summaryrefslogtreecommitdiff
path: root/include/linux/pagemap.h
blob: 58f395f3febe5b4c68b62feb180dc295819ddaad (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
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PAGEMAP_H
#define _LINUX_PAGEMAP_H

/*
 * Copyright 1995 Linus Torvalds
 */
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/compiler.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
#include <linux/bitops.h>
#include <linux/hardirq.h> /* for in_interrupt() */
#include <linux/hugetlb_inline.h>

struct folio_batch;

unsigned long invalidate_mapping_pages(struct address_space *mapping,
					pgoff_t start, pgoff_t end);

static inline void invalidate_remote_inode(struct inode *inode)
{
	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
	    S_ISLNK(inode->i_mode))
		invalidate_mapping_pages(inode->i_mapping, 0, -1);
}
int invalidate_inode_pages2(struct address_space *mapping);
int invalidate_inode_pages2_range(struct address_space *mapping,
		pgoff_t start, pgoff_t end);
int write_inode_now(struct inode *, int sync);
int filemap_fdatawrite(struct address_space *);
int filemap_flush(struct address_space *);
int filemap_fdatawait_keep_errors(struct address_space *mapping);
int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend);
int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
		loff_t start_byte, loff_t end_byte);

static inline int filemap_fdatawait(struct address_space *mapping)
{
	return filemap_fdatawait_range(mapping, 0, LLONG_MAX);
}

bool filemap_range_has_page(struct address_space *, loff_t lstart, loff_t lend);
int filemap_write_and_wait_range(struct address_space *mapping,
		loff_t lstart, loff_t lend);
int __filemap_fdatawrite_range(struct address_space *mapping,
		loff_t start, loff_t end, int sync_mode);
int filemap_fdatawrite_range(struct address_space *mapping,
		loff_t start, loff_t end);
int filemap_check_errors(struct address_space *mapping);
void __filemap_set_wb_err(struct address_space *mapping, int err);
int filemap_fdatawrite_wbc(struct address_space *mapping,
			   struct writeback_control *wbc);

static inline int filemap_write_and_wait(struct address_space *mapping)
{
	return filemap_write_and_wait_range(mapping, 0, LLONG_MAX);
}

/**
 * filemap_set_wb_err - set a writeback error on an address_space
 * @mapping: mapping in which to set writeback error
 * @err: error to be set in mapping
 *
 * When writeback fails in some way, we must record that error so that
 * userspace can be informed when fsync and the like are called.  We endeavor
 * to report errors on any file that was open at the time of the error.  Some
 * internal callers also need to know when writeback errors have occurred.
 *
 * When a writeback error occurs, most filesystems will want to call
 * filemap_set_wb_err to record the error in the mapping so that it will be
 * automatically reported whenever fsync is called on the file.
 */
static inline void filemap_set_wb_err(struct address_space *mapping, int err)
{
	/* Fastpath for common case of no error */
	if (unlikely(err))
		__filemap_set_wb_err(mapping, err);
}

/**
 * filemap_check_wb_err - has an error occurred since the mark was sampled?
 * @mapping: mapping to check for writeback errors
 * @since: previously-sampled errseq_t
 *
 * Grab the errseq_t value from the mapping, and see if it has changed "since"
 * the given value was sampled.
 *
 * If it has then report the latest error set, otherwise return 0.
 */
static inline int filemap_check_wb_err(struct address_space *mapping,
					errseq_t since)
{
	return errseq_check(&mapping->wb_err, since);
}

/**
 * filemap_sample_wb_err - sample the current errseq_t to test for later errors
 * @mapping: mapping to be sampled
 *
 * Writeback errors are always reported relative to a particular sample point
 * in the past. This function provides those sample points.
 */
static inline errseq_t filemap_sample_wb_err(struct address_space *mapping)
{
	return errseq_sample(&mapping->wb_err);
}

/**
 * file_sample_sb_err - sample the current errseq_t to test for later errors
 * @file: file pointer to be sampled
 *
 * Grab the most current superblock-level errseq_t value for the given
 * struct file.
 */
static inline errseq_t file_sample_sb_err(struct file *file)
{
	return errseq_sample(&file->f_path.dentry->d_sb->s_wb_err);
}

/*
 * Flush file data before changing attributes.  Caller must hold any locks
 * required to prevent further writes to this file until we're done setting
 * flags.
 */
static inline int inode_drain_writes(struct inode *inode)
{
	inode_dio_wait(inode);
	return filemap_write_and_wait(inode->i_mapping);
}

static inline bool mapping_empty(struct address_space *mapping)
{
	return xa_empty(&mapping->i_pages);
}

/*
 * mapping_shrinkable - test if page cache state allows inode reclaim
 * @mapping: the page cache mapping
 *
 * This checks the mapping's cache state for the pupose of inode
 * reclaim and LRU management.
 *
 * The caller is expected to hold the i_lock, but is not required to
 * hold the i_pages lock, which usually protects cache state. That's
 * because the i_lock and the list_lru lock that protect the inode and
 * its LRU state don't nest inside the irq-safe i_pages lock.
 *
 * Cache deletions are performed under the i_lock, which ensures that
 * when an inode goes empty, it will reliably get queued on the LRU.
 *
 * Cache additions do not acquire the i_lock and may race with this
 * check, in which case we'll report the inode as shrinkable when it
 * has cache pages. This is okay: the shrinker also checks the
 * refcount and the referenced bit, which will be elevated or set in
 * the process of adding new cache pages to an inode.
 */
static inline bool mapping_shrinkable(struct address_space *mapping)
{
	void *head;

