summaryrefslogtreecommitdiff
path: root/fs/btrfs/file-item.c
blob: 45cae356e89ba086e62743eba2625deabc1248bc (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 */

#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/sched/mm.h>
#include <crypto/hash.h>
#include "messages.h"
#include "misc.h"
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "bio.h"
#include "print-tree.h"
#include "compression.h"
#include "fs.h"
#include "accessors.h"
#include "file-item.h"
#include "super.h"

#define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
				   sizeof(struct btrfs_item) * 2) / \
				  size) - 1))

#define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
				       PAGE_SIZE))

/*
 * Set inode's size according to filesystem options.
 *
 * @inode:      inode we want to update the disk_i_size for
 * @new_i_size: i_size we want to set to, 0 if we use i_size
 *
 * With NO_HOLES set this simply sets the disk_is_size to whatever i_size_read()
 * returns as it is perfectly fine with a file that has holes without hole file
 * extent items.
 *
 * However without NO_HOLES we need to only return the area that is contiguous
 * from the 0 offset of the file.  Otherwise we could end up adjust i_size up
 * to an extent that has a gap in between.
 *
 * Finally new_i_size should only be set in the case of truncate where we're not
 * ready to use i_size_read() as the limiter yet.
 */
void btrfs_inode_safe_disk_i_size_write(struct btrfs_inode *inode, u64 new_i_size)
{
	struct btrfs_fs_info *fs_info = inode->root->fs_info;
	u64 start, end, i_size;
	int ret;

	spin_lock(&inode->lock);
	i_size = new_i_size ?: i_size_read(&inode->vfs_inode);
	if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
		inode->disk_i_size = i_size;
		goto out_unlock;
	}

	ret = find_contiguous_extent_bit(&inode->file_extent_tree, 0, &start,
					 &end, EXTENT_DIRTY);
	if (!ret && start == 0)
		i_size = min(i_size, end + 1);
	else
		i_size = 0;
	inode->disk_i_size = i_size;
out_unlock:
	spin_unlock(&inode->lock);
}

/*
 * Mark range within a file as having a new extent inserted.
 *
 * @inode: inode being modified
 * @start: start file offset of the file extent we've inserted
 * @len:   logical length of the file extent item
 *
 * Call when we are inserting a new file extent where there was none before.
 * Does not need to call this in the case where we're replacing an existing file
 * extent, however if not sure it's fine to call this multiple times.
 *
 * The start and len must match the file extent item, so thus must be sectorsize
 * aligned.
 */
int btrfs_inode_set_file_extent_range(struct btrfs_inode *inode, u64 start,
				      u64 len)
{
	if (len == 0)
		return 0;

	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize));

	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
		return 0;
	return set_extent_bit(&inode->file_extent_tree, start, start + len - 1,
			      EXTENT_DIRTY, NULL);
}

/*
 * Mark an inode range as not having a backing extent.
 *
 * @inode: inode being modified
 * @start: start file offset of the file extent we've inserted
 * @len:   logical length of the file extent item
 *
 * Called when we drop a file extent, for example when we truncate.  Doesn't
 * need to be called for cases where we're replacing a file extent, like when
 * we've COWed a file extent.
 *
 * The start and len must match the file extent item, so thus must be sectorsize
 * aligned.
 */
int btrfs_inode_clear_file_extent_range(struct btrfs_inode *inode, u64 start,
					u64 len)
{
	if (len == 0)
		return 0;

	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize) ||
	       len == (u64)-1);

	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
		return 0;
	return clear_extent_bit(&inode->file_extent_tree, start,
				start + len - 1, EXTENT_DIRTY, NULL);
}

static size_t bytes_to_csum_size(const struct btrfs_fs_info *fs_info, u32 bytes)
{
	ASSERT(IS_ALIGNED(bytes, fs_info->sectorsize));

	return (bytes >> fs_info->sectorsize_bits) * fs_info->csum_size;
}

static size_t csum_size_to_bytes(const struct btrfs_fs_info *fs_info, u32 csum_size)
{
	ASSERT(IS_ALIGNED(csum_size, fs_info->csum_size));

	return (csum_size / fs_info->csum_size) << fs_info->sectorsize_bits;
}

static inline u32 max_ordered_sum_bytes(const struct btrfs_fs_info *fs_info)
{
	u32 max_csum_size = round_down(PAGE_SIZE - sizeof(struct btrfs_ordered_sum),
				       fs_info->csum_size);

	return csum_size_to_bytes(fs_info, max_csum_size);
}

/*
 * Calculate the total size needed to allocate for an ordered sum structure
 * spanning @bytes in the file.
 */
static int btrfs_ordered_sum_size(struct btrfs_fs_info *fs_info, unsigned long bytes)
{
	return sizeof(struct btrfs_ordered_sum) + bytes_to_csum_size(fs_info, bytes);
}

int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root,
			     u64 objectid, u64 pos, u64 num_bytes)
{
	int ret = 0;
	struct btrfs_file_extent_item *item;
	struct btrfs_key file_key;
	struct btrfs_path *path;
	struct extent_buffer *leaf;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
	file_key.objectid = objectid;
	file_key.offset = pos;
	file_key.type = BTRFS_EXTENT_DATA_KEY;

