summaryrefslogtreecommitdiff
path: root/fs/ext4/extents_status.c
blob: 7521de2dcf3aebd710af8da53bdcc18798f0f522 (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
// SPDX-License-Identifier: GPL-2.0
/*
 *  fs/ext4/extents_status.c
 *
 * Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
 * Modified by
 *	Allison Henderson <achender@linux.vnet.ibm.com>
 *	Hugh Dickins <hughd@google.com>
 *	Zheng Liu <wenqing.lz@taobao.com>
 *
 * Ext4 extents status tree core functions.
 */
#include <linux/list_sort.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "ext4.h"

#include <trace/events/ext4.h>

/*
 * According to previous discussion in Ext4 Developer Workshop, we
 * will introduce a new structure called io tree to track all extent
 * status in order to solve some problems that we have met
 * (e.g. Reservation space warning), and provide extent-level locking.
 * Delay extent tree is the first step to achieve this goal.  It is
 * original built by Yongqiang Yang.  At that time it is called delay
 * extent tree, whose goal is only track delayed extents in memory to
 * simplify the implementation of fiemap and bigalloc, and introduce
 * lseek SEEK_DATA/SEEK_HOLE support.  That is why it is still called
 * delay extent tree at the first commit.  But for better understand
 * what it does, it has been rename to extent status tree.
 *
 * Step1:
 * Currently the first step has been done.  All delayed extents are
 * tracked in the tree.  It maintains the delayed extent when a delayed
 * allocation is issued, and the delayed extent is written out or
 * invalidated.  Therefore the implementation of fiemap and bigalloc
 * are simplified, and SEEK_DATA/SEEK_HOLE are introduced.
 *
 * The following comment describes the implemenmtation of extent
 * status tree and future works.
 *
 * Step2:
 * In this step all extent status are tracked by extent status tree.
 * Thus, we can first try to lookup a block mapping in this tree before
 * finding it in extent tree.  Hence, single extent cache can be removed
 * because extent status tree can do a better job.  Extents in status
 * tree are loaded on-demand.  Therefore, the extent status tree may not
 * contain all of the extents in a file.  Meanwhile we define a shrinker
 * to reclaim memory from extent status tree because fragmented extent
 * tree will make status tree cost too much memory.  written/unwritten/-
 * hole extents in the tree will be reclaimed by this shrinker when we
 * are under high memory pressure.  Delayed extents will not be
 * reclimed because fiemap, bigalloc, and seek_data/hole need it.
 */

/*
 * Extent status tree implementation for ext4.
 *
 *
 * ==========================================================================
 * Extent status tree tracks all extent status.
 *
 * 1. Why we need to implement extent status tree?
 *
 * Without extent status tree, ext4 identifies a delayed extent by looking
 * up page cache, this has several deficiencies - complicated, buggy,
 * and inefficient code.
 *
 * FIEMAP, SEEK_HOLE/DATA, bigalloc, and writeout all need to know if a
 * block or a range of blocks are belonged to a delayed extent.
 *
 * Let us have a look at how they do without extent status tree.
 *   --	FIEMAP
 *	FIEMAP looks up page cache to identify delayed allocations from holes.
 *
 *   --	SEEK_HOLE/DATA
 *	SEEK_HOLE/DATA has the same problem as FIEMAP.
 *
 *   --	bigalloc
 *	bigalloc looks up page cache to figure out if a block is
 *	already under delayed allocation or not to determine whether
 *	quota reserving is needed for the cluster.
 *
 *   --	writeout
 *	Writeout looks up whole page cache to see if a buffer is
 *	mapped, If there are not very many delayed buffers, then it is
 *	time consuming.
 *
 * With extent status tree implementation, FIEMAP, SEEK_HOLE/DATA,
 * bigalloc and writeout can figure out if a block or a range of
 * blocks is under delayed allocation(belonged to a delayed extent) or
 * not by searching the extent tree.
 *
 *
 * ==========================================================================
 * 2. Ext4 extent status tree impelmentation
 *
 *   --	extent
 *	A extent is a range of blocks which are contiguous logically and
 *	physically.  Unlike extent in extent tree, this extent in ext4 is
 *	a in-memory struct, there is no corresponding on-disk data.  There
 *	is no limit on length of extent, so an extent can contain as many
 *	blocks as they are contiguous logically and physically.
 *
 *   --	extent status tree
 *	Every inode has an extent status tree and all allocation blocks
 *	are added to the tree with different status.  The extent in the
 *	tree are ordered by logical block no.
 *
 *   --	operations on a extent status tree
 *	There are three important operations on a delayed extent tree: find
 *	next extent, adding a extent(a range of blocks) and removing a extent.
 *
 *   --	race on a extent status tree
 *	Extent status tree is protected by inode->i_es_lock.
 *
 *   --	memory consumption
 *      Fragmented extent tree will make extent status tree cost too much
 *      memory.  Hence, we will reclaim written/unwritten/hole extents from
 *      the tree under a heavy memory pressure.
 *
 *
 * ==========================================================================
 * 3. Performance analysis
 *
 *   --	overhead
 *	1. There is a cache extent for write access, so if writes are
 *	not very random, adding space operaions are in O(1) time.
 *
 *   --	gain
 *	2. Code is much simpler, more readable, more maintainable and
 *	more efficient.
 *
 *
 * ==========================================================================
 * 4. TODO list
 *
 *   -- Refactor delayed space reservation
 *
 *   -- Extent-level locking
 */

static struct kmem_cache *ext4_es_cachep;
static struct kmem_cache *ext4_pending_cachep;

static int __es_insert_extent(struct inode *inode, struct extent_status *newes);
static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
			      ext4_lblk_t end);
static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan);
static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
		       struct ext4_inode_info *locked_ei);
static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
			     ext4_lblk_t len);

int __init ext4_init_es(void)
{
	ext4_es_cachep = kmem_cache_create("ext4_extent_status",
					   sizeof(struct extent_status),
					   0, (SLAB_RECLAIM_ACCOUNT), NULL);
	if (ext4_es_cachep == NULL)
		return -ENOMEM;
	return 0;
}

void ext4_exit_es(void)
{
	kmem_cache_destroy(ext4_es_cachep);
}

void ext4_es_init_tree(struct ext4_es_tree *tree)
{
	tree->root = RB_ROOT;
	tree->cache_es = NULL;
}

#ifdef ES_DEBUG__
static void ext4_es_print_tree(struct inode *inode)
{
	struct ext4_es_tree *tree;
	struct rb_node *node;

	printk(KERN_DEBUG "status extents for inode %lu:", inode->i_ino);
	tree = &EXT4_I(inode)->i_es_tree;
	node = rb_first(&tree->root);
	while (node) {
		struct extent_status *es;
		es = rb_entry(node, struct extent_status, rb_node);
		printk(KERN_DEBUG " [%u/%u) %llu %x",
		       es->es_lblk, es->es_len,
		       ext4_es_pblock(es), ext4_es_status(es));
		node = rb_next(node);
	}
	printk(KERN_DEBUG "\n");
}
#else
#define ext4_es_print_tree(inode)
#endif

static inline ext4_lblk_t ext4_es_end(struct extent_status *es)
{
	BUG_ON(es->es_lblk + es->es_len < es->es_lblk);
	return es->es_lblk + es->es_len - 1;
}

