summaryrefslogtreecommitdiffstats
path: root/fs/ext4/extents.c
blob: dc2724fa7622b2b1492d0d547425e6dcc1e7e35c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
/*
 * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
 * Written by Alex Tomas <alex@clusterfs.com>
 *
 * Architecture independence:
 *   Copyright (c) 2005, Bull S.A.
 *   Written by Pierre Peiffer <pierre.peiffer@bull.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public Licens
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 */

/*
 * Extents support for EXT4
 *
 * TODO:
 *   - ext4*_error() should be used in some situations
 *   - analyze all BUG()/BUG_ON(), use -EIO where appropriate
 *   - smart tree reduction
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/ext4_jbd2.h>
#include <linux/jbd.h>
#include <linux/smp_lock.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/ext4_fs_extents.h>
#include <asm/uaccess.h>


/*
 * ext_pblock:
 * combine low and high parts of physical block number into ext4_fsblk_t
 */
static ext4_fsblk_t ext_pblock(struct ext4_extent *ex)
{
	ext4_fsblk_t block;

	block = le32_to_cpu(ex->ee_start);
	block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
	return block;
}

/*
 * idx_pblock:
 * combine low and high parts of a leaf physical block number into ext4_fsblk_t
 */
static ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
{
	ext4_fsblk_t block;

	block = le32_to_cpu(ix->ei_leaf);
	block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
	return block;
}

/*
 * ext4_ext_store_pblock:
 * stores a large physical block number into an extent struct,
 * breaking it into parts
 */
static void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb)
{
	ex->ee_start = cpu_to_le32((unsigned long) (pb & 0xffffffff));
	ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
}

/*
 * ext4_idx_store_pblock:
 * stores a large physical block number into an index struct,
 * breaking it into parts
 */
static void ext4_idx_store_pblock(struct ext4_extent_idx *ix, ext4_fsblk_t pb)
{
	ix->ei_leaf = cpu_to_le32((unsigned long) (pb & 0xffffffff));
	ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
}

static int ext4_ext_check_header(const char *function, struct inode *inode,
				struct ext4_extent_header *eh)
{
	const char *error_msg = NULL;

	if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
		error_msg = "invalid magic";
		goto corrupted;
	}
	if (unlikely(eh->eh_max == 0)) {
		error_msg = "invalid eh_max";
		goto corrupted;
	}
	if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
		error_msg = "invalid eh_entries";
		goto corrupted;
	}
	return 0;

corrupted:
	ext4_error(inode->i_sb, function,
			"bad header in inode #%lu: %s - magic %x, "
			"entries %u, max %u, depth %u",
			inode->i_ino, error_msg, le16_to_cpu(eh->eh_magic),
			le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max),
			le16_to_cpu(eh->eh_depth));

	return -EIO;
}

static handle_t *ext4_ext_journal_restart(handle_t *handle, int needed)
{
	int err;

	if (handle->h_buffer_credits > needed)
		return handle;
	if (!ext4_journal_extend(handle, needed))
		return handle;
	err = ext4_journal_restart(handle, needed);

	return handle;
}

/*
 * could return:
 *  - EROFS
 *  - ENOMEM
 */
static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
				struct ext4_ext_path *path)
{
	if (path->p_bh) {
		/* path points to block */
		return ext4_journal_get_write_access(handle, path->p_bh);
	}
	/* path points to leaf/index in inode body */
	/* we use in-core data, no need to protect them */
	return 0;
}

/*
 * could return:
 *  - EROFS
 *  - ENOMEM
 *  - EIO
 */
static int ext4_ext_dirty(handle_t *handle, struct inode *inode,
				struct ext4_ext_path *path)
{
	int err;
	if (path->p_bh) {
		/* path points to block */
		err = ext4_journal_dirty_metadata(handle, path->p_bh);
	} else {
		/* path points to leaf/index in inode body */
		err = ext4_mark_inode_dirty(handle, inode);
	}
	return err;
}

static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
			      struct ext4_ext_path *path,
			      ext4_fsblk_t block)
{
	struct ext4_inode_info *ei = EXT4_I(inode);
	ext4_fsblk_t bg_start;
	ext4_grpblk_t colour;
	int depth;

	if (path) {
		struct ext4_extent *ex;
		depth = path->p_depth;

		/* try to predict block placement */
		ex = path[depth].p_ext;
		if (ex)
			return ext_pblock(ex)+(block-le32_to_cpu(ex->ee_block));

		/* it looks like index is empty;
		 * try to find starting block from index itself */
		if (path[depth].p_bh)
			return path[depth].p_bh->b_blocknr;
	}

	/* OK. use inode's group */
	bg_start = (ei->i_block_group * EXT4_BLOCKS_PER_GROUP(inode->i_sb)) +
		le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_first_data_block);
	colour = (current->pid % 16) *
			(EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
	return bg_start + colour + block;
}

static ext4_fsblk_t
ext4_ext_new_block(handle_t *handle, struct inode *inode,
			struct ext4_ext_path *path,
			struct ext4_extent *ex, int *err)
{
	ext4_fsblk_t goal, newblock;

	goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
	newblock = ext4_new_block(handle, inode, goal, err);
	return newblock;
}

static int ext4_ext_space_block(struct inode *inode)
{
	int size;

	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
			/ sizeof(struct ext4_extent);
#ifdef AGRESSIVE_TEST
	if (size > 6)
		size = 6;
#endif
	return size;
}

static int ext4_ext_space_block_idx(struct inode *inode)
{
	int size;

	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
			/ sizeof(struct ext4_extent_idx);
#ifdef AGRESSIVE_TEST
	if (size > 5)
		size = 5;
#endif
	return size;
}

static int ext4_ext_space_root(struct inode *inode)
{
	int size;

	size = sizeof(EXT4_I(inode)->i_data);
	size -= sizeof(struct ext4_extent_header);
	size /= sizeof(struct ext4_extent);
#ifdef AGRESSIVE_TEST
	if (size > 3)
		size = 3;
#endif
	return size;
}

static int ext4_ext_space_root_idx(struct inode *inode)
{
	int size;

	size = sizeof(EXT4_I(inode)->i_data);
	size -= sizeof(struct ext4_extent_header);
	size /= sizeof(struct ext4_extent_idx);
#ifdef AGRESSIVE_TEST
	if (size > 4)
		size = 4;
#endif
	return size;
}

#ifdef EXT_DEBUG
static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
{
	int k, l = path->p_depth;

	ext_debug("path:");
	for (k = 0; k <= l; k++, path++) {
		if (path->p_idx) {
		  ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
			    idx_pblock(path->p_idx));
		} else if (path->p_ext) {
			ext_debug("  %d:%d:%llu ",
				  le32_to_cpu(path->p_ext->ee_block),
				  le16_to_cpu(path->p_ext->ee_len),
				  ext_pblock(path->p_ext));
		} else
			ext_debug("  []");
	}
	ext_debug("\n");
}

static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
{
	int depth = ext_depth(inode);
	struct ext4_extent_header *eh;
	struct ext4_extent *ex;
	int i;

	if (!path)
		return;

	eh = path[depth].p_hdr;
	ex = EXT_FIRST_EXTENT(eh);

	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
		ext_debug("%d:%d:%llu ", le32_to_cpu(ex->ee_block),
			  le16_to_cpu(ex->ee_len), ext_pblock(ex));
	}
	ext_debug("\n");
}
#else
#define ext4_ext_show_path(inode,path)
#define ext4_ext_show_leaf(inode,path)
#endif

static void ext4_ext_drop_refs(struct ext4_ext_path *path)
{
	int depth = path->p_depth;
	int i;

	for (i = 0; i <= depth; i++, path++)
		if (path->p_bh) {
			brelse(path->p_bh);
			path->p_bh = NULL;
		}
}

/*
 * ext4_ext_binsearch_idx:
 * binary search for the closest index of the given block
 */
static void
ext4_ext_binsearch_idx(struct inode *inode, struct ext4_ext_path *path, int block)
{
	struct ext4_extent_header *eh = path->p_hdr;
	struct ext4_extent_idx *r, *l, *m;