	/*
	 * On highmem systems, there could be lowmem pressure from the
	 * inodes before there is highmem pressure from the page
	 * cache. Make inodes shrinkable regardless of cache state.
	 */
	if (IS_ENABLED(CONFIG_HIGHMEM))
		return true;

	/* Cache completely empty? Shrink away. */
	head = rcu_access_pointer(mapping->i_pages.xa_head);
	if (!head)
		return true;

	/*
	 * The xarray stores single offset-0 entries directly in the
	 * head pointer, which allows non-resident page cache entries
	 * to escape the shadow shrinker's list of xarray nodes. The
	 * inode shrinker needs to pick them up under memory pressure.
	 */
	if (!xa_is_node(head) && xa_is_value(head))
		return true;

	return false;
}

/*
 * Bits in mapping->flags.
 */
enum mapping_flags {
	AS_EIO		= 0,	/* IO error on async write */
	AS_ENOSPC	= 1,	/* ENOSPC on async write */
	AS_MM_ALL_LOCKS	= 2,	/* under mm_take_all_locks() */
	AS_UNEVICTABLE	= 3,	/* e.g., ramdisk, SHM_LOCK */
	AS_EXITING	= 4, 	/* final truncate in progress */
	/* writeback related tags are not used */
	AS_NO_WRITEBACK_TAGS = 5,
	AS_LARGE_FOLIO_SUPPORT = 6,
};

/**
 * mapping_set_error - record a writeback error in the address_space
 * @mapping: the mapping in which an error should be set
 * @error: the error to set in the mapping
 *
 * When writeback fails in some way, we must record that error so that
 * userspace can be informed when fsync and the like are called.  We endeavor
 * to report errors on any file that was open at the time of the error.  Some
 * internal callers also need to know when writeback errors have occurred.
 *
 * When a writeback error occurs, most filesystems will want to call
 * mapping_set_error to record the error in the mapping so that it can be
 * reported when the application calls fsync(2).
 */
static inline void mapping_set_error(struct address_space *mapping, int error)
{
	if (likely(!error))
		return;

	/* Record in wb_err for checkers using errseq_t based tracking */
	__filemap_set_wb_err(mapping, error);

	/* Record it in superblock */
	if (mapping->host)
		errseq_set(&mapping->host->i_sb->s_wb_err, error);

	/* Record it in flags for now, for legacy callers */
	if (error == -ENOSPC)
		set_bit(AS_ENOSPC, &mapping->flags);
	else
		set_bit(AS_EIO, &mapping->flags);
}

static inline void mapping_set_unevictable(struct address_space *mapping)
{
	set_bit(AS_UNEVICTABLE, &mapping->flags);
}

static inline void mapping_clear_unevictable(struct address_space *mapping)
{
	clear_bit(AS_UNEVICTABLE, &mapping->flags);
}

static inline bool mapping_unevictable(struct address_space *mapping)
{
	return mapping && test_bit(AS_UNEVICTABLE, &mapping->flags);
}

static inline void mapping_set_exiting(struct address_space *mapping)
{
	set_bit(AS_EXITING, &mapping->flags);
}

static inline int mapping_exiting(struct address_space *mapping)
{
	return test_bit(AS_EXITING, &mapping->flags);
}

static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
{
	set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
}

static inline int mapping_use_writeback_tags(struct address_space *mapping)
{
	return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
}

static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
{
	return mapping->gfp_mask;
}

/* Restricts the given gfp_mask to what the mapping allows. */
static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
		gfp_t gfp_mask)
{
	return mapping_gfp_mask(mapping) & gfp_mask;
}

/*
 * This is non-atomic.  Only to be used before the mapping is activated.
 * Probably needs a barrier...
 */
static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
{
	m->gfp_mask = mask;
}

/**
 * mapping_set_large_folios() - Indicate the file supports large folios.
 * @mapping: The file.
 *
 * The filesystem should call this function in its inode constructor to
 * indicate that the VFS can use large folios to cache the contents of
 * the file.
 *
 * Context: This should not be called while the inode is active as it
 * is non-atomic.
 */
static inline void mapping_set_large_folios(struct address_space *mapping)
{
	__set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
}

/*
 * Large folio support currently depends on THP.  These dependencies are
 * being worked on but are not yet fixed.
 */
static inline bool mapping_large_folio_support(struct address_space *mapping)
{
	return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
		test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
}

static inline int filemap_nr_thps(struct address_space *mapping)
{
#ifdef CONFIG_READ_ONLY_THP_FOR_FS
	return atomic_read(&mapping->nr_thps);
#else
	return 0;
#endif
}

static inline void filemap_nr_thps_inc(struct address_space *mapping)
{
#ifdef CONFIG_READ_ONLY_THP_FOR_FS
	if (!mapping_large_folio_support(mapping))
		atomic_inc(&mapping->nr_thps);
#else
	WARN_ON_ONCE(mapping_large_folio_support(mapping) == 0);
#endif
}

static inline void filemap_nr_thps_dec(struct address_space *mapping)
{
#ifdef CONFIG_READ_ONLY_THP_FOR_FS
	if (!mapping_large_folio_support(mapping))
		atomic_dec(&mapping->nr_thps);
#else
	WARN_ON_ONCE(mapping_large_folio_support(mapping) == 0);
#endif
}

void release_pages(struct page **pages, int nr);

struct address_space *page_mapping(struct page *);
struct address_space *folio_mapping(struct folio *);
struct address_space *swapcache_mapping(struct folio *);