	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
				      sizeof(*item));
	if (ret < 0)
		goto out;
	BUG_ON(ret); /* Can't happen */
	leaf = path->nodes[0];
	item = btrfs_item_ptr(leaf, path->slots[0],
			      struct btrfs_file_extent_item);
	btrfs_set_file_extent_disk_bytenr(leaf, item, 0);
	btrfs_set_file_extent_disk_num_bytes(leaf, item, 0);
	btrfs_set_file_extent_offset(leaf, item, 0);
	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
	btrfs_set_file_extent_ram_bytes(leaf, item, num_bytes);
	btrfs_set_file_extent_generation(leaf, item, trans->transid);
	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
	btrfs_set_file_extent_compression(leaf, item, 0);
	btrfs_set_file_extent_encryption(leaf, item, 0);
	btrfs_set_file_extent_other_encoding(leaf, item, 0);

	btrfs_mark_buffer_dirty(trans, leaf);
out:
	btrfs_free_path(path);
	return ret;
}

static struct btrfs_csum_item *
btrfs_lookup_csum(struct btrfs_trans_handle *trans,
		  struct btrfs_root *root,
		  struct btrfs_path *path,
		  u64 bytenr, int cow)
{
	struct btrfs_fs_info *fs_info = root->fs_info;
	int ret;
	struct btrfs_key file_key;
	struct btrfs_key found_key;
	struct btrfs_csum_item *item;
	struct extent_buffer *leaf;
	u64 csum_offset = 0;
	const u32 csum_size = fs_info->csum_size;
	int csums_in_item;

	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
	file_key.offset = bytenr;
	file_key.type = BTRFS_EXTENT_CSUM_KEY;
	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
	if (ret < 0)
		goto fail;
	leaf = path->nodes[0];
	if (ret > 0) {
		ret = 1;
		if (path->slots[0] == 0)
			goto fail;
		path->slots[0]--;
		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
		if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
			goto fail;

		csum_offset = (bytenr - found_key.offset) >>
				fs_info->sectorsize_bits;
		csums_in_item = btrfs_item_size(leaf, path->slots[0]);
		csums_in_item /= csum_size;

		if (csum_offset == csums_in_item) {
			ret = -EFBIG;
			goto fail;
		} else if (csum_offset > csums_in_item) {
			goto fail;
		}
	}
	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
	item = (struct btrfs_csum_item *)((unsigned char *)item +
					  csum_offset * csum_size);
	return item;
fail:
	if (ret > 0)
		ret = -ENOENT;
	return ERR_PTR(ret);
}

int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root,
			     struct btrfs_path *path, u64 objectid,
			     u64 offset, int mod)
{
	struct btrfs_key file_key;
	int ins_len = mod < 0 ? -1 : 0;
	int cow = mod != 0;

	file_key.objectid = objectid;
	file_key.offset = offset;
	file_key.type = BTRFS_EXTENT_DATA_KEY;

	return btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
}

/*
 * Find checksums for logical bytenr range [disk_bytenr, disk_bytenr + len) and
 * store the result to @dst.
 *
 * Return >0 for the number of sectors we found.
 * Return 0 for the range [disk_bytenr, disk_bytenr + sectorsize) has no csum
 * for it. Caller may want to try next sector until one range is hit.
 * Return <0 for fatal error.
 */
static int search_csum_tree(struct btrfs_fs_info *fs_info,
			    struct btrfs_path *path, u64 disk_bytenr,
			    u64 len, u8 *dst)
{
	struct btrfs_root *csum_root;
	struct btrfs_csum_item *item = NULL;
	struct btrfs_key key;
	const u32 sectorsize = fs_info->sectorsize;
	const u32 csum_size = fs_info->csum_size;
	u32 itemsize;
	int ret;
	u64 csum_start;
	u64 csum_len;

	ASSERT(IS_ALIGNED(disk_bytenr, sectorsize) &&
	       IS_ALIGNED(len, sectorsize));

	/* Check if the current csum item covers disk_bytenr */
	if (path->nodes[0]) {
		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
				      struct btrfs_csum_item);
		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
		itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);

		csum_start = key.offset;
		csum_len = (itemsize / csum_size) * sectorsize;

		if (in_range(disk_bytenr, csum_start, csum_len))
			goto found;
	}

	/* Current item doesn't contain the desired range, search again */
	btrfs_release_path(path);
	csum_root = btrfs_csum_root(fs_info, disk_bytenr);
	item = btrfs_lookup_csum(NULL, csum_root, path, disk_bytenr, 0);
	if (IS_ERR(item)) {
		ret = PTR_ERR(item);
		goto out;
	}
	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
	itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);

	csum_start = key.offset;
	csum_len = (itemsize / csum_size) * sectorsize;
	ASSERT(in_range(disk_bytenr, csum_start, csum_len));

found:
	ret = (min(csum_start + csum_len, disk_bytenr + len) -
		   disk_bytenr) >> fs_info->sectorsize_bits;
	read_extent_buffer(path->nodes[0], dst, (unsigned long)item,
			ret * csum_size);
out:
	if (ret == -ENOENT || ret == -EFBIG)
		ret = 0;
	return ret;
}

