summaryrefslogtreecommitdiffstats
path: root/fs/gfs2/bmap.c
blob: e6ee5b6e8d99379e97cf5d777892dbd1065e595d (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
/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>

#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "log.h"
#include "super.h"
#include "trans.h"
#include "dir.h"
#include "util.h"
#include "trace_gfs2.h"

/* This doesn't need to be that large as max 64 bit pointers in a 4k
 * block is 512, so __u16 is fine for that. It saves stack space to
 * keep it small.
 */
struct metapath {
	struct buffer_head *mp_bh[GFS2_MAX_META_HEIGHT];
	__u16 mp_list[GFS2_MAX_META_HEIGHT];
};

struct strip_mine {
	int sm_first;
	unsigned int sm_height;
};

/**
 * gfs2_unstuffer_page - unstuff a stuffed inode into a block cached by a page
 * @ip: the inode
 * @dibh: the dinode buffer
 * @block: the block number that was allocated
 * @page: The (optional) page. This is looked up if @page is NULL
 *
 * Returns: errno
 */

static int gfs2_unstuffer_page(struct gfs2_inode *ip, struct buffer_head *dibh,
			       u64 block, struct page *page)
{
	struct inode *inode = &ip->i_inode;
	struct buffer_head *bh;
	int release = 0;

	if (!page || page->index) {
		page = find_or_create_page(inode->i_mapping, 0, GFP_NOFS);
		if (!page)
			return -ENOMEM;
		release = 1;
	}

	if (!PageUptodate(page)) {
		void *kaddr = kmap(page);
		u64 dsize = i_size_read(inode);
 
		if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
			dsize = dibh->b_size - sizeof(struct gfs2_dinode);

		memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
		memset(kaddr + dsize, 0, PAGE_CACHE_SIZE - dsize);
		kunmap(page);

		SetPageUptodate(page);
	}

	if (!page_has_buffers(page))
		create_empty_buffers(page, 1 << inode->i_blkbits,
				     (1 << BH_Uptodate));

	bh = page_buffers(page);

	if (!buffer_mapped(bh))
		map_bh(bh, inode->i_sb, block);

	set_buffer_uptodate(bh);
	if (!gfs2_is_jdata(ip))
		mark_buffer_dirty(bh);
	if (!gfs2_is_writeback(ip))
		gfs2_trans_add_data(ip->i_gl, bh);

	if (release) {
		unlock_page(page);
		page_cache_release(page);
	}

	return 0;
}

/**
 * gfs2_unstuff_dinode - Unstuff a dinode when the data has grown too big
 * @ip: The GFS2 inode to unstuff
 * @page: The (optional) page. This is looked up if the @page is NULL
 *
 * This routine unstuffs a dinode and returns it to a "normal" state such
 * that the height can be grown in the traditional way.
 *
 * Returns: errno
 */

int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page)
{
	struct buffer_head *bh, *dibh;
	struct gfs2_dinode *di;
	u64 block = 0;
	int isdir = gfs2_is_dir(ip);
	int error;

	down_write(&ip->i_rw_mutex);

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out;

	if (i_size_read(&ip->i_inode)) {
		/* Get a free block, fill it with the stuffed data,
		   and write it out to disk */

		unsigned int n = 1;
		error = gfs2_alloc_blocks(ip, &block, &n, 0, NULL);
		if (error)
			goto out_brelse;
		if (isdir) {
			gfs2_trans_add_unrevoke(GFS2_SB(&ip->i_inode), block, 1);
			error = gfs2_dir_get_new_buffer(ip, block, &bh);
			if (error)
				goto out_brelse;
			gfs2_buffer_copy_tail(bh, sizeof(struct gfs2_meta_header),
					      dibh, sizeof(struct gfs2_dinode));
			brelse(bh);
		} else {
			error = gfs2_unstuffer_page(ip, dibh, block, page);
			if (error)
				goto out_brelse;
		}
	}

	/*  Set up the pointer to the new block  */

	gfs2_trans_add_meta(ip->i_gl, dibh);
	di = (struct gfs2_dinode *)dibh->b_data;
	gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));

	if (i_size_read(&ip->i_inode)) {
		*(__be64 *)(di + 1) = cpu_to_be64(block);
		gfs2_add_inode_blocks(&ip->i_inode, 1);
		di->di_blocks = cpu_to_be64(gfs2_get_inode_blocks(&ip->i_inode));
	}

	ip->i_height = 1;
	di->di_height = cpu_to_be16(1);

