Bootlin logo

Elixir Cross Referencer

   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
/*
 * Implementation of the diskquota system for the LINUX operating system. QUOTA
 * is implemented using the BSD system call interface as the means of
 * communication with the user level. This file contains the generic routines
 * called by the different filesystems on allocation of an inode or block.
 * These routines take care of the administration needed to have a consistent
 * diskquota tracking system. The ideas of both user and group quotas are based
 * on the Melbourne quota system as used on BSD derived systems. The internal
 * implementation is based on one of the several variants of the LINUX
 * inode-subsystem with added complexity of the diskquota system.
 * 
 * Author:	Marco van Wieringen <mvw@planets.elm.net>
 *
 * Fixes:   Dmitry Gorodchanin <pgmdsg@ibi.com>, 11 Feb 96
 *
 *		Revised list management to avoid races
 *		-- Bill Hawes, <whawes@star.net>, 9/98
 *
 *		Fixed races in dquot_transfer(), dqget() and dquot_alloc_...().
 *		As the consequence the locking was moved from dquot_decr_...(),
 *		dquot_incr_...() to calling functions.
 *		invalidate_dquots() now writes modified dquots.
 *		Serialized quota_off() and quota_on() for mount point.
 *		Fixed a few bugs in grow_dquots().
 *		Fixed deadlock in write_dquot() - we no longer account quotas on
 *		quota files
 *		remove_dquot_ref() moved to inode.c - it now traverses through inodes
 *		add_dquot_ref() restarts after blocking
 *		Added check for bogus uid and fixed check for group in quotactl.
 *		Jan Kara, <jack@suse.cz>, sponsored by SuSE CR, 10-11/99
 *
 *		Used struct list_head instead of own list struct
 *		Invalidation of referenced dquots is no longer possible
 *		Improved free_dquots list management
 *		Quota and i_blocks are now updated in one place to avoid races
 *		Warnings are now delayed so we won't block in critical section
 *		Write updated not to require dquot lock
 *		Jan Kara, <jack@suse.cz>, 9/2000
 *
 *		Added dynamic quota structure allocation
 *		Jan Kara <jack@suse.cz> 12/2000
 *
 *		Rewritten quota interface. Implemented new quota format and
 *		formats registering.
 *		Jan Kara, <jack@suse.cz>, 2001,2002
 *
 *		New SMP locking.
 *		Jan Kara, <jack@suse.cz>, 10/2002
 *
 *		Added journalled quota support, fix lock inversion problems
 *		Jan Kara, <jack@suse.cz>, 2003,2004
 *
 * (C) Copyright 1994 - 1997 Marco van Wieringen 
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/mm.h>
#include <linux/time.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/tty.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/namei.h>
#include <linux/capability.h>
#include <linux/quotaops.h>
#include "../internal.h" /* ugh */

#include <linux/uaccess.h>

/*
 * There are three quota SMP locks. dq_list_lock protects all lists with quotas
 * and quota formats.
 * dq_data_lock protects data from dq_dqb and also mem_dqinfo structures and
 * also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes.
 * i_blocks and i_bytes updates itself are guarded by i_lock acquired directly
 * in inode_add_bytes() and inode_sub_bytes(). dq_state_lock protects
 * modifications of quota state (on quotaon and quotaoff) and readers who care
 * about latest values take it as well.
 *
 * The spinlock ordering is hence: dq_data_lock > dq_list_lock > i_lock,
 *   dq_list_lock > dq_state_lock
 *
 * Note that some things (eg. sb pointer, type, id) doesn't change during
 * the life of the dquot structure and so needn't to be protected by a lock
 *
 * Any operation working on dquots via inode pointers must hold dqptr_sem.  If
 * operation is just reading pointers from inode (or not using them at all) the
 * read lock is enough. If pointers are altered function must hold write lock.
 * Special care needs to be taken about S_NOQUOTA inode flag (marking that
 * inode is a quota file). Functions adding pointers from inode to dquots have
 * to check this flag under dqptr_sem and then (if S_NOQUOTA is not set) they
 * have to do all pointer modifications before dropping dqptr_sem. This makes
 * sure they cannot race with quotaon which first sets S_NOQUOTA flag and
 * then drops all pointers to dquots from an inode.
 *
 * Each dquot has its dq_lock mutex. Locked dquots might not be referenced
 * from inodes (dquot_alloc_space() and such don't check the dq_lock).
 * Currently dquot is locked only when it is being read to memory (or space for
 * it is being allocated) on the first dqget() and when it is being released on
 * the last dqput(). The allocation and release oparations are serialized by
 * the dq_lock and by checking the use count in dquot_release().  Write
 * operations on dquots don't hold dq_lock as they copy data under dq_data_lock
 * spinlock to internal buffers before writing.
 *
 * Lock ordering (including related VFS locks) is the following:
 *   dqonoff_mutex > i_mutex > journal_lock > dqptr_sem > dquot->dq_lock >
 *   dqio_mutex
 * dqonoff_mutex > i_mutex comes from dquot_quota_sync, dquot_enable, etc.
 * The lock ordering of dqptr_sem imposed by quota code is only dqonoff_sem >
 * dqptr_sem. But filesystem has to count with the fact that functions such as
 * dquot_alloc_space() acquire dqptr_sem and they usually have to be called
 * from inside a transaction to keep filesystem consistency after a crash. Also
 * filesystems usually want to do some IO on dquot from ->mark_dirty which is
 * called with dqptr_sem held.
 */

static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_list_lock);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_state_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_data_lock);
EXPORT_SYMBOL(dq_data_lock);

void __quota_error(struct super_block *sb, const char *func,
		   const char *fmt, ...)
{
	if (printk_ratelimit()) {
		va_list args;
		struct va_format vaf;

		va_start(args, fmt);

		vaf.fmt = fmt;
		vaf.va = &args;

		printk(KERN_ERR "Quota error (device %s): %s: %pV\n",
		       sb->s_id, func, &vaf);

		va_end(args);
	}
}
EXPORT_SYMBOL(__quota_error);

#if defined(CONFIG_QUOTA_DEBUG) || defined(CONFIG_PRINT_QUOTA_WARNING)
static char *quotatypes[] = INITQFNAMES;
#endif
static struct quota_format_type *quota_formats;	/* List of registered formats */
static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;

/* SLAB cache for dquot structures */
static struct kmem_cache *dquot_cachep;

int register_quota_format(struct quota_format_type *fmt)
{
	spin_lock(&dq_list_lock);
	fmt->qf_next = quota_formats;
	quota_formats = fmt;
	spin_unlock(&dq_list_lock);
	return 0;
}
EXPORT_SYMBOL(register_quota_format);

void unregister_quota_format(struct quota_format_type *fmt)
{
	struct quota_format_type **actqf;

	spin_lock(&dq_list_lock);
	for (actqf = &quota_formats; *actqf && *actqf != fmt;
	     actqf = &(*actqf)->qf_next)
		;
	if (*actqf)
		*actqf = (*actqf)->qf_next;
	spin_unlock(&dq_list_lock);
}
EXPORT_SYMBOL(unregister_quota_format);

static struct quota_format_type *find_quota_format(int id)
{
	struct quota_format_type *actqf;

	spin_lock(&dq_list_lock);
	for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id;
	     actqf = actqf->qf_next)
		;
	if (!actqf || !try_module_get(actqf->qf_owner)) {
		int qm;

		spin_unlock(&dq_list_lock);
		
		for (qm = 0; module_names[qm].qm_fmt_id &&
			     module_names[qm].qm_fmt_id != id; qm++)
			;
		if (!module_names[qm].qm_fmt_id ||
		    request_module(module_names[qm].qm_mod_name))
			return NULL;

		spin_lock(&dq_list_lock);
		for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id;
		     actqf = actqf->qf_next)
			;
		if (actqf && !try_module_get(actqf->qf_owner))
			actqf = NULL;
	}
	spin_unlock(&dq_list_lock);
	return actqf;
}

static void put_quota_format(struct quota_format_type *fmt)
{
	module_put(fmt->qf_owner);
}

/*
 * Dquot List Management:
 * The quota code uses three lists for dquot management: the inuse_list,
 * free_dquots, and dquot_hash[] array. A single dquot structure may be
 * on all three lists, depending on its current state.
 *
 * All dquots are placed to the end of inuse_list when first created, and this
 * list is used for invalidate operation, which must look at every dquot.
 *
 * Unused dquots (dq_count == 0) are added to the free_dquots list when freed,
 * and this list is searched whenever we need an available dquot.  Dquots are
 * removed from the list as soon as they are used again, and
 * dqstats.free_dquots gives the number of dquots on the list. When
 * dquot is invalidated it's completely released from memory.
 *
 * Dquots with a specific identity (device, type and id) are placed on
 * one of the dquot_hash[] hash chains. The provides an efficient search
 * mechanism to locate a specific dquot.
 */

static LIST_HEAD(inuse_list);
static LIST_HEAD(free_dquots);
static unsigned int dq_hash_bits, dq_hash_mask;
static struct hlist_head *dquot_hash;

struct dqstats dqstats;
EXPORT_SYMBOL(dqstats);

static qsize_t inode_get_rsv_space(struct inode *inode);
static void __dquot_initialize(struct inode *inode, int type);

static inline unsigned int
hashfn(const struct super_block *sb, struct kqid qid)
{
	unsigned int id = from_kqid(&init_user_ns, qid);
	int type = qid.type;
	unsigned long tmp;

	tmp = (((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type);
	return (tmp + (tmp >> dq_hash_bits)) & dq_hash_mask;
}

/*
 * Following list functions expect dq_list_lock to be held
 */
static inline void insert_dquot_hash(struct dquot *dquot)
{
	struct hlist_head *head;
	head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id);
	hlist_add_head(&dquot->dq_hash, head);
}

static inline void remove_dquot_hash(struct dquot *dquot)
{
	hlist_del_init(&dquot->dq_hash);
}

static struct dquot *find_dquot(unsigned int hashent, struct super_block *sb,
				struct kqid qid)
{
	struct hlist_node *node;
	struct dquot *dquot;

	hlist_for_each (node, dquot_hash+hashent) {
		dquot = hlist_entry(node, struct dquot, dq_hash);
		if (dquot->dq_sb == sb && qid_eq(dquot->dq_id, qid))
			return dquot;
	}
	return NULL;
}

/* Add a dquot to the tail of the free list */
static inline void put_dquot_last(struct dquot *dquot)
{
	list_add_tail(&dquot->dq_free, &free_dquots);
	dqstats_inc(DQST_FREE_DQUOTS);
}

static inline void remove_free_dquot(struct dquot *dquot)
{
	if (list_empty(&dquot->dq_free))
		return;
	list_del_init(&dquot->dq_free);
	dqstats_dec(DQST_FREE_DQUOTS);
}

static inline void put_inuse(struct dquot *dquot)
{
	/* We add to the back of inuse list so we don't have to restart
	 * when traversing this list and we block */
	list_add_tail(&dquot->dq_inuse, &inuse_list);
	dqstats_inc(DQST_ALLOC_DQUOTS);
}

static inline void remove_inuse(struct dquot *dquot)
{
	dqstats_dec(DQST_ALLOC_DQUOTS);
	list_del(&dquot->dq_inuse);
}
/*
 * End of list functions needing dq_list_lock
 */

static void wait_on_dquot(struct dquot *dquot)
{
	mutex_lock(&dquot->dq_lock);
	mutex_unlock(&dquot->dq_lock);
}

static inline int dquot_dirty(struct dquot *dquot)
{
	return test_bit(DQ_MOD_B, &dquot->dq_flags);
}

static inline int mark_dquot_dirty(struct dquot *dquot)
{
	return dquot->dq_sb->dq_op->mark_dirty(dquot);
}