	BUG_ON(eh->eh_magic != EXT4_EXT_MAGIC);
	BUG_ON(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max));
	BUG_ON(le16_to_cpu(eh->eh_entries) <= 0);

	ext_debug("binsearch for %d(idx):  ", block);

	l = EXT_FIRST_INDEX(eh) + 1;
	r = EXT_FIRST_INDEX(eh) + le16_to_cpu(eh->eh_entries) - 1;
	while (l <= r) {
		m = l + (r - l) / 2;
		if (block < le32_to_cpu(m->ei_block))
			r = m - 1;
		else
			l = m + 1;
		ext_debug("%p(%u):%p(%u):%p(%u) ", l, l->ei_block,
				m, m->ei_block, r, r->ei_block);
	}

	path->p_idx = l - 1;
	ext_debug("  -> %d->%lld ", le32_to_cpu(path->p_idx->ei_block),
		  idx_block(path->p_idx));

#ifdef CHECK_BINSEARCH
	{
		struct ext4_extent_idx *chix, *ix;
		int k;

		chix = ix = EXT_FIRST_INDEX(eh);
		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
		  if (k != 0 &&
		      le32_to_cpu(ix->ei_block) <= le32_to_cpu(ix[-1].ei_block)) {
				printk("k=%d, ix=0x%p, first=0x%p\n", k,
					ix, EXT_FIRST_INDEX(eh));
				printk("%u <= %u\n",
				       le32_to_cpu(ix->ei_block),
				       le32_to_cpu(ix[-1].ei_block));
			}
			BUG_ON(k && le32_to_cpu(ix->ei_block)
				           <= le32_to_cpu(ix[-1].ei_block));
			if (block < le32_to_cpu(ix->ei_block))
				break;
			chix = ix;
		}
		BUG_ON(chix != path->p_idx);
	}
#endif

}

/*
 * ext4_ext_binsearch:
 * binary search for closest extent of the given block
 */
static void
ext4_ext_binsearch(struct inode *inode, struct ext4_ext_path *path, int block)
{
	struct ext4_extent_header *eh = path->p_hdr;
	struct ext4_extent *r, *l, *m;

	BUG_ON(eh->eh_magic != EXT4_EXT_MAGIC);
	BUG_ON(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max));

	if (eh->eh_entries == 0) {
		/*
		 * this leaf is empty:
		 * we get such a leaf in split/add case
		 */
		return;
	}

	ext_debug("binsearch for %d:  ", block);

	l = EXT_FIRST_EXTENT(eh) + 1;
	r = EXT_FIRST_EXTENT(eh) + le16_to_cpu(eh->eh_entries) - 1;

	while (l <= r) {
		m = l + (r - l) / 2;
		if (block < le32_to_cpu(m->ee_block))
			r = m - 1;
		else
			l = m + 1;
		ext_debug("%p(%u):%p(%u):%p(%u) ", l, l->ee_block,
				m, m->ee_block, r, r->ee_block);
	}

	path->p_ext = l - 1;
	ext_debug("  -> %d:%llu:%d ",
		        le32_to_cpu(path->p_ext->ee_block),
		        ext_pblock(path->p_ext),
			le16_to_cpu(path->p_ext->ee_len));

#ifdef CHECK_BINSEARCH
	{
		struct ext4_extent *chex, *ex;
		int k;

		chex = ex = EXT_FIRST_EXTENT(eh);
		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
			BUG_ON(k && le32_to_cpu(ex->ee_block)
				          <= le32_to_cpu(ex[-1].ee_block));
			if (block < le32_to_cpu(ex->ee_block))
				break;
			chex = ex;
		}
		BUG_ON(chex != path->p_ext);
	}
#endif

}

int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
{
	struct ext4_extent_header *eh;

	eh = ext_inode_hdr(inode);
	eh->eh_depth = 0;
	eh->eh_entries = 0;
	eh->eh_magic = EXT4_EXT_MAGIC;
	eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode));
	ext4_mark_inode_dirty(handle, inode);
	ext4_ext_invalidate_cache(inode);
	return 0;
}

struct ext4_ext_path *
ext4_ext_find_extent(struct inode *inode, int block, struct ext4_ext_path *path)
{
	struct ext4_extent_header *eh;
	struct buffer_head *bh;
	short int depth, i, ppos = 0, alloc = 0;

	eh = ext_inode_hdr(inode);
	BUG_ON(eh == NULL);
	if (ext4_ext_check_header(__FUNCTION__, inode, eh))
		return ERR_PTR(-EIO);

	i = depth = ext_depth(inode);

	/* account possible depth increase */
	if (!path) {
		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
				GFP_NOFS);
		if (!path)
			return ERR_PTR(-ENOMEM);
		alloc = 1;
	}
	path[0].p_hdr = eh;

	/* walk through the tree */
	while (i) {
		ext_debug("depth %d: num %d, max %d\n",
			  ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
		ext4_ext_binsearch_idx(inode, path + ppos, block);
		path[ppos].p_block = idx_pblock(path[ppos].p_idx);
		path[ppos].p_depth = i;
		path[ppos].p_ext = NULL;

		bh = sb_bread(inode->i_sb, path[ppos].p_block);
		if (!bh)
			goto err;

		eh = ext_block_hdr(bh);
		ppos++;
		BUG_ON(ppos > depth);
		path[ppos].p_bh = bh;
		path[ppos].p_hdr = eh;
		i--;

		if (ext4_ext_check_header(__FUNCTION__, inode, eh))
			goto err;
	}

	path[ppos].p_depth = i;
	path[ppos].p_hdr = eh;
	path[ppos].p_ext = NULL;
	path[ppos].p_idx = NULL;

	if (ext4_ext_check_header(__FUNCTION__, inode, eh))
		goto err;

	/* find extent */
	ext4_ext_binsearch(inode, path + ppos, block);

	ext4_ext_show_path(inode, path);

	return path;

err:
	ext4_ext_drop_refs(path);
	if (alloc)
		kfree(path);
	return ERR_PTR(-EIO);
}

/*
 * ext4_ext_insert_index:
 * insert new index [@logical;@ptr] into the block at @curp;
 * check where to insert: before @curp or after @curp
 */
static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
				struct ext4_ext_path *curp,
				int logical, ext4_fsblk_t ptr)
{
	struct ext4_extent_idx *ix;
	int len, err;

	err = ext4_ext_get_access(handle, inode, curp);
	if (err)
		return err;

	BUG_ON(logical == le32_to_cpu(curp->p_idx->ei_block));
	len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
	if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
		/* insert after */
		if (curp->p_idx != EXT_LAST_INDEX(curp->p_hdr)) {
			len = (len - 1) * sizeof(struct ext4_extent_idx);
			len = len < 0 ? 0 : len;
			ext_debug("insert new index %d after: %d. "
					"move %d from 0x%p to 0x%p\n",
					logical, ptr, len,
					(curp->p_idx + 1), (curp->p_idx + 2));
			memmove(curp->p_idx + 2, curp->p_idx + 1, len);
		}
		ix = curp->p_idx + 1;
	} else {
		/* insert before */
		len = len * sizeof(struct ext4_extent_idx);
		len = len < 0 ? 0 : len;
		ext_debug("insert new index %d before: %d. "
				"move %d from 0x%p to 0x%p\n",
				logical, ptr, len,
				curp->p_idx, (curp->p_idx + 1));
		memmove(curp->p_idx + 1, curp->p_idx, len);
		ix = curp->p_idx;
	}

	ix->ei_block = cpu_to_le32(logical);
	ext4_idx_store_pblock(ix, ptr);
	curp->p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(curp->p_hdr->eh_entries)+1);

	BUG_ON(le16_to_cpu(curp->p_hdr->eh_entries)
	                     > le16_to_cpu(curp->p_hdr->eh_max));
	BUG_ON(ix > EXT_LAST_INDEX(curp->p_hdr));

	err = ext4_ext_dirty(handle, inode, curp);
	ext4_std_error(inode->i_sb, err);

	return err;
}

/*
 * ext4_ext_split:
 * inserts new subtree into the path, using free index entry
 * at depth @at:
 * - allocates all needed blocks (new leaf and all intermediate index blocks)
 * - makes decision where to split
 * - moves remaining extents and index entries (right to the split point)
 *   into the newly allocated blocks
 * - initializes subtree
 */
static int ext4_ext_split(handle_t *handle, struct inode *inode,
				struct ext4_ext_path *path,
				struct ext4_extent *newext, int at)
{
	struct buffer_head *bh = NULL;
	int depth = ext_depth(inode);
	struct ext4_extent_header *neh;
	struct ext4_extent_idx *fidx;
	struct ext4_extent *ex;
	int i = at, k, m, a;
	ext4_fsblk_t newblock, oldblock;
	__le32 border;
	ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
	int err = 0;

