Free Electrons

Embedded Linux Experts

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
/*
   SCSI Tape Driver for Linux version 1.1 and newer. See the accompanying
   file Documentation/scsi/st.txt for more information.

   History:
   Rewritten from Dwayne Forsyth's SCSI tape driver by Kai Makisara.
   Contribution and ideas from several people including (in alphabetical
   order) Klaus Ehrenfried, Eugene Exarevsky, Eric Lee Green, Wolfgang Denk,
   Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
   Michael Schaefer, J"org Weule, and Eric Youngdale.

   Copyright 1992 - 2010 Kai Makisara
   email Kai.Makisara@kolumbus.fi

   Some small formal changes - aeb, 950809

   Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
 */

static const char *verstr = "20101219";

#include <linux/module.h>

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/mtio.h>
#include <linux/cdrom.h>
#include <linux/ioctl.h>
#include <linux/fcntl.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/moduleparam.h>
#include <linux/cdev.h>
#include <linux/delay.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>
#include <asm/dma.h>

#include <scsi/scsi.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/sg.h>


/* The driver prints some debugging information on the console if DEBUG
   is defined and non-zero. */
#define DEBUG 0

#if DEBUG
/* The message level for the debug messages is currently set to KERN_NOTICE
   so that people can easily see the messages. Later when the debugging messages
   in the drivers are more widely classified, this may be changed to KERN_DEBUG. */
#define ST_DEB_MSG  KERN_NOTICE
#define DEB(a) a
#define DEBC(a) if (debugging) { a ; }
#else
#define DEB(a)
#define DEBC(a)
#endif

#define ST_KILOBYTE 1024

#include "st_options.h"
#include "st.h"

static DEFINE_MUTEX(st_mutex);
static int buffer_kbs;
static int max_sg_segs;
static int try_direct_io = TRY_DIRECT_IO;
static int try_rdio = 1;
static int try_wdio = 1;

static int st_dev_max;
static int st_nr_dev;

static struct class *st_sysfs_class;

MODULE_AUTHOR("Kai Makisara");
MODULE_DESCRIPTION("SCSI tape (st) driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(SCSI_TAPE_MAJOR);
MODULE_ALIAS_SCSI_DEVICE(TYPE_TAPE);

/* Set 'perm' (4th argument) to 0 to disable module_param's definition
 * of sysfs parameters (which module_param doesn't yet support).
 * Sysfs parameters defined explicitly later.
 */
module_param_named(buffer_kbs, buffer_kbs, int, 0);
MODULE_PARM_DESC(buffer_kbs, "Default driver buffer size for fixed block mode (KB; 32)");
module_param_named(max_sg_segs, max_sg_segs, int, 0);
MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
module_param_named(try_direct_io, try_direct_io, int, 0);
MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");

/* Extra parameters for testing */
module_param_named(try_rdio, try_rdio, int, 0);
MODULE_PARM_DESC(try_rdio, "Try direct read i/o when possible");
module_param_named(try_wdio, try_wdio, int, 0);
MODULE_PARM_DESC(try_wdio, "Try direct write i/o when possible");

#ifndef MODULE
static int write_threshold_kbs;  /* retained for compatibility */
static struct st_dev_parm {
	char *name;
	int *val;
} parms[] __initdata = {
	{
		"buffer_kbs", &buffer_kbs
	},
	{       /* Retained for compatibility with 2.4 */
		"write_threshold_kbs", &write_threshold_kbs
	},
	{
		"max_sg_segs", NULL
	},
	{
		"try_direct_io", &try_direct_io
	}
};
#endif

/* Restrict the number of modes so that names for all are assigned */
#if ST_NBR_MODES > 16
#error "Maximum number of modes is 16"
#endif
/* Bit reversed order to get same names for same minors with all
   mode counts */
static const char *st_formats[] = {
	"",  "r", "k", "s", "l", "t", "o", "u",
	"m", "v", "p", "x", "a", "y", "q", "z"}; 

/* The default definitions have been moved to st_options.h */

#define ST_FIXED_BUFFER_SIZE (ST_FIXED_BUFFER_BLOCKS * ST_KILOBYTE)

/* The buffer size should fit into the 24 bits for length in the
   6-byte SCSI read and write commands. */
#if ST_FIXED_BUFFER_SIZE >= (2 << 24 - 1)
#error "Buffer size should not exceed (2 << 24 - 1) bytes!"
#endif

static int debugging = DEBUG;

#define MAX_RETRIES 0
#define MAX_WRITE_RETRIES 0
#define MAX_READY_RETRIES 0
#define NO_TAPE  NOT_READY

#define ST_TIMEOUT (900 * HZ)
#define ST_LONG_TIMEOUT (14000 * HZ)

/* Remove mode bits and auto-rewind bit (7) */
#define TAPE_NR(x) ( ((iminor(x) & ~255) >> (ST_NBR_MODE_BITS + 1)) | \
    (iminor(x) & ~(-1 << ST_MODE_SHIFT)) )
#define TAPE_MODE(x) ((iminor(x) & ST_MODE_MASK) >> ST_MODE_SHIFT)

/* Construct the minor number from the device (d), mode (m), and non-rewind (n) data */
#define TAPE_MINOR(d, m, n) (((d & ~(255 >> (ST_NBR_MODE_BITS + 1))) << (ST_NBR_MODE_BITS + 1)) | \
  (d & (255 >> (ST_NBR_MODE_BITS + 1))) | (m << ST_MODE_SHIFT) | ((n != 0) << 7) )

/* Internal ioctl to set both density (uppermost 8 bits) and blocksize (lower
   24 bits) */
#define SET_DENS_AND_BLK 0x10001

static DEFINE_RWLOCK(st_dev_arr_lock);

static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
static int st_max_sg_segs = ST_MAX_SG;

static struct scsi_tape **scsi_tapes = NULL;

static int modes_defined;

static int enlarge_buffer(struct st_buffer *, int, int);
static void clear_buffer(struct st_buffer *);
static void normalize_buffer(struct st_buffer *);
static int append_to_buffer(const char __user *, struct st_buffer *, int);
static int from_buffer(struct st_buffer *, char __user *, int);
static void move_buffer_data(struct st_buffer *, int);

static int sgl_map_user_pages(struct st_buffer *, const unsigned int,
			      unsigned long, size_t, int);
static int sgl_unmap_user_pages(struct st_buffer *, const unsigned int, int);

static int st_probe(struct device *);
static int st_remove(struct device *);

static int do_create_sysfs_files(void);
static void do_remove_sysfs_files(void);
static int do_create_class_files(struct scsi_tape *, int, int);

static struct scsi_driver st_template = {
	.owner			= THIS_MODULE,
	.gendrv = {
		.name		= "st",
		.probe		= st_probe,
		.remove		= st_remove,
	},
};

static int st_compression(struct scsi_tape *, int);

static int find_partition(struct scsi_tape *);
static int switch_partition(struct scsi_tape *);

static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);

static void scsi_tape_release(struct kref *);

#define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)

static DEFINE_MUTEX(st_ref_mutex);


#include "osst_detect.h"
#ifndef SIGS_FROM_OSST
#define SIGS_FROM_OSST \
	{"OnStream", "SC-", "", "osst"}, \
	{"OnStream", "DI-", "", "osst"}, \
	{"OnStream", "DP-", "", "osst"}, \
	{"OnStream", "USB", "", "osst"}, \
	{"OnStream", "FW-", "", "osst"}
#endif

static struct scsi_tape *scsi_tape_get(int dev)
{
	struct scsi_tape *STp = NULL;

	mutex_lock(&st_ref_mutex);
	write_lock(&st_dev_arr_lock);

	if (dev < st_dev_max && scsi_tapes != NULL)
		STp = scsi_tapes[dev];
	if (!STp) goto out;

	kref_get(&STp->kref);

	if (!STp->device)
		goto out_put;

	if (scsi_device_get(STp->device))
		goto out_put;

	goto out;

out_put:
	kref_put(&STp->kref, scsi_tape_release);
	STp = NULL;
out:
	write_unlock(&st_dev_arr_lock);
	mutex_unlock(&st_ref_mutex);
	return STp;
}

static void scsi_tape_put(struct scsi_tape *STp)
{
	struct scsi_device *sdev = STp->device;

	mutex_lock(&st_ref_mutex);
	kref_put(&STp->kref, scsi_tape_release);
	scsi_device_put(sdev);
	mutex_unlock(&st_ref_mutex);
}

struct st_reject_data {
	char *vendor;
	char *model;
	char *rev;
	char *driver_hint; /* Name of the correct driver, NULL if unknown */
};

static struct st_reject_data reject_list[] = {
	/* {"XXX", "Yy-", "", NULL},  example */
	SIGS_FROM_OSST,
	{NULL, }};

/* If the device signature is on the list of incompatible drives, the
   function returns a pointer to the name of the correct driver (if known) */
static char * st_incompatible(struct scsi_device* SDp)
{
	struct st_reject_data *rp;

	for (rp=&(reject_list[0]); rp->vendor != NULL; rp++)
		if (!strncmp(rp->vendor, SDp->vendor, strlen(rp->vendor)) &&
		    !strncmp(rp->model, SDp->model, strlen(rp->model)) &&
		    !strncmp(rp->rev, SDp->rev, strlen(rp->rev))) {
			if (rp->driver_hint)
				return rp->driver_hint;
			else
				return "unknown";
		}
	return NULL;
}


static inline char *tape_name(struct scsi_tape *tape)
{
	return tape->disk->disk_name;
}


static void st_analyze_sense(struct st_request *SRpnt, struct st_cmdstatus *s)
{
	const u8 *ucp;
	const u8 *sense = SRpnt->sense;

	s->have_sense = scsi_normalize_sense(SRpnt->sense,
				SCSI_SENSE_BUFFERSIZE, &s->sense_hdr);
	s->flags = 0;

	if (s->have_sense) {
		s->deferred = 0;
		s->remainder_valid =
			scsi_get_sense_info_fld(sense, SCSI_SENSE_BUFFERSIZE, &s->uremainder64);
		switch (sense[0] & 0x7f) {
		case 0x71:
			s->deferred = 1;
		case 0x70:
			s->fixed_format = 1;
			s->flags = sense[2] & 0xe0;
			break;
		case 0x73:
			s->deferred = 1;
		case 0x72:
			s->fixed_format = 0;
			ucp = scsi_sense_desc_find(sense, SCSI_SENSE_BUFFERSIZE, 4);
			s->flags = ucp ? (ucp[3] & 0xe0) : 0;
			break;
		}
	}
}


/* Convert the result to success code */
static int st_chk_result(struct scsi_tape *STp, struct st_request * SRpnt)
{
	int result = SRpnt->result;
	u8 scode;
	DEB(const char *stp;)
	char *name = tape_name(STp);
	struct st_cmdstatus *cmdstatp;

	if (!result)
		return 0;

	cmdstatp = &STp->buffer->cmdstat;
	st_analyze_sense(SRpnt, cmdstatp);

	if (cmdstatp->have_sense)
		scode = STp->buffer->cmdstat.sense_hdr.sense_key;
	else
		scode = 0;

        DEB(
        if (debugging) {
                printk(ST_DEB_MSG "%s: Error: %x, cmd: %x %x %x %x %x %x\n",
		       name, result,
		       SRpnt->cmd[0], SRpnt->cmd[1], SRpnt->cmd[2],
		       SRpnt->cmd[3], SRpnt->cmd[4], SRpnt->cmd[5]);
		if (cmdstatp->have_sense)
			 __scsi_print_sense(name, SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
	} ) /* end DEB */
	if (!debugging) { /* Abnormal conditions for tape */
		if (!cmdstatp->have_sense)
			printk(KERN_WARNING
			       "%s: Error %x (driver bt 0x%x, host bt 0x%x).\n",
			       name, result, driver_byte(result),
			       host_byte(result));
		else if (cmdstatp->have_sense &&
			 scode != NO_SENSE &&
			 scode != RECOVERED_ERROR &&
			 /* scode != UNIT_ATTENTION && */
			 scode != BLANK_CHECK &&
			 scode != VOLUME_OVERFLOW &&
			 SRpnt->cmd[0] != MODE_SENSE &&
			 SRpnt->cmd[0] != TEST_UNIT_READY) {

			__scsi_print_sense(name, SRpnt->sense, SCSI_SENSE_BUFFERSIZE);
		}
	}

	if (cmdstatp->fixed_format &&
	    STp->cln_mode >= EXTENDED_SENSE_START) {  /* Only fixed format sense */
		if (STp->cln_sense_value)
			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
					       STp->cln_sense_mask) == STp->cln_sense_value);
		else
			STp->cleaning_req |= ((SRpnt->sense[STp->cln_mode] &
					       STp->cln_sense_mask) != 0);
	}
	if (cmdstatp->have_sense &&
	    cmdstatp->sense_hdr.asc == 0 && cmdstatp->sense_hdr.ascq == 0x17)
		STp->cleaning_req = 1; /* ASC and ASCQ => cleaning requested */

	STp->pos_unknown |= STp->device->was_reset;

	if (cmdstatp->have_sense &&
	    scode == RECOVERED_ERROR
#if ST_RECOVERED_WRITE_FATAL
	    && SRpnt->cmd[0] != WRITE_6
	    && SRpnt->cmd[0] != WRITE_FILEMARKS
#endif
	    ) {
		STp->recover_count++;
		STp->recover_reg++;

                DEB(
		if (debugging) {
			if (SRpnt->cmd[0] == READ_6)
				stp = "read";
			else if (SRpnt->cmd[0] == WRITE_6)
				stp = "write";
			else
				stp = "ioctl";
			printk(ST_DEB_MSG "%s: Recovered %s error (%d).\n", name, stp,
			       STp->recover_count);
		} ) /* end DEB */

		if (cmdstatp->flags == 0)
			return 0;
	}
	return (-EIO);
}

static struct st_request *st_allocate_request(struct scsi_tape *stp)
{
	struct st_request *streq;

	streq = kzalloc(sizeof(*streq), GFP_KERNEL);
	if (streq)
		streq->stp = stp;
	else {
		DEBC(printk(KERN_ERR "%s: Can't get SCSI request.\n",
			    tape_name(stp)););
		if (signal_pending(current))
			stp->buffer->syscall_result = -EINTR;
		else
			stp->buffer->syscall_result = -EBUSY;
	}

	return streq;
}

static void st_release_request(struct st_request *streq)
{
	kfree(streq);
}

static void st_scsi_execute_end(struct request *req, int uptodate)
{
	struct st_request *SRpnt = req->end_io_data;
	struct scsi_tape *STp = SRpnt->stp;
	struct bio *tmp;

	STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors;
	STp->buffer->cmdstat.residual = req->resid_len;

	tmp = SRpnt->bio;
	if (SRpnt->waiting)
		complete(SRpnt->waiting);

	blk_rq_unmap_user(tmp);
	__blk_put_request(req->q, req);
}

static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
			   int data_direction, void *buffer, unsigned bufflen,
			   int timeout, int retries)
{
	struct request *req;
	struct rq_map_data *mdata = &SRpnt->stp->buffer->map_data;
	int err = 0;
	int write = (data_direction == DMA_TO_DEVICE);

	req = blk_get_request(SRpnt->stp->device->request_queue, write,
			      GFP_KERNEL);
	if (!req)
		return DRIVER_ERROR << 24;

	req->cmd_type = REQ_TYPE_BLOCK_PC;
	req->cmd_flags |= REQ_QUIET;

	mdata->null_mapped = 1;

	if (bufflen) {
		err = blk_rq_map_user(req->q, req, mdata, NULL, bufflen,
				      GFP_KERNEL);
		if (err) {
			blk_put_request(req);
			return DRIVER_ERROR << 24;
		}
	}