/* Mark dquot dirty in atomic manner, and return it's old dirty flag state */
int dquot_mark_dquot_dirty(struct dquot *dquot)
{
	int ret = 1;

	/* If quota is dirty already, we don't have to acquire dq_list_lock */
	if (test_bit(DQ_MOD_B, &dquot->dq_flags))
		return 1;

	spin_lock(&dq_list_lock);
	if (!test_and_set_bit(DQ_MOD_B, &dquot->dq_flags)) {
		list_add(&dquot->dq_dirty, &sb_dqopt(dquot->dq_sb)->
				info[dquot->dq_id.type].dqi_dirty_list);
		ret = 0;
	}
	spin_unlock(&dq_list_lock);
	return ret;
}
EXPORT_SYMBOL(dquot_mark_dquot_dirty);

/* Dirtify all the dquots - this can block when journalling */
static inline int mark_all_dquot_dirty(struct dquot * const *dquot)
{
	int ret, err, cnt;

	ret = err = 0;
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (dquot[cnt])
			/* Even in case of error we have to continue */
			ret = mark_dquot_dirty(dquot[cnt]);
		if (!err)
			err = ret;
	}
	return err;
}

static inline void dqput_all(struct dquot **dquot)
{
	unsigned int cnt;

	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		dqput(dquot[cnt]);
}

/* This function needs dq_list_lock */
static inline int clear_dquot_dirty(struct dquot *dquot)
{
	if (!test_and_clear_bit(DQ_MOD_B, &dquot->dq_flags))
		return 0;
	list_del_init(&dquot->dq_dirty);
	return 1;
}

void mark_info_dirty(struct super_block *sb, int type)
{
	set_bit(DQF_INFO_DIRTY_B, &sb_dqopt(sb)->info[type].dqi_flags);
}
EXPORT_SYMBOL(mark_info_dirty);

/*
 *	Read dquot from disk and alloc space for it
 */

int dquot_acquire(struct dquot *dquot)
{
	int ret = 0, ret2 = 0;
	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

	mutex_lock(&dquot->dq_lock);
	mutex_lock(&dqopt->dqio_mutex);
	if (!test_bit(DQ_READ_B, &dquot->dq_flags))
		ret = dqopt->ops[dquot->dq_id.type]->read_dqblk(dquot);
	if (ret < 0)
		goto out_iolock;
	set_bit(DQ_READ_B, &dquot->dq_flags);
	/* Instantiate dquot if needed */
	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) {
		ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
		/* Write the info if needed */
		if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
			ret2 = dqopt->ops[dquot->dq_id.type]->write_file_info(
					dquot->dq_sb, dquot->dq_id.type);
		}
		if (ret < 0)
			goto out_iolock;
		if (ret2 < 0) {
			ret = ret2;
			goto out_iolock;
		}
	}
	set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
out_iolock:
	mutex_unlock(&dqopt->dqio_mutex);
	mutex_unlock(&dquot->dq_lock);
	return ret;
}
EXPORT_SYMBOL(dquot_acquire);

/*
 *	Write dquot to disk
 */
int dquot_commit(struct dquot *dquot)
{
	int ret = 0;
	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

	mutex_lock(&dqopt->dqio_mutex);
	spin_lock(&dq_list_lock);
	if (!clear_dquot_dirty(dquot)) {
		spin_unlock(&dq_list_lock);
		goto out_sem;
	}
	spin_unlock(&dq_list_lock);
	/* Inactive dquot can be only if there was error during read/init
	 * => we have better not writing it */
	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
		ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
	else
		ret = -EIO;
out_sem:
	mutex_unlock(&dqopt->dqio_mutex);
	return ret;
}
EXPORT_SYMBOL(dquot_commit);

/*
 *	Release dquot
 */
int dquot_release(struct dquot *dquot)
{
	int ret = 0, ret2 = 0;
	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

	mutex_lock(&dquot->dq_lock);
	/* Check whether we are not racing with some other dqget() */
	if (atomic_read(&dquot->dq_count) > 1)
		goto out_dqlock;
	mutex_lock(&dqopt->dqio_mutex);
	if (dqopt->ops[dquot->dq_id.type]->release_dqblk) {
		ret = dqopt->ops[dquot->dq_id.type]->release_dqblk(dquot);
		/* Write the info */
		if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
			ret2 = dqopt->ops[dquot->dq_id.type]->write_file_info(
						dquot->dq_sb, dquot->dq_id.type);
		}
		if (ret >= 0)
			ret = ret2;
	}
	clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
	mutex_unlock(&dqopt->dqio_mutex);
out_dqlock:
	mutex_unlock(&dquot->dq_lock);
	return ret;
}
EXPORT_SYMBOL(dquot_release);

void dquot_destroy(struct dquot *dquot)
{
	kmem_cache_free(dquot_cachep, dquot);
}
EXPORT_SYMBOL(dquot_destroy);

static inline void do_destroy_dquot(struct dquot *dquot)
{
	dquot->dq_sb->dq_op->destroy_dquot(dquot);
}

/* Invalidate all dquots on the list. Note that this function is called after
 * quota is disabled and pointers from inodes removed so there cannot be new
 * quota users. There can still be some users of quotas due to inodes being
 * just deleted or pruned by prune_icache() (those are not attached to any
 * list) or parallel quotactl call. We have to wait for such users.
 */
static void invalidate_dquots(struct super_block *sb, int type)
{
	struct dquot *dquot, *tmp;

restart:
	spin_lock(&dq_list_lock);
	list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) {
		if (dquot->dq_sb != sb)
			continue;
		if (dquot->dq_id.type != type)
			continue;
		/* Wait for dquot users */
		if (atomic_read(&dquot->dq_count)) {
			DEFINE_WAIT(wait);

			dqgrab(dquot);
			prepare_to_wait(&dquot->dq_wait_unused, &wait,
					TASK_UNINTERRUPTIBLE);
			spin_unlock(&dq_list_lock);
			/* Once dqput() wakes us up, we know it's time to free
			 * the dquot.
			 * IMPORTANT: we rely on the fact that there is always
			 * at most one process waiting for dquot to free.
			 * Otherwise dq_count would be > 1 and we would never
			 * wake up.
			 */
			if (atomic_read(&dquot->dq_count) > 1)
				schedule();
			finish_wait(&dquot->dq_wait_unused, &wait);
			dqput(dquot);
			/* At this moment dquot() need not exist (it could be
			 * reclaimed by prune_dqcache(). Hence we must
			 * restart. */
			goto restart;
		}
		/*
		 * Quota now has no users and it has been written on last
		 * dqput()
		 */
		remove_dquot_hash(dquot);
		remove_free_dquot(dquot);
		remove_inuse(dquot);
		do_destroy_dquot(dquot);
	}
	spin_unlock(&dq_list_lock);
}

/* Call callback for every active dquot on given filesystem */
int dquot_scan_active(struct super_block *sb,
		      int (*fn)(struct dquot *dquot, unsigned long priv),
		      unsigned long priv)
{
	struct dquot *dquot, *old_dquot = NULL;
	int ret = 0;

	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
	spin_lock(&dq_list_lock);
	list_for_each_entry(dquot, &inuse_list, dq_inuse) {
		if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
			continue;
		if (dquot->dq_sb != sb)
			continue;
		/* Now we have active dquot so we can just increase use count */
		atomic_inc(&dquot->dq_count);
		spin_unlock(&dq_list_lock);
		dqstats_inc(DQST_LOOKUPS);
		dqput(old_dquot);
		old_dquot = dquot;
		/*
		 * ->release_dquot() can be racing with us. Our reference
		 * protects us from new calls to it so just wait for any
		 * outstanding call and recheck the DQ_ACTIVE_B after that.
		 */
		wait_on_dquot(dquot);
		if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
			ret = fn(dquot, priv);
			if (ret < 0)
				goto out;
		}
		spin_lock(&dq_list_lock);
		/* We are safe to continue now because our dquot could not
		 * be moved out of the inuse list while we hold the reference */
	}
	spin_unlock(&dq_list_lock);
out:
	dqput(old_dquot);
	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
	return ret;
}
EXPORT_SYMBOL(dquot_scan_active);

/* Write all dquot structures to quota files */
int dquot_writeback_dquots(struct super_block *sb, int type)
{
	struct list_head *dirty;
	struct dquot *dquot;
	struct quota_info *dqopt = sb_dqopt(sb);
	int cnt;
	int err, ret = 0;

	mutex_lock(&dqopt->dqonoff_mutex);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (type != -1 && cnt != type)
			continue;
		if (!sb_has_quota_active(sb, cnt))
			continue;
		spin_lock(&dq_list_lock);
		dirty = &dqopt->info[cnt].dqi_dirty_list;
		while (!list_empty(dirty)) {
			dquot = list_first_entry(dirty, struct dquot,
						 dq_dirty);
			/* Dirty and inactive can be only bad dquot... */
			if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
				clear_dquot_dirty(dquot);
				continue;
			}
			/* Now we have active dquot from which someone is
 			 * holding reference so we can safely just increase
			 * use count */
			dqgrab(dquot);
			spin_unlock(&dq_list_lock);
			dqstats_inc(DQST_LOOKUPS);
			err = sb->dq_op->write_dquot(dquot);
			if (!ret && err)
				ret = err;
			dqput(dquot);
			spin_lock(&dq_list_lock);
		}
		spin_unlock(&dq_list_lock);
	}

	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		if ((cnt == type || type == -1) && sb_has_quota_active(sb, cnt)
		    && info_dirty(&dqopt->info[cnt]))
			sb->dq_op->write_info(sb, cnt);
	dqstats_inc(DQST_SYNCS);
	mutex_unlock(&dqopt->dqonoff_mutex);

	return ret;
}
EXPORT_SYMBOL(dquot_writeback_dquots);

/* Write all dquot structures to disk and make them visible from userspace */
int dquot_quota_sync(struct super_block *sb, int type)
{
	struct quota_info *dqopt = sb_dqopt(sb);
	int cnt;
	int ret;

	ret = dquot_writeback_dquots(sb, type);
	if (ret)
		return ret;
	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
		return 0;

	/* This is not very clever (and fast) but currently I don't know about
	 * any other simple way of getting quota data to disk and we must get
	 * them there for userspace to be visible... */
	if (sb->s_op->sync_fs)
		sb->s_op->sync_fs(sb, 1);
	sync_blockdev(sb->s_bdev);