/*
 * Lookup the checksum for the read bio in csum tree.
 *
 * Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
 */
blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio)
{
	struct btrfs_inode *inode = bbio->inode;
	struct btrfs_fs_info *fs_info = inode->root->fs_info;
	struct bio *bio = &bbio->bio;
	struct btrfs_path *path;
	const u32 sectorsize = fs_info->sectorsize;
	const u32 csum_size = fs_info->csum_size;
	u32 orig_len = bio->bi_iter.bi_size;
	u64 orig_disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
	const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
	blk_status_t ret = BLK_STS_OK;
	u32 bio_offset = 0;

	if ((inode->flags & BTRFS_INODE_NODATASUM) ||
	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
		return BLK_STS_OK;

	/*
	 * This function is only called for read bio.
	 *
	 * This means two things:
	 * - All our csums should only be in csum tree
	 *   No ordered extents csums, as ordered extents are only for write
	 *   path.
	 * - No need to bother any other info from bvec
	 *   Since we're looking up csums, the only important info is the
	 *   disk_bytenr and the length, which can be extracted from bi_iter
	 *   directly.
	 */
	ASSERT(bio_op(bio) == REQ_OP_READ);
	path = btrfs_alloc_path();
	if (!path)
		return BLK_STS_RESOURCE;

	if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
		bbio->csum = kmalloc_array(nblocks, csum_size, GFP_NOFS);
		if (!bbio->csum) {
			btrfs_free_path(path);
			return BLK_STS_RESOURCE;
		}
	} else {
		bbio->csum = bbio->csum_inline;
	}

	/*
	 * If requested number of sectors is larger than one leaf can contain,
	 * kick the readahead for csum tree.
	 */
	if (nblocks > fs_info->csums_per_leaf)
		path->reada = READA_FORWARD;

	/*
	 * the free space stuff is only read when it hasn't been
	 * updated in the current transaction.  So, we can safely
	 * read from the commit root and sidestep a nasty deadlock
	 * between reading the free space cache and updating the csum tree.
	 */
	if (btrfs_is_free_space_inode(inode)) {
		path->search_commit_root = 1;
		path->skip_locking = 1;
	}

	while (bio_offset < orig_len) {
		int count;
		u64 cur_disk_bytenr = orig_disk_bytenr + bio_offset;
		u8 *csum_dst = bbio->csum +
			(bio_offset >> fs_info->sectorsize_bits) * csum_size;

		count = search_csum_tree(fs_info, path, cur_disk_bytenr,
					 orig_len - bio_offset, csum_dst);
		if (count < 0) {
			ret = errno_to_blk_status(count);
			if (bbio->csum != bbio->csum_inline)
				kfree(bbio->csum);
			bbio->csum = NULL;
			break;
		}

		/*
		 * We didn't find a csum for this range.  We need to make sure
		 * we complain loudly about this, because we are not NODATASUM.
		 *
		 * However for the DATA_RELOC inode we could potentially be
		 * relocating data extents for a NODATASUM inode, so the inode
		 * itself won't be marked with NODATASUM, but the extent we're
		 * copying is in fact NODATASUM.  If we don't find a csum we
		 * assume this is the case.
		 */
		if (count == 0) {
			memset(csum_dst, 0, csum_size);
			count = 1;

			if (inode->root->root_key.objectid ==
			    BTRFS_DATA_RELOC_TREE_OBJECTID) {
				u64 file_offset = bbio->file_offset + bio_offset;

				set_extent_bit(&inode->io_tree, file_offset,
					       file_offset + sectorsize - 1,
					       EXTENT_NODATASUM, NULL);
			} else {
				btrfs_warn_rl(fs_info,
			"csum hole found for disk bytenr range [%llu, %llu)",
				cur_disk_bytenr, cur_disk_bytenr + sectorsize);
			}
		}
		bio_offset += count * sectorsize;
	}

	btrfs_free_path(path);
	return ret;
}

int btrfs_lookup_csums_list(struct btrfs_root *root, u64 start, u64 end,
			    struct list_head *list, int search_commit,
			    bool nowait)
{
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct btrfs_key key;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct btrfs_ordered_sum *sums;
	struct btrfs_csum_item *item;
	LIST_HEAD(tmplist);
	int ret;

	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
	       IS_ALIGNED(end + 1, fs_info->sectorsize));

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	path->nowait = nowait;
	if (search_commit) {
		path->skip_locking = 1;
		path->reada = READA_FORWARD;
		path->search_commit_root = 1;
	}

