found_key.offset == 0)
			break;
	}
	btrfs_release_path(log_root_tree, path);

	/* step one is to pin it all, step two is to replay just inodes */
	if (wc.pin) {
		wc.pin = 0;
		wc.process_func = replay_one_buffer;
		wc.stage = LOG_WALK_REPLAY_INODES;
		goto again;
	}
	/* step three is to replay everything */
	if (wc.stage < LOG_WALK_REPLAY_ALL) {
		wc.stage++;
		goto again;
	}

	btrfs_free_path(path);

	free_extent_buffer(log_root_tree->node);
	log_root_tree->log_root = NULL;
	fs_info->log_root_recovering = 0;

	/* step 4: commit the transaction, which also unpins the blocks */
	btrfs_commit_transaction(trans, fs_info->tree_root);

	kfree(log_root_tree);
	return 0;
}

/*
 * there are some corner cases where we want to force a full
 * commit instead of allowing a directory to be logged.
 *
 * They revolve around files there were unlinked from the directory, and
 * this function updates the parent directory so that a full commit is
 * properly done if it is fsync'd later after the unlinks are done.
 */
void btrfs_record_unlink_dir(struct btrfs_trans_handle *trans,
			     struct inode *dir, struct inode *inode,
			     int for_rename)
{
	/*
	 * when we're logging a file, if it hasn't been renamed
	 * or unlinked, and its inode is fully committed on disk,
	 * we don't have to worry about walking up the directory chain
	 * to log its parents.
	 *
	 * So, we use the last_unlink_trans field to put this transid
	 * into the file.  When the file is logged we check it and
	 * don't log the parents if the file is fully on disk.
	 */
	if (S_ISREG(inode->i_mode))
		BTRFS_I(inode)->last_unlink_trans = trans->transid;

	/*
	 * if this directory was already logged any new
	 * names for this file/dir will get recorded
	 */
	smp_mb();
	if (BTRFS_I(dir)->logged_trans == trans->transid)
		return;

	/*
	 * if the inode we're about to unlink was logged,
	 * the log will be properly updated for any new names
	 */
	if (BTRFS_I(inode)->logged_trans == trans->transid)
		return;

	/*
	 * when renaming files across directories, if the directory
	 * there we're unlinking from gets fsync'd later on, there's
	 * no way to find the destination directory later and fsync it
	 * properly.  So, we have to be conservative and force commits
	 * so the new name gets discovered.
	 */
	if (for_rename)
		goto record;

	/* we can safely do the unlink without any special recording */
	return;

record:
	BTRFS_I(dir)->last_unlink_trans = trans->transid;
}

/*
 * Call this after adding a new name for a file and it will properly
 * update the log to reflect the new name.
 *
 * It will return zero if all goes well, and it will return 1 if a
 * full transaction commit is required.
 */
int btrfs_log_new_name(struct btrfs_trans_handle *trans,
			struct inode *inode, struct inode *old_dir,
			struct dentry *parent)
{
	struct btrfs_root * root = BTRFS_I(inode)->root;

	/*
	 * this will force the logging code to walk the dentry chain
	 * up for the file
	 */
	if (S_ISREG(inode->i_mode))
		BTRFS_I(inode)->last_unlink_trans = trans->transid;

	/*
	 * if this inode hasn't been logged and directory we're renaming it
	 * from hasn't been logged, we don't need to log it
	 */
	if (BTRFS_I(inode)->logged_trans <=
	    root->fs_info->last_trans_committed &&
	    (!old_dir || BTRFS_I(old_dir)->logged_trans <=
		    root->fs_info->last_trans_committed))
		return 0;

	return btrfs_log_inode_parent(trans, root, inode, parent, 1);
}