forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathinode.c
1308 lines (1195 loc) · 37.8 KB
/
inode.c
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
/*
* linux/fs/ext2/inode.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card ([email protected])
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* from
*
* linux/fs/minix/inode.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Goal-directed block allocation by Stephen Tweedie
* ([email protected]), 1993, 1998
* Big-endian to little-endian byte-swapping/bitmaps by
* David S. Miller ([email protected]), 1995
* 64-bit file support on 64-bit platforms by Jakub Jelinek
*
* Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
*/
#include <linux/smp_lock.h>
#include <linux/time.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include "ext2.h"
#include "acl.h"
#include "xip.h"
MODULE_AUTHOR("Remy Card and others");
MODULE_DESCRIPTION("Second Extended Filesystem");
MODULE_LICENSE("GPL");
static int ext2_update_inode(struct inode * inode, int do_sync);
/*
* Test whether an inode is a fast symlink.
*/
static inline int ext2_inode_is_fast_symlink(struct inode *inode)
{
int ea_blocks = EXT2_I(inode)->i_file_acl ?
(inode->i_sb->s_blocksize >> 9) : 0;
return (S_ISLNK(inode->i_mode) &&
inode->i_blocks - ea_blocks == 0);
}
/*
* Called at each iput().
*
* The inode may be "bad" if ext2_read_inode() saw an error from
* ext2_get_inode(), so we need to check that to avoid freeing random disk
* blocks.
*/
void ext2_put_inode(struct inode *inode)
{
if (!is_bad_inode(inode))
ext2_discard_prealloc(inode);
}
/*
* Called at the last iput() if i_nlink is zero.
*/
void ext2_delete_inode (struct inode * inode)
{
truncate_inode_pages(&inode->i_data, 0);
if (is_bad_inode(inode))
goto no_delete;
EXT2_I(inode)->i_dtime = get_seconds();
mark_inode_dirty(inode);
ext2_update_inode(inode, inode_needs_sync(inode));
inode->i_size = 0;
if (inode->i_blocks)
ext2_truncate (inode);
ext2_free_inode (inode);
return;
no_delete:
clear_inode(inode); /* We must guarantee clearing of inode... */
}
void ext2_discard_prealloc (struct inode * inode)
{
#ifdef EXT2_PREALLOCATE
struct ext2_inode_info *ei = EXT2_I(inode);
write_lock(&ei->i_meta_lock);
if (ei->i_prealloc_count) {
unsigned short total = ei->i_prealloc_count;
unsigned long block = ei->i_prealloc_block;
ei->i_prealloc_count = 0;
ei->i_prealloc_block = 0;
write_unlock(&ei->i_meta_lock);
ext2_free_blocks (inode, block, total);
return;
} else
write_unlock(&ei->i_meta_lock);
#endif
}
static int ext2_alloc_block (struct inode * inode, unsigned long goal, int *err)
{
#ifdef EXT2FS_DEBUG
static unsigned long alloc_hits, alloc_attempts;
#endif
unsigned long result;
#ifdef EXT2_PREALLOCATE
struct ext2_inode_info *ei = EXT2_I(inode);
write_lock(&ei->i_meta_lock);
if (ei->i_prealloc_count &&
(goal == ei->i_prealloc_block || goal + 1 == ei->i_prealloc_block))
{
result = ei->i_prealloc_block++;
ei->i_prealloc_count--;
write_unlock(&ei->i_meta_lock);
ext2_debug ("preallocation hit (%lu/%lu).\n",
++alloc_hits, ++alloc_attempts);
} else {
write_unlock(&ei->i_meta_lock);
ext2_discard_prealloc (inode);
ext2_debug ("preallocation miss (%lu/%lu).\n",
alloc_hits, ++alloc_attempts);
if (S_ISREG(inode->i_mode))
result = ext2_new_block (inode, goal,
&ei->i_prealloc_count,
&ei->i_prealloc_block, err);
else
result = ext2_new_block(inode, goal, NULL, NULL, err);
}
#else
result = ext2_new_block (inode, goal, 0, 0, err);
#endif
return result;
}
typedef struct {
__le32 *p;
__le32 key;
struct buffer_head *bh;
} Indirect;
static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
{
p->key = *(p->p = v);
p->bh = bh;
}
static inline int verify_chain(Indirect *from, Indirect *to)
{
while (from <= to && from->key == *from->p)
from++;
return (from > to);
}
/**
* ext2_block_to_path - parse the block number into array of offsets
* @inode: inode in question (we are only interested in its superblock)
* @i_block: block number to be parsed
* @offsets: array to store the offsets in
* @boundary: set this non-zero if the referred-to block is likely to be
* followed (on disk) by an indirect block.