/**
 * folio_file_mapping - Find the mapping this folio belongs to.
 * @folio: The folio.
 *
 * For folios which are in the page cache, return the mapping that this
 * page belongs to.  Folios in the swap cache return the mapping of the
 * swap file or swap device where the data is stored.  This is different
 * from the mapping returned by folio_mapping().  The only reason to
 * use it is if, like NFS, you return 0 from ->activate_swapfile.
 *
 * Do not call this for folios which aren't in the page cache or swap cache.
 */
static inline struct address_space *folio_file_mapping(struct folio *folio)
{
	if (unlikely(folio_test_swapcache(folio)))
		return swapcache_mapping(folio);

	return folio->mapping;
}

static inline struct address_space *page_file_mapping(struct page *page)
{
	return folio_file_mapping(page_folio(page));
}

/*
 * For file cache pages, return the address_space, otherwise return NULL
 */
static inline struct address_space *page_mapping_file(struct page *page)
{
	struct folio *folio = page_folio(page);

	if (unlikely(folio_test_swapcache(folio)))
		return NULL;
	return folio_mapping(folio);
}

/**
 * folio_inode - Get the host inode for this folio.
 * @folio: The folio.
 *
 * For folios which are in the page cache, return the inode that this folio
 * belongs to.
 *
 * Do not call this for folios which aren't in the page cache.
 */
static inline struct inode *folio_inode(struct folio *folio)
{
	return folio->mapping->host;
}

/**
 * folio_attach_private - Attach private data to a folio.
 * @folio: Folio to attach data to.
 * @data: Data to attach to folio.
 *
 * Attaching private data to a folio increments the page's reference count.
 * The data must be detached before the folio will be freed.
 */
static inline void folio_attach_private(struct folio *folio, void *data)
{
	folio_get(folio);
	folio->private = data;
	folio_set_private(folio);
}

/**
 * folio_change_private - Change private data on a folio.
 * @folio: Folio to change the data on.
 * @data: Data to set on the folio.
 *
 * Change the private data attached to a folio and return the old
 * data.  The page must previously have had data attached and the data
 * must be detached before the folio will be freed.
 *
 * Return: Data that was previously attached to the folio.
 */
static inline void *folio_change_private(struct folio *folio, void *data)
{
	void *old = folio_get_private(folio);

	folio->private = data;
	return old;
}

/**
 * folio_detach_private - Detach private data from a folio.
 * @folio: Folio to detach data from.
 *
 * Removes the data that was previously attached to the folio and decrements
 * the refcount on the page.
 *
 * Return: Data that was attached to the folio.
 */
static inline void *folio_detach_private(struct folio *folio)
{
	void *data = folio_get_private(folio);

	if (!folio_test_private(folio))
		return NULL;
	folio_clear_private(folio);
	folio->private = NULL;
	folio_put(folio);

	return data;
}

static inline void attach_page_private(struct page *page, void *data)
{
	folio_attach_private(page_folio(page), data);
}

static inline void *detach_page_private(struct page *page)
{
	return folio_detach_private(page_folio(page));
}

#ifdef CONFIG_NUMA
struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order);
#else
static inline struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order)
{
	return folio_alloc(gfp, order);
}
#endif

static inline struct page *__page_cache_alloc(gfp_t gfp)
{
	return &filemap_alloc_folio(gfp, 0)->page;
}

static inline struct page *page_cache_alloc(struct address_space *x)
{
	return __page_cache_alloc(mapping_gfp_mask(x));
}

static inline gfp_t readahead_gfp_mask(struct address_space *x)
{
	return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
}

typedef int filler_t(void *, struct page *);

pgoff_t page_cache_next_miss(struct address_space *mapping,
			     pgoff_t index, unsigned long max_scan);
pgoff_t page_cache_prev_miss(struct address_space *mapping,
			     pgoff_t index, unsigned long max_scan);

#define FGP_ACCESSED		0x00000001
#define FGP_LOCK		0x00000002
#define FGP_CREAT		0x00000004
#define FGP_WRITE		0x00000008
#define FGP_NOFS		0x00000010
#define FGP_NOWAIT		0x00000020
#define FGP_FOR_MMAP		0x00000040
#define FGP_HEAD		0x00000080
#define FGP_ENTRY		0x00000100
#define FGP_STABLE		0x00000200

struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
		int fgp_flags, gfp_t gfp);
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
		int fgp_flags, gfp_t gfp);

/**
 * filemap_get_folio - Find and get a folio.
 * @mapping: The address_space to search.
 * @index: The page index.
 *
 * Looks up the page cache entry at @mapping & @index.  If a folio is
 * present, it is returned with an increased refcount.
 *
 * Otherwise, %NULL is returned.
 */
static inline struct folio *filemap_get_folio(struct address_space *mapping,
					pgoff_t index)
{
	return __filemap_get_folio(mapping, index, 0, 0);
}

/**
 * filemap_lock_folio - Find and lock a folio.
 * @mapping: The address_space to search.
 * @index: The page index.
 *
 * Looks up the page cache entry at @mapping & @index.  If a folio is
 * present, it is returned locked with an increased refcount.
 *
 * Context: May sleep.
 * Return: A folio or %NULL if there is no folio in the cache for this
 * index.  Will not return a shadow, swap or DAX entry.
 */
static inline struct folio *filemap_lock_folio(struct address_space *mapping,
					pgoff_t index)
{
	return __filemap_get_folio(mapping, index, FGP_LOCK, 0);
}