	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
	key.offset = start;
	key.type = BTRFS_EXTENT_CSUM_KEY;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto fail;
	if (ret > 0 && path->slots[0] > 0) {
		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);

		/*
		 * There are two cases we can hit here for the previous csum
		 * item:
		 *
		 *		|<- search range ->|
		 *	|<- csum item ->|
		 *
		 * Or
		 *				|<- search range ->|
		 *	|<- csum item ->|
		 *
		 * Check if the previous csum item covers the leading part of
		 * the search range.  If so we have to start from previous csum
		 * item.
		 */
		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
		    key.type == BTRFS_EXTENT_CSUM_KEY) {
			if (bytes_to_csum_size(fs_info, start - key.offset) <
			    btrfs_item_size(leaf, path->slots[0] - 1))
				path->slots[0]--;
		}
	}

	while (start <= end) {
		u64 csum_end;

		leaf = path->nodes[0];
		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
			ret = btrfs_next_leaf(root, path);
			if (ret < 0)
				goto fail;
			if (ret > 0)
				break;
			leaf = path->nodes[0];
		}

		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
		    key.type != BTRFS_EXTENT_CSUM_KEY ||
		    key.offset > end)
			break;

		if (key.offset > start)
			start = key.offset;

		csum_end = key.offset + csum_size_to_bytes(fs_info,
					btrfs_item_size(leaf, path->slots[0]));
		if (csum_end <= start) {
			path->slots[0]++;
			continue;
		}

		csum_end = min(csum_end, end + 1);
		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
				      struct btrfs_csum_item);
		while (start < csum_end) {
			unsigned long offset;
			size_t size;

			size = min_t(size_t, csum_end - start,
				     max_ordered_sum_bytes(fs_info));
			sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
				       GFP_NOFS);
			if (!sums) {
				ret = -ENOMEM;
				goto fail;
			}

			sums->logical = start;
			sums->len = size;

			offset = bytes_to_csum_size(fs_info, start - key.offset);

			read_extent_buffer(path->nodes[0],
					   sums->sums,
					   ((unsigned long)item) + offset,
					   bytes_to_csum_size(fs_info, size));

			start += size;
			list_add_tail(&sums->list, &tmplist);
		}
		path->slots[0]++;
	}
	ret = 0;
fail:
	while (ret < 0 && !list_empty(&tmplist)) {
		sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
		list_del(&sums->list);
		kfree(sums);
	}
	list_splice_tail(&tmplist, list);

	btrfs_free_path(path);
	return ret;
}

/*
 * Do the same work as btrfs_lookup_csums_list(), the difference is in how
 * we return the result.
 *
 * This version will set the corresponding bits in @csum_bitmap to represent
 * that there is a csum found.
 * Each bit represents a sector. Thus caller should ensure @csum_buf passed
 * in is large enough to contain all csums.
 */
int btrfs_lookup_csums_bitmap(struct btrfs_root *root, struct btrfs_path *path,
			      u64 start, u64 end, u8 *csum_buf,
			      unsigned long *csum_bitmap)
{
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct btrfs_key key;
	struct extent_buffer *leaf;
	struct btrfs_csum_item *item;
	const u64 orig_start = start;
	bool free_path = false;
	int ret;

	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
	       IS_ALIGNED(end + 1, fs_info->sectorsize));

	if (!path) {
		path = btrfs_alloc_path();
		if (!path)
			return -ENOMEM;
		free_path = true;
	}

	/* Check if we can reuse the previous path. */
	if (path->nodes[0]) {
		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);

		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
		    key.type == BTRFS_EXTENT_CSUM_KEY &&
		    key.offset <= start)
			goto search_forward;
		btrfs_release_path(path);
	}

	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
	key.type = BTRFS_EXTENT_CSUM_KEY;
	key.offset = start;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto fail;
	if (ret > 0 && path->slots[0] > 0) {
		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);

		/*
		 * There are two cases we can hit here for the previous csum
		 * item:
		 *
		 *		|<- search range ->|
		 *	|<- csum item ->|
		 *
		 * Or
		 *				|<- search range ->|
		 *	|<- csum item ->|
		 *
		 * Check if the previous csum item covers the leading part of
		 * the search range.  If so we have to start from previous csum
		 * item.
		 */
		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
		    key.type == BTRFS_EXTENT_CSUM_KEY) {
			if (bytes_to_csum_size(fs_info, start - key.offset) <
			    btrfs_item_size(leaf, path->slots[0] - 1))
				path->slots[0]--;
		}
	}

search_forward:
	while (start <= end) {
		u64 csum_end;

		leaf = path->nodes[0];
		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
			ret = btrfs_next_leaf(root, path);
			if (ret < 0)
				goto fail;
			if (ret > 0)
				break;
			leaf = path->nodes[0];
		}