	SRpnt->bio = req->bio;
	req->cmd_len = COMMAND_SIZE(cmd[0]);
	memset(req->cmd, 0, BLK_MAX_CDB);
	memcpy(req->cmd, cmd, req->cmd_len);
	req->sense = SRpnt->sense;
	req->sense_len = 0;
	req->timeout = timeout;
	req->retries = retries;
	req->end_io_data = SRpnt;

	blk_execute_rq_nowait(req->q, NULL, req, 1, st_scsi_execute_end);
	return 0;
}

/* Do the scsi command. Waits until command performed if do_wait is true.
   Otherwise write_behind_check() is used to check that the command
   has finished. */
static struct st_request *
st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
	   int bytes, int direction, int timeout, int retries, int do_wait)
{
	struct completion *waiting;
	struct rq_map_data *mdata = &STp->buffer->map_data;
	int ret;

	/* if async, make sure there's no command outstanding */
	if (!do_wait && ((STp->buffer)->last_SRpnt)) {
		printk(KERN_ERR "%s: Async command already active.\n",
		       tape_name(STp));
		if (signal_pending(current))
			(STp->buffer)->syscall_result = (-EINTR);
		else
			(STp->buffer)->syscall_result = (-EBUSY);
		return NULL;
	}

	if (!SRpnt) {
		SRpnt = st_allocate_request(STp);
		if (!SRpnt)
			return NULL;
	}

	/* If async IO, set last_SRpnt. This ptr tells write_behind_check
	   which IO is outstanding. It's nulled out when the IO completes. */
	if (!do_wait)
		(STp->buffer)->last_SRpnt = SRpnt;

	waiting = &STp->wait;
	init_completion(waiting);
	SRpnt->waiting = waiting;

	if (STp->buffer->do_dio) {
		mdata->page_order = 0;
		mdata->nr_entries = STp->buffer->sg_segs;
		mdata->pages = STp->buffer->mapped_pages;
	} else {
		mdata->page_order = STp->buffer->reserved_page_order;
		mdata->nr_entries =
			DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
		mdata->pages = STp->buffer->reserved_pages;
		mdata->offset = 0;
	}

	memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
	STp->buffer->cmdstat.have_sense = 0;
	STp->buffer->syscall_result = 0;

	ret = st_scsi_execute(SRpnt, cmd, direction, NULL, bytes, timeout,
			      retries);
	if (ret) {
		/* could not allocate the buffer or request was too large */
		(STp->buffer)->syscall_result = (-EBUSY);
		(STp->buffer)->last_SRpnt = NULL;
	} else if (do_wait) {
		wait_for_completion(waiting);
		SRpnt->waiting = NULL;
		(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
	}

	return SRpnt;
}


/* Handle the write-behind checking (waits for completion). Returns -ENOSPC if
   write has been correct but EOM early warning reached, -EIO if write ended in
   error or zero if write successful. Asynchronous writes are used only in
   variable block mode. */
static int write_behind_check(struct scsi_tape * STp)
{
	int retval = 0;
	struct st_buffer *STbuffer;
	struct st_partstat *STps;
	struct st_cmdstatus *cmdstatp;
	struct st_request *SRpnt;

	STbuffer = STp->buffer;
	if (!STbuffer->writing)
		return 0;

        DEB(
	if (STp->write_pending)
		STp->nbr_waits++;
	else
		STp->nbr_finished++;
        ) /* end DEB */

	wait_for_completion(&(STp->wait));
	SRpnt = STbuffer->last_SRpnt;
	STbuffer->last_SRpnt = NULL;
	SRpnt->waiting = NULL;

	(STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
	st_release_request(SRpnt);

	STbuffer->buffer_bytes -= STbuffer->writing;
	STps = &(STp->ps[STp->partition]);
	if (STps->drv_block >= 0) {
		if (STp->block_size == 0)
			STps->drv_block++;
		else
			STps->drv_block += STbuffer->writing / STp->block_size;
	}

	cmdstatp = &STbuffer->cmdstat;
	if (STbuffer->syscall_result) {
		retval = -EIO;
		if (cmdstatp->have_sense && !cmdstatp->deferred &&
		    (cmdstatp->flags & SENSE_EOM) &&
		    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
		     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR)) {
			/* EOM at write-behind, has all data been written? */
			if (!cmdstatp->remainder_valid ||
			    cmdstatp->uremainder64 == 0)
				retval = -ENOSPC;
		}
		if (retval == -EIO)
			STps->drv_block = -1;
	}
	STbuffer->writing = 0;

	DEB(if (debugging && retval)
	    printk(ST_DEB_MSG "%s: Async write error %x, return value %d.\n",
		   tape_name(STp), STbuffer->cmdstat.midlevel_result, retval);) /* end DEB */

	return retval;
}


/* Step over EOF if it has been inadvertently crossed (ioctl not used because
   it messes up the block number). */
static int cross_eof(struct scsi_tape * STp, int forward)
{
	struct st_request *SRpnt;
	unsigned char cmd[MAX_COMMAND_SIZE];

	cmd[0] = SPACE;
	cmd[1] = 0x01;		/* Space FileMarks */
	if (forward) {
		cmd[2] = cmd[3] = 0;
		cmd[4] = 1;
	} else
		cmd[2] = cmd[3] = cmd[4] = 0xff;	/* -1 filemarks */
	cmd[5] = 0;

        DEBC(printk(ST_DEB_MSG "%s: Stepping over filemark %s.\n",
		   tape_name(STp), forward ? "forward" : "backward"));

	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
			   STp->device->request_queue->rq_timeout,
			   MAX_RETRIES, 1);
	if (!SRpnt)
		return (STp->buffer)->syscall_result;

	st_release_request(SRpnt);
	SRpnt = NULL;

	if ((STp->buffer)->cmdstat.midlevel_result != 0)
		printk(KERN_ERR "%s: Stepping over filemark %s failed.\n",
		   tape_name(STp), forward ? "forward" : "backward");

	return (STp->buffer)->syscall_result;
}


/* Flush the write buffer (never need to write if variable blocksize). */
static int st_flush_write_buffer(struct scsi_tape * STp)
{
	int transfer, blks;
	int result;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	struct st_partstat *STps;

	result = write_behind_check(STp);
	if (result)
		return result;

	result = 0;
	if (STp->dirty == 1) {

		transfer = STp->buffer->buffer_bytes;
                DEBC(printk(ST_DEB_MSG "%s: Flushing %d bytes.\n",
                               tape_name(STp), transfer));

		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = WRITE_6;
		cmd[1] = 1;
		blks = transfer / STp->block_size;
		cmd[2] = blks >> 16;
		cmd[3] = blks >> 8;
		cmd[4] = blks;

		SRpnt = st_do_scsi(NULL, STp, cmd, transfer, DMA_TO_DEVICE,
				   STp->device->request_queue->rq_timeout,
				   MAX_WRITE_RETRIES, 1);
		if (!SRpnt)
			return (STp->buffer)->syscall_result;

		STps = &(STp->ps[STp->partition]);
		if ((STp->buffer)->syscall_result != 0) {
			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

			if (cmdstatp->have_sense && !cmdstatp->deferred &&
			    (cmdstatp->flags & SENSE_EOM) &&
			    (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
			     cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
			    (!cmdstatp->remainder_valid ||
			     cmdstatp->uremainder64 == 0)) { /* All written at EOM early warning */
				STp->dirty = 0;
				(STp->buffer)->buffer_bytes = 0;
				if (STps->drv_block >= 0)
					STps->drv_block += blks;
				result = (-ENOSPC);
			} else {
				printk(KERN_ERR "%s: Error on flush.\n",
                                       tape_name(STp));
				STps->drv_block = (-1);
				result = (-EIO);
			}
		} else {
			if (STps->drv_block >= 0)
				STps->drv_block += blks;
			STp->dirty = 0;
			(STp->buffer)->buffer_bytes = 0;
		}
		st_release_request(SRpnt);
		SRpnt = NULL;
	}
	return result;
}


/* Flush the tape buffer. The tape will be positioned correctly unless
   seek_next is true. */
static int flush_buffer(struct scsi_tape *STp, int seek_next)
{
	int backspace, result;
	struct st_buffer *STbuffer;
	struct st_partstat *STps;

	STbuffer = STp->buffer;

	/*
	 * If there was a bus reset, block further access
	 * to this device.
	 */
	if (STp->pos_unknown)
		return (-EIO);

	if (STp->ready != ST_READY)
		return 0;
	STps = &(STp->ps[STp->partition]);
	if (STps->rw == ST_WRITING)	/* Writing */
		return st_flush_write_buffer(STp);

	if (STp->block_size == 0)
		return 0;

	backspace = ((STp->buffer)->buffer_bytes +
		     (STp->buffer)->read_pointer) / STp->block_size -
	    ((STp->buffer)->read_pointer + STp->block_size - 1) /
	    STp->block_size;
	(STp->buffer)->buffer_bytes = 0;
	(STp->buffer)->read_pointer = 0;
	result = 0;
	if (!seek_next) {
		if (STps->eof == ST_FM_HIT) {
			result = cross_eof(STp, 0);	/* Back over the EOF hit */
			if (!result)
				STps->eof = ST_NOEOF;
			else {
				if (STps->drv_file >= 0)
					STps->drv_file++;
				STps->drv_block = 0;
			}
		}
		if (!result && backspace > 0)
			result = st_int_ioctl(STp, MTBSR, backspace);
	} else if (STps->eof == ST_FM_HIT) {
		if (STps->drv_file >= 0)
			STps->drv_file++;
		STps->drv_block = 0;
		STps->eof = ST_NOEOF;
	}
	return result;

}

/* Set the mode parameters */
static int set_mode_densblk(struct scsi_tape * STp, struct st_modedef * STm)
{
	int set_it = 0;
	unsigned long arg;
	char *name = tape_name(STp);

	if (!STp->density_changed &&
	    STm->default_density >= 0 &&
	    STm->default_density != STp->density) {
		arg = STm->default_density;
		set_it = 1;
	} else
		arg = STp->density;
	arg <<= MT_ST_DENSITY_SHIFT;
	if (!STp->blksize_changed &&
	    STm->default_blksize >= 0 &&
	    STm->default_blksize != STp->block_size) {
		arg |= STm->default_blksize;
		set_it = 1;
	} else
		arg |= STp->block_size;
	if (set_it &&
	    st_int_ioctl(STp, SET_DENS_AND_BLK, arg)) {
		printk(KERN_WARNING
		       "%s: Can't set default block size to %d bytes and density %x.\n",
		       name, STm->default_blksize, STm->default_density);
		if (modes_defined)
			return (-EINVAL);
	}
	return 0;
}


/* Lock or unlock the drive door. Don't use when st_request allocated. */
static int do_door_lock(struct scsi_tape * STp, int do_lock)
{
	int retval, cmd;
	DEB(char *name = tape_name(STp);)


	cmd = do_lock ? SCSI_IOCTL_DOORLOCK : SCSI_IOCTL_DOORUNLOCK;
	DEBC(printk(ST_DEB_MSG "%s: %socking drive door.\n", name,
		    do_lock ? "L" : "Unl"));
	retval = scsi_ioctl(STp->device, cmd, NULL);
	if (!retval) {
		STp->door_locked = do_lock ? ST_LOCKED_EXPLICIT : ST_UNLOCKED;
	}
	else {
		STp->door_locked = ST_LOCK_FAILS;
	}
	return retval;
}


/* Set the internal state after reset */
static void reset_state(struct scsi_tape *STp)
{
	int i;
	struct st_partstat *STps;

	STp->pos_unknown = 0;
	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
		STps = &(STp->ps[i]);
		STps->rw = ST_IDLE;
		STps->eof = ST_NOEOF;
		STps->at_sm = 0;
		STps->last_block_valid = 0;
		STps->drv_block = -1;
		STps->drv_file = -1;
	}
	if (STp->can_partitions) {
		STp->partition = find_partition(STp);
		if (STp->partition < 0)
			STp->partition = 0;
		STp->new_partition = STp->partition;
	}
}

/* Test if the drive is ready. Returns either one of the codes below or a negative system
   error code. */
#define CHKRES_READY       0
#define CHKRES_NEW_SESSION 1
#define CHKRES_NOT_READY   2
#define CHKRES_NO_TAPE     3

#define MAX_ATTENTIONS    10

static int test_ready(struct scsi_tape *STp, int do_wait)
{
	int attentions, waits, max_wait, scode;
	int retval = CHKRES_READY, new_session = 0;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt = NULL;
	struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

	max_wait = do_wait ? ST_BLOCK_SECONDS : 0;

	for (attentions=waits=0; ; ) {
		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
		cmd[0] = TEST_UNIT_READY;
		SRpnt = st_do_scsi(SRpnt, STp, cmd, 0, DMA_NONE,
				   STp->long_timeout, MAX_READY_RETRIES, 1);

		if (!SRpnt) {
			retval = (STp->buffer)->syscall_result;
			break;
		}

		if (cmdstatp->have_sense) {

			scode = cmdstatp->sense_hdr.sense_key;

			if (scode == UNIT_ATTENTION) { /* New media? */
				new_session = 1;
				if (attentions < MAX_ATTENTIONS) {
					attentions++;
					continue;
				}
				else {
					retval = (-EIO);
					break;
				}
			}

			if (scode == NOT_READY) {
				if (waits < max_wait) {
					if (msleep_interruptible(1000)) {
						retval = (-EINTR);
						break;
					}
					waits++;
					continue;
				}
				else {
					if ((STp->device)->scsi_level >= SCSI_2 &&
					    cmdstatp->sense_hdr.asc == 0x3a)	/* Check ASC */
						retval = CHKRES_NO_TAPE;
					else
						retval = CHKRES_NOT_READY;
					break;
				}
			}
		}

		retval = (STp->buffer)->syscall_result;
		if (!retval)
			retval = new_session ? CHKRES_NEW_SESSION : CHKRES_READY;
		break;
	}

	if (SRpnt != NULL)
		st_release_request(SRpnt);
	return retval;
}


/* See if the drive is ready and gather information about the tape. Return values:
   < 0   negative error code from errno.h
   0     drive ready
   1     drive not ready (possibly no tape)
*/
static int check_tape(struct scsi_tape *STp, struct file *filp)
{
	int i, retval, new_session = 0, do_wait;
	unsigned char cmd[MAX_COMMAND_SIZE], saved_cleaning;
	unsigned short st_flags = filp->f_flags;
	struct st_request *SRpnt = NULL;
	struct st_modedef *STm;
	struct st_partstat *STps;
	char *name = tape_name(STp);
	struct inode *inode = filp->f_path.dentry->d_inode;
	int mode = TAPE_MODE(inode);

	STp->ready = ST_READY;

	if (mode != STp->current_mode) {
                DEBC(printk(ST_DEB_MSG "%s: Mode change from %d to %d.\n",
			       name, STp->current_mode, mode));
		new_session = 1;
		STp->current_mode = mode;
	}
	STm = &(STp->modes[STp->current_mode]);

	saved_cleaning = STp->cleaning_req;
	STp->cleaning_req = 0;

	do_wait = ((filp->f_flags & O_NONBLOCK) == 0);
	retval = test_ready(STp, do_wait);

	if (retval < 0)
	    goto err_out;

	if (retval == CHKRES_NEW_SESSION) {
		STp->pos_unknown = 0;
		STp->partition = STp->new_partition = 0;
		if (STp->can_partitions)
			STp->nbr_partitions = 1; /* This guess will be updated later
                                                    if necessary */
		for (i = 0; i < ST_NBR_PARTITIONS; i++) {
			STps = &(STp->ps[i]);
			STps->rw = ST_IDLE;
			STps->eof = ST_NOEOF;
			STps->at_sm = 0;
			STps->last_block_valid = 0;
			STps->drv_block = 0;
			STps->drv_file = 0;
		}
		new_session = 1;
	}
	else {
		STp->cleaning_req |= saved_cleaning;

		if (retval == CHKRES_NOT_READY || retval == CHKRES_NO_TAPE) {
			if (retval == CHKRES_NO_TAPE)
				STp->ready = ST_NO_TAPE;
			else
				STp->ready = ST_NOT_READY;