out_brelse:
	brelse(dibh);
out:
	up_write(&ip->i_rw_mutex);
	return error;
}


/**
 * find_metapath - Find path through the metadata tree
 * @sdp: The superblock
 * @mp: The metapath to return the result in
 * @block: The disk block to look up
 * @height: The pre-calculated height of the metadata tree
 *
 *   This routine returns a struct metapath structure that defines a path
 *   through the metadata of inode "ip" to get to block "block".
 *
 *   Example:
 *   Given:  "ip" is a height 3 file, "offset" is 101342453, and this is a
 *   filesystem with a blocksize of 4096.
 *
 *   find_metapath() would return a struct metapath structure set to:
 *   mp_offset = 101342453, mp_height = 3, mp_list[0] = 0, mp_list[1] = 48,
 *   and mp_list[2] = 165.
 *
 *   That means that in order to get to the block containing the byte at
 *   offset 101342453, we would load the indirect block pointed to by pointer
 *   0 in the dinode.  We would then load the indirect block pointed to by
 *   pointer 48 in that indirect block.  We would then load the data block
 *   pointed to by pointer 165 in that indirect block.
 *
 *             ----------------------------------------
 *             | Dinode |                             |
 *             |        |                            4|
 *             |        |0 1 2 3 4 5                 9|
 *             |        |                            6|
 *             ----------------------------------------
 *                       |
 *                       |
 *                       V
 *             ----------------------------------------
 *             | Indirect Block                       |
 *             |                                     5|
 *             |            4 4 4 4 4 5 5            1|
 *             |0           5 6 7 8 9 0 1            2|
 *             ----------------------------------------
 *                                |
 *                                |
 *                                V
 *             ----------------------------------------
 *             | Indirect Block                       |
 *             |                         1 1 1 1 1   5|
 *             |                         6 6 6 6 6   1|
 *             |0                        3 4 5 6 7   2|
 *             ----------------------------------------
 *                                           |
 *                                           |
 *                                           V
 *             ----------------------------------------
 *             | Data block containing offset         |
 *             |            101342453                 |
 *             |                                      |
 *             |                                      |
 *             ----------------------------------------
 *
 */

static void find_metapath(const struct gfs2_sbd *sdp, u64 block,
			  struct metapath *mp, unsigned int height)
{
	unsigned int i;

	for (i = height; i--;)
		mp->mp_list[i] = do_div(block, sdp->sd_inptrs);

}

static inline unsigned int metapath_branch_start(const struct metapath *mp)
{
	if (mp->mp_list[0] == 0)
		return 2;
	return 1;
}

/**
 * metapointer - Return pointer to start of metadata in a buffer
 * @height: The metadata height (0 = dinode)
 * @mp: The metapath
 *
 * Return a pointer to the block number of the next height of the metadata
 * tree given a buffer containing the pointer to the current height of the
 * metadata tree.
 */

static inline __be64 *metapointer(unsigned int height, const struct metapath *mp)
{
	struct buffer_head *bh = mp->mp_bh[height];
	unsigned int head_size = (height > 0) ?
		sizeof(struct gfs2_meta_header) : sizeof(struct gfs2_dinode);
	return ((__be64 *)(bh->b_data + head_size)) + mp->mp_list[height];
}

static void gfs2_metapath_ra(struct gfs2_glock *gl,
			     const struct buffer_head *bh, const __be64 *pos)
{
	struct buffer_head *rabh;
	const __be64 *endp = (const __be64 *)(bh->b_data + bh->b_size);
	const __be64 *t;

	for (t = pos; t < endp; t++) {
		if (!*t)
			continue;

		rabh = gfs2_getbuf(gl, be64_to_cpu(*t), CREATE);
		if (trylock_buffer(rabh)) {
			if (!buffer_uptodate(rabh)) {
				rabh->b_end_io = end_buffer_read_sync;
				submit_bh(READA | REQ_META, rabh);
				continue;
			}
			unlock_buffer(rabh);
		}
		brelse(rabh);
	}
}

/**
 * lookup_metapath - Walk the metadata tree to a specific point
 * @ip: The inode
 * @mp: The metapath
 *
 * Assumes that the inode's buffer has already been looked up and
 * hooked onto mp->mp_bh[0] and that the metapath has been initialised
 * by find_metapath().
 *
 * If this function encounters part of the tree which has not been
 * allocated, it returns the current height of the tree at the point
 * at which it found the unallocated block. Blocks which are found are
 * added to the mp->mp_bh[] list.
 *
 * Returns: error or height of metadata tree
 */

static int lookup_metapath(struct gfs2_inode *ip, struct metapath *mp)
{
	unsigned int end_of_metadata = ip->i_height - 1;
	unsigned int x;
	__be64 *ptr;
	u64 dblock;
	int ret;

	for (x = 0; x < end_of_metadata; x++) {
		ptr = metapointer(x, mp);
		dblock = be64_to_cpu(*ptr);
		if (!dblock)
			return x + 1;

		ret = gfs2_meta_indirect_buffer(ip, x+1, dblock, &mp->mp_bh[x+1]);
		if (ret)
			return ret;
	}

	return ip->i_height;
}

static inline void release_metapath(struct metapath *mp)
{
	int i;

	for (i = 0; i < GFS2_MAX_META_HEIGHT; i++) {
		if (mp->mp_bh[i] == NULL)
			break;
		brelse(mp->mp_bh[i]);
	}
}

/**
 * gfs2_extent_length - Returns length of an extent of blocks
 * @start: Start of the buffer
 * @len: Length of the buffer in bytes
 * @ptr: Current position in the buffer
 * @limit: Max extent length to return (0 = unlimited)
 * @eob: Set to 1 if we hit "end of block"
 *
 * If the first block is zero (unallocated) it will return the number of
 * unallocated blocks in the extent, otherwise it will return the number
 * of contiguous blocks in the extent.
 *
 * Returns: The length of the extent (minimum of one block)
 */

static inline unsigned int gfs2_extent_length(void *start, unsigned int len, __be64 *ptr, unsigned limit, int *eob)
{
	const __be64 *end = (start + len);
	const __be64 *first = ptr;
	u64 d = be64_to_cpu(*ptr);

