aboutsummaryrefslogblamecommitdiffstats
path: root/fs/jfs/jfs_xtree.c
blob: 2c1f311914a101d9ee631327f0421956a8caa1a5 (plain) (tree)
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
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
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
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
















































































































                                                                                                         

                                                                     













































                                                                           
                                   


                  

                     















                                                                             
                                                                    
















                                                                   


                                                         
                         
         



















































































                                                                        
                                                                 










































































































































































































                                                                      
                                                                 








                                                                           
                                                           












                                                                  
                     



































































                                                                            
                                                           











































                                                                                   


                                              



















































                                                                                


                                                                

                                                                             














                                                                        

                                                        
































                                                                       


                                              

































































                                                                               
                 












                                                                         
                                                                        






                                                                       
                                                           










































































































































































































































































































































































































































































































































































































































































































































































































































                                                                               
                                                                           






































































































































































                                                                               
                                                                       





















































































































































































                                                                               
                                                                        
























































































































































































































































































































                                                                                   
                                                                                

















































































































































                                                                               
                 













                                                                         
                                                                        








                                                        


                                                     









































































































































                                                                                        
                                                               


























































































































































































































































                                                                               
                                                                 








































































































                                                                               
                                                                       







































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                
                                                                 










































































































































































































































































































































































































































































































                                                                                   
/*
 *   Copyright (C) International Business Machines Corp., 2000-2004
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or 
 *   (at your option) any later version.
 * 
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software 
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
/*
 *      jfs_xtree.c: extent allocation descriptor B+-tree manager
 */

#include <linux/fs.h>
#include <linux/quotaops.h>
#include "jfs_incore.h"
#include "jfs_filsys.h"
#include "jfs_metapage.h"
#include "jfs_dmap.h"
#include "jfs_dinode.h"
#include "jfs_superblock.h"
#include "jfs_debug.h"

/*
 * xtree local flag
 */
#define XT_INSERT       0x00000001

/*
 *       xtree key/entry comparison: extent offset
 *
 * return:
 *      -1: k < start of extent
 *       0: start_of_extent <= k <= end_of_extent
 *       1: k > end_of_extent
 */
#define XT_CMP(CMP, K, X, OFFSET64)\
{\
        OFFSET64 = offsetXAD(X);\
        (CMP) = ((K) >= OFFSET64 + lengthXAD(X)) ? 1 :\
              ((K) < OFFSET64) ? -1 : 0;\
}

/* write a xad entry */
#define XT_PUTENTRY(XAD, FLAG, OFF, LEN, ADDR)\
{\
        (XAD)->flag = (FLAG);\
        XADoffset((XAD), (OFF));\
        XADlength((XAD), (LEN));\
        XADaddress((XAD), (ADDR));\
}

#define XT_PAGE(IP, MP) BT_PAGE(IP, MP, xtpage_t, i_xtroot)

/* get page buffer for specified block address */
/* ToDo: Replace this ugly macro with a function */
#define XT_GETPAGE(IP, BN, MP, SIZE, P, RC)\
{\
	BT_GETPAGE(IP, BN, MP, xtpage_t, SIZE, P, RC, i_xtroot)\
	if (!(RC))\
	{\
		if ((le16_to_cpu((P)->header.nextindex) < XTENTRYSTART) ||\
		    (le16_to_cpu((P)->header.nextindex) > le16_to_cpu((P)->header.maxentry)) ||\
		    (le16_to_cpu((P)->header.maxentry) > (((BN)==0)?XTROOTMAXSLOT:PSIZE>>L2XTSLOTSIZE)))\
		{\
			jfs_error((IP)->i_sb, "XT_GETPAGE: xtree page corrupt");\
			BT_PUTPAGE(MP);\
			MP = NULL;\
			RC = -EIO;\
		}\
        }\
}

/* for consistency */
#define XT_PUTPAGE(MP) BT_PUTPAGE(MP)

#define XT_GETSEARCH(IP, LEAF, BN, MP,  P, INDEX) \
	BT_GETSEARCH(IP, LEAF, BN, MP, xtpage_t, P, INDEX, i_xtroot)
/* xtree entry parameter descriptor */
struct xtsplit {
	struct metapage *mp;
	s16 index;
	u8 flag;
	s64 off;
	s64 addr;
	int len;
	struct pxdlist *pxdlist;
};


/*
 *      statistics
 */
#ifdef CONFIG_JFS_STATISTICS
static struct {
	uint search;
	uint fastSearch;
	uint split;
} xtStat;
#endif


/*
 * forward references
 */
static int xtSearch(struct inode *ip, s64 xoff, s64 *next, int *cmpp,
		    struct btstack * btstack, int flag);

static int xtSplitUp(tid_t tid,
		     struct inode *ip,
		     struct xtsplit * split, struct btstack * btstack);

static int xtSplitPage(tid_t tid, struct inode *ip, struct xtsplit * split,
		       struct metapage ** rmpp, s64 * rbnp);

static int xtSplitRoot(tid_t tid, struct inode *ip,
		       struct xtsplit * split, struct metapage ** rmpp);

#ifdef _STILL_TO_PORT
static int xtDeleteUp(tid_t tid, struct inode *ip, struct metapage * fmp,
		      xtpage_t * fp, struct btstack * btstack);

static int xtSearchNode(struct inode *ip,
			xad_t * xad,
			int *cmpp, struct btstack * btstack, int flag);

static int xtRelink(tid_t tid, struct inode *ip, xtpage_t * fp);
#endif				/*  _STILL_TO_PORT */

/* External references */

/*
 *      debug control
 */
/*      #define _JFS_DEBUG_XTREE        1 */


/*
 *      xtLookup()
 *
 * function: map a single page into a physical extent;
 */
int xtLookup(struct inode *ip, s64 lstart,
	     s64 llen, int *pflag, s64 * paddr, s32 * plen, int no_check)
{
	int rc = 0;
	struct btstack btstack;
	int cmp;
	s64 bn;
	struct metapage *mp;
	xtpage_t *p;
	int index;
	xad_t *xad;
	s64 next, size, xoff, xend;
	int xlen;
	s64 xaddr;

	*paddr = 0;
	*plen = llen;

	if (!no_check) {
		/* is lookup offset beyond eof ? */
		size = ((u64) ip->i_size + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
		    JFS_SBI(ip->i_sb)->l2bsize;
		if (lstart >= size) {
			jfs_err("xtLookup: lstart (0x%lx) >= size (0x%lx)",
				(ulong) lstart, (ulong) size);
			return 0;
		}
	}

	/*
	 * search for the xad entry covering the logical extent
	 */
//search:
	if ((rc = xtSearch(ip, lstart, &next, &cmp, &btstack, 0))) {
		jfs_err("xtLookup: xtSearch returned %d", rc);
		return rc;
	}

	/*
	 *      compute the physical extent covering logical extent
	 *
	 * N.B. search may have failed (e.g., hole in sparse file),
	 * and returned the index of the next entry.
	 */
	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

	/* is xad found covering start of logical extent ?
	 * lstart is a page start address,
	 * i.e., lstart cannot start in a hole;
	 */
	if (cmp) {
		if (next)
			*plen = min(next - lstart, llen);
		goto out;
	}

	/*
	 * lxd covered by xad
	 */
	xad = &p->xad[index];
	xoff = offsetXAD(xad);
	xlen = lengthXAD(xad);
	xend = xoff + xlen;
	xaddr = addressXAD(xad);

	/* initialize new pxd */
	*pflag = xad->flag;
	*paddr = xaddr + (lstart - xoff);
	/* a page must be fully covered by an xad */
	*plen = min(xend - lstart, llen);

      out:
	XT_PUTPAGE(mp);

	return rc;
}


/*
 *      xtLookupList()
 *
 * function: map a single logical extent into a list of physical extent;
 *
 * parameter:
 *      struct inode    *ip,
 *      struct lxdlist  *lxdlist,       lxd list (in)
 *      struct xadlist  *xadlist,       xad list (in/out)
 *      int		flag)
 *
 * coverage of lxd by xad under assumption of
 * . lxd's are ordered and disjoint.
 * . xad's are ordered and disjoint.
 *
 * return:
 *      0:      success
 *
 * note: a page being written (even a single byte) is backed fully,
 *      except the last page which is only backed with blocks
 *      required to cover the last byte;
 *      the extent backing a page is fully contained within an xad;
 */
int xtLookupList(struct inode *ip, struct lxdlist * lxdlist,
		 struct xadlist * xadlist, int flag)
{
	int rc = 0;
	struct btstack btstack;
	int cmp;
	s64 bn;
	struct metapage *mp;
	xtpage_t *p;
	int index;
	lxd_t *lxd;
	xad_t *xad, *pxd;
	s64 size, lstart, lend, xstart, xend, pstart;
	s64 llen, xlen, plen;
	s64 xaddr, paddr;
	int nlxd, npxd, maxnpxd;

	npxd = xadlist->nxad = 0;
	maxnpxd = xadlist->maxnxad;
	pxd = xadlist->xad;

	nlxd = lxdlist->nlxd;
	lxd = lxdlist->lxd;

	lstart = offsetLXD(lxd);
	llen = lengthLXD(lxd);
	lend = lstart + llen;

	size = (ip->i_size + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
	    JFS_SBI(ip->i_sb)->l2bsize;

	/*
	 * search for the xad entry covering the logical extent
	 */
      search:
	if (lstart >= size)
		return 0;

	if ((rc = xtSearch(ip, lstart, NULL, &cmp, &btstack, 0)))
		return rc;

	/*
	 *      compute the physical extent covering logical extent
	 *
	 * N.B. search may have failed (e.g., hole in sparse file),
	 * and returned the index of the next entry.
	 */
//map:
	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

	/* is xad on the next sibling page ? */
	if (index == le16_to_cpu(p->header.nextindex)) {
		if (p->header.flag & BT_ROOT)
			goto mapend;

		if ((bn = le64_to_cpu(p->header.next)) == 0)
			goto mapend;

		XT_PUTPAGE(mp);

		/* get next sibling page */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		index = XTENTRYSTART;
	}

	xad = &p->xad[index];

	/*
	 * is lxd covered by xad ?
	 */
      compare:
	xstart = offsetXAD(xad);
	xlen = lengthXAD(xad);
	xend = xstart + xlen;
	xaddr = addressXAD(xad);

      compare1:
	if (xstart < lstart)
		goto compare2;

	/* (lstart <= xstart) */

	/* lxd is NOT covered by xad */
	if (lend <= xstart) {
		/*
		 * get next lxd
		 */
		if (--nlxd == 0)
			goto mapend;
		lxd++;

		lstart = offsetLXD(lxd);
		llen = lengthLXD(lxd);
		lend = lstart + llen;
		if (lstart >= size)
			goto mapend;

		/* compare with the current xad  */
		goto compare1;
	}
	/* lxd is covered by xad */
	else {			/* (xstart < lend) */

		/* initialize new pxd */
		pstart = xstart;
		plen = min(lend - xstart, xlen);
		paddr = xaddr;

		goto cover;
	}

	/* (xstart < lstart) */
      compare2:
	/* lxd is covered by xad */
	if (lstart < xend) {
		/* initialize new pxd */
		pstart = lstart;
		plen = min(xend - lstart, llen);
		paddr = xaddr + (lstart - xstart);

		goto cover;
	}
	/* lxd is NOT covered by xad */
	else {			/* (xend <= lstart) */

		/*
		 * get next xad
		 *
		 * linear search next xad covering lxd on
		 * the current xad page, and then tree search
		 */
		if (index == le16_to_cpu(p->header.nextindex) - 1) {
			if (p->header.flag & BT_ROOT)
				goto mapend;

			XT_PUTPAGE(mp);
			goto search;
		} else {
			index++;
			xad++;

			/* compare with new xad */
			goto compare;
		}
	}

	/*
	 * lxd is covered by xad and a new pxd has been initialized
	 * (lstart <= xstart < lend) or (xstart < lstart < xend)
	 */
      cover:
	/* finalize pxd corresponding to current xad */
	XT_PUTENTRY(pxd, xad->flag, pstart, plen, paddr);

	if (++npxd >= maxnpxd)
		goto mapend;
	pxd++;

	/*
	 * lxd is fully covered by xad
	 */
	if (lend <= xend) {
		/*
		 * get next lxd
		 */
		if (--nlxd == 0)
			goto mapend;
		lxd++;

		lstart = offsetLXD(lxd);
		llen = lengthLXD(lxd);
		lend = lstart + llen;
		if (lstart >= size)
			goto mapend;

		/*
		 * test for old xad covering new lxd
		 * (old xstart < new lstart)
		 */
		goto compare2;
	}
	/*
	 * lxd is partially covered by xad
	 */
	else {			/* (xend < lend)  */

		/*
		 * get next xad
		 *
		 * linear search next xad covering lxd on
		 * the current xad page, and then next xad page search
		 */
		if (index == le16_to_cpu(p->header.nextindex) - 1) {
			if (p->header.flag & BT_ROOT)
				goto mapend;

			if ((bn = le64_to_cpu(p->header.next)) == 0)
				goto mapend;

			XT_PUTPAGE(mp);

			/* get next sibling page */
			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
			if (rc)
				return rc;

			index = XTENTRYSTART;
			xad = &p->xad[index];
		} else {
			index++;
			xad++;
		}

		/*
		 * test for new xad covering old lxd
		 * (old lstart < new xstart)
		 */
		goto compare;
	}

      mapend:
	xadlist->nxad = npxd;

//out:
	XT_PUTPAGE(mp);

	return rc;
}


/*
 *      xtSearch()
 *
 * function:    search for the xad entry covering specified offset.
 *
 * parameters:
 *      ip      - file object;
 *      xoff    - extent offset;
 *      nextp	- address of next extent (if any) for search miss
 *      cmpp    - comparison result:
 *      btstack - traverse stack;
 *      flag    - search process flag (XT_INSERT);
 *
 * returns:
 *      btstack contains (bn, index) of search path traversed to the entry.
 *      *cmpp is set to result of comparison with the entry returned.
 *      the page containing the entry is pinned at exit.
 */
static int xtSearch(struct inode *ip, s64 xoff,	s64 *nextp,
		    int *cmpp, struct btstack * btstack, int flag)
{
	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
	int rc = 0;
	int cmp = 1;		/* init for empty page */
	s64 bn;			/* block number */
	struct metapage *mp;	/* page buffer */
	xtpage_t *p;		/* page */
	xad_t *xad;
	int base, index, lim, btindex;
	struct btframe *btsp;
	int nsplit = 0;		/* number of pages to split */
	s64 t64;
	s64 next = 0;

	INCREMENT(xtStat.search);

	BT_CLR(btstack);

	btstack->nsplit = 0;

	/*
	 *      search down tree from root:
	 *
	 * between two consecutive entries of <Ki, Pi> and <Kj, Pj> of
	 * internal page, child page Pi contains entry with k, Ki <= K < Kj.
	 *
	 * if entry with search key K is not found
	 * internal page search find the entry with largest key Ki
	 * less than K which point to the child page to search;
	 * leaf page search find the entry with smallest key Kj
	 * greater than K so that the returned index is the position of
	 * the entry to be shifted right for insertion of new entry.
	 * for empty tree, search key is greater than any key of the tree.
	 *
	 * by convention, root bn = 0.
	 */
	for (bn = 0;;) {
		/* get/pin the page to search */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		/* try sequential access heuristics with the previous
		 * access entry in target leaf page:
		 * once search narrowed down into the target leaf,
		 * key must either match an entry in the leaf or
		 * key entry does not exist in the tree;
		 */
//fastSearch:
		if ((jfs_ip->btorder & BT_SEQUENTIAL) &&
		    (p->header.flag & BT_LEAF) &&
		    (index = jfs_ip->btindex) <
		    le16_to_cpu(p->header.nextindex)) {
			xad = &p->xad[index];
			t64 = offsetXAD(xad);
			if (xoff < t64 + lengthXAD(xad)) {
				if (xoff >= t64) {
					*cmpp = 0;
					goto out;
				}