* To store the locations of file's data ext2 uses a data structure common
* for UNIX filesystems - tree of pointers anchored in the inode, with
* data blocks at leaves and indirect blocks in intermediate nodes.
* This function translates the block number into path in that tree -
* return value is the path length and @offsets[n] is the offset of
* pointer to (n+1)th node in the nth one. If @block is out of range
* (negative or too large) warning is printed and zero returned.
*
* Note: function doesn't find node addresses, so no IO is needed. All
* we need to know is the capacity of indirect blocks (taken from the
* inode->i_sb).
*/
/*
* Portability note: the last comparison (check that we fit into triple
* indirect block) is spelled differently, because otherwise on an
* architecture with 32-bit longs and 8Kb pages we might get into trouble
* if our filesystem had 8Kb blocks. We might use long long, but that would
* kill us on x86. Oh, well, at least the sign propagation does not matter -
* i_block would have to be negative in the very beginning, so we would not
* get there at all.
*/
static int ext2_block_to_path(struct inode *inode,
long i_block, int offsets[4], int *boundary)
{
int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
const long direct_blocks = EXT2_NDIR_BLOCKS,
indirect_blocks = ptrs,
double_blocks = (1 << (ptrs_bits * 2));
int n = 0;
int final = 0;
if (i_block < 0) {
ext2_warning (inode->i_sb, "ext2_block_to_path", "block < 0");
} else if (i_block < direct_blocks) {
offsets[n++] = i_block;
final = direct_blocks;
} else if ( (i_block -= direct_blocks) < indirect_blocks) {
offsets[n++] = EXT2_IND_BLOCK;
offsets[n++] = i_block;
final = ptrs;
} else if ((i_block -= indirect_blocks) < double_blocks) {
offsets[n++] = EXT2_DIND_BLOCK;
offsets[n++] = i_block >> ptrs_bits;
offsets[n++] = i_block & (ptrs - 1);
final = ptrs;
} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
offsets[n++] = EXT2_TIND_BLOCK;
offsets[n++] = i_block >> (ptrs_bits * 2);
offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
offsets[n++] = i_block & (ptrs - 1);
final = ptrs;
} else {
ext2_warning (inode->i_sb, "ext2_block_to_path", "block > big");
}
if (boundary)
*boundary = (i_block & (ptrs - 1)) == (final - 1);
return n;
}
/**
* ext2_get_branch - read the chain of indirect blocks leading to data
* @inode: inode in question
* @depth: depth of the chain (1 - direct pointer, etc.)
* @offsets: offsets of pointers in inode/indirect blocks
* @chain: place to store the result
* @err: here we store the error value
*
* Function fills the array of triples <key, p, bh> and returns %NULL
* if everything went OK or the pointer to the last filled triple
* (incomplete one) otherwise. Upon the return chain[i].key contains
* the number of (i+1)-th block in the chain (as it is stored in memory,
* i.e. little-endian 32-bit), chain[i].p contains the address of that
* number (it points into struct inode for i==0 and into the bh->b_data
* for i>0) and chain[i].bh points to the buffer_head of i-th indirect
* block for i>0 and NULL for i==0. In other words, it holds the block
* numbers of the chain, addresses they were taken from (and where we can
* verify that chain did not change) and buffer_heads hosting these
* numbers.
*
* Function stops when it stumbles upon zero pointer (absent block)
* (pointer to last triple returned, *@err == 0)
* or when it gets an IO error reading an indirect block
* (ditto, *@err == -EIO)
* or when it notices that chain had been changed while it was reading
* (ditto, *@err == -EAGAIN)
* or when it reads all @depth-1 indirect blocks successfully and finds
* the whole chain, all way to the data (returns %NULL, *err == 0).