/*
 * search through the tree for an delayed extent with a given offset.  If
 * it can't be found, try to find next extent.
 */
static struct extent_status *__es_tree_search(struct rb_root *root,
					      ext4_lblk_t lblk)
{
	struct rb_node *node = root->rb_node;
	struct extent_status *es = NULL;

	while (node) {
		es = rb_entry(node, struct extent_status, rb_node);
		if (lblk < es->es_lblk)
			node = node->rb_left;
		else if (lblk > ext4_es_end(es))
			node = node->rb_right;
		else
			return es;
	}

	if (es && lblk < es->es_lblk)
		return es;

	if (es && lblk > ext4_es_end(es)) {
		node = rb_next(&es->rb_node);
		return node ? rb_entry(node, struct extent_status, rb_node) :
			      NULL;
	}

	return NULL;
}

/*
 * ext4_es_find_extent_range - find extent with specified status within block
 *                             range or next extent following block range in
 *                             extents status tree
 *
 * @inode - file containing the range
 * @matching_fn - pointer to function that matches extents with desired status
 * @lblk - logical block defining start of range
 * @end - logical block defining end of range
 * @es - extent found, if any
 *
 * Find the first extent within the block range specified by @lblk and @end
 * in the extents status tree that satisfies @matching_fn.  If a match
 * is found, it's returned in @es.  If not, and a matching extent is found
 * beyond the block range, it's returned in @es.  If no match is found, an
 * extent is returned in @es whose es_lblk, es_len, and es_pblk components
 * are 0.
 */
static void __es_find_extent_range(struct inode *inode,
				   int (*matching_fn)(struct extent_status *es),
				   ext4_lblk_t lblk, ext4_lblk_t end,
				   struct extent_status *es)
{
	struct ext4_es_tree *tree = NULL;
	struct extent_status *es1 = NULL;
	struct rb_node *node;

	WARN_ON(es == NULL);
	WARN_ON(end < lblk);

	tree = &EXT4_I(inode)->i_es_tree;

	/* see if the extent has been cached */
	es->es_lblk = es->es_len = es->es_pblk = 0;
	if (tree->cache_es) {
		es1 = tree->cache_es;
		if (in_range(lblk, es1->es_lblk, es1->es_len)) {
			es_debug("%u cached by [%u/%u) %llu %x\n",
				 lblk, es1->es_lblk, es1->es_len,
				 ext4_es_pblock(es1), ext4_es_status(es1));
			goto out;
		}
	}

	es1 = __es_tree_search(&tree->root, lblk);

out:
	if (es1 && !matching_fn(es1)) {
		while ((node = rb_next(&es1->rb_node)) != NULL) {
			es1 = rb_entry(node, struct extent_status, rb_node);
			if (es1->es_lblk > end) {
				es1 = NULL;
				break;
			}
			if (matching_fn(es1))
				break;
		}
	}

	if (es1 && matching_fn(es1)) {
		tree->cache_es = es1;
		es->es_lblk = es1->es_lblk;
		es->es_len = es1->es_len;
		es->es_pblk = es1->es_pblk;
	}

}

/*
 * Locking for __es_find_extent_range() for external use
 */
void ext4_es_find_extent_range(struct inode *inode,
			       int (*matching_fn)(struct extent_status *es),
			       ext4_lblk_t lblk, ext4_lblk_t end,
			       struct extent_status *es)
{
	trace_ext4_es_find_extent_range_enter(inode, lblk);

	read_lock(&EXT4_I(inode)->i_es_lock);
	__es_find_extent_range(inode, matching_fn, lblk, end, es);
	read_unlock(&EXT4_I(inode)->i_es_lock);

	trace_ext4_es_find_extent_range_exit(inode, es);
}

/*
 * __es_scan_range - search block range for block with specified status
 *                   in extents status tree
 *
 * @inode - file containing the range
 * @matching_fn - pointer to function that matches extents with desired status
 * @lblk - logical block defining start of range
 * @end - logical block defining end of range
 *
 * Returns true if at least one block in the specified block range satisfies
 * the criterion specified by @matching_fn, and false if not.  If at least
 * one extent has the specified status, then there is at least one block
 * in the cluster with that status.  Should only be called by code that has
 * taken i_es_lock.
 */
static bool __es_scan_range(struct inode *inode,
			    int (*matching_fn)(struct extent_status *es),
			    ext4_lblk_t start, ext4_lblk_t end)
{
	struct extent_status es;

	__es_find_extent_range(inode, matching_fn, start, end, &es);
	if (es.es_len == 0)
		return false;   /* no matching extent in the tree */
	else if (es.es_lblk <= start &&
		 start < es.es_lblk + es.es_len)
		return true;
	else if (start <= es.es_lblk && es.es_lblk <= end)
		return true;
	else
		return false;
}
/*
 * Locking for __es_scan_range() for external use
 */
bool ext4_es_scan_range(struct inode *inode,
			int (*matching_fn)(struct extent_status *es),
			ext4_lblk_t lblk, ext4_lblk_t end)
{
	bool ret;

	read_lock(&EXT4_I(inode)->i_es_lock);
	ret = __es_scan_range(inode, matching_fn, lblk, end);
	read_unlock(&EXT4_I(inode)->i_es_lock);

	return ret;
}

/*
 * __es_scan_clu - search cluster for block with specified status in
 *                 extents status tree
 *
 * @inode - file containing the cluster
 * @matching_fn - pointer to function that matches extents with desired status
 * @lblk - logical block in cluster to be searched
 *
 * Returns true if at least one extent in the cluster containing @lblk
 * satisfies the criterion specified by @matching_fn, and false if not.  If at
 * least one extent has the specified status, then there is at least one block
 * in the cluster with that status.  Should only be called by code that has
 * taken i_es_lock.
 */
static bool __es_scan_clu(struct inode *inode,
			  int (*matching_fn)(struct extent_status *es),
			  ext4_lblk_t lblk)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	ext4_lblk_t lblk_start, lblk_end;

	lblk_start = EXT4_LBLK_CMASK(sbi, lblk);
	lblk_end = lblk_start + sbi->s_cluster_ratio - 1;

	return __es_scan_range(inode, matching_fn, lblk_start, lblk_end);
}

/*
 * Locking for __es_scan_clu() for external use
 */
bool ext4_es_scan_clu(struct inode *inode,
		      int (*matching_fn)(struct extent_status *es),
		      ext4_lblk_t lblk)
{
	bool ret;

	read_lock(&EXT4_I(inode)->i_es_lock);
	ret = __es_scan_clu(inode, matching_fn, lblk);
	read_unlock(&EXT4_I(inode)->i_es_lock);

	return ret;
}

static void ext4_es_list_add(struct inode *inode)
{
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

	if (!list_empty(&ei->i_es_list))
		return;

	spin_lock(&sbi->s_es_lock);
	if (list_empty(&ei->i_es_list)) {
		list_add_tail(&ei->i_es_list, &sbi->s_es_list);
		sbi->s_es_nr_inode++;
	}
	spin_unlock(&sbi->s_es_lock);
}

static void ext4_es_list_del(struct inode *inode)
{
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

	spin_lock(&sbi->s_es_lock);
	if (!list_empty(&ei->i_es_list)) {
		list_del_init(&ei->i_es_list);
		sbi->s_es_nr_inode--;
		WARN_ON_ONCE(sbi->s_es_nr_inode < 0);
	}
	spin_unlock(&sbi->s_es_lock);
}

static struct extent_status *
ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
		     ext4_fsblk_t pblk)
{
	struct extent_status *es;
	es = kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC);
	if (es == NULL)
		return NULL;
	es->es_lblk = lblk;
	es->es_len = len;
	es->es_pblk = pblk;