				/* stop sequential access heuristics */
				goto binarySearch;
			} else {	/* (t64 + lengthXAD(xad)) <= xoff */

				/* try next sequential entry */
				index++;
				if (index <
				    le16_to_cpu(p->header.nextindex)) {
					xad++;
					t64 = offsetXAD(xad);
					if (xoff < t64 + lengthXAD(xad)) {
						if (xoff >= t64) {
							*cmpp = 0;
							goto out;
						}

						/* miss: key falls between
						 * previous and this entry
						 */
						*cmpp = 1;
						next = t64;
						goto out;
					}

					/* (xoff >= t64 + lengthXAD(xad));
					 * matching entry may be further out:
					 * stop heuristic search
					 */
					/* stop sequential access heuristics */
					goto binarySearch;
				}

				/* (index == p->header.nextindex);
				 * miss: key entry does not exist in
				 * the target leaf/tree
				 */
				*cmpp = 1;
				goto out;
			}

			/*
			 * if hit, return index of the entry found, and
			 * if miss, where new entry with search key is
			 * to be inserted;
			 */
		      out:
			/* compute number of pages to split */
			if (flag & XT_INSERT) {
				if (p->header.nextindex ==	/* little-endian */
				    p->header.maxentry)
					nsplit++;
				else
					nsplit = 0;
				btstack->nsplit = nsplit;
			}

			/* save search result */
			btsp = btstack->top;
			btsp->bn = bn;
			btsp->index = index;
			btsp->mp = mp;

			/* update sequential access heuristics */
			jfs_ip->btindex = index;

			if (nextp)
				*nextp = next;

			INCREMENT(xtStat.fastSearch);
			return 0;
		}

		/* well, ... full search now */
	      binarySearch:
		lim = le16_to_cpu(p->header.nextindex) - XTENTRYSTART;

		/*
		 * binary search with search key K on the current page
		 */
		for (base = XTENTRYSTART; lim; lim >>= 1) {
			index = base + (lim >> 1);

			XT_CMP(cmp, xoff, &p->xad[index], t64);
			if (cmp == 0) {
				/*
				 *      search hit
				 */
				/* search hit - leaf page:
				 * return the entry found
				 */
				if (p->header.flag & BT_LEAF) {
					*cmpp = cmp;

					/* compute number of pages to split */
					if (flag & XT_INSERT) {
						if (p->header.nextindex ==
						    p->header.maxentry)
							nsplit++;
						else
							nsplit = 0;
						btstack->nsplit = nsplit;
					}

					/* save search result */
					btsp = btstack->top;
					btsp->bn = bn;
					btsp->index = index;
					btsp->mp = mp;

					/* init sequential access heuristics */
					btindex = jfs_ip->btindex;
					if (index == btindex ||
					    index == btindex + 1)
						jfs_ip->btorder = BT_SEQUENTIAL;
					else
						jfs_ip->btorder = BT_RANDOM;
					jfs_ip->btindex = index;

					return 0;
				}
				/* search hit - internal page:
				 * descend/search its child page
				 */
				if (index < p->header.nextindex - 1)
					next = offsetXAD(&p->xad[index + 1]);
				goto next;
			}

			if (cmp > 0) {
				base = index + 1;
				--lim;
			}
		}

		/*
		 *      search miss
		 *
		 * base is the smallest index with key (Kj) greater than
		 * search key (K) and may be zero or maxentry index.
		 */
		if (base < p->header.nextindex)
			next = offsetXAD(&p->xad[base]);
		/*
		 * search miss - leaf page:
		 *
		 * return location of entry (base) where new entry with
		 * search key K is to be inserted.
		 */
		if (p->header.flag & BT_LEAF) {
			*cmpp = cmp;

			/* compute number of pages to split */
			if (flag & XT_INSERT) {
				if (p->header.nextindex ==
				    p->header.maxentry)
					nsplit++;
				else
					nsplit = 0;
				btstack->nsplit = nsplit;
			}

			/* save search result */
			btsp = btstack->top;
			btsp->bn = bn;
			btsp->index = base;
			btsp->mp = mp;

			/* init sequential access heuristics */
			btindex = jfs_ip->btindex;
			if (base == btindex || base == btindex + 1)
				jfs_ip->btorder = BT_SEQUENTIAL;
			else
				jfs_ip->btorder = BT_RANDOM;
			jfs_ip->btindex = base;

			if (nextp)
				*nextp = next;

			return 0;
		}

		/*
		 * search miss - non-leaf page:
		 *
		 * if base is non-zero, decrement base by one to get the parent
		 * entry of the child page to search.
		 */
		index = base ? base - 1 : base;

		/*
		 * go down to child page
		 */
	      next:
		/* update number of pages to split */
		if (p->header.nextindex == p->header.maxentry)
			nsplit++;
		else
			nsplit = 0;

		/* push (bn, index) of the parent page/entry */
		BT_PUSH(btstack, bn, index);

		/* get the child page block number */
		bn = addressXAD(&p->xad[index]);

		/* unpin the parent page */
		XT_PUTPAGE(mp);
	}
}

/*
 *      xtInsert()
 *
 * function:
 *
 * parameter:
 *      tid     - transaction id;
 *      ip      - file object;
 *      xflag   - extent flag (XAD_NOTRECORDED):
 *      xoff    - extent offset;
 *      xlen    - extent length;
 *      xaddrp  - extent address pointer (in/out):
 *              if (*xaddrp)
 *                      caller allocated data extent at *xaddrp;
 *              else
 *                      allocate data extent and return its xaddr;
 *      flag    -
 *
 * return:
 */
int xtInsert(tid_t tid,		/* transaction id */
	     struct inode *ip, int xflag, s64 xoff, s32 xlen, s64 * xaddrp,
	     int flag)
{
	int rc = 0;
	s64 xaddr, hint;
	struct metapage *mp;	/* meta-page buffer */
	xtpage_t *p;		/* base B+-tree index page */
	s64 bn;
	int index, nextindex;
	struct btstack btstack;	/* traverse stack */
	struct xtsplit split;	/* split information */
	xad_t *xad;
	int cmp;
	s64 next;
	struct tlock *tlck;
	struct xtlock *xtlck;

	jfs_info("xtInsert: nxoff:0x%lx nxlen:0x%x", (ulong) xoff, xlen);

	/*
	 *      search for the entry location at which to insert:
	 *
	 * xtFastSearch() and xtSearch() both returns (leaf page
	 * pinned, index at which to insert).
	 * n.b. xtSearch() may return index of maxentry of
	 * the full page.
	 */
	if ((rc = xtSearch(ip, xoff, &next, &cmp, &btstack, XT_INSERT)))
		return rc;

	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

	/* This test must follow XT_GETSEARCH since mp must be valid if
	 * we branch to out: */
	if ((cmp == 0) || (next && (xlen > next - xoff))) {
		rc = -EEXIST;
		goto out;
	}

	/*
	 * allocate data extent requested
	 *
	 * allocation hint: last xad
	 */
	if ((xaddr = *xaddrp) == 0) {
		if (index > XTENTRYSTART) {
			xad = &p->xad[index - 1];
			hint = addressXAD(xad) + lengthXAD(xad) - 1;
		} else
			hint = 0;
		if ((rc = DQUOT_ALLOC_BLOCK(ip, xlen)))
			goto out;
		if ((rc = dbAlloc(ip, hint, (s64) xlen, &xaddr))) {
			DQUOT_FREE_BLOCK(ip, xlen);
			goto out;
		}
	}

	/*
	 *      insert entry for new extent
	 */
	xflag |= XAD_NEW;

	/*
	 *      if the leaf page is full, split the page and
	 *      propagate up the router entry for the new page from split
	 *
	 * The xtSplitUp() will insert the entry and unpin the leaf page.
	 */
	nextindex = le16_to_cpu(p->header.nextindex);
	if (nextindex == le16_to_cpu(p->header.maxentry)) {
		split.mp = mp;
		split.index = index;
		split.flag = xflag;
		split.off = xoff;
		split.len = xlen;
		split.addr = xaddr;
		split.pxdlist = NULL;
		if ((rc = xtSplitUp(tid, ip, &split, &btstack))) {
			/* undo data extent allocation */
			if (*xaddrp == 0) {
				dbFree(ip, xaddr, (s64) xlen);
				DQUOT_FREE_BLOCK(ip, xlen);
			}
			return rc;
		}

		*xaddrp = xaddr;
		return 0;
	}

	/*
	 *      insert the new entry into the leaf page
	 */
	/*
	 * acquire a transaction lock on the leaf page;
	 *
	 * action: xad insertion/extension;
	 */
	BT_MARK_DIRTY(mp, ip);

	/* if insert into middle, shift right remaining entries. */
	if (index < nextindex)
		memmove(&p->xad[index + 1], &p->xad[index],
			(nextindex - index) * sizeof(xad_t));

	/* insert the new entry: mark the entry NEW */
	xad = &p->xad[index];
	XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);

	/* advance next available entry index */
	p->header.nextindex =
	    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);

	/* Don't log it if there are no links to the file */
	if (!test_cflag(COMMIT_Nolink, ip)) {
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
		xtlck = (struct xtlock *) & tlck->lock;
		xtlck->lwm.offset =
		    (xtlck->lwm.offset) ? min(index,
					      (int)xtlck->lwm.offset) : index;
		xtlck->lwm.length =
		    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;
	}

	*xaddrp = xaddr;

      out:
	/* unpin the leaf page */
	XT_PUTPAGE(mp);

	return rc;
}


/*
 *      xtSplitUp()
 *
 * function:
 *      split full pages as propagating insertion up the tree
 *
 * parameter:
 *      tid     - transaction id;
 *      ip      - file object;
 *      split   - entry parameter descriptor;
 *      btstack - traverse stack from xtSearch()
 *
 * return:
 */
static int
xtSplitUp(tid_t tid,
	  struct inode *ip, struct xtsplit * split, struct btstack * btstack)
{
	int rc = 0;
	struct metapage *smp;
	xtpage_t *sp;		/* split page */
	struct metapage *rmp;
	s64 rbn;		/* new right page block number */
	struct metapage *rcmp;
	xtpage_t *rcp;		/* right child page */
	s64 rcbn;		/* right child page block number */
	int skip;		/* index of entry of insertion */
	int nextindex;		/* next available entry index of p */
	struct btframe *parent;	/* parent page entry on traverse stack */
	xad_t *xad;
	s64 xaddr;
	int xlen;
	int nsplit;		/* number of pages split */
	struct pxdlist pxdlist;
	pxd_t *pxd;
	struct tlock *tlck;
	struct xtlock *xtlck;

	smp = split->mp;
	sp = XT_PAGE(ip, smp);

	/* is inode xtree root extension/inline EA area free ? */
	if ((sp->header.flag & BT_ROOT) && (!S_ISDIR(ip->i_mode)) &&
	    (le16_to_cpu(sp->header.maxentry) < XTROOTMAXSLOT) &&
	    (JFS_IP(ip)->mode2 & INLINEEA)) {
		sp->header.maxentry = cpu_to_le16(XTROOTMAXSLOT);
		JFS_IP(ip)->mode2 &= ~INLINEEA;

		BT_MARK_DIRTY(smp, ip);
		/*
		 * acquire a transaction lock on the leaf page;
		 *
		 * action: xad insertion/extension;
		 */

		/* if insert into middle, shift right remaining entries. */
		skip = split->index;
		nextindex = le16_to_cpu(sp->header.nextindex);
		if (skip < nextindex)
			memmove(&sp->xad[skip + 1], &sp->xad[skip],
				(nextindex - skip) * sizeof(xad_t));

		/* insert the new entry: mark the entry NEW */
		xad = &sp->xad[skip];
		XT_PUTENTRY(xad, split->flag, split->off, split->len,
			    split->addr);

		/* advance next available entry index */
		sp->header.nextindex =
		    cpu_to_le16(le16_to_cpu(sp->header.nextindex) + 1);

		/* Don't log it if there are no links to the file */
		if (!test_cflag(COMMIT_Nolink, ip)) {
			tlck = txLock(tid, ip, smp, tlckXTREE | tlckGROW);
			xtlck = (struct xtlock *) & tlck->lock;
			xtlck->lwm.offset = (xtlck->lwm.offset) ?
			    min(skip, (int)xtlck->lwm.offset) : skip;
			xtlck->lwm.length =
			    le16_to_cpu(sp->header.nextindex) -
			    xtlck->lwm.offset;
		}

		return 0;
	}

	/*
	 * allocate new index blocks to cover index page split(s)
	 *
	 * allocation hint: ?
	 */
	if (split->pxdlist == NULL) {
		nsplit = btstack->nsplit;
		split->pxdlist = &pxdlist;
		pxdlist.maxnpxd = pxdlist.npxd = 0;
		pxd = &pxdlist.pxd[0];
		xlen = JFS_SBI(ip->i_sb)->nbperpage;
		for (; nsplit > 0; nsplit--, pxd++) {
			if ((rc = dbAlloc(ip, (s64) 0, (s64) xlen, &xaddr))
			    == 0) {
				PXDaddress(pxd, xaddr);
				PXDlength(pxd, xlen);

				pxdlist.maxnpxd++;

				continue;
			}

			/* undo allocation */

			XT_PUTPAGE(smp);
			return rc;
		}
	}

	/*
	 * Split leaf page <sp> into <sp> and a new right page <rp>.
	 *
	 * The split routines insert the new entry into the leaf page,
	 * and acquire txLock as appropriate.
	 * return <rp> pinned and its block number <rpbn>.
	 */
	rc = (sp->header.flag & BT_ROOT) ?
	    xtSplitRoot(tid, ip, split, &rmp) :
	    xtSplitPage(tid, ip, split, &rmp, &rbn);

	XT_PUTPAGE(smp);

	if (rc)
		return -EIO;
	/*
	 * propagate up the router entry for the leaf page just split
	 *
	 * insert a router entry for the new page into the parent page,
	 * propagate the insert/split up the tree by walking back the stack
	 * of (bn of parent page, index of child page entry in parent page)
	 * that were traversed during the search for the page that split.
	 *
	 * the propagation of insert/split up the tree stops if the root
	 * splits or the page inserted into doesn't have to split to hold
	 * the new entry.
	 *
	 * the parent entry for the split page remains the same, and
	 * a new entry is inserted at its right with the first key and
	 * block number of the new right page.
	 *
	 * There are a maximum of 3 pages pinned at any time:
	 * right child, left parent and right parent (when the parent splits)
	 * to keep the child page pinned while working on the parent.
	 * make sure that all pins are released at exit.
	 */
	while ((parent = BT_POP(btstack)) != NULL) {
		/* parent page specified by stack frame <parent> */

		/* keep current child pages <rcp> pinned */
		rcmp = rmp;
		rcbn = rbn;
		rcp = XT_PAGE(ip, rcmp);

		/*
		 * insert router entry in parent for new right child page <rp>
		 */
		/* get/pin the parent page <sp> */
		XT_GETPAGE(ip, parent->bn, smp, PSIZE, sp, rc);
		if (rc) {
			XT_PUTPAGE(rcmp);
			return rc;
		}

		/*
		 * The new key entry goes ONE AFTER the index of parent entry,
		 * because the split was to the right.
		 */
		skip = parent->index + 1;

		/*
		 * split or shift right remaining entries of the parent page
		 */
		nextindex = le16_to_cpu(sp->header.nextindex);
		/*
		 * parent page is full - split the parent page
		 */
		if (nextindex == le16_to_cpu(sp->header.maxentry)) {
			/* init for parent page split */
			split->mp = smp;
			split->index = skip;	/* index at insert */
			split->flag = XAD_NEW;
			split->off = offsetXAD(&rcp->xad[XTENTRYSTART]);
			split->len = JFS_SBI(ip->i_sb)->nbperpage;
			split->addr = rcbn;

			/* unpin previous right child page */
			XT_PUTPAGE(rcmp);