*/
static Indirect *ext2_get_branch(struct inode *inode,
int depth,
int *offsets,
Indirect chain[4],
int *err)
{
struct super_block *sb = inode->i_sb;
Indirect *p = chain;
struct buffer_head *bh;
*err = 0;
/* i_data is not going away, no lock needed */
add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
if (!p->key)
goto no_block;
while (--depth) {
bh = sb_bread(sb, le32_to_cpu(p->key));
if (!bh)
goto failure;
read_lock(&EXT2_I(inode)->i_meta_lock);
if (!verify_chain(chain, p))
goto changed;
add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
read_unlock(&EXT2_I(inode)->i_meta_lock);
if (!p->key)
goto no_block;
}
return NULL;
changed:
read_unlock(&EXT2_I(inode)->i_meta_lock);
brelse(bh);
*err = -EAGAIN;
goto no_block;
failure:
*err = -EIO;
no_block:
return p;
}
/**
* ext2_find_near - find a place for allocation with sufficient locality
* @inode: owner
* @ind: descriptor of indirect block.
*
* This function returns the prefered place for block allocation.
* It is used when heuristic for sequential allocation fails.
* Rules are:
* + if there is a block to the left of our position - allocate near it.
* + if pointer will live in indirect block - allocate near that block.
* + if pointer will live in inode - allocate in the same cylinder group.
*
* In the latter case we colour the starting block by the callers PID to
* prevent it from clashing with concurrent allocations for a different inode
* in the same block group. The PID is used here so that functionally related
* files will be close-by on-disk.
*
* Caller must make sure that @ind is valid and will stay that way.
*/
static unsigned long ext2_find_near(struct inode *inode, Indirect *ind)
{
struct ext2_inode_info *ei = EXT2_I(inode);
__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
__le32 *p;
unsigned long bg_start;
unsigned long colour;
/* Try to find previous block */
for (p = ind->p - 1; p >= start; p--)
if (*p)
return le32_to_cpu(*p);
/* No such thing, so let's try location of indirect block */
if (ind->bh)
return ind->bh->b_blocknr;
/*
* It is going to be refered from inode itself? OK, just put it into
* the same cylinder group then.
*/
bg_start = (ei->i_block_group * EXT2_BLOCKS_PER_GROUP(inode->i_sb)) +
le32_to_cpu(EXT2_SB(inode->i_sb)->s_es->s_first_data_block);
colour = (current->pid % 16) *
(EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
return bg_start + colour;
}
/**
* ext2_find_goal - find a prefered place for allocation.
* @inode: owner
* @block: block we want
* @chain: chain of indirect blocks
* @partial: pointer to the last triple within a chain
* @goal: place to store the result.
*
* Normally this function find the prefered place for block allocation,
* stores it in *@goal and returns zero. If the branch had been changed
* under us we return -EAGAIN.
*/
static inline int ext2_find_goal(struct inode *inode,
long block,
Indirect chain[4],
Indirect *partial,
unsigned long *goal)
{
struct ext2_inode_info *ei = EXT2_I(inode);
write_lock(&ei->i_meta_lock);
if ((block == ei->i_next_alloc_block + 1) && ei->i_next_alloc_goal) {
ei->i_next_alloc_block++;
ei->i_next_alloc_goal++;
}
if (verify_chain(chain, partial)) {
/*
* try the heuristic for sequential allocation,
* failing that at least try to get decent locality.
*/
if (block == ei->i_next_alloc_block)
*goal = ei->i_next_alloc_goal;
if (!*goal)
*goal = ext2_find_near(inode, partial);
write_unlock(&ei->i_meta_lock);
return 0;
}
write_unlock(&ei->i_meta_lock);
return -EAGAIN;
}
/**
* ext2_alloc_branch - allocate and set up a chain of blocks.
* @inode: owner
* @num: depth of the chain (number of blocks to allocate)
* @offsets: offsets (in the blocks) to store the pointers to next.