	/*
	 * We don't count delayed extent because we never try to reclaim them
	 */
	if (!ext4_es_is_delayed(es)) {
		if (!EXT4_I(inode)->i_es_shk_nr++)
			ext4_es_list_add(inode);
		percpu_counter_inc(&EXT4_SB(inode->i_sb)->
					s_es_stats.es_stats_shk_cnt);
	}

	EXT4_I(inode)->i_es_all_nr++;
	percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);

	return es;
}

static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
{
	EXT4_I(inode)->i_es_all_nr--;
	percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);

	/* Decrease the shrink counter when this es is not delayed */
	if (!ext4_es_is_delayed(es)) {
		BUG_ON(EXT4_I(inode)->i_es_shk_nr == 0);
		if (!--EXT4_I(inode)->i_es_shk_nr)
			ext4_es_list_del(inode);
		percpu_counter_dec(&EXT4_SB(inode->i_sb)->
					s_es_stats.es_stats_shk_cnt);
	}

	kmem_cache_free(ext4_es_cachep, es);
}

/*
 * Check whether or not two extents can be merged
 * Condition:
 *  - logical block number is contiguous
 *  - physical block number is contiguous
 *  - status is equal
 */
static int ext4_es_can_be_merged(struct extent_status *es1,
				 struct extent_status *es2)
{
	if (ext4_es_type(es1) != ext4_es_type(es2))
		return 0;

	if (((__u64) es1->es_len) + es2->es_len > EXT_MAX_BLOCKS) {
		pr_warn("ES assertion failed when merging extents. "
			"The sum of lengths of es1 (%d) and es2 (%d) "
			"is bigger than allowed file size (%d)\n",
			es1->es_len, es2->es_len, EXT_MAX_BLOCKS);
		WARN_ON(1);
		return 0;
	}

	if (((__u64) es1->es_lblk) + es1->es_len != es2->es_lblk)
		return 0;

	if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) &&
	    (ext4_es_pblock(es1) + es1->es_len == ext4_es_pblock(es2)))
		return 1;

	if (ext4_es_is_hole(es1))
		return 1;

	/* we need to check delayed extent is without unwritten status */
	if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1))
		return 1;

	return 0;
}

static struct extent_status *
ext4_es_try_to_merge_left(struct inode *inode, struct extent_status *es)
{
	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
	struct extent_status *es1;
	struct rb_node *node;

	node = rb_prev(&es->rb_node);
	if (!node)
		return es;

	es1 = rb_entry(node, struct extent_status, rb_node);
	if (ext4_es_can_be_merged(es1, es)) {
		es1->es_len += es->es_len;
		if (ext4_es_is_referenced(es))
			ext4_es_set_referenced(es1);
		rb_erase(&es->rb_node, &tree->root);
		ext4_es_free_extent(inode, es);
		es = es1;
	}

	return es;
}

static struct extent_status *
ext4_es_try_to_merge_right(struct inode *inode, struct extent_status *es)
{
	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
	struct extent_status *es1;
	struct rb_node *node;

	node = rb_next(&es->rb_node);
	if (!node)
		return es;

	es1 = rb_entry(node, struct extent_status, rb_node);
	if (ext4_es_can_be_merged(es, es1)) {
		es->es_len += es1->es_len;
		if (ext4_es_is_referenced(es1))
			ext4_es_set_referenced(es);
		rb_erase(node, &tree->root);
		ext4_es_free_extent(inode, es1);
	}

	return es;
}

#ifdef ES_AGGRESSIVE_TEST
#include "ext4_extents.h"	/* Needed when ES_AGGRESSIVE_TEST is defined */

static void ext4_es_insert_extent_ext_check(struct inode *inode,
					    struct extent_status *es)
{
	struct ext4_ext_path *path = NULL;
	struct ext4_extent *ex;
	ext4_lblk_t ee_block;
	ext4_fsblk_t ee_start;
	unsigned short ee_len;
	int depth, ee_status, es_status;

	path = ext4_find_extent(inode, es->es_lblk, NULL, EXT4_EX_NOCACHE);
	if (IS_ERR(path))
		return;

	depth = ext_depth(inode);
	ex = path[depth].p_ext;

	if (ex) {

		ee_block = le32_to_cpu(ex->ee_block);
		ee_start = ext4_ext_pblock(ex);
		ee_len = ext4_ext_get_actual_len(ex);

		ee_status = ext4_ext_is_unwritten(ex) ? 1 : 0;
		es_status = ext4_es_is_unwritten(es) ? 1 : 0;

		/*
		 * Make sure ex and es are not overlap when we try to insert
		 * a delayed/hole extent.
		 */
		if (!ext4_es_is_written(es) && !ext4_es_is_unwritten(es)) {
			if (in_range(es->es_lblk, ee_block, ee_len)) {
				pr_warn("ES insert assertion failed for "
					"inode: %lu we can find an extent "
					"at block [%d/%d/%llu/%c], but we "
					"want to add a delayed/hole extent "
					"[%d/%d/%llu/%x]\n",
					inode->i_ino, ee_block, ee_len,
					ee_start, ee_status ? 'u' : 'w',
					es->es_lblk, es->es_len,
					ext4_es_pblock(es), ext4_es_status(es));
			}
			goto out;
		}

		/*
		 * We don't check ee_block == es->es_lblk, etc. because es
		 * might be a part of whole extent, vice versa.
		 */
		if (es->es_lblk < ee_block ||
		    ext4_es_pblock(es) != ee_start + es->es_lblk - ee_block) {
			pr_warn("ES insert assertion failed for inode: %lu "
				"ex_status [%d/%d/%llu/%c] != "
				"es_status [%d/%d/%llu/%c]\n", inode->i_ino,
				ee_block, ee_len, ee_start,
				ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
				ext4_es_pblock(es), es_status ? 'u' : 'w');
			goto out;
		}

		if (ee_status ^ es_status) {
			pr_warn("ES insert assertion failed for inode: %lu "
				"ex_status [%d/%d/%llu/%c] != "
				"es_status [%d/%d/%llu/%c]\n", inode->i_ino,
				ee_block, ee_len, ee_start,
				ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
				ext4_es_pblock(es), es_status ? 'u' : 'w');
		}
	} else {
		/*
		 * We can't find an extent on disk.  So we need to make sure
		 * that we don't want to add an written/unwritten extent.
		 */
		if (!ext4_es_is_delayed(es) && !ext4_es_is_hole(es)) {
			pr_warn("ES insert assertion failed for inode: %lu "
				"can't find an extent at block %d but we want "
				"to add a written/unwritten extent "
				"[%d/%d/%llu/%x]\n", inode->i_ino,
				es->es_lblk, es->es_lblk, es->es_len,
				ext4_es_pblock(es), ext4_es_status(es));
		}
	}
out:
	ext4_ext_drop_refs(path);
	kfree(path);
}

static void ext4_es_insert_extent_ind_check(struct inode *inode,
					    struct extent_status *es)
{
	struct ext4_map_blocks map;
	int retval;