	/* make decision: where to split? */
	/* FIXME: now decision is simplest: at current extent */

	/* if current leaf will be split, then we should use
	 * border from split point */
	BUG_ON(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr));
	if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
		border = path[depth].p_ext[1].ee_block;
		ext_debug("leaf will be split."
				" next leaf starts at %d\n",
			          le32_to_cpu(border));
	} else {
		border = newext->ee_block;
		ext_debug("leaf will be added."
				" next leaf starts at %d\n",
			        le32_to_cpu(border));
	}

	/*
	 * If error occurs, then we break processing
	 * and mark filesystem read-only. index won't
	 * be inserted and tree will be in consistent
	 * state. Next mount will repair buffers too.
	 */

	/*
	 * Get array to track all allocated blocks.
	 * We need this to handle errors and free blocks
	 * upon them.
	 */
	ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
	if (!ablocks)
		return -ENOMEM;

	/* allocate all needed blocks */
	ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
	for (a = 0; a < depth - at; a++) {
		newblock = ext4_ext_new_block(handle, inode, path, newext, &err);
		if (newblock == 0)
			goto cleanup;
		ablocks[a] = newblock;
	}

	/* initialize new leaf */
	newblock = ablocks[--a];
	BUG_ON(newblock == 0);
	bh = sb_getblk(inode->i_sb, newblock);
	if (!bh) {
		err = -EIO;
		goto cleanup;
	}
	lock_buffer(bh);

	err = ext4_journal_get_create_access(handle, bh);
	if (err)
		goto cleanup;

	neh = ext_block_hdr(bh);
	neh->eh_entries = 0;
	neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode));
	neh->eh_magic = EXT4_EXT_MAGIC;
	neh->eh_depth = 0;
	ex = EXT_FIRST_EXTENT(neh);

	/* move remainder of path[depth] to the new leaf */
	BUG_ON(path[depth].p_hdr->eh_entries != path[depth].p_hdr->eh_max);
	/* start copy from next extent */
	/* TODO: we could do it by single memmove */
	m = 0;
	path[depth].p_ext++;
	while (path[depth].p_ext <=
			EXT_MAX_EXTENT(path[depth].p_hdr)) {
		ext_debug("move %d:%llu:%d in new leaf %llu\n",
			        le32_to_cpu(path[depth].p_ext->ee_block),
			        ext_pblock(path[depth].p_ext),
			        le16_to_cpu(path[depth].p_ext->ee_len),
				newblock);
		/*memmove(ex++, path[depth].p_ext++,
				sizeof(struct ext4_extent));
		neh->eh_entries++;*/
		path[depth].p_ext++;
		m++;
	}
	if (m) {
		memmove(ex, path[depth].p_ext-m, sizeof(struct ext4_extent)*m);
		neh->eh_entries = cpu_to_le16(le16_to_cpu(neh->eh_entries)+m);
	}

	set_buffer_uptodate(bh);
	unlock_buffer(bh);

	err = ext4_journal_dirty_metadata(handle, bh);
	if (err)
		goto cleanup;
	brelse(bh);
	bh = NULL;

	/* correct old leaf */
	if (m) {
		err = ext4_ext_get_access(handle, inode, path + depth);
		if (err)
			goto cleanup;
		path[depth].p_hdr->eh_entries =
		     cpu_to_le16(le16_to_cpu(path[depth].p_hdr->eh_entries)-m);
		err = ext4_ext_dirty(handle, inode, path + depth);
		if (err)
			goto cleanup;

	}

	/* create intermediate indexes */
	k = depth - at - 1;
	BUG_ON(k < 0);
	if (k)
		ext_debug("create %d intermediate indices\n", k);
	/* insert new index into current index block */
	/* current depth stored in i var */
	i = depth - 1;
	while (k--) {
		oldblock = newblock;
		newblock = ablocks[--a];
		bh = sb_getblk(inode->i_sb, (ext4_fsblk_t)newblock);
		if (!bh) {
			err = -EIO;
			goto cleanup;
		}
		lock_buffer(bh);

		err = ext4_journal_get_create_access(handle, bh);
		if (err)
			goto cleanup;

		neh = ext_block_hdr(bh);
		neh->eh_entries = cpu_to_le16(1);
		neh->eh_magic = EXT4_EXT_MAGIC;
		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode));
		neh->eh_depth = cpu_to_le16(depth - i);
		fidx = EXT_FIRST_INDEX(neh);
		fidx->ei_block = border;
		ext4_idx_store_pblock(fidx, oldblock);

		ext_debug("int.index at %d (block %llu): %lu -> %llu\n", i,
				newblock, (unsigned long) le32_to_cpu(border),
				oldblock);
		/* copy indexes */
		m = 0;
		path[i].p_idx++;

		ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
				EXT_MAX_INDEX(path[i].p_hdr));
		BUG_ON(EXT_MAX_INDEX(path[i].p_hdr) !=
				EXT_LAST_INDEX(path[i].p_hdr));
		while (path[i].p_idx <= EXT_MAX_INDEX(path[i].p_hdr)) {
			ext_debug("%d: move %d:%d in new index %llu\n", i,
				        le32_to_cpu(path[i].p_idx->ei_block),
				        idx_pblock(path[i].p_idx),
				        newblock);
			/*memmove(++fidx, path[i].p_idx++,
					sizeof(struct ext4_extent_idx));
			neh->eh_entries++;
			BUG_ON(neh->eh_entries > neh->eh_max);*/
			path[i].p_idx++;
			m++;
		}
		if (m) {
			memmove(++fidx, path[i].p_idx - m,
				sizeof(struct ext4_extent_idx) * m);
			neh->eh_entries =
				cpu_to_le16(le16_to_cpu(neh->eh_entries) + m);
		}
		set_buffer_uptodate(bh);
		unlock_buffer(bh);

		err = ext4_journal_dirty_metadata(handle, bh);
		if (err)
			goto cleanup;
		brelse(bh);
		bh = NULL;

		/* correct old index */
		if (m) {
			err = ext4_ext_get_access(handle, inode, path + i);
			if (err)
				goto cleanup;
			path[i].p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(path[i].p_hdr->eh_entries)-m);
			err = ext4_ext_dirty(handle, inode, path + i);
			if (err)
				goto cleanup;
		}

		i--;
	}

	/* insert new index */
	err = ext4_ext_insert_index(handle, inode, path + at,
				    le32_to_cpu(border), newblock);

cleanup:
	if (bh) {
		if (buffer_locked(bh))
			unlock_buffer(bh);
		brelse(bh);
	}

	if (err) {
		/* free all allocated blocks in error case */
		for (i = 0; i < depth; i++) {
			if (!ablocks[i])
				continue;
			ext4_free_blocks(handle, inode, ablocks[i], 1);
		}
	}
	kfree(ablocks);

	return err;
}

/*
 * ext4_ext_grow_indepth:
 * implements tree growing procedure:
 * - allocates new block
 * - moves top-level data (index block or leaf) into the new block
 * - initializes new top-level, creating index that points to the
 *   just created block
 */
static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
					struct ext4_ext_path *path,
					struct ext4_extent *newext)
{
	struct ext4_ext_path *curp = path;
	struct ext4_extent_header *neh;
	struct ext4_extent_idx *fidx;
	struct buffer_head *bh;
	ext4_fsblk_t newblock;
	int err = 0;

	newblock = ext4_ext_new_block(handle, inode, path, newext, &err);
	if (newblock == 0)
		return err;

	bh = sb_getblk(inode->i_sb, newblock);
	if (!bh) {
		err = -EIO;
		ext4_std_error(inode->i_sb, err);
		return err;
	}
	lock_buffer(bh);

	err = ext4_journal_get_create_access(handle, bh);
	if (err) {
		unlock_buffer(bh);
		goto out;
	}

