summaryrefslogtreecommitdiff
path: root/fs/read_write.c
blob: acfd3dc63d5704474d4701cec0f46309ebf8e36a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
/*
 *  linux/fs/read_write.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sched/xacct.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/splice.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/fs.h>
#include "internal.h"

#include <linux/uaccess.h>
#include <asm/unistd.h>

const struct file_operations generic_ro_fops = {
	.llseek		= generic_file_llseek,
	.read_iter	= generic_file_read_iter,
	.mmap		= generic_file_readonly_mmap,
	.splice_read	= generic_file_splice_read,
};

EXPORT_SYMBOL(generic_ro_fops);

static inline int unsigned_offsets(struct file *file)
{
	return file->f_mode & FMODE_UNSIGNED_OFFSET;
}

/**
 * vfs_setpos - update the file offset for lseek
 * @file:	file structure in question
 * @offset:	file offset to seek to
 * @maxsize:	maximum file size
 *
 * This is a low-level filesystem helper for updating the file offset to
 * the value specified by @offset if the given offset is valid and it is
 * not equal to the current file offset.
 *
 * Return the specified offset on success and -EINVAL on invalid offset.
 */
loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
{
	if (offset < 0 && !unsigned_offsets(file))
		return -EINVAL;
	if (offset > maxsize)
		return -EINVAL;

	if (offset != file->f_pos) {
		file->f_pos = offset;
		file->f_version = 0;
	}
	return offset;
}
EXPORT_SYMBOL(vfs_setpos);

/**
 * generic_file_llseek_size - generic llseek implementation for regular files
 * @file:	file structure to seek on
 * @offset:	file offset to seek to
 * @whence:	type of seek
 * @size:	max size of this file in file system
 * @eof:	offset used for SEEK_END position
 *
 * This is a variant of generic_file_llseek that allows passing in a custom
 * maximum file size and a custom EOF position, for e.g. hashed directories
 *
 * Synchronization:
 * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms)
 * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
 * read/writes behave like SEEK_SET against seeks.
 */
loff_t
generic_file_llseek_size(struct file *file, loff_t offset, int whence,
		loff_t maxsize, loff_t eof)
{
	switch (whence) {
	case SEEK_END:
		offset += eof;
		break;
	case SEEK_CUR:
		/*
		 * Here we special-case the lseek(fd, 0, SEEK_CUR)
		 * position-querying operation.  Avoid rewriting the "same"
		 * f_pos value back to the file because a concurrent read(),
		 * write() or lseek() might have altered it
		 */
		if (offset == 0)
			return file->f_pos;
		/*
		 * f_lock protects against read/modify/write race with other
		 * SEEK_CURs. Note that parallel writes and reads behave
		 * like SEEK_SET.
		 */
		spin_lock(&file->f_lock);
		offset = vfs_setpos(file, file->f_pos + offset, maxsize);
		spin_unlock(&file->f_lock);
		return offset;
	case SEEK_DATA:
		/*
		 * In the generic case the entire file is data, so as long as
		 * offset isn't at the end of the file then the offset is data.
		 */
		if (offset >= eof)
			return -ENXIO;
		break;
	case SEEK_HOLE:
		/*
		 * There is a virtual hole at the end of the file, so as long as
		 * offset isn't i_size or larger, return i_size.
		 */
		if (offset >= eof)
			return -ENXIO;
		offset = eof;
		break;
	}

	return vfs_setpos(file, offset, maxsize);
}
EXPORT_SYMBOL(generic_file_llseek_size);

/**
 * generic_file_llseek - generic llseek implementation for regular files
 * @file:	file structure to seek on
 * @offset:	file offset to seek to
 * @whence:	type of seek
 *
 * This is a generic implemenation of ->llseek useable for all normal local
 * filesystems.  It just updates the file offset to the value specified by
 * @offset and @whence.
 */
loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
{
	struct inode *inode = file->f_mapping->host;

	return generic_file_llseek_size(file, offset, whence,
					inode->i_sb->s_maxbytes,
					i_size_read(inode));
}
EXPORT_SYMBOL(generic_file_llseek);

/**
 * fixed_size_llseek - llseek implementation for fixed-sized devices
 * @file:	file structure to seek on
 * @offset:	file offset to seek to
 * @whence:	type of seek
 * @size:	size of the file
 *
 */
loff_t fixed_size_llseek(struct file *file, loff_t offset, int whence, loff_t size)
{
	switch (whence) {
	case SEEK_SET: case SEEK_CUR: case SEEK_END:
		return generic_file_llseek_size(file, offset, whence,
						size, size);
	default:
		return -EINVAL;
	}
}
EXPORT_SYMBOL(fixed_size_llseek);

/**
 * no_seek_end_llseek - llseek implementation for fixed-sized devices
 * @file:	file structure to seek on
 * @offset:	file offset to seek to
 * @whence:	type of seek
 *
 */
loff_t no_seek_end_llseek(struct file *file, loff_t offset, int whence)
{
	switch (whence) {
	case SEEK_SET: case SEEK_CUR:
		return generic_file_llseek_size(file, offset, whence,
						OFFSET_MAX, 0);
	default:
		return -EINVAL;
	}
}
EXPORT_SYMBOL(no_seek_end_llseek);

/**
 * no_seek_end_llseek_size - llseek implementation for fixed-sized devices
 * @file:	file structure to seek on
 * @offset:	file offset to seek to
 * @whence:	type of seek
 * @size:	maximal offset allowed
 *
 */
loff_t no_seek_end_llseek_size(struct file *file, loff_t offset, int whence, loff_t size)
{
	switch (whence) {
	case SEEK_SET: case SEEK_CUR:
		return generic_file_llseek_size(file, offset, whence,
						size, 0);
	default:
		return -EINVAL;
	}
}
EXPORT_SYMBOL(no_seek_end_llseek_size);