	/*
	 * Here we call ext4_ind_map_blocks to lookup a block mapping because
	 * 'Indirect' structure is defined in indirect.c.  So we couldn't
	 * access direct/indirect tree from outside.  It is too dirty to define
	 * this function in indirect.c file.
	 */

	map.m_lblk = es->es_lblk;
	map.m_len = es->es_len;

	retval = ext4_ind_map_blocks(NULL, inode, &map, 0);
	if (retval > 0) {
		if (ext4_es_is_delayed(es) || ext4_es_is_hole(es)) {
			/*
			 * We want to add a delayed/hole extent but this
			 * block has been allocated.
			 */
			pr_warn("ES insert assertion failed for inode: %lu "
				"We can find blocks but we want to add a "
				"delayed/hole extent [%d/%d/%llu/%x]\n",
				inode->i_ino, es->es_lblk, es->es_len,
				ext4_es_pblock(es), ext4_es_status(es));
			return;
		} else if (ext4_es_is_written(es)) {
			if (retval != es->es_len) {
				pr_warn("ES insert assertion failed for "
					"inode: %lu retval %d != es_len %d\n",
					inode->i_ino, retval, es->es_len);
				return;
			}
			if (map.m_pblk != ext4_es_pblock(es)) {
				pr_warn("ES insert assertion failed for "
					"inode: %lu m_pblk %llu != "
					"es_pblk %llu\n",
					inode->i_ino, map.m_pblk,
					ext4_es_pblock(es));
				return;
			}
		} else {
			/*
			 * We don't need to check unwritten extent because
			 * indirect-based file doesn't have it.
			 */
			BUG();
		}
	} else if (retval == 0) {
		if (ext4_es_is_written(es)) {
			pr_warn("ES insert assertion failed for inode: %lu "
				"We can't find the block but we want to add "
				"a written extent [%d/%d/%llu/%x]\n",
				inode->i_ino, es->es_lblk, es->es_len,
				ext4_es_pblock(es), ext4_es_status(es));
			return;
		}
	}
}

static inline void ext4_es_insert_extent_check(struct inode *inode,
					       struct extent_status *es)
{
	/*
	 * We don't need to worry about the race condition because
	 * caller takes i_data_sem locking.
	 */
	BUG_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
		ext4_es_insert_extent_ext_check(inode, es);
	else
		ext4_es_insert_extent_ind_check(inode, es);
}
#else
static inline void ext4_es_insert_extent_check(struct inode *inode,
					       struct extent_status *es)
{
}
#endif

static int __es_insert_extent(struct inode *inode, struct extent_status *newes)
{
	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
	struct rb_node **p = &tree->root.rb_node;
	struct rb_node *parent = NULL;
	struct extent_status *es;

	while (*p) {
		parent = *p;
		es = rb_entry(parent, struct extent_status, rb_node);

		if (newes->es_lblk < es->es_lblk) {
			if (ext4_es_can_be_merged(newes, es)) {
				/*
				 * Here we can modify es_lblk directly
				 * because it isn't overlapped.
				 */
				es->es_lblk = newes->es_lblk;
				es->es_len += newes->es_len;
				if (ext4_es_is_written(es) ||
				    ext4_es_is_unwritten(es))
					ext4_es_store_pblock(es,
							     newes->es_pblk);
				es = ext4_es_try_to_merge_left(inode, es);
				goto out;
			}
			p = &(*p)->rb_left;
		} else if (newes->es_lblk > ext4_es_end(es)) {
			if (ext4_es_can_be_merged(es, newes)) {
				es->es_len += newes->es_len;
				es = ext4_es_try_to_merge_right(inode, es);
				goto out;
			}
			p = &(*p)->rb_right;
		} else {
			BUG();
			return -EINVAL;
		}
	}

	es = ext4_es_alloc_extent(inode, newes->es_lblk, newes->es_len,
				  newes->es_pblk);
	if (!es)
		return -ENOMEM;
	rb_link_node(&es->rb_node, parent, p);
	rb_insert_color(&es->rb_node, &tree->root);

out:
	tree->cache_es = es;
	return 0;
}

/*
 * ext4_es_insert_extent() adds information to an inode's extent
 * status tree.
 *
 * Return 0 on success, error code on failure.
 */
int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
			  ext4_lblk_t len, ext4_fsblk_t pblk,
			  unsigned int status)
{
	struct extent_status newes;
	ext4_lblk_t end = lblk + len - 1;
	int err = 0;
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

	es_debug("add [%u/%u) %llu %x to extent status tree of inode %lu\n",
		 lblk, len, pblk, status, inode->i_ino);

	if (!len)
		return 0;

	BUG_ON(end < lblk);

	if ((status & EXTENT_STATUS_DELAYED) &&
	    (status & EXTENT_STATUS_WRITTEN)) {
		ext4_warning(inode->i_sb, "Inserting extent [%u/%u] as "
				" delayed and written which can potentially "
				" cause data loss.", lblk, len);
		WARN_ON(1);
	}

	newes.es_lblk = lblk;
	newes.es_len = len;
	ext4_es_store_pblock_status(&newes, pblk, status);
	trace_ext4_es_insert_extent(inode, &newes);

	ext4_es_insert_extent_check(inode, &newes);

	write_lock(&EXT4_I(inode)->i_es_lock);
	err = __es_remove_extent(inode, lblk, end);
	if (err != 0)
		goto error;
retry:
	err = __es_insert_extent(inode, &newes);
	if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
					  128, EXT4_I(inode)))
		goto retry;
	if (err == -ENOMEM && !ext4_es_is_delayed(&newes))
		err = 0;

	if (sbi->s_cluster_ratio > 1 && test_opt(inode->i_sb, DELALLOC) &&
	    (status & EXTENT_STATUS_WRITTEN ||
	     status & EXTENT_STATUS_UNWRITTEN))
		__revise_pending(inode, lblk, len);

error:
	write_unlock(&EXT4_I(inode)->i_es_lock);

	ext4_es_print_tree(inode);

	return err;
}

/*
 * ext4_es_cache_extent() inserts information into the extent status
 * tree if and only if there isn't information about the range in
 * question already.
 */
void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk,
			  ext4_lblk_t len, ext4_fsblk_t pblk,
			  unsigned int status)
{
	struct extent_status *es;
	struct extent_status newes;
	ext4_lblk_t end = lblk + len - 1;

	newes.es_lblk = lblk;
	newes.es_len = len;
	ext4_es_store_pblock_status(&newes, pblk, status);
	trace_ext4_es_cache_extent(inode, &newes);

	if (!len)
		return;

	BUG_ON(end < lblk);

	write_lock(&EXT4_I(inode)->i_es_lock);

	es = __es_tree_search(&EXT4_I(inode)->i_es_tree.root, lblk);
	if (!es || es->es_lblk > end)
		__es_insert_extent(inode, &newes);
	write_unlock(&EXT4_I(inode)->i_es_lock);
}

/*
 * ext4_es_lookup_extent() looks up an extent in extent status tree.
 *
 * ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
 *
 * Return: 1 on found, 0 on not
 */
int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
			  struct extent_status *es)
{
	struct ext4_es_tree *tree;
	struct ext4_es_stats *stats;
	struct extent_status *es1 = NULL;
	struct rb_node *node;
	int found = 0;

	trace_ext4_es_lookup_extent_enter(inode, lblk);
	es_debug("lookup extent in block %u\n", lblk);

	tree = &EXT4_I(inode)->i_es_tree;
	read_lock(&EXT4_I(inode)->i_es_lock);