/**
 * find_get_page - find and get a page reference
 * @mapping: the address_space to search
 * @offset: the page index
 *
 * Looks up the page cache slot at @mapping & @offset.  If there is a
 * page cache page, it is returned with an increased refcount.
 *
 * Otherwise, %NULL is returned.
 */
static inline struct page *find_get_page(struct address_space *mapping,
					pgoff_t offset)
{
	return pagecache_get_page(mapping, offset, 0, 0);
}

static inline struct page *find_get_page_flags(struct address_space *mapping,
					pgoff_t offset, int fgp_flags)
{
	return pagecache_get_page(mapping, offset, fgp_flags, 0);
}

/**
 * find_lock_page - locate, pin and lock a pagecache page
 * @mapping: the address_space to search
 * @index: the page index
 *
 * Looks up the page cache entry at @mapping & @index.  If there is a
 * page cache page, it is returned locked and with an increased
 * refcount.
 *
 * Context: May sleep.
 * Return: A struct page or %NULL if there is no page in the cache for this
 * index.
 */
static inline struct page *find_lock_page(struct address_space *mapping,
					pgoff_t index)
{
	return pagecache_get_page(mapping, index, FGP_LOCK, 0);
}

/**
 * find_or_create_page - locate or add a pagecache page
 * @mapping: the page's address_space
 * @index: the page's index into the mapping
 * @gfp_mask: page allocation mode
 *
 * Looks up the page cache slot at @mapping & @offset.  If there is a
 * page cache page, it is returned locked and with an increased
 * refcount.
 *
 * If the page is not present, a new page is allocated using @gfp_mask
 * and added to the page cache and the VM's LRU list.  The page is
 * returned locked and with an increased refcount.
 *
 * On memory exhaustion, %NULL is returned.
 *
 * find_or_create_page() may sleep, even if @gfp_flags specifies an
 * atomic allocation!
 */
static inline struct page *find_or_create_page(struct address_space *mapping,
					pgoff_t index, gfp_t gfp_mask)
{
	return pagecache_get_page(mapping, index,
					FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
					gfp_mask);
}

/**
 * grab_cache_page_nowait - returns locked page at given index in given cache
 * @mapping: target address_space
 * @index: the page index
 *
 * Same as grab_cache_page(), but do not wait if the page is unavailable.
 * This is intended for speculative data generators, where the data can
 * be regenerated if the page couldn't be grabbed.  This routine should
 * be safe to call while holding the lock for another page.
 *
 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
 * and deadlock against the caller's locked page.
 */
static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
				pgoff_t index)
{
	return pagecache_get_page(mapping, index,
			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
			mapping_gfp_mask(mapping));
}

#define swapcache_index(folio)	__page_file_index(&(folio)->page)

/**
 * folio_index - File index of a folio.
 * @folio: The folio.
 *
 * For a folio which is either in the page cache or the swap cache,
 * return its index within the address_space it belongs to.  If you know
 * the page is definitely in the page cache, you can look at the folio's
 * index directly.
 *
 * Return: The index (offset in units of pages) of a folio in its file.
 */
static inline pgoff_t folio_index(struct folio *folio)
{
        if (unlikely(folio_test_swapcache(folio)))
                return swapcache_index(folio);
        return folio->index;
}

/**
 * folio_next_index - Get the index of the next folio.
 * @folio: The current folio.
 *
 * Return: The index of the folio which follows this folio in the file.
 */
static inline pgoff_t folio_next_index(struct folio *folio)
{
	return folio->index + folio_nr_pages(folio);
}

/**
 * folio_file_page - The page for a particular index.
 * @folio: The folio which contains this index.
 * @index: The index we want to look up.
 *
 * Sometimes after looking up a folio in the page cache, we need to
 * obtain the specific page for an index (eg a page fault).
 *
 * Return: The page containing the file data for this index.
 */
static inline struct page *folio_file_page(struct folio *folio, pgoff_t index)
{
	/* HugeTLBfs indexes the page cache in units of hpage_size */
	if (folio_test_hugetlb(folio))
		return &folio->page;
	return folio_page(folio, index & (folio_nr_pages(folio) - 1));
}

/**
 * folio_contains - Does this folio contain this index?
 * @folio: The folio.
 * @index: The page index within the file.
 *
 * Context: The caller should have the page locked in order to prevent
 * (eg) shmem from moving the page between the page cache and swap cache
 * and changing its index in the middle of the operation.
 * Return: true or false.
 */
static inline bool folio_contains(struct folio *folio, pgoff_t index)
{
	/* HugeTLBfs indexes the page cache in units of hpage_size */
	if (folio_test_hugetlb(folio))
		return folio->index == index;
	return index - folio_index(folio) < folio_nr_pages(folio);
}

/*
 * Given the page we found in the page cache, return the page corresponding
 * to this index in the file
 */
static inline struct page *find_subpage(struct page *head, pgoff_t index)
{
	/* HugeTLBfs wants the head page regardless */
	if (PageHuge(head))
		return head;

	return head + (index & (thp_nr_pages(head) - 1));
}

unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
			pgoff_t end, unsigned int nr_pages,
			struct page **pages);
unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
			       unsigned int nr_pages, struct page **pages);
unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
			pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
			struct page **pages);
static inline unsigned find_get_pages_tag(struct address_space *mapping,
			pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
			struct page **pages)
{
	return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
					nr_pages, pages);
}

struct page *grab_cache_page_write_begin(struct address_space *mapping,
			pgoff_t index, unsigned flags);