			/* The split routines insert the new entry,
			 * and acquire txLock as appropriate.
			 * return <rp> pinned and its block number <rpbn>.
			 */
			rc = (sp->header.flag & BT_ROOT) ?
			    xtSplitRoot(tid, ip, split, &rmp) :
			    xtSplitPage(tid, ip, split, &rmp, &rbn);
			if (rc) {
				XT_PUTPAGE(smp);
				return rc;
			}

			XT_PUTPAGE(smp);
			/* keep new child page <rp> pinned */
		}
		/*
		 * parent page is not full - insert in parent page
		 */
		else {
			/*
			 * insert router entry in parent for the right child
			 * page from the first entry of the right child page:
			 */
			/*
			 * acquire a transaction lock on the parent page;
			 *
			 * action: router xad insertion;
			 */
			BT_MARK_DIRTY(smp, ip);

			/*
			 * if insert into middle, shift right remaining entries
			 */
			if (skip < nextindex)
				memmove(&sp->xad[skip + 1], &sp->xad[skip],
					(nextindex -
					 skip) << L2XTSLOTSIZE);

			/* insert the router entry */
			xad = &sp->xad[skip];
			XT_PUTENTRY(xad, XAD_NEW,
				    offsetXAD(&rcp->xad[XTENTRYSTART]),
				    JFS_SBI(ip->i_sb)->nbperpage, rcbn);

			/* advance next available entry index. */
			sp->header.nextindex =
			    cpu_to_le16(le16_to_cpu(sp->header.nextindex) +
					1);

			/* Don't log it if there are no links to the file */
			if (!test_cflag(COMMIT_Nolink, ip)) {
				tlck = txLock(tid, ip, smp,
					      tlckXTREE | tlckGROW);
				xtlck = (struct xtlock *) & tlck->lock;
				xtlck->lwm.offset = (xtlck->lwm.offset) ?
				    min(skip, (int)xtlck->lwm.offset) : skip;
				xtlck->lwm.length =
				    le16_to_cpu(sp->header.nextindex) -
				    xtlck->lwm.offset;
			}

			/* unpin parent page */
			XT_PUTPAGE(smp);

			/* exit propagate up */
			break;
		}
	}

	/* unpin current right page */
	XT_PUTPAGE(rmp);

	return 0;
}


/*
 *      xtSplitPage()
 *
 * function:
 *      split a full non-root page into
 *      original/split/left page and new right page
 *      i.e., the original/split page remains as left page.
 *
 * parameter:
 *      int		tid,
 *      struct inode    *ip,
 *      struct xtsplit  *split,
 *      struct metapage	**rmpp,
 *      u64		*rbnp,
 *
 * return:
 *      Pointer to page in which to insert or NULL on error.
 */
static int
xtSplitPage(tid_t tid, struct inode *ip,
	    struct xtsplit * split, struct metapage ** rmpp, s64 * rbnp)
{
	int rc = 0;
	struct metapage *smp;
	xtpage_t *sp;
	struct metapage *rmp;
	xtpage_t *rp;		/* new right page allocated */
	s64 rbn;		/* new right page block number */
	struct metapage *mp;
	xtpage_t *p;
	s64 nextbn;
	int skip, maxentry, middle, righthalf, n;
	xad_t *xad;
	struct pxdlist *pxdlist;
	pxd_t *pxd;
	struct tlock *tlck;
	struct xtlock *sxtlck = NULL, *rxtlck = NULL;
	int quota_allocation = 0;

	smp = split->mp;
	sp = XT_PAGE(ip, smp);

	INCREMENT(xtStat.split);

	pxdlist = split->pxdlist;
	pxd = &pxdlist->pxd[pxdlist->npxd];
	pxdlist->npxd++;
	rbn = addressPXD(pxd);

	/* Allocate blocks to quota. */
       if (DQUOT_ALLOC_BLOCK(ip, lengthPXD(pxd))) {
	       rc = -EDQUOT;
	       goto clean_up;
	}

	quota_allocation += lengthPXD(pxd);

	/*
	 * allocate the new right page for the split
	 */
	rmp = get_metapage(ip, rbn, PSIZE, 1);
	if (rmp == NULL) {
		rc = -EIO;
		goto clean_up;
	}

	jfs_info("xtSplitPage: ip:0x%p smp:0x%p rmp:0x%p", ip, smp, rmp);

	BT_MARK_DIRTY(rmp, ip);
	/*
	 * action: new page;
	 */

	rp = (xtpage_t *) rmp->data;
	rp->header.self = *pxd;
	rp->header.flag = sp->header.flag & BT_TYPE;
	rp->header.maxentry = sp->header.maxentry;	/* little-endian */
	rp->header.nextindex = cpu_to_le16(XTENTRYSTART);

	BT_MARK_DIRTY(smp, ip);
	/* Don't log it if there are no links to the file */
	if (!test_cflag(COMMIT_Nolink, ip)) {
		/*
		 * acquire a transaction lock on the new right page;
		 */
		tlck = txLock(tid, ip, rmp, tlckXTREE | tlckNEW);
		rxtlck = (struct xtlock *) & tlck->lock;
		rxtlck->lwm.offset = XTENTRYSTART;
		/*
		 * acquire a transaction lock on the split page
		 */
		tlck = txLock(tid, ip, smp, tlckXTREE | tlckGROW);
		sxtlck = (struct xtlock *) & tlck->lock;
	}

	/*
	 * initialize/update sibling pointers of <sp> and <rp>
	 */
	nextbn = le64_to_cpu(sp->header.next);
	rp->header.next = cpu_to_le64(nextbn);
	rp->header.prev = cpu_to_le64(addressPXD(&sp->header.self));
	sp->header.next = cpu_to_le64(rbn);

	skip = split->index;

	/*
	 *      sequential append at tail (after last entry of last page)
	 *
	 * if splitting the last page on a level because of appending
	 * a entry to it (skip is maxentry), it's likely that the access is
	 * sequential. adding an empty page on the side of the level is less
	 * work and can push the fill factor much higher than normal.
	 * if we're wrong it's no big deal -  we will do the split the right
	 * way next time.
	 * (it may look like it's equally easy to do a similar hack for
	 * reverse sorted data, that is, split the tree left, but it's not.
	 * Be my guest.)
	 */
	if (nextbn == 0 && skip == le16_to_cpu(sp->header.maxentry)) {
		/*
		 * acquire a transaction lock on the new/right page;
		 *
		 * action: xad insertion;
		 */
		/* insert entry at the first entry of the new right page */
		xad = &rp->xad[XTENTRYSTART];
		XT_PUTENTRY(xad, split->flag, split->off, split->len,
			    split->addr);

		rp->header.nextindex = cpu_to_le16(XTENTRYSTART + 1);

		if (!test_cflag(COMMIT_Nolink, ip)) {
			/* rxtlck->lwm.offset = XTENTRYSTART; */
			rxtlck->lwm.length = 1;
		}

		*rmpp = rmp;
		*rbnp = rbn;

		jfs_info("xtSplitPage: sp:0x%p rp:0x%p", sp, rp);
		return 0;
	}

	/*
	 *      non-sequential insert (at possibly middle page)
	 */

	/*
	 * update previous pointer of old next/right page of <sp>
	 */
	if (nextbn != 0) {
		XT_GETPAGE(ip, nextbn, mp, PSIZE, p, rc);
		if (rc) {
			XT_PUTPAGE(rmp);
			goto clean_up;
		}

		BT_MARK_DIRTY(mp, ip);
		/*
		 * acquire a transaction lock on the next page;
		 *
		 * action:sibling pointer update;
		 */
		if (!test_cflag(COMMIT_Nolink, ip))
			tlck = txLock(tid, ip, mp, tlckXTREE | tlckRELINK);

		p->header.prev = cpu_to_le64(rbn);

		/* sibling page may have been updated previously, or
		 * it may be updated later;
		 */

		XT_PUTPAGE(mp);
	}

	/*
	 * split the data between the split and new/right pages
	 */
	maxentry = le16_to_cpu(sp->header.maxentry);
	middle = maxentry >> 1;
	righthalf = maxentry - middle;

	/*
	 * skip index in old split/left page - insert into left page:
	 */
	if (skip <= middle) {
		/* move right half of split page to the new right page */
		memmove(&rp->xad[XTENTRYSTART], &sp->xad[middle],
			righthalf << L2XTSLOTSIZE);

		/* shift right tail of left half to make room for new entry */
		if (skip < middle)
			memmove(&sp->xad[skip + 1], &sp->xad[skip],
				(middle - skip) << L2XTSLOTSIZE);

		/* insert new entry */
		xad = &sp->xad[skip];
		XT_PUTENTRY(xad, split->flag, split->off, split->len,
			    split->addr);

		/* update page header */
		sp->header.nextindex = cpu_to_le16(middle + 1);
		if (!test_cflag(COMMIT_Nolink, ip)) {
			sxtlck->lwm.offset = (sxtlck->lwm.offset) ?
			    min(skip, (int)sxtlck->lwm.offset) : skip;
		}

		rp->header.nextindex =
		    cpu_to_le16(XTENTRYSTART + righthalf);
	}
	/*
	 * skip index in new right page - insert into right page:
	 */
	else {
		/* move left head of right half to right page */
		n = skip - middle;
		memmove(&rp->xad[XTENTRYSTART], &sp->xad[middle],
			n << L2XTSLOTSIZE);

		/* insert new entry */
		n += XTENTRYSTART;
		xad = &rp->xad[n];
		XT_PUTENTRY(xad, split->flag, split->off, split->len,
			    split->addr);

		/* move right tail of right half to right page */
		if (skip < maxentry)
			memmove(&rp->xad[n + 1], &sp->xad[skip],
				(maxentry - skip) << L2XTSLOTSIZE);

		/* update page header */
		sp->header.nextindex = cpu_to_le16(middle);
		if (!test_cflag(COMMIT_Nolink, ip)) {
			sxtlck->lwm.offset = (sxtlck->lwm.offset) ?
			    min(middle, (int)sxtlck->lwm.offset) : middle;
		}

		rp->header.nextindex = cpu_to_le16(XTENTRYSTART +
						   righthalf + 1);
	}

	if (!test_cflag(COMMIT_Nolink, ip)) {
		sxtlck->lwm.length = le16_to_cpu(sp->header.nextindex) -
		    sxtlck->lwm.offset;

		/* rxtlck->lwm.offset = XTENTRYSTART; */
		rxtlck->lwm.length = le16_to_cpu(rp->header.nextindex) -
		    XTENTRYSTART;
	}

	*rmpp = rmp;
	*rbnp = rbn;

	jfs_info("xtSplitPage: sp:0x%p rp:0x%p", sp, rp);
	return rc;

      clean_up:

	/* Rollback quota allocation. */
	if (quota_allocation)
		DQUOT_FREE_BLOCK(ip, quota_allocation);

	return (rc);
}


/*
 *      xtSplitRoot()
 *
 * function:
 *      split the full root page into
 *      original/root/split page and new right page
 *      i.e., root remains fixed in tree anchor (inode) and
 *      the root is copied to a single new right child page
 *      since root page << non-root page, and
 *      the split root page contains a single entry for the
 *      new right child page.
 *
 * parameter:
 *      int		tid,
 *      struct inode    *ip,
 *      struct xtsplit  *split,
 *      struct metapage	**rmpp)
 *
 * return:
 *      Pointer to page in which to insert or NULL on error.
 */
static int
xtSplitRoot(tid_t tid,
	    struct inode *ip, struct xtsplit * split, struct metapage ** rmpp)
{
	xtpage_t *sp;
	struct metapage *rmp;
	xtpage_t *rp;
	s64 rbn;
	int skip, nextindex;
	xad_t *xad;
	pxd_t *pxd;
	struct pxdlist *pxdlist;
	struct tlock *tlck;
	struct xtlock *xtlck;

	sp = &JFS_IP(ip)->i_xtroot;

	INCREMENT(xtStat.split);

	/*
	 *      allocate a single (right) child page
	 */
	pxdlist = split->pxdlist;
	pxd = &pxdlist->pxd[pxdlist->npxd];
	pxdlist->npxd++;
	rbn = addressPXD(pxd);
	rmp = get_metapage(ip, rbn, PSIZE, 1);
	if (rmp == NULL)
		return -EIO;

	/* Allocate blocks to quota. */
	if (DQUOT_ALLOC_BLOCK(ip, lengthPXD(pxd))) {
		release_metapage(rmp);
		return -EDQUOT;
	}

	jfs_info("xtSplitRoot: ip:0x%p rmp:0x%p", ip, rmp);

	/*
	 * acquire a transaction lock on the new right page;
	 *
	 * action: new page;
	 */
	BT_MARK_DIRTY(rmp, ip);

	rp = (xtpage_t *) rmp->data;
	rp->header.flag =
	    (sp->header.flag & BT_LEAF) ? BT_LEAF : BT_INTERNAL;
	rp->header.self = *pxd;
	rp->header.nextindex = cpu_to_le16(XTENTRYSTART);
	rp->header.maxentry = cpu_to_le16(PSIZE >> L2XTSLOTSIZE);

	/* initialize sibling pointers */
	rp->header.next = 0;
	rp->header.prev = 0;

	/*
	 * copy the in-line root page into new right page extent
	 */
	nextindex = le16_to_cpu(sp->header.maxentry);
	memmove(&rp->xad[XTENTRYSTART], &sp->xad[XTENTRYSTART],
		(nextindex - XTENTRYSTART) << L2XTSLOTSIZE);

	/*
	 * insert the new entry into the new right/child page
	 * (skip index in the new right page will not change)
	 */
	skip = split->index;
	/* if insert into middle, shift right remaining entries */
	if (skip != nextindex)
		memmove(&rp->xad[skip + 1], &rp->xad[skip],
			(nextindex - skip) * sizeof(xad_t));

	xad = &rp->xad[skip];
	XT_PUTENTRY(xad, split->flag, split->off, split->len, split->addr);

	/* update page header */
	rp->header.nextindex = cpu_to_le16(nextindex + 1);

	if (!test_cflag(COMMIT_Nolink, ip)) {
		tlck = txLock(tid, ip, rmp, tlckXTREE | tlckNEW);
		xtlck = (struct xtlock *) & tlck->lock;
		xtlck->lwm.offset = XTENTRYSTART;
		xtlck->lwm.length = le16_to_cpu(rp->header.nextindex) -
		    XTENTRYSTART;
	}

	/*
	 *      reset the root
	 *
	 * init root with the single entry for the new right page
	 * set the 1st entry offset to 0, which force the left-most key
	 * at any level of the tree to be less than any search key.
	 */
	/*
	 * acquire a transaction lock on the root page (in-memory inode);
	 *
	 * action: root split;
	 */
	BT_MARK_DIRTY(split->mp, ip);

	xad = &sp->xad[XTENTRYSTART];
	XT_PUTENTRY(xad, XAD_NEW, 0, JFS_SBI(ip->i_sb)->nbperpage, rbn);

	/* update page header of root */
	sp->header.flag &= ~BT_LEAF;
	sp->header.flag |= BT_INTERNAL;

	sp->header.nextindex = cpu_to_le16(XTENTRYSTART + 1);

	if (!test_cflag(COMMIT_Nolink, ip)) {
		tlck = txLock(tid, ip, split->mp, tlckXTREE | tlckGROW);
		xtlck = (struct xtlock *) & tlck->lock;
		xtlck->lwm.offset = XTENTRYSTART;
		xtlck->lwm.length = 1;
	}

	*rmpp = rmp;

	jfs_info("xtSplitRoot: sp:0x%p rp:0x%p", sp, rp);
	return 0;
}


/*
 *      xtExtend()
 *
 * function: extend in-place;
 *
 * note: existing extent may or may not have been committed.
 * caller is responsible for pager buffer cache update, and
 * working block allocation map update;
 * update pmap: alloc whole extended extent;
 */
int xtExtend(tid_t tid,		/* transaction id */
	     struct inode *ip, s64 xoff,	/* delta extent offset */
	     s32 xlen,		/* delta extent length */
	     int flag)
{
	int rc = 0;
	int cmp;
	struct metapage *mp;	/* meta-page buffer */
	xtpage_t *p;		/* base B+-tree index page */
	s64 bn;
	int index, nextindex, len;
	struct btstack btstack;	/* traverse stack */
	struct xtsplit split;	/* split information */
	xad_t *xad;
	s64 xaddr;
	struct tlock *tlck;
	struct xtlock *xtlck = NULL;

	jfs_info("xtExtend: nxoff:0x%lx nxlen:0x%x", (ulong) xoff, xlen);