	/* find extent in cache firstly */
	es->es_lblk = es->es_len = es->es_pblk = 0;
	if (tree->cache_es) {
		es1 = tree->cache_es;
		if (in_range(lblk, es1->es_lblk, es1->es_len)) {
			es_debug("%u cached by [%u/%u)\n",
				 lblk, es1->es_lblk, es1->es_len);
			found = 1;
			goto out;
		}
	}

	node = tree->root.rb_node;
	while (node) {
		es1 = rb_entry(node, struct extent_status, rb_node);
		if (lblk < es1->es_lblk)
			node = node->rb_left;
		else if (lblk > ext4_es_end(es1))
			node = node->rb_right;
		else {
			found = 1;
			break;
		}
	}

out:
	stats = &EXT4_SB(inode->i_sb)->s_es_stats;
	if (found) {
		BUG_ON(!es1);
		es->es_lblk = es1->es_lblk;
		es->es_len = es1->es_len;
		es->es_pblk = es1->es_pblk;
		if (!ext4_es_is_referenced(es1))
			ext4_es_set_referenced(es1);
		stats->es_stats_cache_hits++;
	} else {
		stats->es_stats_cache_misses++;
	}

	read_unlock(&EXT4_I(inode)->i_es_lock);

	trace_ext4_es_lookup_extent_exit(inode, es, found);
	return found;
}

static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
			      ext4_lblk_t end)
{
	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
	struct rb_node *node;
	struct extent_status *es;
	struct extent_status orig_es;
	ext4_lblk_t len1, len2;
	ext4_fsblk_t block;
	int err;

retry:
	err = 0;
	es = __es_tree_search(&tree->root, lblk);
	if (!es)
		goto out;
	if (es->es_lblk > end)
		goto out;

	/* Simply invalidate cache_es. */
	tree->cache_es = NULL;

	orig_es.es_lblk = es->es_lblk;
	orig_es.es_len = es->es_len;
	orig_es.es_pblk = es->es_pblk;

	len1 = lblk > es->es_lblk ? lblk - es->es_lblk : 0;
	len2 = ext4_es_end(es) > end ? ext4_es_end(es) - end : 0;
	if (len1 > 0)
		es->es_len = len1;
	if (len2 > 0) {
		if (len1 > 0) {
			struct extent_status newes;

			newes.es_lblk = end + 1;
			newes.es_len = len2;
			block = 0x7FDEADBEEFULL;
			if (ext4_es_is_written(&orig_es) ||
			    ext4_es_is_unwritten(&orig_es))
				block = ext4_es_pblock(&orig_es) +
					orig_es.es_len - len2;
			ext4_es_store_pblock_status(&newes, block,
						    ext4_es_status(&orig_es));
			err = __es_insert_extent(inode, &newes);
			if (err) {
				es->es_lblk = orig_es.es_lblk;
				es->es_len = orig_es.es_len;
				if ((err == -ENOMEM) &&
				    __es_shrink(EXT4_SB(inode->i_sb),
							128, EXT4_I(inode)))
					goto retry;
				goto out;
			}
		} else {
			es->es_lblk = end + 1;
			es->es_len = len2;
			if (ext4_es_is_written(es) ||
			    ext4_es_is_unwritten(es)) {
				block = orig_es.es_pblk + orig_es.es_len - len2;
				ext4_es_store_pblock(es, block);
			}
		}
		goto out;
	}

	if (len1 > 0) {
		node = rb_next(&es->rb_node);
		if (node)
			es = rb_entry(node, struct extent_status, rb_node);
		else
			es = NULL;
	}

	while (es && ext4_es_end(es) <= end) {
		node = rb_next(&es->rb_node);
		rb_erase(&es->rb_node, &tree->root);
		ext4_es_free_extent(inode, es);
		if (!node) {
			es = NULL;
			break;
		}
		es = rb_entry(node, struct extent_status, rb_node);
	}

	if (es && es->es_lblk < end + 1) {
		ext4_lblk_t orig_len = es->es_len;

		len1 = ext4_es_end(es) - end;
		es->es_lblk = end + 1;
		es->es_len = len1;
		if (ext4_es_is_written(es) || ext4_es_is_unwritten(es)) {
			block = es->es_pblk + orig_len - len1;
			ext4_es_store_pblock(es, block);
		}
	}

out:
	return err;
}

/*
 * ext4_es_remove_extent() removes a space from a extent status tree.
 *
 * Return 0 on success, error code on failure.
 */
int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
			  ext4_lblk_t len)
{
	ext4_lblk_t end;
	int err = 0;

	trace_ext4_es_remove_extent(inode, lblk, len);
	es_debug("remove [%u/%u) from extent status tree of inode %lu\n",
		 lblk, len, inode->i_ino);

	if (!len)
		return err;

	end = lblk + len - 1;
	BUG_ON(end < lblk);

	/*
	 * ext4_clear_inode() depends on us taking i_es_lock unconditionally
	 * so that we are sure __es_shrink() is done with the inode before it
	 * is reclaimed.
	 */
	write_lock(&EXT4_I(inode)->i_es_lock);
	err = __es_remove_extent(inode, lblk, end);
	write_unlock(&EXT4_I(inode)->i_es_lock);
	ext4_es_print_tree(inode);
	return err;
}

static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
		       struct ext4_inode_info *locked_ei)
{
	struct ext4_inode_info *ei;
	struct ext4_es_stats *es_stats;
	ktime_t start_time;
	u64 scan_time;
	int nr_to_walk;
	int nr_shrunk = 0;
	int retried = 0, nr_skipped = 0;

	es_stats = &sbi->s_es_stats;
	start_time = ktime_get();

retry:
	spin_lock(&sbi->s_es_lock);
	nr_to_walk = sbi->s_es_nr_inode;
	while (nr_to_walk-- > 0) {
		if (list_empty(&sbi->s_es_list)) {
			spin_unlock(&sbi->s_es_lock);
			goto out;
		}
		ei = list_first_entry(&sbi->s_es_list, struct ext4_inode_info,
				      i_es_list);
		/* Move the inode to the tail */
		list_move_tail(&ei->i_es_list, &sbi->s_es_list);

		/*
		 * Normally we try hard to avoid shrinking precached inodes,
		 * but we will as a last resort.
		 */
		if (!retried && ext4_test_inode_state(&ei->vfs_inode,
						EXT4_STATE_EXT_PRECACHED)) {
			nr_skipped++;
			continue;
		}

		if (ei == locked_ei || !write_trylock(&ei->i_es_lock)) {
			nr_skipped++;
			continue;
		}
		/*
		 * Now we hold i_es_lock which protects us from inode reclaim
		 * freeing inode under us
		 */
		spin_unlock(&sbi->s_es_lock);

		nr_shrunk += es_reclaim_extents(ei, &nr_to_scan);
		write_unlock(&ei->i_es_lock);

		if (nr_to_scan <= 0)
			goto out;
		spin_lock(&sbi->s_es_lock);
	}
	spin_unlock(&sbi->s_es_lock);