		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
		    key.type != BTRFS_EXTENT_CSUM_KEY ||
		    key.offset > end)
			break;

		if (key.offset > start)
			start = key.offset;

		csum_end = key.offset + csum_size_to_bytes(fs_info,
					btrfs_item_size(leaf, path->slots[0]));
		if (csum_end <= start) {
			path->slots[0]++;
			continue;
		}

		csum_end = min(csum_end, end + 1);
		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
				      struct btrfs_csum_item);
		while (start < csum_end) {
			unsigned long offset;
			size_t size;
			u8 *csum_dest = csum_buf + bytes_to_csum_size(fs_info,
						start - orig_start);

			size = min_t(size_t, csum_end - start, end + 1 - start);

			offset = bytes_to_csum_size(fs_info, start - key.offset);

			read_extent_buffer(path->nodes[0], csum_dest,
					   ((unsigned long)item) + offset,
					   bytes_to_csum_size(fs_info, size));

			bitmap_set(csum_bitmap,
				(start - orig_start) >> fs_info->sectorsize_bits,
				size >> fs_info->sectorsize_bits);

			start += size;
		}
		path->slots[0]++;
	}
	ret = 0;
fail:
	if (free_path)
		btrfs_free_path(path);
	return ret;
}

/*
 * Calculate checksums of the data contained inside a bio.
 */
blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio)
{
	struct btrfs_ordered_extent *ordered = bbio->ordered;
	struct btrfs_inode *inode = bbio->inode;
	struct btrfs_fs_info *fs_info = inode->root->fs_info;
	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
	struct bio *bio = &bbio->bio;
	struct btrfs_ordered_sum *sums;
	char *data;
	struct bvec_iter iter;
	struct bio_vec bvec;
	int index;
	unsigned int blockcount;
	int i;
	unsigned nofs_flag;

	nofs_flag = memalloc_nofs_save();
	sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
		       GFP_KERNEL);
	memalloc_nofs_restore(nofs_flag);

	if (!sums)
		return BLK_STS_RESOURCE;

	sums->len = bio->bi_iter.bi_size;
	INIT_LIST_HEAD(&sums->list);

	sums->logical = bio->bi_iter.bi_sector << SECTOR_SHIFT;
	index = 0;

	shash->tfm = fs_info->csum_shash;

	bio_for_each_segment(bvec, bio, iter) {
		blockcount = BTRFS_BYTES_TO_BLKS(fs_info,
						 bvec.bv_len + fs_info->sectorsize
						 - 1);

		for (i = 0; i < blockcount; i++) {
			data = bvec_kmap_local(&bvec);
			crypto_shash_digest(shash,
					    data + (i * fs_info->sectorsize),
					    fs_info->sectorsize,
					    sums->sums + index);
			kunmap_local(data);
			index += fs_info->csum_size;
		}

	}

	bbio->sums = sums;
	btrfs_add_ordered_sum(ordered, sums);
	return 0;
}

/*
 * Nodatasum I/O on zoned file systems still requires an btrfs_ordered_sum to
 * record the updated logical address on Zone Append completion.
 * Allocate just the structure with an empty sums array here for that case.
 */
blk_status_t btrfs_alloc_dummy_sum(struct btrfs_bio *bbio)
{
	bbio->sums = kmalloc(sizeof(*bbio->sums), GFP_NOFS);
	if (!bbio->sums)
		return BLK_STS_RESOURCE;
	bbio->sums->len = bbio->bio.bi_iter.bi_size;
	bbio->sums->logical = bbio->bio.bi_iter.bi_sector << SECTOR_SHIFT;
	btrfs_add_ordered_sum(bbio->ordered, bbio->sums);
	return 0;
}

/*
 * Remove one checksum overlapping a range.
 *
 * This expects the key to describe the csum pointed to by the path, and it
 * expects the csum to overlap the range [bytenr, len]
 *
 * The csum should not be entirely contained in the range and the range should
 * not be entirely contained in the csum.
 *
 * This calls btrfs_truncate_item with the correct args based on the overlap,
 * and fixes up the key as required.
 */
static noinline void truncate_one_csum(struct btrfs_trans_handle *trans,
				       struct btrfs_path *path,
				       struct btrfs_key *key,
				       u64 bytenr, u64 len)
{
	struct btrfs_fs_info *fs_info = trans->fs_info;
	struct extent_buffer *leaf;
	const u32 csum_size = fs_info->csum_size;
	u64 csum_end;
	u64 end_byte = bytenr + len;
	u32 blocksize_bits = fs_info->sectorsize_bits;

	leaf = path->nodes[0];
	csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
	csum_end <<= blocksize_bits;
	csum_end += key->offset;

	if (key->offset < bytenr && csum_end <= end_byte) {
		/*
		 *         [ bytenr - len ]
		 *         [   ]
		 *   [csum     ]
		 *   A simple truncate off the end of the item
		 */
		u32 new_size = (bytenr - key->offset) >> blocksize_bits;
		new_size *= csum_size;
		btrfs_truncate_item(trans, path, new_size, 1);
	} else if (key->offset >= bytenr && csum_end > end_byte &&
		   end_byte > key->offset) {
		/*
		 *         [ bytenr - len ]
		 *                 [ ]
		 *                 [csum     ]
		 * we need to truncate from the beginning of the csum
		 */
		u32 new_size = (csum_end - end_byte) >> blocksize_bits;
		new_size *= csum_size;

		btrfs_truncate_item(trans, path, new_size, 0);

		key->offset = end_byte;
		btrfs_set_item_key_safe(trans, path, key);
	} else {
		BUG();
	}
}