	/* there must exist extent to be extended */
	if ((rc = xtSearch(ip, xoff - 1, NULL, &cmp, &btstack, XT_INSERT)))
		return rc;

	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

	if (cmp != 0) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb, "xtExtend: xtSearch did not find extent");
		return -EIO;
	}

	/* extension must be contiguous */
	xad = &p->xad[index];
	if ((offsetXAD(xad) + lengthXAD(xad)) != xoff) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb, "xtExtend: extension is not contiguous");
		return -EIO;
	}

	/*
	 * acquire a transaction lock on the leaf page;
	 *
	 * action: xad insertion/extension;
	 */
	BT_MARK_DIRTY(mp, ip);
	if (!test_cflag(COMMIT_Nolink, ip)) {
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
		xtlck = (struct xtlock *) & tlck->lock;
	}

	/* extend will overflow extent ? */
	xlen = lengthXAD(xad) + xlen;
	if ((len = xlen - MAXXLEN) <= 0)
		goto extendOld;

	/*
	 *      extent overflow: insert entry for new extent
	 */
//insertNew:
	xoff = offsetXAD(xad) + MAXXLEN;
	xaddr = addressXAD(xad) + MAXXLEN;
	nextindex = le16_to_cpu(p->header.nextindex);

	/*
	 *      if the leaf page is full, insert the new entry and
	 *      propagate up the router entry for the new page from split
	 *
	 * The xtSplitUp() will insert the entry and unpin the leaf page.
	 */
	if (nextindex == le16_to_cpu(p->header.maxentry)) {
		/* xtSpliUp() unpins leaf pages */
		split.mp = mp;
		split.index = index + 1;
		split.flag = XAD_NEW;
		split.off = xoff;	/* split offset */
		split.len = len;
		split.addr = xaddr;
		split.pxdlist = NULL;
		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
			return rc;

		/* get back old page */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;
		/*
		 * if leaf root has been split, original root has been
		 * copied to new child page, i.e., original entry now
		 * resides on the new child page;
		 */
		if (p->header.flag & BT_INTERNAL) {
			ASSERT(p->header.nextindex ==
			       cpu_to_le16(XTENTRYSTART + 1));
			xad = &p->xad[XTENTRYSTART];
			bn = addressXAD(xad);
			XT_PUTPAGE(mp);

			/* get new child page */
			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
			if (rc)
				return rc;

			BT_MARK_DIRTY(mp, ip);
			if (!test_cflag(COMMIT_Nolink, ip)) {
				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
				xtlck = (struct xtlock *) & tlck->lock;
			}
		}
	}
	/*
	 *      insert the new entry into the leaf page
	 */
	else {
		/* insert the new entry: mark the entry NEW */
		xad = &p->xad[index + 1];
		XT_PUTENTRY(xad, XAD_NEW, xoff, len, xaddr);

		/* advance next available entry index */
		p->header.nextindex =
		    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
	}

	/* get back old entry */
	xad = &p->xad[index];
	xlen = MAXXLEN;

	/*
	 * extend old extent
	 */
      extendOld:
	XADlength(xad, xlen);
	if (!(xad->flag & XAD_NEW))
		xad->flag |= XAD_EXTENDED;

	if (!test_cflag(COMMIT_Nolink, ip)) {
		xtlck->lwm.offset =
		    (xtlck->lwm.offset) ? min(index,
					      (int)xtlck->lwm.offset) : index;
		xtlck->lwm.length =
		    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;
	}

	/* unpin the leaf page */
	XT_PUTPAGE(mp);

	return rc;
}

#ifdef _NOTYET
/*
 *      xtTailgate()
 *
 * function: split existing 'tail' extent
 *      (split offset >= start offset of tail extent), and
 *      relocate and extend the split tail half;
 *
 * note: existing extent may or may not have been committed.
 * caller is responsible for pager buffer cache update, and
 * working block allocation map update;
 * update pmap: free old split tail extent, alloc new extent;
 */
int xtTailgate(tid_t tid,		/* transaction id */
	       struct inode *ip, s64 xoff,	/* split/new extent offset */
	       s32 xlen,	/* new extent length */
	       s64 xaddr,	/* new extent address */
	       int flag)
{
	int rc = 0;
	int cmp;
	struct metapage *mp;	/* meta-page buffer */
	xtpage_t *p;		/* base B+-tree index page */
	s64 bn;
	int index, nextindex, llen, rlen;
	struct btstack btstack;	/* traverse stack */
	struct xtsplit split;	/* split information */
	xad_t *xad;
	struct tlock *tlck;
	struct xtlock *xtlck = 0;
	struct tlock *mtlck;
	struct maplock *pxdlock;

/*
printf("xtTailgate: nxoff:0x%lx nxlen:0x%x nxaddr:0x%lx\n",
        (ulong)xoff, xlen, (ulong)xaddr);
*/

	/* there must exist extent to be tailgated */
	if ((rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, XT_INSERT)))
		return rc;

	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

	if (cmp != 0) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb, "xtTailgate: couldn't find extent");
		return -EIO;
	}

	/* entry found must be last entry */
	nextindex = le16_to_cpu(p->header.nextindex);
	if (index != nextindex - 1) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb,
			  "xtTailgate: the entry found is not the last entry");
		return -EIO;
	}

	BT_MARK_DIRTY(mp, ip);
	/*
	 * acquire tlock of the leaf page containing original entry
	 */
	if (!test_cflag(COMMIT_Nolink, ip)) {
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
		xtlck = (struct xtlock *) & tlck->lock;
	}

	/* completely replace extent ? */
	xad = &p->xad[index];
/*
printf("xtTailgate: xoff:0x%lx xlen:0x%x xaddr:0x%lx\n",
        (ulong)offsetXAD(xad), lengthXAD(xad), (ulong)addressXAD(xad));
*/
	if ((llen = xoff - offsetXAD(xad)) == 0)
		goto updateOld;

	/*
	 *      partially replace extent: insert entry for new extent
	 */
//insertNew:
	/*
	 *      if the leaf page is full, insert the new entry and
	 *      propagate up the router entry for the new page from split
	 *
	 * The xtSplitUp() will insert the entry and unpin the leaf page.
	 */
	if (nextindex == le16_to_cpu(p->header.maxentry)) {
		/* xtSpliUp() unpins leaf pages */
		split.mp = mp;
		split.index = index + 1;
		split.flag = XAD_NEW;
		split.off = xoff;	/* split offset */
		split.len = xlen;
		split.addr = xaddr;
		split.pxdlist = NULL;
		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
			return rc;

		/* get back old page */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;
		/*
		 * if leaf root has been split, original root has been
		 * copied to new child page, i.e., original entry now
		 * resides on the new child page;
		 */
		if (p->header.flag & BT_INTERNAL) {
			ASSERT(p->header.nextindex ==
			       cpu_to_le16(XTENTRYSTART + 1));
			xad = &p->xad[XTENTRYSTART];
			bn = addressXAD(xad);
			XT_PUTPAGE(mp);

			/* get new child page */
			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
			if (rc)
				return rc;

			BT_MARK_DIRTY(mp, ip);
			if (!test_cflag(COMMIT_Nolink, ip)) {
				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
				xtlck = (struct xtlock *) & tlck->lock;
			}
		}
	}
	/*
	 *      insert the new entry into the leaf page
	 */
	else {
		/* insert the new entry: mark the entry NEW */
		xad = &p->xad[index + 1];
		XT_PUTENTRY(xad, XAD_NEW, xoff, xlen, xaddr);

		/* advance next available entry index */
		p->header.nextindex =
		    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
	}

	/* get back old XAD */
	xad = &p->xad[index];

	/*
	 * truncate/relocate old extent at split offset
	 */
      updateOld:
	/* update dmap for old/committed/truncated extent */
	rlen = lengthXAD(xad) - llen;
	if (!(xad->flag & XAD_NEW)) {
		/* free from PWMAP at commit */
		if (!test_cflag(COMMIT_Nolink, ip)) {
			mtlck = txMaplock(tid, ip, tlckMAP);
			pxdlock = (struct maplock *) & mtlck->lock;
			pxdlock->flag = mlckFREEPXD;
			PXDaddress(&pxdlock->pxd, addressXAD(xad) + llen);
			PXDlength(&pxdlock->pxd, rlen);
			pxdlock->index = 1;
		}
	} else
		/* free from WMAP */
		dbFree(ip, addressXAD(xad) + llen, (s64) rlen);

	if (llen)
		/* truncate */
		XADlength(xad, llen);
	else
		/* replace */
		XT_PUTENTRY(xad, XAD_NEW, xoff, xlen, xaddr);

	if (!test_cflag(COMMIT_Nolink, ip)) {
		xtlck->lwm.offset = (xtlck->lwm.offset) ?
		    min(index, (int)xtlck->lwm.offset) : index;
		xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
		    xtlck->lwm.offset;
	}

	/* unpin the leaf page */
	XT_PUTPAGE(mp);

	return rc;
}
#endif /* _NOTYET */

/*
 *      xtUpdate()
 *
 * function: update XAD;
 *
 *      update extent for allocated_but_not_recorded or
 *      compressed extent;
 *
 * parameter:
 *      nxad    - new XAD;
 *                logical extent of the specified XAD must be completely
 *                contained by an existing XAD;
 */
int xtUpdate(tid_t tid, struct inode *ip, xad_t * nxad)
{				/* new XAD */
	int rc = 0;
	int cmp;
	struct metapage *mp;	/* meta-page buffer */
	xtpage_t *p;		/* base B+-tree index page */
	s64 bn;
	int index0, index, newindex, nextindex;
	struct btstack btstack;	/* traverse stack */
	struct xtsplit split;	/* split information */
	xad_t *xad, *lxad, *rxad;
	int xflag;
	s64 nxoff, xoff;
	int nxlen, xlen, lxlen, rxlen;
	s64 nxaddr, xaddr;
	struct tlock *tlck;
	struct xtlock *xtlck = NULL;
	int newpage = 0;

	/* there must exist extent to be tailgated */
	nxoff = offsetXAD(nxad);
	nxlen = lengthXAD(nxad);
	nxaddr = addressXAD(nxad);

	if ((rc = xtSearch(ip, nxoff, NULL, &cmp, &btstack, XT_INSERT)))
		return rc;

	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index0);

	if (cmp != 0) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb, "xtUpdate: Could not find extent");
		return -EIO;
	}

	BT_MARK_DIRTY(mp, ip);
	/*
	 * acquire tlock of the leaf page containing original entry
	 */
	if (!test_cflag(COMMIT_Nolink, ip)) {
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
		xtlck = (struct xtlock *) & tlck->lock;
	}

	xad = &p->xad[index0];
	xflag = xad->flag;
	xoff = offsetXAD(xad);
	xlen = lengthXAD(xad);
	xaddr = addressXAD(xad);

	/* nXAD must be completely contained within XAD */
	if ((xoff > nxoff) ||
	    (nxoff + nxlen > xoff + xlen)) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb,
			  "xtUpdate: nXAD in not completely contained within XAD");
		return -EIO;
	}

	index = index0;
	newindex = index + 1;
	nextindex = le16_to_cpu(p->header.nextindex);

#ifdef  _JFS_WIP_NOCOALESCE
	if (xoff < nxoff)
		goto updateRight;

	/*
	 * replace XAD with nXAD
	 */
      replace:			/* (nxoff == xoff) */
	if (nxlen == xlen) {
		/* replace XAD with nXAD:recorded */
		*xad = *nxad;
		xad->flag = xflag & ~XAD_NOTRECORDED;

		goto out;
	} else			/* (nxlen < xlen) */
		goto updateLeft;
#endif				/* _JFS_WIP_NOCOALESCE */

/* #ifdef _JFS_WIP_COALESCE */
	if (xoff < nxoff)
		goto coalesceRight;

	/*
	 * coalesce with left XAD
	 */
//coalesceLeft: /* (xoff == nxoff) */
	/* is XAD first entry of page ? */
	if (index == XTENTRYSTART)
		goto replace;

	/* is nXAD logically and physically contiguous with lXAD ? */
	lxad = &p->xad[index - 1];
	lxlen = lengthXAD(lxad);
	if (!(lxad->flag & XAD_NOTRECORDED) &&
	    (nxoff == offsetXAD(lxad) + lxlen) &&
	    (nxaddr == addressXAD(lxad) + lxlen) &&
	    (lxlen + nxlen < MAXXLEN)) {
		/* extend right lXAD */
		index0 = index - 1;
		XADlength(lxad, lxlen + nxlen);

		/* If we just merged two extents together, need to make sure the
		 * right extent gets logged.  If the left one is marked XAD_NEW,
		 * then we know it will be logged.  Otherwise, mark as
		 * XAD_EXTENDED
		 */
		if (!(lxad->flag & XAD_NEW))
			lxad->flag |= XAD_EXTENDED;

		if (xlen > nxlen) {
			/* truncate XAD */
			XADoffset(xad, xoff + nxlen);
			XADlength(xad, xlen - nxlen);
			XADaddress(xad, xaddr + nxlen);
			goto out;
		} else {	/* (xlen == nxlen) */

			/* remove XAD */
			if (index < nextindex - 1)
				memmove(&p->xad[index], &p->xad[index + 1],
					(nextindex - index -
					 1) << L2XTSLOTSIZE);

			p->header.nextindex =
			    cpu_to_le16(le16_to_cpu(p->header.nextindex) -
					1);

			index = index0;
			newindex = index + 1;
			nextindex = le16_to_cpu(p->header.nextindex);
			xoff = nxoff = offsetXAD(lxad);
			xlen = nxlen = lxlen + nxlen;
			xaddr = nxaddr = addressXAD(lxad);
			goto coalesceRight;
		}
	}

	/*
	 * replace XAD with nXAD
	 */
      replace:			/* (nxoff == xoff) */
	if (nxlen == xlen) {
		/* replace XAD with nXAD:recorded */
		*xad = *nxad;
		xad->flag = xflag & ~XAD_NOTRECORDED;

		goto coalesceRight;
	} else			/* (nxlen < xlen) */
		goto updateLeft;

	/*
	 * coalesce with right XAD
	 */
      coalesceRight:		/* (xoff <= nxoff) */
	/* is XAD last entry of page ? */
	if (newindex == nextindex) {
		if (xoff == nxoff)
			goto out;
		goto updateRight;
	}

	/* is nXAD logically and physically contiguous with rXAD ? */
	rxad = &p->xad[index + 1];
	rxlen = lengthXAD(rxad);
	if (!(rxad->flag & XAD_NOTRECORDED) &&
	    (nxoff + nxlen == offsetXAD(rxad)) &&
	    (nxaddr + nxlen == addressXAD(rxad)) &&
	    (rxlen + nxlen < MAXXLEN)) {
		/* extend left rXAD */
		XADoffset(rxad, nxoff);
		XADlength(rxad, rxlen + nxlen);
		XADaddress(rxad, nxaddr);

		/* If we just merged two extents together, need to make sure
		 * the left extent gets logged.  If the right one is marked
		 * XAD_NEW, then we know it will be logged.  Otherwise, mark as
		 * XAD_EXTENDED
		 */
		if (!(rxad->flag & XAD_NEW))
			rxad->flag |= XAD_EXTENDED;

		if (xlen > nxlen)
			/* truncate XAD */
			XADlength(xad, xlen - nxlen);
		else {		/* (xlen == nxlen) */