	/*
	 * If we skipped any inodes, and we weren't able to make any
	 * forward progress, try again to scan precached inodes.
	 */
	if ((nr_shrunk == 0) && nr_skipped && !retried) {
		retried++;
		goto retry;
	}

	if (locked_ei && nr_shrunk == 0)
		nr_shrunk = es_reclaim_extents(locked_ei, &nr_to_scan);

out:
	scan_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
	if (likely(es_stats->es_stats_scan_time))
		es_stats->es_stats_scan_time = (scan_time +
				es_stats->es_stats_scan_time*3) / 4;
	else
		es_stats->es_stats_scan_time = scan_time;
	if (scan_time > es_stats->es_stats_max_scan_time)
		es_stats->es_stats_max_scan_time = scan_time;
	if (likely(es_stats->es_stats_shrunk))
		es_stats->es_stats_shrunk = (nr_shrunk +
				es_stats->es_stats_shrunk*3) / 4;
	else
		es_stats->es_stats_shrunk = nr_shrunk;

	trace_ext4_es_shrink(sbi->s_sb, nr_shrunk, scan_time,
			     nr_skipped, retried);
	return nr_shrunk;
}

static unsigned long ext4_es_count(struct shrinker *shrink,
				   struct shrink_control *sc)
{
	unsigned long nr;
	struct ext4_sb_info *sbi;

	sbi = container_of(shrink, struct ext4_sb_info, s_es_shrinker);
	nr = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
	trace_ext4_es_shrink_count(sbi->s_sb, sc->nr_to_scan, nr);
	return nr;
}

static unsigned long ext4_es_scan(struct shrinker *shrink,
				  struct shrink_control *sc)
{
	struct ext4_sb_info *sbi = container_of(shrink,
					struct ext4_sb_info, s_es_shrinker);
	int nr_to_scan = sc->nr_to_scan;
	int ret, nr_shrunk;

	ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
	trace_ext4_es_shrink_scan_enter(sbi->s_sb, nr_to_scan, ret);

	if (!nr_to_scan)
		return ret;

	nr_shrunk = __es_shrink(sbi, nr_to_scan, NULL);

	trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);
	return nr_shrunk;
}

int ext4_seq_es_shrinker_info_show(struct seq_file *seq, void *v)
{
	struct ext4_sb_info *sbi = EXT4_SB((struct super_block *) seq->private);
	struct ext4_es_stats *es_stats = &sbi->s_es_stats;
	struct ext4_inode_info *ei, *max = NULL;
	unsigned int inode_cnt = 0;

	if (v != SEQ_START_TOKEN)
		return 0;

	/* here we just find an inode that has the max nr. of objects */
	spin_lock(&sbi->s_es_lock);
	list_for_each_entry(ei, &sbi->s_es_list, i_es_list) {
		inode_cnt++;
		if (max && max->i_es_all_nr < ei->i_es_all_nr)
			max = ei;
		else if (!max)
			max = ei;
	}
	spin_unlock(&sbi->s_es_lock);

	seq_printf(seq, "stats:\n  %lld objects\n  %lld reclaimable objects\n",
		   percpu_counter_sum_positive(&es_stats->es_stats_all_cnt),
		   percpu_counter_sum_positive(&es_stats->es_stats_shk_cnt));
	seq_printf(seq, "  %lu/%lu cache hits/misses\n",
		   es_stats->es_stats_cache_hits,
		   es_stats->es_stats_cache_misses);
	if (inode_cnt)
		seq_printf(seq, "  %d inodes on list\n", inode_cnt);

	seq_printf(seq, "average:\n  %llu us scan time\n",
	    div_u64(es_stats->es_stats_scan_time, 1000));
	seq_printf(seq, "  %lu shrunk objects\n", es_stats->es_stats_shrunk);
	if (inode_cnt)
		seq_printf(seq,
		    "maximum:\n  %lu inode (%u objects, %u reclaimable)\n"
		    "  %llu us max scan time\n",
		    max->vfs_inode.i_ino, max->i_es_all_nr, max->i_es_shk_nr,
		    div_u64(es_stats->es_stats_max_scan_time, 1000));

	return 0;
}

int ext4_es_register_shrinker(struct ext4_sb_info *sbi)
{
	int err;

	/* Make sure we have enough bits for physical block number */
	BUILD_BUG_ON(ES_SHIFT < 48);
	INIT_LIST_HEAD(&sbi->s_es_list);
	sbi->s_es_nr_inode = 0;
	spin_lock_init(&sbi->s_es_lock);
	sbi->s_es_stats.es_stats_shrunk = 0;
	sbi->s_es_stats.es_stats_cache_hits = 0;
	sbi->s_es_stats.es_stats_cache_misses = 0;
	sbi->s_es_stats.es_stats_scan_time = 0;
	sbi->s_es_stats.es_stats_max_scan_time = 0;
	err = percpu_counter_init(&sbi->s_es_stats.es_stats_all_cnt, 0, GFP_KERNEL);
	if (err)
		return err;
	err = percpu_counter_init(&sbi->s_es_stats.es_stats_shk_cnt, 0, GFP_KERNEL);
	if (err)
		goto err1;

	sbi->s_es_shrinker.scan_objects = ext4_es_scan;
	sbi->s_es_shrinker.count_objects = ext4_es_count;
	sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
	err = register_shrinker(&sbi->s_es_shrinker);
	if (err)
		goto err2;

	return 0;

err2:
	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
err1:
	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
	return err;
}

void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
{
	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
	unregister_shrinker(&sbi->s_es_shrinker);
}

/*
 * Shrink extents in given inode from ei->i_es_shrink_lblk till end. Scan at
 * most *nr_to_scan extents, update *nr_to_scan accordingly.
 *
 * Return 0 if we hit end of tree / interval, 1 if we exhausted nr_to_scan.
 * Increment *nr_shrunk by the number of reclaimed extents. Also update
 * ei->i_es_shrink_lblk to where we should continue scanning.
 */
static int es_do_reclaim_extents(struct ext4_inode_info *ei, ext4_lblk_t end,
				 int *nr_to_scan, int *nr_shrunk)
{
	struct inode *inode = &ei->vfs_inode;
	struct ext4_es_tree *tree = &ei->i_es_tree;
	struct extent_status *es;
	struct rb_node *node;

	es = __es_tree_search(&tree->root, ei->i_es_shrink_lblk);
	if (!es)
		goto out_wrap;
	while (*nr_to_scan > 0) {
		if (es->es_lblk > end) {
			ei->i_es_shrink_lblk = end + 1;
			return 0;
		}

		(*nr_to_scan)--;
		node = rb_next(&es->rb_node);
		/*
		 * We can't reclaim delayed extent from status tree because
		 * fiemap, bigallic, and seek_data/hole need to use it.
		 */
		if (ext4_es_is_delayed(es))
			goto next;
		if (ext4_es_is_referenced(es)) {
			ext4_es_clear_referenced(es);
			goto next;
		}

		rb_erase(&es->rb_node, &tree->root);
		ext4_es_free_extent(inode, es);
		(*nr_shrunk)++;
next:
		if (!node)
			goto out_wrap;
		es = rb_entry(node, struct extent_status, rb_node);
	}
	ei->i_es_shrink_lblk = es->es_lblk;
	return 1;
out_wrap:
	ei->i_es_shrink_lblk = 0;
	return 0;
}

static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan)
{
	struct inode *inode = &ei->vfs_inode;
	int nr_shrunk = 0;
	ext4_lblk_t start = ei->i_es_shrink_lblk;
	static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
				      DEFAULT_RATELIMIT_BURST);

	if (ei->i_es_shk_nr == 0)
		return 0;

	if (ext4_test_inode_state(inode, EXT4_STATE_EXT_PRECACHED) &&
	    __ratelimit(&_rs))
		ext4_warning(inode->i_sb, "forced shrink of precached extents");

	if (!es_do_reclaim_extents(ei, EXT_MAX_BLOCKS, nr_to_scan, &nr_shrunk) &&
	    start != 0)
		es_do_reclaim_extents(ei, start - 1, nr_to_scan, &nr_shrunk);

	ei->i_es_tree.cache_es = NULL;
	return nr_shrunk;
}

#ifdef ES_DEBUG__
static void ext4_print_pending_tree(struct inode *inode)
{
	struct ext4_pending_tree *tree;
	struct rb_node *node;
	struct pending_reservation *pr;

	printk(KERN_DEBUG "pending reservations for inode %lu:", inode->i_ino);
	tree = &EXT4_I(inode)->i_pending_tree;
	node = rb_first(&tree->root);
	while (node) {
		pr = rb_entry(node, struct pending_reservation, rb_node);
		printk(KERN_DEBUG " %u", pr->lclu);
		node = rb_next(node);
	}
	printk(KERN_DEBUG "\n");
}
#else
#define ext4_print_pending_tree(inode)
#endif

int __init ext4_init_pending(void)
{
	ext4_pending_cachep = kmem_cache_create("ext4_pending_reservation",
					   sizeof(struct pending_reservation),
					   0, (SLAB_RECLAIM_ACCOUNT), NULL);
	if (ext4_pending_cachep == NULL)
		return -ENOMEM;
	return 0;
}

void ext4_exit_pending(void)
{
	kmem_cache_destroy(ext4_pending_cachep);
}

void ext4_init_pending_tree(struct ext4_pending_tree *tree)
{
	tree->root = RB_ROOT;
}