/*
 * Delete the csum items from the csum tree for a given range of bytes.
 */
int btrfs_del_csums(struct btrfs_trans_handle *trans,
		    struct btrfs_root *root, u64 bytenr, u64 len)
{
	struct btrfs_fs_info *fs_info = trans->fs_info;
	struct btrfs_path *path;
	struct btrfs_key key;
	u64 end_byte = bytenr + len;
	u64 csum_end;
	struct extent_buffer *leaf;
	int ret = 0;
	const u32 csum_size = fs_info->csum_size;
	u32 blocksize_bits = fs_info->sectorsize_bits;

	ASSERT(root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID ||
	       root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	while (1) {
		key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
		key.offset = end_byte - 1;
		key.type = BTRFS_EXTENT_CSUM_KEY;

		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
		if (ret > 0) {
			ret = 0;
			if (path->slots[0] == 0)
				break;
			path->slots[0]--;
		} else if (ret < 0) {
			break;
		}

		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);

		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
		    key.type != BTRFS_EXTENT_CSUM_KEY) {
			break;
		}

		if (key.offset >= end_byte)
			break;

		csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
		csum_end <<= blocksize_bits;
		csum_end += key.offset;

		/* this csum ends before we start, we're done */
		if (csum_end <= bytenr)
			break;

		/* delete the entire item, it is inside our range */
		if (key.offset >= bytenr && csum_end <= end_byte) {
			int del_nr = 1;

			/*
			 * Check how many csum items preceding this one in this
			 * leaf correspond to our range and then delete them all
			 * at once.
			 */
			if (key.offset > bytenr && path->slots[0] > 0) {
				int slot = path->slots[0] - 1;

				while (slot >= 0) {
					struct btrfs_key pk;

					btrfs_item_key_to_cpu(leaf, &pk, slot);
					if (pk.offset < bytenr ||
					    pk.type != BTRFS_EXTENT_CSUM_KEY ||
					    pk.objectid !=
					    BTRFS_EXTENT_CSUM_OBJECTID)
						break;
					path->slots[0] = slot;
					del_nr++;
					key.offset = pk.offset;
					slot--;
				}
			}
			ret = btrfs_del_items(trans, root, path,
					      path->slots[0], del_nr);
			if (ret)
				break;
			if (key.offset == bytenr)
				break;
		} else if (key.offset < bytenr && csum_end > end_byte) {
			unsigned long offset;
			unsigned long shift_len;
			unsigned long item_offset;
			/*
			 *        [ bytenr - len ]
			 *     [csum                ]
			 *
			 * Our bytes are in the middle of the csum,
			 * we need to split this item and insert a new one.
			 *
			 * But we can't drop the path because the
			 * csum could change, get removed, extended etc.
			 *
			 * The trick here is the max size of a csum item leaves
			 * enough room in the tree block for a single
			 * item header.  So, we split the item in place,
			 * adding a new header pointing to the existing
			 * bytes.  Then we loop around again and we have
			 * a nicely formed csum item that we can neatly
			 * truncate.
			 */
			offset = (bytenr - key.offset) >> blocksize_bits;
			offset *= csum_size;

			shift_len = (len >> blocksize_bits) * csum_size;

			item_offset = btrfs_item_ptr_offset(leaf,
							    path->slots[0]);

			memzero_extent_buffer(leaf, item_offset + offset,
					     shift_len);
			key.offset = bytenr;

			/*
			 * btrfs_split_item returns -EAGAIN when the
			 * item changed size or key
			 */
			ret = btrfs_split_item(trans, root, path, &key, offset);
			if (ret && ret != -EAGAIN) {
				btrfs_abort_transaction(trans, ret);
				break;
			}
			ret = 0;

			key.offset = end_byte - 1;
		} else {
			truncate_one_csum(trans, path, &key, bytenr, len);
			if (key.offset < bytenr)
				break;
		}
		btrfs_release_path(path);
	}
	btrfs_free_path(path);
	return ret;
}

static int find_next_csum_offset(struct btrfs_root *root,
				 struct btrfs_path *path,
				 u64 *next_offset)
{
	const u32 nritems = btrfs_header_nritems(path->nodes[0]);
	struct btrfs_key found_key;
	int slot = path->slots[0] + 1;
	int ret;

	if (nritems == 0 || slot >= nritems) {
		ret = btrfs_next_leaf(root, path);
		if (ret < 0) {
			return ret;
		} else if (ret > 0) {
			*next_offset = (u64)-1;
			return 0;
		}
		slot = path->slots[0];
	}

	btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);