/*
 * Returns locked page at given index in given cache, creating it if needed.
 */
static inline struct page *grab_cache_page(struct address_space *mapping,
								pgoff_t index)
{
	return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
}

struct folio *read_cache_folio(struct address_space *, pgoff_t index,
		filler_t *filler, void *data);
struct page *read_cache_page(struct address_space *, pgoff_t index,
		filler_t *filler, void *data);
extern struct page * read_cache_page_gfp(struct address_space *mapping,
				pgoff_t index, gfp_t gfp_mask);
extern int read_cache_pages(struct address_space *mapping,
		struct list_head *pages, filler_t *filler, void *data);

static inline struct page *read_mapping_page(struct address_space *mapping,
				pgoff_t index, struct file *file)
{
	return read_cache_page(mapping, index, NULL, file);
}

static inline struct folio *read_mapping_folio(struct address_space *mapping,
				pgoff_t index, struct file *file)
{
	return read_cache_folio(mapping, index, NULL, file);
}

/*
 * Get index of the page within radix-tree (but not for hugetlb pages).
 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
 */
static inline pgoff_t page_to_index(struct page *page)
{
	struct page *head;

	if (likely(!PageTransTail(page)))
		return page->index;

	head = compound_head(page);
	/*
	 *  We don't initialize ->index for tail pages: calculate based on
	 *  head page
	 */
	return head->index + page - head;
}

extern pgoff_t hugetlb_basepage_index(struct page *page);

/*
 * Get the offset in PAGE_SIZE (even for hugetlb pages).
 * (TODO: hugetlb pages should have ->index in PAGE_SIZE)
 */
static inline pgoff_t page_to_pgoff(struct page *page)
{
	if (unlikely(PageHuge(page)))
		return hugetlb_basepage_index(page);
	return page_to_index(page);
}

/*
 * Return byte-offset into filesystem object for page.
 */
static inline loff_t page_offset(struct page *page)
{
	return ((loff_t)page->index) << PAGE_SHIFT;
}

static inline loff_t page_file_offset(struct page *page)
{
	return ((loff_t)page_index(page)) << PAGE_SHIFT;
}

/**
 * folio_pos - Returns the byte position of this folio in its file.
 * @folio: The folio.
 */
static inline loff_t folio_pos(struct folio *folio)
{
	return page_offset(&folio->page);
}

/**
 * folio_file_pos - Returns the byte position of this folio in its file.
 * @folio: The folio.
 *
 * This differs from folio_pos() for folios which belong to a swap file.
 * NFS is the only filesystem today which needs to use folio_file_pos().
 */
static inline loff_t folio_file_pos(struct folio *folio)
{
	return page_file_offset(&folio->page);
}

/*
 * Get the offset in PAGE_SIZE (even for hugetlb folios).
 * (TODO: hugetlb folios should have ->index in PAGE_SIZE)
 */
static inline pgoff_t folio_pgoff(struct folio *folio)
{
	if (unlikely(folio_test_hugetlb(folio)))
		return hugetlb_basepage_index(&folio->page);
	return folio->index;
}

extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
				     unsigned long address);

static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
					unsigned long address)
{
	pgoff_t pgoff;
	if (unlikely(is_vm_hugetlb_page(vma)))
		return linear_hugepage_index(vma, address);
	pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
	pgoff += vma->vm_pgoff;
	return pgoff;
}

struct wait_page_key {
	struct folio *folio;
	int bit_nr;
	int page_match;
};

struct wait_page_queue {
	struct folio *folio;
	int bit_nr;
	wait_queue_entry_t wait;
};

static inline bool wake_page_match(struct wait_page_queue *wait_page,
				  struct wait_page_key *key)
{
	if (wait_page->folio != key->folio)
	       return false;
	key->page_match = 1;

	if (wait_page->bit_nr != key->bit_nr)
		return false;

	return true;
}

void __folio_lock(struct folio *folio);
int __folio_lock_killable(struct folio *folio);
bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
				unsigned int flags);
void unlock_page(struct page *page);
void folio_unlock(struct folio *folio);

static inline bool folio_trylock(struct folio *folio)
{
	return likely(!test_and_set_bit_lock(PG_locked, folio_flags(folio, 0)));
}

/*
 * Return true if the page was successfully locked
 */
static inline int trylock_page(struct page *page)
{
	return folio_trylock(page_folio(page));
}

static inline void folio_lock(struct folio *folio)
{
	might_sleep();
	if (!folio_trylock(folio))
		__folio_lock(folio);
}

/*
 * lock_page may only be called if we have the page's inode pinned.
 */
static inline void lock_page(struct page *page)
{
	struct folio *folio;
	might_sleep();

	folio = page_folio(page);
	if (!folio_trylock(folio))
		__folio_lock(folio);
}

static inline int folio_lock_killable(struct folio *folio)
{
	might_sleep();
	if (!folio_trylock(folio))
		return __folio_lock_killable(folio);
	return 0;
}