			STp->density = 0;	/* Clear the erroneous "residue" */
			STp->write_prot = 0;
			STp->block_size = 0;
			STp->ps[0].drv_file = STp->ps[0].drv_block = (-1);
			STp->partition = STp->new_partition = 0;
			STp->door_locked = ST_UNLOCKED;
			return CHKRES_NOT_READY;
		}
	}

	if (STp->omit_blklims)
		STp->min_block = STp->max_block = (-1);
	else {
		memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
		cmd[0] = READ_BLOCK_LIMITS;

		SRpnt = st_do_scsi(SRpnt, STp, cmd, 6, DMA_FROM_DEVICE,
				   STp->device->request_queue->rq_timeout,
				   MAX_READY_RETRIES, 1);
		if (!SRpnt) {
			retval = (STp->buffer)->syscall_result;
			goto err_out;
		}

		if (!SRpnt->result && !STp->buffer->cmdstat.have_sense) {
			STp->max_block = ((STp->buffer)->b_data[1] << 16) |
			    ((STp->buffer)->b_data[2] << 8) | (STp->buffer)->b_data[3];
			STp->min_block = ((STp->buffer)->b_data[4] << 8) |
			    (STp->buffer)->b_data[5];
			if ( DEB( debugging || ) !STp->inited)
				printk(KERN_INFO
                                       "%s: Block limits %d - %d bytes.\n", name,
                                       STp->min_block, STp->max_block);
		} else {
			STp->min_block = STp->max_block = (-1);
                        DEBC(printk(ST_DEB_MSG "%s: Can't read block limits.\n",
                                       name));
		}
	}

	memset((void *) &cmd[0], 0, MAX_COMMAND_SIZE);
	cmd[0] = MODE_SENSE;
	cmd[4] = 12;

	SRpnt = st_do_scsi(SRpnt, STp, cmd, 12, DMA_FROM_DEVICE,
			   STp->device->request_queue->rq_timeout,
			   MAX_READY_RETRIES, 1);
	if (!SRpnt) {
		retval = (STp->buffer)->syscall_result;
		goto err_out;
	}

	if ((STp->buffer)->syscall_result != 0) {
                DEBC(printk(ST_DEB_MSG "%s: No Mode Sense.\n", name));
		STp->block_size = ST_DEFAULT_BLOCK;	/* Educated guess (?) */
		(STp->buffer)->syscall_result = 0;	/* Prevent error propagation */
		STp->drv_write_prot = 0;
	} else {
                DEBC(printk(ST_DEB_MSG
                            "%s: Mode sense. Length %d, medium %x, WBS %x, BLL %d\n",
                            name,
                            (STp->buffer)->b_data[0], (STp->buffer)->b_data[1],
                            (STp->buffer)->b_data[2], (STp->buffer)->b_data[3]));

		if ((STp->buffer)->b_data[3] >= 8) {
			STp->drv_buffer = ((STp->buffer)->b_data[2] >> 4) & 7;
			STp->density = (STp->buffer)->b_data[4];
			STp->block_size = (STp->buffer)->b_data[9] * 65536 +
			    (STp->buffer)->b_data[10] * 256 + (STp->buffer)->b_data[11];
                        DEBC(printk(ST_DEB_MSG
                                    "%s: Density %x, tape length: %x, drv buffer: %d\n",
                                    name, STp->density, (STp->buffer)->b_data[5] * 65536 +
                                    (STp->buffer)->b_data[6] * 256 + (STp->buffer)->b_data[7],
                                    STp->drv_buffer));
		}
		STp->drv_write_prot = ((STp->buffer)->b_data[2] & 0x80) != 0;
		if (!STp->drv_buffer && STp->immediate_filemark) {
			printk(KERN_WARNING
			    "%s: non-buffered tape: disabling writing immediate filemarks\n",
			    name);
			STp->immediate_filemark = 0;
		}
	}
	st_release_request(SRpnt);
	SRpnt = NULL;
        STp->inited = 1;

	if (STp->block_size > 0)
		(STp->buffer)->buffer_blocks =
                        (STp->buffer)->buffer_size / STp->block_size;
	else
		(STp->buffer)->buffer_blocks = 1;
	(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;

        DEBC(printk(ST_DEB_MSG
                       "%s: Block size: %d, buffer size: %d (%d blocks).\n", name,
		       STp->block_size, (STp->buffer)->buffer_size,
		       (STp->buffer)->buffer_blocks));

	if (STp->drv_write_prot) {
		STp->write_prot = 1;

                DEBC(printk(ST_DEB_MSG "%s: Write protected\n", name));

		if (do_wait &&
		    ((st_flags & O_ACCMODE) == O_WRONLY ||
		     (st_flags & O_ACCMODE) == O_RDWR)) {
			retval = (-EROFS);
			goto err_out;
		}
	}

	if (STp->can_partitions && STp->nbr_partitions < 1) {
		/* This code is reached when the device is opened for the first time
		   after the driver has been initialized with tape in the drive and the
		   partition support has been enabled. */
                DEBC(printk(ST_DEB_MSG
                            "%s: Updating partition number in status.\n", name));
		if ((STp->partition = find_partition(STp)) < 0) {
			retval = STp->partition;
			goto err_out;
		}
		STp->new_partition = STp->partition;
		STp->nbr_partitions = 1; /* This guess will be updated when necessary */
	}

	if (new_session) {	/* Change the drive parameters for the new mode */
		STp->density_changed = STp->blksize_changed = 0;
		STp->compression_changed = 0;
		if (!(STm->defaults_for_writes) &&
		    (retval = set_mode_densblk(STp, STm)) < 0)
		    goto err_out;

		if (STp->default_drvbuffer != 0xff) {
			if (st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer))
				printk(KERN_WARNING
                                       "%s: Can't set default drive buffering to %d.\n",
				       name, STp->default_drvbuffer);
		}
	}

	return CHKRES_READY;

 err_out:
	return retval;
}


/* Open the device. Needs to take the BKL only because of incrementing the SCSI host
   module count. */
static int st_open(struct inode *inode, struct file *filp)
{
	int i, retval = (-EIO);
	int resumed = 0;
	struct scsi_tape *STp;
	struct st_partstat *STps;
	int dev = TAPE_NR(inode);
	char *name;

	mutex_lock(&st_mutex);
	/*
	 * We really want to do nonseekable_open(inode, filp); here, but some
	 * versions of tar incorrectly call lseek on tapes and bail out if that
	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
	 */
	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);

	if (!(STp = scsi_tape_get(dev))) {
		mutex_unlock(&st_mutex);
		return -ENXIO;
	}

	write_lock(&st_dev_arr_lock);
	filp->private_data = STp;
	name = tape_name(STp);

	if (STp->in_use) {
		write_unlock(&st_dev_arr_lock);
		scsi_tape_put(STp);
		mutex_unlock(&st_mutex);
		DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
		return (-EBUSY);
	}

	STp->in_use = 1;
	write_unlock(&st_dev_arr_lock);
	STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;

	if (scsi_autopm_get_device(STp->device) < 0) {
		retval = -EIO;
		goto err_out;
	}
	resumed = 1;
	if (!scsi_block_when_processing_errors(STp->device)) {
		retval = (-ENXIO);
		goto err_out;
	}

	/* See that we have at least a one page buffer available */
	if (!enlarge_buffer(STp->buffer, PAGE_SIZE, STp->restr_dma)) {
		printk(KERN_WARNING "%s: Can't allocate one page tape buffer.\n",
		       name);
		retval = (-EOVERFLOW);
		goto err_out;
	}

	(STp->buffer)->cleared = 0;
	(STp->buffer)->writing = 0;
	(STp->buffer)->syscall_result = 0;

	STp->write_prot = ((filp->f_flags & O_ACCMODE) == O_RDONLY);

	STp->dirty = 0;
	for (i = 0; i < ST_NBR_PARTITIONS; i++) {
		STps = &(STp->ps[i]);
		STps->rw = ST_IDLE;
	}
	STp->try_dio_now = STp->try_dio;
	STp->recover_count = 0;
	DEB( STp->nbr_waits = STp->nbr_finished = 0;
	     STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = 0; )

	retval = check_tape(STp, filp);
	if (retval < 0)
		goto err_out;
	if ((filp->f_flags & O_NONBLOCK) == 0 &&
	    retval != CHKRES_READY) {
		if (STp->ready == NO_TAPE)
			retval = (-ENOMEDIUM);
		else
			retval = (-EIO);
		goto err_out;
	}
	mutex_unlock(&st_mutex);
	return 0;

 err_out:
	normalize_buffer(STp->buffer);
	STp->in_use = 0;
	scsi_tape_put(STp);
	if (resumed)
		scsi_autopm_put_device(STp->device);
	mutex_unlock(&st_mutex);
	return retval;

}


/* Flush the tape buffer before close */
static int st_flush(struct file *filp, fl_owner_t id)
{
	int result = 0, result2;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	struct scsi_tape *STp = filp->private_data;
	struct st_modedef *STm = &(STp->modes[STp->current_mode]);
	struct st_partstat *STps = &(STp->ps[STp->partition]);
	char *name = tape_name(STp);

	if (file_count(filp) > 1)
		return 0;

	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
		result = st_flush_write_buffer(STp);
		if (result != 0 && result != (-ENOSPC))
			goto out;
	}

	if (STp->can_partitions &&
	    (result2 = switch_partition(STp)) < 0) {
                DEBC(printk(ST_DEB_MSG
                               "%s: switch_partition at close failed.\n", name));
		if (result == 0)
			result = result2;
		goto out;
	}

	DEBC( if (STp->nbr_requests)
		printk(KERN_DEBUG "%s: Number of r/w requests %d, dio used in %d, pages %d.\n",
		       name, STp->nbr_requests, STp->nbr_dio, STp->nbr_pages));

	if (STps->rw == ST_WRITING && !STp->pos_unknown) {
		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

                DEBC(printk(ST_DEB_MSG "%s: Async write waits %d, finished %d.\n",
                            name, STp->nbr_waits, STp->nbr_finished);
		)

		memset(cmd, 0, MAX_COMMAND_SIZE);
		cmd[0] = WRITE_FILEMARKS;
		if (STp->immediate_filemark)
			cmd[1] = 1;
		cmd[4] = 1 + STp->two_fm;

		SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
				   STp->device->request_queue->rq_timeout,
				   MAX_WRITE_RETRIES, 1);
		if (!SRpnt) {
			result = (STp->buffer)->syscall_result;
			goto out;
		}

		if (STp->buffer->syscall_result == 0 ||
		    (cmdstatp->have_sense && !cmdstatp->deferred &&
		     (cmdstatp->flags & SENSE_EOM) &&
		     (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
		      cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) &&
		     (!cmdstatp->remainder_valid || cmdstatp->uremainder64 == 0))) {
			/* Write successful at EOM */
			st_release_request(SRpnt);
			SRpnt = NULL;
			if (STps->drv_file >= 0)
				STps->drv_file++;
			STps->drv_block = 0;
			if (STp->two_fm)
				cross_eof(STp, 0);
			STps->eof = ST_FM;
		}
		else { /* Write error */
			st_release_request(SRpnt);
			SRpnt = NULL;
			printk(KERN_ERR "%s: Error on write filemark.\n", name);
			if (result == 0)
				result = (-EIO);
		}

                DEBC(printk(ST_DEB_MSG "%s: Buffer flushed, %d EOF(s) written\n",
                            name, cmd[4]));
	} else if (!STp->rew_at_close) {
		STps = &(STp->ps[STp->partition]);
		if (!STm->sysv || STps->rw != ST_READING) {
			if (STp->can_bsr)
				result = flush_buffer(STp, 0);
			else if (STps->eof == ST_FM_HIT) {
				result = cross_eof(STp, 0);
				if (result) {
					if (STps->drv_file >= 0)
						STps->drv_file++;
					STps->drv_block = 0;
					STps->eof = ST_FM;
				} else
					STps->eof = ST_NOEOF;
			}
		} else if ((STps->eof == ST_NOEOF &&
			    !(result = cross_eof(STp, 1))) ||
			   STps->eof == ST_FM_HIT) {
			if (STps->drv_file >= 0)
				STps->drv_file++;
			STps->drv_block = 0;
			STps->eof = ST_FM;
		}
	}

      out:
	if (STp->rew_at_close) {
		result2 = st_int_ioctl(STp, MTREW, 1);
		if (result == 0)
			result = result2;
	}
	return result;
}


/* Close the device and release it. BKL is not needed: this is the only thread
   accessing this tape. */
static int st_release(struct inode *inode, struct file *filp)
{
	int result = 0;
	struct scsi_tape *STp = filp->private_data;

	if (STp->door_locked == ST_LOCKED_AUTO)
		do_door_lock(STp, 0);

	normalize_buffer(STp->buffer);
	write_lock(&st_dev_arr_lock);
	STp->in_use = 0;
	write_unlock(&st_dev_arr_lock);
	scsi_autopm_put_device(STp->device);
	scsi_tape_put(STp);

	return result;
}

/* The checks common to both reading and writing */
static ssize_t rw_checks(struct scsi_tape *STp, struct file *filp, size_t count)
{
	ssize_t retval = 0;

	/*
	 * If we are in the middle of error recovery, don't let anyone
	 * else try and use this device.  Also, if error recovery fails, it
	 * may try and take the device offline, in which case all further
	 * access to the device is prohibited.
	 */
	if (!scsi_block_when_processing_errors(STp->device)) {
		retval = (-ENXIO);
		goto out;
	}

	if (STp->ready != ST_READY) {
		if (STp->ready == ST_NO_TAPE)
			retval = (-ENOMEDIUM);
		else
			retval = (-EIO);
		goto out;
	}

	if (! STp->modes[STp->current_mode].defined) {
		retval = (-ENXIO);
		goto out;
	}


	/*
	 * If there was a bus reset, block further access
	 * to this device.
	 */
	if (STp->pos_unknown) {
		retval = (-EIO);
		goto out;
	}

	if (count == 0)
		goto out;

        DEB(
	if (!STp->in_use) {
		printk(ST_DEB_MSG "%s: Incorrect device.\n", tape_name(STp));
		retval = (-EIO);
		goto out;
	} ) /* end DEB */

	if (STp->can_partitions &&
	    (retval = switch_partition(STp)) < 0)
		goto out;

	if (STp->block_size == 0 && STp->max_block > 0 &&
	    (count < STp->min_block || count > STp->max_block)) {
		retval = (-EINVAL);
		goto out;
	}

	if (STp->do_auto_lock && STp->door_locked == ST_UNLOCKED &&
	    !do_door_lock(STp, 1))
		STp->door_locked = ST_LOCKED_AUTO;

 out:
	return retval;
}


static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
			   size_t count, int is_read)
{
	int i, bufsize, retval = 0;
	struct st_buffer *STbp = STp->buffer;

	if (is_read)
		i = STp->try_dio_now && try_rdio;
	else
		i = STp->try_dio_now && try_wdio;

	if (i && ((unsigned long)buf & queue_dma_alignment(
					STp->device->request_queue)) == 0) {
		i = sgl_map_user_pages(STbp, STbp->use_sg, (unsigned long)buf,
				       count, (is_read ? READ : WRITE));
		if (i > 0) {
			STbp->do_dio = i;
			STbp->buffer_bytes = 0;   /* can be used as transfer counter */
		}
		else
			STbp->do_dio = 0;  /* fall back to buffering with any error */
		STbp->sg_segs = STbp->do_dio;
		DEB(
		     if (STbp->do_dio) {
			STp->nbr_dio++;
			STp->nbr_pages += STbp->do_dio;
		     }
		)
	} else
		STbp->do_dio = 0;
	DEB( STp->nbr_requests++; )

	if (!STbp->do_dio) {
		if (STp->block_size)
			bufsize = STp->block_size > st_fixed_buffer_size ?
				STp->block_size : st_fixed_buffer_size;
		else {
			bufsize = count;
			/* Make sure that data from previous user is not leaked even if
			   HBA does not return correct residual */
			if (is_read && STp->sili && !STbp->cleared)
				clear_buffer(STbp);
		}

		if (bufsize > STbp->buffer_size &&
		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
			printk(KERN_WARNING "%s: Can't allocate %d byte tape buffer.\n",
			       tape_name(STp), bufsize);
			retval = (-EOVERFLOW);
			goto out;
		}
		if (STp->block_size)
			STbp->buffer_blocks = bufsize / STp->block_size;
	}

 out:
	return retval;
}


/* Can be called more than once after each setup_buffer() */
static void release_buffering(struct scsi_tape *STp, int is_read)
{
	struct st_buffer *STbp;