	if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
	    found_key.type != BTRFS_EXTENT_CSUM_KEY)
		*next_offset = (u64)-1;
	else
		*next_offset = found_key.offset;

	return 0;
}

int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
			   struct btrfs_root *root,
			   struct btrfs_ordered_sum *sums)
{
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct btrfs_key file_key;
	struct btrfs_key found_key;
	struct btrfs_path *path;
	struct btrfs_csum_item *item;
	struct btrfs_csum_item *item_end;
	struct extent_buffer *leaf = NULL;
	u64 next_offset;
	u64 total_bytes = 0;
	u64 csum_offset;
	u64 bytenr;
	u32 ins_size;
	int index = 0;
	int found_next;
	int ret;
	const u32 csum_size = fs_info->csum_size;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
again:
	next_offset = (u64)-1;
	found_next = 0;
	bytenr = sums->logical + total_bytes;
	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
	file_key.offset = bytenr;
	file_key.type = BTRFS_EXTENT_CSUM_KEY;

	item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
	if (!IS_ERR(item)) {
		ret = 0;
		leaf = path->nodes[0];
		item_end = btrfs_item_ptr(leaf, path->slots[0],
					  struct btrfs_csum_item);
		item_end = (struct btrfs_csum_item *)((char *)item_end +
			   btrfs_item_size(leaf, path->slots[0]));
		goto found;
	}
	ret = PTR_ERR(item);
	if (ret != -EFBIG && ret != -ENOENT)
		goto out;

	if (ret == -EFBIG) {
		u32 item_size;
		/* we found one, but it isn't big enough yet */
		leaf = path->nodes[0];
		item_size = btrfs_item_size(leaf, path->slots[0]);
		if ((item_size / csum_size) >=
		    MAX_CSUM_ITEMS(fs_info, csum_size)) {
			/* already at max size, make a new one */
			goto insert;
		}
	} else {
		/* We didn't find a csum item, insert one. */
		ret = find_next_csum_offset(root, path, &next_offset);
		if (ret < 0)
			goto out;
		found_next = 1;
		goto insert;
	}

	/*
	 * At this point, we know the tree has a checksum item that ends at an
	 * offset matching the start of the checksum range we want to insert.
	 * We try to extend that item as much as possible and then add as many
	 * checksums to it as they fit.
	 *
	 * First check if the leaf has enough free space for at least one
	 * checksum. If it has go directly to the item extension code, otherwise
	 * release the path and do a search for insertion before the extension.
	 */
	if (btrfs_leaf_free_space(leaf) >= csum_size) {
		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
		csum_offset = (bytenr - found_key.offset) >>
			fs_info->sectorsize_bits;
		goto extend_csum;
	}

	btrfs_release_path(path);
	path->search_for_extension = 1;
	ret = btrfs_search_slot(trans, root, &file_key, path,
				csum_size, 1);
	path->search_for_extension = 0;
	if (ret < 0)
		goto out;

	if (ret > 0) {
		if (path->slots[0] == 0)
			goto insert;
		path->slots[0]--;
	}

	leaf = path->nodes[0];
	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
	csum_offset = (bytenr - found_key.offset) >> fs_info->sectorsize_bits;

	if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
	    found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
	    csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
		goto insert;
	}

extend_csum:
	if (csum_offset == btrfs_item_size(leaf, path->slots[0]) /
	    csum_size) {
		int extend_nr;
		u64 tmp;
		u32 diff;

		tmp = sums->len - total_bytes;
		tmp >>= fs_info->sectorsize_bits;
		WARN_ON(tmp < 1);
		extend_nr = max_t(int, 1, tmp);

		/*
		 * A log tree can already have checksum items with a subset of
		 * the checksums we are trying to log. This can happen after
		 * doing a sequence of partial writes into prealloc extents and
		 * fsyncs in between, with a full fsync logging a larger subrange
		 * of an extent for which a previous fast fsync logged a smaller
		 * subrange. And this happens in particular due to merging file
		 * extent items when we complete an ordered extent for a range
		 * covered by a prealloc extent - this is done at
		 * btrfs_mark_extent_written().
		 *
		 * So if we try to extend the previous checksum item, which has
		 * a range that ends at the start of the range we want to insert,
		 * make sure we don't extend beyond the start offset of the next
		 * checksum item. If we are at the last item in the leaf, then
		 * forget the optimization of extending and add a new checksum
		 * item - it is not worth the complexity of releasing the path,
		 * getting the first key for the next leaf, repeat the btree
		 * search, etc, because log trees are temporary anyway and it
		 * would only save a few bytes of leaf space.
		 */
		if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
			if (path->slots[0] + 1 >=
			    btrfs_header_nritems(path->nodes[0])) {
				ret = find_next_csum_offset(root, path, &next_offset);
				if (ret < 0)
					goto out;
				found_next = 1;
				goto insert;
			}

			ret = find_next_csum_offset(root, path, &next_offset);
			if (ret < 0)
				goto out;

			tmp = (next_offset - bytenr) >> fs_info->sectorsize_bits;
			if (tmp <= INT_MAX)
				extend_nr = min_t(int, extend_nr, tmp);
		}