	/* move top-level index/leaf into new block */
	memmove(bh->b_data, curp->p_hdr, sizeof(EXT4_I(inode)->i_data));

	/* set size of new block */
	neh = ext_block_hdr(bh);
	/* old root could have indexes or leaves
	 * so calculate e_max right way */
	if (ext_depth(inode))
	  neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode));
	else
	  neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode));
	neh->eh_magic = EXT4_EXT_MAGIC;
	set_buffer_uptodate(bh);
	unlock_buffer(bh);

	err = ext4_journal_dirty_metadata(handle, bh);
	if (err)
		goto out;

	/* create index in new top-level index: num,max,pointer */
	err = ext4_ext_get_access(handle, inode, curp);
	if (err)
		goto out;

	curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;
	curp->p_hdr->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode));
	curp->p_hdr->eh_entries = cpu_to_le16(1);
	curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
	/* FIXME: it works, but actually path[0] can be index */
	curp->p_idx->ei_block = EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;
	ext4_idx_store_pblock(curp->p_idx, newblock);

	neh = ext_inode_hdr(inode);
	fidx = EXT_FIRST_INDEX(neh);
	ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
		  le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
		  le32_to_cpu(fidx->ei_block), idx_pblock(fidx));

	neh->eh_depth = cpu_to_le16(path->p_depth + 1);
	err = ext4_ext_dirty(handle, inode, curp);
out:
	brelse(bh);

	return err;
}

/*
 * ext4_ext_create_new_leaf:
 * finds empty index and adds new leaf.
 * if no free index is found, then it requests in-depth growing.
 */
static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
					struct ext4_ext_path *path,
					struct ext4_extent *newext)
{
	struct ext4_ext_path *curp;
	int depth, i, err = 0;

repeat:
	i = depth = ext_depth(inode);

	/* walk up to the tree and look for free index entry */
	curp = path + depth;
	while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
		i--;
		curp--;
	}

	/* we use already allocated block for index block,
	 * so subsequent data blocks should be contiguous */
	if (EXT_HAS_FREE_INDEX(curp)) {
		/* if we found index with free entry, then use that
		 * entry: create all needed subtree and add new leaf */
		err = ext4_ext_split(handle, inode, path, newext, i);

		/* refill path */
		ext4_ext_drop_refs(path);
		path = ext4_ext_find_extent(inode,
					    le32_to_cpu(newext->ee_block),
					    path);
		if (IS_ERR(path))
			err = PTR_ERR(path);
	} else {
		/* tree is full, time to grow in depth */
		err = ext4_ext_grow_indepth(handle, inode, path, newext);
		if (err)
			goto out;

		/* refill path */
		ext4_ext_drop_refs(path);
		path = ext4_ext_find_extent(inode,
					    le32_to_cpu(newext->ee_block),
					    path);
		if (IS_ERR(path)) {
			err = PTR_ERR(path);
			goto out;
		}

		/*
		 * only first (depth 0 -> 1) produces free space;
		 * in all other cases we have to split the grown tree
		 */
		depth = ext_depth(inode);
		if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
			/* now we need to split */
			goto repeat;
		}
	}

out:
	return err;
}

/*
 * ext4_ext_next_allocated_block:
 * returns allocated block in subsequent extent or EXT_MAX_BLOCK.
 * NOTE: it considers block number from index entry as
 * allocated block. Thus, index entries have to be consistent
 * with leaves.
 */
static unsigned long
ext4_ext_next_allocated_block(struct ext4_ext_path *path)
{
	int depth;

	BUG_ON(path == NULL);
	depth = path->p_depth;

	if (depth == 0 && path->p_ext == NULL)
		return EXT_MAX_BLOCK;

	while (depth >= 0) {
		if (depth == path->p_depth) {
			/* leaf */
			if (path[depth].p_ext !=
					EXT_LAST_EXTENT(path[depth].p_hdr))
			  return le32_to_cpu(path[depth].p_ext[1].ee_block);
		} else {
			/* index */
			if (path[depth].p_idx !=
					EXT_LAST_INDEX(path[depth].p_hdr))
			  return le32_to_cpu(path[depth].p_idx[1].ei_block);
		}
		depth--;
	}

	return EXT_MAX_BLOCK;
}

/*
 * ext4_ext_next_leaf_block:
 * returns first allocated block from next leaf or EXT_MAX_BLOCK
 */
static unsigned ext4_ext_next_leaf_block(struct inode *inode,
					struct ext4_ext_path *path)
{
	int depth;

	BUG_ON(path == NULL);
	depth = path->p_depth;

	/* zero-tree has no leaf blocks at all */
	if (depth == 0)
		return EXT_MAX_BLOCK;

	/* go to index block */
	depth--;

	while (depth >= 0) {
		if (path[depth].p_idx !=
				EXT_LAST_INDEX(path[depth].p_hdr))
		  return le32_to_cpu(path[depth].p_idx[1].ei_block);
		depth--;
	}

	return EXT_MAX_BLOCK;
}

/*
 * ext4_ext_correct_indexes:
 * if leaf gets modified and modified extent is first in the leaf,
 * then we have to correct all indexes above.
 * TODO: do we need to correct tree in all cases?
 */
int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
				struct ext4_ext_path *path)
{
	struct ext4_extent_header *eh;
	int depth = ext_depth(inode);
	struct ext4_extent *ex;
	__le32 border;
	int k, err = 0;

	eh = path[depth].p_hdr;
	ex = path[depth].p_ext;
	BUG_ON(ex == NULL);
	BUG_ON(eh == NULL);

	if (depth == 0) {
		/* there is no tree at all */
		return 0;
	}

	if (ex != EXT_FIRST_EXTENT(eh)) {
		/* we correct tree if first leaf got modified only */
		return 0;
	}

	/*
	 * TODO: we need correction if border is smaller than current one
	 */
	k = depth - 1;
	border = path[depth].p_ext->ee_block;
	err = ext4_ext_get_access(handle, inode, path + k);
	if (err)
		return err;
	path[k].p_idx->ei_block = border;
	err = ext4_ext_dirty(handle, inode, path + k);
	if (err)
		return err;

	while (k--) {
		/* change all left-side indexes */
		if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
			break;
		err = ext4_ext_get_access(handle, inode, path + k);
		if (err)
			break;
		path[k].p_idx->ei_block = border;
		err = ext4_ext_dirty(handle, inode, path + k);
		if (err)
			break;
	}

	return err;
}

static int
ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
				struct ext4_extent *ex2)
{
	if (le32_to_cpu(ex1->ee_block) + le16_to_cpu(ex1->ee_len) !=
			le32_to_cpu(ex2->ee_block))
		return 0;

	/*
	 * To allow future support for preallocated extents to be added
	 * as an RO_COMPAT feature, refuse to merge to extents if
	 * this can result in the top bit of ee_len being set.
	 */
	if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
		return 0;
#ifdef AGRESSIVE_TEST
	if (le16_to_cpu(ex1->ee_len) >= 4)
		return 0;
#endif

	if (ext_pblock(ex1) + le16_to_cpu(ex1->ee_len) == ext_pblock(ex2))
		return 1;
	return 0;
}

/*
 * ext4_ext_insert_extent:
 * tries to merge requsted extent into the existing extent or
 * inserts requested extent as new one into the tree,
 * creating new leaf in the no-space case.
 */
int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
				struct ext4_ext_path *path,
				struct ext4_extent *newext)
{
	struct ext4_extent_header * eh;
	struct ext4_extent *ex, *fex;
	struct ext4_extent *nearex; /* nearest extent */
	struct ext4_ext_path *npath = NULL;
	int depth, len, err, next;

	BUG_ON(newext->ee_len == 0);
	depth = ext_depth(inode);
	ex = path[depth].p_ext;
	BUG_ON(path[depth].p_hdr == NULL);