/**
 * noop_llseek - No Operation Performed llseek implementation
 * @file:	file structure to seek on
 * @offset:	file offset to seek to
 * @whence:	type of seek
 *
 * This is an implementation of ->llseek useable for the rare special case when
 * userspace expects the seek to succeed but the (device) file is actually not
 * able to perform the seek. In this case you use noop_llseek() instead of
 * falling back to the default implementation of ->llseek.
 */
loff_t noop_llseek(struct file *file, loff_t offset, int whence)
{
	return file->f_pos;
}
EXPORT_SYMBOL(noop_llseek);

loff_t no_llseek(struct file *file, loff_t offset, int whence)
{
	return -ESPIPE;
}
EXPORT_SYMBOL(no_llseek);

loff_t default_llseek(struct file *file, loff_t offset, int whence)
{
	struct inode *inode = file_inode(file);
	loff_t retval;

	inode_lock(inode);
	switch (whence) {
		case SEEK_END:
			offset += i_size_read(inode);
			break;
		case SEEK_CUR:
			if (offset == 0) {
				retval = file->f_pos;
				goto out;
			}
			offset += file->f_pos;
			break;
		case SEEK_DATA:
			/*
			 * In the generic case the entire file is data, so as
			 * long as offset isn't at the end of the file then the
			 * offset is data.
			 */
			if (offset >= inode->i_size) {
				retval = -ENXIO;
				goto out;
			}
			break;
		case SEEK_HOLE:
			/*
			 * There is a virtual hole at the end of the file, so
			 * as long as offset isn't i_size or larger, return
			 * i_size.
			 */
			if (offset >= inode->i_size) {
				retval = -ENXIO;
				goto out;
			}
			offset = inode->i_size;
			break;
	}
	retval = -EINVAL;
	if (offset >= 0 || unsigned_offsets(file)) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
			file->f_version = 0;
		}
		retval = offset;
	}
out:
	inode_unlock(inode);
	return retval;
}
EXPORT_SYMBOL(default_llseek);

loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
{
	loff_t (*fn)(struct file *, loff_t, int);

	fn = no_llseek;
	if (file->f_mode & FMODE_LSEEK) {
		if (file->f_op->llseek)
			fn = file->f_op->llseek;
	}
	return fn(file, offset, whence);
}
EXPORT_SYMBOL(vfs_llseek);

SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
{
	off_t retval;
	struct fd f = fdget_pos(fd);
	if (!f.file)
		return -EBADF;

	retval = -EINVAL;
	if (whence <= SEEK_MAX) {
		loff_t res = vfs_llseek(f.file, offset, whence);
		retval = res;
		if (res != (loff_t)retval)
			retval = -EOVERFLOW;	/* LFS: should only happen on 32 bit platforms */
	}
	fdput_pos(f);
	return retval;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence)
{
	return sys_lseek(fd, offset, whence);
}
#endif

#ifdef __ARCH_WANT_SYS_LLSEEK
SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
		unsigned long, offset_low, loff_t __user *, result,
		unsigned int, whence)
{
	int retval;
	struct fd f = fdget_pos(fd);
	loff_t offset;

	if (!f.file)
		return -EBADF;

	retval = -EINVAL;
	if (whence > SEEK_MAX)
		goto out_putf;

	offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
			whence);

	retval = (int)offset;
	if (offset >= 0) {
		retval = -EFAULT;
		if (!copy_to_user(result, &offset, sizeof(offset)))
			retval = 0;
	}
out_putf:
	fdput_pos(f);
	return retval;
}
#endif

int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count)
{
	struct inode *inode;
	loff_t pos;
	int retval = -EINVAL;

	inode = file_inode(file);
	if (unlikely((ssize_t) count < 0))
		return retval;
	pos = *ppos;
	if (unlikely(pos < 0)) {
		if (!unsigned_offsets(file))
			return retval;
		if (count >= -pos) /* both values are in 0..LLONG_MAX */
			return -EOVERFLOW;
	} else if (unlikely((loff_t) (pos + count) < 0)) {
		if (!unsigned_offsets(file))
			return retval;
	}

	if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
		retval = locks_mandatory_area(inode, file, pos, pos + count - 1,
				read_write == READ ? F_RDLCK : F_WRLCK);
		if (retval < 0)
			return retval;
	}
	return security_file_permission(file,
				read_write == READ ? MAY_READ : MAY_WRITE);
}

static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
{
	struct iovec iov = { .iov_base = buf, .iov_len = len };
	struct kiocb kiocb;
	struct iov_iter iter;
	ssize_t ret;

	init_sync_kiocb(&kiocb, filp);
	kiocb.ki_pos = *ppos;
	iov_iter_init(&iter, READ, &iov, 1, len);

	ret = call_read_iter(filp, &kiocb, &iter);
	BUG_ON(ret == -EIOCBQUEUED);
	*ppos = kiocb.ki_pos;
	return ret;
}

ssize_t __vfs_read(struct file *file, char __user *buf, size_t count,
		   loff_t *pos)
{
	if (file->f_op->read)
		return file->f_op->read(file, buf, count, pos);
	else if (file->f_op->read_iter)
		return new_sync_read(file, buf, count, pos);
	else
		return -EINVAL;
}
EXPORT_SYMBOL(__vfs_read);

ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
{
	ssize_t ret;

	if (!(file->f_mode & FMODE_READ))
		return -EBADF;
	if (!(file->f_mode & FMODE_CAN_READ))
		return -EINVAL;
	if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
		return -EFAULT;

	ret = rw_verify_area(READ, file, pos, count);
	if (!ret) {
		if (count > MAX_RW_COUNT)
			count =  MAX_RW_COUNT;
		ret = __vfs_read(file, buf, count, pos);
		if (ret > 0) {
			fsnotify_access(file);
			add_rchar(current, ret);
		}
		inc_syscr(current);
	}

	return ret;
}

EXPORT_SYMBOL(vfs_read);

static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
	struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
	struct kiocb kiocb;
	struct iov_iter iter;
	ssize_t ret;

	init_sync_kiocb(&kiocb, filp);
	kiocb.ki_pos = *ppos;
	iov_iter_init(&iter, WRITE, &iov, 1, len);

	ret = call_write_iter(filp, &kiocb, &iter);
	BUG_ON(ret == -EIOCBQUEUED);
	if (ret > 0)
		*ppos = kiocb.ki_pos;
	return ret;
}

ssize_t __vfs_write(struct file *file, const char __user *p, size_t count,
		    loff_t *pos)
{
	if (file->f_op->write)
		return file->f_op->write(file, p, count, pos);
	else if (file->f_op->write_iter)
		return new_sync_write(file, p, count, pos);
	else
		return -EINVAL;
}
EXPORT_SYMBOL(__vfs_write);

ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t *pos)
{
	mm_segment_t old_fs;
	const char __user *p;
	ssize_t ret;

	if (!(file->f_mode & FMODE_CAN_WRITE))
		return -EINVAL;

	old_fs = get_fs();
	set_fs(get_ds());
	p = (__force const char __user *)buf;
	if (count > MAX_RW_COUNT)
		count =  MAX_RW_COUNT;
	ret = __vfs_write(file, p, count, pos);
	set_fs(old_fs);
	if (ret > 0) {
		fsnotify_modify(file);
		add_wchar(current, ret);
	}
	inc_syscw(current);
	return ret;
}

