projects / linux-2.6-block.git / blame
? search:
summary | shortlog | log | commit | commitdiff | tree
blob | blame (incremental) | history | HEAD
Merge branch 'work.alpha' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
[linux-2.6-block.git] / fs / fat / fatent.c
CommitLineData
1da177e4
LT		 1/*
2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
4 */
5
8c540a96 6#include <linux/blkdev.h>
f663b5b3 7#include <linux/sched/signal.h>
9e975dae 8#include "fat.h"
1da177e4
LT		 9
10struct fatent_operations {
11 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
12 void (*ent_set_ptr)(struct fat_entry *, int);
13 int (*ent_bread)(struct super_block *, struct fat_entry *,
14 int, sector_t);
15 int (*ent_get)(struct fat_entry *);
16 void (*ent_put)(struct fat_entry *, int);
17 int (*ent_next)(struct fat_entry *);
18};
19
98283bb4
OH		 20static DEFINE_SPINLOCK(fat12_entry_lock);
21
1da177e4
LT		 22static void fat12_ent_blocknr(struct super_block *sb, int entry,
23 int *offset, sector_t *blocknr)
24{
25 struct msdos_sb_info *sbi = MSDOS_SB(sb);
26 int bytes = entry + (entry >> 1);
0afa9626 27 WARN_ON(!fat_valid_entry(sbi, entry));
1da177e4
LT		 28 *offset = bytes & (sb->s_blocksize - 1);
29 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
30}
31
32static void fat_ent_blocknr(struct super_block *sb, int entry,
33 int *offset, sector_t *blocknr)
34{
35 struct msdos_sb_info *sbi = MSDOS_SB(sb);
36 int bytes = (entry << sbi->fatent_shift);
0afa9626 37 WARN_ON(!fat_valid_entry(sbi, entry));
1da177e4
LT		 38 *offset = bytes & (sb->s_blocksize - 1);
39 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
40}
41
42static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
43{
44 struct buffer_head **bhs = fatent->bhs;
45 if (fatent->nr_bhs == 1) {
46 WARN_ON(offset >= (bhs[0]->b_size - 1));
47 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
48 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
49 } else {
50 WARN_ON(offset != (bhs[0]->b_size - 1));
51 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
52 fatent->u.ent12_p[1] = bhs[1]->b_data;
53 }
54}
55
56static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
57{
58 WARN_ON(offset & (2 - 1));
59 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
60}
61
62static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
63{
64 WARN_ON(offset & (4 - 1));
65 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
66}
67
68static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
69 int offset, sector_t blocknr)
70{
71 struct buffer_head **bhs = fatent->bhs;
72
73 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
b522412a
AV		 74 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
75
1da177e4
LT		 76 bhs[0] = sb_bread(sb, blocknr);
77 if (!bhs[0])
78 goto err;
79
80 if ((offset + 1) < sb->s_blocksize)
81 fatent->nr_bhs = 1;
82 else {
83 /* This entry is block boundary, it needs the next block */
84 blocknr++;
85 bhs[1] = sb_bread(sb, blocknr);
86 if (!bhs[1])
87 goto err_brelse;
88 fatent->nr_bhs = 2;
89 }
90 fat12_ent_set_ptr(fatent, offset);
91 return 0;
92
93err_brelse:
94 brelse(bhs[0]);
95err:
869f58c0 96 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
1da177e4
LT		 97 return -EIO;
98}
99
100static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
101 int offset, sector_t blocknr)
102{
8992de4c 103 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
1da177e4
LT		 104
105 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
b522412a 106 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
1da177e4
LT		 107 fatent->bhs[0] = sb_bread(sb, blocknr);
108 if (!fatent->bhs[0]) {
869f58c0 109 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
c3302931 110 (llu)blocknr);
1da177e4
LT		 111 return -EIO;
112 }
113 fatent->nr_bhs = 1;