	*eob = 0;
	do {
		ptr++;
		if (ptr >= end)
			break;
		if (limit && --limit == 0)
			break;
		if (d)
			d++;
	} while(be64_to_cpu(*ptr) == d);
	if (ptr >= end)
		*eob = 1;
	return (ptr - first);
}

static inline void bmap_lock(struct gfs2_inode *ip, int create)
{
	if (create)
		down_write(&ip->i_rw_mutex);
	else
		down_read(&ip->i_rw_mutex);
}

static inline void bmap_unlock(struct gfs2_inode *ip, int create)
{
	if (create)
		up_write(&ip->i_rw_mutex);
	else
		up_read(&ip->i_rw_mutex);
}

static inline __be64 *gfs2_indirect_init(struct metapath *mp,
					 struct gfs2_glock *gl, unsigned int i,
					 unsigned offset, u64 bn)
{
	__be64 *ptr = (__be64 *)(mp->mp_bh[i - 1]->b_data +
		       ((i > 1) ? sizeof(struct gfs2_meta_header) :
				 sizeof(struct gfs2_dinode)));
	BUG_ON(i < 1);
	BUG_ON(mp->mp_bh[i] != NULL);
	mp->mp_bh[i] = gfs2_meta_new(gl, bn);
	gfs2_trans_add_meta(gl, mp->mp_bh[i]);
	gfs2_metatype_set(mp->mp_bh[i], GFS2_METATYPE_IN, GFS2_FORMAT_IN);
	gfs2_buffer_clear_tail(mp->mp_bh[i], sizeof(struct gfs2_meta_header));
	ptr += offset;
	*ptr = cpu_to_be64(bn);
	return ptr;
}

enum alloc_state {
	ALLOC_DATA = 0,
	ALLOC_GROW_DEPTH = 1,
	ALLOC_GROW_HEIGHT = 2,
	/* ALLOC_UNSTUFF = 3,   TBD and rather complicated */
};

/**
 * gfs2_bmap_alloc - Build a metadata tree of the requested height
 * @inode: The GFS2 inode
 * @lblock: The logical starting block of the extent
 * @bh_map: This is used to return the mapping details
 * @mp: The metapath
 * @sheight: The starting height (i.e. whats already mapped)
 * @height: The height to build to
 * @maxlen: The max number of data blocks to alloc
 *
 * In this routine we may have to alloc:
 *   i) Indirect blocks to grow the metadata tree height
 *  ii) Indirect blocks to fill in lower part of the metadata tree
 * iii) Data blocks
 *
 * The function is in two parts. The first part works out the total
 * number of blocks which we need. The second part does the actual
 * allocation asking for an extent at a time (if enough contiguous free
 * blocks are available, there will only be one request per bmap call)
 * and uses the state machine to initialise the blocks in order.
 *
 * Returns: errno on error
 */

static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
			   struct buffer_head *bh_map, struct metapath *mp,
			   const unsigned int sheight,
			   const unsigned int height,
			   const unsigned int maxlen)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct super_block *sb = sdp->sd_vfs;
	struct buffer_head *dibh = mp->mp_bh[0];
	u64 bn, dblock = 0;
	unsigned n, i, blks, alloced = 0, iblks = 0, branch_start = 0;
	unsigned dblks = 0;
	unsigned ptrs_per_blk;
	const unsigned end_of_metadata = height - 1;
	int ret;
	int eob = 0;
	enum alloc_state state;
	__be64 *ptr;
	__be64 zero_bn = 0;

	BUG_ON(sheight < 1);
	BUG_ON(dibh == NULL);

	gfs2_trans_add_meta(ip->i_gl, dibh);

	if (height == sheight) {
		struct buffer_head *bh;
		/* Bottom indirect block exists, find unalloced extent size */
		ptr = metapointer(end_of_metadata, mp);
		bh = mp->mp_bh[end_of_metadata];
		dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen,
					   &eob);
		BUG_ON(dblks < 1);
		state = ALLOC_DATA;
	} else {
		/* Need to allocate indirect blocks */
		ptrs_per_blk = height > 1 ? sdp->sd_inptrs : sdp->sd_diptrs;
		dblks = min(maxlen, ptrs_per_blk - mp->mp_list[end_of_metadata]);
		if (height == ip->i_height) {
			/* Writing into existing tree, extend tree down */
			iblks = height - sheight;
			state = ALLOC_GROW_DEPTH;
		} else {
			/* Building up tree height */
			state = ALLOC_GROW_HEIGHT;
			iblks = height - ip->i_height;
			branch_start = metapath_branch_start(mp);
			iblks += (height - branch_start);
		}
	}