EXPORT_SYMBOL(__kernel_write);

ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
{
	ssize_t ret;

	if (!(file->f_mode & FMODE_WRITE))
		return -EBADF;
	if (!(file->f_mode & FMODE_CAN_WRITE))
		return -EINVAL;
	if (unlikely(!access_ok(VERIFY_READ, buf, count)))
		return -EFAULT;

	ret = rw_verify_area(WRITE, file, pos, count);
	if (!ret) {
		if (count > MAX_RW_COUNT)
			count =  MAX_RW_COUNT;
		file_start_write(file);
		ret = __vfs_write(file, buf, count, pos);
		if (ret > 0) {
			fsnotify_modify(file);
			add_wchar(current, ret);
		}
		inc_syscw(current);
		file_end_write(file);
	}

	return ret;
}

EXPORT_SYMBOL(vfs_write);

static inline loff_t file_pos_read(struct file *file)
{
	return file->f_pos;
}

static inline void file_pos_write(struct file *file, loff_t pos)
{
	file->f_pos = pos;
}

SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
{
	struct fd f = fdget_pos(fd);
	ssize_t ret = -EBADF;

	if (f.file) {
		loff_t pos = file_pos_read(f.file);
		ret = vfs_read(f.file, buf, count, &pos);
		if (ret >= 0)
			file_pos_write(f.file, pos);
		fdput_pos(f);
	}
	return ret;
}

SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
		size_t, count)
{
	struct fd f = fdget_pos(fd);
	ssize_t ret = -EBADF;

	if (f.file) {
		loff_t pos = file_pos_read(f.file);
		ret = vfs_write(f.file, buf, count, &pos);
		if (ret >= 0)
			file_pos_write(f.file, pos);
		fdput_pos(f);
	}

	return ret;
}

SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
			size_t, count, loff_t, pos)
{
	struct fd f;
	ssize_t ret = -EBADF;

	if (pos < 0)
		return -EINVAL;

	f = fdget(fd);
	if (f.file) {
		ret = -ESPIPE;
		if (f.file->f_mode & FMODE_PREAD)
			ret = vfs_read(f.file, buf, count, &pos);
		fdput(f);
	}

	return ret;
}

SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
			 size_t, count, loff_t, pos)
{
	struct fd f;
	ssize_t ret = -EBADF;

	if (pos < 0)
		return -EINVAL;

	f = fdget(fd);
	if (f.file) {
		ret = -ESPIPE;
		if (f.file->f_mode & FMODE_PWRITE)  
			ret = vfs_write(f.file, buf, count, &pos);
		fdput(f);
	}

	return ret;
}

/*
 * Reduce an iovec's length in-place.  Return the resulting number of segments
 */
unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
{
	unsigned long seg = 0;
	size_t len = 0;

	while (seg < nr_segs) {
		seg++;
		if (len + iov->iov_len >= to) {
			iov->iov_len = to - len;
			break;
		}
		len += iov->iov_len;
		iov++;
	}
	return seg;
}
EXPORT_SYMBOL(iov_shorten);

static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
		loff_t *ppos, int type, int flags)
{
	struct kiocb kiocb;
	ssize_t ret;

	if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC))
		return -EOPNOTSUPP;

	init_sync_kiocb(&kiocb, filp);
	if (flags & RWF_HIPRI)
		kiocb.ki_flags |= IOCB_HIPRI;
	if (flags & RWF_DSYNC)
		kiocb.ki_flags |= IOCB_DSYNC;
	if (flags & RWF_SYNC)
		kiocb.ki_flags |= (IOCB_DSYNC | IOCB_SYNC);
	kiocb.ki_pos = *ppos;

	if (type == READ)
		ret = call_read_iter(filp, &kiocb, iter);
	else
		ret = call_write_iter(filp, &kiocb, iter);
	BUG_ON(ret == -EIOCBQUEUED);
	*ppos = kiocb.ki_pos;
	return ret;
}

/* Do it by hand, with file-ops */
static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
		loff_t *ppos, int type, int flags)
{
	ssize_t ret = 0;

	if (flags & ~RWF_HIPRI)
		return -EOPNOTSUPP;

	while (iov_iter_count(iter)) {
		struct iovec iovec = iov_iter_iovec(iter);
		ssize_t nr;

		if (type == READ) {
			nr = filp->f_op->read(filp, iovec.iov_base,
					      iovec.iov_len, ppos);
		} else {
			nr = filp->f_op->write(filp, iovec.iov_base,
					       iovec.iov_len, ppos);
		}

		if (nr < 0) {
			if (!ret)
				ret = nr;
			break;
		}
		ret += nr;
		if (nr != iovec.iov_len)
			break;
		iov_iter_advance(iter, nr);
	}

	return ret;
}

/* A write operation does a read from user space and vice versa */
#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)

/**
 * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
 *     into the kernel and check that it is valid.
 *
 * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
 * @uvector: Pointer to the userspace array.
 * @nr_segs: Number of elements in userspace array.
 * @fast_segs: Number of elements in @fast_pointer.
 * @fast_pointer: Pointer to (usually small on-stack) kernel array.
 * @ret_pointer: (output parameter) Pointer to a variable that will point to
 *     either @fast_pointer, a newly allocated kernel array, or NULL,
 *     depending on which array was used.
 *
 * This function copies an array of &struct iovec of @nr_segs from
 * userspace into the kernel and checks that each element is valid (e.g.
 * it does not point to a kernel address or cause overflow by being too
 * large, etc.).
 *
 * As an optimization, the caller may provide a pointer to a small
 * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
 * (the size of this array, or 0 if unused, should be given in @fast_segs).
 *
 * @ret_pointer will always point to the array that was used, so the
 * caller must take care not to call kfree() on it e.g. in case the
 * @fast_pointer array was used and it was allocated on the stack.
 *
 * Return: The total number of bytes covered by the iovec array on success
 *   or a negative error code on error.
 */
ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
			      unsigned long nr_segs, unsigned long fast_segs,
			      struct iovec *fast_pointer,
			      struct iovec **ret_pointer)
{
	unsigned long seg;
	ssize_t ret;
	struct iovec *iov = fast_pointer;