114 ops->ent_set_ptr(fatent, offset);
115 return 0;
116}
117
118static int fat12_ent_get(struct fat_entry *fatent)
119{
120 u8 **ent12_p = fatent->u.ent12_p;
121 int next;
122
98283bb4 123 spin_lock(&fat12_entry_lock);
1da177e4
LT		 124 if (fatent->entry & 1)
125 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
126 else
127 next = (*ent12_p[1] << 8) | *ent12_p[0];
98283bb4
OH		 128 spin_unlock(&fat12_entry_lock);
129
1da177e4
LT		 130 next &= 0x0fff;
131 if (next >= BAD_FAT12)
132 next = FAT_ENT_EOF;
133 return next;
134}
135
136static int fat16_ent_get(struct fat_entry *fatent)
137{
138 int next = le16_to_cpu(*fatent->u.ent16_p);
139 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
140 if (next >= BAD_FAT16)
141 next = FAT_ENT_EOF;
142 return next;
143}
144
145static int fat32_ent_get(struct fat_entry *fatent)
146{
147 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
148 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
149 if (next >= BAD_FAT32)
150 next = FAT_ENT_EOF;
151 return next;
152}
153
154static void fat12_ent_put(struct fat_entry *fatent, int new)
155{
156 u8 **ent12_p = fatent->u.ent12_p;
157
158 if (new == FAT_ENT_EOF)
159 new = EOF_FAT12;
160
98283bb4 161 spin_lock(&fat12_entry_lock);
1da177e4
LT		 162 if (fatent->entry & 1) {
163 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
164 *ent12_p[1] = new >> 4;
165 } else {
166 *ent12_p[0] = new & 0xff;
167 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
168 }
98283bb4 169 spin_unlock(&fat12_entry_lock);
1da177e4 170
b522412a 171 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
1da177e4 172 if (fatent->nr_bhs == 2)
b522412a 173 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode);
1da177e4
LT		 174}
175
176static void fat16_ent_put(struct fat_entry *fatent, int new)
177{
178 if (new == FAT_ENT_EOF)
179 new = EOF_FAT16;
180
181 *fatent->u.ent16_p = cpu_to_le16(new);
b522412a 182 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
1da177e4
LT		 183}
184
185static void fat32_ent_put(struct fat_entry *fatent, int new)
186{
1da177e4
LT		 187 WARN_ON(new & 0xf0000000);
188 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
189 *fatent->u.ent32_p = cpu_to_le32(new);
b522412a 190 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
1da177e4
LT		 191}
192
193static int fat12_ent_next(struct fat_entry *fatent)
194{
195 u8 **ent12_p = fatent->u.ent12_p;
196 struct buffer_head **bhs = fatent->bhs;
197 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
198
199 fatent->entry++;
200 if (fatent->nr_bhs == 1) {
441dff34
CJB		 201 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data +
202 (bhs[0]->b_size - 2)));
203 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data +
204 (bhs[0]->b_size - 1)));
1da177e4
LT		 205 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
206 ent12_p[0] = nextp - 1;
207 ent12_p[1] = nextp;
208 return 1;
209 }
210 } else {
441dff34
CJB		 211 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data +
212 (bhs[0]->b_size - 1)));
1da177e4
LT		 213 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
214 ent12_p[0] = nextp - 1;
215 ent12_p[1] = nextp;
216 brelse(bhs[0]);
217 bhs[0] = bhs[1];
218 fatent->nr_bhs = 1;
219 return 1;
220 }
221 ent12_p[0] = NULL;
222 ent12_p[1] = NULL;
223 return 0;
224}
225
226static int fat16_ent_next(struct fat_entry *fatent)
227{
228 const struct buffer_head *bh = fatent->bhs[0];
229 fatent->entry++;
230 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
231 fatent->u.ent16_p++;
232 return 1;
233 }
234 fatent->u.ent16_p = NULL;
235 return 0;
236}
237
238static int fat32_ent_next(struct fat_entry *fatent)
239{
240 const struct buffer_head *bh = fatent->bhs[0];
241 fatent->entry++;
242 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