	/* start of the second part of the function (state machine) */

	blks = dblks + iblks;
	i = sheight;
	do {
		int error;
		n = blks - alloced;
		error = gfs2_alloc_blocks(ip, &bn, &n, 0, NULL);
		if (error)
			return error;
		alloced += n;
		if (state != ALLOC_DATA || gfs2_is_jdata(ip))
			gfs2_trans_add_unrevoke(sdp, bn, n);
		switch (state) {
		/* Growing height of tree */
		case ALLOC_GROW_HEIGHT:
			if (i == 1) {
				ptr = (__be64 *)(dibh->b_data +
						 sizeof(struct gfs2_dinode));
				zero_bn = *ptr;
			}
			for (; i - 1 < height - ip->i_height && n > 0; i++, n--)
				gfs2_indirect_init(mp, ip->i_gl, i, 0, bn++);
			if (i - 1 == height - ip->i_height) {
				i--;
				gfs2_buffer_copy_tail(mp->mp_bh[i],
						sizeof(struct gfs2_meta_header),
						dibh, sizeof(struct gfs2_dinode));
				gfs2_buffer_clear_tail(dibh,
						sizeof(struct gfs2_dinode) +
						sizeof(__be64));
				ptr = (__be64 *)(mp->mp_bh[i]->b_data +
					sizeof(struct gfs2_meta_header));
				*ptr = zero_bn;
				state = ALLOC_GROW_DEPTH;
				for(i = branch_start; i < height; i++) {
					if (mp->mp_bh[i] == NULL)
						break;
					brelse(mp->mp_bh[i]);
					mp->mp_bh[i] = NULL;
				}
				i = branch_start;
			}
			if (n == 0)
				break;
		/* Branching from existing tree */
		case ALLOC_GROW_DEPTH:
			if (i > 1 && i < height)
				gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[i-1]);
			for (; i < height && n > 0; i++, n--)
				gfs2_indirect_init(mp, ip->i_gl, i,
						   mp->mp_list[i-1], bn++);
			if (i == height)
				state = ALLOC_DATA;
			if (n == 0)
				break;
		/* Tree complete, adding data blocks */
		case ALLOC_DATA:
			BUG_ON(n > dblks);
			BUG_ON(mp->mp_bh[end_of_metadata] == NULL);
			gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[end_of_metadata]);
			dblks = n;
			ptr = metapointer(end_of_metadata, mp);
			dblock = bn;
			while (n-- > 0)
				*ptr++ = cpu_to_be64(bn++);
			if (buffer_zeronew(bh_map)) {
				ret = sb_issue_zeroout(sb, dblock, dblks,
						       GFP_NOFS);
				if (ret) {
					fs_err(sdp,
					       "Failed to zero data buffers\n");
					clear_buffer_zeronew(bh_map);
				}
			}
			break;
		}
	} while ((state != ALLOC_DATA) || !dblock);

	ip->i_height = height;
	gfs2_add_inode_blocks(&ip->i_inode, alloced);
	gfs2_dinode_out(ip, mp->mp_bh[0]->b_data);
	map_bh(bh_map, inode->i_sb, dblock);
	bh_map->b_size = dblks << inode->i_blkbits;
	set_buffer_new(bh_map);
	return 0;
}

/**
 * gfs2_block_map - Map a block from an inode to a disk block
 * @inode: The inode
 * @lblock: The logical block number
 * @bh_map: The bh to be mapped
 * @create: True if its ok to alloc blocks to satify the request
 *
 * Sets buffer_mapped() if successful, sets buffer_boundary() if a
 * read of metadata will be required before the next block can be
 * mapped. Sets buffer_new() if new blocks were allocated.
 *
 * Returns: errno
 */

int gfs2_block_map(struct inode *inode, sector_t lblock,
		   struct buffer_head *bh_map, int create)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	unsigned int bsize = sdp->sd_sb.sb_bsize;
	const unsigned int maxlen = bh_map->b_size >> inode->i_blkbits;
	const u64 *arr = sdp->sd_heightsize;
	__be64 *ptr;
	u64 size;
	struct metapath mp;
	int ret;
	int eob;
	unsigned int len;
	struct buffer_head *bh;
	u8 height;

	BUG_ON(maxlen == 0);

	memset(mp.mp_bh, 0, sizeof(mp.mp_bh));
	bmap_lock(ip, create);
	clear_buffer_mapped(bh_map);
	clear_buffer_new(bh_map);
	clear_buffer_boundary(bh_map);
	trace_gfs2_bmap(ip, bh_map, lblock, create, 1);
	if (gfs2_is_dir(ip)) {
		bsize = sdp->sd_jbsize;
		arr = sdp->sd_jheightsize;
	}

	ret = gfs2_meta_inode_buffer(ip, &mp.mp_bh[0]);
	if (ret)
		goto out;

	height = ip->i_height;
	size = (lblock + 1) * bsize;
	while (size > arr[height])
		height++;
	find_metapath(sdp, lblock, &mp, height);
	ret = 1;
	if (height > ip->i_height || gfs2_is_stuffed(ip))
		goto do_alloc;
	ret = lookup_metapath(ip, &mp);
	if (ret < 0)
		goto out;
	if (ret != ip->i_height)
		goto do_alloc;
	ptr = metapointer(ip->i_height - 1, &mp);
	if (*ptr == 0)
		goto do_alloc;
	map_bh(bh_map, inode->i_sb, be64_to_cpu(*ptr));
	bh = mp.mp_bh[ip->i_height - 1];
	len = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen, &eob);
	bh_map->b_size = (len << inode->i_blkbits);
	if (eob)
		set_buffer_boundary(bh_map);
	ret = 0;
out:
	release_metapath(&mp);
	trace_gfs2_bmap(ip, bh_map, lblock, create, ret);
	bmap_unlock(ip, create);
	return ret;

do_alloc:
	/* All allocations are done here, firstly check create flag */
	if (!create) {
		BUG_ON(gfs2_is_stuffed(ip));
		ret = 0;
		goto out;
	}

	/* At this point ret is the tree depth of already allocated blocks */
	ret = gfs2_bmap_alloc(inode, lblock, bh_map, &mp, ret, height, maxlen);
	goto out;
}

/*
 * Deprecated: do not use in new code
 */
int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsigned *extlen)
{
	struct buffer_head bh = { .b_state = 0, .b_blocknr = 0 };
	int ret;
	int create = *new;