	/*
	 * SuS says "The readv() function *may* fail if the iovcnt argument
	 * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
	 * traditionally returned zero for zero segments, so...
	 */
	if (nr_segs == 0) {
		ret = 0;
		goto out;
	}

	/*
	 * First get the "struct iovec" from user memory and
	 * verify all the pointers
	 */
	if (nr_segs > UIO_MAXIOV) {
		ret = -EINVAL;
		goto out;
	}
	if (nr_segs > fast_segs) {
		iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
		if (iov == NULL) {
			ret = -ENOMEM;
			goto out;
		}
	}
	if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
		ret = -EFAULT;
		goto out;
	}

	/*
	 * According to the Single Unix Specification we should return EINVAL
	 * if an element length is < 0 when cast to ssize_t or if the
	 * total length would overflow the ssize_t return value of the
	 * system call.
	 *
	 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
	 * overflow case.
	 */
	ret = 0;
	for (seg = 0; seg < nr_segs; seg++) {
		void __user *buf = iov[seg].iov_base;
		ssize_t len = (ssize_t)iov[seg].iov_len;

		/* see if we we're about to use an invalid len or if
		 * it's about to overflow ssize_t */
		if (len < 0) {
			ret = -EINVAL;
			goto out;
		}
		if (type >= 0
		    && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
			ret = -EFAULT;
			goto out;
		}
		if (len > MAX_RW_COUNT - ret) {
			len = MAX_RW_COUNT - ret;
			iov[seg].iov_len = len;
		}
		ret += len;
	}
out:
	*ret_pointer = iov;
	return ret;
}

#ifdef CONFIG_COMPAT
ssize_t compat_rw_copy_check_uvector(int type,
		const struct compat_iovec __user *uvector, unsigned long nr_segs,
		unsigned long fast_segs, struct iovec *fast_pointer,
		struct iovec **ret_pointer)
{
	compat_ssize_t tot_len;
	struct iovec *iov = *ret_pointer = fast_pointer;
	ssize_t ret = 0;
	int seg;

	/*
	 * SuS says "The readv() function *may* fail if the iovcnt argument
	 * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
	 * traditionally returned zero for zero segments, so...
	 */
	if (nr_segs == 0)
		goto out;

	ret = -EINVAL;
	if (nr_segs > UIO_MAXIOV)
		goto out;
	if (nr_segs > fast_segs) {
		ret = -ENOMEM;
		iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
		if (iov == NULL)
			goto out;
	}
	*ret_pointer = iov;

	ret = -EFAULT;
	if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
		goto out;

	/*
	 * Single unix specification:
	 * We should -EINVAL if an element length is not >= 0 and fitting an
	 * ssize_t.
	 *
	 * In Linux, the total length is limited to MAX_RW_COUNT, there is
	 * no overflow possibility.
	 */
	tot_len = 0;
	ret = -EINVAL;
	for (seg = 0; seg < nr_segs; seg++) {
		compat_uptr_t buf;
		compat_ssize_t len;

		if (__get_user(len, &uvector->iov_len) ||
		   __get_user(buf, &uvector->iov_base)) {
			ret = -EFAULT;
			goto out;
		}
		if (len < 0)	/* size_t not fitting in compat_ssize_t .. */
			goto out;
		if (type >= 0 &&
		    !access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
			ret = -EFAULT;
			goto out;
		}
		if (len > MAX_RW_COUNT - tot_len)
			len = MAX_RW_COUNT - tot_len;
		tot_len += len;
		iov->iov_base = compat_ptr(buf);
		iov->iov_len = (compat_size_t) len;
		uvector++;
		iov++;
	}
	ret = tot_len;

out:
	return ret;
}
#endif

static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
		loff_t *pos, int flags)
{
	size_t tot_len;
	ssize_t ret = 0;

	if (!(file->f_mode & FMODE_READ))
		return -EBADF;
	if (!(file->f_mode & FMODE_CAN_READ))
		return -EINVAL;

	tot_len = iov_iter_count(iter);
	if (!tot_len)
		goto out;
	ret = rw_verify_area(READ, file, pos, tot_len);
	if (ret < 0)
		return ret;

	if (file->f_op->read_iter)
		ret = do_iter_readv_writev(file, iter, pos, READ, flags);
	else
		ret = do_loop_readv_writev(file, iter, pos, READ, flags);
out:
	if (ret >= 0)
		fsnotify_access(file);
	return ret;
}

ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
		int flags)
{
	if (!file->f_op->read_iter)
		return -EINVAL;
	return do_iter_read(file, iter, ppos, flags);
}
EXPORT_SYMBOL(vfs_iter_read);

static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
		loff_t *pos, int flags)
{
	size_t tot_len;
	ssize_t ret = 0;

	if (!(file->f_mode & FMODE_WRITE))
		return -EBADF;
	if (!(file->f_mode & FMODE_CAN_WRITE))
		return -EINVAL;

	tot_len = iov_iter_count(iter);
	if (!tot_len)
		return 0;
	ret = rw_verify_area(WRITE, file, pos, tot_len);
	if (ret < 0)
		return ret;

	file_start_write(file);
	if (file->f_op->write_iter)
		ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
	else
		ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
	file_end_write(file);
	if (ret > 0)
		fsnotify_modify(file);
	return ret;
}

ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
		int flags)
{
	if (!file->f_op->write_iter)
		return -EINVAL;
	return do_iter_write(file, iter, ppos, flags);
}
EXPORT_SYMBOL(vfs_iter_write);

ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
		  unsigned long vlen, loff_t *pos, int flags)
{
	struct iovec iovstack[UIO_FASTIOV];
	struct iovec *iov = iovstack;
	struct iov_iter iter;
	ssize_t ret;

	ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
	if (ret >= 0) {
		ret = do_iter_read(file, &iter, pos, flags);
		kfree(iov);
	}

	return ret;
}
EXPORT_SYMBOL(vfs_readv);

ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
		   unsigned long vlen, loff_t *pos, int flags)
{
	struct iovec iovstack[UIO_FASTIOV];
	struct iovec *iov = iovstack;
	struct iov_iter iter;
	ssize_t ret;

	ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
	if (ret >= 0) {
		ret = do_iter_write(file, &iter, pos, flags);
		kfree(iov);
	}
	return ret;
}
EXPORT_SYMBOL(vfs_writev);

static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
			unsigned long vlen, int flags)
{
	struct fd f = fdget_pos(fd);
	ssize_t ret = -EBADF;

	if (f.file) {
		loff_t pos = file_pos_read(f.file);
		ret = vfs_readv(f.file, vec, vlen, &pos, flags);
		if (ret >= 0)
			file_pos_write(f.file, pos);
		fdput_pos(f);
	}

	if (ret > 0)
		add_rchar(current, ret);
	inc_syscr(current);
	return ret;
}

static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
			 unsigned long vlen, int flags)
{
	struct fd f = fdget_pos(fd);
	ssize_t ret = -EBADF;

	if (f.file) {
		loff_t pos = file_pos_read(f.file);
		ret = vfs_writev(f.file, vec, vlen, &pos, flags);
		if (ret >= 0)
			file_pos_write(f.file, pos);
		fdput_pos(f);
	}

	if (ret > 0)
		add_wchar(current, ret);
	inc_syscw(current);
	return ret;
}

static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
{
#define HALF_LONG_BITS (BITS_PER_LONG / 2)
	return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
}

static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
			 unsigned long vlen, loff_t pos, int flags)
{
	struct fd f;
	ssize_t ret = -EBADF;

	if (pos < 0)
		return -EINVAL;

	f = fdget(fd);
	if (f.file) {
		ret = -ESPIPE;
		if (f.file->f_mode & FMODE_PREAD)
			ret = vfs_readv(f.file, vec, vlen, &pos, flags);
		fdput(f);
	}

	if (ret > 0)
		add_rchar(current, ret);
	inc_syscr(current);
	return ret;
}

static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
			  unsigned long vlen, loff_t pos, int flags)
{
	struct fd f;
	ssize_t ret = -EBADF;

	if (pos < 0)
		return -EINVAL;

	f = fdget(fd);
	if (f.file) {
		ret = -ESPIPE;
		if (f.file->f_mode & FMODE_PWRITE)
			ret = vfs_writev(f.file, vec, vlen, &pos, flags);
		fdput(f);
	}

	if (ret > 0)
		add_wchar(current, ret);
	inc_syscw(current);
	return ret;
}

SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
		unsigned long, vlen)
{
	return do_readv(fd, vec, vlen, 0);
}

SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
		unsigned long, vlen)
{
	return do_writev(fd, vec, vlen, 0);
}

SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
{
	loff_t pos = pos_from_hilo(pos_h, pos_l);

	return do_preadv(fd, vec, vlen, pos, 0);
}

SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
		int, flags)
{
	loff_t pos = pos_from_hilo(pos_h, pos_l);

	if (pos == -1)
		return do_readv(fd, vec, vlen, flags);

	return do_preadv(fd, vec, vlen, pos, flags);
}

SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
{
	loff_t pos = pos_from_hilo(pos_h, pos_l);

	return do_pwritev(fd, vec, vlen, pos, 0);
}

SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
		int, flags)
{
	loff_t pos = pos_from_hilo(pos_h, pos_l);

	if (pos == -1)
		return do_writev(fd, vec, vlen, flags);

	return do_pwritev(fd, vec, vlen, pos, flags);
}

#ifdef CONFIG_COMPAT
static size_t compat_readv(struct file *file,
			   const struct compat_iovec __user *vec,
			   unsigned long vlen, loff_t *pos, int flags)
{
	struct iovec iovstack[UIO_FASTIOV];
	struct iovec *iov = iovstack;
	struct iov_iter iter;
	ssize_t ret;

	ret = compat_import_iovec(READ, vec, vlen, UIO_FASTIOV, &iov, &iter);
	if (ret >= 0) {
		ret = do_iter_read(file, &iter, pos, flags);
		kfree(iov);
	}
	if (ret > 0)
		add_rchar(current, ret);
	inc_syscr(current);
	return ret;
}

static size_t do_compat_readv(compat_ulong_t fd,
				 const struct compat_iovec __user *vec,
				 compat_ulong_t vlen, int flags)
{
	struct fd f = fdget_pos(fd);
	ssize_t ret;
	loff_t pos;

	if (!f.file)
		return -EBADF;
	pos = f.file->f_pos;
	ret = compat_readv(f.file, vec, vlen, &pos, flags);
	if (ret >= 0)
		f.file->f_pos = pos;
	fdput_pos(f);
	return ret;

}

COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
		const struct compat_iovec __user *,vec,
		compat_ulong_t, vlen)
{
	return do_compat_readv(fd, vec, vlen, 0);
}

static long do_compat_preadv64(unsigned long fd,
				  const struct compat_iovec __user *vec,
				  unsigned long vlen, loff_t pos, int flags)
{
	struct fd f;
	ssize_t ret;

	if (pos < 0)
		return -EINVAL;
	f = fdget(fd);
	if (!f.file)
		return -EBADF;
	ret = -ESPIPE;
	if (f.file->f_mode & FMODE_PREAD)
		ret = compat_readv(f.file, vec, vlen, &pos, flags);
	fdput(f);
	return ret;
}

#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
		const struct compat_iovec __user *,vec,
		unsigned long, vlen, loff_t, pos)
{
	return do_compat_preadv64(fd, vec, vlen, pos, 0);
}
#endif

COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
		const struct compat_iovec __user *,vec,
		compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
{
	loff_t pos = ((loff_t)pos_high << 32) | pos_low;

	return do_compat_preadv64(fd, vec, vlen, pos, 0);
}

#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
		const struct compat_iovec __user *,vec,
		unsigned long, vlen, loff_t, pos, int, flags)
{
	return do_compat_preadv64(fd, vec, vlen, pos, flags);
}
#endif

COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
		const struct compat_iovec __user *,vec,
		compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
		int, flags)
{
	loff_t pos = ((loff_t)pos_high << 32) | pos_low;

	if (pos == -1)
		return do_compat_readv(fd, vec, vlen, flags);

	return do_compat_preadv64(fd, vec, vlen, pos, flags);
}

static size_t compat_writev(struct file *file,
			    const struct compat_iovec __user *vec,
			    unsigned long vlen, loff_t *pos, int flags)
{
	struct iovec iovstack[UIO_FASTIOV];
	struct iovec *iov = iovstack;
	struct iov_iter iter;
	ssize_t ret;

	ret = compat_import_iovec(WRITE, vec, vlen, UIO_FASTIOV, &iov, &iter);
	if (ret >= 0) {
		ret = do_iter_write(file, &iter, pos, flags);
		kfree(iov);
	}
	if (ret > 0)
		add_wchar(current, ret);
	inc_syscw(current);
	return ret;
}

static size_t do_compat_writev(compat_ulong_t fd,
				  const struct compat_iovec __user* vec,
				  compat_ulong_t vlen, int flags)
{
	struct fd f = fdget_pos(fd);
	ssize_t ret;
	loff_t pos;

	if (!f.file)
		return -EBADF;
	pos = f.file->f_pos;
	ret = compat_writev(f.file, vec, vlen, &pos, flags);
	if (ret >= 0)
		f.file->f_pos = pos;
	fdput_pos(f);
	return ret;
}

COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
		const struct compat_iovec __user *, vec,
		compat_ulong_t, vlen)
{
	return do_compat_writev(fd, vec, vlen, 0);
}

static long do_compat_pwritev64(unsigned long fd,
				   const struct compat_iovec __user *vec,
				   unsigned long vlen, loff_t pos, int flags)
{
	struct fd f;
	ssize_t ret;

	if (pos < 0)
		return -EINVAL;
	f = fdget(fd);
	if (!f.file)
		return -EBADF;
	ret = -ESPIPE;
	if (f.file->f_mode & FMODE_PWRITE)
		ret = compat_writev(f.file, vec, vlen, &pos, flags);
	fdput(f);
	return ret;
}

#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
		const struct compat_iovec __user *,vec,
		unsigned long, vlen, loff_t, pos)
{
	return do_compat_pwritev64(fd, vec, vlen, pos, 0);
}
#endif

COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
		const struct compat_iovec __user *,vec,
		compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
{
	loff_t pos = ((loff_t)pos_high << 32) | pos_low;

	return do_compat_pwritev64(fd, vec, vlen, pos, 0);
}

#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
		const struct compat_iovec __user *,vec,
		unsigned long, vlen, loff_t, pos, int, flags)
{
	return do_compat_pwritev64(fd, vec, vlen, pos, flags);
}
#endif

COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
		const struct compat_iovec __user *,vec,
		compat_ulong_t, vlen, u32, pos_low, u32, pos_high, int, flags)
{
	loff_t pos = ((loff_t)pos_high << 32) | pos_low;

	if (pos == -1)
		return do_compat_writev(fd, vec, vlen, flags);

	return do_compat_pwritev64(fd, vec, vlen, pos, flags);
}

#endif

static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
		  	   size_t count, loff_t max)
{
	struct fd in, out;
	struct inode *in_inode, *out_inode;
	loff_t pos;
	loff_t out_pos;
	ssize_t retval;
	int fl;

	/*
	 * Get input file, and verify that it is ok..
	 */
	retval = -EBADF;
	in = fdget(in_fd);
	if (!in.file)
		goto out;
	if (!(in.file->f_mode & FMODE_READ))
		goto fput_in;
	retval = -ESPIPE;
	if (!ppos) {
		pos = in.file->f_pos;
	} else {
		pos = *ppos;
		if (!(in.file->f_mode & FMODE_PREAD))
			goto fput_in;
	}
	retval = rw_verify_area(READ, in.file, &pos, count);
	if (retval < 0)
		goto fput_in;
	if (count > MAX_RW_COUNT)
		count =  MAX_RW_COUNT;

	/*
	 * Get output file, and verify that it is ok..
	 */
	retval = -EBADF;
	out = fdget(out_fd);
	if (!out.file)
		goto fput_in;
	if (!(out.file->f_mode & FMODE_WRITE))
		goto fput_out;
	retval = -EINVAL;
	in_inode = file_inode(in.file);
	out_inode = file_inode(out.file);
	out_pos = out.file->f_pos;
	retval = rw_verify_area(WRITE, out.file, &out_pos, count);
	if (retval < 0)
		goto fput_out;

	if (!max)
		max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);

	if (unlikely(pos + count > max)) {
		retval = -EOVERFLOW;
		if (pos >= max)
			goto fput_out;
		count = max - pos;
	}

	fl = 0;
#if 0
	/*
	 * We need to debate whether we can enable this or not. The
	 * man page documents EAGAIN return for the output at least,
	 * and the application is arguably buggy if it doesn't expect
	 * EAGAIN on a non-blocking file descriptor.
	 */
	if (in.file->f_flags & O_NONBLOCK)
		fl = SPLICE_F_NONBLOCK;
#endif
	file_start_write(out.file);
	retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
	file_end_write(out.file);

	if (retval > 0) {
		add_rchar(current, retval);
		add_wchar(current, retval);
		fsnotify_access(in.file);
		fsnotify_modify(out.file);
		out.file->f_pos = out_pos;
		if (ppos)
			*ppos = pos;
		else
			in.file->f_pos = pos;
	}

	inc_syscr(current);
	inc_syscw(current);
	if (pos > max)
		retval = -EOVERFLOW;

fput_out:
	fdput(out);
fput_in:
	fdput(in);
out:
	return retval;
}

SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
{
	loff_t pos;
	off_t off;
	ssize_t ret;

	if (offset) {
		if (unlikely(get_user(off, offset)))
			return -EFAULT;
		pos = off;
		ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
		if (unlikely(put_user(pos, offset)))
			return -EFAULT;
		return ret;
	}

	return do_sendfile(out_fd, in_fd, NULL, count, 0);
}

SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
{
	loff_t pos;
	ssize_t ret;

	if (offset) {
		if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
			return -EFAULT;
		ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
		if (unlikely(put_user(pos, offset)))
			return -EFAULT;
		return ret;
	}

	return do_sendfile(out_fd, in_fd, NULL, count, 0);
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
		compat_off_t __user *, offset, compat_size_t, count)
{
	loff_t pos;
	off_t off;
	ssize_t ret;

	if (offset) {
		if (unlikely(get_user(off, offset)))
			return -EFAULT;
		pos = off;
		ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
		if (unlikely(put_user(pos, offset)))
			return -EFAULT;
		return ret;
	}

	return do_sendfile(out_fd, in_fd, NULL, count, 0);
}

COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
		compat_loff_t __user *, offset, compat_size_t, count)
{
	loff_t pos;
	ssize_t ret;

	if (offset) {
		if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
			return -EFAULT;
		ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
		if (unlikely(put_user(pos, offset)))
			return -EFAULT;
		return ret;
	}

	return do_sendfile(out_fd, in_fd, NULL, count, 0);
}
#endif

/*
 * copy_file_range() differs from regular file read and write in that it
 * specifically allows return partial success.  When it does so is up to
 * the copy_file_range method.
 */
ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
			    struct file *file_out, loff_t pos_out,
			    size_t len, unsigned int flags)
{
	struct inode *inode_in = file_inode(file_in);
	struct inode *inode_out = file_inode(file_out);
	ssize_t ret;

	if (flags != 0)
		return -EINVAL;