243 fatent->u.ent32_p++;
244 return 1;
245 }
246 fatent->u.ent32_p = NULL;
247 return 0;
248}
249
8992de4c 250static const struct fatent_operations fat12_ops = {
1da177e4
LT		 251 .ent_blocknr = fat12_ent_blocknr,
252 .ent_set_ptr = fat12_ent_set_ptr,
253 .ent_bread = fat12_ent_bread,
254 .ent_get = fat12_ent_get,
255 .ent_put = fat12_ent_put,
256 .ent_next = fat12_ent_next,
257};
258
8992de4c 259static const struct fatent_operations fat16_ops = {
1da177e4
LT		 260 .ent_blocknr = fat_ent_blocknr,
261 .ent_set_ptr = fat16_ent_set_ptr,
262 .ent_bread = fat_ent_bread,
263 .ent_get = fat16_ent_get,
264 .ent_put = fat16_ent_put,
265 .ent_next = fat16_ent_next,
266};
267
8992de4c 268static const struct fatent_operations fat32_ops = {
1da177e4
LT		 269 .ent_blocknr = fat_ent_blocknr,
270 .ent_set_ptr = fat32_ent_set_ptr,
271 .ent_bread = fat_ent_bread,
272 .ent_get = fat32_ent_get,
273 .ent_put = fat32_ent_put,
274 .ent_next = fat32_ent_next,
275};
276
277static inline void lock_fat(struct msdos_sb_info *sbi)
278{
6b9438e1 279 mutex_lock(&sbi->fat_lock);
1da177e4
LT		 280}
281
282static inline void unlock_fat(struct msdos_sb_info *sbi)
283{
6b9438e1 284 mutex_unlock(&sbi->fat_lock);
1da177e4
LT		 285}
286
287void fat_ent_access_init(struct super_block *sb)
288{
289 struct msdos_sb_info *sbi = MSDOS_SB(sb);
290
6b9438e1 291 mutex_init(&sbi->fat_lock);
1da177e4
LT		 292
293 switch (sbi->fat_bits) {
294 case 32:
295 sbi->fatent_shift = 2;
296 sbi->fatent_ops = &fat32_ops;
297 break;
298 case 16:
299 sbi->fatent_shift = 1;
300 sbi->fatent_ops = &fat16_ops;
301 break;
302 case 12:
303 sbi->fatent_shift = -1;
304 sbi->fatent_ops = &fat12_ops;
305 break;
306 }
307}
308
90b43665
AB		 309static void mark_fsinfo_dirty(struct super_block *sb)
310{
78491189
AB		 311 struct msdos_sb_info *sbi = MSDOS_SB(sb);
312
bc98a42c 313 if (sb_rdonly(sb) || sbi->fat_bits != 32)
78491189
AB		 314 return;
315
316 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
90b43665
AB		 317}
318
1da177e4
LT		 319static inline int fat_ent_update_ptr(struct super_block *sb,
320 struct fat_entry *fatent,
321 int offset, sector_t blocknr)
322{
323 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 324 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 325 struct buffer_head **bhs = fatent->bhs;
326
327 /* Is this fatent's blocks including this entry? */
328 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
329 return 0;
5e35dd46
OH		 330 if (sbi->fat_bits == 12) {
331 if ((offset + 1) < sb->s_blocksize) {
332 /* This entry is on bhs[0]. */
333 if (fatent->nr_bhs == 2) {
334 brelse(bhs[1]);
335 fatent->nr_bhs = 1;
336 }
337 } else {
338 /* This entry needs the next block. */
339 if (fatent->nr_bhs != 2)
340 return 0;
341 if (bhs[1]->b_blocknr != (blocknr + 1))
342 return 0;
343 }
1da177e4
LT		 344 }
345 ops->ent_set_ptr(fatent, offset);
346 return 1;
347}
348
349int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
350{
351 struct super_block *sb = inode->i_sb;
352 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
8992de4c 353 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 354 int err, offset;
355 sector_t blocknr;
356
0afa9626 357 if (!fat_valid_entry(sbi, entry)) {
1da177e4 358 fatent_brelse(fatent);
85c78591 359 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
1da177e4
LT		 360 return -EIO;
361 }
362
363 fatent_set_entry(fatent, entry);
364 ops->ent_blocknr(sb, entry, &offset, &blocknr);
365
366 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
367 fatent_brelse(fatent);
368 err = ops->ent_bread(sb, fatent, offset, blocknr);
369 if (err)
370 return err;
371 }
372 return ops->ent_get(fatent);
373}
374
375/* FIXME: We can write the blocks as more big chunk. */
376static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