	/*
	 * Now when everything is written we can discard the pagecache so
	 * that userspace sees the changes.
	 */
	mutex_lock(&dqopt->dqonoff_mutex);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (type != -1 && cnt != type)
			continue;
		if (!sb_has_quota_active(sb, cnt))
			continue;
		mutex_lock(&dqopt->files[cnt]->i_mutex);
		truncate_inode_pages(&dqopt->files[cnt]->i_data, 0);
		mutex_unlock(&dqopt->files[cnt]->i_mutex);
	}
	mutex_unlock(&dqopt->dqonoff_mutex);

	return 0;
}
EXPORT_SYMBOL(dquot_quota_sync);

static unsigned long
dqcache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
{
	struct list_head *head;
	struct dquot *dquot;
	unsigned long freed = 0;

	spin_lock(&dq_list_lock);
	head = free_dquots.prev;
	while (head != &free_dquots && sc->nr_to_scan) {
		dquot = list_entry(head, struct dquot, dq_free);
		remove_dquot_hash(dquot);
		remove_free_dquot(dquot);
		remove_inuse(dquot);
		do_destroy_dquot(dquot);
		sc->nr_to_scan--;
		freed++;
		head = free_dquots.prev;
	}
	spin_unlock(&dq_list_lock);
	return freed;
}

static unsigned long
dqcache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
{
	return vfs_pressure_ratio(
	percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS]));
}

static struct shrinker dqcache_shrinker = {
	.count_objects = dqcache_shrink_count,
	.scan_objects = dqcache_shrink_scan,
	.seeks = DEFAULT_SEEKS,
};

/*
 * Put reference to dquot
 * NOTE: If you change this function please check whether dqput_blocks() works right...
 */
void dqput(struct dquot *dquot)
{
	int ret;

	if (!dquot)
		return;
#ifdef CONFIG_QUOTA_DEBUG
	if (!atomic_read(&dquot->dq_count)) {
		quota_error(dquot->dq_sb, "trying to free free dquot of %s %d",
			    quotatypes[dquot->dq_id.type],
			    from_kqid(&init_user_ns, dquot->dq_id));
		BUG();
	}
#endif
	dqstats_inc(DQST_DROPS);
we_slept:
	spin_lock(&dq_list_lock);
	if (atomic_read(&dquot->dq_count) > 1) {
		/* We have more than one user... nothing to do */
		atomic_dec(&dquot->dq_count);
		/* Releasing dquot during quotaoff phase? */
		if (!sb_has_quota_active(dquot->dq_sb, dquot->dq_id.type) &&
		    atomic_read(&dquot->dq_count) == 1)
			wake_up(&dquot->dq_wait_unused);
		spin_unlock(&dq_list_lock);
		return;
	}
	/* Need to release dquot? */
	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && dquot_dirty(dquot)) {
		spin_unlock(&dq_list_lock);
		/* Commit dquot before releasing */
		ret = dquot->dq_sb->dq_op->write_dquot(dquot);
		if (ret < 0) {
			quota_error(dquot->dq_sb, "Can't write quota structure"
				    " (error %d). Quota may get out of sync!",
				    ret);
			/*
			 * We clear dirty bit anyway, so that we avoid
			 * infinite loop here
			 */
			spin_lock(&dq_list_lock);
			clear_dquot_dirty(dquot);
			spin_unlock(&dq_list_lock);
		}
		goto we_slept;
	}
	/* Clear flag in case dquot was inactive (something bad happened) */
	clear_dquot_dirty(dquot);
	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
		spin_unlock(&dq_list_lock);
		dquot->dq_sb->dq_op->release_dquot(dquot);
		goto we_slept;
	}
	atomic_dec(&dquot->dq_count);
#ifdef CONFIG_QUOTA_DEBUG
	/* sanity check */
	BUG_ON(!list_empty(&dquot->dq_free));
#endif
	put_dquot_last(dquot);
	spin_unlock(&dq_list_lock);
}
EXPORT_SYMBOL(dqput);

struct dquot *dquot_alloc(struct super_block *sb, int type)
{
	return kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
}
EXPORT_SYMBOL(dquot_alloc);

static struct dquot *get_empty_dquot(struct super_block *sb, int type)
{
	struct dquot *dquot;

	dquot = sb->dq_op->alloc_dquot(sb, type);
	if(!dquot)
		return NULL;

	mutex_init(&dquot->dq_lock);
	INIT_LIST_HEAD(&dquot->dq_free);
	INIT_LIST_HEAD(&dquot->dq_inuse);
	INIT_HLIST_NODE(&dquot->dq_hash);
	INIT_LIST_HEAD(&dquot->dq_dirty);
	init_waitqueue_head(&dquot->dq_wait_unused);
	dquot->dq_sb = sb;
	dquot->dq_id = make_kqid_invalid(type);
	atomic_set(&dquot->dq_count, 1);

	return dquot;
}

/*
 * Get reference to dquot
 *
 * Locking is slightly tricky here. We are guarded from parallel quotaoff()
 * destroying our dquot by:
 *   a) checking for quota flags under dq_list_lock and
 *   b) getting a reference to dquot before we release dq_list_lock
 */
struct dquot *dqget(struct super_block *sb, struct kqid qid)
{
	unsigned int hashent = hashfn(sb, qid);
	struct dquot *dquot = NULL, *empty = NULL;

        if (!sb_has_quota_active(sb, qid.type))
		return NULL;
we_slept:
	spin_lock(&dq_list_lock);
	spin_lock(&dq_state_lock);
	if (!sb_has_quota_active(sb, qid.type)) {
		spin_unlock(&dq_state_lock);
		spin_unlock(&dq_list_lock);
		goto out;
	}
	spin_unlock(&dq_state_lock);

	dquot = find_dquot(hashent, sb, qid);
	if (!dquot) {
		if (!empty) {
			spin_unlock(&dq_list_lock);
			empty = get_empty_dquot(sb, qid.type);
			if (!empty)
				schedule();	/* Try to wait for a moment... */
			goto we_slept;
		}
		dquot = empty;
		empty = NULL;
		dquot->dq_id = qid;
		/* all dquots go on the inuse_list */
		put_inuse(dquot);
		/* hash it first so it can be found */
		insert_dquot_hash(dquot);
		spin_unlock(&dq_list_lock);
		dqstats_inc(DQST_LOOKUPS);
	} else {
		if (!atomic_read(&dquot->dq_count))
			remove_free_dquot(dquot);
		atomic_inc(&dquot->dq_count);
		spin_unlock(&dq_list_lock);
		dqstats_inc(DQST_CACHE_HITS);
		dqstats_inc(DQST_LOOKUPS);
	}
	/* Wait for dq_lock - after this we know that either dquot_release() is
	 * already finished or it will be canceled due to dq_count > 1 test */
	wait_on_dquot(dquot);
	/* Read the dquot / allocate space in quota file */
	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) &&
	    sb->dq_op->acquire_dquot(dquot) < 0) {
		dqput(dquot);
		dquot = NULL;
		goto out;
	}
#ifdef CONFIG_QUOTA_DEBUG
	BUG_ON(!dquot->dq_sb);	/* Has somebody invalidated entry under us? */
#endif
out:
	if (empty)
		do_destroy_dquot(empty);

	return dquot;
}
EXPORT_SYMBOL(dqget);

static int dqinit_needed(struct inode *inode, int type)
{
	int cnt;

	if (IS_NOQUOTA(inode))
		return 0;
	if (type != -1)
		return !inode->i_dquot[type];
	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		if (!inode->i_dquot[cnt])
			return 1;
	return 0;
}

/* This routine is guarded by dqonoff_mutex mutex */
static void add_dquot_ref(struct super_block *sb, int type)
{
	struct inode *inode, *old_inode = NULL;
#ifdef CONFIG_QUOTA_DEBUG
	int reserved = 0;
#endif

	spin_lock(&inode_sb_list_lock);
	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
		spin_lock(&inode->i_lock);
		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
		    !atomic_read(&inode->i_writecount) ||
		    !dqinit_needed(inode, type)) {
			spin_unlock(&inode->i_lock);
			continue;
		}
		__iget(inode);
		spin_unlock(&inode->i_lock);
		spin_unlock(&inode_sb_list_lock);

#ifdef CONFIG_QUOTA_DEBUG
		if (unlikely(inode_get_rsv_space(inode) > 0))
			reserved = 1;
#endif
		iput(old_inode);
		__dquot_initialize(inode, type);

		/*
		 * We hold a reference to 'inode' so it couldn't have been
		 * removed from s_inodes list while we dropped the
		 * inode_sb_list_lock We cannot iput the inode now as we can be
		 * holding the last reference and we cannot iput it under
		 * inode_sb_list_lock. So we keep the reference and iput it
		 * later.
		 */
		old_inode = inode;
		spin_lock(&inode_sb_list_lock);
	}
	spin_unlock(&inode_sb_list_lock);
	iput(old_inode);

#ifdef CONFIG_QUOTA_DEBUG
	if (reserved) {
		quota_error(sb, "Writes happened before quota was turned on "
			"thus quota information is probably inconsistent. "
			"Please run quotacheck(8)");
	}
#endif
}

/*
 * Return 0 if dqput() won't block.
 * (note that 1 doesn't necessarily mean blocking)
 */
static inline int dqput_blocks(struct dquot *dquot)
{
	if (atomic_read(&dquot->dq_count) <= 1)
		return 1;
	return 0;
}

/*
 * Remove references to dquots from inode and add dquot to list for freeing
 * if we have the last reference to dquot
 * We can't race with anybody because we hold dqptr_sem for writing...
 */
static int remove_inode_dquot_ref(struct inode *inode, int type,
				  struct list_head *tofree_head)
{
	struct dquot *dquot = inode->i_dquot[type];

	inode->i_dquot[type] = NULL;
	if (dquot) {
		if (dqput_blocks(dquot)) {
#ifdef CONFIG_QUOTA_DEBUG
			if (atomic_read(&dquot->dq_count) != 1)
				quota_error(inode->i_sb, "Adding dquot with "
					    "dq_count %d to dispose list",
					    atomic_read(&dquot->dq_count));
#endif
			spin_lock(&dq_list_lock);
			/* As dquot must have currently users it can't be on
			 * the free list... */
			list_add(&dquot->dq_free, tofree_head);
			spin_unlock(&dq_list_lock);
			return 1;
		}
		else
			dqput(dquot);   /* We have guaranteed we won't block */
	}
	return 0;
}

/*
 * Free list of dquots
 * Dquots are removed from inodes and no new references can be got so we are
 * the only ones holding reference
 */
static void put_dquot_list(struct list_head *tofree_head)
{
	struct list_head *act_head;
	struct dquot *dquot;

	act_head = tofree_head->next;
	while (act_head != tofree_head) {
		dquot = list_entry(act_head, struct dquot, dq_free);
		act_head = act_head->next;
		/* Remove dquot from the list so we won't have problems... */
		list_del_init(&dquot->dq_free);
		dqput(dquot);
	}
}

static void remove_dquot_ref(struct super_block *sb, int type,
		struct list_head *tofree_head)
{
	struct inode *inode;
	int reserved = 0;

	spin_lock(&inode_sb_list_lock);
	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
		/*
		 *  We have to scan also I_NEW inodes because they can already
		 *  have quota pointer initialized. Luckily, we need to touch
		 *  only quota pointers and these have separate locking
		 *  (dqptr_sem).
		 */
		if (!IS_NOQUOTA(inode)) {
			if (unlikely(inode_get_rsv_space(inode) > 0))
				reserved = 1;
			remove_inode_dquot_ref(inode, type, tofree_head);
		}
	}
	spin_unlock(&inode_sb_list_lock);
#ifdef CONFIG_QUOTA_DEBUG
	if (reserved) {
		printk(KERN_WARNING "VFS (%s): Writes happened after quota"
			" was disabled thus quota information is probably "
			"inconsistent. Please run quotacheck(8).\n", sb->s_id);
	}
#endif
}