	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
		return -EISDIR;
	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
		return -EINVAL;

	ret = rw_verify_area(READ, file_in, &pos_in, len);
	if (unlikely(ret))
		return ret;

	ret = rw_verify_area(WRITE, file_out, &pos_out, len);
	if (unlikely(ret))
		return ret;

	if (!(file_in->f_mode & FMODE_READ) ||
	    !(file_out->f_mode & FMODE_WRITE) ||
	    (file_out->f_flags & O_APPEND))
		return -EBADF;

	/* this could be relaxed once a method supports cross-fs copies */
	if (inode_in->i_sb != inode_out->i_sb)
		return -EXDEV;

	if (len == 0)
		return 0;

	file_start_write(file_out);

	/*
	 * Try cloning first, this is supported by more file systems, and
	 * more efficient if both clone and copy are supported (e.g. NFS).
	 */
	if (file_in->f_op->clone_file_range) {
		ret = file_in->f_op->clone_file_range(file_in, pos_in,
				file_out, pos_out, len);
		if (ret == 0) {
			ret = len;
			goto done;
		}
	}

	if (file_out->f_op->copy_file_range) {
		ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
						      pos_out, len, flags);
		if (ret != -EOPNOTSUPP)
			goto done;
	}

	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
			len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);

done:
	if (ret > 0) {
		fsnotify_access(file_in);
		add_rchar(current, ret);
		fsnotify_modify(file_out);
		add_wchar(current, ret);
	}

	inc_syscr(current);
	inc_syscw(current);

	file_end_write(file_out);

	return ret;
}
EXPORT_SYMBOL(vfs_copy_file_range);

SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
		int, fd_out, loff_t __user *, off_out,
		size_t, len, unsigned int, flags)
{
	loff_t pos_in;
	loff_t pos_out;
	struct fd f_in;
	struct fd f_out;
	ssize_t ret = -EBADF;

	f_in = fdget(fd_in);
	if (!f_in.file)
		goto out2;

	f_out = fdget(fd_out);
	if (!f_out.file)
		goto out1;

	ret = -EFAULT;
	if (off_in) {
		if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
			goto out;
	} else {
		pos_in = f_in.file->f_pos;
	}

	if (off_out) {
		if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
			goto out;
	} else {
		pos_out = f_out.file->f_pos;
	}

	ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
				  flags);
	if (ret > 0) {
		pos_in += ret;
		pos_out += ret;

		if (off_in) {
			if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
				ret = -EFAULT;
		} else {
			f_in.file->f_pos = pos_in;
		}

		if (off_out) {
			if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
				ret = -EFAULT;
		} else {
			f_out.file->f_pos = pos_out;
		}
	}

out:
	fdput(f_out);
out1:
	fdput(f_in);
out2:
	return ret;
}

static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
{
	struct inode *inode = file_inode(file);

	if (unlikely(pos < 0))
		return -EINVAL;

	 if (unlikely((loff_t) (pos + len) < 0))
		return -EINVAL;

	if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
		loff_t end = len ? pos + len - 1 : OFFSET_MAX;
		int retval;

		retval = locks_mandatory_area(inode, file, pos, end,
				write ? F_WRLCK : F_RDLCK);
		if (retval < 0)
			return retval;
	}

	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
}

/*
 * Check that the two inodes are eligible for cloning, the ranges make
 * sense, and then flush all dirty data.  Caller must ensure that the
 * inodes have been locked against any other modifications.
 *
 * Returns: 0 for "nothing to clone", 1 for "something to clone", or
 * the usual negative error code.
 */
int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in,
			       struct inode *inode_out, loff_t pos_out,
			       u64 *len, bool is_dedupe)
{
	loff_t bs = inode_out->i_sb->s_blocksize;
	loff_t blen;
	loff_t isize;
	bool same_inode = (inode_in == inode_out);
	int ret;

	/* Don't touch certain kinds of inodes */
	if (IS_IMMUTABLE(inode_out))
		return -EPERM;

	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
		return -ETXTBSY;

	/* Don't reflink dirs, pipes, sockets... */
	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
		return -EISDIR;
	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
		return -EINVAL;

	/* Are we going all the way to the end? */
	isize = i_size_read(inode_in);
	if (isize == 0)
		return 0;

	/* Zero length dedupe exits immediately; reflink goes to EOF. */
	if (*len == 0) {
		if (is_dedupe || pos_in == isize)
			return 0;
		if (pos_in > isize)
			return -EINVAL;
		*len = isize - pos_in;
	}

	/* Ensure offsets don't wrap and the input is inside i_size */
	if (pos_in + *len < pos_in || pos_out + *len < pos_out ||
	    pos_in + *len > isize)
		return -EINVAL;

	/* Don't allow dedupe past EOF in the dest file */
	if (is_dedupe) {
		loff_t	disize;

		disize = i_size_read(inode_out);
		if (pos_out >= disize || pos_out + *len > disize)
			return -EINVAL;
	}

	/* If we're linking to EOF, continue to the block boundary. */
	if (pos_in + *len == isize)
		blen = ALIGN(isize, bs) - pos_in;
	else
		blen = *len;

	/* Only reflink if we're aligned to block boundaries */
	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) ||
	    !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs))
		return -EINVAL;

	/* Don't allow overlapped reflink within the same file */
	if (same_inode) {
		if (pos_out + blen > pos_in && pos_out < pos_in + blen)
			return -EINVAL;
	}

	/* Wait for the completion of any pending IOs on both files */
	inode_dio_wait(inode_in);
	if (!same_inode)
		inode_dio_wait(inode_out);

	ret = filemap_write_and_wait_range(inode_in->i_mapping,
			pos_in, pos_in + *len - 1);
	if (ret)
		return ret;

	ret = filemap_write_and_wait_range(inode_out->i_mapping,
			pos_out, pos_out + *len - 1);
	if (ret)
		return ret;

	/*
	 * Check that the extents are the same.
	 */
	if (is_dedupe) {
		bool		is_same = false;

		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
				inode_out, pos_out, *len, &is_same);
		if (ret)
			return ret;
		if (!is_same)
			return -EBADE;
	}

	return 1;
}
EXPORT_SYMBOL(vfs_clone_file_prep_inodes);

int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
		struct file *file_out, loff_t pos_out, u64 len)
{
	struct inode *inode_in = file_inode(file_in);
	struct inode *inode_out = file_inode(file_out);
	int ret;