* @branch: place to store the chain in.
*
* This function allocates @num blocks, zeroes out all but the last one,
* links them into chain and (if we are synchronous) writes them to disk.
* In other words, it prepares a branch that can be spliced onto the
* inode. It stores the information about that chain in the branch[], in
* the same format as ext2_get_branch() would do. We are calling it after
* we had read the existing part of chain and partial points to the last
* triple of that (one with zero ->key). Upon the exit we have the same
* picture as after the successful ext2_get_block(), excpet that in one
* place chain is disconnected - *branch->p is still zero (we did not
* set the last link), but branch->key contains the number that should
* be placed into *branch->p to fill that gap.
*
* If allocation fails we free all blocks we've allocated (and forget
* their buffer_heads) and return the error value the from failed
* ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
* as described above and return 0.
*/
static int ext2_alloc_branch(struct inode *inode,
int num,
unsigned long goal,
int *offsets,
Indirect *branch)
{
int blocksize = inode->i_sb->s_blocksize;
int n = 0;
int err;
int i;
int parent = ext2_alloc_block(inode, goal, &err);
branch[0].key = cpu_to_le32(parent);
if (parent) for (n = 1; n < num; n++) {
struct buffer_head *bh;
/* Allocate the next block */
int nr = ext2_alloc_block(inode, parent, &err);
if (!nr)
break;
branch[n].key = cpu_to_le32(nr);
/*
* Get buffer_head for parent block, zero it out and set
* the pointer to new one, then send parent to disk.
*/
bh = sb_getblk(inode->i_sb, parent);
if (!bh) {
err = -EIO;
break;
}
lock_buffer(bh);
memset(bh->b_data, 0, blocksize);
branch[n].bh = bh;
branch[n].p = (__le32 *) bh->b_data + offsets[n];
*branch[n].p = branch[n].key;
set_buffer_uptodate(bh);
unlock_buffer(bh);
mark_buffer_dirty_inode(bh, inode);
/* We used to sync bh here if IS_SYNC(inode).
* But we now rely upon generic_osync_inode()
* and b_inode_buffers. But not for directories.
*/
if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
sync_dirty_buffer(bh);
parent = nr;
}
if (n == num)
return 0;
/* Allocation failed, free what we already allocated */
for (i = 1; i < n; i++)
bforget(branch[i].bh);
for (i = 0; i < n; i++)
ext2_free_blocks(inode, le32_to_cpu(branch[i].key), 1);
return err;
}
/**
* ext2_splice_branch - splice the allocated branch onto inode.
* @inode: owner
* @block: (logical) number of block we are adding
* @chain: chain of indirect blocks (with a missing link - see
* ext2_alloc_branch)
* @where: location of missing link
* @num: number of blocks we are adding
*
* This function verifies that chain (up to the missing link) had not
* changed, fills the missing link and does all housekeeping needed in
* inode (->i_blocks, etc.). In case of success we end up with the full
* chain to new block and return 0. Otherwise (== chain had been changed)
* we free the new blocks (forgetting their buffer_heads, indeed) and
* return -EAGAIN.
*/
static inline int ext2_splice_branch(struct inode *inode,
long block,
Indirect chain[4],
Indirect *where,
int num)
{
struct ext2_inode_info *ei = EXT2_I(inode);
int i;
/* Verify that place we are splicing to is still there and vacant */
write_lock(&ei->i_meta_lock);
if (!verify_chain(chain, where-1) || *where->p)
goto changed;
/* That's it */
*where->p = where->key;
ei->i_next_alloc_block = block;
ei->i_next_alloc_goal = le32_to_cpu(where[num-1].key);
write_unlock(&ei->i_meta_lock);
/* We are done with atomic stuff, now do the rest of housekeeping */
inode->i_ctime = CURRENT_TIME_SEC;
/* had we spliced it onto indirect block? */
if (where->bh)
mark_buffer_dirty_inode(where->bh, inode);
mark_inode_dirty(inode);
return 0;
changed:
write_unlock(&ei->i_meta_lock);
for (i = 1; i < num; i++)
bforget(where[i].bh);
for (i = 0; i < num; i++)
ext2_free_blocks(inode, le32_to_cpu(where[i].key), 1);
return -EAGAIN;
}
/*
* Allocation strategy is simple: if we have to allocate something, we will
* have to go the whole way to leaf. So let's do it before attaching anything
* to tree, set linkage between the newborn blocks, write them if sync is
* required, recheck the path, free and repeat if check fails, otherwise
* set the last missing link (that will protect us from any truncate-generated
* removals - all blocks on the path are immune now) and possibly force the
* write on the parent block.