		diff = (csum_offset + extend_nr) * csum_size;
		diff = min(diff,
			   MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);

		diff = diff - btrfs_item_size(leaf, path->slots[0]);
		diff = min_t(u32, btrfs_leaf_free_space(leaf), diff);
		diff /= csum_size;
		diff *= csum_size;

		btrfs_extend_item(trans, path, diff);
		ret = 0;
		goto csum;
	}

insert:
	btrfs_release_path(path);
	csum_offset = 0;
	if (found_next) {
		u64 tmp;

		tmp = sums->len - total_bytes;
		tmp >>= fs_info->sectorsize_bits;
		tmp = min(tmp, (next_offset - file_key.offset) >>
					 fs_info->sectorsize_bits);

		tmp = max_t(u64, 1, tmp);
		tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
		ins_size = csum_size * tmp;
	} else {
		ins_size = csum_size;
	}
	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
				      ins_size);
	if (ret < 0)
		goto out;
	if (WARN_ON(ret != 0))
		goto out;
	leaf = path->nodes[0];
csum:
	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
	item_end = (struct btrfs_csum_item *)((unsigned char *)item +
				      btrfs_item_size(leaf, path->slots[0]));
	item = (struct btrfs_csum_item *)((unsigned char *)item +
					  csum_offset * csum_size);
found:
	ins_size = (u32)(sums->len - total_bytes) >> fs_info->sectorsize_bits;
	ins_size *= csum_size;
	ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
			      ins_size);
	write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
			    ins_size);

	index += ins_size;
	ins_size /= csum_size;
	total_bytes += ins_size * fs_info->sectorsize;

	btrfs_mark_buffer_dirty(trans, path->nodes[0]);
	if (total_bytes < sums->len) {
		btrfs_release_path(path);
		cond_resched();
		goto again;
	}
out:
	btrfs_free_path(path);
	return ret;
}

void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
				     const struct btrfs_path *path,
				     struct btrfs_file_extent_item *fi,
				     struct extent_map *em)
{
	struct btrfs_fs_info *fs_info = inode->root->fs_info;
	struct btrfs_root *root = inode->root;
	struct extent_buffer *leaf = path->nodes[0];
	const int slot = path->slots[0];
	struct btrfs_key key;
	u64 extent_start, extent_end;
	u64 bytenr;
	u8 type = btrfs_file_extent_type(leaf, fi);
	int compress_type = btrfs_file_extent_compression(leaf, fi);

	btrfs_item_key_to_cpu(leaf, &key, slot);
	extent_start = key.offset;
	extent_end = btrfs_file_extent_end(path);
	em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
	em->generation = btrfs_file_extent_generation(leaf, fi);
	if (type == BTRFS_FILE_EXTENT_REG ||
	    type == BTRFS_FILE_EXTENT_PREALLOC) {
		em->start = extent_start;
		em->len = extent_end - extent_start;
		em->orig_start = extent_start -
			btrfs_file_extent_offset(leaf, fi);
		em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
		if (bytenr == 0) {
			em->block_start = EXTENT_MAP_HOLE;
			return;
		}
		if (compress_type != BTRFS_COMPRESS_NONE) {
			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
			em->compress_type = compress_type;
			em->block_start = bytenr;
			em->block_len = em->orig_block_len;
		} else {
			bytenr += btrfs_file_extent_offset(leaf, fi);
			em->block_start = bytenr;
			em->block_len = em->len;
			if (type == BTRFS_FILE_EXTENT_PREALLOC)
				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
		}
	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
		em->block_start = EXTENT_MAP_INLINE;
		em->start = extent_start;
		em->len = extent_end - extent_start;
		/*
		 * Initialize orig_start and block_len with the same values
		 * as in inode.c:btrfs_get_extent().
		 */
		em->orig_start = EXTENT_MAP_HOLE;
		em->block_len = (u64)-1;
		em->compress_type = compress_type;
		if (compress_type != BTRFS_COMPRESS_NONE)
			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
	} else {
		btrfs_err(fs_info,
			  "unknown file extent item type %d, inode %llu, offset %llu, "
			  "root %llu", type, btrfs_ino(inode), extent_start,
			  root->root_key.objectid);
	}
}

/*
 * Returns the end offset (non inclusive) of the file extent item the given path
 * points to. If it points to an inline extent, the returned offset is rounded
 * up to the sector size.
 */
u64 btrfs_file_extent_end(const struct btrfs_path *path)
{
	const struct extent_buffer *leaf = path->nodes[0];
	const int slot = path->slots[0];
	struct btrfs_file_extent_item *fi;
	struct btrfs_key key;
	u64 end;

	btrfs_item_key_to_cpu(leaf, &key, slot);
	ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);

	if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
		end = btrfs_file_extent_ram_bytes(leaf, fi);
		end = ALIGN(key.offset + end, leaf->fs_info->sectorsize);
	} else {
		end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
	}

	return end;
}