			/* remove XAD */
			memmove(&p->xad[index], &p->xad[index + 1],
				(nextindex - index - 1) << L2XTSLOTSIZE);

			p->header.nextindex =
			    cpu_to_le16(le16_to_cpu(p->header.nextindex) -
					1);
		}

		goto out;
	} else if (xoff == nxoff)
		goto out;

	if (xoff >= nxoff) {
		XT_PUTPAGE(mp);
		jfs_error(ip->i_sb, "xtUpdate: xoff >= nxoff");
		return -EIO;
	}
/* #endif _JFS_WIP_COALESCE */

	/*
	 * split XAD into (lXAD, nXAD):
	 *
	 *          |---nXAD--->
	 * --|----------XAD----------|--
	 *   |-lXAD-|
	 */
      updateRight:		/* (xoff < nxoff) */
	/* truncate old XAD as lXAD:not_recorded */
	xad = &p->xad[index];
	XADlength(xad, nxoff - xoff);

	/* insert nXAD:recorded */
	if (nextindex == le16_to_cpu(p->header.maxentry)) {

		/* xtSpliUp() unpins leaf pages */
		split.mp = mp;
		split.index = newindex;
		split.flag = xflag & ~XAD_NOTRECORDED;
		split.off = nxoff;
		split.len = nxlen;
		split.addr = nxaddr;
		split.pxdlist = NULL;
		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
			return rc;

		/* get back old page */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;
		/*
		 * if leaf root has been split, original root has been
		 * copied to new child page, i.e., original entry now
		 * resides on the new child page;
		 */
		if (p->header.flag & BT_INTERNAL) {
			ASSERT(p->header.nextindex ==
			       cpu_to_le16(XTENTRYSTART + 1));
			xad = &p->xad[XTENTRYSTART];
			bn = addressXAD(xad);
			XT_PUTPAGE(mp);

			/* get new child page */
			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
			if (rc)
				return rc;

			BT_MARK_DIRTY(mp, ip);
			if (!test_cflag(COMMIT_Nolink, ip)) {
				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
				xtlck = (struct xtlock *) & tlck->lock;
			}
		} else {
			/* is nXAD on new page ? */
			if (newindex >
			    (le16_to_cpu(p->header.maxentry) >> 1)) {
				newindex =
				    newindex -
				    le16_to_cpu(p->header.nextindex) +
				    XTENTRYSTART;
				newpage = 1;
			}
		}
	} else {
		/* if insert into middle, shift right remaining entries */
		if (newindex < nextindex)
			memmove(&p->xad[newindex + 1], &p->xad[newindex],
				(nextindex - newindex) << L2XTSLOTSIZE);

		/* insert the entry */
		xad = &p->xad[newindex];
		*xad = *nxad;
		xad->flag = xflag & ~XAD_NOTRECORDED;

		/* advance next available entry index. */
		p->header.nextindex =
		    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
	}

	/*
	 * does nXAD force 3-way split ?
	 *
	 *          |---nXAD--->|
	 * --|----------XAD-------------|--
	 *   |-lXAD-|           |-rXAD -|
	 */
	if (nxoff + nxlen == xoff + xlen)
		goto out;

	/* reorient nXAD as XAD for further split XAD into (nXAD, rXAD) */
	if (newpage) {
		/* close out old page */
		if (!test_cflag(COMMIT_Nolink, ip)) {
			xtlck->lwm.offset = (xtlck->lwm.offset) ?
			    min(index0, (int)xtlck->lwm.offset) : index0;
			xtlck->lwm.length =
			    le16_to_cpu(p->header.nextindex) -
			    xtlck->lwm.offset;
		}

		bn = le64_to_cpu(p->header.next);
		XT_PUTPAGE(mp);

		/* get new right page */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		BT_MARK_DIRTY(mp, ip);
		if (!test_cflag(COMMIT_Nolink, ip)) {
			tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
			xtlck = (struct xtlock *) & tlck->lock;
		}

		index0 = index = newindex;
	} else
		index++;

	newindex = index + 1;
	nextindex = le16_to_cpu(p->header.nextindex);
	xlen = xlen - (nxoff - xoff);
	xoff = nxoff;
	xaddr = nxaddr;

	/* recompute split pages */
	if (nextindex == le16_to_cpu(p->header.maxentry)) {
		XT_PUTPAGE(mp);

		if ((rc = xtSearch(ip, nxoff, NULL, &cmp, &btstack, XT_INSERT)))
			return rc;

		/* retrieve search result */
		XT_GETSEARCH(ip, btstack.top, bn, mp, p, index0);

		if (cmp != 0) {
			XT_PUTPAGE(mp);
			jfs_error(ip->i_sb, "xtUpdate: xtSearch failed");
			return -EIO;
		}

		if (index0 != index) {
			XT_PUTPAGE(mp);
			jfs_error(ip->i_sb,
				  "xtUpdate: unexpected value of index");
			return -EIO;
		}
	}

	/*
	 * split XAD into (nXAD, rXAD)
	 *
	 *          ---nXAD---|
	 * --|----------XAD----------|--
	 *                    |-rXAD-|
	 */
      updateLeft:		/* (nxoff == xoff) && (nxlen < xlen) */
	/* update old XAD with nXAD:recorded */
	xad = &p->xad[index];
	*xad = *nxad;
	xad->flag = xflag & ~XAD_NOTRECORDED;

	/* insert rXAD:not_recorded */
	xoff = xoff + nxlen;
	xlen = xlen - nxlen;
	xaddr = xaddr + nxlen;
	if (nextindex == le16_to_cpu(p->header.maxentry)) {
/*
printf("xtUpdate.updateLeft.split p:0x%p\n", p);
*/
		/* xtSpliUp() unpins leaf pages */
		split.mp = mp;
		split.index = newindex;
		split.flag = xflag;
		split.off = xoff;
		split.len = xlen;
		split.addr = xaddr;
		split.pxdlist = NULL;
		if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
			return rc;

		/* get back old page */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		/*
		 * if leaf root has been split, original root has been
		 * copied to new child page, i.e., original entry now
		 * resides on the new child page;
		 */
		if (p->header.flag & BT_INTERNAL) {
			ASSERT(p->header.nextindex ==
			       cpu_to_le16(XTENTRYSTART + 1));
			xad = &p->xad[XTENTRYSTART];
			bn = addressXAD(xad);
			XT_PUTPAGE(mp);

			/* get new child page */
			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
			if (rc)
				return rc;

			BT_MARK_DIRTY(mp, ip);
			if (!test_cflag(COMMIT_Nolink, ip)) {
				tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
				xtlck = (struct xtlock *) & tlck->lock;
			}
		}
	} else {
		/* if insert into middle, shift right remaining entries */
		if (newindex < nextindex)
			memmove(&p->xad[newindex + 1], &p->xad[newindex],
				(nextindex - newindex) << L2XTSLOTSIZE);

		/* insert the entry */
		xad = &p->xad[newindex];
		XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);

		/* advance next available entry index. */
		p->header.nextindex =
		    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
	}

      out:
	if (!test_cflag(COMMIT_Nolink, ip)) {
		xtlck->lwm.offset = (xtlck->lwm.offset) ?
		    min(index0, (int)xtlck->lwm.offset) : index0;
		xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
		    xtlck->lwm.offset;
	}

	/* unpin the leaf page */
	XT_PUTPAGE(mp);

	return rc;
}


/*
 *      xtAppend()
 *
 * function: grow in append mode from contiguous region specified ;
 *
 * parameter:
 *      tid             - transaction id;
 *      ip              - file object;
 *      xflag           - extent flag:
 *      xoff            - extent offset;
 *      maxblocks       - max extent length;
 *      xlen            - extent length (in/out);
 *      xaddrp          - extent address pointer (in/out):
 *      flag            -
 *
 * return:
 */
int xtAppend(tid_t tid,		/* transaction id */
	     struct inode *ip, int xflag, s64 xoff, s32 maxblocks,	
	     s32 * xlenp,	/* (in/out) */
	     s64 * xaddrp,	/* (in/out) */
	     int flag)
{
	int rc = 0;
	struct metapage *mp;	/* meta-page buffer */
	xtpage_t *p;		/* base B+-tree index page */
	s64 bn, xaddr;
	int index, nextindex;
	struct btstack btstack;	/* traverse stack */
	struct xtsplit split;	/* split information */
	xad_t *xad;
	int cmp;
	struct tlock *tlck;
	struct xtlock *xtlck;
	int nsplit, nblocks, xlen;
	struct pxdlist pxdlist;
	pxd_t *pxd;
	s64 next;

	xaddr = *xaddrp;
	xlen = *xlenp;
	jfs_info("xtAppend: xoff:0x%lx maxblocks:%d xlen:%d xaddr:0x%lx",
		 (ulong) xoff, maxblocks, xlen, (ulong) xaddr);

	/*
	 *      search for the entry location at which to insert:
	 *
	 * xtFastSearch() and xtSearch() both returns (leaf page
	 * pinned, index at which to insert).
	 * n.b. xtSearch() may return index of maxentry of
	 * the full page.
	 */
	if ((rc = xtSearch(ip, xoff, &next, &cmp, &btstack, XT_INSERT)))
		return rc;

	/* retrieve search result */
	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

	if (cmp == 0) {
		rc = -EEXIST;
		goto out;
	}

	if (next)
		xlen = min(xlen, (int)(next - xoff));
//insert:
	/*
	 *      insert entry for new extent
	 */
	xflag |= XAD_NEW;

	/*
	 *      if the leaf page is full, split the page and
	 *      propagate up the router entry for the new page from split
	 *
	 * The xtSplitUp() will insert the entry and unpin the leaf page.
	 */
	nextindex = le16_to_cpu(p->header.nextindex);
	if (nextindex < le16_to_cpu(p->header.maxentry))
		goto insertLeaf;

	/*
	 * allocate new index blocks to cover index page split(s)
	 */
	nsplit = btstack.nsplit;
	split.pxdlist = &pxdlist;
	pxdlist.maxnpxd = pxdlist.npxd = 0;
	pxd = &pxdlist.pxd[0];
	nblocks = JFS_SBI(ip->i_sb)->nbperpage;
	for (; nsplit > 0; nsplit--, pxd++, xaddr += nblocks, maxblocks -= nblocks) {	
		if ((rc = dbAllocBottomUp(ip, xaddr, (s64) nblocks)) == 0) {
			PXDaddress(pxd, xaddr);
			PXDlength(pxd, nblocks);

			pxdlist.maxnpxd++;

			continue;
		}

		/* undo allocation */

		goto out;
	}

	xlen = min(xlen, maxblocks);	

	/*
	 * allocate data extent requested
	 */
	if ((rc = dbAllocBottomUp(ip, xaddr, (s64) xlen)))
		goto out;

	split.mp = mp;
	split.index = index;
	split.flag = xflag;
	split.off = xoff;
	split.len = xlen;
	split.addr = xaddr;
	if ((rc = xtSplitUp(tid, ip, &split, &btstack))) {
		/* undo data extent allocation */
		dbFree(ip, *xaddrp, (s64) * xlenp);

		return rc;
	}

	*xaddrp = xaddr;
	*xlenp = xlen;
	return 0;

	/*
	 *      insert the new entry into the leaf page
	 */
      insertLeaf:
	/*
	 * allocate data extent requested
	 */
	if ((rc = dbAllocBottomUp(ip, xaddr, (s64) xlen)))
		goto out;

	BT_MARK_DIRTY(mp, ip);
	/*
	 * acquire a transaction lock on the leaf page;
	 *
	 * action: xad insertion/extension;
	 */
	tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
	xtlck = (struct xtlock *) & tlck->lock;

	/* insert the new entry: mark the entry NEW */
	xad = &p->xad[index];
	XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);

	/* advance next available entry index */
	p->header.nextindex =
	    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);

	xtlck->lwm.offset =
	    (xtlck->lwm.offset) ? min(index,(int) xtlck->lwm.offset) : index;
	xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
	    xtlck->lwm.offset;

	*xaddrp = xaddr;
	*xlenp = xlen;

      out:
	/* unpin the leaf page */
	XT_PUTPAGE(mp);

	return rc;
}
#ifdef _STILL_TO_PORT

/* - TBD for defragmentaion/reorganization -
 *
 *      xtDelete()
 *
 * function:
 *      delete the entry with the specified key.
 *
 *      N.B.: whole extent of the entry is assumed to be deleted.
 *
 * parameter:
 *
 * return:
 *       ENOENT: if the entry is not found.
 *
 * exception:
 */
int xtDelete(tid_t tid, struct inode *ip, s64 xoff, s32 xlen, int flag)
{
	int rc = 0;
	struct btstack btstack;
	int cmp;
	s64 bn;
	struct metapage *mp;
	xtpage_t *p;
	int index, nextindex;
	struct tlock *tlck;
	struct xtlock *xtlck;

	/*
	 * find the matching entry; xtSearch() pins the page
	 */
	if ((rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0)))
		return rc;

	XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
	if (cmp) {
		/* unpin the leaf page */
		XT_PUTPAGE(mp);
		return -ENOENT;
	}

	/*
	 * delete the entry from the leaf page
	 */
	nextindex = le16_to_cpu(p->header.nextindex);
	p->header.nextindex =
	    cpu_to_le16(le16_to_cpu(p->header.nextindex) - 1);

	/*
	 * if the leaf page bocome empty, free the page
	 */
	if (p->header.nextindex == cpu_to_le16(XTENTRYSTART))
		return (xtDeleteUp(tid, ip, mp, p, &btstack));

	BT_MARK_DIRTY(mp, ip);
	/*
	 * acquire a transaction lock on the leaf page;
	 *
	 * action:xad deletion;
	 */
	tlck = txLock(tid, ip, mp, tlckXTREE);
	xtlck = (struct xtlock *) & tlck->lock;
	xtlck->lwm.offset =
	    (xtlck->lwm.offset) ? min(index, xtlck->lwm.offset) : index;

	/* if delete from middle, shift left/compact the remaining entries */
	if (index < nextindex - 1)
		memmove(&p->xad[index], &p->xad[index + 1],
			(nextindex - index - 1) * sizeof(xad_t));

	XT_PUTPAGE(mp);

	return 0;
}


/* - TBD for defragmentaion/reorganization -
 *
 *      xtDeleteUp()
 *
 * function:
 *      free empty pages as propagating deletion up the tree
 *
 * parameter:
 *
 * return:
 */
static int
xtDeleteUp(tid_t tid, struct inode *ip,
	   struct metapage * fmp, xtpage_t * fp, struct btstack * btstack)
{
	int rc = 0;
	struct metapage *mp;
	xtpage_t *p;
	int index, nextindex;
	s64 xaddr;
	int xlen;
	struct btframe *parent;
	struct tlock *tlck;
	struct xtlock *xtlck;

	/*
	 * keep root leaf page which has become empty
	 */
	if (fp->header.flag & BT_ROOT) {
		/* keep the root page */
		fp->header.flag &= ~BT_INTERNAL;
		fp->header.flag |= BT_LEAF;
		fp->header.nextindex = cpu_to_le16(XTENTRYSTART);

		/* XT_PUTPAGE(fmp); */

		return 0;
	}

	/*
	 * free non-root leaf page
	 */
	if ((rc = xtRelink(tid, ip, fp))) {
		XT_PUTPAGE(fmp);
		return rc;
	}

	xaddr = addressPXD(&fp->header.self);
	xlen = lengthPXD(&fp->header.self);
	/* free the page extent */
	dbFree(ip, xaddr, (s64) xlen);

	/* free the buffer page */
	discard_metapage(fmp);

	/*
	 * propagate page deletion up the index tree
	 *
	 * If the delete from the parent page makes it empty,
	 * continue all the way up the tree.
	 * stop if the root page is reached (which is never deleted) or
	 * if the entry deletion does not empty the page.
	 */
	while ((parent = BT_POP(btstack)) != NULL) {
		/* get/pin the parent page <sp> */
		XT_GETPAGE(ip, parent->bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		index = parent->index;

		/* delete the entry for the freed child page from parent.
		 */
		nextindex = le16_to_cpu(p->header.nextindex);