	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
		return -EISDIR;
	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
		return -EINVAL;

	/*
	 * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
	 * the same mount. Practically, they only need to be on the same file
	 * system.
	 */
	if (inode_in->i_sb != inode_out->i_sb)
		return -EXDEV;

	if (!(file_in->f_mode & FMODE_READ) ||
	    !(file_out->f_mode & FMODE_WRITE) ||
	    (file_out->f_flags & O_APPEND))
		return -EBADF;

	if (!file_in->f_op->clone_file_range)
		return -EOPNOTSUPP;

	ret = clone_verify_area(file_in, pos_in, len, false);
	if (ret)
		return ret;

	ret = clone_verify_area(file_out, pos_out, len, true);
	if (ret)
		return ret;

	if (pos_in + len > i_size_read(inode_in))
		return -EINVAL;

	ret = file_in->f_op->clone_file_range(file_in, pos_in,
			file_out, pos_out, len);
	if (!ret) {
		fsnotify_access(file_in);
		fsnotify_modify(file_out);
	}

	return ret;
}
EXPORT_SYMBOL(vfs_clone_file_range);

/*
 * Read a page's worth of file data into the page cache.  Return the page
 * locked.
 */
static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
{
	struct address_space *mapping;
	struct page *page;
	pgoff_t n;

	n = offset >> PAGE_SHIFT;
	mapping = inode->i_mapping;
	page = read_mapping_page(mapping, n, NULL);
	if (IS_ERR(page))
		return page;
	if (!PageUptodate(page)) {
		put_page(page);
		return ERR_PTR(-EIO);
	}
	lock_page(page);
	return page;
}

/*
 * Compare extents of two files to see if they are the same.
 * Caller must have locked both inodes to prevent write races.
 */
int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
				  struct inode *dest, loff_t destoff,
				  loff_t len, bool *is_same)
{
	loff_t src_poff;
	loff_t dest_poff;
	void *src_addr;
	void *dest_addr;
	struct page *src_page;
	struct page *dest_page;
	loff_t cmp_len;
	bool same;
	int error;

	error = -EINVAL;
	same = true;
	while (len) {
		src_poff = srcoff & (PAGE_SIZE - 1);
		dest_poff = destoff & (PAGE_SIZE - 1);
		cmp_len = min(PAGE_SIZE - src_poff,
			      PAGE_SIZE - dest_poff);
		cmp_len = min(cmp_len, len);
		if (cmp_len <= 0)
			goto out_error;

		src_page = vfs_dedupe_get_page(src, srcoff);
		if (IS_ERR(src_page)) {
			error = PTR_ERR(src_page);
			goto out_error;
		}
		dest_page = vfs_dedupe_get_page(dest, destoff);
		if (IS_ERR(dest_page)) {
			error = PTR_ERR(dest_page);
			unlock_page(src_page);
			put_page(src_page);
			goto out_error;
		}
		src_addr = kmap_atomic(src_page);
		dest_addr = kmap_atomic(dest_page);

		flush_dcache_page(src_page);
		flush_dcache_page(dest_page);

		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
			same = false;

		kunmap_atomic(dest_addr);
		kunmap_atomic(src_addr);
		unlock_page(dest_page);
		unlock_page(src_page);
		put_page(dest_page);
		put_page(src_page);

		if (!same)
			break;

		srcoff += cmp_len;
		destoff += cmp_len;
		len -= cmp_len;
	}

	*is_same = same;
	return 0;

out_error:
	return error;
}
EXPORT_SYMBOL(vfs_dedupe_file_range_compare);

int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
{
	struct file_dedupe_range_info *info;
	struct inode *src = file_inode(file);
	u64 off;
	u64 len;
	int i;
	int ret;
	bool is_admin = capable(CAP_SYS_ADMIN);
	u16 count = same->dest_count;
	struct file *dst_file;
	loff_t dst_off;
	ssize_t deduped;

	if (!(file->f_mode & FMODE_READ))
		return -EINVAL;

	if (same->reserved1 || same->reserved2)
		return -EINVAL;

	off = same->src_offset;
	len = same->src_length;

	ret = -EISDIR;
	if (S_ISDIR(src->i_mode))
		goto out;

	ret = -EINVAL;
	if (!S_ISREG(src->i_mode))
		goto out;

	ret = clone_verify_area(file, off, len, false);
	if (ret < 0)
		goto out;
	ret = 0;

	if (off + len > i_size_read(src))
		return -EINVAL;

	/* pre-format output fields to sane values */
	for (i = 0; i < count; i++) {
		same->info[i].bytes_deduped = 0ULL;
		same->info[i].status = FILE_DEDUPE_RANGE_SAME;
	}

	for (i = 0, info = same->info; i < count; i++, info++) {
		struct inode *dst;
		struct fd dst_fd = fdget(info->dest_fd);

		dst_file = dst_fd.file;
		if (!dst_file) {
			info->status = -EBADF;
			goto next_loop;
		}
		dst = file_inode(dst_file);

		ret = mnt_want_write_file(dst_file);
		if (ret) {
			info->status = ret;
			goto next_loop;
		}

		dst_off = info->dest_offset;
		ret = clone_verify_area(dst_file, dst_off, len, true);
		if (ret < 0) {
			info->status = ret;
			goto next_file;
		}
		ret = 0;

		if (info->reserved) {
			info->status = -EINVAL;
		} else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
			info->status = -EINVAL;
		} else if (file->f_path.mnt != dst_file->f_path.mnt) {
			info->status = -EXDEV;
		} else if (S_ISDIR(dst->i_mode)) {
			info->status = -EISDIR;
		} else if (dst_file->f_op->dedupe_file_range == NULL) {
			info->status = -EINVAL;
		} else {
			deduped = dst_file->f_op->dedupe_file_range(file, off,
							len, dst_file,
							info->dest_offset);
			if (deduped == -EBADE)
				info->status = FILE_DEDUPE_RANGE_DIFFERS;
			else if (deduped < 0)
				info->status = deduped;
			else
				info->bytes_deduped += deduped;
		}

next_file:
		mnt_drop_write_file(dst_file);
next_loop:
		fdput(dst_fd);

		if (fatal_signal_pending(current))
			goto out;
	}

out:
	return ret;
}
EXPORT_SYMBOL(vfs_dedupe_file_range);