/* Gather all references from inodes and drop them */
static void drop_dquot_ref(struct super_block *sb, int type)
{
	LIST_HEAD(tofree_head);

	if (sb->dq_op) {
		down_write(&sb_dqopt(sb)->dqptr_sem);
		remove_dquot_ref(sb, type, &tofree_head);
		up_write(&sb_dqopt(sb)->dqptr_sem);
		put_dquot_list(&tofree_head);
	}
}

static inline void dquot_incr_inodes(struct dquot *dquot, qsize_t number)
{
	dquot->dq_dqb.dqb_curinodes += number;
}

static inline void dquot_incr_space(struct dquot *dquot, qsize_t number)
{
	dquot->dq_dqb.dqb_curspace += number;
}

static inline void dquot_resv_space(struct dquot *dquot, qsize_t number)
{
	dquot->dq_dqb.dqb_rsvspace += number;
}

/*
 * Claim reserved quota space
 */
static void dquot_claim_reserved_space(struct dquot *dquot, qsize_t number)
{
	if (dquot->dq_dqb.dqb_rsvspace < number) {
		WARN_ON_ONCE(1);
		number = dquot->dq_dqb.dqb_rsvspace;
	}
	dquot->dq_dqb.dqb_curspace += number;
	dquot->dq_dqb.dqb_rsvspace -= number;
}

static void dquot_reclaim_reserved_space(struct dquot *dquot, qsize_t number)
{
	if (WARN_ON_ONCE(dquot->dq_dqb.dqb_curspace < number))
		number = dquot->dq_dqb.dqb_curspace;
	dquot->dq_dqb.dqb_rsvspace += number;
	dquot->dq_dqb.dqb_curspace -= number;
}

static inline
void dquot_free_reserved_space(struct dquot *dquot, qsize_t number)
{
	if (dquot->dq_dqb.dqb_rsvspace >= number)
		dquot->dq_dqb.dqb_rsvspace -= number;
	else {
		WARN_ON_ONCE(1);
		dquot->dq_dqb.dqb_rsvspace = 0;
	}
}

static void dquot_decr_inodes(struct dquot *dquot, qsize_t number)
{
	if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
	    dquot->dq_dqb.dqb_curinodes >= number)
		dquot->dq_dqb.dqb_curinodes -= number;
	else
		dquot->dq_dqb.dqb_curinodes = 0;
	if (dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit)
		dquot->dq_dqb.dqb_itime = (time_t) 0;
	clear_bit(DQ_INODES_B, &dquot->dq_flags);
}

static void dquot_decr_space(struct dquot *dquot, qsize_t number)
{
	if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
	    dquot->dq_dqb.dqb_curspace >= number)
		dquot->dq_dqb.dqb_curspace -= number;
	else
		dquot->dq_dqb.dqb_curspace = 0;
	if (dquot->dq_dqb.dqb_curspace <= dquot->dq_dqb.dqb_bsoftlimit)
		dquot->dq_dqb.dqb_btime = (time_t) 0;
	clear_bit(DQ_BLKS_B, &dquot->dq_flags);
}

struct dquot_warn {
	struct super_block *w_sb;
	struct kqid w_dq_id;
	short w_type;
};

static int warning_issued(struct dquot *dquot, const int warntype)
{
	int flag = (warntype == QUOTA_NL_BHARDWARN ||
		warntype == QUOTA_NL_BSOFTLONGWARN) ? DQ_BLKS_B :
		((warntype == QUOTA_NL_IHARDWARN ||
		warntype == QUOTA_NL_ISOFTLONGWARN) ? DQ_INODES_B : 0);

	if (!flag)
		return 0;
	return test_and_set_bit(flag, &dquot->dq_flags);
}

#ifdef CONFIG_PRINT_QUOTA_WARNING
static int flag_print_warnings = 1;

static int need_print_warning(struct dquot_warn *warn)
{
	if (!flag_print_warnings)
		return 0;

	switch (warn->w_dq_id.type) {
		case USRQUOTA:
			return uid_eq(current_fsuid(), warn->w_dq_id.uid);
		case GRPQUOTA:
			return in_group_p(warn->w_dq_id.gid);
		case PRJQUOTA:	/* Never taken... Just make gcc happy */
			return 0;
	}
	return 0;
}

/* Print warning to user which exceeded quota */
static void print_warning(struct dquot_warn *warn)
{
	char *msg = NULL;
	struct tty_struct *tty;
	int warntype = warn->w_type;

	if (warntype == QUOTA_NL_IHARDBELOW ||
	    warntype == QUOTA_NL_ISOFTBELOW ||
	    warntype == QUOTA_NL_BHARDBELOW ||
	    warntype == QUOTA_NL_BSOFTBELOW || !need_print_warning(warn))
		return;

	tty = get_current_tty();
	if (!tty)
		return;
	tty_write_message(tty, warn->w_sb->s_id);
	if (warntype == QUOTA_NL_ISOFTWARN || warntype == QUOTA_NL_BSOFTWARN)
		tty_write_message(tty, ": warning, ");
	else
		tty_write_message(tty, ": write failed, ");
	tty_write_message(tty, quotatypes[warn->w_dq_id.type]);
	switch (warntype) {
		case QUOTA_NL_IHARDWARN:
			msg = " file limit reached.\r\n";
			break;
		case QUOTA_NL_ISOFTLONGWARN:
			msg = " file quota exceeded too long.\r\n";
			break;
		case QUOTA_NL_ISOFTWARN:
			msg = " file quota exceeded.\r\n";
			break;
		case QUOTA_NL_BHARDWARN:
			msg = " block limit reached.\r\n";
			break;
		case QUOTA_NL_BSOFTLONGWARN:
			msg = " block quota exceeded too long.\r\n";
			break;
		case QUOTA_NL_BSOFTWARN:
			msg = " block quota exceeded.\r\n";
			break;
	}
	tty_write_message(tty, msg);
	tty_kref_put(tty);
}
#endif

static void prepare_warning(struct dquot_warn *warn, struct dquot *dquot,
			    int warntype)
{
	if (warning_issued(dquot, warntype))
		return;
	warn->w_type = warntype;
	warn->w_sb = dquot->dq_sb;
	warn->w_dq_id = dquot->dq_id;
}

/*
 * Write warnings to the console and send warning messages over netlink.
 *
 * Note that this function can call into tty and networking code.
 */
static void flush_warnings(struct dquot_warn *warn)
{
	int i;

	for (i = 0; i < MAXQUOTAS; i++) {
		if (warn[i].w_type == QUOTA_NL_NOWARN)
			continue;
#ifdef CONFIG_PRINT_QUOTA_WARNING
		print_warning(&warn[i]);
#endif
		quota_send_warning(warn[i].w_dq_id,
				   warn[i].w_sb->s_dev, warn[i].w_type);
	}
}

static int ignore_hardlimit(struct dquot *dquot)
{
	struct mem_dqinfo *info = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_id.type];

	return capable(CAP_SYS_RESOURCE) &&
	       (info->dqi_format->qf_fmt_id != QFMT_VFS_OLD ||
		!(info->dqi_flags & V1_DQF_RSQUASH));
}

/* needs dq_data_lock */
static int check_idq(struct dquot *dquot, qsize_t inodes,
		     struct dquot_warn *warn)
{
	qsize_t newinodes = dquot->dq_dqb.dqb_curinodes + inodes;

	if (!sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_id.type) ||
	    test_bit(DQ_FAKE_B, &dquot->dq_flags))
		return 0;

	if (dquot->dq_dqb.dqb_ihardlimit &&
	    newinodes > dquot->dq_dqb.dqb_ihardlimit &&
            !ignore_hardlimit(dquot)) {
		prepare_warning(warn, dquot, QUOTA_NL_IHARDWARN);
		return -EDQUOT;
	}

	if (dquot->dq_dqb.dqb_isoftlimit &&
	    newinodes > dquot->dq_dqb.dqb_isoftlimit &&
	    dquot->dq_dqb.dqb_itime &&
	    get_seconds() >= dquot->dq_dqb.dqb_itime &&
            !ignore_hardlimit(dquot)) {
		prepare_warning(warn, dquot, QUOTA_NL_ISOFTLONGWARN);
		return -EDQUOT;
	}

	if (dquot->dq_dqb.dqb_isoftlimit &&
	    newinodes > dquot->dq_dqb.dqb_isoftlimit &&
	    dquot->dq_dqb.dqb_itime == 0) {
		prepare_warning(warn, dquot, QUOTA_NL_ISOFTWARN);
		dquot->dq_dqb.dqb_itime = get_seconds() +
		    sb_dqopt(dquot->dq_sb)->info[dquot->dq_id.type].dqi_igrace;
	}

	return 0;
}

/* needs dq_data_lock */
static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc,
		     struct dquot_warn *warn)
{
	qsize_t tspace;
	struct super_block *sb = dquot->dq_sb;

	if (!sb_has_quota_limits_enabled(sb, dquot->dq_id.type) ||
	    test_bit(DQ_FAKE_B, &dquot->dq_flags))
		return 0;

	tspace = dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace
		+ space;

	if (dquot->dq_dqb.dqb_bhardlimit &&
	    tspace > dquot->dq_dqb.dqb_bhardlimit &&
            !ignore_hardlimit(dquot)) {
		if (!prealloc)
			prepare_warning(warn, dquot, QUOTA_NL_BHARDWARN);
		return -EDQUOT;
	}

	if (dquot->dq_dqb.dqb_bsoftlimit &&
	    tspace > dquot->dq_dqb.dqb_bsoftlimit &&
	    dquot->dq_dqb.dqb_btime &&
	    get_seconds() >= dquot->dq_dqb.dqb_btime &&
            !ignore_hardlimit(dquot)) {
		if (!prealloc)
			prepare_warning(warn, dquot, QUOTA_NL_BSOFTLONGWARN);
		return -EDQUOT;
	}

	if (dquot->dq_dqb.dqb_bsoftlimit &&
	    tspace > dquot->dq_dqb.dqb_bsoftlimit &&
	    dquot->dq_dqb.dqb_btime == 0) {
		if (!prealloc) {
			prepare_warning(warn, dquot, QUOTA_NL_BSOFTWARN);
			dquot->dq_dqb.dqb_btime = get_seconds() +
			    sb_dqopt(sb)->info[dquot->dq_id.type].dqi_bgrace;
		}
		else
			/*
			 * We don't allow preallocation to exceed softlimit so exceeding will
			 * be always printed
			 */
			return -EDQUOT;
	}

	return 0;
}

static int info_idq_free(struct dquot *dquot, qsize_t inodes)
{
	qsize_t newinodes;