	BUG_ON(!extlen);
	BUG_ON(!dblock);
	BUG_ON(!new);

	bh.b_size = 1 << (inode->i_blkbits + (create ? 0 : 5));
	ret = gfs2_block_map(inode, lblock, &bh, create);
	*extlen = bh.b_size >> inode->i_blkbits;
	*dblock = bh.b_blocknr;
	if (buffer_new(&bh))
		*new = 1;
	else
		*new = 0;
	return ret;
}

/**
 * do_strip - Look for a layer a particular layer of the file and strip it off
 * @ip: the inode
 * @dibh: the dinode buffer
 * @bh: A buffer of pointers
 * @top: The first pointer in the buffer
 * @bottom: One more than the last pointer
 * @height: the height this buffer is at
 * @sm: a pointer to a struct strip_mine
 *
 * Returns: errno
 */

static int do_strip(struct gfs2_inode *ip, struct buffer_head *dibh,
		    struct buffer_head *bh, __be64 *top, __be64 *bottom,
		    unsigned int height, struct strip_mine *sm)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_rgrp_list rlist;
	u64 bn, bstart;
	u32 blen, btotal;
	__be64 *p;
	unsigned int rg_blocks = 0;
	int metadata;
	unsigned int revokes = 0;
	int x;
	int error;

	error = gfs2_rindex_update(sdp);
	if (error)
		return error;

	if (!*top)
		sm->sm_first = 0;

	if (height != sm->sm_height)
		return 0;

	if (sm->sm_first) {
		top++;
		sm->sm_first = 0;
	}

	metadata = (height != ip->i_height - 1);
	if (metadata)
		revokes = (height) ? sdp->sd_inptrs : sdp->sd_diptrs;
	else if (ip->i_depth)
		revokes = sdp->sd_inptrs;

	memset(&rlist, 0, sizeof(struct gfs2_rgrp_list));
	bstart = 0;
	blen = 0;

	for (p = top; p < bottom; p++) {
		if (!*p)
			continue;

		bn = be64_to_cpu(*p);

		if (bstart + blen == bn)
			blen++;
		else {
			if (bstart)
				gfs2_rlist_add(ip, &rlist, bstart);

			bstart = bn;
			blen = 1;
		}
	}

	if (bstart)
		gfs2_rlist_add(ip, &rlist, bstart);
	else
		goto out; /* Nothing to do */

	gfs2_rlist_alloc(&rlist, LM_ST_EXCLUSIVE);

	for (x = 0; x < rlist.rl_rgrps; x++) {
		struct gfs2_rgrpd *rgd;
		rgd = rlist.rl_ghs[x].gh_gl->gl_object;
		rg_blocks += rgd->rd_length;
	}

	error = gfs2_glock_nq_m(rlist.rl_rgrps, rlist.rl_ghs);
	if (error)
		goto out_rlist;

	if (gfs2_rs_active(ip->i_res)) /* needs to be done with the rgrp glock held */
		gfs2_rs_deltree(ip->i_res);

	error = gfs2_trans_begin(sdp, rg_blocks + RES_DINODE +
				 RES_INDIRECT + RES_STATFS + RES_QUOTA,
				 revokes);
	if (error)
		goto out_rg_gunlock;

	down_write(&ip->i_rw_mutex);

	gfs2_trans_add_meta(ip->i_gl, dibh);
	gfs2_trans_add_meta(ip->i_gl, bh);

	bstart = 0;
	blen = 0;
	btotal = 0;

	for (p = top; p < bottom; p++) {
		if (!*p)
			continue;

		bn = be64_to_cpu(*p);

		if (bstart + blen == bn)
			blen++;
		else {
			if (bstart) {
				__gfs2_free_blocks(ip, bstart, blen, metadata);
				btotal += blen;
			}

			bstart = bn;
			blen = 1;
		}

		*p = 0;
		gfs2_add_inode_blocks(&ip->i_inode, -1);
	}
	if (bstart) {
		__gfs2_free_blocks(ip, bstart, blen, metadata);
		btotal += blen;
	}

	gfs2_statfs_change(sdp, 0, +btotal, 0);
	gfs2_quota_change(ip, -(s64)btotal, ip->i_inode.i_uid,
			  ip->i_inode.i_gid);

	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;

	gfs2_dinode_out(ip, dibh->b_data);

	up_write(&ip->i_rw_mutex);

	gfs2_trans_end(sdp);

out_rg_gunlock:
	gfs2_glock_dq_m(rlist.rl_rgrps, rlist.rl_ghs);
out_rlist:
	gfs2_rlist_free(&rlist);
out:
	return error;
}

/**
 * recursive_scan - recursively scan through the end of a file
 * @ip: the inode
 * @dibh: the dinode buffer
 * @mp: the path through the metadata to the point to start
 * @height: the height the recursion is at
 * @block: the indirect block to look at
 * @first: 1 if this is the first block
 * @sm: data opaque to this function to pass to @bc
 *
 * When this is first called @height and @block should be zero and
 * @first should be 1.
 *
 * Returns: errno
 */

static int recursive_scan(struct gfs2_inode *ip, struct buffer_head *dibh,
			  struct metapath *mp, unsigned int height,
			  u64 block, int first, struct strip_mine *sm)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *bh = NULL;
	__be64 *top, *bottom;
	u64 bn;
	int error;
	int mh_size = sizeof(struct gfs2_meta_header);

	if (!height) {
		error = gfs2_meta_inode_buffer(ip, &bh);
		if (error)
			return error;
		dibh = bh;

		top = (__be64 *)(bh->b_data + sizeof(struct gfs2_dinode)) + mp->mp_list[0];
		bottom = (__be64 *)(bh->b_data + sizeof(struct gfs2_dinode)) + sdp->sd_diptrs;
	} else {
		error = gfs2_meta_indirect_buffer(ip, height, block, &bh);
		if (error)
			return error;