	/* try to insert block into found extent and return */
	if (ex && ext4_can_extents_be_merged(inode, ex, newext)) {
		ext_debug("append %d block to %d:%d (from %llu)\n",
				le16_to_cpu(newext->ee_len),
				le32_to_cpu(ex->ee_block),
				le16_to_cpu(ex->ee_len), ext_pblock(ex));
		err = ext4_ext_get_access(handle, inode, path + depth);
		if (err)
			return err;
		ex->ee_len = cpu_to_le16(le16_to_cpu(ex->ee_len)
					 + le16_to_cpu(newext->ee_len));
		eh = path[depth].p_hdr;
		nearex = ex;
		goto merge;
	}

repeat:
	depth = ext_depth(inode);
	eh = path[depth].p_hdr;
	if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
		goto has_space;

	/* probably next leaf has space for us? */
	fex = EXT_LAST_EXTENT(eh);
	next = ext4_ext_next_leaf_block(inode, path);
	if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block)
	    && next != EXT_MAX_BLOCK) {
		ext_debug("next leaf block - %d\n", next);
		BUG_ON(npath != NULL);
		npath = ext4_ext_find_extent(inode, next, NULL);
		if (IS_ERR(npath))
			return PTR_ERR(npath);
		BUG_ON(npath->p_depth != path->p_depth);
		eh = npath[depth].p_hdr;
		if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
			ext_debug("next leaf isnt full(%d)\n",
				  le16_to_cpu(eh->eh_entries));
			path = npath;
			goto repeat;
		}
		ext_debug("next leaf has no free space(%d,%d)\n",
			  le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
	}

	/*
	 * There is no free space in the found leaf.
	 * We're gonna add a new leaf in the tree.
	 */
	err = ext4_ext_create_new_leaf(handle, inode, path, newext);
	if (err)
		goto cleanup;
	depth = ext_depth(inode);
	eh = path[depth].p_hdr;

has_space:
	nearex = path[depth].p_ext;

	err = ext4_ext_get_access(handle, inode, path + depth);
	if (err)
		goto cleanup;

	if (!nearex) {
		/* there is no extent in this leaf, create first one */
		ext_debug("first extent in the leaf: %d:%llu:%d\n",
			        le32_to_cpu(newext->ee_block),
			        ext_pblock(newext),
			        le16_to_cpu(newext->ee_len));
		path[depth].p_ext = EXT_FIRST_EXTENT(eh);
	} else if (le32_to_cpu(newext->ee_block)
		           > le32_to_cpu(nearex->ee_block)) {
/*		BUG_ON(newext->ee_block == nearex->ee_block); */
		if (nearex != EXT_LAST_EXTENT(eh)) {
			len = EXT_MAX_EXTENT(eh) - nearex;
			len = (len - 1) * sizeof(struct ext4_extent);
			len = len < 0 ? 0 : len;
			ext_debug("insert %d:%llu:%d after: nearest 0x%p, "
					"move %d from 0x%p to 0x%p\n",
				        le32_to_cpu(newext->ee_block),
				        ext_pblock(newext),
				        le16_to_cpu(newext->ee_len),
					nearex, len, nearex + 1, nearex + 2);
			memmove(nearex + 2, nearex + 1, len);
		}
		path[depth].p_ext = nearex + 1;
	} else {
		BUG_ON(newext->ee_block == nearex->ee_block);
		len = (EXT_MAX_EXTENT(eh) - nearex) * sizeof(struct ext4_extent);
		len = len < 0 ? 0 : len;
		ext_debug("insert %d:%llu:%d before: nearest 0x%p, "
				"move %d from 0x%p to 0x%p\n",
				le32_to_cpu(newext->ee_block),
				ext_pblock(newext),
				le16_to_cpu(newext->ee_len),
				nearex, len, nearex + 1, nearex + 2);
		memmove(nearex + 1, nearex, len);
		path[depth].p_ext = nearex;
	}

	eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)+1);
	nearex = path[depth].p_ext;
	nearex->ee_block = newext->ee_block;
	nearex->ee_start = newext->ee_start;
	nearex->ee_start_hi = newext->ee_start_hi;
	nearex->ee_len = newext->ee_len;

merge:
	/* try to merge extents to the right */
	while (nearex < EXT_LAST_EXTENT(eh)) {
		if (!ext4_can_extents_be_merged(inode, nearex, nearex + 1))
			break;
		/* merge with next extent! */
		nearex->ee_len = cpu_to_le16(le16_to_cpu(nearex->ee_len)
					     + le16_to_cpu(nearex[1].ee_len));
		if (nearex + 1 < EXT_LAST_EXTENT(eh)) {
			len = (EXT_LAST_EXTENT(eh) - nearex - 1)
					* sizeof(struct ext4_extent);
			memmove(nearex + 1, nearex + 2, len);
		}
		eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
		BUG_ON(eh->eh_entries == 0);
	}

	/* try to merge extents to the left */

	/* time to correct all indexes above */
	err = ext4_ext_correct_indexes(handle, inode, path);
	if (err)
		goto cleanup;

	err = ext4_ext_dirty(handle, inode, path + depth);

cleanup:
	if (npath) {
		ext4_ext_drop_refs(npath);
		kfree(npath);
	}
	ext4_ext_tree_changed(inode);
	ext4_ext_invalidate_cache(inode);
	return err;
}

int ext4_ext_walk_space(struct inode *inode, unsigned long block,
			unsigned long num, ext_prepare_callback func,
			void *cbdata)
{
	struct ext4_ext_path *path = NULL;
	struct ext4_ext_cache cbex;
	struct ext4_extent *ex;
	unsigned long next, start = 0, end = 0;
	unsigned long last = block + num;
	int depth, exists, err = 0;

	BUG_ON(func == NULL);
	BUG_ON(inode == NULL);

	while (block < last && block != EXT_MAX_BLOCK) {
		num = last - block;
		/* find extent for this block */
		path = ext4_ext_find_extent(inode, block, path);
		if (IS_ERR(path)) {
			err = PTR_ERR(path);
			path = NULL;
			break;
		}

		depth = ext_depth(inode);
		BUG_ON(path[depth].p_hdr == NULL);
		ex = path[depth].p_ext;
		next = ext4_ext_next_allocated_block(path);

		exists = 0;
		if (!ex) {
			/* there is no extent yet, so try to allocate
			 * all requested space */
			start = block;
			end = block + num;
		} else if (le32_to_cpu(ex->ee_block) > block) {
			/* need to allocate space before found extent */
			start = block;
			end = le32_to_cpu(ex->ee_block);
			if (block + num < end)
				end = block + num;
		} else if (block >=
			     le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len)) {
			/* need to allocate space after found extent */
			start = block;
			end = block + num;
			if (end >= next)
				end = next;
		} else if (block >= le32_to_cpu(ex->ee_block)) {
			/*
			 * some part of requested space is covered
			 * by found extent
			 */
			start = block;
			end = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len);
			if (block + num < end)
				end = block + num;
			exists = 1;
		} else {
			BUG();
		}
		BUG_ON(end <= start);

		if (!exists) {
			cbex.ec_block = start;
			cbex.ec_len = end - start;
			cbex.ec_start = 0;
			cbex.ec_type = EXT4_EXT_CACHE_GAP;
		} else {
		        cbex.ec_block = le32_to_cpu(ex->ee_block);
		        cbex.ec_len = le16_to_cpu(ex->ee_len);
		        cbex.ec_start = ext_pblock(ex);
			cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
		}

		BUG_ON(cbex.ec_len == 0);
		err = func(inode, path, &cbex, cbdata);
		ext4_ext_drop_refs(path);

		if (err < 0)
			break;
		if (err == EXT_REPEAT)
			continue;
		else if (err == EXT_BREAK) {
			err = 0;
			break;
		}

		if (ext_depth(inode) != depth) {
			/* depth was changed. we have to realloc path */
			kfree(path);
			path = NULL;
		}

		block = cbex.ec_block + cbex.ec_len;
	}

	if (path) {
		ext4_ext_drop_refs(path);
		kfree(path);
	}

	return err;
}

static void
ext4_ext_put_in_cache(struct inode *inode, __u32 block,
			__u32 len, __u32 start, int type)
{
	struct ext4_ext_cache *cex;
	BUG_ON(len == 0);
	cex = &EXT4_I(inode)->i_cached_extent;
	cex->ec_type = type;
	cex->ec_block = block;
	cex->ec_len = len;
	cex->ec_start = start;
}