		/*
		 * the parent has the single entry being deleted:
		 * free the parent page which has become empty.
		 */
		if (nextindex == 1) {
			if (p->header.flag & BT_ROOT) {
				/* keep the root page */
				p->header.flag &= ~BT_INTERNAL;
				p->header.flag |= BT_LEAF;
				p->header.nextindex =
				    cpu_to_le16(XTENTRYSTART);

				/* XT_PUTPAGE(mp); */

				break;
			} else {
				/* free the parent page */
				if ((rc = xtRelink(tid, ip, p)))
					return rc;

				xaddr = addressPXD(&p->header.self);
				/* free the page extent */
				dbFree(ip, xaddr,
				       (s64) JFS_SBI(ip->i_sb)->nbperpage);

				/* unpin/free the buffer page */
				discard_metapage(mp);

				/* propagate up */
				continue;
			}
		}
		/*
		 * the parent has other entries remaining:
		 * delete the router entry from the parent page.
		 */
		else {
			BT_MARK_DIRTY(mp, ip);
			/*
			 * acquire a transaction lock on the leaf page;
			 *
			 * action:xad deletion;
			 */
			tlck = txLock(tid, ip, mp, tlckXTREE);
			xtlck = (struct xtlock *) & tlck->lock;
			xtlck->lwm.offset =
			    (xtlck->lwm.offset) ? min(index,
						      xtlck->lwm.
						      offset) : index;

			/* if delete from middle,
			 * shift left/compact the remaining entries in the page
			 */
			if (index < nextindex - 1)
				memmove(&p->xad[index], &p->xad[index + 1],
					(nextindex - index -
					 1) << L2XTSLOTSIZE);

			p->header.nextindex =
			    cpu_to_le16(le16_to_cpu(p->header.nextindex) -
					1);
			jfs_info("xtDeleteUp(entry): 0x%lx[%d]",
				 (ulong) parent->bn, index);
		}

		/* unpin the parent page */
		XT_PUTPAGE(mp);

		/* exit propagation up */
		break;
	}

	return 0;
}


/*
 * NAME:        xtRelocate()
 *
 * FUNCTION:    relocate xtpage or data extent of regular file;
 *              This function is mainly used by defragfs utility.
 *
 * NOTE:        This routine does not have the logic to handle
 *              uncommitted allocated extent. The caller should call
 *              txCommit() to commit all the allocation before call
 *              this routine.
 */
int
xtRelocate(tid_t tid, struct inode * ip, xad_t * oxad,	/* old XAD */
	   s64 nxaddr,		/* new xaddr */
	   int xtype)
{				/* extent type: XTPAGE or DATAEXT */
	int rc = 0;
	struct tblock *tblk;
	struct tlock *tlck;
	struct xtlock *xtlck;
	struct metapage *mp, *pmp, *lmp, *rmp;	/* meta-page buffer */
	xtpage_t *p, *pp, *rp, *lp;	/* base B+-tree index page */
	xad_t *xad;
	pxd_t *pxd;
	s64 xoff, xsize;
	int xlen;
	s64 oxaddr, sxaddr, dxaddr, nextbn, prevbn;
	cbuf_t *cp;
	s64 offset, nbytes, nbrd, pno;
	int nb, npages, nblks;
	s64 bn;
	int cmp;
	int index;
	struct pxd_lock *pxdlock;
	struct btstack btstack;	/* traverse stack */

	xtype = xtype & EXTENT_TYPE;

	xoff = offsetXAD(oxad);
	oxaddr = addressXAD(oxad);
	xlen = lengthXAD(oxad);

	/* validate extent offset */
	offset = xoff << JFS_SBI(ip->i_sb)->l2bsize;
	if (offset >= ip->i_size)
		return -ESTALE;	/* stale extent */

	jfs_info("xtRelocate: xtype:%d xoff:0x%lx xlen:0x%x xaddr:0x%lx:0x%lx",
		 xtype, (ulong) xoff, xlen, (ulong) oxaddr, (ulong) nxaddr);

	/*
	 *      1. get and validate the parent xtpage/xad entry
	 *      covering the source extent to be relocated;
	 */
	if (xtype == DATAEXT) {
		/* search in leaf entry */
		rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0);
		if (rc)
			return rc;

		/* retrieve search result */
		XT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);

		if (cmp) {
			XT_PUTPAGE(pmp);
			return -ESTALE;
		}

		/* validate for exact match with a single entry */
		xad = &pp->xad[index];
		if (addressXAD(xad) != oxaddr || lengthXAD(xad) != xlen) {
			XT_PUTPAGE(pmp);
			return -ESTALE;
		}
	} else {		/* (xtype == XTPAGE) */

		/* search in internal entry */
		rc = xtSearchNode(ip, oxad, &cmp, &btstack, 0);
		if (rc)
			return rc;

		/* retrieve search result */
		XT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);

		if (cmp) {
			XT_PUTPAGE(pmp);
			return -ESTALE;
		}

		/* xtSearchNode() validated for exact match with a single entry
		 */
		xad = &pp->xad[index];
	}
	jfs_info("xtRelocate: parent xad entry validated.");

	/*
	 *      2. relocate the extent
	 */
	if (xtype == DATAEXT) {
		/* if the extent is allocated-but-not-recorded
		 * there is no real data to be moved in this extent,
		 */
		if (xad->flag & XAD_NOTRECORDED)
			goto out;
		else
			/* release xtpage for cmRead()/xtLookup() */
			XT_PUTPAGE(pmp);

		/*
		 *      cmRelocate()
		 *
		 * copy target data pages to be relocated;
		 *
		 * data extent must start at page boundary and
		 * multiple of page size (except the last data extent);
		 * read in each page of the source data extent into cbuf,
		 * update the cbuf extent descriptor of the page to be
		 * homeward bound to new dst data extent
		 * copy the data from the old extent to new extent.
		 * copy is essential for compressed files to avoid problems
		 * that can arise if there was a change in compression
		 * algorithms.
		 * it is a good strategy because it may disrupt cache
		 * policy to keep the pages in memory afterwards.
		 */
		offset = xoff << JFS_SBI(ip->i_sb)->l2bsize;
		assert((offset & CM_OFFSET) == 0);
		nbytes = xlen << JFS_SBI(ip->i_sb)->l2bsize;
		pno = offset >> CM_L2BSIZE;
		npages = (nbytes + (CM_BSIZE - 1)) >> CM_L2BSIZE;
/*
                npages = ((offset + nbytes - 1) >> CM_L2BSIZE) -
                         (offset >> CM_L2BSIZE) + 1;
*/
		sxaddr = oxaddr;
		dxaddr = nxaddr;

		/* process the request one cache buffer at a time */
		for (nbrd = 0; nbrd < nbytes; nbrd += nb,
		     offset += nb, pno++, npages--) {
			/* compute page size */
			nb = min(nbytes - nbrd, CM_BSIZE);

			/* get the cache buffer of the page */
			if (rc = cmRead(ip, offset, npages, &cp))
				break;

			assert(addressPXD(&cp->cm_pxd) == sxaddr);
			assert(!cp->cm_modified);

			/* bind buffer with the new extent address */
			nblks = nb >> JFS_IP(ip->i_sb)->l2bsize;
			cmSetXD(ip, cp, pno, dxaddr, nblks);

			/* release the cbuf, mark it as modified */
			cmPut(cp, TRUE);

			dxaddr += nblks;
			sxaddr += nblks;
		}

		/* get back parent page */
		if ((rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0)))
			return rc;

		XT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);
		jfs_info("xtRelocate: target data extent relocated.");
	} else {		/* (xtype  == XTPAGE) */

		/*
		 * read in the target xtpage from the source extent;
		 */
		XT_GETPAGE(ip, oxaddr, mp, PSIZE, p, rc);
		if (rc) {
			XT_PUTPAGE(pmp);
			return rc;
		}

		/*
		 * read in sibling pages if any to update sibling pointers;
		 */
		rmp = NULL;
		if (p->header.next) {
			nextbn = le64_to_cpu(p->header.next);
			XT_GETPAGE(ip, nextbn, rmp, PSIZE, rp, rc);
			if (rc) {
				XT_PUTPAGE(pmp);
				XT_PUTPAGE(mp);
				return (rc);
			}
		}

		lmp = NULL;
		if (p->header.prev) {
			prevbn = le64_to_cpu(p->header.prev);
			XT_GETPAGE(ip, prevbn, lmp, PSIZE, lp, rc);
			if (rc) {
				XT_PUTPAGE(pmp);
				XT_PUTPAGE(mp);
				if (rmp)
					XT_PUTPAGE(rmp);
				return (rc);
			}
		}

		/* at this point, all xtpages to be updated are in memory */

		/*
		 * update sibling pointers of sibling xtpages if any;
		 */
		if (lmp) {
			BT_MARK_DIRTY(lmp, ip);
			tlck =
			    txLock(tid, ip, lmp, tlckXTREE | tlckRELINK);
			lp->header.next = cpu_to_le64(nxaddr);
			XT_PUTPAGE(lmp);
		}

		if (rmp) {
			BT_MARK_DIRTY(rmp, ip);
			tlck =
			    txLock(tid, ip, rmp, tlckXTREE | tlckRELINK);
			rp->header.prev = cpu_to_le64(nxaddr);
			XT_PUTPAGE(rmp);
		}

		/*
		 * update the target xtpage to be relocated
		 *
		 * update the self address of the target page
		 * and write to destination extent;
		 * redo image covers the whole xtpage since it is new page
		 * to the destination extent;
		 * update of bmap for the free of source extent
		 * of the target xtpage itself:
		 * update of bmap for the allocation of destination extent
		 * of the target xtpage itself:
		 * update of bmap for the extents covered by xad entries in
		 * the target xtpage is not necessary since they are not
		 * updated;
		 * if not committed before this relocation,
		 * target page may contain XAD_NEW entries which must
		 * be scanned for bmap update (logredo() always
		 * scan xtpage REDOPAGE image for bmap update);
		 * if committed before this relocation (tlckRELOCATE),
		 * scan may be skipped by commit() and logredo();
		 */
		BT_MARK_DIRTY(mp, ip);
		/* tlckNEW init  xtlck->lwm.offset = XTENTRYSTART; */
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckNEW);
		xtlck = (struct xtlock *) & tlck->lock;

		/* update the self address in the xtpage header */
		pxd = &p->header.self;
		PXDaddress(pxd, nxaddr);

		/* linelock for the after image of the whole page */
		xtlck->lwm.length =
		    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;

		/* update the buffer extent descriptor of target xtpage */
		xsize = xlen << JFS_SBI(ip->i_sb)->l2bsize;
		bmSetXD(mp, nxaddr, xsize);

		/* unpin the target page to new homeward bound */
		XT_PUTPAGE(mp);
		jfs_info("xtRelocate: target xtpage relocated.");
	}

	/*
	 *      3. acquire maplock for the source extent to be freed;
	 *
	 * acquire a maplock saving the src relocated extent address;
	 * to free of the extent at commit time;
	 */
      out:
	/* if DATAEXT relocation, write a LOG_UPDATEMAP record for
	 * free PXD of the source data extent (logredo() will update
	 * bmap for free of source data extent), and update bmap for
	 * free of the source data extent;
	 */
	if (xtype == DATAEXT)
		tlck = txMaplock(tid, ip, tlckMAP);
	/* if XTPAGE relocation, write a LOG_NOREDOPAGE record
	 * for the source xtpage (logredo() will init NoRedoPage
	 * filter and will also update bmap for free of the source
	 * xtpage), and update bmap for free of the source xtpage;
	 * N.B. We use tlckMAP instead of tlkcXTREE because there
	 *      is no buffer associated with this lock since the buffer
	 *      has been redirected to the target location.
	 */
	else			/* (xtype  == XTPAGE) */
		tlck = txMaplock(tid, ip, tlckMAP | tlckRELOCATE);

	pxdlock = (struct pxd_lock *) & tlck->lock;
	pxdlock->flag = mlckFREEPXD;
	PXDaddress(&pxdlock->pxd, oxaddr);
	PXDlength(&pxdlock->pxd, xlen);
	pxdlock->index = 1;

	/*
	 *      4. update the parent xad entry for relocation;
	 *
	 * acquire tlck for the parent entry with XAD_NEW as entry
	 * update which will write LOG_REDOPAGE and update bmap for
	 * allocation of XAD_NEW destination extent;
	 */
	jfs_info("xtRelocate: update parent xad entry.");
	BT_MARK_DIRTY(pmp, ip);
	tlck = txLock(tid, ip, pmp, tlckXTREE | tlckGROW);
	xtlck = (struct xtlock *) & tlck->lock;

	/* update the XAD with the new destination extent; */
	xad = &pp->xad[index];
	xad->flag |= XAD_NEW;
	XADaddress(xad, nxaddr);

	xtlck->lwm.offset = min(index, xtlck->lwm.offset);
	xtlck->lwm.length = le16_to_cpu(pp->header.nextindex) -
	    xtlck->lwm.offset;

	/* unpin the parent xtpage */
	XT_PUTPAGE(pmp);

	return rc;
}


/*
 *      xtSearchNode()
 *
 * function:    search for the internal xad entry covering specified extent.
 *              This function is mainly used by defragfs utility.
 *
 * parameters:
 *      ip      - file object;
 *      xad     - extent to find;
 *      cmpp    - comparison result:
 *      btstack - traverse stack;
 *      flag    - search process flag;
 *
 * returns:
 *      btstack contains (bn, index) of search path traversed to the entry.
 *      *cmpp is set to result of comparison with the entry returned.
 *      the page containing the entry is pinned at exit.
 */
static int xtSearchNode(struct inode *ip, xad_t * xad,	/* required XAD entry */
			int *cmpp, struct btstack * btstack, int flag)
{
	int rc = 0;
	s64 xoff, xaddr;
	int xlen;
	int cmp = 1;		/* init for empty page */
	s64 bn;			/* block number */
	struct metapage *mp;	/* meta-page buffer */
	xtpage_t *p;		/* page */
	int base, index, lim;
	struct btframe *btsp;
	s64 t64;

	BT_CLR(btstack);

	xoff = offsetXAD(xad);
	xlen = lengthXAD(xad);
	xaddr = addressXAD(xad);

	/*
	 *      search down tree from root:
	 *
	 * between two consecutive entries of <Ki, Pi> and <Kj, Pj> of
	 * internal page, child page Pi contains entry with k, Ki <= K < Kj.
	 *
	 * if entry with search key K is not found
	 * internal page search find the entry with largest key Ki
	 * less than K which point to the child page to search;
	 * leaf page search find the entry with smallest key Kj
	 * greater than K so that the returned index is the position of
	 * the entry to be shifted right for insertion of new entry.
	 * for empty tree, search key is greater than any key of the tree.
	 *
	 * by convention, root bn = 0.
	 */
	for (bn = 0;;) {
		/* get/pin the page to search */
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;
		if (p->header.flag & BT_LEAF) {
			XT_PUTPAGE(mp);
			return -ESTALE;
		}

		lim = le16_to_cpu(p->header.nextindex) - XTENTRYSTART;

		/*
		 * binary search with search key K on the current page
		 */
		for (base = XTENTRYSTART; lim; lim >>= 1) {
			index = base + (lim >> 1);

			XT_CMP(cmp, xoff, &p->xad[index], t64);
			if (cmp == 0) {
				/*
				 *      search hit
				 *
				 * verify for exact match;
				 */
				if (xaddr == addressXAD(&p->xad[index]) &&
				    xoff == offsetXAD(&p->xad[index])) {
					*cmpp = cmp;

					/* save search result */
					btsp = btstack->top;
					btsp->bn = bn;
					btsp->index = index;
					btsp->mp = mp;

					return 0;
				}

				/* descend/search its child page */
				goto next;
			}

			if (cmp > 0) {
				base = index + 1;
				--lim;
			}
		}

		/*
		 *      search miss - non-leaf page:
		 *
		 * base is the smallest index with key (Kj) greater than
		 * search key (K) and may be zero or maxentry index.
		 * if base is non-zero, decrement base by one to get the parent
		 * entry of the child page to search.
		 */
		index = base ? base - 1 : base;