		top = (__be64 *)(bh->b_data + mh_size) +
				  (first ? mp->mp_list[height] : 0);

		bottom = (__be64 *)(bh->b_data + mh_size) + sdp->sd_inptrs;
	}

	error = do_strip(ip, dibh, bh, top, bottom, height, sm);
	if (error)
		goto out;

	if (height < ip->i_height - 1) {

		gfs2_metapath_ra(ip->i_gl, bh, top);

		for (; top < bottom; top++, first = 0) {
			if (!*top)
				continue;

			bn = be64_to_cpu(*top);

			error = recursive_scan(ip, dibh, mp, height + 1, bn,
					       first, sm);
			if (error)
				break;
		}
	}
out:
	brelse(bh);
	return error;
}


/**
 * gfs2_block_truncate_page - Deal with zeroing out data for truncate
 *
 * This is partly borrowed from ext3.
 */
static int gfs2_block_truncate_page(struct address_space *mapping, loff_t from)
{
	struct inode *inode = mapping->host;
	struct gfs2_inode *ip = GFS2_I(inode);
	unsigned long index = from >> PAGE_CACHE_SHIFT;
	unsigned offset = from & (PAGE_CACHE_SIZE-1);
	unsigned blocksize, iblock, length, pos;
	struct buffer_head *bh;
	struct page *page;
	int err;

	page = find_or_create_page(mapping, index, GFP_NOFS);
	if (!page)
		return 0;

	blocksize = inode->i_sb->s_blocksize;
	length = blocksize - (offset & (blocksize - 1));
	iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);

	if (!page_has_buffers(page))
		create_empty_buffers(page, blocksize, 0);

	/* Find the buffer that contains "offset" */
	bh = page_buffers(page);
	pos = blocksize;
	while (offset >= pos) {
		bh = bh->b_this_page;
		iblock++;
		pos += blocksize;
	}

	err = 0;

	if (!buffer_mapped(bh)) {
		gfs2_block_map(inode, iblock, bh, 0);
		/* unmapped? It's a hole - nothing to do */
		if (!buffer_mapped(bh))
			goto unlock;
	}

	/* Ok, it's mapped. Make sure it's up-to-date */
	if (PageUptodate(page))
		set_buffer_uptodate(bh);

	if (!buffer_uptodate(bh)) {
		err = -EIO;
		ll_rw_block(READ, 1, &bh);
		wait_on_buffer(bh);
		/* Uhhuh. Read error. Complain and punt. */
		if (!buffer_uptodate(bh))
			goto unlock;
		err = 0;
	}

	if (!gfs2_is_writeback(ip))
		gfs2_trans_add_data(ip->i_gl, bh);

	zero_user(page, offset, length);
	mark_buffer_dirty(bh);
unlock:
	unlock_page(page);
	page_cache_release(page);
	return err;
}

#define GFS2_JTRUNC_REVOKES 8192

/**
 * gfs2_journaled_truncate - Wrapper for truncate_pagecache for jdata files
 * @inode: The inode being truncated
 * @oldsize: The original (larger) size
 * @newsize: The new smaller size
 *
 * With jdata files, we have to journal a revoke for each block which is
 * truncated. As a result, we need to split this into separate transactions
 * if the number of pages being truncated gets too large.
 */

static int gfs2_journaled_truncate(struct inode *inode, u64 oldsize, u64 newsize)
{
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	u64 max_chunk = GFS2_JTRUNC_REVOKES * sdp->sd_vfs->s_blocksize;
	u64 chunk;
	int error;

	while (oldsize != newsize) {
		chunk = oldsize - newsize;
		if (chunk > max_chunk)
			chunk = max_chunk;
		truncate_pagecache(inode, oldsize - chunk);
		oldsize -= chunk;
		gfs2_trans_end(sdp);
		error = gfs2_trans_begin(sdp, RES_DINODE, GFS2_JTRUNC_REVOKES);
		if (error)
			return error;
	}

	return 0;
}

static int trunc_start(struct inode *inode, u64 oldsize, u64 newsize)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct address_space *mapping = inode->i_mapping;
	struct buffer_head *dibh;
	int journaled = gfs2_is_jdata(ip);
	int error;

	if (journaled)
		error = gfs2_trans_begin(sdp, RES_DINODE + RES_JDATA, GFS2_JTRUNC_REVOKES);
	else
		error = gfs2_trans_begin(sdp, RES_DINODE, 0);
	if (error)
		return error;

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out;

	gfs2_trans_add_meta(ip->i_gl, dibh);

	if (gfs2_is_stuffed(ip)) {
		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + newsize);
	} else {
		if (newsize & (u64)(sdp->sd_sb.sb_bsize - 1)) {
			error = gfs2_block_truncate_page(mapping, newsize);
			if (error)
				goto out_brelse;
		}
		ip->i_diskflags |= GFS2_DIF_TRUNC_IN_PROG;
	}

	i_size_write(inode, newsize);
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
	gfs2_dinode_out(ip, dibh->b_data);

	if (journaled)
		error = gfs2_journaled_truncate(inode, oldsize, newsize);
	else
		truncate_pagecache(inode, newsize);