/*
 * ext4_ext_put_gap_in_cache:
 * calculate boundaries of the gap that the requested block fits into
 * and cache this gap
 */
static void
ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
				unsigned long block)
{
	int depth = ext_depth(inode);
	unsigned long lblock, len;
	struct ext4_extent *ex;

	ex = path[depth].p_ext;
	if (ex == NULL) {
		/* there is no extent yet, so gap is [0;-] */
		lblock = 0;
		len = EXT_MAX_BLOCK;
		ext_debug("cache gap(whole file):");
	} else if (block < le32_to_cpu(ex->ee_block)) {
		lblock = block;
		len = le32_to_cpu(ex->ee_block) - block;
		ext_debug("cache gap(before): %lu [%lu:%lu]",
				(unsigned long) block,
			        (unsigned long) le32_to_cpu(ex->ee_block),
			        (unsigned long) le16_to_cpu(ex->ee_len));
	} else if (block >= le32_to_cpu(ex->ee_block)
		            + le16_to_cpu(ex->ee_len)) {
	        lblock = le32_to_cpu(ex->ee_block)
		         + le16_to_cpu(ex->ee_len);
		len = ext4_ext_next_allocated_block(path);
		ext_debug("cache gap(after): [%lu:%lu] %lu",
			        (unsigned long) le32_to_cpu(ex->ee_block),
			        (unsigned long) le16_to_cpu(ex->ee_len),
				(unsigned long) block);
		BUG_ON(len == lblock);
		len = len - lblock;
	} else {
		lblock = len = 0;
		BUG();
	}

	ext_debug(" -> %lu:%lu\n", (unsigned long) lblock, len);
	ext4_ext_put_in_cache(inode, lblock, len, 0, EXT4_EXT_CACHE_GAP);
}

static int
ext4_ext_in_cache(struct inode *inode, unsigned long block,
			struct ext4_extent *ex)
{
	struct ext4_ext_cache *cex;

	cex = &EXT4_I(inode)->i_cached_extent;

	/* has cache valid data? */
	if (cex->ec_type == EXT4_EXT_CACHE_NO)
		return EXT4_EXT_CACHE_NO;

	BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP &&
			cex->ec_type != EXT4_EXT_CACHE_EXTENT);
	if (block >= cex->ec_block && block < cex->ec_block + cex->ec_len) {
	        ex->ee_block = cpu_to_le32(cex->ec_block);
		ext4_ext_store_pblock(ex, cex->ec_start);
	        ex->ee_len = cpu_to_le16(cex->ec_len);
		ext_debug("%lu cached by %lu:%lu:%llu\n",
				(unsigned long) block,
				(unsigned long) cex->ec_block,
				(unsigned long) cex->ec_len,
				cex->ec_start);
		return cex->ec_type;
	}

	/* not in cache */
	return EXT4_EXT_CACHE_NO;
}

/*
 * ext4_ext_rm_idx:
 * removes index from the index block.
 * It's used in truncate case only, thus all requests are for
 * last index in the block only.
 */
int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
			struct ext4_ext_path *path)
{
	struct buffer_head *bh;
	int err;
	ext4_fsblk_t leaf;

	/* free index block */
	path--;
	leaf = idx_pblock(path->p_idx);
	BUG_ON(path->p_hdr->eh_entries == 0);
	err = ext4_ext_get_access(handle, inode, path);
	if (err)
		return err;
	path->p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(path->p_hdr->eh_entries)-1);
	err = ext4_ext_dirty(handle, inode, path);
	if (err)
		return err;
	ext_debug("index is empty, remove it, free block %llu\n", leaf);
	bh = sb_find_get_block(inode->i_sb, leaf);
	ext4_forget(handle, 1, inode, bh, leaf);
	ext4_free_blocks(handle, inode, leaf, 1);
	return err;
}

/*
 * ext4_ext_calc_credits_for_insert:
 * This routine returns max. credits that the extent tree can consume.
 * It should be OK for low-performance paths like ->writepage()
 * To allow many writing processes to fit into a single transaction,
 * the caller should calculate credits under truncate_mutex and
 * pass the actual path.
 */
int ext4_ext_calc_credits_for_insert(struct inode *inode,
						struct ext4_ext_path *path)
{
	int depth, needed;

	if (path) {
		/* probably there is space in leaf? */
		depth = ext_depth(inode);
		if (le16_to_cpu(path[depth].p_hdr->eh_entries)
				< le16_to_cpu(path[depth].p_hdr->eh_max))
			return 1;
	}

	/*
	 * given 32-bit logical block (4294967296 blocks), max. tree
	 * can be 4 levels in depth -- 4 * 340^4 == 53453440000.
	 * Let's also add one more level for imbalance.
	 */
	depth = 5;

	/* allocation of new data block(s) */
	needed = 2;

	/*
	 * tree can be full, so it would need to grow in depth:
	 * we need one credit to modify old root, credits for
	 * new root will be added in split accounting
	 */
	needed += 1;

	/*
	 * Index split can happen, we would need:
	 *    allocate intermediate indexes (bitmap + group)
	 *  + change two blocks at each level, but root (already included)
	 */
	needed += (depth * 2) + (depth * 2);

	/* any allocation modifies superblock */
	needed += 1;

	return needed;
}

static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
				struct ext4_extent *ex,
				unsigned long from, unsigned long to)
{
	struct buffer_head *bh;
	int i;

#ifdef EXTENTS_STATS
	{
		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
		unsigned short ee_len =  le16_to_cpu(ex->ee_len);
		spin_lock(&sbi->s_ext_stats_lock);
		sbi->s_ext_blocks += ee_len;
		sbi->s_ext_extents++;
		if (ee_len < sbi->s_ext_min)
			sbi->s_ext_min = ee_len;
		if (ee_len > sbi->s_ext_max)
			sbi->s_ext_max = ee_len;
		if (ext_depth(inode) > sbi->s_depth_max)
			sbi->s_depth_max = ext_depth(inode);
		spin_unlock(&sbi->s_ext_stats_lock);
	}
#endif
	if (from >= le32_to_cpu(ex->ee_block)
	    && to == le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
		/* tail removal */
		unsigned long num;
		ext4_fsblk_t start;
		num = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - from;
		start = ext_pblock(ex) + le16_to_cpu(ex->ee_len) - num;
		ext_debug("free last %lu blocks starting %llu\n", num, start);
		for (i = 0; i < num; i++) {
			bh = sb_find_get_block(inode->i_sb, start + i);
			ext4_forget(handle, 0, inode, bh, start + i);
		}
		ext4_free_blocks(handle, inode, start, num);
	} else if (from == le32_to_cpu(ex->ee_block)
		   && to <= le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
		printk("strange request: removal %lu-%lu from %u:%u\n",
		       from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
	} else {
		printk("strange request: removal(2) %lu-%lu from %u:%u\n",
		       from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
	}
	return 0;
}

static int
ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
		struct ext4_ext_path *path, unsigned long start)
{
	int err = 0, correct_index = 0;
	int depth = ext_depth(inode), credits;
	struct ext4_extent_header *eh;
	unsigned a, b, block, num;
	unsigned long ex_ee_block;
	unsigned short ex_ee_len;
	struct ext4_extent *ex;

	ext_debug("truncate since %lu in leaf\n", start);
	if (!path[depth].p_hdr)
		path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
	eh = path[depth].p_hdr;
	BUG_ON(eh == NULL);
	BUG_ON(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max));
	BUG_ON(eh->eh_magic != EXT4_EXT_MAGIC);