	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||
	    dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit ||
	    !sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_id.type))
		return QUOTA_NL_NOWARN;

	newinodes = dquot->dq_dqb.dqb_curinodes - inodes;
	if (newinodes <= dquot->dq_dqb.dqb_isoftlimit)
		return QUOTA_NL_ISOFTBELOW;
	if (dquot->dq_dqb.dqb_curinodes >= dquot->dq_dqb.dqb_ihardlimit &&
	    newinodes < dquot->dq_dqb.dqb_ihardlimit)
		return QUOTA_NL_IHARDBELOW;
	return QUOTA_NL_NOWARN;
}

static int info_bdq_free(struct dquot *dquot, qsize_t space)
{
	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||
	    dquot->dq_dqb.dqb_curspace <= dquot->dq_dqb.dqb_bsoftlimit)
		return QUOTA_NL_NOWARN;

	if (dquot->dq_dqb.dqb_curspace - space <= dquot->dq_dqb.dqb_bsoftlimit)
		return QUOTA_NL_BSOFTBELOW;
	if (dquot->dq_dqb.dqb_curspace >= dquot->dq_dqb.dqb_bhardlimit &&
	    dquot->dq_dqb.dqb_curspace - space < dquot->dq_dqb.dqb_bhardlimit)
		return QUOTA_NL_BHARDBELOW;
	return QUOTA_NL_NOWARN;
}

static int dquot_active(const struct inode *inode)
{
	struct super_block *sb = inode->i_sb;

	if (IS_NOQUOTA(inode))
		return 0;
	return sb_any_quota_loaded(sb) & ~sb_any_quota_suspended(sb);
}

/*
 * Initialize quota pointers in inode
 *
 * We do things in a bit complicated way but by that we avoid calling
 * dqget() and thus filesystem callbacks under dqptr_sem.
 *
 * It is better to call this function outside of any transaction as it
 * might need a lot of space in journal for dquot structure allocation.
 */
static void __dquot_initialize(struct inode *inode, int type)
{
	int cnt;
	struct dquot *got[MAXQUOTAS];
	struct super_block *sb = inode->i_sb;
	qsize_t rsv;

	/* First test before acquiring mutex - solves deadlocks when we
         * re-enter the quota code and are already holding the mutex */
	if (!dquot_active(inode))
		return;

	/* First get references to structures we might need. */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		struct kqid qid;
		got[cnt] = NULL;
		if (type != -1 && cnt != type)
			continue;
		switch (cnt) {
		case USRQUOTA:
			qid = make_kqid_uid(inode->i_uid);
			break;
		case GRPQUOTA:
			qid = make_kqid_gid(inode->i_gid);
			break;
		}
		got[cnt] = dqget(sb, qid);
	}

	down_write(&sb_dqopt(sb)->dqptr_sem);
	if (IS_NOQUOTA(inode))
		goto out_err;
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (type != -1 && cnt != type)
			continue;
		/* Avoid races with quotaoff() */
		if (!sb_has_quota_active(sb, cnt))
			continue;
		/* We could race with quotaon or dqget() could have failed */
		if (!got[cnt])
			continue;
		if (!inode->i_dquot[cnt]) {
			inode->i_dquot[cnt] = got[cnt];
			got[cnt] = NULL;
			/*
			 * Make quota reservation system happy if someone
			 * did a write before quota was turned on
			 */
			rsv = inode_get_rsv_space(inode);
			if (unlikely(rsv)) {
				spin_lock(&dq_data_lock);
				dquot_resv_space(inode->i_dquot[cnt], rsv);
				spin_unlock(&dq_data_lock);
			}
		}
	}
out_err:
	up_write(&sb_dqopt(sb)->dqptr_sem);
	/* Drop unused references */
	dqput_all(got);
}

void dquot_initialize(struct inode *inode)
{
	__dquot_initialize(inode, -1);
}
EXPORT_SYMBOL(dquot_initialize);

/*
 * 	Release all quotas referenced by inode
 */
static void __dquot_drop(struct inode *inode)
{
	int cnt;
	struct dquot *put[MAXQUOTAS];

	down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		put[cnt] = inode->i_dquot[cnt];
		inode->i_dquot[cnt] = NULL;
	}
	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
	dqput_all(put);
}

void dquot_drop(struct inode *inode)
{
	int cnt;

	if (IS_NOQUOTA(inode))
		return;

	/*
	 * Test before calling to rule out calls from proc and such
	 * where we are not allowed to block. Note that this is
	 * actually reliable test even without the lock - the caller
	 * must assure that nobody can come after the DQUOT_DROP and
	 * add quota pointers back anyway.
	 */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (inode->i_dquot[cnt])
			break;
	}

	if (cnt < MAXQUOTAS)
		__dquot_drop(inode);
}
EXPORT_SYMBOL(dquot_drop);

/*
 * inode_reserved_space is managed internally by quota, and protected by
 * i_lock similar to i_blocks+i_bytes.
 */
static qsize_t *inode_reserved_space(struct inode * inode)
{
	/* Filesystem must explicitly define it's own method in order to use
	 * quota reservation interface */
	BUG_ON(!inode->i_sb->dq_op->get_reserved_space);
	return inode->i_sb->dq_op->get_reserved_space(inode);
}

void inode_add_rsv_space(struct inode *inode, qsize_t number)
{
	spin_lock(&inode->i_lock);
	*inode_reserved_space(inode) += number;
	spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(inode_add_rsv_space);

void inode_claim_rsv_space(struct inode *inode, qsize_t number)
{
	spin_lock(&inode->i_lock);
	*inode_reserved_space(inode) -= number;
	__inode_add_bytes(inode, number);
	spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(inode_claim_rsv_space);

void inode_reclaim_rsv_space(struct inode *inode, qsize_t number)
{
	spin_lock(&inode->i_lock);
	*inode_reserved_space(inode) += number;
	__inode_sub_bytes(inode, number);
	spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(inode_reclaim_rsv_space);

void inode_sub_rsv_space(struct inode *inode, qsize_t number)
{
	spin_lock(&inode->i_lock);
	*inode_reserved_space(inode) -= number;
	spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(inode_sub_rsv_space);

static qsize_t inode_get_rsv_space(struct inode *inode)
{
	qsize_t ret;

	if (!inode->i_sb->dq_op->get_reserved_space)
		return 0;
	spin_lock(&inode->i_lock);
	ret = *inode_reserved_space(inode);
	spin_unlock(&inode->i_lock);
	return ret;
}

static void inode_incr_space(struct inode *inode, qsize_t number,
				int reserve)
{
	if (reserve)
		inode_add_rsv_space(inode, number);
	else
		inode_add_bytes(inode, number);
}

static void inode_decr_space(struct inode *inode, qsize_t number, int reserve)
{
	if (reserve)
		inode_sub_rsv_space(inode, number);
	else
		inode_sub_bytes(inode, number);
}

/*
 * This functions updates i_blocks+i_bytes fields and quota information
 * (together with appropriate checks).
 *
 * NOTE: We absolutely rely on the fact that caller dirties the inode
 * (usually helpers in quotaops.h care about this) and holds a handle for
 * the current transaction so that dquot write and inode write go into the
 * same transaction.
 */

/*
 * This operation can block, but only after everything is updated
 */
int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
{
	int cnt, ret = 0;
	struct dquot_warn warn[MAXQUOTAS];
	struct dquot **dquots = inode->i_dquot;
	int reserve = flags & DQUOT_SPACE_RESERVE;

	/*
	 * First test before acquiring mutex - solves deadlocks when we
	 * re-enter the quota code and are already holding the mutex
	 */
	if (!dquot_active(inode)) {
		inode_incr_space(inode, number, reserve);
		goto out;
	}

	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		warn[cnt].w_type = QUOTA_NL_NOWARN;

	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	spin_lock(&dq_data_lock);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (!dquots[cnt])
			continue;
		ret = check_bdq(dquots[cnt], number,
				!(flags & DQUOT_SPACE_WARN), &warn[cnt]);
		if (ret && !(flags & DQUOT_SPACE_NOFAIL)) {
			spin_unlock(&dq_data_lock);
			goto out_flush_warn;
		}
	}
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (!dquots[cnt])
			continue;
		if (reserve)
			dquot_resv_space(dquots[cnt], number);
		else
			dquot_incr_space(dquots[cnt], number);
	}
	inode_incr_space(inode, number, reserve);
	spin_unlock(&dq_data_lock);

	if (reserve)
		goto out_flush_warn;
	mark_all_dquot_dirty(dquots);
out_flush_warn:
	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	flush_warnings(warn);
out:
	return ret;
}
EXPORT_SYMBOL(__dquot_alloc_space);

/*
 * This operation can block, but only after everything is updated
 */
int dquot_alloc_inode(const struct inode *inode)
{
	int cnt, ret = 0;
	struct dquot_warn warn[MAXQUOTAS];
	struct dquot * const *dquots = inode->i_dquot;

	/* First test before acquiring mutex - solves deadlocks when we
         * re-enter the quota code and are already holding the mutex */
	if (!dquot_active(inode))
		return 0;
	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		warn[cnt].w_type = QUOTA_NL_NOWARN;
	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	spin_lock(&dq_data_lock);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (!dquots[cnt])
			continue;
		ret = check_idq(dquots[cnt], 1, &warn[cnt]);
		if (ret)
			goto warn_put_all;
	}

	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (!dquots[cnt])
			continue;
		dquot_incr_inodes(dquots[cnt], 1);
	}

warn_put_all:
	spin_unlock(&dq_data_lock);
	if (ret == 0)
		mark_all_dquot_dirty(dquots);
	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	flush_warnings(warn);
	return ret;
}
EXPORT_SYMBOL(dquot_alloc_inode);

/*
 * Convert in-memory reserved quotas to real consumed quotas
 */
int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
{
	int cnt;

	if (!dquot_active(inode)) {
		inode_claim_rsv_space(inode, number);
		return 0;
	}

	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	spin_lock(&dq_data_lock);
	/* Claim reserved quotas to allocated quotas */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (inode->i_dquot[cnt])
			dquot_claim_reserved_space(inode->i_dquot[cnt],
							number);
	}
	/* Update inode bytes */
	inode_claim_rsv_space(inode, number);
	spin_unlock(&dq_data_lock);
	mark_all_dquot_dirty(inode->i_dquot);
	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	return 0;
}
EXPORT_SYMBOL(dquot_claim_space_nodirty);

/*
 * Convert allocated space back to in-memory reserved quotas
 */
void dquot_reclaim_space_nodirty(struct inode *inode, qsize_t number)
{
	int cnt;

	if (!dquot_active(inode)) {
		inode_reclaim_rsv_space(inode, number);
		return;
	}

	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	spin_lock(&dq_data_lock);
	/* Claim reserved quotas to allocated quotas */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (inode->i_dquot[cnt])
			dquot_reclaim_reserved_space(inode->i_dquot[cnt],
						     number);
	}
	/* Update inode bytes */
	inode_reclaim_rsv_space(inode, number);
	spin_unlock(&dq_data_lock);
	mark_all_dquot_dirty(inode->i_dquot);
	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	return;
}
EXPORT_SYMBOL(dquot_reclaim_space_nodirty);