	if (error) {
		brelse(dibh);
		return error;
	}

out_brelse:
	brelse(dibh);
out:
	gfs2_trans_end(sdp);
	return error;
}

static int trunc_dealloc(struct gfs2_inode *ip, u64 size)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	unsigned int height = ip->i_height;
	u64 lblock;
	struct metapath mp;
	int error;

	if (!size)
		lblock = 0;
	else
		lblock = (size - 1) >> sdp->sd_sb.sb_bsize_shift;

	find_metapath(sdp, lblock, &mp, ip->i_height);
	error = gfs2_rindex_update(sdp);
	if (error)
		return error;

	error = gfs2_quota_hold(ip, NO_UID_QUOTA_CHANGE, NO_GID_QUOTA_CHANGE);
	if (error)
		return error;

	while (height--) {
		struct strip_mine sm;
		sm.sm_first = !!size;
		sm.sm_height = height;

		error = recursive_scan(ip, NULL, &mp, 0, 0, 1, &sm);
		if (error)
			break;
	}

	gfs2_quota_unhold(ip);

	return error;
}

static int trunc_end(struct gfs2_inode *ip)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *dibh;
	int error;

	error = gfs2_trans_begin(sdp, RES_DINODE, 0);
	if (error)
		return error;

	down_write(&ip->i_rw_mutex);

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out;

	if (!i_size_read(&ip->i_inode)) {
		ip->i_height = 0;
		ip->i_goal = ip->i_no_addr;
		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
		gfs2_ordered_del_inode(ip);
	}
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
	ip->i_diskflags &= ~GFS2_DIF_TRUNC_IN_PROG;

	gfs2_trans_add_meta(ip->i_gl, dibh);
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

out:
	up_write(&ip->i_rw_mutex);
	gfs2_trans_end(sdp);
	return error;
}

/**
 * do_shrink - make a file smaller
 * @inode: the inode
 * @oldsize: the current inode size
 * @newsize: the size to make the file
 *
 * Called with an exclusive lock on @inode. The @size must
 * be equal to or smaller than the current inode size.
 *
 * Returns: errno
 */

static int do_shrink(struct inode *inode, u64 oldsize, u64 newsize)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	int error;

	error = trunc_start(inode, oldsize, newsize);
	if (error < 0)
		return error;
	if (gfs2_is_stuffed(ip))
		return 0;

	error = trunc_dealloc(ip, newsize);
	if (error == 0)
		error = trunc_end(ip);

	return error;
}

void gfs2_trim_blocks(struct inode *inode)
{
	u64 size = inode->i_size;
	int ret;

	ret = do_shrink(inode, size, size);
	WARN_ON(ret != 0);
}

/**
 * do_grow - Touch and update inode size
 * @inode: The inode
 * @size: The new size
 *
 * This function updates the timestamps on the inode and
 * may also increase the size of the inode. This function
 * must not be called with @size any smaller than the current
 * inode size.
 *
 * Although it is not strictly required to unstuff files here,
 * earlier versions of GFS2 have a bug in the stuffed file reading
 * code which will result in a buffer overrun if the size is larger
 * than the max stuffed file size. In order to prevent this from
 * occurring, such files are unstuffed, but in other cases we can
 * just update the inode size directly.
 *
 * Returns: 0 on success, or -ve on error
 */

static int do_grow(struct inode *inode, u64 size)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct gfs2_alloc_parms ap = { .target = 1, };
	struct buffer_head *dibh;
	int error;
	int unstuff = 0;

	if (gfs2_is_stuffed(ip) &&
	    (size > (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)))) {
		error = gfs2_quota_lock_check(ip);
		if (error)
			return error;

		error = gfs2_inplace_reserve(ip, &ap);
		if (error)
			goto do_grow_qunlock;
		unstuff = 1;
	}

	error = gfs2_trans_begin(sdp, RES_DINODE + RES_STATFS + RES_RG_BIT +
				 (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF ?
				  0 : RES_QUOTA), 0);
	if (error)
		goto do_grow_release;

	if (unstuff) {
		error = gfs2_unstuff_dinode(ip, NULL);
		if (error)
			goto do_end_trans;
	}

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto do_end_trans;

	i_size_write(inode, size);
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
	gfs2_trans_add_meta(ip->i_gl, dibh);
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

do_end_trans:
	gfs2_trans_end(sdp);
do_grow_release:
	if (unstuff) {
		gfs2_inplace_release(ip);
do_grow_qunlock:
		gfs2_quota_unlock(ip);
	}
	return error;
}

/**
 * gfs2_setattr_size - make a file a given size
 * @inode: the inode
 * @newsize: the size to make the file
 *
 * The file size can grow, shrink, or stay the same size. This
 * is called holding i_mutex and an exclusive glock on the inode
 * in question.
 *
 * Returns: errno
 */

int gfs2_setattr_size(struct inode *inode, u64 newsize)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	int ret;
	u64 oldsize;

	BUG_ON(!S_ISREG(inode->i_mode));

	ret = inode_newsize_ok(inode, newsize);
	if (ret)
		return ret;

	ret = get_write_access(inode);
	if (ret)
		return ret;

	inode_dio_wait(inode);

	ret = gfs2_rs_alloc(ip);
	if (ret)
		goto out;

	oldsize = inode->i_size;
	if (newsize >= oldsize) {
		ret = do_grow(inode, newsize);
		goto out;
	}

	gfs2_rs_deltree(ip->i_res);
	ret = do_shrink(inode, oldsize, newsize);
out:
	put_write_access(inode);
	return ret;
}

int gfs2_truncatei_resume(struct gfs2_inode *ip)
{
	int error;
	error = trunc_dealloc(ip, i_size_read(&ip->i_inode));
	if (!error)
		error = trunc_end(ip);
	return error;
}

int gfs2_file_dealloc(struct gfs2_inode *ip)
{
	return trunc_dealloc(ip, 0);
}

/**
 * gfs2_free_journal_extents - Free cached journal bmap info
 * @jd: The journal
 *
 */

void gfs2_free_journal_extents(struct gfs2_jdesc *jd)
{
	struct gfs2_journal_extent *jext;

	while(!list_empty(&jd->extent_list)) {
		jext = list_entry(jd->extent_list.next, struct gfs2_journal_extent, list);
		list_del(&jext->list);
		kfree(jext);
	}
}