	/* find where to start removing */
	ex = EXT_LAST_EXTENT(eh);

	ex_ee_block = le32_to_cpu(ex->ee_block);
	ex_ee_len = le16_to_cpu(ex->ee_len);

	while (ex >= EXT_FIRST_EXTENT(eh) &&
			ex_ee_block + ex_ee_len > start) {
		ext_debug("remove ext %lu:%u\n", ex_ee_block, ex_ee_len);
		path[depth].p_ext = ex;

		a = ex_ee_block > start ? ex_ee_block : start;
		b = ex_ee_block + ex_ee_len - 1 < EXT_MAX_BLOCK ?
			ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCK;

		ext_debug("  border %u:%u\n", a, b);

		if (a != ex_ee_block && b != ex_ee_block + ex_ee_len - 1) {
			block = 0;
			num = 0;
			BUG();
		} else if (a != ex_ee_block) {
			/* remove tail of the extent */
			block = ex_ee_block;
			num = a - block;
		} else if (b != ex_ee_block + ex_ee_len - 1) {
			/* remove head of the extent */
			block = a;
			num = b - a;
			/* there is no "make a hole" API yet */
			BUG();
		} else {
			/* remove whole extent: excellent! */
			block = ex_ee_block;
			num = 0;
			BUG_ON(a != ex_ee_block);
			BUG_ON(b != ex_ee_block + ex_ee_len - 1);
		}

		/* at present, extent can't cross block group: */
		/* leaf + bitmap + group desc + sb + inode */
		credits = 5;
		if (ex == EXT_FIRST_EXTENT(eh)) {
			correct_index = 1;
			credits += (ext_depth(inode)) + 1;
		}
#ifdef CONFIG_QUOTA
		credits += 2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
#endif

		handle = ext4_ext_journal_restart(handle, credits);
		if (IS_ERR(handle)) {
			err = PTR_ERR(handle);
			goto out;
		}

		err = ext4_ext_get_access(handle, inode, path + depth);
		if (err)
			goto out;

		err = ext4_remove_blocks(handle, inode, ex, a, b);
		if (err)
			goto out;

		if (num == 0) {
			/* this extent is removed; mark slot entirely unused */
			ext4_ext_store_pblock(ex, 0);
			eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
		}

		ex->ee_block = cpu_to_le32(block);
		ex->ee_len = cpu_to_le16(num);

		err = ext4_ext_dirty(handle, inode, path + depth);
		if (err)
			goto out;

		ext_debug("new extent: %u:%u:%llu\n", block, num,
				ext_pblock(ex));
		ex--;
		ex_ee_block = le32_to_cpu(ex->ee_block);
		ex_ee_len = le16_to_cpu(ex->ee_len);
	}

	if (correct_index && eh->eh_entries)
		err = ext4_ext_correct_indexes(handle, inode, path);

	/* if this leaf is free, then we should
	 * remove it from index block above */
	if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
		err = ext4_ext_rm_idx(handle, inode, path + depth);

out:
	return err;
}

/*
 * ext4_ext_more_to_rm:
 * returns 1 if current index has to be freed (even partial)
 */
static int
ext4_ext_more_to_rm(struct ext4_ext_path *path)
{
	BUG_ON(path->p_idx == NULL);

	if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
		return 0;

	/*
	 * if truncate on deeper level happened, it wasn't partial,
	 * so we have to consider current index for truncation
	 */
	if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
		return 0;
	return 1;
}

int ext4_ext_remove_space(struct inode *inode, unsigned long start)
{
	struct super_block *sb = inode->i_sb;
	int depth = ext_depth(inode);
	struct ext4_ext_path *path;
	handle_t *handle;
	int i = 0, err = 0;

	ext_debug("truncate since %lu\n", start);

	/* probably first extent we're gonna free will be last in block */
	handle = ext4_journal_start(inode, depth + 1);
	if (IS_ERR(handle))
		return PTR_ERR(handle);

	ext4_ext_invalidate_cache(inode);

	/*
	 * We start scanning from right side, freeing all the blocks
	 * after i_size and walking into the tree depth-wise.
	 */
	path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_KERNEL);
	if (path == NULL) {
		ext4_journal_stop(handle);
		return -ENOMEM;
	}
	path[0].p_hdr = ext_inode_hdr(inode);
	if (ext4_ext_check_header(__FUNCTION__, inode, path[0].p_hdr)) {
		err = -EIO;
		goto out;
	}
	path[0].p_depth = depth;

	while (i >= 0 && err == 0) {
		if (i == depth) {
			/* this is leaf block */
			err = ext4_ext_rm_leaf(handle, inode, path, start);
			/* root level has p_bh == NULL, brelse() eats this */
			brelse(path[i].p_bh);
			path[i].p_bh = NULL;
			i--;
			continue;
		}

		/* this is index block */
		if (!path[i].p_hdr) {
			ext_debug("initialize header\n");
			path[i].p_hdr = ext_block_hdr(path[i].p_bh);
			if (ext4_ext_check_header(__FUNCTION__, inode,
							path[i].p_hdr)) {
				err = -EIO;
				goto out;
			}
		}

		BUG_ON(le16_to_cpu(path[i].p_hdr->eh_entries)
			   > le16_to_cpu(path[i].p_hdr->eh_max));
		BUG_ON(path[i].p_hdr->eh_magic != EXT4_EXT_MAGIC);

		if (!path[i].p_idx) {
			/* this level hasn't been touched yet */
			path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
			ext_debug("init index ptr: hdr 0x%p, num %d\n",
				  path[i].p_hdr,
				  le16_to_cpu(path[i].p_hdr->eh_entries));
		} else {
			/* we were already here, see at next index */
			path[i].p_idx--;
		}

		ext_debug("level %d - index, first 0x%p, cur 0x%p\n",
				i, EXT_FIRST_INDEX(path[i].p_hdr),
				path[i].p_idx);
		if (ext4_ext_more_to_rm(path + i)) {
			/* go to the next level */
			ext_debug("move to level %d (block %llu)\n",
				  i + 1, idx_pblock(path[i].p_idx));
			memset(path + i + 1, 0, sizeof(*path));
			path[i+1].p_bh =
				sb_bread(sb, idx_pblock(path[i].p_idx));
			if (!path[i+1].p_bh) {
				/* should we reset i_size? */
				err = -EIO;
				break;
			}

			/* save actual number of indexes since this
			 * number is changed at the next iteration */
			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
			i++;
		} else {
			/* we finished processing this index, go up */
			if (path[i].p_hdr->eh_entries == 0 && i > 0) {
				/* index is empty, remove it;
				 * handle must be already prepared by the
				 * truncatei_leaf() */
				err = ext4_ext_rm_idx(handle, inode, path + i);
			}
			/* root level has p_bh == NULL, brelse() eats this */
			brelse(path[i].p_bh);
			path[i].p_bh = NULL;
			i--;
			ext_debug("return to level %d\n", i);
		}
	}

	/* TODO: flexible tree reduction should be here */
	if (path->p_hdr->eh_entries == 0) {
		/*
		 * truncate to zero freed all the tree,
		 * so we need to correct eh_depth
		 */
		err = ext4_ext_get_access(handle, inode, path);
		if (err == 0) {
			ext_inode_hdr(inode)->eh_depth = 0;
			ext_inode_hdr(inode)->eh_max =
				cpu_to_le16(ext4_ext_space_root(inode));
			err = ext4_ext_dirty(handle, inode, path);
		}
	}
out:
	ext4_ext_tree_changed(inode);
	ext4_ext_drop_refs(path);
	kfree(path);
	ext4_journal_stop(handle);

	return err;
}

/*
 * called at mount time
 */
void ext4_ext_init(struct super_block *sb)
{
	/*
	 * possible initialization would be here
	 */

	if (test_opt(sb, EXTENTS)) {
		printk("EXT4-fs: file extents enabled");
#ifdef AGRESSIVE_TEST
		printk(", agressive tests");
#endif
#ifdef CHECK_BINSEARCH
		printk(", check binsearch");
#endif
#ifdef EXTENTS_STATS
		printk(", stats");
#endif
		printk("\n");
#ifdef EXTENTS_STATS
		spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
		EXT4_SB(sb)->s_ext_min = 1 << 30;
		EXT4_SB(sb)->s_ext_max = 0;
#endif
	}
}

/*
 * called at umount time
 */
void ext4_ext_release(struct super_block *sb)
{
	if (!test_opt(sb, EXTENTS))
		return;