	STbp = STp->buffer;
	if (STbp->do_dio) {
		sgl_unmap_user_pages(STbp, STbp->do_dio, is_read);
		STbp->do_dio = 0;
		STbp->sg_segs = 0;
	}
}


/* Write command */
static ssize_t
st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
{
	ssize_t total;
	ssize_t i, do_count, blks, transfer;
	ssize_t retval;
	int undone, retry_eot = 0, scode;
	int async_write;
	unsigned char cmd[MAX_COMMAND_SIZE];
	const char __user *b_point;
	struct st_request *SRpnt = NULL;
	struct scsi_tape *STp = filp->private_data;
	struct st_modedef *STm;
	struct st_partstat *STps;
	struct st_buffer *STbp;
	char *name = tape_name(STp);

	if (mutex_lock_interruptible(&STp->lock))
		return -ERESTARTSYS;

	retval = rw_checks(STp, filp, count);
	if (retval || count == 0)
		goto out;

	/* Write must be integral number of blocks */
	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
		printk(KERN_WARNING "%s: Write not multiple of tape block size.\n",
		       name);
		retval = (-EINVAL);
		goto out;
	}

	STm = &(STp->modes[STp->current_mode]);
	STps = &(STp->ps[STp->partition]);

	if (STp->write_prot) {
		retval = (-EACCES);
		goto out;
	}


	if (STps->rw == ST_READING) {
		retval = flush_buffer(STp, 0);
		if (retval)
			goto out;
		STps->rw = ST_WRITING;
	} else if (STps->rw != ST_WRITING &&
		   STps->drv_file == 0 && STps->drv_block == 0) {
		if ((retval = set_mode_densblk(STp, STm)) < 0)
			goto out;
		if (STm->default_compression != ST_DONT_TOUCH &&
		    !(STp->compression_changed)) {
			if (st_compression(STp, (STm->default_compression == ST_YES))) {
				printk(KERN_WARNING "%s: Can't set default compression.\n",
				       name);
				if (modes_defined) {
					retval = (-EINVAL);
					goto out;
				}
			}
		}
	}

	STbp = STp->buffer;
	i = write_behind_check(STp);
	if (i) {
		if (i == -ENOSPC)
			STps->eof = ST_EOM_OK;
		else
			STps->eof = ST_EOM_ERROR;
	}

	if (STps->eof == ST_EOM_OK) {
		STps->eof = ST_EOD_1;  /* allow next write */
		retval = (-ENOSPC);
		goto out;
	}
	else if (STps->eof == ST_EOM_ERROR) {
		retval = (-EIO);
		goto out;
	}

	/* Check the buffer readability in cases where copy_user might catch
	   the problems after some tape movement. */
	if (STp->block_size != 0 &&
	    !STbp->do_dio &&
	    (copy_from_user(&i, buf, 1) != 0 ||
	     copy_from_user(&i, buf + count - 1, 1) != 0)) {
		retval = (-EFAULT);
		goto out;
	}

	retval = setup_buffering(STp, buf, count, 0);
	if (retval)
		goto out;

	total = count;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = WRITE_6;
	cmd[1] = (STp->block_size != 0);

	STps->rw = ST_WRITING;

	b_point = buf;
	while (count > 0 && !retry_eot) {

		if (STbp->do_dio) {
			do_count = count;
		}
		else {
			if (STp->block_size == 0)
				do_count = count;
			else {
				do_count = STbp->buffer_blocks * STp->block_size -
					STbp->buffer_bytes;
				if (do_count > count)
					do_count = count;
			}

			i = append_to_buffer(b_point, STbp, do_count);
			if (i) {
				retval = i;
				goto out;
			}
		}
		count -= do_count;
		b_point += do_count;

		async_write = STp->block_size == 0 && !STbp->do_dio &&
			STm->do_async_writes && STps->eof < ST_EOM_OK;

		if (STp->block_size != 0 && STm->do_buffer_writes &&
		    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
		    STbp->buffer_bytes < STbp->buffer_size) {
			STp->dirty = 1;
			/* Don't write a buffer that is not full enough. */
			if (!async_write && count == 0)
				break;
		}

	retry_write:
		if (STp->block_size == 0)
			blks = transfer = do_count;
		else {
			if (!STbp->do_dio)
				blks = STbp->buffer_bytes;
			else
				blks = do_count;
			blks /= STp->block_size;
			transfer = blks * STp->block_size;
		}
		cmd[2] = blks >> 16;
		cmd[3] = blks >> 8;
		cmd[4] = blks;

		SRpnt = st_do_scsi(SRpnt, STp, cmd, transfer, DMA_TO_DEVICE,
				   STp->device->request_queue->rq_timeout,
				   MAX_WRITE_RETRIES, !async_write);
		if (!SRpnt) {
			retval = STbp->syscall_result;
			goto out;
		}
		if (async_write && !STbp->syscall_result) {
			STbp->writing = transfer;
			STp->dirty = !(STbp->writing ==
				       STbp->buffer_bytes);
			SRpnt = NULL;  /* Prevent releasing this request! */
			DEB( STp->write_pending = 1; )
			break;
		}

		if (STbp->syscall_result != 0) {
			struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

                        DEBC(printk(ST_DEB_MSG "%s: Error on write:\n", name));
			if (cmdstatp->have_sense && (cmdstatp->flags & SENSE_EOM)) {
				scode = cmdstatp->sense_hdr.sense_key;
				if (cmdstatp->remainder_valid)
					undone = (int)cmdstatp->uremainder64;
				else if (STp->block_size == 0 &&
					 scode == VOLUME_OVERFLOW)
					undone = transfer;
				else
					undone = 0;
				if (STp->block_size != 0)
					undone *= STp->block_size;
				if (undone <= do_count) {
					/* Only data from this write is not written */
					count += undone;
					b_point -= undone;
					do_count -= undone;
					if (STp->block_size)
						blks = (transfer - undone) / STp->block_size;
					STps->eof = ST_EOM_OK;
					/* Continue in fixed block mode if all written
					   in this request but still something left to write
					   (retval left to zero)
					*/
					if (STp->block_size == 0 ||
					    undone > 0 || count == 0)
						retval = (-ENOSPC); /* EOM within current request */
                                        DEBC(printk(ST_DEB_MSG
                                                       "%s: EOM with %d bytes unwritten.\n",
						       name, (int)count));
				} else {
					/* EOT within data buffered earlier (possible only
					   in fixed block mode without direct i/o) */
					if (!retry_eot && !cmdstatp->deferred &&
					    (scode == NO_SENSE || scode == RECOVERED_ERROR)) {
						move_buffer_data(STp->buffer, transfer - undone);
						retry_eot = 1;
						if (STps->drv_block >= 0) {
							STps->drv_block += (transfer - undone) /
								STp->block_size;
						}
						STps->eof = ST_EOM_OK;
						DEBC(printk(ST_DEB_MSG
							    "%s: Retry write of %d bytes at EOM.\n",
							    name, STp->buffer->buffer_bytes));
						goto retry_write;
					}
					else {
						/* Either error within data buffered by driver or
						   failed retry */
						count -= do_count;
						blks = do_count = 0;
						STps->eof = ST_EOM_ERROR;
						STps->drv_block = (-1); /* Too cautious? */
						retval = (-EIO);	/* EOM for old data */
						DEBC(printk(ST_DEB_MSG
							    "%s: EOM with lost data.\n",
							    name));
					}
				}
			} else {
				count += do_count;
				STps->drv_block = (-1);		/* Too cautious? */
				retval = STbp->syscall_result;
			}

		}

		if (STps->drv_block >= 0) {
			if (STp->block_size == 0)
				STps->drv_block += (do_count > 0);
			else
				STps->drv_block += blks;
		}

		STbp->buffer_bytes = 0;
		STp->dirty = 0;

		if (retval || retry_eot) {
			if (count < total)
				retval = total - count;
			goto out;
		}
	}

	if (STps->eof == ST_EOD_1)
		STps->eof = ST_EOM_OK;
	else if (STps->eof != ST_EOM_OK)
		STps->eof = ST_NOEOF;
	retval = total - count;

 out:
	if (SRpnt != NULL)
		st_release_request(SRpnt);
	release_buffering(STp, 0);
	mutex_unlock(&STp->lock);

	return retval;
}

/* Read data from the tape. Returns zero in the normal case, one if the
   eof status has changed, and the negative error code in case of a
   fatal error. Otherwise updates the buffer and the eof state.

   Does release user buffer mapping if it is set.
*/
static long read_tape(struct scsi_tape *STp, long count,
		      struct st_request ** aSRpnt)
{
	int transfer, blks, bytes;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	struct st_modedef *STm;
	struct st_partstat *STps;
	struct st_buffer *STbp;
	int retval = 0;
	char *name = tape_name(STp);

	if (count == 0)
		return 0;

	STm = &(STp->modes[STp->current_mode]);
	STps = &(STp->ps[STp->partition]);
	if (STps->eof == ST_FM_HIT)
		return 1;
	STbp = STp->buffer;

	if (STp->block_size == 0)
		blks = bytes = count;
	else {
		if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
			blks = (STp->buffer)->buffer_blocks;
			bytes = blks * STp->block_size;
		} else {
			bytes = count;
			if (!STbp->do_dio && bytes > (STp->buffer)->buffer_size)
				bytes = (STp->buffer)->buffer_size;
			blks = bytes / STp->block_size;
			bytes = blks * STp->block_size;
		}
	}

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = READ_6;
	cmd[1] = (STp->block_size != 0);
	if (!cmd[1] && STp->sili)
		cmd[1] |= 2;
	cmd[2] = blks >> 16;
	cmd[3] = blks >> 8;
	cmd[4] = blks;

	SRpnt = *aSRpnt;
	SRpnt = st_do_scsi(SRpnt, STp, cmd, bytes, DMA_FROM_DEVICE,
			   STp->device->request_queue->rq_timeout,
			   MAX_RETRIES, 1);
	release_buffering(STp, 1);
	*aSRpnt = SRpnt;
	if (!SRpnt)
		return STbp->syscall_result;

	STbp->read_pointer = 0;
	STps->at_sm = 0;

	/* Something to check */
	if (STbp->syscall_result) {
		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

		retval = 1;
		DEBC(printk(ST_DEB_MSG "%s: Sense: %2x %2x %2x %2x %2x %2x %2x %2x\n",
                            name,
                            SRpnt->sense[0], SRpnt->sense[1],
                            SRpnt->sense[2], SRpnt->sense[3],
                            SRpnt->sense[4], SRpnt->sense[5],
                            SRpnt->sense[6], SRpnt->sense[7]));
		if (cmdstatp->have_sense) {

			if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
				cmdstatp->flags &= 0xcf;	/* No need for EOM in this case */

			if (cmdstatp->flags != 0) { /* EOF, EOM, or ILI */
				/* Compute the residual count */
				if (cmdstatp->remainder_valid)
					transfer = (int)cmdstatp->uremainder64;
				else
					transfer = 0;
				if (STp->block_size == 0 &&
				    cmdstatp->sense_hdr.sense_key == MEDIUM_ERROR)
					transfer = bytes;

				if (cmdstatp->flags & SENSE_ILI) {	/* ILI */
					if (STp->block_size == 0) {
						if (transfer <= 0) {
							if (transfer < 0)
								printk(KERN_NOTICE
								       "%s: Failed to read %d byte block with %d byte transfer.\n",
								       name, bytes - transfer, bytes);
							if (STps->drv_block >= 0)
								STps->drv_block += 1;
							STbp->buffer_bytes = 0;
							return (-ENOMEM);
						}
						STbp->buffer_bytes = bytes - transfer;
					} else {
						st_release_request(SRpnt);
						SRpnt = *aSRpnt = NULL;
						if (transfer == blks) {	/* We did not get anything, error */
							printk(KERN_NOTICE "%s: Incorrect block size.\n", name);
							if (STps->drv_block >= 0)
								STps->drv_block += blks - transfer + 1;
							st_int_ioctl(STp, MTBSR, 1);
							return (-EIO);
						}
						/* We have some data, deliver it */
						STbp->buffer_bytes = (blks - transfer) *
						    STp->block_size;
                                                DEBC(printk(ST_DEB_MSG
                                                            "%s: ILI but enough data received %ld %d.\n",
                                                            name, count, STbp->buffer_bytes));
						if (STps->drv_block >= 0)
							STps->drv_block += 1;
						if (st_int_ioctl(STp, MTBSR, 1))
							return (-EIO);
					}
				} else if (cmdstatp->flags & SENSE_FMK) {	/* FM overrides EOM */
					if (STps->eof != ST_FM_HIT)
						STps->eof = ST_FM_HIT;
					else
						STps->eof = ST_EOD_2;
					if (STp->block_size == 0)
						STbp->buffer_bytes = 0;
					else
						STbp->buffer_bytes =
						    bytes - transfer * STp->block_size;
                                        DEBC(printk(ST_DEB_MSG
                                                    "%s: EOF detected (%d bytes read).\n",
                                                    name, STbp->buffer_bytes));
				} else if (cmdstatp->flags & SENSE_EOM) {
					if (STps->eof == ST_FM)
						STps->eof = ST_EOD_1;
					else
						STps->eof = ST_EOM_OK;
					if (STp->block_size == 0)
						STbp->buffer_bytes = bytes - transfer;
					else
						STbp->buffer_bytes =
						    bytes - transfer * STp->block_size;

                                        DEBC(printk(ST_DEB_MSG "%s: EOM detected (%d bytes read).\n",
                                                    name, STbp->buffer_bytes));
				}
			}
			/* end of EOF, EOM, ILI test */ 
			else {	/* nonzero sense key */
                                DEBC(printk(ST_DEB_MSG
                                            "%s: Tape error while reading.\n", name));
				STps->drv_block = (-1);
				if (STps->eof == ST_FM &&
				    cmdstatp->sense_hdr.sense_key == BLANK_CHECK) {
                                        DEBC(printk(ST_DEB_MSG
                                                    "%s: Zero returned for first BLANK CHECK after EOF.\n",
                                                    name));
					STps->eof = ST_EOD_2;	/* First BLANK_CHECK after FM */
				} else	/* Some other extended sense code */
					retval = (-EIO);
			}

			if (STbp->buffer_bytes < 0)  /* Caused by bogus sense data */
				STbp->buffer_bytes = 0;
		}
		/* End of extended sense test */ 
		else {		/* Non-extended sense */
			retval = STbp->syscall_result;
		}

	}
	/* End of error handling */ 
	else {			/* Read successful */
		STbp->buffer_bytes = bytes;
		if (STp->sili) /* In fixed block mode residual is always zero here */
			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
	}

	if (STps->drv_block >= 0) {
		if (STp->block_size == 0)
			STps->drv_block++;
		else
			STps->drv_block += STbp->buffer_bytes / STp->block_size;
	}
	return retval;
}