/**
 * gfs2_add_jextent - Add or merge a new extent to extent cache
 * @jd: The journal descriptor
 * @lblock: The logical block at start of new extent
 * @dblock: The physical block at start of new extent
 * @blocks: Size of extent in fs blocks
 *
 * Returns: 0 on success or -ENOMEM
 */

static int gfs2_add_jextent(struct gfs2_jdesc *jd, u64 lblock, u64 dblock, u64 blocks)
{
	struct gfs2_journal_extent *jext;

	if (!list_empty(&jd->extent_list)) {
		jext = list_entry(jd->extent_list.prev, struct gfs2_journal_extent, list);
		if ((jext->dblock + jext->blocks) == dblock) {
			jext->blocks += blocks;
			return 0;
		}
	}

	jext = kzalloc(sizeof(struct gfs2_journal_extent), GFP_NOFS);
	if (jext == NULL)
		return -ENOMEM;
	jext->dblock = dblock;
	jext->lblock = lblock;
	jext->blocks = blocks;
	list_add_tail(&jext->list, &jd->extent_list);
	jd->nr_extents++;
	return 0;
}

/**
 * gfs2_map_journal_extents - Cache journal bmap info
 * @sdp: The super block
 * @jd: The journal to map
 *
 * Create a reusable "extent" mapping from all logical
 * blocks to all physical blocks for the given journal.  This will save
 * us time when writing journal blocks.  Most journals will have only one
 * extent that maps all their logical blocks.  That's because gfs2.mkfs
 * arranges the journal blocks sequentially to maximize performance.
 * So the extent would map the first block for the entire file length.
 * However, gfs2_jadd can happen while file activity is happening, so
 * those journals may not be sequential.  Less likely is the case where
 * the users created their own journals by mounting the metafs and
 * laying it out.  But it's still possible.  These journals might have
 * several extents.
 *
 * Returns: 0 on success, or error on failure
 */

int gfs2_map_journal_extents(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd)
{
	u64 lblock = 0;
	u64 lblock_stop;
	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
	struct buffer_head bh;
	unsigned int shift = sdp->sd_sb.sb_bsize_shift;
	u64 size;
	int rc;

	lblock_stop = i_size_read(jd->jd_inode) >> shift;
	size = (lblock_stop - lblock) << shift;
	jd->nr_extents = 0;
	WARN_ON(!list_empty(&jd->extent_list));

	do {
		bh.b_state = 0;
		bh.b_blocknr = 0;
		bh.b_size = size;
		rc = gfs2_block_map(jd->jd_inode, lblock, &bh, 0);
		if (rc || !buffer_mapped(&bh))
			goto fail;
		rc = gfs2_add_jextent(jd, lblock, bh.b_blocknr, bh.b_size >> shift);
		if (rc)
			goto fail;
		size -= bh.b_size;
		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
	} while(size > 0);

	fs_info(sdp, "journal %d mapped with %u extents\n", jd->jd_jid,
		jd->nr_extents);
	return 0;

fail:
	fs_warn(sdp, "error %d mapping journal %u at offset %llu (extent %u)\n",
		rc, jd->jd_jid,
		(unsigned long long)(i_size_read(jd->jd_inode) - size),
		jd->nr_extents);
	fs_warn(sdp, "bmap=%d lblock=%llu block=%llu, state=0x%08lx, size=%llu\n",
		rc, (unsigned long long)lblock, (unsigned long long)bh.b_blocknr,
		bh.b_state, (unsigned long long)bh.b_size);
	gfs2_free_journal_extents(jd);
	return rc;
}

/**
 * gfs2_write_alloc_required - figure out if a write will require an allocation
 * @ip: the file being written to
 * @offset: the offset to write to
 * @len: the number of bytes being written
 *
 * Returns: 1 if an alloc is required, 0 otherwise
 */

int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
			      unsigned int len)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head bh;
	unsigned int shift;
	u64 lblock, lblock_stop, size;
	u64 end_of_file;

	if (!len)
		return 0;

	if (gfs2_is_stuffed(ip)) {
		if (offset + len >
		    sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
			return 1;
		return 0;
	}

	shift = sdp->sd_sb.sb_bsize_shift;
	BUG_ON(gfs2_is_dir(ip));
	end_of_file = (i_size_read(&ip->i_inode) + sdp->sd_sb.sb_bsize - 1) >> shift;
	lblock = offset >> shift;
	lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
	if (lblock_stop > end_of_file)
		return 1;

	size = (lblock_stop - lblock) << shift;
	do {
		bh.b_state = 0;
		bh.b_size = size;
		gfs2_block_map(&ip->i_inode, lblock, &bh, 0);
		if (!buffer_mapped(&bh))
			return 1;
		size -= bh.b_size;
		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
	} while(size > 0);

	return 0;
}