/*
 * This operation can block, but only after everything is updated
 */
void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
{
	unsigned int cnt;
	struct dquot_warn warn[MAXQUOTAS];
	struct dquot **dquots = inode->i_dquot;
	int reserve = flags & DQUOT_SPACE_RESERVE;

	/* First test before acquiring mutex - solves deadlocks when we
         * re-enter the quota code and are already holding the mutex */
	if (!dquot_active(inode)) {
		inode_decr_space(inode, number, reserve);
		return;
	}

	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	spin_lock(&dq_data_lock);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		int wtype;

		warn[cnt].w_type = QUOTA_NL_NOWARN;
		if (!dquots[cnt])
			continue;
		wtype = info_bdq_free(dquots[cnt], number);
		if (wtype != QUOTA_NL_NOWARN)
			prepare_warning(&warn[cnt], dquots[cnt], wtype);
		if (reserve)
			dquot_free_reserved_space(dquots[cnt], number);
		else
			dquot_decr_space(dquots[cnt], number);
	}
	inode_decr_space(inode, number, reserve);
	spin_unlock(&dq_data_lock);

	if (reserve)
		goto out_unlock;
	mark_all_dquot_dirty(dquots);
out_unlock:
	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	flush_warnings(warn);
}
EXPORT_SYMBOL(__dquot_free_space);

/*
 * This operation can block, but only after everything is updated
 */
void dquot_free_inode(const struct inode *inode)
{
	unsigned int cnt;
	struct dquot_warn warn[MAXQUOTAS];
	struct dquot * const *dquots = inode->i_dquot;

	/* First test before acquiring mutex - solves deadlocks when we
         * re-enter the quota code and are already holding the mutex */
	if (!dquot_active(inode))
		return;

	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	spin_lock(&dq_data_lock);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		int wtype;

		warn[cnt].w_type = QUOTA_NL_NOWARN;
		if (!dquots[cnt])
			continue;
		wtype = info_idq_free(dquots[cnt], 1);
		if (wtype != QUOTA_NL_NOWARN)
			prepare_warning(&warn[cnt], dquots[cnt], wtype);
		dquot_decr_inodes(dquots[cnt], 1);
	}
	spin_unlock(&dq_data_lock);
	mark_all_dquot_dirty(dquots);
	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
	flush_warnings(warn);
}
EXPORT_SYMBOL(dquot_free_inode);

/*
 * Transfer the number of inode and blocks from one diskquota to an other.
 * On success, dquot references in transfer_to are consumed and references
 * to original dquots that need to be released are placed there. On failure,
 * references are kept untouched.
 *
 * This operation can block, but only after everything is updated
 * A transaction must be started when entering this function.
 *
 */
int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
{
	qsize_t space, cur_space;
	qsize_t rsv_space = 0;
	struct dquot *transfer_from[MAXQUOTAS] = {};
	int cnt, ret = 0;
	char is_valid[MAXQUOTAS] = {};
	struct dquot_warn warn_to[MAXQUOTAS];
	struct dquot_warn warn_from_inodes[MAXQUOTAS];
	struct dquot_warn warn_from_space[MAXQUOTAS];

	/* First test before acquiring mutex - solves deadlocks when we
         * re-enter the quota code and are already holding the mutex */
	if (IS_NOQUOTA(inode))
		return 0;
	/* Initialize the arrays */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		warn_to[cnt].w_type = QUOTA_NL_NOWARN;
		warn_from_inodes[cnt].w_type = QUOTA_NL_NOWARN;
		warn_from_space[cnt].w_type = QUOTA_NL_NOWARN;
	}
	down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
	if (IS_NOQUOTA(inode)) {	/* File without quota accounting? */
		up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
		return 0;
	}
	spin_lock(&dq_data_lock);
	cur_space = inode_get_bytes(inode);
	rsv_space = inode_get_rsv_space(inode);
	space = cur_space + rsv_space;
	/* Build the transfer_from list and check the limits */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		/*
		 * Skip changes for same uid or gid or for turned off quota-type.
		 */
		if (!transfer_to[cnt])
			continue;
		/* Avoid races with quotaoff() */
		if (!sb_has_quota_active(inode->i_sb, cnt))
			continue;
		is_valid[cnt] = 1;
		transfer_from[cnt] = inode->i_dquot[cnt];
		ret = check_idq(transfer_to[cnt], 1, &warn_to[cnt]);
		if (ret)
			goto over_quota;
		ret = check_bdq(transfer_to[cnt], space, 0, &warn_to[cnt]);
		if (ret)
			goto over_quota;
	}

	/*
	 * Finally perform the needed transfer from transfer_from to transfer_to
	 */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (!is_valid[cnt])
			continue;
		/* Due to IO error we might not have transfer_from[] structure */
		if (transfer_from[cnt]) {
			int wtype;
			wtype = info_idq_free(transfer_from[cnt], 1);
			if (wtype != QUOTA_NL_NOWARN)
				prepare_warning(&warn_from_inodes[cnt],
						transfer_from[cnt], wtype);
			wtype = info_bdq_free(transfer_from[cnt], space);
			if (wtype != QUOTA_NL_NOWARN)
				prepare_warning(&warn_from_space[cnt],
						transfer_from[cnt], wtype);
			dquot_decr_inodes(transfer_from[cnt], 1);
			dquot_decr_space(transfer_from[cnt], cur_space);
			dquot_free_reserved_space(transfer_from[cnt],
						  rsv_space);
		}

		dquot_incr_inodes(transfer_to[cnt], 1);
		dquot_incr_space(transfer_to[cnt], cur_space);
		dquot_resv_space(transfer_to[cnt], rsv_space);

		inode->i_dquot[cnt] = transfer_to[cnt];
	}
	spin_unlock(&dq_data_lock);
	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);

	mark_all_dquot_dirty(transfer_from);
	mark_all_dquot_dirty(transfer_to);
	flush_warnings(warn_to);
	flush_warnings(warn_from_inodes);
	flush_warnings(warn_from_space);
	/* Pass back references to put */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		if (is_valid[cnt])
			transfer_to[cnt] = transfer_from[cnt];
	return 0;
over_quota:
	spin_unlock(&dq_data_lock);
	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
	flush_warnings(warn_to);
	return ret;
}
EXPORT_SYMBOL(__dquot_transfer);

/* Wrapper for transferring ownership of an inode for uid/gid only
 * Called from FSXXX_setattr()
 */
int dquot_transfer(struct inode *inode, struct iattr *iattr)
{
	struct dquot *transfer_to[MAXQUOTAS] = {};
	struct super_block *sb = inode->i_sb;
	int ret;

	if (!dquot_active(inode))
		return 0;

	if (iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid))
		transfer_to[USRQUOTA] = dqget(sb, make_kqid_uid(iattr->ia_uid));
	if (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))
		transfer_to[GRPQUOTA] = dqget(sb, make_kqid_gid(iattr->ia_gid));

	ret = __dquot_transfer(inode, transfer_to);
	dqput_all(transfer_to);
	return ret;
}
EXPORT_SYMBOL(dquot_transfer);

/*
 * Write info of quota file to disk
 */
int dquot_commit_info(struct super_block *sb, int type)
{
	int ret;
	struct quota_info *dqopt = sb_dqopt(sb);

	mutex_lock(&dqopt->dqio_mutex);
	ret = dqopt->ops[type]->write_file_info(sb, type);
	mutex_unlock(&dqopt->dqio_mutex);
	return ret;
}
EXPORT_SYMBOL(dquot_commit_info);

/*
 * Definitions of diskquota operations.
 */
const struct dquot_operations dquot_operations = {
	.write_dquot	= dquot_commit,
	.acquire_dquot	= dquot_acquire,
	.release_dquot	= dquot_release,
	.mark_dirty	= dquot_mark_dquot_dirty,
	.write_info	= dquot_commit_info,
	.alloc_dquot	= dquot_alloc,
	.destroy_dquot	= dquot_destroy,
};
EXPORT_SYMBOL(dquot_operations);

/*
 * Generic helper for ->open on filesystems supporting disk quotas.
 */
int dquot_file_open(struct inode *inode, struct file *file)
{
	int error;

	error = generic_file_open(inode, file);
	if (!error && (file->f_mode & FMODE_WRITE))
		dquot_initialize(inode);
	return error;
}
EXPORT_SYMBOL(dquot_file_open);

/*
 * Turn quota off on a device. type == -1 ==> quotaoff for all types (umount)
 */
int dquot_disable(struct super_block *sb, int type, unsigned int flags)
{
	int cnt, ret = 0;
	struct quota_info *dqopt = sb_dqopt(sb);
	struct inode *toputinode[MAXQUOTAS];

	/* Cannot turn off usage accounting without turning off limits, or
	 * suspend quotas and simultaneously turn quotas off. */
	if ((flags & DQUOT_USAGE_ENABLED && !(flags & DQUOT_LIMITS_ENABLED))
	    || (flags & DQUOT_SUSPENDED && flags & (DQUOT_LIMITS_ENABLED |
	    DQUOT_USAGE_ENABLED)))
		return -EINVAL;

	/* We need to serialize quota_off() for device */
	mutex_lock(&dqopt->dqonoff_mutex);

	/*
	 * Skip everything if there's nothing to do. We have to do this because
	 * sometimes we are called when fill_super() failed and calling
	 * sync_fs() in such cases does no good.
	 */
	if (!sb_any_quota_loaded(sb)) {
		mutex_unlock(&dqopt->dqonoff_mutex);
		return 0;
	}
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		toputinode[cnt] = NULL;
		if (type != -1 && cnt != type)
			continue;
		if (!sb_has_quota_loaded(sb, cnt))
			continue;

		if (flags & DQUOT_SUSPENDED) {
			spin_lock(&dq_state_lock);
			dqopt->flags |=
				dquot_state_flag(DQUOT_SUSPENDED, cnt);
			spin_unlock(&dq_state_lock);
		} else {
			spin_lock(&dq_state_lock);
			dqopt->flags &= ~dquot_state_flag(flags, cnt);
			/* Turning off suspended quotas? */
			if (!sb_has_quota_loaded(sb, cnt) &&
			    sb_has_quota_suspended(sb, cnt)) {
				dqopt->flags &=	~dquot_state_flag(
							DQUOT_SUSPENDED, cnt);
				spin_unlock(&dq_state_lock);
				iput(dqopt->files[cnt]);
				dqopt->files[cnt] = NULL;
				continue;
			}
			spin_unlock(&dq_state_lock);
		}

		/* We still have to keep quota loaded? */
		if (sb_has_quota_loaded(sb, cnt) && !(flags & DQUOT_SUSPENDED))
			continue;

		/* Note: these are blocking operations */
		drop_dquot_ref(sb, cnt);
		invalidate_dquots(sb, cnt);
		/*
		 * Now all dquots should be invalidated, all writes done so we
		 * should be only users of the info. No locks needed.
		 */
		if (info_dirty(&dqopt->info[cnt]))
			sb->dq_op->write_info(sb, cnt);
		if (dqopt->ops[cnt]->free_file_info)
			dqopt->ops[cnt]->free_file_info(sb, cnt);
		put_quota_format(dqopt->info[cnt].dqi_format);

		toputinode[cnt] = dqopt->files[cnt];
		if (!sb_has_quota_loaded(sb, cnt))
			dqopt->files[cnt] = NULL;
		dqopt->info[cnt].dqi_flags = 0;
		dqopt->info[cnt].dqi_igrace = 0;
		dqopt->info[cnt].dqi_bgrace = 0;
		dqopt->ops[cnt] = NULL;
	}
	mutex_unlock(&dqopt->dqonoff_mutex);