377 int nr_bhs)
378{
379 struct msdos_sb_info *sbi = MSDOS_SB(sb);
380 struct buffer_head *c_bh;
381 int err, n, copy;
382
383 err = 0;
384 for (copy = 1; copy < sbi->fats; copy++) {
385 sector_t backup_fat = sbi->fat_length * copy;
386
387 for (n = 0; n < nr_bhs; n++) {
388 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
389 if (!c_bh) {
390 err = -ENOMEM;
391 goto error;
392 }
393 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
394 set_buffer_uptodate(c_bh);
b522412a 395 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
1751e8a6 396 if (sb->s_flags & SB_SYNCHRONOUS)
1da177e4
LT		 397 err = sync_dirty_buffer(c_bh);
398 brelse(c_bh);
399 if (err)
400 goto error;
401 }
402 }
403error:
404 return err;
405}
406
407int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
408 int new, int wait)
409{
410 struct super_block *sb = inode->i_sb;
8992de4c 411 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
1da177e4
LT		 412 int err;
413
414 ops->ent_put(fatent, new);
415 if (wait) {
416 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
417 if (err)
418 return err;
419 }
420 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
421}
422
423static inline int fat_ent_next(struct msdos_sb_info *sbi,
424 struct fat_entry *fatent)
425{
426 if (sbi->fatent_ops->ent_next(fatent)) {
427 if (fatent->entry < sbi->max_cluster)
428 return 1;
429 }
430 return 0;
431}
432
433static inline int fat_ent_read_block(struct super_block *sb,
434 struct fat_entry *fatent)
435{
8992de4c 436 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
1da177e4
LT		 437 sector_t blocknr;
438 int offset;
439
440 fatent_brelse(fatent);
441 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
442 return ops->ent_bread(sb, fatent, offset, blocknr);
443}
444
445static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
446 struct fat_entry *fatent)
447{
448 int n, i;
449
450 for (n = 0; n < fatent->nr_bhs; n++) {
451 for (i = 0; i < *nr_bhs; i++) {
452 if (fatent->bhs[n] == bhs[i])
453 break;
454 }
455 if (i == *nr_bhs) {
456 get_bh(fatent->bhs[n]);
457 bhs[i] = fatent->bhs[n];
458 (*nr_bhs)++;
459 }
460 }
461}
462
463int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
464{
465 struct super_block *sb = inode->i_sb;
466 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 467 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 468 struct fat_entry fatent, prev_ent;
469 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
470 int i, count, err, nr_bhs, idx_clus;
471
472 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
473
474 lock_fat(sbi);
606e423e
OH		 475 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
476 sbi->free_clusters < nr_cluster) {
1da177e4
LT		 477 unlock_fat(sbi);
478 return -ENOSPC;
479 }
480
481 err = nr_bhs = idx_clus = 0;
482 count = FAT_START_ENT;
483 fatent_init(&prev_ent);
484 fatent_init(&fatent);
485 fatent_set_entry(&fatent, sbi->prev_free + 1);
486 while (count < sbi->max_cluster) {
487 if (fatent.entry >= sbi->max_cluster)
488 fatent.entry = FAT_START_ENT;
489 fatent_set_entry(&fatent, fatent.entry);
490 err = fat_ent_read_block(sb, &fatent);
491 if (err)
492 goto out;
493
494 /* Find the free entries in a block */
495 do {
496 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
497 int entry = fatent.entry;
498
499 /* make the cluster chain */
500 ops->ent_put(&fatent, FAT_ENT_EOF);
501 if (prev_ent.nr_bhs)
502 ops->ent_put(&prev_ent, entry);
503
504 fat_collect_bhs(bhs, &nr_bhs, &fatent);
505
506 sbi->prev_free = entry;
507 if (sbi->free_clusters != -1)
508 sbi->free_clusters--;
509
510 cluster[idx_clus] = entry;
511 idx_clus++;
512 if (idx_clus == nr_cluster)
513 goto out;
514
515 /*
516 * fat_collect_bhs() gets ref-count of bhs,
517 * so we can still use the prev_ent.