/*
 * __get_pending - retrieve a pointer to a pending reservation
 *
 * @inode - file containing the pending cluster reservation
 * @lclu - logical cluster of interest
 *
 * Returns a pointer to a pending reservation if it's a member of
 * the set, and NULL if not.  Must be called holding i_es_lock.
 */
static struct pending_reservation *__get_pending(struct inode *inode,
						 ext4_lblk_t lclu)
{
	struct ext4_pending_tree *tree;
	struct rb_node *node;
	struct pending_reservation *pr = NULL;

	tree = &EXT4_I(inode)->i_pending_tree;
	node = (&tree->root)->rb_node;

	while (node) {
		pr = rb_entry(node, struct pending_reservation, rb_node);
		if (lclu < pr->lclu)
			node = node->rb_left;
		else if (lclu > pr->lclu)
			node = node->rb_right;
		else if (lclu == pr->lclu)
			return pr;
	}
	return NULL;
}

/*
 * __insert_pending - adds a pending cluster reservation to the set of
 *                    pending reservations
 *
 * @inode - file containing the cluster
 * @lblk - logical block in the cluster to be added
 *
 * Returns 0 on successful insertion and -ENOMEM on failure.  If the
 * pending reservation is already in the set, returns successfully.
 */
static int __insert_pending(struct inode *inode, ext4_lblk_t lblk)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	struct ext4_pending_tree *tree = &EXT4_I(inode)->i_pending_tree;
	struct rb_node **p = &tree->root.rb_node;
	struct rb_node *parent = NULL;
	struct pending_reservation *pr;
	ext4_lblk_t lclu;
	int ret = 0;

	lclu = EXT4_B2C(sbi, lblk);
	/* search to find parent for insertion */
	while (*p) {
		parent = *p;
		pr = rb_entry(parent, struct pending_reservation, rb_node);

		if (lclu < pr->lclu) {
			p = &(*p)->rb_left;
		} else if (lclu > pr->lclu) {
			p = &(*p)->rb_right;
		} else {
			/* pending reservation already inserted */
			goto out;
		}
	}

	pr = kmem_cache_alloc(ext4_pending_cachep, GFP_ATOMIC);
	if (pr == NULL) {
		ret = -ENOMEM;
		goto out;
	}
	pr->lclu = lclu;

	rb_link_node(&pr->rb_node, parent, p);
	rb_insert_color(&pr->rb_node, &tree->root);

out:
	return ret;
}

/*
 * __remove_pending - removes a pending cluster reservation from the set
 *                    of pending reservations
 *
 * @inode - file containing the cluster
 * @lblk - logical block in the pending cluster reservation to be removed
 *
 * Returns successfully if pending reservation is not a member of the set.
 */
static void __remove_pending(struct inode *inode, ext4_lblk_t lblk)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	struct pending_reservation *pr;
	struct ext4_pending_tree *tree;

	pr = __get_pending(inode, EXT4_B2C(sbi, lblk));
	if (pr != NULL) {
		tree = &EXT4_I(inode)->i_pending_tree;
		rb_erase(&pr->rb_node, &tree->root);
		kmem_cache_free(ext4_pending_cachep, pr);
	}
}

/*
 * ext4_remove_pending - removes a pending cluster reservation from the set
 *                       of pending reservations
 *
 * @inode - file containing the cluster
 * @lblk - logical block in the pending cluster reservation to be removed
 *
 * Locking for external use of __remove_pending.
 */
void ext4_remove_pending(struct inode *inode, ext4_lblk_t lblk)
{
	struct ext4_inode_info *ei = EXT4_I(inode);

	write_lock(&ei->i_es_lock);
	__remove_pending(inode, lblk);
	write_unlock(&ei->i_es_lock);
}

/*
 * ext4_is_pending - determine whether a cluster has a pending reservation
 *                   on it
 *
 * @inode - file containing the cluster
 * @lblk - logical block in the cluster
 *
 * Returns true if there's a pending reservation for the cluster in the
 * set of pending reservations, and false if not.
 */
bool ext4_is_pending(struct inode *inode, ext4_lblk_t lblk)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	struct ext4_inode_info *ei = EXT4_I(inode);
	bool ret;

	read_lock(&ei->i_es_lock);
	ret = (bool)(__get_pending(inode, EXT4_B2C(sbi, lblk)) != NULL);
	read_unlock(&ei->i_es_lock);

	return ret;
}

/*
 * ext4_es_insert_delayed_block - adds a delayed block to the extents status
 *                                tree, adding a pending reservation where
 *                                needed
 *
 * @inode - file containing the newly added block
 * @lblk - logical block to be added
 * @allocated - indicates whether a physical cluster has been allocated for
 *              the logical cluster that contains the block
 *
 * Returns 0 on success, negative error code on failure.
 */
int ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
				 bool allocated)
{
	struct extent_status newes;
	int err = 0;

	es_debug("add [%u/1) delayed to extent status tree of inode %lu\n",
		 lblk, inode->i_ino);

	newes.es_lblk = lblk;
	newes.es_len = 1;
	ext4_es_store_pblock_status(&newes, ~0, EXTENT_STATUS_DELAYED);
	trace_ext4_es_insert_delayed_block(inode, &newes, allocated);

	ext4_es_insert_extent_check(inode, &newes);

	write_lock(&EXT4_I(inode)->i_es_lock);

	err = __es_remove_extent(inode, lblk, lblk);
	if (err != 0)
		goto error;
retry:
	err = __es_insert_extent(inode, &newes);
	if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
					  128, EXT4_I(inode)))
		goto retry;
	if (err != 0)
		goto error;

	if (allocated)
		__insert_pending(inode, lblk);

error:
	write_unlock(&EXT4_I(inode)->i_es_lock);

	ext4_es_print_tree(inode);
	ext4_print_pending_tree(inode);

	return err;
}

/*
 * __es_delayed_clu - count number of clusters containing blocks that
 *                    are delayed only
 *
 * @inode - file containing block range
 * @start - logical block defining start of range
 * @end - logical block defining end of range
 *
 * Returns the number of clusters containing only delayed (not delayed
 * and unwritten) blocks in the range specified by @start and @end.  Any
 * cluster or part of a cluster within the range and containing a delayed
 * and not unwritten block within the range is counted as a whole cluster.
 */
static unsigned int __es_delayed_clu(struct inode *inode, ext4_lblk_t start,
				     ext4_lblk_t end)
{
	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
	struct extent_status *es;
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	struct rb_node *node;
	ext4_lblk_t first_lclu, last_lclu;
	unsigned long long last_counted_lclu;
	unsigned int n = 0;