	/* Skip syncing and setting flags if quota files are hidden */
	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
		goto put_inodes;

	/* Sync the superblock so that buffers with quota data are written to
	 * disk (and so userspace sees correct data afterwards). */
	if (sb->s_op->sync_fs)
		sb->s_op->sync_fs(sb, 1);
	sync_blockdev(sb->s_bdev);
	/* Now the quota files are just ordinary files and we can set the
	 * inode flags back. Moreover we discard the pagecache so that
	 * userspace sees the writes we did bypassing the pagecache. We
	 * must also discard the blockdev buffers so that we see the
	 * changes done by userspace on the next quotaon() */
	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		if (toputinode[cnt]) {
			mutex_lock(&dqopt->dqonoff_mutex);
			/* If quota was reenabled in the meantime, we have
			 * nothing to do */
			if (!sb_has_quota_loaded(sb, cnt)) {
				mutex_lock(&toputinode[cnt]->i_mutex);
				toputinode[cnt]->i_flags &= ~(S_IMMUTABLE |
				  S_NOATIME | S_NOQUOTA);
				truncate_inode_pages(&toputinode[cnt]->i_data,
						     0);
				mutex_unlock(&toputinode[cnt]->i_mutex);
				mark_inode_dirty_sync(toputinode[cnt]);
			}
			mutex_unlock(&dqopt->dqonoff_mutex);
		}
	if (sb->s_bdev)
		invalidate_bdev(sb->s_bdev);
put_inodes:
	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
		if (toputinode[cnt]) {
			/* On remount RO, we keep the inode pointer so that we
			 * can reenable quota on the subsequent remount RW. We
			 * have to check 'flags' variable and not use sb_has_
			 * function because another quotaon / quotaoff could
			 * change global state before we got here. We refuse
			 * to suspend quotas when there is pending delete on
			 * the quota file... */
			if (!(flags & DQUOT_SUSPENDED))
				iput(toputinode[cnt]);
			else if (!toputinode[cnt]->i_nlink)
				ret = -EBUSY;
		}
	return ret;
}
EXPORT_SYMBOL(dquot_disable);

int dquot_quota_off(struct super_block *sb, int type)
{
	return dquot_disable(sb, type,
			     DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
}
EXPORT_SYMBOL(dquot_quota_off);

/*
 *	Turn quotas on on a device
 */

/*
 * Helper function to turn quotas on when we already have the inode of
 * quota file and no quota information is loaded.
 */
static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
	unsigned int flags)
{
	struct quota_format_type *fmt = find_quota_format(format_id);
	struct super_block *sb = inode->i_sb;
	struct quota_info *dqopt = sb_dqopt(sb);
	int error;
	int oldflags = -1;

	if (!fmt)
		return -ESRCH;
	if (!S_ISREG(inode->i_mode)) {
		error = -EACCES;
		goto out_fmt;
	}
	if (IS_RDONLY(inode)) {
		error = -EROFS;
		goto out_fmt;
	}
	if (!sb->s_op->quota_write || !sb->s_op->quota_read) {
		error = -EINVAL;
		goto out_fmt;
	}
	/* Usage always has to be set... */
	if (!(flags & DQUOT_USAGE_ENABLED)) {
		error = -EINVAL;
		goto out_fmt;
	}

	if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
		/* As we bypass the pagecache we must now flush all the
		 * dirty data and invalidate caches so that kernel sees
		 * changes from userspace. It is not enough to just flush
		 * the quota file since if blocksize < pagesize, invalidation
		 * of the cache could fail because of other unrelated dirty
		 * data */
		sync_filesystem(sb);
		invalidate_bdev(sb->s_bdev);
	}
	mutex_lock(&dqopt->dqonoff_mutex);
	if (sb_has_quota_loaded(sb, type)) {
		error = -EBUSY;
		goto out_lock;
	}

	if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
		/* We don't want quota and atime on quota files (deadlocks
		 * possible) Also nobody should write to the file - we use
		 * special IO operations which ignore the immutable bit. */
		mutex_lock(&inode->i_mutex);
		oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE |
					     S_NOQUOTA);
		inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE;
		mutex_unlock(&inode->i_mutex);
		/*
		 * When S_NOQUOTA is set, remove dquot references as no more
		 * references can be added
		 */
		__dquot_drop(inode);
	}

	error = -EIO;
	dqopt->files[type] = igrab(inode);
	if (!dqopt->files[type])
		goto out_lock;
	error = -EINVAL;
	if (!fmt->qf_ops->check_quota_file(sb, type))
		goto out_file_init;

	dqopt->ops[type] = fmt->qf_ops;
	dqopt->info[type].dqi_format = fmt;
	dqopt->info[type].dqi_fmt_id = format_id;
	INIT_LIST_HEAD(&dqopt->info[type].dqi_dirty_list);
	mutex_lock(&dqopt->dqio_mutex);
	error = dqopt->ops[type]->read_file_info(sb, type);
	if (error < 0) {
		mutex_unlock(&dqopt->dqio_mutex);
		goto out_file_init;
	}
	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
		dqopt->info[type].dqi_flags |= DQF_SYS_FILE;
	mutex_unlock(&dqopt->dqio_mutex);
	spin_lock(&dq_state_lock);
	dqopt->flags |= dquot_state_flag(flags, type);
	spin_unlock(&dq_state_lock);

	add_dquot_ref(sb, type);
	mutex_unlock(&dqopt->dqonoff_mutex);

	return 0;

out_file_init:
	dqopt->files[type] = NULL;
	iput(inode);
out_lock:
	if (oldflags != -1) {
		mutex_lock(&inode->i_mutex);
		/* Set the flags back (in the case of accidental quotaon()
		 * on a wrong file we don't want to mess up the flags) */
		inode->i_flags &= ~(S_NOATIME | S_NOQUOTA | S_IMMUTABLE);
		inode->i_flags |= oldflags;
		mutex_unlock(&inode->i_mutex);
	}
	mutex_unlock(&dqopt->dqonoff_mutex);
out_fmt:
	put_quota_format(fmt);

	return error; 
}

/* Reenable quotas on remount RW */
int dquot_resume(struct super_block *sb, int type)
{
	struct quota_info *dqopt = sb_dqopt(sb);
	struct inode *inode;
	int ret = 0, cnt;
	unsigned int flags;

	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (type != -1 && cnt != type)
			continue;

		mutex_lock(&dqopt->dqonoff_mutex);
		if (!sb_has_quota_suspended(sb, cnt)) {
			mutex_unlock(&dqopt->dqonoff_mutex);
			continue;
		}
		inode = dqopt->files[cnt];
		dqopt->files[cnt] = NULL;
		spin_lock(&dq_state_lock);
		flags = dqopt->flags & dquot_state_flag(DQUOT_USAGE_ENABLED |
							DQUOT_LIMITS_ENABLED,
							cnt);
		dqopt->flags &= ~dquot_state_flag(DQUOT_STATE_FLAGS, cnt);
		spin_unlock(&dq_state_lock);
		mutex_unlock(&dqopt->dqonoff_mutex);

		flags = dquot_generic_flag(flags, cnt);
		ret = vfs_load_quota_inode(inode, cnt,
				dqopt->info[cnt].dqi_fmt_id, flags);
		iput(inode);
	}

	return ret;
}
EXPORT_SYMBOL(dquot_resume);

int dquot_quota_on(struct super_block *sb, int type, int format_id,
		   struct path *path)
{
	int error = security_quota_on(path->dentry);
	if (error)
		return error;
	/* Quota file not on the same filesystem? */
	if (path->dentry->d_sb != sb)
		error = -EXDEV;
	else
		error = vfs_load_quota_inode(path->dentry->d_inode, type,
					     format_id, DQUOT_USAGE_ENABLED |
					     DQUOT_LIMITS_ENABLED);
	return error;
}
EXPORT_SYMBOL(dquot_quota_on);

/*
 * More powerful function for turning on quotas allowing setting
 * of individual quota flags
 */
int dquot_enable(struct inode *inode, int type, int format_id,
		 unsigned int flags)
{
	int ret = 0;
	struct super_block *sb = inode->i_sb;
	struct quota_info *dqopt = sb_dqopt(sb);

	/* Just unsuspend quotas? */
	BUG_ON(flags & DQUOT_SUSPENDED);

	if (!flags)
		return 0;
	/* Just updating flags needed? */
	if (sb_has_quota_loaded(sb, type)) {
		mutex_lock(&dqopt->dqonoff_mutex);
		/* Now do a reliable test... */
		if (!sb_has_quota_loaded(sb, type)) {
			mutex_unlock(&dqopt->dqonoff_mutex);
			goto load_quota;
		}
		if (flags & DQUOT_USAGE_ENABLED &&
		    sb_has_quota_usage_enabled(sb, type)) {
			ret = -EBUSY;
			goto out_lock;
		}
		if (flags & DQUOT_LIMITS_ENABLED &&
		    sb_has_quota_limits_enabled(sb, type)) {
			ret = -EBUSY;
			goto out_lock;
		}
		spin_lock(&dq_state_lock);
		sb_dqopt(sb)->flags |= dquot_state_flag(flags, type);
		spin_unlock(&dq_state_lock);
out_lock:
		mutex_unlock(&dqopt->dqonoff_mutex);
		return ret;
	}

load_quota:
	return vfs_load_quota_inode(inode, type, format_id, flags);
}
EXPORT_SYMBOL(dquot_enable);

/*
 * This function is used when filesystem needs to initialize quotas
 * during mount time.
 */
int dquot_quota_on_mount(struct super_block *sb, char *qf_name,
		int format_id, int type)
{
	struct dentry *dentry;
	int error;

	mutex_lock(&sb->s_root->d_inode->i_mutex);
	dentry = lookup_one_len(qf_name, sb->s_root, strlen(qf_name));
	mutex_unlock(&sb->s_root->d_inode->i_mutex);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	if (!dentry->d_inode) {
		error = -ENOENT;
		goto out;
	}

	error = security_quota_on(dentry);
	if (!error)
		error = vfs_load_quota_inode(dentry->d_inode, type, format_id,
				DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);

out:
	dput(dentry);
	return error;
}
EXPORT_SYMBOL(dquot_quota_on_mount);

static inline qsize_t qbtos(qsize_t blocks)
{
	return blocks << QIF_DQBLKSIZE_BITS;
}

static inline qsize_t stoqb(qsize_t space)
{
	return (space + QIF_DQBLKSIZE - 1) >> QIF_DQBLKSIZE_BITS;
}