518 */
519 prev_ent = fatent;
520 }
521 count++;
522 if (count == sbi->max_cluster)
523 break;
524 } while (fat_ent_next(sbi, &fatent));
525 }
526
527 /* Couldn't allocate the free entries */
528 sbi->free_clusters = 0;
606e423e 529 sbi->free_clus_valid = 1;
1da177e4
LT		 530 err = -ENOSPC;
531
532out:
533 unlock_fat(sbi);
330fe3c4 534 mark_fsinfo_dirty(sb);
1da177e4
LT		 535 fatent_brelse(&fatent);
536 if (!err) {
537 if (inode_needs_sync(inode))
538 err = fat_sync_bhs(bhs, nr_bhs);
539 if (!err)
540 err = fat_mirror_bhs(sb, bhs, nr_bhs);
541 }
542 for (i = 0; i < nr_bhs; i++)
543 brelse(bhs[i]);
1da177e4
LT		 544
545 if (err && idx_clus)
546 fat_free_clusters(inode, cluster[0]);
547
548 return err;
549}
550
551int fat_free_clusters(struct inode *inode, int cluster)
552{
553 struct super_block *sb = inode->i_sb;
554 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 555 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 556 struct fat_entry fatent;
557 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
558 int i, err, nr_bhs;
330fe3c4 559 int first_cl = cluster, dirty_fsinfo = 0;
1da177e4
LT		 560
561 nr_bhs = 0;
562 fatent_init(&fatent);
563 lock_fat(sbi);
564 do {
565 cluster = fat_ent_read(inode, &fatent, cluster);
566 if (cluster < 0) {
567 err = cluster;
568 goto error;
569 } else if (cluster == FAT_ENT_FREE) {
85c78591 570 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
8e24eea7 571 __func__);
1da177e4
LT		 572 err = -EIO;
573 goto error;
574 }
575
681142f9
CH		 576 if (sbi->options.discard) {
577 /*
578 * Issue discard for the sectors we no longer
579 * care about, batching contiguous clusters
580 * into one request
581 */
582 if (cluster != fatent.entry + 1) {
583 int nr_clus = fatent.entry - first_cl + 1;
584
585 sb_issue_discard(sb,
586 fat_clus_to_blknr(sbi, first_cl),
2cf6d26a 587 nr_clus * sbi->sec_per_clus,
dd3932ed 588 GFP_NOFS, 0);
681142f9
CH		 589
590 first_cl = cluster;
591 }
8c540a96
DW		 592 }
593
1da177e4 594 ops->ent_put(&fatent, FAT_ENT_FREE);
a6bf6b21 595 if (sbi->free_clusters != -1) {
1da177e4 596 sbi->free_clusters++;
330fe3c4 597 dirty_fsinfo = 1;
a6bf6b21 598 }
1da177e4
LT		 599
600 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
1751e8a6 601 if (sb->s_flags & SB_SYNCHRONOUS) {
1da177e4
LT		 602 err = fat_sync_bhs(bhs, nr_bhs);
603 if (err)
604 goto error;
605 }
606 err = fat_mirror_bhs(sb, bhs, nr_bhs);
607 if (err)
608 goto error;
609 for (i = 0; i < nr_bhs; i++)
610 brelse(bhs[i]);
611 nr_bhs = 0;
612 }
613 fat_collect_bhs(bhs, &nr_bhs, &fatent);
614 } while (cluster != FAT_ENT_EOF);
615
1751e8a6 616 if (sb->s_flags & SB_SYNCHRONOUS) {
1da177e4
LT		 617 err = fat_sync_bhs(bhs, nr_bhs);
618 if (err)
619 goto error;
620 }
621 err = fat_mirror_bhs(sb, bhs, nr_bhs);
622error:
623 fatent_brelse(&fatent);
624 for (i = 0; i < nr_bhs; i++)
625 brelse(bhs[i]);
626 unlock_fat(sbi);
330fe3c4
AB		 627 if (dirty_fsinfo)
628 mark_fsinfo_dirty(sb);
1da177e4 629
1da177e4
LT		 630 return err;
631}
7c709d00 632EXPORT_SYMBOL_GPL(fat_free_clusters);
1da177e4 633
9f966be8
OH		 634/* 128kb is the whole sectors for FAT12 and FAT16 */
635#define FAT_READA_SIZE (128 * 1024)
636
637static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
638 unsigned long reada_blocks)
639{
8992de4c 640 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
9f966be8
OH		 641 sector_t blocknr;
642 int i, offset;
643
644 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
645
646 for (i = 0; i < reada_blocks; i++)
647 sb_breadahead(sb, blocknr + i);
648}
649
1da177e4
LT		 650int fat_count_free_clusters(struct super_block *sb)
651{
652 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 653 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4 654 struct fat_entry fatent;
9f966be8 655 unsigned long reada_blocks, reada_mask, cur_block;
1da177e4
LT		 656 int err = 0, free;
657