/* Read command */
static ssize_t
st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
{
	ssize_t total;
	ssize_t retval = 0;
	ssize_t i, transfer;
	int special, do_dio = 0;
	struct st_request *SRpnt = NULL;
	struct scsi_tape *STp = filp->private_data;
	struct st_modedef *STm;
	struct st_partstat *STps;
	struct st_buffer *STbp = STp->buffer;
	DEB( char *name = tape_name(STp); )

	if (mutex_lock_interruptible(&STp->lock))
		return -ERESTARTSYS;

	retval = rw_checks(STp, filp, count);
	if (retval || count == 0)
		goto out;

	STm = &(STp->modes[STp->current_mode]);
	if (STp->block_size != 0 && (count % STp->block_size) != 0) {
		if (!STm->do_read_ahead) {
			retval = (-EINVAL);	/* Read must be integral number of blocks */
			goto out;
		}
		STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
	}

	STps = &(STp->ps[STp->partition]);
	if (STps->rw == ST_WRITING) {
		retval = flush_buffer(STp, 0);
		if (retval)
			goto out;
		STps->rw = ST_READING;
	}
        DEB(
	if (debugging && STps->eof != ST_NOEOF)
		printk(ST_DEB_MSG "%s: EOF/EOM flag up (%d). Bytes %d\n", name,
		       STps->eof, STbp->buffer_bytes);
        ) /* end DEB */

	retval = setup_buffering(STp, buf, count, 1);
	if (retval)
		goto out;
	do_dio = STbp->do_dio;

	if (STbp->buffer_bytes == 0 &&
	    STps->eof >= ST_EOD_1) {
		if (STps->eof < ST_EOD) {
			STps->eof += 1;
			retval = 0;
			goto out;
		}
		retval = (-EIO);	/* EOM or Blank Check */
		goto out;
	}

	if (do_dio) {
		/* Check the buffer writability before any tape movement. Don't alter
		   buffer data. */
		if (copy_from_user(&i, buf, 1) != 0 ||
		    copy_to_user(buf, &i, 1) != 0 ||
		    copy_from_user(&i, buf + count - 1, 1) != 0 ||
		    copy_to_user(buf + count - 1, &i, 1) != 0) {
			retval = (-EFAULT);
			goto out;
		}
	}

	STps->rw = ST_READING;


	/* Loop until enough data in buffer or a special condition found */
	for (total = 0, special = 0; total < count && !special;) {

		/* Get new data if the buffer is empty */
		if (STbp->buffer_bytes == 0) {
			special = read_tape(STp, count - total, &SRpnt);
			if (special < 0) {	/* No need to continue read */
				retval = special;
				goto out;
			}
		}

		/* Move the data from driver buffer to user buffer */
		if (STbp->buffer_bytes > 0) {
                        DEB(
			if (debugging && STps->eof != ST_NOEOF)
				printk(ST_DEB_MSG
                                       "%s: EOF up (%d). Left %d, needed %d.\n", name,
				       STps->eof, STbp->buffer_bytes,
                                       (int)(count - total));
                        ) /* end DEB */
			transfer = STbp->buffer_bytes < count - total ?
			    STbp->buffer_bytes : count - total;
			if (!do_dio) {
				i = from_buffer(STbp, buf, transfer);
				if (i) {
					retval = i;
					goto out;
				}
			}
			buf += transfer;
			total += transfer;
		}

		if (STp->block_size == 0)
			break;	/* Read only one variable length block */

	}			/* for (total = 0, special = 0;
                                   total < count && !special; ) */

	/* Change the eof state if no data from tape or buffer */
	if (total == 0) {
		if (STps->eof == ST_FM_HIT) {
			STps->eof = ST_FM;
			STps->drv_block = 0;
			if (STps->drv_file >= 0)
				STps->drv_file++;
		} else if (STps->eof == ST_EOD_1) {
			STps->eof = ST_EOD_2;
			STps->drv_block = 0;
			if (STps->drv_file >= 0)
				STps->drv_file++;
		} else if (STps->eof == ST_EOD_2)
			STps->eof = ST_EOD;
	} else if (STps->eof == ST_FM)
		STps->eof = ST_NOEOF;
	retval = total;

 out:
	if (SRpnt != NULL) {
		st_release_request(SRpnt);
		SRpnt = NULL;
	}
	if (do_dio) {
		release_buffering(STp, 1);
		STbp->buffer_bytes = 0;
	}
	mutex_unlock(&STp->lock);

	return retval;
}



DEB(
/* Set the driver options */
static void st_log_options(struct scsi_tape * STp, struct st_modedef * STm, char *name)
{
	if (debugging) {
		printk(KERN_INFO
		       "%s: Mode %d options: buffer writes: %d, async writes: %d, read ahead: %d\n",
		       name, STp->current_mode, STm->do_buffer_writes, STm->do_async_writes,
		       STm->do_read_ahead);
		printk(KERN_INFO
		       "%s:    can bsr: %d, two FMs: %d, fast mteom: %d, auto lock: %d,\n",
		       name, STp->can_bsr, STp->two_fm, STp->fast_mteom, STp->do_auto_lock);
		printk(KERN_INFO
		       "%s:    defs for wr: %d, no block limits: %d, partitions: %d, s2 log: %d\n",
		       name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
		       STp->scsi2_logical);
		printk(KERN_INFO
		       "%s:    sysv: %d nowait: %d sili: %d nowait_filemark: %d\n",
		       name, STm->sysv, STp->immediate, STp->sili,
		       STp->immediate_filemark);
		printk(KERN_INFO "%s:    debugging: %d\n",
		       name, debugging);
	}
}
	)


static int st_set_options(struct scsi_tape *STp, long options)
{
	int value;
	long code;
	struct st_modedef *STm;
	char *name = tape_name(STp);
	struct cdev *cd0, *cd1;

	STm = &(STp->modes[STp->current_mode]);
	if (!STm->defined) {
		cd0 = STm->cdevs[0]; cd1 = STm->cdevs[1];
		memcpy(STm, &(STp->modes[0]), sizeof(struct st_modedef));
		STm->cdevs[0] = cd0; STm->cdevs[1] = cd1;
		modes_defined = 1;
                DEBC(printk(ST_DEB_MSG
                            "%s: Initialized mode %d definition from mode 0\n",
                            name, STp->current_mode));
	}

	code = options & MT_ST_OPTIONS;
	if (code == MT_ST_BOOLEANS) {
		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
		if ((STp->device)->scsi_level >= SCSI_2)
			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
		STp->immediate = (options & MT_ST_NOWAIT) != 0;
		STp->immediate_filemark = (options & MT_ST_NOWAIT_EOF) != 0;
		STm->sysv = (options & MT_ST_SYSV) != 0;
		STp->sili = (options & MT_ST_SILI) != 0;
		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
		     st_log_options(STp, STm, name); )
	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
		value = (code == MT_ST_SETBOOLEANS);
		if ((options & MT_ST_BUFFER_WRITES) != 0)
			STm->do_buffer_writes = value;
		if ((options & MT_ST_ASYNC_WRITES) != 0)
			STm->do_async_writes = value;
		if ((options & MT_ST_DEF_WRITES) != 0)
			STm->defaults_for_writes = value;
		if ((options & MT_ST_READ_AHEAD) != 0)
			STm->do_read_ahead = value;
		if ((options & MT_ST_TWO_FM) != 0)
			STp->two_fm = value;
		if ((options & MT_ST_FAST_MTEOM) != 0)
			STp->fast_mteom = value;
		if ((options & MT_ST_AUTO_LOCK) != 0)
			STp->do_auto_lock = value;
		if ((options & MT_ST_CAN_BSR) != 0)
			STp->can_bsr = value;
		if ((options & MT_ST_NO_BLKLIMS) != 0)
			STp->omit_blklims = value;
		if ((STp->device)->scsi_level >= SCSI_2 &&
		    (options & MT_ST_CAN_PARTITIONS) != 0)
			STp->can_partitions = value;
		if ((options & MT_ST_SCSI2LOGICAL) != 0)
			STp->scsi2_logical = value;
		if ((options & MT_ST_NOWAIT) != 0)
			STp->immediate = value;
		if ((options & MT_ST_NOWAIT_EOF) != 0)
			STp->immediate_filemark = value;
		if ((options & MT_ST_SYSV) != 0)
			STm->sysv = value;
		if ((options & MT_ST_SILI) != 0)
			STp->sili = value;
                DEB(
		if ((options & MT_ST_DEBUGGING) != 0)
			debugging = value;
			st_log_options(STp, STm, name); )
	} else if (code == MT_ST_WRITE_THRESHOLD) {
		/* Retained for compatibility */
	} else if (code == MT_ST_DEF_BLKSIZE) {
		value = (options & ~MT_ST_OPTIONS);
		if (value == ~MT_ST_OPTIONS) {
			STm->default_blksize = (-1);
			DEBC( printk(KERN_INFO "%s: Default block size disabled.\n", name));
		} else {
			STm->default_blksize = value;
			DEBC( printk(KERN_INFO "%s: Default block size set to %d bytes.\n",
			       name, STm->default_blksize));
			if (STp->ready == ST_READY) {
				STp->blksize_changed = 0;
				set_mode_densblk(STp, STm);
			}
		}
	} else if (code == MT_ST_TIMEOUTS) {
		value = (options & ~MT_ST_OPTIONS);
		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
			DEBC( printk(KERN_INFO "%s: Long timeout set to %d seconds.\n", name,
			       (value & ~MT_ST_SET_LONG_TIMEOUT)));
		} else {
			blk_queue_rq_timeout(STp->device->request_queue,
					     value * HZ);
			DEBC( printk(KERN_INFO "%s: Normal timeout set to %d seconds.\n",
				name, value) );
		}
	} else if (code == MT_ST_SET_CLN) {
		value = (options & ~MT_ST_OPTIONS) & 0xff;
		if (value != 0 &&
			(value < EXTENDED_SENSE_START ||
				value >= SCSI_SENSE_BUFFERSIZE))
			return (-EINVAL);
		STp->cln_mode = value;
		STp->cln_sense_mask = (options >> 8) & 0xff;
		STp->cln_sense_value = (options >> 16) & 0xff;
		printk(KERN_INFO
		       "%s: Cleaning request mode %d, mask %02x, value %02x\n",
		       name, value, STp->cln_sense_mask, STp->cln_sense_value);
	} else if (code == MT_ST_DEF_OPTIONS) {
		code = (options & ~MT_ST_CLEAR_DEFAULT);
		value = (options & MT_ST_CLEAR_DEFAULT);
		if (code == MT_ST_DEF_DENSITY) {
			if (value == MT_ST_CLEAR_DEFAULT) {
				STm->default_density = (-1);
				DEBC( printk(KERN_INFO "%s: Density default disabled.\n",
                                       name));
			} else {
				STm->default_density = value & 0xff;
				DEBC( printk(KERN_INFO "%s: Density default set to %x\n",
				       name, STm->default_density));
				if (STp->ready == ST_READY) {
					STp->density_changed = 0;
					set_mode_densblk(STp, STm);
				}
			}
		} else if (code == MT_ST_DEF_DRVBUFFER) {
			if (value == MT_ST_CLEAR_DEFAULT) {
				STp->default_drvbuffer = 0xff;
				DEBC( printk(KERN_INFO
                                       "%s: Drive buffer default disabled.\n", name));
			} else {
				STp->default_drvbuffer = value & 7;
				DEBC( printk(KERN_INFO
                                       "%s: Drive buffer default set to %x\n",
				       name, STp->default_drvbuffer));
				if (STp->ready == ST_READY)
					st_int_ioctl(STp, MTSETDRVBUFFER, STp->default_drvbuffer);
			}
		} else if (code == MT_ST_DEF_COMPRESSION) {
			if (value == MT_ST_CLEAR_DEFAULT) {
				STm->default_compression = ST_DONT_TOUCH;
				DEBC( printk(KERN_INFO
                                       "%s: Compression default disabled.\n", name));
			} else {
				if ((value & 0xff00) != 0) {
					STp->c_algo = (value & 0xff00) >> 8;
					DEBC( printk(KERN_INFO "%s: Compression algorithm set to 0x%x.\n",
					       name, STp->c_algo));
				}
				if ((value & 0xff) != 0xff) {
					STm->default_compression = (value & 1 ? ST_YES : ST_NO);
					DEBC( printk(KERN_INFO "%s: Compression default set to %x\n",
					       name, (value & 1)));
					if (STp->ready == ST_READY) {
						STp->compression_changed = 0;
						st_compression(STp, (STm->default_compression == ST_YES));
					}
				}
			}
		}
	} else
		return (-EIO);

	return 0;
}

#define MODE_HEADER_LENGTH  4

/* Mode header and page byte offsets */
#define MH_OFF_DATA_LENGTH     0
#define MH_OFF_MEDIUM_TYPE     1
#define MH_OFF_DEV_SPECIFIC    2
#define MH_OFF_BDESCS_LENGTH   3
#define MP_OFF_PAGE_NBR        0
#define MP_OFF_PAGE_LENGTH     1

/* Mode header and page bit masks */
#define MH_BIT_WP              0x80
#define MP_MSK_PAGE_NBR        0x3f

/* Don't return block descriptors */
#define MODE_SENSE_OMIT_BDESCS 0x08

#define MODE_SELECT_PAGE_FORMAT 0x10

/* Read a mode page into the tape buffer. The block descriptors are included
   if incl_block_descs is true. The page control is ored to the page number
   parameter, if necessary. */
static int read_mode_page(struct scsi_tape *STp, int page, int omit_block_descs)
{
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = MODE_SENSE;
	if (omit_block_descs)
		cmd[1] = MODE_SENSE_OMIT_BDESCS;
	cmd[2] = page;
	cmd[4] = 255;

	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_FROM_DEVICE,
			   STp->device->request_queue->rq_timeout, 0, 1);
	if (SRpnt == NULL)
		return (STp->buffer)->syscall_result;

	st_release_request(SRpnt);

	return STp->buffer->syscall_result;
}


/* Send the mode page in the tape buffer to the drive. Assumes that the mode data
   in the buffer is correctly formatted. The long timeout is used if slow is non-zero. */
static int write_mode_page(struct scsi_tape *STp, int page, int slow)
{
	int pgo;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	int timeout;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = MODE_SELECT;
	cmd[1] = MODE_SELECT_PAGE_FORMAT;
	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;

	/* Clear reserved fields */
	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;

	timeout = slow ?
		STp->long_timeout : STp->device->request_queue->rq_timeout;
	SRpnt = st_do_scsi(NULL, STp, cmd, cmd[4], DMA_TO_DEVICE,
			   timeout, 0, 1);
	if (SRpnt == NULL)
		return (STp->buffer)->syscall_result;

	st_release_request(SRpnt);

	return STp->buffer->syscall_result;
}


#define COMPRESSION_PAGE        0x0f
#define COMPRESSION_PAGE_LENGTH 16

#define CP_OFF_DCE_DCC          2
#define CP_OFF_C_ALGO           7

#define DCE_MASK  0x80
#define DCC_MASK  0x40
#define RED_MASK  0x60


/* Control the compression with mode page 15. Algorithm not changed if zero.