* That has a nice additional property: no special recovery from the failed
* allocations is needed - we simply release blocks and do not touch anything
* reachable from inode.
*/
int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
{
int err = -EIO;
int offsets[4];
Indirect chain[4];
Indirect *partial;
unsigned long goal;
int left;
int boundary = 0;
int depth = ext2_block_to_path(inode, iblock, offsets, &boundary);
if (depth == 0)
goto out;
reread:
partial = ext2_get_branch(inode, depth, offsets, chain, &err);
/* Simplest case - block found, no allocation needed */
if (!partial) {
got_it:
map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
if (boundary)
set_buffer_boundary(bh_result);
/* Clean up and exit */
partial = chain+depth-1; /* the whole chain */
goto cleanup;
}
/* Next simple case - plain lookup or failed read of indirect block */
if (!create || err == -EIO) {
cleanup:
while (partial > chain) {
brelse(partial->bh);
partial--;
}
out:
return err;
}
/*
* Indirect block might be removed by truncate while we were
* reading it. Handling of that case (forget what we've got and
* reread) is taken out of the main path.
*/
if (err == -EAGAIN)
goto changed;
goal = 0;
if (ext2_find_goal(inode, iblock, chain, partial, &goal) < 0)
goto changed;
left = (chain + depth) - partial;
err = ext2_alloc_branch(inode, left, goal,
offsets+(partial-chain), partial);
if (err)
goto cleanup;
if (ext2_use_xip(inode->i_sb)) {
/*
* we need to clear the block
*/
err = ext2_clear_xip_target (inode,
le32_to_cpu(chain[depth-1].key));
if (err)
goto cleanup;
}
if (ext2_splice_branch(inode, iblock, chain, partial, left) < 0)
goto changed;
set_buffer_new(bh_result);
goto got_it;
changed:
while (partial > chain) {
brelse(partial->bh);
partial--;
}
goto reread;
}
static int ext2_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, ext2_get_block, wbc);
}
static int ext2_readpage(struct file *file, struct page *page)
{
return mpage_readpage(page, ext2_get_block);
}
static int
ext2_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
}
static int
ext2_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
return block_prepare_write(page,from,to,ext2_get_block);
}
static int
ext2_nobh_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
return nobh_prepare_write(page,from,to,ext2_get_block);
}
static int ext2_nobh_writepage(struct page *page,
struct writeback_control *wbc)
{
return nobh_writepage(page, ext2_get_block, wbc);
}
static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
{
return generic_block_bmap(mapping,block,ext2_get_block);
}
static ssize_t
ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
loff_t offset, unsigned long nr_segs)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
offset, nr_segs, ext2_get_block, NULL);
}
static int
ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
return mpage_writepages(mapping, wbc, ext2_get_block);
}
struct address_space_operations ext2_aops = {
.readpage = ext2_readpage,
.readpages = ext2_readpages,
.writepage = ext2_writepage,
.sync_page = block_sync_page,
.prepare_write = ext2_prepare_write,
.commit_write = generic_commit_write,
.bmap = ext2_bmap,
.direct_IO = ext2_direct_IO,
.writepages = ext2_writepages,
.migratepage = buffer_migrate_page,
};
struct address_space_operations ext2_aops_xip = {
.bmap = ext2_bmap,
.get_xip_page = ext2_get_xip_page,
};
struct address_space_operations ext2_nobh_aops = {
.readpage = ext2_readpage,
.readpages = ext2_readpages,
.writepage = ext2_nobh_writepage,
.sync_page = block_sync_page,
.prepare_write = ext2_nobh_prepare_write,
.commit_write = nobh_commit_write,
.bmap = ext2_bmap,
.direct_IO = ext2_direct_IO,
.writepages = ext2_writepages,
.migratepage = buffer_migrate_page,
};
/*
* Probably it should be a library function... search for first non-zero word
* or memcmp with zero_page, whatever is better for particular architecture.