#ifdef EXTENTS_STATS
	if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
		struct ext4_sb_info *sbi = EXT4_SB(sb);
		printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
			sbi->s_ext_blocks, sbi->s_ext_extents,
			sbi->s_ext_blocks / sbi->s_ext_extents);
		printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
			sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
	}
#endif
}

int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
			ext4_fsblk_t iblock,
			unsigned long max_blocks, struct buffer_head *bh_result,
			int create, int extend_disksize)
{
	struct ext4_ext_path *path = NULL;
	struct ext4_extent newex, *ex;
	ext4_fsblk_t goal, newblock;
	int err = 0, depth;
	unsigned long allocated = 0;

	__clear_bit(BH_New, &bh_result->b_state);
	ext_debug("blocks %d/%lu requested for inode %u\n", (int) iblock,
			max_blocks, (unsigned) inode->i_ino);
	mutex_lock(&EXT4_I(inode)->truncate_mutex);

	/* check in cache */
	goal = ext4_ext_in_cache(inode, iblock, &newex);
	if (goal) {
		if (goal == EXT4_EXT_CACHE_GAP) {
			if (!create) {
				/* block isn't allocated yet and
				 * user doesn't want to allocate it */
				goto out2;
			}
			/* we should allocate requested block */
		} else if (goal == EXT4_EXT_CACHE_EXTENT) {
			/* block is already allocated */
		        newblock = iblock
		                   - le32_to_cpu(newex.ee_block)
			           + ext_pblock(&newex);
			/* number of remaining blocks in the extent */
			allocated = le16_to_cpu(newex.ee_len) -
					(iblock - le32_to_cpu(newex.ee_block));
			goto out;
		} else {
			BUG();
		}
	}

	/* find extent for this block */
	path = ext4_ext_find_extent(inode, iblock, NULL);
	if (IS_ERR(path)) {
		err = PTR_ERR(path);
		path = NULL;
		goto out2;
	}

	depth = ext_depth(inode);

	/*
	 * consistent leaf must not be empty;
	 * this situation is possible, though, _during_ tree modification;
	 * this is why assert can't be put in ext4_ext_find_extent()
	 */
	BUG_ON(path[depth].p_ext == NULL && depth != 0);

	ex = path[depth].p_ext;
	if (ex) {
	        unsigned long ee_block = le32_to_cpu(ex->ee_block);
		ext4_fsblk_t ee_start = ext_pblock(ex);
		unsigned short ee_len  = le16_to_cpu(ex->ee_len);

		/*
		 * Allow future support for preallocated extents to be added
		 * as an RO_COMPAT feature:
		 * Uninitialized extents are treated as holes, except that
		 * we avoid (fail) allocating new blocks during a write.
		 */
		if (ee_len > EXT_MAX_LEN)
			goto out2;
		/* if found extent covers block, simply return it */
	        if (iblock >= ee_block && iblock < ee_block + ee_len) {
			newblock = iblock - ee_block + ee_start;
			/* number of remaining blocks in the extent */
			allocated = ee_len - (iblock - ee_block);
			ext_debug("%d fit into %lu:%d -> %llu\n", (int) iblock,
					ee_block, ee_len, newblock);
			ext4_ext_put_in_cache(inode, ee_block, ee_len,
						ee_start, EXT4_EXT_CACHE_EXTENT);
			goto out;
		}
	}

	/*
	 * requested block isn't allocated yet;
	 * we couldn't try to create block if create flag is zero
	 */
	if (!create) {
		/* put just found gap into cache to speed up
		 * subsequent requests */
		ext4_ext_put_gap_in_cache(inode, path, iblock);
		goto out2;
	}
	/*
	 * Okay, we need to do block allocation.  Lazily initialize the block
	 * allocation info here if necessary.
	 */
	if (S_ISREG(inode->i_mode) && (!EXT4_I(inode)->i_block_alloc_info))
		ext4_init_block_alloc_info(inode);

	/* allocate new block */
	goal = ext4_ext_find_goal(inode, path, iblock);
	allocated = max_blocks;
	newblock = ext4_new_blocks(handle, inode, goal, &allocated, &err);
	if (!newblock)
		goto out2;
	ext_debug("allocate new block: goal %llu, found %llu/%lu\n",
			goal, newblock, allocated);

	/* try to insert new extent into found leaf and return */
	newex.ee_block = cpu_to_le32(iblock);
	ext4_ext_store_pblock(&newex, newblock);
	newex.ee_len = cpu_to_le16(allocated);
	err = ext4_ext_insert_extent(handle, inode, path, &newex);
	if (err)
		goto out2;

	if (extend_disksize && inode->i_size > EXT4_I(inode)->i_disksize)
		EXT4_I(inode)->i_disksize = inode->i_size;

	/* previous routine could use block we allocated */
	newblock = ext_pblock(&newex);
	__set_bit(BH_New, &bh_result->b_state);

	ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
				EXT4_EXT_CACHE_EXTENT);
out:
	if (allocated > max_blocks)
		allocated = max_blocks;
	ext4_ext_show_leaf(inode, path);
	__set_bit(BH_Mapped, &bh_result->b_state);
	bh_result->b_bdev = inode->i_sb->s_bdev;
	bh_result->b_blocknr = newblock;
out2:
	if (path) {
		ext4_ext_drop_refs(path);
		kfree(path);
	}
	mutex_unlock(&EXT4_I(inode)->truncate_mutex);

	return err ? err : allocated;
}

void ext4_ext_truncate(struct inode * inode, struct page *page)
{
	struct address_space *mapping = inode->i_mapping;
	struct super_block *sb = inode->i_sb;
	unsigned long last_block;
	handle_t *handle;
	int err = 0;

	/*
	 * probably first extent we're gonna free will be last in block
	 */
	err = ext4_writepage_trans_blocks(inode) + 3;
	handle = ext4_journal_start(inode, err);
	if (IS_ERR(handle)) {
		if (page) {
			clear_highpage(page);
			flush_dcache_page(page);
			unlock_page(page);
			page_cache_release(page);
		}
		return;
	}

	if (page)
		ext4_block_truncate_page(handle, page, mapping, inode->i_size);

	mutex_lock(&EXT4_I(inode)->truncate_mutex);
	ext4_ext_invalidate_cache(inode);

	/*
	 * TODO: optimization is possible here.
	 * Probably we need not scan at all,
	 * because page truncation is enough.
	 */
	if (ext4_orphan_add(handle, inode))
		goto out_stop;

	/* we have to know where to truncate from in crash case */
	EXT4_I(inode)->i_disksize = inode->i_size;
	ext4_mark_inode_dirty(handle, inode);

	last_block = (inode->i_size + sb->s_blocksize - 1)
			>> EXT4_BLOCK_SIZE_BITS(sb);
	err = ext4_ext_remove_space(inode, last_block);

	/* In a multi-transaction truncate, we only make the final
	 * transaction synchronous. */
	if (IS_SYNC(inode))
		handle->h_sync = 1;

out_stop:
	/*
	 * If this was a simple ftruncate() and the file will remain alive,
	 * then we need to clear up the orphan record which we created above.
	 * However, if this was a real unlink then we were called by
	 * ext4_delete_inode(), and we allow that function to clean up the
	 * orphan info for us.
	 */
	if (inode->i_nlink)
		ext4_orphan_del(handle, inode);

	mutex_unlock(&EXT4_I(inode)->truncate_mutex);
	ext4_journal_stop(handle);
}

/*
 * ext4_ext_writepage_trans_blocks:
 * calculate max number of blocks we could modify
 * in order to allocate new block for an inode
 */
int ext4_ext_writepage_trans_blocks(struct inode *inode, int num)
{
	int needed;

	needed = ext4_ext_calc_credits_for_insert(inode, NULL);

	/* caller wants to allocate num blocks, but note it includes sb */
	needed = needed * num - (num - 1);

#ifdef CONFIG_QUOTA
	needed += 2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
#endif

	return needed;
}

EXPORT_SYMBOL(ext4_mark_inode_dirty);
EXPORT_SYMBOL(ext4_ext_invalidate_cache);
EXPORT_SYMBOL(ext4_ext_insert_extent);
EXPORT_SYMBOL(ext4_ext_walk_space);
EXPORT_SYMBOL(ext4_ext_find_goal);
EXPORT_SYMBOL(ext4_ext_calc_credits_for_insert);

OpenPOWER on IntegriCloud