	/* guaranteed to be unequal to any ext4_lblk_t value */
	last_counted_lclu = ~0ULL;

	es = __es_tree_search(&tree->root, start);

	while (es && (es->es_lblk <= end)) {
		if (ext4_es_is_delonly(es)) {
			if (es->es_lblk <= start)
				first_lclu = EXT4_B2C(sbi, start);
			else
				first_lclu = EXT4_B2C(sbi, es->es_lblk);

			if (ext4_es_end(es) >= end)
				last_lclu = EXT4_B2C(sbi, end);
			else
				last_lclu = EXT4_B2C(sbi, ext4_es_end(es));

			if (first_lclu == last_counted_lclu)
				n += last_lclu - first_lclu;
			else
				n += last_lclu - first_lclu + 1;
			last_counted_lclu = last_lclu;
		}
		node = rb_next(&es->rb_node);
		if (!node)
			break;
		es = rb_entry(node, struct extent_status, rb_node);
	}

	return n;
}

/*
 * ext4_es_delayed_clu - count number of clusters containing blocks that
 *                       are both delayed and unwritten
 *
 * @inode - file containing block range
 * @lblk - logical block defining start of range
 * @len - number of blocks in range
 *
 * Locking for external use of __es_delayed_clu().
 */
unsigned int ext4_es_delayed_clu(struct inode *inode, ext4_lblk_t lblk,
				 ext4_lblk_t len)
{
	struct ext4_inode_info *ei = EXT4_I(inode);
	ext4_lblk_t end;
	unsigned int n;

	if (len == 0)
		return 0;

	end = lblk + len - 1;
	WARN_ON(end < lblk);

	read_lock(&ei->i_es_lock);

	n = __es_delayed_clu(inode, lblk, end);

	read_unlock(&ei->i_es_lock);

	return n;
}

/*
 * __revise_pending - makes, cancels, or leaves unchanged pending cluster
 *                    reservations for a specified block range depending
 *                    upon the presence or absence of delayed blocks
 *                    outside the range within clusters at the ends of the
 *                    range
 *
 * @inode - file containing the range
 * @lblk - logical block defining the start of range
 * @len  - length of range in blocks
 *
 * Used after a newly allocated extent is added to the extents status tree.
 * Requires that the extents in the range have either written or unwritten
 * status.  Must be called while holding i_es_lock.
 */
static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
			     ext4_lblk_t len)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	ext4_lblk_t end = lblk + len - 1;
	ext4_lblk_t first, last;
	bool f_del = false, l_del = false;

	if (len == 0)
		return;

	/*
	 * Two cases - block range within single cluster and block range
	 * spanning two or more clusters.  Note that a cluster belonging
	 * to a range starting and/or ending on a cluster boundary is treated
	 * as if it does not contain a delayed extent.  The new range may
	 * have allocated space for previously delayed blocks out to the
	 * cluster boundary, requiring that any pre-existing pending
	 * reservation be canceled.  Because this code only looks at blocks
	 * outside the range, it should revise pending reservations
	 * correctly even if the extent represented by the range can't be
	 * inserted in the extents status tree due to ENOSPC.
	 */

	if (EXT4_B2C(sbi, lblk) == EXT4_B2C(sbi, end)) {
		first = EXT4_LBLK_CMASK(sbi, lblk);
		if (first != lblk)
			f_del = __es_scan_range(inode, &ext4_es_is_delonly,
						first, lblk - 1);
		if (f_del) {
			__insert_pending(inode, first);
		} else {
			last = EXT4_LBLK_CMASK(sbi, end) +
			       sbi->s_cluster_ratio - 1;
			if (last != end)
				l_del = __es_scan_range(inode,
							&ext4_es_is_delonly,
							end + 1, last);
			if (l_del)
				__insert_pending(inode, last);
			else
				__remove_pending(inode, last);
		}
	} else {
		first = EXT4_LBLK_CMASK(sbi, lblk);
		if (first != lblk)
			f_del = __es_scan_range(inode, &ext4_es_is_delonly,
						first, lblk - 1);
		if (f_del)
			__insert_pending(inode, first);
		else
			__remove_pending(inode, first);

		last = EXT4_LBLK_CMASK(sbi, end) + sbi->s_cluster_ratio - 1;
		if (last != end)
			l_del = __es_scan_range(inode, &ext4_es_is_delonly,
						end + 1, last);
		if (l_del)
			__insert_pending(inode, last);
		else
			__remove_pending(inode, last);
	}
}

/*
 * ext4_es_remove_blks - remove block range from extents status tree and
 *                       reduce reservation count or cancel pending
 *                       reservation as needed
 *
 * @inode - file containing range
 * @lblk - first block in range
 * @len - number of blocks to remove
 *
 */
void ext4_es_remove_blks(struct inode *inode, ext4_lblk_t lblk,
			 ext4_lblk_t len)
{
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	unsigned int clu_size, reserved = 0;
	ext4_lblk_t last_lclu, first, length, remainder, last;
	bool delonly;
	int err = 0;
	struct pending_reservation *pr;
	struct ext4_pending_tree *tree;

	/*
	 * Process cluster by cluster for bigalloc - there may be up to
	 * two clusters in a 4k page with a 1k block size and two blocks
	 * per cluster.  Also necessary for systems with larger page sizes
	 * and potentially larger block sizes.
	 */
	clu_size = sbi->s_cluster_ratio;
	last_lclu = EXT4_B2C(sbi, lblk + len - 1);

	write_lock(&EXT4_I(inode)->i_es_lock);

	for (first = lblk, remainder = len;
	     remainder > 0;
	     first += length, remainder -= length) {

		if (EXT4_B2C(sbi, first) == last_lclu)
			length = remainder;
		else
			length = clu_size - EXT4_LBLK_COFF(sbi, first);

		/*
		 * The BH_Delay flag, which triggers calls to this function,
		 * and the contents of the extents status tree can be
		 * inconsistent due to writepages activity. So, note whether
		 * the blocks to be removed actually belong to an extent with
		 * delayed only status.
		 */
		delonly = __es_scan_clu(inode, &ext4_es_is_delonly, first);

		/*
		 * because of the writepages effect, written and unwritten
		 * blocks could be removed here
		 */
		last = first + length - 1;
		err = __es_remove_extent(inode, first, last);
		if (err)
			ext4_warning(inode->i_sb,
				     "%s: couldn't remove page (err = %d)",
				     __func__, err);

		/* non-bigalloc case: simply count the cluster for release */
		if (sbi->s_cluster_ratio == 1 && delonly) {
			reserved++;
			continue;
		}

		/*
		 * bigalloc case: if all delayed allocated only blocks have
		 * just been removed from a cluster, either cancel a pending
		 * reservation if it exists or count a cluster for release
		 */
		if (delonly &&
		    !__es_scan_clu(inode, &ext4_es_is_delonly, first)) {
			pr = __get_pending(inode, EXT4_B2C(sbi, first));
			if (pr != NULL) {
				tree = &EXT4_I(inode)->i_pending_tree;
				rb_erase(&pr->rb_node, &tree->root);
				kmem_cache_free(ext4_pending_cachep, pr);
			} else {
				reserved++;
			}
		}
	}

	write_unlock(&EXT4_I(inode)->i_es_lock);

	ext4_da_release_space(inode, reserved);
}