/*
 * lock_page_killable is like lock_page but can be interrupted by fatal
 * signals.  It returns 0 if it locked the page and -EINTR if it was
 * killed while waiting.
 */
static inline int lock_page_killable(struct page *page)
{
	return folio_lock_killable(page_folio(page));
}

/*
 * lock_page_or_retry - Lock the page, unless this would block and the
 * caller indicated that it can handle a retry.
 *
 * Return value and mmap_lock implications depend on flags; see
 * __folio_lock_or_retry().
 */
static inline bool lock_page_or_retry(struct page *page, struct mm_struct *mm,
				     unsigned int flags)
{
	struct folio *folio;
	might_sleep();

	folio = page_folio(page);
	return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
}

/*
 * This is exported only for folio_wait_locked/folio_wait_writeback, etc.,
 * and should not be used directly.
 */
void folio_wait_bit(struct folio *folio, int bit_nr);
int folio_wait_bit_killable(struct folio *folio, int bit_nr);

/* 
 * Wait for a folio to be unlocked.
 *
 * This must be called with the caller "holding" the folio,
 * ie with increased "page->count" so that the folio won't
 * go away during the wait..
 */
static inline void folio_wait_locked(struct folio *folio)
{
	if (folio_test_locked(folio))
		folio_wait_bit(folio, PG_locked);
}

static inline int folio_wait_locked_killable(struct folio *folio)
{
	if (!folio_test_locked(folio))
		return 0;
	return folio_wait_bit_killable(folio, PG_locked);
}

static inline void wait_on_page_locked(struct page *page)
{
	folio_wait_locked(page_folio(page));
}

static inline int wait_on_page_locked_killable(struct page *page)
{
	return folio_wait_locked_killable(page_folio(page));
}

int folio_put_wait_locked(struct folio *folio, int state);
void wait_on_page_writeback(struct page *page);
void folio_wait_writeback(struct folio *folio);
int folio_wait_writeback_killable(struct folio *folio);
void end_page_writeback(struct page *page);
void folio_end_writeback(struct folio *folio);
void wait_for_stable_page(struct page *page);
void folio_wait_stable(struct folio *folio);
void __folio_mark_dirty(struct folio *folio, struct address_space *, int warn);
static inline void __set_page_dirty(struct page *page,
		struct address_space *mapping, int warn)
{
	__folio_mark_dirty(page_folio(page), mapping, warn);
}
void folio_account_cleaned(struct folio *folio, struct address_space *mapping,
			  struct bdi_writeback *wb);
void __folio_cancel_dirty(struct folio *folio);
static inline void folio_cancel_dirty(struct folio *folio)
{
	/* Avoid atomic ops, locking, etc. when not actually needed. */
	if (folio_test_dirty(folio))
		__folio_cancel_dirty(folio);
}
static inline void cancel_dirty_page(struct page *page)
{
	folio_cancel_dirty(page_folio(page));
}
bool folio_clear_dirty_for_io(struct folio *folio);
bool clear_page_dirty_for_io(struct page *page);
void folio_invalidate(struct folio *folio, size_t offset, size_t length);
int __must_check folio_write_one(struct folio *folio);
static inline int __must_check write_one_page(struct page *page)
{
	return folio_write_one(page_folio(page));
}

int __set_page_dirty_nobuffers(struct page *page);
bool noop_dirty_folio(struct address_space *mapping, struct folio *folio);

void page_endio(struct page *page, bool is_write, int err);

void folio_end_private_2(struct folio *folio);
void folio_wait_private_2(struct folio *folio);
int folio_wait_private_2_killable(struct folio *folio);

/*
 * Add an arbitrary waiter to a page's wait queue
 */
void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter);

/*
 * Fault in userspace address range.
 */
size_t fault_in_writeable(char __user *uaddr, size_t size);
size_t fault_in_safe_writeable(const char __user *uaddr, size_t size);
size_t fault_in_readable(const char __user *uaddr, size_t size);

int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
		pgoff_t index, gfp_t gfp);
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
		pgoff_t index, gfp_t gfp);
int filemap_add_folio(struct address_space *mapping, struct folio *folio,
		pgoff_t index, gfp_t gfp);
void filemap_remove_folio(struct folio *folio);
void delete_from_page_cache(struct page *page);
void __filemap_remove_folio(struct folio *folio, void *shadow);
static inline void __delete_from_page_cache(struct page *page, void *shadow)
{
	__filemap_remove_folio(page_folio(page), shadow);
}
void replace_page_cache_page(struct page *old, struct page *new);
void delete_from_page_cache_batch(struct address_space *mapping,
				  struct folio_batch *fbatch);
int try_to_release_page(struct page *page, gfp_t gfp);
bool filemap_release_folio(struct folio *folio, gfp_t gfp);
loff_t mapping_seek_hole_data(struct address_space *, loff_t start, loff_t end,
		int whence);

/*
 * Like add_to_page_cache_locked, but used to add newly allocated pages:
 * the page is new, so we can just run __SetPageLocked() against it.
 */
static inline int add_to_page_cache(struct page *page,
		struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
{
	int error;

	__SetPageLocked(page);
	error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
	if (unlikely(error))
		__ClearPageLocked(page);
	return error;
}

/* Must be non-static for BPF error injection */
int __filemap_add_folio(struct address_space *mapping, struct folio *folio,
		pgoff_t index, gfp_t gfp, void **shadowp);

bool filemap_range_has_writeback(struct address_space *mapping,
				 loff_t start_byte, loff_t end_byte);