		/*
		 * go down to child page
		 */
	      next:
		/* get the child page block number */
		bn = addressXAD(&p->xad[index]);

		/* unpin the parent page */
		XT_PUTPAGE(mp);
	}
}


/*
 *      xtRelink()
 *
 * function:
 *      link around a freed page.
 *
 * Parameter:
 *      int           tid,
 *      struct inode    *ip,
 *      xtpage_t        *p)
 *
 * returns:
 */
static int xtRelink(tid_t tid, struct inode *ip, xtpage_t * p)
{
	int rc = 0;
	struct metapage *mp;
	s64 nextbn, prevbn;
	struct tlock *tlck;

	nextbn = le64_to_cpu(p->header.next);
	prevbn = le64_to_cpu(p->header.prev);

	/* update prev pointer of the next page */
	if (nextbn != 0) {
		XT_GETPAGE(ip, nextbn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		/*
		 * acquire a transaction lock on the page;
		 *
		 * action: update prev pointer;
		 */
		BT_MARK_DIRTY(mp, ip);
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckRELINK);

		/* the page may already have been tlock'd */

		p->header.prev = cpu_to_le64(prevbn);

		XT_PUTPAGE(mp);
	}

	/* update next pointer of the previous page */
	if (prevbn != 0) {
		XT_GETPAGE(ip, prevbn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		/*
		 * acquire a transaction lock on the page;
		 *
		 * action: update next pointer;
		 */
		BT_MARK_DIRTY(mp, ip);
		tlck = txLock(tid, ip, mp, tlckXTREE | tlckRELINK);

		/* the page may already have been tlock'd */

		p->header.next = le64_to_cpu(nextbn);

		XT_PUTPAGE(mp);
	}

	return 0;
}
#endif				/*  _STILL_TO_PORT */


/*
 *      xtInitRoot()
 *
 * initialize file root (inline in inode)
 */
void xtInitRoot(tid_t tid, struct inode *ip)
{
	xtpage_t *p;

	/*
	 * acquire a transaction lock on the root
	 *
	 * action:
	 */
	txLock(tid, ip, (struct metapage *) &JFS_IP(ip)->bxflag,
		      tlckXTREE | tlckNEW);
	p = &JFS_IP(ip)->i_xtroot;

	p->header.flag = DXD_INDEX | BT_ROOT | BT_LEAF;
	p->header.nextindex = cpu_to_le16(XTENTRYSTART);

	if (S_ISDIR(ip->i_mode))
		p->header.maxentry = cpu_to_le16(XTROOTINITSLOT_DIR);
	else {
		p->header.maxentry = cpu_to_le16(XTROOTINITSLOT);
		ip->i_size = 0;
	}


	return;
}


/*
 * We can run into a deadlock truncating a file with a large number of
 * xtree pages (large fragmented file).  A robust fix would entail a
 * reservation system where we would reserve a number of metadata pages
 * and tlocks which we would be guaranteed without a deadlock.  Without
 * this, a partial fix is to limit number of metadata pages we will lock
 * in a single transaction.  Currently we will truncate the file so that
 * no more than 50 leaf pages will be locked.  The caller of xtTruncate
 * will be responsible for ensuring that the current transaction gets
 * committed, and that subsequent transactions are created to truncate
 * the file further if needed.
 */
#define MAX_TRUNCATE_LEAVES 50

/*
 *      xtTruncate()
 *
 * function:
 *      traverse for truncation logging backward bottom up;
 *      terminate at the last extent entry at the current subtree
 *      root page covering new down size.
 *      truncation may occur within the last extent entry.
 *
 * parameter:
 *      int           tid,
 *      struct inode    *ip,
 *      s64           newsize,
 *      int           type)   {PWMAP, PMAP, WMAP; DELETE, TRUNCATE}
 *
 * return:
 *
 * note:
 *      PWMAP:
 *       1. truncate (non-COMMIT_NOLINK file)
 *          by jfs_truncate() or jfs_open(O_TRUNC):
 *          xtree is updated;
 *	 2. truncate index table of directory when last entry removed
 *       map update via tlock at commit time;
 *      PMAP:
 *	 Call xtTruncate_pmap instead
 *      WMAP:
 *       1. remove (free zero link count) on last reference release
 *          (pmap has been freed at commit zero link count);
 *       2. truncate (COMMIT_NOLINK file, i.e., tmp file):
 *          xtree is updated;
 *       map update directly at truncation time;
 *
 *      if (DELETE)
 *              no LOG_NOREDOPAGE is required (NOREDOFILE is sufficient);
 *      else if (TRUNCATE)
 *              must write LOG_NOREDOPAGE for deleted index page;
 *
 * pages may already have been tlocked by anonymous transactions
 * during file growth (i.e., write) before truncation;
 *
 * except last truncated entry, deleted entries remains as is
 * in the page (nextindex is updated) for other use
 * (e.g., log/update allocation map): this avoid copying the page
 * info but delay free of pages;
 *
 */
s64 xtTruncate(tid_t tid, struct inode *ip, s64 newsize, int flag)
{
	int rc = 0;
	s64 teof;
	struct metapage *mp;
	xtpage_t *p;
	s64 bn;
	int index, nextindex;
	xad_t *xad;
	s64 xoff, xaddr;
	int xlen, len, freexlen;
	struct btstack btstack;
	struct btframe *parent;
	struct tblock *tblk = NULL;
	struct tlock *tlck = NULL;
	struct xtlock *xtlck = NULL;
	struct xdlistlock xadlock;	/* maplock for COMMIT_WMAP */
	struct pxd_lock *pxdlock;		/* maplock for COMMIT_WMAP */
	s64 nfreed;
	int freed, log;
	int locked_leaves = 0;

	/* save object truncation type */
	if (tid) {
		tblk = tid_to_tblock(tid);
		tblk->xflag |= flag;
	}

	nfreed = 0;

	flag &= COMMIT_MAP;
	assert(flag != COMMIT_PMAP);

	if (flag == COMMIT_PWMAP)
		log = 1;
	else {
		log = 0;
		xadlock.flag = mlckFREEXADLIST;
		xadlock.index = 1;
	}

	/*
	 * if the newsize is not an integral number of pages,
	 * the file between newsize and next page boundary will
	 * be cleared.
	 * if truncating into a file hole, it will cause
	 * a full block to be allocated for the logical block.
	 */

	/*
	 * release page blocks of truncated region <teof, eof>
	 *
	 * free the data blocks from the leaf index blocks.
	 * delete the parent index entries corresponding to
	 * the freed child data/index blocks.
	 * free the index blocks themselves which aren't needed
	 * in new sized file.
	 *
	 * index blocks are updated only if the blocks are to be
	 * retained in the new sized file.
	 * if type is PMAP, the data and index pages are NOT
	 * freed, and the data and index blocks are NOT freed
	 * from  working map.
	 * (this will allow continued access of data/index of
	 * temporary file (zerolink count file truncated to zero-length)).
	 */
	teof = (newsize + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
	    JFS_SBI(ip->i_sb)->l2bsize;

	/* clear stack */
	BT_CLR(&btstack);

	/*
	 * start with root
	 *
	 * root resides in the inode
	 */
	bn = 0;

	/*
	 * first access of each page:
	 */
      getPage:
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	/* process entries backward from last index */
	index = le16_to_cpu(p->header.nextindex) - 1;

	if (p->header.flag & BT_INTERNAL)
		goto getChild;

	/*
	 *      leaf page
	 */

	/* Since this is the rightmost leaf, and we may have already freed
	 * a page that was formerly to the right, let's make sure that the
	 * next pointer is zero.
	 */
	if (p->header.next) {
		if (log)
			/*
			 * Make sure this change to the header is logged.
			 * If we really truncate this leaf, the flag
			 * will be changed to tlckTRUNCATE
			 */
			tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
		BT_MARK_DIRTY(mp, ip);
		p->header.next = 0;
	}

	freed = 0;

	/* does region covered by leaf page precede Teof ? */
	xad = &p->xad[index];
	xoff = offsetXAD(xad);
	xlen = lengthXAD(xad);
	if (teof >= xoff + xlen) {
		XT_PUTPAGE(mp);
		goto getParent;
	}

	/* (re)acquire tlock of the leaf page */
	if (log) {
		if (++locked_leaves > MAX_TRUNCATE_LEAVES) {
			/*
			 * We need to limit the size of the transaction
			 * to avoid exhausting pagecache & tlocks
			 */
			XT_PUTPAGE(mp);
			newsize = (xoff + xlen) << JFS_SBI(ip->i_sb)->l2bsize;
			goto getParent;
		}
		tlck = txLock(tid, ip, mp, tlckXTREE);
		tlck->type = tlckXTREE | tlckTRUNCATE;
		xtlck = (struct xtlock *) & tlck->lock;
		xtlck->hwm.offset = le16_to_cpu(p->header.nextindex) - 1;
	}
	BT_MARK_DIRTY(mp, ip);

	/*
	 * scan backward leaf page entries
	 */
	for (; index >= XTENTRYSTART; index--) {
		xad = &p->xad[index];
		xoff = offsetXAD(xad);
		xlen = lengthXAD(xad);
		xaddr = addressXAD(xad);

		/*
		 * The "data" for a directory is indexed by the block
		 * device's address space.  This metadata must be invalidated
		 * here
		 */
		if (S_ISDIR(ip->i_mode) && (teof == 0))
			invalidate_xad_metapages(ip, *xad);
		/*
		 * entry beyond eof: continue scan of current page
		 *          xad
		 * ---|---=======------->
		 *   eof
		 */
		if (teof < xoff) {
			nfreed += xlen;
			continue;
		}

		/*
		 * (xoff <= teof): last entry to be deleted from page;
		 * If other entries remain in page: keep and update the page.
		 */

		/*
		 * eof == entry_start: delete the entry
		 *           xad
		 * -------|=======------->
		 *       eof
		 *
		 */
		if (teof == xoff) {
			nfreed += xlen;

			if (index == XTENTRYSTART)
				break;

			nextindex = index;
		}
		/*
		 * eof within the entry: truncate the entry.
		 *          xad
		 * -------===|===------->
		 *          eof
		 */
		else if (teof < xoff + xlen) {
			/* update truncated entry */
			len = teof - xoff;
			freexlen = xlen - len;
			XADlength(xad, len);

			/* save pxd of truncated extent in tlck */
			xaddr += len;
			if (log) {	/* COMMIT_PWMAP */
				xtlck->lwm.offset = (xtlck->lwm.offset) ?
				    min(index, (int)xtlck->lwm.offset) : index;
				xtlck->lwm.length = index + 1 -
				    xtlck->lwm.offset;
				xtlck->twm.offset = index;
				pxdlock = (struct pxd_lock *) & xtlck->pxdlock;
				pxdlock->flag = mlckFREEPXD;
				PXDaddress(&pxdlock->pxd, xaddr);
				PXDlength(&pxdlock->pxd, freexlen);
			}
			/* free truncated extent */
			else {	/* COMMIT_WMAP */

				pxdlock = (struct pxd_lock *) & xadlock;
				pxdlock->flag = mlckFREEPXD;
				PXDaddress(&pxdlock->pxd, xaddr);
				PXDlength(&pxdlock->pxd, freexlen);
				txFreeMap(ip, pxdlock, NULL, COMMIT_WMAP);

				/* reset map lock */
				xadlock.flag = mlckFREEXADLIST;
			}

			/* current entry is new last entry; */
			nextindex = index + 1;

			nfreed += freexlen;
		}
		/*
		 * eof beyond the entry:
		 *          xad
		 * -------=======---|--->
		 *                 eof
		 */
		else {		/* (xoff + xlen < teof) */

			nextindex = index + 1;
		}

		if (nextindex < le16_to_cpu(p->header.nextindex)) {
			if (!log) {	/* COMMIT_WAMP */
				xadlock.xdlist = &p->xad[nextindex];
				xadlock.count =
				    le16_to_cpu(p->header.nextindex) -
				    nextindex;
				txFreeMap(ip, (struct maplock *) & xadlock,
					  NULL, COMMIT_WMAP);
			}
			p->header.nextindex = cpu_to_le16(nextindex);
		}

		XT_PUTPAGE(mp);

		/* assert(freed == 0); */
		goto getParent;
	}			/* end scan of leaf page entries */

	freed = 1;

	/*
	 * leaf page become empty: free the page if type != PMAP
	 */
	if (log) {		/* COMMIT_PWMAP */
		/* txCommit() with tlckFREE:
		 * free data extents covered by leaf [XTENTRYSTART:hwm);
		 * invalidate leaf if COMMIT_PWMAP;
		 * if (TRUNCATE), will write LOG_NOREDOPAGE;
		 */
		tlck->type = tlckXTREE | tlckFREE;
	} else {		/* COMMIT_WAMP */

		/* free data extents covered by leaf */
		xadlock.xdlist = &p->xad[XTENTRYSTART];
		xadlock.count =
		    le16_to_cpu(p->header.nextindex) - XTENTRYSTART;
		txFreeMap(ip, (struct maplock *) & xadlock, NULL, COMMIT_WMAP);
	}

	if (p->header.flag & BT_ROOT) {
		p->header.flag &= ~BT_INTERNAL;
		p->header.flag |= BT_LEAF;
		p->header.nextindex = cpu_to_le16(XTENTRYSTART);

		XT_PUTPAGE(mp);	/* debug */
		goto out;
	} else {
		if (log) {	/* COMMIT_PWMAP */
			/* page will be invalidated at tx completion
			 */
			XT_PUTPAGE(mp);
		} else {	/* COMMIT_WMAP */

			if (mp->lid)
				lid_to_tlock(mp->lid)->flag |= tlckFREELOCK;

			/* invalidate empty leaf page */
			discard_metapage(mp);
		}
	}

	/*
	 * the leaf page become empty: delete the parent entry
	 * for the leaf page if the parent page is to be kept
	 * in the new sized file.
	 */

	/*
	 * go back up to the parent page
	 */
      getParent:
	/* pop/restore parent entry for the current child page */
	if ((parent = BT_POP(&btstack)) == NULL)
		/* current page must have been root */
		goto out;

	/* get back the parent page */
	bn = parent->bn;
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	index = parent->index;

	/*
	 * child page was not empty:
	 */
	if (freed == 0) {
		/* has any entry deleted from parent ? */
		if (index < le16_to_cpu(p->header.nextindex) - 1) {
			/* (re)acquire tlock on the parent page */
			if (log) {	/* COMMIT_PWMAP */
				/* txCommit() with tlckTRUNCATE:
				 * free child extents covered by parent [);
				 */
				tlck = txLock(tid, ip, mp, tlckXTREE);
				xtlck = (struct xtlock *) & tlck->lock;
				if (!(tlck->type & tlckTRUNCATE)) {
					xtlck->hwm.offset =
					    le16_to_cpu(p->header.
							nextindex) - 1;
					tlck->type =
					    tlckXTREE | tlckTRUNCATE;
				}
			} else {	/* COMMIT_WMAP */

				/* free child extents covered by parent */
				xadlock.xdlist = &p->xad[index + 1];
				xadlock.count =
				    le16_to_cpu(p->header.nextindex) -
				    index - 1;
				txFreeMap(ip, (struct maplock *) & xadlock,
					  NULL, COMMIT_WMAP);
			}
			BT_MARK_DIRTY(mp, ip);

			p->header.nextindex = cpu_to_le16(index + 1);
		}
		XT_PUTPAGE(mp);
		goto getParent;
	}

	/*
	 * child page was empty:
	 */
	nfreed += lengthXAD(&p->xad[index]);

	/*
	 * During working map update, child page's tlock must be handled
	 * before parent's.  This is because the parent's tlock will cause
	 * the child's disk space to be marked available in the wmap, so
	 * it's important that the child page be released by that time.
	 *
	 * ToDo:  tlocks should be on doubly-linked list, so we can
	 * quickly remove it and add it to the end.
	 */