/* Generic routine for getting common part of quota structure */
static void do_get_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
{
	struct mem_dqblk *dm = &dquot->dq_dqb;

	memset(di, 0, sizeof(*di));
	di->d_version = FS_DQUOT_VERSION;
	di->d_flags = dquot->dq_id.type == USRQUOTA ?
			FS_USER_QUOTA : FS_GROUP_QUOTA;
	di->d_id = from_kqid_munged(current_user_ns(), dquot->dq_id);

	spin_lock(&dq_data_lock);
	di->d_blk_hardlimit = stoqb(dm->dqb_bhardlimit);
	di->d_blk_softlimit = stoqb(dm->dqb_bsoftlimit);
	di->d_ino_hardlimit = dm->dqb_ihardlimit;
	di->d_ino_softlimit = dm->dqb_isoftlimit;
	di->d_bcount = dm->dqb_curspace + dm->dqb_rsvspace;
	di->d_icount = dm->dqb_curinodes;
	di->d_btimer = dm->dqb_btime;
	di->d_itimer = dm->dqb_itime;
	spin_unlock(&dq_data_lock);
}

int dquot_get_dqblk(struct super_block *sb, struct kqid qid,
		    struct fs_disk_quota *di)
{
	struct dquot *dquot;

	dquot = dqget(sb, qid);
	if (!dquot)
		return -ESRCH;
	do_get_dqblk(dquot, di);
	dqput(dquot);

	return 0;
}
EXPORT_SYMBOL(dquot_get_dqblk);

#define VFS_FS_DQ_MASK \
	(FS_DQ_BCOUNT | FS_DQ_BSOFT | FS_DQ_BHARD | \
	 FS_DQ_ICOUNT | FS_DQ_ISOFT | FS_DQ_IHARD | \
	 FS_DQ_BTIMER | FS_DQ_ITIMER)

/* Generic routine for setting common part of quota structure */
static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
{
	struct mem_dqblk *dm = &dquot->dq_dqb;
	int check_blim = 0, check_ilim = 0;
	struct mem_dqinfo *dqi = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_id.type];

	if (di->d_fieldmask & ~VFS_FS_DQ_MASK)
		return -EINVAL;

	if (((di->d_fieldmask & FS_DQ_BSOFT) &&
	     (di->d_blk_softlimit > dqi->dqi_maxblimit)) ||
	    ((di->d_fieldmask & FS_DQ_BHARD) &&
	     (di->d_blk_hardlimit > dqi->dqi_maxblimit)) ||
	    ((di->d_fieldmask & FS_DQ_ISOFT) &&
	     (di->d_ino_softlimit > dqi->dqi_maxilimit)) ||
	    ((di->d_fieldmask & FS_DQ_IHARD) &&
	     (di->d_ino_hardlimit > dqi->dqi_maxilimit)))
		return -ERANGE;

	spin_lock(&dq_data_lock);
	if (di->d_fieldmask & FS_DQ_BCOUNT) {
		dm->dqb_curspace = di->d_bcount - dm->dqb_rsvspace;
		check_blim = 1;
		set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
	}

	if (di->d_fieldmask & FS_DQ_BSOFT)
		dm->dqb_bsoftlimit = qbtos(di->d_blk_softlimit);
	if (di->d_fieldmask & FS_DQ_BHARD)
		dm->dqb_bhardlimit = qbtos(di->d_blk_hardlimit);
	if (di->d_fieldmask & (FS_DQ_BSOFT | FS_DQ_BHARD)) {
		check_blim = 1;
		set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
	}

	if (di->d_fieldmask & FS_DQ_ICOUNT) {
		dm->dqb_curinodes = di->d_icount;
		check_ilim = 1;
		set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
	}

	if (di->d_fieldmask & FS_DQ_ISOFT)
		dm->dqb_isoftlimit = di->d_ino_softlimit;
	if (di->d_fieldmask & FS_DQ_IHARD)
		dm->dqb_ihardlimit = di->d_ino_hardlimit;
	if (di->d_fieldmask & (FS_DQ_ISOFT | FS_DQ_IHARD)) {
		check_ilim = 1;
		set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
	}

	if (di->d_fieldmask & FS_DQ_BTIMER) {
		dm->dqb_btime = di->d_btimer;
		check_blim = 1;
		set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
	}

	if (di->d_fieldmask & FS_DQ_ITIMER) {
		dm->dqb_itime = di->d_itimer;
		check_ilim = 1;
		set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
	}

	if (check_blim) {
		if (!dm->dqb_bsoftlimit ||
		    dm->dqb_curspace < dm->dqb_bsoftlimit) {
			dm->dqb_btime = 0;
			clear_bit(DQ_BLKS_B, &dquot->dq_flags);
		} else if (!(di->d_fieldmask & FS_DQ_BTIMER))
			/* Set grace only if user hasn't provided his own... */
			dm->dqb_btime = get_seconds() + dqi->dqi_bgrace;
	}
	if (check_ilim) {
		if (!dm->dqb_isoftlimit ||
		    dm->dqb_curinodes < dm->dqb_isoftlimit) {
			dm->dqb_itime = 0;
			clear_bit(DQ_INODES_B, &dquot->dq_flags);
		} else if (!(di->d_fieldmask & FS_DQ_ITIMER))
			/* Set grace only if user hasn't provided his own... */
			dm->dqb_itime = get_seconds() + dqi->dqi_igrace;
	}
	if (dm->dqb_bhardlimit || dm->dqb_bsoftlimit || dm->dqb_ihardlimit ||
	    dm->dqb_isoftlimit)
		clear_bit(DQ_FAKE_B, &dquot->dq_flags);
	else
		set_bit(DQ_FAKE_B, &dquot->dq_flags);
	spin_unlock(&dq_data_lock);
	mark_dquot_dirty(dquot);

	return 0;
}

int dquot_set_dqblk(struct super_block *sb, struct kqid qid,
		  struct fs_disk_quota *di)
{
	struct dquot *dquot;
	int rc;

	dquot = dqget(sb, qid);
	if (!dquot) {
		rc = -ESRCH;
		goto out;
	}
	rc = do_set_dqblk(dquot, di);
	dqput(dquot);
out:
	return rc;
}
EXPORT_SYMBOL(dquot_set_dqblk);

/* Generic routine for getting common part of quota file information */
int dquot_get_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii)
{
	struct mem_dqinfo *mi;
  
	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
	if (!sb_has_quota_active(sb, type)) {
		mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
		return -ESRCH;
	}
	mi = sb_dqopt(sb)->info + type;
	spin_lock(&dq_data_lock);
	ii->dqi_bgrace = mi->dqi_bgrace;
	ii->dqi_igrace = mi->dqi_igrace;
	ii->dqi_flags = mi->dqi_flags & DQF_GETINFO_MASK;
	ii->dqi_valid = IIF_ALL;
	spin_unlock(&dq_data_lock);
	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
	return 0;
}
EXPORT_SYMBOL(dquot_get_dqinfo);

/* Generic routine for setting common part of quota file information */
int dquot_set_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii)
{
	struct mem_dqinfo *mi;
	int err = 0;

	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
	if (!sb_has_quota_active(sb, type)) {
		err = -ESRCH;
		goto out;
	}
	mi = sb_dqopt(sb)->info + type;
	spin_lock(&dq_data_lock);
	if (ii->dqi_valid & IIF_BGRACE)
		mi->dqi_bgrace = ii->dqi_bgrace;
	if (ii->dqi_valid & IIF_IGRACE)
		mi->dqi_igrace = ii->dqi_igrace;
	if (ii->dqi_valid & IIF_FLAGS)
		mi->dqi_flags = (mi->dqi_flags & ~DQF_SETINFO_MASK) |
				(ii->dqi_flags & DQF_SETINFO_MASK);
	spin_unlock(&dq_data_lock);
	mark_info_dirty(sb, type);
	/* Force write to disk */
	sb->dq_op->write_info(sb, type);
out:
	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
	return err;
}
EXPORT_SYMBOL(dquot_set_dqinfo);

const struct quotactl_ops dquot_quotactl_ops = {
	.quota_on	= dquot_quota_on,
	.quota_off	= dquot_quota_off,
	.quota_sync	= dquot_quota_sync,
	.get_info	= dquot_get_dqinfo,
	.set_info	= dquot_set_dqinfo,
	.get_dqblk	= dquot_get_dqblk,
	.set_dqblk	= dquot_set_dqblk
};
EXPORT_SYMBOL(dquot_quotactl_ops);

static int do_proc_dqstats(struct ctl_table *table, int write,
		     void __user *buffer, size_t *lenp, loff_t *ppos)
{
	unsigned int type = (int *)table->data - dqstats.stat;

	/* Update global table */
	dqstats.stat[type] =
			percpu_counter_sum_positive(&dqstats.counter[type]);
	return proc_dointvec(table, write, buffer, lenp, ppos);
}

static struct ctl_table fs_dqstats_table[] = {
	{
		.procname	= "lookups",
		.data		= &dqstats.stat[DQST_LOOKUPS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "drops",
		.data		= &dqstats.stat[DQST_DROPS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "reads",
		.data		= &dqstats.stat[DQST_READS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "writes",
		.data		= &dqstats.stat[DQST_WRITES],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "cache_hits",
		.data		= &dqstats.stat[DQST_CACHE_HITS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "allocated_dquots",
		.data		= &dqstats.stat[DQST_ALLOC_DQUOTS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "free_dquots",
		.data		= &dqstats.stat[DQST_FREE_DQUOTS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
	{
		.procname	= "syncs",
		.data		= &dqstats.stat[DQST_SYNCS],
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= do_proc_dqstats,
	},
#ifdef CONFIG_PRINT_QUOTA_WARNING
	{
		.procname	= "warnings",
		.data		= &flag_print_warnings,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
#endif
	{ },
};

static struct ctl_table fs_table[] = {
	{
		.procname	= "quota",
		.mode		= 0555,
		.child		= fs_dqstats_table,
	},
	{ },
};

static struct ctl_table sys_table[] = {
	{
		.procname	= "fs",
		.mode		= 0555,
		.child		= fs_table,
	},
	{ },
};

static int __init dquot_init(void)
{
	int i, ret;
	unsigned long nr_hash, order;

	printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);

	register_sysctl_table(sys_table);

	dquot_cachep = kmem_cache_create("dquot",
			sizeof(struct dquot), sizeof(unsigned long) * 4,
			(SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
				SLAB_MEM_SPREAD|SLAB_PANIC),
			NULL);

	order = 0;
	dquot_hash = (struct hlist_head *)__get_free_pages(GFP_ATOMIC, order);
	if (!dquot_hash)
		panic("Cannot create dquot hash table");

	for (i = 0; i < _DQST_DQSTAT_LAST; i++) {
		ret = percpu_counter_init(&dqstats.counter[i], 0);
		if (ret)
			panic("Cannot create dquot stat counters");
	}

	/* Find power-of-two hlist_heads which can fit into allocation */
	nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
	dq_hash_bits = 0;
	do {
		dq_hash_bits++;
	} while (nr_hash >> dq_hash_bits);
	dq_hash_bits--;

	nr_hash = 1UL << dq_hash_bits;
	dq_hash_mask = nr_hash - 1;
	for (i = 0; i < nr_hash; i++)
		INIT_HLIST_HEAD(dquot_hash + i);

	printk("Dquot-cache hash table entries: %ld (order %ld, %ld bytes)\n",
			nr_hash, order, (PAGE_SIZE << order));

	register_shrinker(&dqcache_shrinker);

	return 0;
}
module_init(dquot_init);