/**
 * filemap_range_needs_writeback - check if range potentially needs writeback
 * @mapping:           address space within which to check
 * @start_byte:        offset in bytes where the range starts
 * @end_byte:          offset in bytes where the range ends (inclusive)
 *
 * Find at least one page in the range supplied, usually used to check if
 * direct writing in this range will trigger a writeback. Used by O_DIRECT
 * read/write with IOCB_NOWAIT, to see if the caller needs to do
 * filemap_write_and_wait_range() before proceeding.
 *
 * Return: %true if the caller should do filemap_write_and_wait_range() before
 * doing O_DIRECT to a page in this range, %false otherwise.
 */
static inline bool filemap_range_needs_writeback(struct address_space *mapping,
						 loff_t start_byte,
						 loff_t end_byte)
{
	if (!mapping->nrpages)
		return false;
	if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
	    !mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
		return false;
	return filemap_range_has_writeback(mapping, start_byte, end_byte);
}

/**
 * struct readahead_control - Describes a readahead request.
 *
 * A readahead request is for consecutive pages.  Filesystems which
 * implement the ->readahead method should call readahead_page() or
 * readahead_page_batch() in a loop and attempt to start I/O against
 * each page in the request.
 *
 * Most of the fields in this struct are private and should be accessed
 * by the functions below.
 *
 * @file: The file, used primarily by network filesystems for authentication.
 *	  May be NULL if invoked internally by the filesystem.
 * @mapping: Readahead this filesystem object.
 * @ra: File readahead state.  May be NULL.
 */
struct readahead_control {
	struct file *file;
	struct address_space *mapping;
	struct file_ra_state *ra;
/* private: use the readahead_* accessors instead */
	pgoff_t _index;
	unsigned int _nr_pages;
	unsigned int _batch_count;
};

#define DEFINE_READAHEAD(ractl, f, r, m, i)				\
	struct readahead_control ractl = {				\
		.file = f,						\
		.mapping = m,						\
		.ra = r,						\
		._index = i,						\
	}

#define VM_READAHEAD_PAGES	(SZ_128K / PAGE_SIZE)

void page_cache_ra_unbounded(struct readahead_control *,
		unsigned long nr_to_read, unsigned long lookahead_count);
void page_cache_sync_ra(struct readahead_control *, unsigned long req_count);
void page_cache_async_ra(struct readahead_control *, struct folio *,
		unsigned long req_count);
void readahead_expand(struct readahead_control *ractl,
		      loff_t new_start, size_t new_len);

/**
 * page_cache_sync_readahead - generic file readahead
 * @mapping: address_space which holds the pagecache and I/O vectors
 * @ra: file_ra_state which holds the readahead state
 * @file: Used by the filesystem for authentication.
 * @index: Index of first page to be read.
 * @req_count: Total number of pages being read by the caller.
 *
 * page_cache_sync_readahead() should be called when a cache miss happened:
 * it will submit the read.  The readahead logic may decide to piggyback more
 * pages onto the read request if access patterns suggest it will improve
 * performance.
 */
static inline
void page_cache_sync_readahead(struct address_space *mapping,
		struct file_ra_state *ra, struct file *file, pgoff_t index,
		unsigned long req_count)
{
	DEFINE_READAHEAD(ractl, file, ra, mapping, index);
	page_cache_sync_ra(&ractl, req_count);
}

/**
 * page_cache_async_readahead - file readahead for marked pages
 * @mapping: address_space which holds the pagecache and I/O vectors
 * @ra: file_ra_state which holds the readahead state
 * @file: Used by the filesystem for authentication.
 * @page: The page at @index which triggered the readahead call.
 * @index: Index of first page to be read.
 * @req_count: Total number of pages being read by the caller.
 *
 * page_cache_async_readahead() should be called when a page is used which
 * is marked as PageReadahead; this is a marker to suggest that the application
 * has used up enough of the readahead window that we should start pulling in
 * more pages.
 */
static inline
void page_cache_async_readahead(struct address_space *mapping,
		struct file_ra_state *ra, struct file *file,
		struct page *page, pgoff_t index, unsigned long req_count)
{
	DEFINE_READAHEAD(ractl, file, ra, mapping, index);
	page_cache_async_ra(&ractl, page_folio(page), req_count);
}

static inline struct folio *__readahead_folio(struct readahead_control *ractl)
{
	struct folio *folio;

	BUG_ON(ractl->_batch_count > ractl->_nr_pages);
	ractl->_nr_pages -= ractl->_batch_count;
	ractl->_index += ractl->_batch_count;

	if (!ractl->_nr_pages) {
		ractl->_batch_count = 0;
		return NULL;
	}

	folio = xa_load(&ractl->mapping->i_pages, ractl->_index);
	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
	ractl->_batch_count = folio_nr_pages(folio);

	return folio;
}

/**
 * readahead_page - Get the next page to read.
 * @ractl: The current readahead request.
 *
 * Context: The page is locked and has an elevated refcount.  The caller
 * should decreases the refcount once the page has been submitted for I/O
 * and unlock the page once all I/O to that page has completed.
 * Return: A pointer to the next page, or %NULL if we are done.
 */
static inline struct page *readahead_page(struct readahead_control *ractl)
{
	struct folio *folio = __readahead_folio(ractl);

	return &folio->page;
}

/**
 * readahead_folio - Get the next folio to read.
 * @ractl: The current readahead request.
 *
 * Context: The folio is locked.  The caller should unlock the folio once
 * all I/O to that folio has completed.
 * Return: A pointer to the next folio, or %NULL if we are done.
 */
static inline struct folio *readahead_folio(struct readahead_control *ractl)
{
	struct folio *folio = __readahead_folio(ractl);

	if (folio)
		folio_put(folio);
	return folio;
}

static inline unsigned int __readahead_batch(struct readahead_control *rac,
		struct page **array, unsigned int array_sz)
{
	unsigned int i = 0;
	XA_STATE(xas, &rac->mapping->i_pages, 0);
	struct page *page;