658 lock_fat(sbi);
606e423e 659 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
1da177e4
LT		 660 goto out;
661
9f966be8
OH		 662 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
663 reada_mask = reada_blocks - 1;
664 cur_block = 0;
665
1da177e4
LT		 666 free = 0;
667 fatent_init(&fatent);
668 fatent_set_entry(&fatent, FAT_START_ENT);
669 while (fatent.entry < sbi->max_cluster) {
9f966be8
OH		 670 /* readahead of fat blocks */
671 if ((cur_block & reada_mask) == 0) {
672 unsigned long rest = sbi->fat_length - cur_block;
673 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
674 }
675 cur_block++;
676
1da177e4
LT		 677 err = fat_ent_read_block(sb, &fatent);
678 if (err)
679 goto out;
680
681 do {
682 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
683 free++;
684 } while (fat_ent_next(sbi, &fatent));
ac081c3b 685 cond_resched();
1da177e4
LT		 686 }
687 sbi->free_clusters = free;
606e423e 688 sbi->free_clus_valid = 1;
90b43665 689 mark_fsinfo_dirty(sb);
1da177e4
LT		 690 fatent_brelse(&fatent);
691out:
692 unlock_fat(sbi);
693 return err;
694}
f663b5b3
WW		 695
696static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
697{
698 struct msdos_sb_info *sbi = MSDOS_SB(sb);
699 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
700 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
701}
702
703int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
704{
705 struct super_block *sb = inode->i_sb;
706 struct msdos_sb_info *sbi = MSDOS_SB(sb);
707 const struct fatent_operations *ops = sbi->fatent_ops;
708 struct fat_entry fatent;
709 u64 ent_start, ent_end, minlen, trimmed = 0;
710 u32 free = 0;
711 unsigned long reada_blocks, reada_mask, cur_block = 0;
712 int err = 0;
713
714 /*
715 * FAT data is organized as clusters, trim at the granulary of cluster.
716 *
717 * fstrim_range is in byte, convert vaules to cluster index.
718 * Treat sectors before data region as all used, not to trim them.
719 */
720 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
721 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
722 minlen = range->minlen >> sbi->cluster_bits;
723
724 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
725 return -EINVAL;
726 if (ent_end >= sbi->max_cluster)
727 ent_end = sbi->max_cluster - 1;
728
729 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
730 reada_mask = reada_blocks - 1;
731
732 fatent_init(&fatent);
733 lock_fat(sbi);
734 fatent_set_entry(&fatent, ent_start);
735 while (fatent.entry <= ent_end) {
736 /* readahead of fat blocks */
737 if ((cur_block & reada_mask) == 0) {
738 unsigned long rest = sbi->fat_length - cur_block;
739 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
740 }
741 cur_block++;
742
743 err = fat_ent_read_block(sb, &fatent);
744 if (err)
745 goto error;
746 do {
747 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
748 free++;
749 } else if (free) {
750 if (free >= minlen) {
751 u32 clus = fatent.entry - free;
752
753 err = fat_trim_clusters(sb, clus, free);
754 if (err && err != -EOPNOTSUPP)
755 goto error;
756 if (!err)
757 trimmed += free;
758 err = 0;
759 }
760 free = 0;
761 }
762 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
763
764 if (fatal_signal_pending(current)) {
765 err = -ERESTARTSYS;
766 goto error;
767 }
768
769 if (need_resched()) {
770 fatent_brelse(&fatent);
771 unlock_fat(sbi);
772 cond_resched();
773 lock_fat(sbi);
774 }
775 }
776 /* handle scenario when tail entries are all free */
777 if (free && free >= minlen) {
778 u32 clus = fatent.entry - free;
779
780 err = fat_trim_clusters(sb, clus, free);
781 if (err && err != -EOPNOTSUPP)
782 goto error;
783 if (!err)
784 trimmed += free;
785 err = 0;
786 }
787
788error:
789 fatent_brelse(&fatent);
790 unlock_fat(sbi);
791
792 range->len = trimmed << sbi->cluster_bits;
793
794 return err;
795}
Linux 6.x block layer and io_uring tree(s)