* Linus?
*/
static inline int all_zeroes(__le32 *p, __le32 *q)
{
while (p < q)
if (*p++)
return 0;
return 1;
}
/**
* ext2_find_shared - find the indirect blocks for partial truncation.
* @inode: inode in question
* @depth: depth of the affected branch
* @offsets: offsets of pointers in that branch (see ext2_block_to_path)
* @chain: place to store the pointers to partial indirect blocks
* @top: place to the (detached) top of branch
*
* This is a helper function used by ext2_truncate().
*
* When we do truncate() we may have to clean the ends of several indirect
* blocks but leave the blocks themselves alive. Block is partially
* truncated if some data below the new i_size is refered from it (and
* it is on the path to the first completely truncated data block, indeed).
* We have to free the top of that path along with everything to the right
* of the path. Since no allocation past the truncation point is possible
* until ext2_truncate() finishes, we may safely do the latter, but top
* of branch may require special attention - pageout below the truncation
* point might try to populate it.
*
* We atomically detach the top of branch from the tree, store the block
* number of its root in *@top, pointers to buffer_heads of partially
* truncated blocks - in @chain[].bh and pointers to their last elements
* that should not be removed - in @chain[].p. Return value is the pointer
* to last filled element of @chain.
*
* The work left to caller to do the actual freeing of subtrees:
* a) free the subtree starting from *@top
* b) free the subtrees whose roots are stored in
* (@chain[i].p+1 .. end of @chain[i].bh->b_data)
* c) free the subtrees growing from the inode past the @chain[0].p
* (no partially truncated stuff there).
*/
static Indirect *ext2_find_shared(struct inode *inode,
int depth,
int offsets[4],
Indirect chain[4],
__le32 *top)
{
Indirect *partial, *p;
int k, err;
*top = 0;
for (k = depth; k > 1 && !offsets[k-1]; k--)
;
partial = ext2_get_branch(inode, k, offsets, chain, &err);
if (!partial)
partial = chain + k-1;
/*
* If the branch acquired continuation since we've looked at it -
* fine, it should all survive and (new) top doesn't belong to us.
*/
write_lock(&EXT2_I(inode)->i_meta_lock);
if (!partial->key && *partial->p) {
write_unlock(&EXT2_I(inode)->i_meta_lock);
goto no_top;
}
for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
;
/*
* OK, we've found the last block that must survive. The rest of our
* branch should be detached before unlocking. However, if that rest
* of branch is all ours and does not grow immediately from the inode
* it's easier to cheat and just decrement partial->p.
*/
if (p == chain + k - 1 && p > chain) {
p->p--;
} else {
*top = *p->p;
*p->p = 0;
}
write_unlock(&EXT2_I(inode)->i_meta_lock);
while(partial > p)
{
brelse(partial->bh);
partial--;
}
no_top:
return partial;
}
/**
* ext2_free_data - free a list of data blocks
* @inode: inode we are dealing with
* @p: array of block numbers
* @q: points immediately past the end of array
*
* We are freeing all blocks refered from that array (numbers are
* stored as little-endian 32-bit) and updating @inode->i_blocks
* appropriately.
*/
static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
{
unsigned long block_to_free = 0, count = 0;
unsigned long nr;
for ( ; p < q ; p++) {
nr = le32_to_cpu(*p);
if (nr) {
*p = 0;
/* accumulate blocks to free if they're contiguous */
if (count == 0)
goto free_this;
else if (block_to_free == nr - count)
count++;
else {
mark_inode_dirty(inode);
ext2_free_blocks (inode, block_to_free, count);
free_this:
block_to_free = nr;
count = 1;
}
}
}
if (count > 0) {
mark_inode_dirty(inode);
ext2_free_blocks (inode, block_to_free, count);
}
}
/**
* ext2_free_branches - free an array of branches
* @inode: inode we are dealing with
* @p: array of block numbers
* @q: pointer immediately past the end of array
* @depth: depth of the branches to free
*
* We are freeing all blocks refered from these branches (numbers are
* stored as little-endian 32-bit) and updating @inode->i_blocks
* appropriately.