	/*
	 * Move parent page's tlock to the end of the tid's tlock list
	 */
	if (log && mp->lid && (tblk->last != mp->lid) &&
	    lid_to_tlock(mp->lid)->tid) {
		lid_t lid = mp->lid;
		struct tlock *prev;

		tlck = lid_to_tlock(lid);

		if (tblk->next == lid)
			tblk->next = tlck->next;
		else {
			for (prev = lid_to_tlock(tblk->next);
			     prev->next != lid;
			     prev = lid_to_tlock(prev->next)) {
				assert(prev->next);
			}
			prev->next = tlck->next;
		}
		lid_to_tlock(tblk->last)->next = lid;
		tlck->next = 0;
		tblk->last = lid;
	}

	/*
	 * parent page become empty: free the page
	 */
	if (index == XTENTRYSTART) {
		if (log) {	/* COMMIT_PWMAP */
			/* txCommit() with tlckFREE:
			 * free child extents covered by parent;
			 * invalidate parent if COMMIT_PWMAP;
			 */
			tlck = txLock(tid, ip, mp, tlckXTREE);
			xtlck = (struct xtlock *) & tlck->lock;
			xtlck->hwm.offset =
			    le16_to_cpu(p->header.nextindex) - 1;
			tlck->type = tlckXTREE | tlckFREE;
		} else {	/* COMMIT_WMAP */

			/* free child extents covered by parent */
			xadlock.xdlist = &p->xad[XTENTRYSTART];
			xadlock.count =
			    le16_to_cpu(p->header.nextindex) -
			    XTENTRYSTART;
			txFreeMap(ip, (struct maplock *) & xadlock, NULL,
				  COMMIT_WMAP);
		}
		BT_MARK_DIRTY(mp, ip);

		if (p->header.flag & BT_ROOT) {
			p->header.flag &= ~BT_INTERNAL;
			p->header.flag |= BT_LEAF;
			p->header.nextindex = cpu_to_le16(XTENTRYSTART);
			if (le16_to_cpu(p->header.maxentry) == XTROOTMAXSLOT) {
				/*
				 * Shrink root down to allow inline
				 * EA (otherwise fsck complains)
				 */
				p->header.maxentry =
				    cpu_to_le16(XTROOTINITSLOT);
				JFS_IP(ip)->mode2 |= INLINEEA;
			}

			XT_PUTPAGE(mp);	/* debug */
			goto out;
		} else {
			if (log) {	/* COMMIT_PWMAP */
				/* page will be invalidated at tx completion
				 */
				XT_PUTPAGE(mp);
			} else {	/* COMMIT_WMAP */

				if (mp->lid)
					lid_to_tlock(mp->lid)->flag |=
						tlckFREELOCK;

				/* invalidate parent page */
				discard_metapage(mp);
			}

			/* parent has become empty and freed:
			 * go back up to its parent page
			 */
			/* freed = 1; */
			goto getParent;
		}
	}
	/*
	 * parent page still has entries for front region;
	 */
	else {
		/* try truncate region covered by preceding entry
		 * (process backward)
		 */
		index--;

		/* go back down to the child page corresponding
		 * to the entry
		 */
		goto getChild;
	}

	/*
	 *      internal page: go down to child page of current entry
	 */
      getChild:
	/* save current parent entry for the child page */
	BT_PUSH(&btstack, bn, index);

	/* get child page */
	xad = &p->xad[index];
	bn = addressXAD(xad);

	/*
	 * first access of each internal entry:
	 */
	/* release parent page */
	XT_PUTPAGE(mp);

	/* process the child page */
	goto getPage;

      out:
	/*
	 * update file resource stat
	 */
	/* set size
	 */
	if (S_ISDIR(ip->i_mode) && !newsize)
		ip->i_size = 1;	/* fsck hates zero-length directories */
	else
		ip->i_size = newsize;

	/* update quota allocation to reflect freed blocks */
	DQUOT_FREE_BLOCK(ip, nfreed);

	/*
	 * free tlock of invalidated pages
	 */
	if (flag == COMMIT_WMAP)
		txFreelock(ip);

	return newsize;
}


/*
 *      xtTruncate_pmap()
 *
 * function:
 *	Perform truncate to zero lenghth for deleted file, leaving the
 *	the xtree and working map untouched.  This allows the file to
 *	be accessed via open file handles, while the delete of the file
 *	is committed to disk.
 *
 * parameter:
 *      tid_t		tid,
 *      struct inode	*ip,
 *      s64		committed_size)
 *
 * return: new committed size
 *
 * note:
 *
 *	To avoid deadlock by holding too many transaction locks, the
 *	truncation may be broken up into multiple transactions.
 *	The committed_size keeps track of part of the file has been
 *	freed from the pmaps.
 */
s64 xtTruncate_pmap(tid_t tid, struct inode *ip, s64 committed_size)
{
	s64 bn;
	struct btstack btstack;
	int cmp;
	int index;
	int locked_leaves = 0;
	struct metapage *mp;
	xtpage_t *p;
	struct btframe *parent;
	int rc;
	struct tblock *tblk;
	struct tlock *tlck = NULL;
	xad_t *xad;
	int xlen;
	s64 xoff;
	struct xtlock *xtlck = NULL;

	/* save object truncation type */
	tblk = tid_to_tblock(tid);
	tblk->xflag |= COMMIT_PMAP;

	/* clear stack */
	BT_CLR(&btstack);

	if (committed_size) {
		xoff = (committed_size >> JFS_SBI(ip->i_sb)->l2bsize) - 1;
		rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0);
		if (rc)
			return rc;

		XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

		if (cmp != 0) {
			XT_PUTPAGE(mp);
			jfs_error(ip->i_sb,
				  "xtTruncate_pmap: did not find extent");
			return -EIO;
		}
	} else {
		/*
		 * start with root
		 *
		 * root resides in the inode
		 */
		bn = 0;

		/*
		 * first access of each page:
		 */
      getPage:
		XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
		if (rc)
			return rc;

		/* process entries backward from last index */
		index = le16_to_cpu(p->header.nextindex) - 1;

		if (p->header.flag & BT_INTERNAL)
			goto getChild;
	}

	/*
	 *      leaf page
	 */

	if (++locked_leaves > MAX_TRUNCATE_LEAVES) {
		/*
		 * We need to limit the size of the transaction
		 * to avoid exhausting pagecache & tlocks
		 */
		xad = &p->xad[index];
		xoff = offsetXAD(xad);
		xlen = lengthXAD(xad);
		XT_PUTPAGE(mp);
		return  (xoff + xlen) << JFS_SBI(ip->i_sb)->l2bsize;
	}
	tlck = txLock(tid, ip, mp, tlckXTREE);
	tlck->type = tlckXTREE | tlckFREE;
	xtlck = (struct xtlock *) & tlck->lock;
	xtlck->hwm.offset = index;


	XT_PUTPAGE(mp);

	/*
	 * go back up to the parent page
	 */
      getParent:
	/* pop/restore parent entry for the current child page */
	if ((parent = BT_POP(&btstack)) == NULL)
		/* current page must have been root */
		goto out;

	/* get back the parent page */
	bn = parent->bn;
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	index = parent->index;

	/*
	 * parent page become empty: free the page
	 */
	if (index == XTENTRYSTART) {
		/* txCommit() with tlckFREE:
		 * free child extents covered by parent;
		 * invalidate parent if COMMIT_PWMAP;
		 */
		tlck = txLock(tid, ip, mp, tlckXTREE);
		xtlck = (struct xtlock *) & tlck->lock;
		xtlck->hwm.offset =
		    le16_to_cpu(p->header.nextindex) - 1;
		tlck->type = tlckXTREE | tlckFREE;

		XT_PUTPAGE(mp);

		if (p->header.flag & BT_ROOT) {

			goto out;
		} else {
			goto getParent;
		}
	}
	/*
	 * parent page still has entries for front region;
	 */
	else
		index--;
	/*
	 *      internal page: go down to child page of current entry
	 */
      getChild:
	/* save current parent entry for the child page */
	BT_PUSH(&btstack, bn, index);

	/* get child page */
	xad = &p->xad[index];
	bn = addressXAD(xad);

	/*
	 * first access of each internal entry:
	 */
	/* release parent page */
	XT_PUTPAGE(mp);

	/* process the child page */
	goto getPage;

      out:

	return 0;
}


#ifdef _JFS_DEBUG_XTREE
/*
 *      xtDisplayTree()
 *
 * function: traverse forward
 */
int xtDisplayTree(struct inode *ip)
{
	int rc = 0;
	struct metapage *mp;
	xtpage_t *p;
	s64 bn, pbn;
	int index, lastindex, v, h;
	xad_t *xad;
	struct btstack btstack;
	struct btframe *btsp;
	struct btframe *parent;

	printk("display B+-tree.\n");

	/* clear stack */
	btsp = btstack.stack;

	/*
	 * start with root
	 *
	 * root resides in the inode
	 */
	bn = 0;
	v = h = 0;

	/*
	 * first access of each page:
	 */
      getPage:
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	/* process entries forward from first index */
	index = XTENTRYSTART;
	lastindex = le16_to_cpu(p->header.nextindex) - 1;

	if (p->header.flag & BT_INTERNAL) {
		/*
		 * first access of each internal page
		 */
		goto getChild;
	} else {		/* (p->header.flag & BT_LEAF) */

		/*
		 * first access of each leaf page
		 */
		printf("leaf page ");
		xtDisplayPage(ip, bn, p);

		/* unpin the leaf page */
		XT_PUTPAGE(mp);
	}

	/*
	 * go back up to the parent page
	 */
      getParent:
	/* pop/restore parent entry for the current child page */
	if ((parent = (btsp == btstack.stack ? NULL : --btsp)) == NULL)
		/* current page must have been root */
		return;

	/*
	 * parent page scan completed
	 */
	if ((index = parent->index) == (lastindex = parent->lastindex)) {
		/* go back up to the parent page */
		goto getParent;
	}

	/*
	 * parent page has entries remaining
	 */
	/* get back the parent page */
	bn = parent->bn;
	/* v = parent->level; */
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	/* get next parent entry */
	index++;

	/*
	 * internal page: go down to child page of current entry
	 */
      getChild:
	/* push/save current parent entry for the child page */
	btsp->bn = pbn = bn;
	btsp->index = index;
	btsp->lastindex = lastindex;
	/* btsp->level = v; */
	/* btsp->node = h; */
	++btsp;

	/* get child page */
	xad = &p->xad[index];
	bn = addressXAD(xad);

	/*
	 * first access of each internal entry:
	 */
	/* release parent page */
	XT_PUTPAGE(mp);

	printk("traverse down 0x%lx[%d]->0x%lx\n", (ulong) pbn, index,
	       (ulong) bn);
	v++;
	h = index;

	/* process the child page */
	goto getPage;
}


/*
 *      xtDisplayPage()
 *
 * function: display page
 */
int xtDisplayPage(struct inode *ip, s64 bn, xtpage_t * p)
{
	int rc = 0;
	xad_t *xad;
	s64 xaddr, xoff;
	int xlen, i, j;

	/* display page control */
	printf("bn:0x%lx flag:0x%x nextindex:%d\n",
	       (ulong) bn, p->header.flag,
	       le16_to_cpu(p->header.nextindex));

	/* display entries */
	xad = &p->xad[XTENTRYSTART];
		for (i = XTENTRYSTART, j = 1; i < le16_to_cpu(p->header.nextindex);
		     i++, xad++, j++) {
			xoff = offsetXAD(xad);
			xaddr = addressXAD(xad);
			xlen = lengthXAD(xad);
			printf("\t[%d] 0x%lx:0x%lx(0x%x)", i, (ulong) xoff,
			       (ulong) xaddr, xlen);

			if (j == 4) {
				printf("\n");
				j = 0;
		}
	}

	printf("\n");
}
#endif				/* _JFS_DEBUG_XTREE */


#ifdef _JFS_WIP
/*
 *      xtGather()
 *
 * function:
 *      traverse for allocation acquiring tlock at commit time
 *      (vs at the time of update) logging backward top down
 *
 * note:
 *      problem - establishing that all new allocation have been
 *      processed both for append and random write in sparse file
 *      at the current entry at the current subtree root page
 *
 */
int xtGather(btree_t *t)
{
	int rc = 0;
	xtpage_t *p;
	u64 bn;
	int index;
	btentry_t *e;
	struct btstack btstack;
	struct btsf *parent;

	/* clear stack */
	BT_CLR(&btstack);

	/*
	 * start with root
	 *
	 * root resides in the inode
	 */
	bn = 0;
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	/* new root is NOT pointed by a new entry
	   if (p->header.flag & NEW)
	   allocate new page lock;
	   write a NEWPAGE log;
	 */

      dopage:
	/*
	 * first access of each page:
	 */
	/* process entries backward from last index */
	index = le16_to_cpu(p->header.nextindex) - 1;

	if (p->header.flag & BT_LEAF) {
		/*
		 * first access of each leaf page
		 */
		/* process leaf page entries backward */
		for (; index >= XTENTRYSTART; index--) {
			e = &p->xad[index];
			/*
			 * if newpage, log NEWPAGE.
			 *
			 if (e->flag & XAD_NEW) {
			 nfound =+ entry->length;
			 update current page lock for the entry;
			 newpage(entry);
			 *
			 * if moved, log move.
			 *
			 } else if (e->flag & XAD_MOVED) {
			 reset flag;
			 update current page lock for the entry;
			 }
			 */
		}

		/* unpin the leaf page */
		XT_PUTPAGE(mp);

		/*
		 * go back up to the parent page
		 */
	      getParent:
		/* restore parent entry for the current child page */
		if ((parent = BT_POP(&btstack)) == NULL)
			/* current page must have been root */
			return 0;

		if ((index = parent->index) == XTENTRYSTART) {
			/*
			 * parent page scan completed
			 */
			/* go back up to the parent page */
			goto getParent;
		} else {
			/*
			 * parent page has entries remaining
			 */
			/* get back the parent page */
			bn = parent->bn;
			XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
			if (rc)
				return -EIO;

			/* first subroot page which
			 * covers all new allocated blocks
			 * itself not new/modified.
			 * (if modified from split of descendent,
			 * go down path of split page)

			 if (nfound == nnew &&
			 !(p->header.flag & (NEW | MOD)))
			 exit scan;
			 */

			/* process parent page entries backward */
			index--;
		}
	} else {
		/*
		 * first access of each internal page
		 */
	}

	/*
	 * internal page: go down to child page of current entry
	 */

	/* save current parent entry for the child page */
	BT_PUSH(&btstack, bn, index);

	/* get current entry for the child page */
	e = &p->xad[index];

	/*
	 * first access of each internal entry:
	 */
	/*
	 * if new entry, log btree_tnewentry.
	 *
	 if (e->flag & XAD_NEW)
	 update parent page lock for the entry;
	 */

	/* release parent page */
	XT_PUTPAGE(mp);

	/* get child page */
	bn = e->bn;
	XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
	if (rc)
		return rc;

	/*
	 * first access of each non-root page:
	 */
	/*
	 * if new, log btree_newpage.
	 *
	 if (p->header.flag & NEW)
	 allocate new page lock;
	 write a NEWPAGE log (next, prev);
	 */

	/* process the child page */
	goto dopage;

      out:
	return 0;
}
#endif				/* _JFS_WIP */


#ifdef CONFIG_JFS_STATISTICS
int jfs_xtstat_read(char *buffer, char **start, off_t offset, int length,
		    int *eof, void *data)
{
	int len = 0;
	off_t begin;

	len += sprintf(buffer,
		       "JFS Xtree statistics\n"
		       "====================\n"
		       "searches = %d\n"
		       "fast searches = %d\n"
		       "splits = %d\n",
		       xtStat.search,
		       xtStat.fastSearch,
		       xtStat.split);

	begin = offset;
	*start = buffer + begin;
	len -= begin;

	if (len > length)
		len = length;
	else
		*eof = 1;

	if (len < 0)
		len = 0;

	return len;
}
#endif