   The block descriptors are read and written because Sony SDT-7000 does not
   work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).
   Including block descriptors should not cause any harm to other drives. */

static int st_compression(struct scsi_tape * STp, int state)
{
	int retval;
	int mpoffs;  /* Offset to mode page start */
	unsigned char *b_data = (STp->buffer)->b_data;
	DEB( char *name = tape_name(STp); )

	if (STp->ready != ST_READY)
		return (-EIO);

	/* Read the current page contents */
	retval = read_mode_page(STp, COMPRESSION_PAGE, 0);
	if (retval) {
                DEBC(printk(ST_DEB_MSG "%s: Compression mode page not supported.\n",
                            name));
		return (-EIO);
	}

	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
        DEBC(printk(ST_DEB_MSG "%s: Compression state is %d.\n", name,
                    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0)));

	/* Check if compression can be changed */
	if ((b_data[mpoffs + CP_OFF_DCE_DCC] & DCC_MASK) == 0) {
                DEBC(printk(ST_DEB_MSG "%s: Compression not supported.\n", name));
		return (-EIO);
	}

	/* Do the change */
	if (state) {
		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
		if (STp->c_algo != 0)
			b_data[mpoffs + CP_OFF_C_ALGO] = STp->c_algo;
	}
	else {
		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;
		if (STp->c_algo != 0)
			b_data[mpoffs + CP_OFF_C_ALGO] = 0; /* no compression */
	}

	retval = write_mode_page(STp, COMPRESSION_PAGE, 0);
	if (retval) {
                DEBC(printk(ST_DEB_MSG "%s: Compression change failed.\n", name));
		return (-EIO);
	}
        DEBC(printk(ST_DEB_MSG "%s: Compression state changed to %d.\n",
		       name, state));

	STp->compression_changed = 1;
	return 0;
}


/* Process the load and unload commands (does unload if the load code is zero) */
static int do_load_unload(struct scsi_tape *STp, struct file *filp, int load_code)
{
	int retval = (-EIO), timeout;
	DEB( char *name = tape_name(STp); )
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_partstat *STps;
	struct st_request *SRpnt;

	if (STp->ready != ST_READY && !load_code) {
		if (STp->ready == ST_NO_TAPE)
			return (-ENOMEDIUM);
		else
			return (-EIO);
	}

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = START_STOP;
	if (load_code)
		cmd[4] |= 1;
	/*
	 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
	 */
	if (load_code >= 1 + MT_ST_HPLOADER_OFFSET
	    && load_code <= 6 + MT_ST_HPLOADER_OFFSET) {
		DEBC(printk(ST_DEB_MSG "%s: Enhanced %sload slot %2d.\n",
			    name, (cmd[4]) ? "" : "un",
			    load_code - MT_ST_HPLOADER_OFFSET));
		cmd[3] = load_code - MT_ST_HPLOADER_OFFSET; /* MediaID field of C1553A */
	}
	if (STp->immediate) {
		cmd[1] = 1;	/* Don't wait for completion */
		timeout = STp->device->request_queue->rq_timeout;
	}
	else
		timeout = STp->long_timeout;

	DEBC(
		if (!load_code)
		printk(ST_DEB_MSG "%s: Unloading tape.\n", name);
		else
		printk(ST_DEB_MSG "%s: Loading tape.\n", name);
		);

	SRpnt = st_do_scsi(NULL, STp, cmd, 0, DMA_NONE,
			   timeout, MAX_RETRIES, 1);
	if (!SRpnt)
		return (STp->buffer)->syscall_result;

	retval = (STp->buffer)->syscall_result;
	st_release_request(SRpnt);

	if (!retval) {	/* SCSI command successful */

		if (!load_code) {
			STp->rew_at_close = 0;
			STp->ready = ST_NO_TAPE;
		}
		else {
			STp->rew_at_close = STp->autorew_dev;
			retval = check_tape(STp, filp);
			if (retval > 0)
				retval = 0;
		}
	}
	else {
		STps = &(STp->ps[STp->partition]);
		STps->drv_file = STps->drv_block = (-1);
	}

	return retval;
}

#if DEBUG
#define ST_DEB_FORWARD  0
#define ST_DEB_BACKWARD 1
static void deb_space_print(char *name, int direction, char *units, unsigned char *cmd)
{
	s32 sc;

	sc = cmd[2] & 0x80 ? 0xff000000 : 0;
	sc |= (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
	if (direction)
		sc = -sc;
	printk(ST_DEB_MSG "%s: Spacing tape %s over %d %s.\n", name,
	       direction ? "backward" : "forward", sc, units);
}
#endif


/* Internal ioctl function */
static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned long arg)
{
	int timeout;
	long ltmp;
	int ioctl_result;
	int chg_eof = 1;
	unsigned char cmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	struct st_partstat *STps;
	int fileno, blkno, at_sm, undone;
	int datalen = 0, direction = DMA_NONE;
	char *name = tape_name(STp);

	WARN_ON(STp->buffer->do_dio != 0);
	if (STp->ready != ST_READY) {
		if (STp->ready == ST_NO_TAPE)
			return (-ENOMEDIUM);
		else
			return (-EIO);
	}
	timeout = STp->long_timeout;
	STps = &(STp->ps[STp->partition]);
	fileno = STps->drv_file;
	blkno = STps->drv_block;
	at_sm = STps->at_sm;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	switch (cmd_in) {
	case MTFSFM:
		chg_eof = 0;	/* Changed from the FSF after this */
	case MTFSF:
		cmd[0] = SPACE;
		cmd[1] = 0x01;	/* Space FileMarks */
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
                DEBC(deb_space_print(name, ST_DEB_FORWARD, "filemarks", cmd);)
		if (fileno >= 0)
			fileno += arg;
		blkno = 0;
		at_sm &= (arg == 0);
		break;
	case MTBSFM:
		chg_eof = 0;	/* Changed from the FSF after this */
	case MTBSF:
		cmd[0] = SPACE;
		cmd[1] = 0x01;	/* Space FileMarks */
		ltmp = (-arg);
		cmd[2] = (ltmp >> 16);
		cmd[3] = (ltmp >> 8);
		cmd[4] = ltmp;
                DEBC(deb_space_print(name, ST_DEB_BACKWARD, "filemarks", cmd);)
		if (fileno >= 0)
			fileno -= arg;
		blkno = (-1);	/* We can't know the block number */
		at_sm &= (arg == 0);
		break;
	case MTFSR:
		cmd[0] = SPACE;
		cmd[1] = 0x00;	/* Space Blocks */
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
                DEBC(deb_space_print(name, ST_DEB_FORWARD, "blocks", cmd);)
		if (blkno >= 0)
			blkno += arg;
		at_sm &= (arg == 0);
		break;
	case MTBSR:
		cmd[0] = SPACE;
		cmd[1] = 0x00;	/* Space Blocks */
		ltmp = (-arg);
		cmd[2] = (ltmp >> 16);
		cmd[3] = (ltmp >> 8);
		cmd[4] = ltmp;
                DEBC(deb_space_print(name, ST_DEB_BACKWARD, "blocks", cmd);)
		if (blkno >= 0)
			blkno -= arg;
		at_sm &= (arg == 0);
		break;
	case MTFSS:
		cmd[0] = SPACE;
		cmd[1] = 0x04;	/* Space Setmarks */
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
                DEBC(deb_space_print(name, ST_DEB_FORWARD, "setmarks", cmd);)
		if (arg != 0) {
			blkno = fileno = (-1);
			at_sm = 1;
		}
		break;
	case MTBSS:
		cmd[0] = SPACE;
		cmd[1] = 0x04;	/* Space Setmarks */
		ltmp = (-arg);
		cmd[2] = (ltmp >> 16);
		cmd[3] = (ltmp >> 8);
		cmd[4] = ltmp;
                DEBC(deb_space_print(name, ST_DEB_BACKWARD, "setmarks", cmd);)
		if (arg != 0) {
			blkno = fileno = (-1);
			at_sm = 1;
		}
		break;
	case MTWEOF:
	case MTWEOFI:
	case MTWSM:
		if (STp->write_prot)
			return (-EACCES);
		cmd[0] = WRITE_FILEMARKS;
		if (cmd_in == MTWSM)
			cmd[1] = 2;
		if (cmd_in == MTWEOFI ||
		    (cmd_in == MTWEOF && STp->immediate_filemark))
			cmd[1] |= 1;
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
		timeout = STp->device->request_queue->rq_timeout;
                DEBC(
		     if (cmd_in != MTWSM)
                               printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name,
				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
                     else
				printk(ST_DEB_MSG "%s: Writing %d setmarks.\n", name,
				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
		)
		if (fileno >= 0)
			fileno += arg;
		blkno = 0;
		at_sm = (cmd_in == MTWSM);
		break;
	case MTREW:
		cmd[0] = REZERO_UNIT;
		if (STp->immediate) {
			cmd[1] = 1;	/* Don't wait for completion */
			timeout = STp->device->request_queue->rq_timeout;
		}
                DEBC(printk(ST_DEB_MSG "%s: Rewinding tape.\n", name));
		fileno = blkno = at_sm = 0;
		break;
	case MTNOP:
                DEBC(printk(ST_DEB_MSG "%s: No op on tape.\n", name));
		return 0;	/* Should do something ? */
		break;
	case MTRETEN:
		cmd[0] = START_STOP;
		if (STp->immediate) {
			cmd[1] = 1;	/* Don't wait for completion */
			timeout = STp->device->request_queue->rq_timeout;
		}
		cmd[4] = 3;
                DEBC(printk(ST_DEB_MSG "%s: Retensioning tape.\n", name));
		fileno = blkno = at_sm = 0;
		break;
	case MTEOM:
		if (!STp->fast_mteom) {
			/* space to the end of tape */
			ioctl_result = st_int_ioctl(STp, MTFSF, 0x7fffff);
			fileno = STps->drv_file;
			if (STps->eof >= ST_EOD_1)
				return 0;
			/* The next lines would hide the number of spaced FileMarks
			   That's why I inserted the previous lines. I had no luck
			   with detecting EOM with FSF, so we go now to EOM.
			   Joerg Weule */
		} else
			fileno = (-1);
		cmd[0] = SPACE;
		cmd[1] = 3;
                DEBC(printk(ST_DEB_MSG "%s: Spacing to end of recorded medium.\n",
                            name));
		blkno = -1;
		at_sm = 0;
		break;
	case MTERASE:
		if (STp->write_prot)
			return (-EACCES);
		cmd[0] = ERASE;
		cmd[1] = (arg ? 1 : 0);	/* Long erase with non-zero argument */
		if (STp->immediate) {
			cmd[1] |= 2;	/* Don't wait for completion */
			timeout = STp->device->request_queue->rq_timeout;
		}
		else
			timeout = STp->long_timeout * 8;

                DEBC(printk(ST_DEB_MSG "%s: Erasing tape.\n", name));
		fileno = blkno = at_sm = 0;
		break;
	case MTSETBLK:		/* Set block length */
	case MTSETDENSITY:	/* Set tape density */
	case MTSETDRVBUFFER:	/* Set drive buffering */
	case SET_DENS_AND_BLK:	/* Set density and block size */
		chg_eof = 0;
		if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
			return (-EIO);	/* Not allowed if data in buffer */
		if ((cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) &&
		    (arg & MT_ST_BLKSIZE_MASK) != 0 &&
		    STp->max_block > 0 &&
		    ((arg & MT_ST_BLKSIZE_MASK) < STp->min_block ||
		     (arg & MT_ST_BLKSIZE_MASK) > STp->max_block)) {
			printk(KERN_WARNING "%s: Illegal block size.\n", name);
			return (-EINVAL);
		}
		cmd[0] = MODE_SELECT;
		if ((STp->use_pf & USE_PF))
			cmd[1] = MODE_SELECT_PAGE_FORMAT;
		cmd[4] = datalen = 12;
		direction = DMA_TO_DEVICE;

		memset((STp->buffer)->b_data, 0, 12);
		if (cmd_in == MTSETDRVBUFFER)
			(STp->buffer)->b_data[2] = (arg & 7) << 4;
		else
			(STp->buffer)->b_data[2] =
			    STp->drv_buffer << 4;
		(STp->buffer)->b_data[3] = 8;	/* block descriptor length */
		if (cmd_in == MTSETDENSITY) {
			(STp->buffer)->b_data[4] = arg;
			STp->density_changed = 1;	/* At least we tried ;-) */
		} else if (cmd_in == SET_DENS_AND_BLK)
			(STp->buffer)->b_data[4] = arg >> 24;
		else
			(STp->buffer)->b_data[4] = STp->density;
		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
			ltmp = arg & MT_ST_BLKSIZE_MASK;
			if (cmd_in == MTSETBLK)
				STp->blksize_changed = 1; /* At least we tried ;-) */
		} else
			ltmp = STp->block_size;
		(STp->buffer)->b_data[9] = (ltmp >> 16);
		(STp->buffer)->b_data[10] = (ltmp >> 8);
		(STp->buffer)->b_data[11] = ltmp;
		timeout = STp->device->request_queue->rq_timeout;
                DEBC(
			if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK)
				printk(ST_DEB_MSG
                                       "%s: Setting block size to %d bytes.\n", name,
				       (STp->buffer)->b_data[9] * 65536 +
				       (STp->buffer)->b_data[10] * 256 +
				       (STp->buffer)->b_data[11]);
			if (cmd_in == MTSETDENSITY || cmd_in == SET_DENS_AND_BLK)
				printk(ST_DEB_MSG
                                       "%s: Setting density code to %x.\n", name,
				       (STp->buffer)->b_data[4]);
			if (cmd_in == MTSETDRVBUFFER)
				printk(ST_DEB_MSG
                                       "%s: Setting drive buffer code to %d.\n", name,
				    ((STp->buffer)->b_data[2] >> 4) & 7);
		)
		break;
	default:
		return (-ENOSYS);
	}

	SRpnt = st_do_scsi(NULL, STp, cmd, datalen, direction,
			   timeout, MAX_RETRIES, 1);
	if (!SRpnt)
		return (STp->buffer)->syscall_result;

	ioctl_result = (STp->buffer)->syscall_result;

	if (!ioctl_result) {	/* SCSI command successful */
		st_release_request(SRpnt);
		SRpnt = NULL;
		STps->drv_block = blkno;
		STps->drv_file = fileno;
		STps->at_sm = at_sm;

		if (cmd_in == MTBSFM)
			ioctl_result = st_int_ioctl(STp, MTFSF, 1);
		else if (cmd_in == MTFSFM)
			ioctl_result = st_int_ioctl(STp, MTBSF, 1);

		if (cmd_in == MTSETBLK || cmd_in == SET_DENS_AND_BLK) {
			STp->block_size = arg & MT_ST_BLKSIZE_MASK;
			if (STp->block_size != 0) {
				(STp->buffer)->buffer_blocks =
				    (STp->buffer)->buffer_size / STp->block_size;
			}
			(STp->buffer)->buffer_bytes = (STp->buffer)->read_pointer = 0;
			if (cmd_in == SET_DENS_AND_BLK)
				STp->density = arg >> MT_ST_DENSITY_SHIFT;
		} else if (cmd_in == MTSETDRVBUFFER)
			STp->drv_buffer = (arg & 7);
		else if (cmd_in == MTSETDENSITY)
			STp->density = arg;

		if (cmd_in == MTEOM)
			STps->eof = ST_EOD;
		else if (cmd_in == MTFSF)
			STps->eof = ST_FM;
		else if (chg_eof)
			STps->eof = ST_NOEOF;

		if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
			STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
	} else { /* SCSI command was not completely successful. Don't return
                    from this block without releasing the SCSI command block! */
		struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;

		if (cmdstatp->flags & SENSE_EOM) {
			if (cmd_in != MTBSF && cmd_in != MTBSFM &&
			    cmd_in != MTBSR && cmd_in != MTBSS)
				STps->eof = ST_EOM_OK;
			STps->drv_block = 0;
		}

		if (cmdstatp->remainder_valid)
			undone = (int)cmdstatp->uremainder64;
		else
			undone = 0;