*/
static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
{
struct buffer_head * bh;
unsigned long nr;
if (depth--) {
int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
for ( ; p < q ; p++) {
nr = le32_to_cpu(*p);
if (!nr)
continue;
*p = 0;
bh = sb_bread(inode->i_sb, nr);
/*
* A read failure? Report error and clear slot
* (should be rare).
*/
if (!bh) {
ext2_error(inode->i_sb, "ext2_free_branches",
"Read failure, inode=%ld, block=%ld",
inode->i_ino, nr);
continue;
}
ext2_free_branches(inode,
(__le32*)bh->b_data,
(__le32*)bh->b_data + addr_per_block,
depth);
bforget(bh);
ext2_free_blocks(inode, nr, 1);
mark_inode_dirty(inode);
}
} else
ext2_free_data(inode, p, q);
}
void ext2_truncate (struct inode * inode)
{
__le32 *i_data = EXT2_I(inode)->i_data;
int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
int offsets[4];
Indirect chain[4];
Indirect *partial;
__le32 nr = 0;
int n;
long iblock;
unsigned blocksize;
if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
S_ISLNK(inode->i_mode)))
return;
if (ext2_inode_is_fast_symlink(inode))
return;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
return;
ext2_discard_prealloc(inode);
blocksize = inode->i_sb->s_blocksize;
iblock = (inode->i_size + blocksize-1)
>> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
if (mapping_is_xip(inode->i_mapping))
xip_truncate_page(inode->i_mapping, inode->i_size);
else if (test_opt(inode->i_sb, NOBH))
nobh_truncate_page(inode->i_mapping, inode->i_size);
else
block_truncate_page(inode->i_mapping,
inode->i_size, ext2_get_block);
n = ext2_block_to_path(inode, iblock, offsets, NULL);
if (n == 0)
return;
if (n == 1) {
ext2_free_data(inode, i_data+offsets[0],
i_data + EXT2_NDIR_BLOCKS);
goto do_indirects;
}
partial = ext2_find_shared(inode, n, offsets, chain, &nr);
/* Kill the top of shared branch (already detached) */
if (nr) {
if (partial == chain)
mark_inode_dirty(inode);
else
mark_buffer_dirty_inode(partial->bh, inode);
ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
}
/* Clear the ends of indirect blocks on the shared branch */
while (partial > chain) {
ext2_free_branches(inode,
partial->p + 1,
(__le32*)partial->bh->b_data+addr_per_block,
(chain+n-1) - partial);
mark_buffer_dirty_inode(partial->bh, inode);
brelse (partial->bh);
partial--;
}
do_indirects:
/* Kill the remaining (whole) subtrees */
switch (offsets[0]) {
default:
nr = i_data[EXT2_IND_BLOCK];
if (nr) {
i_data[EXT2_IND_BLOCK] = 0;
mark_inode_dirty(inode);
ext2_free_branches(inode, &nr, &nr+1, 1);
}
case EXT2_IND_BLOCK:
nr = i_data[EXT2_DIND_BLOCK];
if (nr) {
i_data[EXT2_DIND_BLOCK] = 0;
mark_inode_dirty(inode);
ext2_free_branches(inode, &nr, &nr+1, 2);
}
case EXT2_DIND_BLOCK:
nr = i_data[EXT2_TIND_BLOCK];
if (nr) {
i_data[EXT2_TIND_BLOCK] = 0;
mark_inode_dirty(inode);
ext2_free_branches(inode, &nr, &nr+1, 3);
}
case EXT2_TIND_BLOCK:
;
}
inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
if (inode_needs_sync(inode)) {
sync_mapping_buffers(inode->i_mapping);
ext2_sync_inode (inode);
} else {
mark_inode_dirty(inode);
}
}
static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
struct buffer_head **p)
{