	BUG_ON(rac->_batch_count > rac->_nr_pages);
	rac->_nr_pages -= rac->_batch_count;
	rac->_index += rac->_batch_count;
	rac->_batch_count = 0;

	xas_set(&xas, rac->_index);
	rcu_read_lock();
	xas_for_each(&xas, page, rac->_index + rac->_nr_pages - 1) {
		if (xas_retry(&xas, page))
			continue;
		VM_BUG_ON_PAGE(!PageLocked(page), page);
		VM_BUG_ON_PAGE(PageTail(page), page);
		array[i++] = page;
		rac->_batch_count += thp_nr_pages(page);
		if (i == array_sz)
			break;
	}
	rcu_read_unlock();

	return i;
}

/**
 * readahead_page_batch - Get a batch of pages to read.
 * @rac: The current readahead request.
 * @array: An array of pointers to struct page.
 *
 * Context: The pages are locked and have an elevated refcount.  The caller
 * should decreases the refcount once the page has been submitted for I/O
 * and unlock the page once all I/O to that page has completed.
 * Return: The number of pages placed in the array.  0 indicates the request
 * is complete.
 */
#define readahead_page_batch(rac, array)				\
	__readahead_batch(rac, array, ARRAY_SIZE(array))

/**
 * readahead_pos - The byte offset into the file of this readahead request.
 * @rac: The readahead request.
 */
static inline loff_t readahead_pos(struct readahead_control *rac)
{
	return (loff_t)rac->_index * PAGE_SIZE;
}

/**
 * readahead_length - The number of bytes in this readahead request.
 * @rac: The readahead request.
 */
static inline size_t readahead_length(struct readahead_control *rac)
{
	return rac->_nr_pages * PAGE_SIZE;
}

/**
 * readahead_index - The index of the first page in this readahead request.
 * @rac: The readahead request.
 */
static inline pgoff_t readahead_index(struct readahead_control *rac)
{
	return rac->_index;
}

/**
 * readahead_count - The number of pages in this readahead request.
 * @rac: The readahead request.
 */
static inline unsigned int readahead_count(struct readahead_control *rac)
{
	return rac->_nr_pages;
}

/**
 * readahead_batch_length - The number of bytes in the current batch.
 * @rac: The readahead request.
 */
static inline size_t readahead_batch_length(struct readahead_control *rac)
{
	return rac->_batch_count * PAGE_SIZE;
}

static inline unsigned long dir_pages(struct inode *inode)
{
	return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
			       PAGE_SHIFT;
}

/**
 * folio_mkwrite_check_truncate - check if folio was truncated
 * @folio: the folio to check
 * @inode: the inode to check the folio against
 *
 * Return: the number of bytes in the folio up to EOF,
 * or -EFAULT if the folio was truncated.
 */
static inline ssize_t folio_mkwrite_check_truncate(struct folio *folio,
					      struct inode *inode)
{
	loff_t size = i_size_read(inode);
	pgoff_t index = size >> PAGE_SHIFT;
	size_t offset = offset_in_folio(folio, size);

	if (!folio->mapping)
		return -EFAULT;

	/* folio is wholly inside EOF */
	if (folio_next_index(folio) - 1 < index)
		return folio_size(folio);
	/* folio is wholly past EOF */
	if (folio->index > index || !offset)
		return -EFAULT;
	/* folio is partially inside EOF */
	return offset;
}

/**
 * page_mkwrite_check_truncate - check if page was truncated
 * @page: the page to check
 * @inode: the inode to check the page against
 *
 * Returns the number of bytes in the page up to EOF,
 * or -EFAULT if the page was truncated.
 */
static inline int page_mkwrite_check_truncate(struct page *page,
					      struct inode *inode)
{
	loff_t size = i_size_read(inode);
	pgoff_t index = size >> PAGE_SHIFT;
	int offset = offset_in_page(size);

	if (page->mapping != inode->i_mapping)
		return -EFAULT;

	/* page is wholly inside EOF */
	if (page->index < index)
		return PAGE_SIZE;
	/* page is wholly past EOF */
	if (page->index > index || !offset)
		return -EFAULT;
	/* page is partially inside EOF */
	return offset;
}

/**
 * i_blocks_per_folio - How many blocks fit in this folio.
 * @inode: The inode which contains the blocks.
 * @folio: The folio.
 *
 * If the block size is larger than the size of this folio, return zero.
 *
 * Context: The caller should hold a refcount on the folio to prevent it
 * from being split.
 * Return: The number of filesystem blocks covered by this folio.
 */
static inline
unsigned int i_blocks_per_folio(struct inode *inode, struct folio *folio)
{
	return folio_size(folio) >> inode->i_blkbits;
}

static inline
unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
{
	return i_blocks_per_folio(inode, page_folio(page));
}
#endif /* _LINUX_PAGEMAP_H */