		if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
		    cmdstatp->have_sense &&
		    (cmdstatp->flags & SENSE_EOM)) {
			if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||
			    cmdstatp->sense_hdr.sense_key == RECOVERED_ERROR) {
				ioctl_result = 0;	/* EOF(s) written successfully at EOM */
				STps->eof = ST_NOEOF;
			} else {  /* Writing EOF(s) failed */
				if (fileno >= 0)
					fileno -= undone;
				if (undone < arg)
					STps->eof = ST_NOEOF;
			}
			STps->drv_file = fileno;
		} else if ((cmd_in == MTFSF) || (cmd_in == MTFSFM)) {
			if (fileno >= 0)
				STps->drv_file = fileno - undone;
			else
				STps->drv_file = fileno;
			STps->drv_block = -1;
			STps->eof = ST_NOEOF;
		} else if ((cmd_in == MTBSF) || (cmd_in == MTBSFM)) {
			if (arg > 0 && undone < 0)  /* Some drives get this wrong */
				undone = (-undone);
			if (STps->drv_file >= 0)
				STps->drv_file = fileno + undone;
			STps->drv_block = 0;
			STps->eof = ST_NOEOF;
		} else if (cmd_in == MTFSR) {
			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
				if (STps->drv_file >= 0)
					STps->drv_file++;
				STps->drv_block = 0;
				STps->eof = ST_FM;
			} else {
				if (blkno >= undone)
					STps->drv_block = blkno - undone;
				else
					STps->drv_block = (-1);
				STps->eof = ST_NOEOF;
			}
		} else if (cmd_in == MTBSR) {
			if (cmdstatp->flags & SENSE_FMK) {	/* Hit filemark */
				STps->drv_file--;
				STps->drv_block = (-1);
			} else {
				if (arg > 0 && undone < 0)  /* Some drives get this wrong */
					undone = (-undone);
				if (STps->drv_block >= 0)
					STps->drv_block = blkno + undone;
			}
			STps->eof = ST_NOEOF;
		} else if (cmd_in == MTEOM) {
			STps->drv_file = (-1);
			STps->drv_block = (-1);
			STps->eof = ST_EOD;
		} else if (cmd_in == MTSETBLK ||
			   cmd_in == MTSETDENSITY ||
			   cmd_in == MTSETDRVBUFFER ||
			   cmd_in == SET_DENS_AND_BLK) {
			if (cmdstatp->sense_hdr.sense_key == ILLEGAL_REQUEST &&
			    !(STp->use_pf & PF_TESTED)) {
				/* Try the other possible state of Page Format if not
				   already tried */
				STp->use_pf = (STp->use_pf ^ USE_PF) | PF_TESTED;
				st_release_request(SRpnt);
				SRpnt = NULL;
				return st_int_ioctl(STp, cmd_in, arg);
			}
		} else if (chg_eof)
			STps->eof = ST_NOEOF;

		if (cmdstatp->sense_hdr.sense_key == BLANK_CHECK)
			STps->eof = ST_EOD;

		st_release_request(SRpnt);
		SRpnt = NULL;
	}

	return ioctl_result;
}


/* Get the tape position. If bt == 2, arg points into a kernel space mt_loc
   structure. */

static int get_location(struct scsi_tape *STp, unsigned int *block, int *partition,
			int logical)
{
	int result;
	unsigned char scmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	DEB( char *name = tape_name(STp); )

	if (STp->ready != ST_READY)
		return (-EIO);

	memset(scmd, 0, MAX_COMMAND_SIZE);
	if ((STp->device)->scsi_level < SCSI_2) {
		scmd[0] = QFA_REQUEST_BLOCK;
		scmd[4] = 3;
	} else {
		scmd[0] = READ_POSITION;
		if (!logical && !STp->scsi2_logical)
			scmd[1] = 1;
	}
	SRpnt = st_do_scsi(NULL, STp, scmd, 20, DMA_FROM_DEVICE,
			   STp->device->request_queue->rq_timeout,
			   MAX_READY_RETRIES, 1);
	if (!SRpnt)
		return (STp->buffer)->syscall_result;

	if ((STp->buffer)->syscall_result != 0 ||
	    (STp->device->scsi_level >= SCSI_2 &&
	     ((STp->buffer)->b_data[0] & 4) != 0)) {
		*block = *partition = 0;
                DEBC(printk(ST_DEB_MSG "%s: Can't read tape position.\n", name));
		result = (-EIO);
	} else {
		result = 0;
		if ((STp->device)->scsi_level < SCSI_2) {
			*block = ((STp->buffer)->b_data[0] << 16)
			    + ((STp->buffer)->b_data[1] << 8)
			    + (STp->buffer)->b_data[2];
			*partition = 0;
		} else {
			*block = ((STp->buffer)->b_data[4] << 24)
			    + ((STp->buffer)->b_data[5] << 16)
			    + ((STp->buffer)->b_data[6] << 8)
			    + (STp->buffer)->b_data[7];
			*partition = (STp->buffer)->b_data[1];
			if (((STp->buffer)->b_data[0] & 0x80) &&
			    (STp->buffer)->b_data[1] == 0)	/* BOP of partition 0 */
				STp->ps[0].drv_block = STp->ps[0].drv_file = 0;
		}
                DEBC(printk(ST_DEB_MSG "%s: Got tape pos. blk %d part %d.\n", name,
                            *block, *partition));
	}
	st_release_request(SRpnt);
	SRpnt = NULL;

	return result;
}


/* Set the tape block and partition. Negative partition means that only the
   block should be set in vendor specific way. */
static int set_location(struct scsi_tape *STp, unsigned int block, int partition,
			int logical)
{
	struct st_partstat *STps;
	int result, p;
	unsigned int blk;
	int timeout;
	unsigned char scmd[MAX_COMMAND_SIZE];
	struct st_request *SRpnt;
	DEB( char *name = tape_name(STp); )

	if (STp->ready != ST_READY)
		return (-EIO);
	timeout = STp->long_timeout;
	STps = &(STp->ps[STp->partition]);

        DEBC(printk(ST_DEB_MSG "%s: Setting block to %d and partition to %d.\n",
                    name, block, partition));
	DEB(if (partition < 0)
		return (-EIO); )

	/* Update the location at the partition we are leaving */
	if ((!STp->can_partitions && partition != 0) ||
	    partition >= ST_NBR_PARTITIONS)
		return (-EINVAL);
	if (partition != STp->partition) {
		if (get_location(STp, &blk, &p, 1))
			STps->last_block_valid = 0;
		else {
			STps->last_block_valid = 1;
			STps->last_block_visited = blk;
                        DEBC(printk(ST_DEB_MSG
                                    "%s: Visited block %d for partition %d saved.\n",
                                    name, blk, STp->partition));
		}
	}

	memset(scmd, 0, MAX_COMMAND_SIZE);
	if ((STp->device)->scsi_level < SCSI_2) {
		scmd[0] = QFA_SEEK_BLOCK;
		scmd[2] = (block >> 16);
		scmd[3] = (block >> 8);
		scmd[4] = block;
		scmd[5] = 0;
	} else {
		scmd[0] = SEEK_10;
		scmd[3] = (block >> 24);
		scmd[4] = (block >> 16);
		scmd[5] = (block >> 8);
		scmd[6] = block;
		if (!logical && !STp->scsi2_logical)
			scmd[1] = 4;
		if (STp->partition != partition) {
			scmd[1] |= 2;
			scmd[8] = partition;
                        DEBC(printk(ST_DEB_MSG
                                    "%s: Trying to change partition from %d to %d\n",
                                    name, STp->partition, partition));
		}
	}
	if (STp->immediate) {
		scmd[1] |= 1;		/* Don't wait for completion */
		timeout = STp->device->request_queue->rq_timeout;
	}

	SRpnt = st_do_scsi(NULL, STp, scmd, 0, DMA_NONE,
			   timeout, MAX_READY_RETRIES, 1);
	if (!SRpnt)
		return (STp->buffer)->syscall_result;

	STps->drv_block = STps->drv_file = (-1);
	STps->eof = ST_NOEOF;
	if ((STp->buffer)->syscall_result != 0) {
		result = (-EIO);
		if (STp->can_partitions &&
		    (STp->device)->scsi_level >= SCSI_2 &&
		    (p = find_partition(STp)) >= 0)
			STp->partition = p;
	} else {
		if (STp->can_partitions) {
			STp->partition = partition;
			STps = &(STp->ps[partition]);
			if (!STps->last_block_valid ||
			    STps->last_block_visited != block) {
				STps->at_sm = 0;
				STps->rw = ST_IDLE;
			}
		} else
			STps->at_sm = 0;
		if (block == 0)
			STps->drv_block = STps->drv_file = 0;
		result = 0;
	}

	st_release_request(SRpnt);
	SRpnt = NULL;

	return result;
}


/* Find the current partition number for the drive status. Called from open and
   returns either partition number of negative error code. */
static int find_partition(struct scsi_tape *STp)
{
	int i, partition;
	unsigned int block;

	if ((i = get_location(STp, &block, &partition, 1)) < 0)
		return i;
	if (partition >= ST_NBR_PARTITIONS)
		return (-EIO);
	return partition;
}


/* Change the partition if necessary */
static int switch_partition(struct scsi_tape *STp)
{
	struct st_partstat *STps;

	if (STp->partition == STp->new_partition)
		return 0;
	STps = &(STp->ps[STp->new_partition]);
	if (!STps->last_block_valid)
		STps->last_block_visited = 0;
	return set_location(STp, STps->last_block_visited, STp->new_partition, 1);
}

/* Functions for reading and writing the medium partition mode page. */

#define PART_PAGE   0x11
#define PART_PAGE_FIXED_LENGTH 8

#define PP_OFF_MAX_ADD_PARTS   2
#define PP_OFF_NBR_ADD_PARTS   3
#define PP_OFF_FLAGS           4
#define PP_OFF_PART_UNITS      6
#define PP_OFF_RESERVED        7

#define PP_BIT_IDP             0x20
#define PP_MSK_PSUM_MB         0x10

/* Get the number of partitions on the tape. As a side effect reads the
   mode page into the tape buffer. */
static int nbr_partitions(struct scsi_tape *STp)
{
	int result;
	DEB( char *name = tape_name(STp); )

	if (STp->ready != ST_READY)
		return (-EIO);

	result = read_mode_page(STp, PART_PAGE, 1);

	if (result) {
                DEBC(printk(ST_DEB_MSG "%s: Can't read medium partition page.\n",
                            name));
		result = (-EIO);
	} else {
		result = (STp->buffer)->b_data[MODE_HEADER_LENGTH +
					      PP_OFF_NBR_ADD_PARTS] + 1;
                DEBC(printk(ST_DEB_MSG "%s: Number of partitions %d.\n", name, result));
	}

	return result;
}


/* Partition the tape into two partitions if size > 0 or one partition if
   size == 0.

   The block descriptors are read and written because Sony SDT-7000 does not
   work without this (suggestion from Michael Schaefer <Michael.Schaefer@dlr.de>).

   My HP C1533A drive returns only one partition size field. This is used to
   set the size of partition 1. There is no size field for the default partition.
   Michael Schaefer's Sony SDT-7000 returns two descriptors and the second is
   used to set the size of partition 1 (this is what the SCSI-3 standard specifies).
   The following algorithm is used to accommodate both drives: if the number of
   partition size fields is greater than the maximum number of additional partitions
   in the mode page, the second field is used. Otherwise the first field is used.

   For Seagate DDS drives the page length must be 8 when no partitions is defined
   and 10 when 1 partition is defined (information from Eric Lee Green). This is
   is acceptable also to some other old drives and enforced if the first partition
   size field is used for the first additional partition size.
 */
static int partition_tape(struct scsi_tape *STp, int size)
{
	char *name = tape_name(STp);
	int result;
	int pgo, psd_cnt, psdo;
	unsigned char *bp;

	result = read_mode_page(STp, PART_PAGE, 0);
	if (result) {
		DEBC(printk(ST_DEB_MSG "%s: Can't read partition mode page.\n", name));
		return result;
	}
	/* The mode page is in the buffer. Let's modify it and write it. */
	bp = (STp->buffer)->b_data;
	pgo = MODE_HEADER_LENGTH + bp[MH_OFF_BDESCS_LENGTH];
	DEBC(printk(ST_DEB_MSG "%s: Partition page length is %d bytes.\n",
		    name, bp[pgo + MP_OFF_PAGE_LENGTH] + 2));

	psd_cnt = (bp[pgo + MP_OFF_PAGE_LENGTH] + 2 - PART_PAGE_FIXED_LENGTH) / 2;
	psdo = pgo + PART_PAGE_FIXED_LENGTH;
	if (psd_cnt > bp[pgo + PP_OFF_MAX_ADD_PARTS]) {
		bp[psdo] = bp[psdo + 1] = 0xff;  /* Rest of the tape */
		psdo += 2;
	}
	memset(bp + psdo, 0, bp[pgo + PP_OFF_NBR_ADD_PARTS] * 2);

	DEBC(printk("%s: psd_cnt %d, max.parts %d, nbr_parts %d\n", name,
		    psd_cnt, bp[pgo + PP_OFF_MAX_ADD_PARTS],
		    bp[pgo + PP_OFF_NBR_ADD_PARTS]));

	if (size <= 0) {
		bp[pgo + PP_OFF_NBR_ADD_PARTS] = 0;
		if (psd_cnt <= bp[pgo + PP_OFF_MAX_ADD_PARTS])
		    bp[pgo + MP_OFF_PAGE_LENGTH] = 6;
                DEBC(printk(ST_DEB_MSG "%s: Formatting tape with one partition.\n",
                            name));
	} else {
		bp[psdo] = (size >> 8) & 0xff;
		bp[psdo + 1] = size & 0xff;
		bp[pgo + 3] = 1;
		if (bp[pgo + MP_OFF_PAGE_LENGTH] < 8)
		    bp[pgo + MP_OFF_PAGE_LENGTH] = 8;
                DEBC(printk(ST_DEB_MSG
                            "%s: Formatting tape with two partitions (1 = %d MB).\n",
                            name, size));
	}
	bp[pgo + PP_OFF_PART_UNITS] = 0;
	bp[pgo + PP_OFF_RESERVED] = 0;
	bp[pgo + PP_OFF_FLAGS] = PP_BIT_IDP | PP_MSK_PSUM_MB;

	result = write_mode_page(STp, PART_PAGE, 1);
	if (result) {
		printk(KERN_INFO "%s: Partitioning of tape failed.\n", name);
		result = (-EIO);
	}

	return result;
}



/* The ioctl command */
static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
{
	int i, cmd_nr, cmd_type, bt;
	int retval = 0;
	unsigned int blk;
	struct scsi_tape *STp = file->private_data;
	struct st_modedef *STm;
	struct st_partstat *STps;
	char *name = tape_name(STp);
	void __user *p = (void __user *)arg;

	if (mutex_lock_interruptible(&STp->lock))
		return -ERESTARTSYS;

        DEB(
	if (debugging && !STp->in_use) {
		printk(ST_DEB_MSG "%s: Incorrect device.\n", name);
		retval = (-EIO);
		goto out;
	} ) /* end DEB */

	STm = &(STp->modes[STp->current_mode]);
	STps = &(STp->ps[STp->partition]);

	/*
	 * If we are in the middle of error recovery, don't let anyone
	 * else try and use this device.  Also, if error recovery fails, it
	 * may try and take the device offline, in which case all further
	 * access to the device is prohibited.
	 */
	retval = scsi_nonblockable_ioctl(STp->device, cmd_in, p,
					file->f_flags & O_NDELAY);
	if (!scsi_block_when_processing_errors(STp->device) || retval != -ENODEV)
		goto out;
	retval = 0;

	cmd_type = _IOC_TYPE(cmd_in);
	cmd_nr = _IOC_NR(cmd_in);

	if (cmd_type == _IOC_TYPE(MTIOCTOP) && cmd_nr == _IOC_NR(MTIOCTOP)) {
		struct mtop mtc;

		if (_IOC_SIZE(cmd_in) != sizeof(mtc)) {
			retval = (-EINVAL);
			goto out;
		}

		i = copy_from_user(&mtc, p, sizeof(struct mtop));
		if (i) {
			retval = (-EFAULT);
			goto out;
		}

		if (mtc.mt_op == MTSETDRVBUFFER && !capable(CAP_SYS_ADMIN)) {
			printk(KERN_WARNING
                               "%s: MTSETDRVBUFFER only allowed for root.\n", name);
			retval = (-EPERM);
			goto out;
		}
		if (!STm->defined &&
		    (mtc.mt_op != MTSETDRVBUFFER &&
		     (mtc.mt_count & MT_ST_OPTIONS) == 0)) {
			retval = (-ENXIO);
			goto out;
		}

		if (!STp->pos_unknown) {

			if (STps->eof == ST_FM_HIT) {
				if (mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
                                    mtc.mt_op == MTEOM) {
					mtc.mt_count -= 1;
					if (STps->drv_file >= 0)
						STps->drv_file += 1;
				} else if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM) {
					mtc.mt_count += 1;
					if (STps->drv_file >= 0)
						STps->drv_file += 1;
				}
			}

			if (mtc.mt_op == MTSEEK) {
				/* Old position must be restored if partition will be
                                   changed */
				i = !STp->can_partitions ||
				    (STp->new_partition != STp->partition);
			} else {
				i = mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
				    mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM ||
				    mtc.mt_op == MTLOCK || mtc.mt_op == MTLOAD ||
				    mtc.mt_op == MTFSF || mtc.mt_op == MTFSFM ||
				    mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM ||
				    mtc.mt_op == MTCOMPRESSION;
			}
			i = flush_buffer(STp, i);
			if (i < 0) {
				retval = i;
				goto out;
			}
			if (STps->rw == ST_WRITING &&
			    (mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
			     mtc.mt_op == MTSEEK ||
			     mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)) {
				i = st_int_ioctl(STp, MTWEOF, 1);
				if (i < 0) {
					retval = i;
					goto out;
				}
				if (mtc.mt_op == MTBSF || mtc.mt_op == MTBSFM)
					mtc.mt_count++;
				STps->rw = ST_IDLE;
			     }

		} else {
			/*
			 * If there was a bus reset, block further access
			 * to this device.  If the user wants to rewind the tape,
			 * then reset the flag and allow access again.
			 */
			if (mtc.mt_op != MTREW &&
			    mtc.mt_op != MTOFFL &&
			    mtc.mt_op != MTRETEN &&
			    mtc.mt_op != MTERASE &&
			    mtc.mt_op != MTSEEK &&
			    mtc.mt_op != MTEOM) {
				retval = (-EIO);
				goto out;
			}
			reset_state(STp);
			/* remove this when the midlevel properly clears was_reset */
			STp->device->was_reset = 0;
		}

		if (mtc.mt_op != MTNOP && mtc.mt_op != MTSETBLK &&
		    mtc.mt_op != MTSETDENSITY && mtc.mt_op != MTWSM &&
		    mtc.mt_op != MTSETDRVBUFFER && mtc.mt_op != MTSETPART)
			STps->rw = ST_IDLE;	/* Prevent automatic WEOF and fsf */

		if (mtc.mt_op == MTOFFL && STp->door_locked != ST_UNLOCKED)
			do_door_lock(STp, 0);	/* Ignore result! */

		if (mtc.mt_op == MTSETDRVBUFFER &&
		    (mtc.mt_count & MT_ST_OPTIONS) != 0) {
			retval = st_set_options(STp, mtc.mt_count);
			goto out;
		}

		if (mtc.mt_op == MTSETPART) {
			if (!STp->can_partitions ||
			    mtc.mt_count < 0 || mtc.mt_count >= ST_NBR_PARTITIONS) {
				retval = (-EINVAL);
				goto out;
			}
			if (mtc.mt_count >= STp->nbr_partitions &&
			    (STp->nbr_partitions = nbr_partitions(STp)) < 0) {
				retval = (-EIO);
				goto out;
			}
			if (mtc.mt_count >= STp->nbr_partitions) {
				retval = (-EINVAL);
				goto out;
			}
			STp->new_partition = mtc.mt_count;
			retval = 0;
			goto out;
		}

		if (mtc.mt_op == MTMKPART) {
			if (!STp->can_partitions) {
				retval = (-EINVAL);
				goto out;
			}
			if ((i = st_int_ioctl(STp, MTREW, 0)) < 0 ||
			    (i = partition_tape(STp, mtc.mt_count)) < 0) {
				retval = i;
				goto out;
			}
			for (i = 0; i < ST_NBR_PARTITIONS; i++) {
				STp->ps[i].rw = ST_IDLE;
				STp->ps[i].at_sm = 0;
				STp->ps[i].last_block_valid = 0;
			}
			STp->partition = STp->new_partition = 0;
			STp->nbr_partitions = 1;	/* Bad guess ?-) */
			STps->drv_block = STps->drv_file = 0;
			retval = 0;
			goto out;
		}

		if (mtc.mt_op == MTSEEK) {
			i = set_location(STp, mtc.mt_count, STp->new_partition, 0);
			if (!STp->can_partitions)
				STp->ps[0].rw = ST_IDLE;
			retval = i;
			goto out;
		}

		if (mtc.mt_op == MTUNLOAD || mtc.mt_op == MTOFFL) {
			retval = do_load_unload(STp, file, 0);
			goto out;
		}

		if (mtc.mt_op == MTLOAD) {
			retval = do_load_unload(STp, file, max(1, mtc.mt_count));
			goto out;
		}

		if (mtc.mt_op == MTLOCK || mtc.mt_op == MTUNLOCK) {
			retval = do_door_lock(STp, (mtc.mt_op == MTLOCK));
			goto out;
		}

		if (STp->can_partitions && STp->ready == ST_READY &&
		    (i = switch_partition(STp)) < 0) {
			retval = i;
			goto out;
		}

		if (mtc.mt_op == MTCOMPRESSION)
			retval = st_compression(STp, (mtc.mt_count & 1));
		else
			retval = st_int_ioctl(STp, mtc.mt_op, mtc.mt_count);
		goto out;
	}
	if (!STm->defined) {
		retval = (-ENXIO);
		goto out;
	}

	if ((i = flush_buffer(STp, 0)) < 0) {
		retval = i;
		goto out;
	}
	if (STp->can_partitions &&
	    (i = switch_partition(STp)) < 0) {
		retval = i;
		goto out;
	}

	if (cmd_type == _IOC_TYPE(MTIOCGET) && cmd_nr == _IOC_NR(MTIOCGET)) {
		struct mtget mt_status;

		if (_IOC_SIZE(cmd_in) != sizeof(struct mtget)) {
			 retval = (-EINVAL);
			 goto out;
		}

		mt_status.mt_type = STp->tape_type;
		mt_status.mt_dsreg =
		    ((STp->block_size << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK) |
		    ((STp->density << MT_ST_DENSITY_SHIFT) & MT_ST_DENSITY_MASK);
		mt_status.mt_blkno = STps->drv_block;
		mt_status.mt_fileno = STps->drv_file;
		if (STp->block_size != 0) {
			if (STps->rw == ST_WRITING)
				mt_status.mt_blkno +=
				    (STp->buffer)->buffer_bytes / STp->block_size;
			else if (STps->rw == ST_READING)
				mt_status.mt_blkno -=
                                        ((STp->buffer)->buffer_bytes +
                                         STp->block_size - 1) / STp->block_size;
		}

		mt_status.mt_gstat = 0;
		if (STp->drv_write_prot)
			mt_status.mt_gstat |= GMT_WR_PROT(0xffffffff);
		if (mt_status.mt_blkno == 0) {
			if (mt_status.mt_fileno == 0)
				mt_status.mt_gstat |= GMT_BOT(0xffffffff);
			else
				mt_status.mt_gstat |= GMT_EOF(0xffffffff);
		}
		mt_status.mt_erreg = (STp->recover_reg << MT_ST_SOFTERR_SHIFT);
		mt_status.mt_resid = STp->partition;
		if (STps->eof == ST_EOM_OK || STps->eof == ST_EOM_ERROR)
			mt_status.mt_gstat |= GMT_EOT(0xffffffff);
		else if (STps->eof >= ST_EOM_OK)
			mt_status.mt_gstat |= GMT_EOD(0xffffffff);
		if (STp->density == 1)
			mt_status.mt_gstat |= GMT_D_800(0xffffffff);
		else if (STp->density == 2)
			mt_status.mt_gstat |= GMT_D_1600(0xffffffff);
		else if (STp->density == 3)
			mt_status.mt_gstat |= GMT_D_6250(0xffffffff);
		if (STp->ready == ST_READY)
			mt_status.mt_gstat |= GMT_ONLINE(0xffffffff);
		if (STp->ready == ST_NO_TAPE)
			mt_status.mt_gstat |= GMT_DR_OPEN(0xffffffff);
		if (STps->at_sm)
			mt_status.mt_gstat |= GMT_SM(0xffffffff);
		if (STm->do_async_writes ||
                    (STm->do_buffer_writes && STp->block_size != 0) ||
		    STp->drv_buffer != 0)
			mt_status.mt_gstat |= GMT_IM_REP_EN(0xffffffff);
		if (STp->cleaning_req)
			mt_status.mt_gstat |= GMT_CLN(0xffffffff);

		i = copy_to_user(p, &mt_status, sizeof(struct mtget));
		if (i) {
			retval = (-EFAULT);
			goto out;
		}

		STp->recover_reg = 0;		/* Clear after read */
		retval = 0;
		goto out;
	}			/* End of MTIOCGET */
	if (cmd_type == _IOC_TYPE(MTIOCPOS) && cmd_nr == _IOC_NR(MTIOCPOS)) {
		struct mtpos mt_pos;
		if (_IOC_SIZE(cmd_in) != sizeof(struct mtpos)) {
			 retval = (-EINVAL);
			 goto out;
		}
		if ((i = get_location(STp, &blk, &bt, 0)) < 0) {
			retval = i;
			goto out;
		}
		mt_pos.mt_blkno = blk;
		i = copy_to_user(p, &mt_pos, sizeof(struct mtpos));
		if (i)
			retval = (-EFAULT);
		goto out;
	}
	mutex_unlock(&STp->lock);
	switch (cmd_in) {
		case SCSI_IOCTL_GET_IDLUN:
		case SCSI_IOCTL_GET_BUS_NUMBER:
			break;
		default:
			if ((cmd_in == SG_IO ||
			     cmd_in == SCSI_IOCTL_SEND_COMMAND ||
			     cmd_in == CDROM_SEND_PACKET) &&
			    !capable(CAP_SYS_RAWIO))
				i = -EPERM;
			else
				i = scsi_cmd_ioctl(STp->disk->queue, STp->disk,
						   file->f_mode, cmd_in, p);
			if (i != -ENOTTY)
				return i;
			break;
	}
	retval = scsi_ioctl(STp->device, cmd_in, p);
	if (!retval && cmd_in == SCSI_IOCTL_STOP_UNIT) { /* unload */
		STp->rew_at_close = 0;
		STp->ready = ST_NO_TAPE;
	}
	return retval;

 out:
	mutex_unlock(&STp->lock);
	return retval;
}

#ifdef CONFIG_COMPAT
static long st_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct scsi_tape *STp = file->private_data;
	struct scsi_device *sdev = STp->device;
	int ret = -ENOIOCTLCMD;
	if (sdev->host->hostt->compat_ioctl) { 

		ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);

	}
	return ret;
}
#endif



/* Try to allocate a new tape buffer. Calling function must not hold
   dev_arr_lock. */
static struct st_buffer *new_tape_buffer(int need_dma, int max_sg)
{
	struct st_buffer *tb;

	tb = kzalloc(sizeof(struct st_buffer), GFP_ATOMIC);
	if (!tb) {
		printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
		return NULL;
	}
	tb->frp_segs = 0;
	tb->use_sg = max_sg;
	tb->dma = need_dma;
	tb->buffer_size = 0;

	tb->reserved_pages = kzalloc(max_sg * sizeof(struct page *),
				     GFP_ATOMIC);
	if (!tb->reserved_pages) {
		kfree(tb);
		return NULL;
	}

	return tb;
}


/* Try to allocate enough space in the tape buffer */
#define ST_MAX_ORDER 6

static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dma)
{
	int segs, nbr, max_segs, b_size, order, got;
	gfp_t priority;

	if (new_size <= STbuffer->buffer_size)
		return 1;

	if (STbuffer->buffer_size <= PAGE_SIZE)
		normalize_buffer(STbuffer);  /* Avoid extra segment */

	max_segs = STbuffer->use_sg;
	nbr = max_segs - STbuffer->frp_segs;
	if (nbr <= 0)
		return 0;

	priority = GFP_KERNEL | __GFP_NOWARN;
	if (need_dma)
		priority |= GFP_DMA;

	if (STbuffer->cleared)
		priority |= __GFP_ZERO;

	if (STbuffer->frp_segs) {
		order = STbuffer->reserved_page_order;
		b_size = PAGE_SIZE << order;
	} else {
		for (b_size = PAGE_SIZE, order = 0;
		     order < ST_MAX_ORDER &&
			     max_segs * (PAGE_SIZE << order) < new_size;
		     order++, b_size *= 2)
			;  /* empty */
		STbuffer->reserved_page_order = order;
	}
	if (max_segs * (PAGE_SIZE << order) < new_size) {
		if (order == ST_MAX_ORDER)
			return 0;
		normalize_buffer(STbuffer);
		return enlarge_buffer(STbuffer, new_size, need_dma);
	}

	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
	     segs < max_segs && got < new_size;) {
		struct page *page;

		page = alloc_pages(priority, order);
		if (!page) {
			DEB(STbuffer->buffer_size = got);
			normalize_buffer(STbuffer);
			return 0;
		}

		STbuffer->frp_segs += 1;
		got += b_size;
		STbuffer->buffer_size = got;
		STbuffer->reserved_pages[segs] = page;
		segs++;
	}
	STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);

	return 1;
}


/* Make sure that no data from previous user is in the internal buffer */
static void clear_buffer(struct st_buffer * st_bp)
{
	int i;

	for (i=0; i < st_bp->frp_segs; i++)
		memset(page_address(st_bp->reserved_pages[i]), 0,
		       PAGE_SIZE << st_bp->reserved_page_order);
	st_bp->cleared = 1;
}


/* Release the extra buffer */
static void normalize_buffer(struct st_buffer * STbuffer)
{
	int i, order = STbuffer->reserved_page_order;

	for (i = 0; i < STbuffer->frp_segs; i++) {
		__free_pages(STbuffer->reserved_pages[i], order);
		STbuffer->buffer_size -= (PAGE_SIZE << order);
	}
	STbuffer->frp_segs = 0;
	STbuffer->sg_segs = 0;
	STbuffer->reserved_page_order = 0;
	STbuffer->map_data.offset = 0;
}


/* Move data from the user buffer to the tape buffer. Returns zero (success) or
   negative error code. */
static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
{
	int i, cnt, res, offset;
	int length = PAGE_SIZE << st_bp->reserved_page_order;

	for (i = 0, offset = st_bp->buffer_bytes;
	     i < st_bp->frp_segs && offset >= length; i++)
		offset -= length;
	if (i == st_bp->frp_segs) {	/* Should never happen */
		printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
		return (-EIO);
	}
	for (; i < st_bp->frp_segs && do_count > 0; i++) {
		struct page *page = st_bp->reserved_pages[i];
		cnt = length - offset < do_count ? length - offset : do_count;
		res = copy_from_user(page_address(page) + offset, ubp, cnt);
		if (res)
			return (-EFAULT