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Linux 4.19.133
[linux/fpc-iii.git] / fs / fat / fatent.c
blob4c6c635bc8aaac76c9df5391bb1b0cf58ef8ad6f
1 /*
2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
4 */
5
6 #include <linux/blkdev.h>
7 #include <linux/sched/signal.h>
8 #include "fat.h"
9
10 struct 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
20 static DEFINE_SPINLOCK(fat12_entry_lock);
21
22 static 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);
27 WARN_ON(!fat_valid_entry(sbi, entry));
28 *offset = bytes & (sb->s_blocksize - 1);
29 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
30 }
31
32 static 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);
37 WARN_ON(!fat_valid_entry(sbi, entry));
38 *offset = bytes & (sb->s_blocksize - 1);
39 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
40 }
41
42 static 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
56 static 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
62 static 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
68 static 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);
74 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
75
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
93 err_brelse:
94 brelse(bhs[0]);
95 err:
96 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
97 return -EIO;
98 }
99
100 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
101 int offset, sector_t blocknr)
102 {
103 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
104
105 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
106 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
107 fatent->bhs[0] = sb_bread(sb, blocknr);
108 if (!fatent->bhs[0]) {
109 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
110 (llu)blocknr);
111 return -EIO;
112 }
113 fatent->nr_bhs = 1;
114 ops->ent_set_ptr(fatent, offset);
115 return 0;
116 }
117
118 static int fat12_ent_get(struct fat_entry *fatent)
119 {
120 u8 **ent12_p = fatent->u.ent12_p;
121 int next;
122
123 spin_lock(&fat12_entry_lock);
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];
128 spin_unlock(&fat12_entry_lock);
129
130 next &= 0x0fff;
131 if (next >= BAD_FAT12)
132 next = FAT_ENT_EOF;
133 return next;
134 }
135
136 static 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
145 static 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
154 static 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
161 spin_lock(&fat12_entry_lock);
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 }
169 spin_unlock(&fat12_entry_lock);
170
171 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
172 if (fatent->nr_bhs == 2)
173 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode);
174 }
175
176 static 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);
182 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
183 }
184
185 static void fat32_ent_put(struct fat_entry *fatent, int new)
186 {
187 WARN_ON(new & 0xf0000000);
188 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
189 *fatent->u.ent32_p = cpu_to_le32(new);
190 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
191 }
192
193 static 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) {
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)));
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 {
211 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data +
212 (bhs[0]->b_size - 1)));
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
226 static 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
238 static 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
250 static const struct fatent_operations fat12_ops = {
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
259 static const struct fatent_operations fat16_ops = {
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
268 static const struct fatent_operations fat32_ops = {
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
277 static inline void lock_fat(struct msdos_sb_info *sbi)
278 {
279 mutex_lock(&sbi->fat_lock);
280 }
281
282 static inline void unlock_fat(struct msdos_sb_info *sbi)
283 {
284 mutex_unlock(&sbi->fat_lock);
285 }
286
287 void fat_ent_access_init(struct super_block *sb)
288 {
289 struct msdos_sb_info *sbi = MSDOS_SB(sb);
290
291 mutex_init(&sbi->fat_lock);
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
309 static void mark_fsinfo_dirty(struct super_block *sb)
310 {
311 struct msdos_sb_info *sbi = MSDOS_SB(sb);
312
313 if (sb_rdonly(sb) || sbi->fat_bits != 32)
314 return;
315
316 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
317 }
318
319 static 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);
324 const struct fatent_operations *ops = sbi->fatent_ops;
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;
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 }
344 }
345 ops->ent_set_ptr(fatent, offset);
346 return 1;
347 }
348
349 int 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);
353 const struct fatent_operations *ops = sbi->fatent_ops;
354 int err, offset;
355 sector_t blocknr;
356
357 if (!fat_valid_entry(sbi, entry)) {
358 fatent_brelse(fatent);
359 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
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. */
376 static 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 /* Avoid race with userspace read via bdev */
394 lock_buffer(c_bh);
395 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
396 set_buffer_uptodate(c_bh);
397 unlock_buffer(c_bh);
398 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
399 if (sb->s_flags & SB_SYNCHRONOUS)
400 err = sync_dirty_buffer(c_bh);
401 brelse(c_bh);
402 if (err)
403 goto error;
404 }
405 }
406 error:
407 return err;
408 }
409
410 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
411 int new, int wait)
412 {
413 struct super_block *sb = inode->i_sb;
414 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
415 int err;
416
417 ops->ent_put(fatent, new);
418 if (wait) {
419 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
420 if (err)
421 return err;
422 }
423 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
424 }
425
426 static inline int fat_ent_next(struct msdos_sb_info *sbi,
427 struct fat_entry *fatent)
428 {
429 if (sbi->fatent_ops->ent_next(fatent)) {
430 if (fatent->entry < sbi->max_cluster)
431 return 1;
432 }
433 return 0;
434 }
435
436 static inline int fat_ent_read_block(struct super_block *sb,
437 struct fat_entry *fatent)
438 {
439 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
440 sector_t blocknr;
441 int offset;
442
443 fatent_brelse(fatent);
444 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
445 return ops->ent_bread(sb, fatent, offset, blocknr);
446 }
447
448 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
449 struct fat_entry *fatent)
450 {
451 int n, i;
452
453 for (n = 0; n < fatent->nr_bhs; n++) {
454 for (i = 0; i < *nr_bhs; i++) {
455 if (fatent->bhs[n] == bhs[i])
456 break;
457 }
458 if (i == *nr_bhs) {
459 get_bh(fatent->bhs[n]);
460 bhs[i] = fatent->bhs[n];
461 (*nr_bhs)++;
462 }
463 }
464 }
465
466 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
467 {
468 struct super_block *sb = inode->i_sb;
469 struct msdos_sb_info *sbi = MSDOS_SB(sb);
470 const struct fatent_operations *ops = sbi->fatent_ops;
471 struct fat_entry fatent, prev_ent;
472 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
473 int i, count, err, nr_bhs, idx_clus;
474
475 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
476
477 lock_fat(sbi);
478 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
479 sbi->free_clusters < nr_cluster) {
480 unlock_fat(sbi);
481 return -ENOSPC;
482 }
483
484 err = nr_bhs = idx_clus = 0;
485 count = FAT_START_ENT;
486 fatent_init(&prev_ent);
487 fatent_init(&fatent);
488 fatent_set_entry(&fatent, sbi->prev_free + 1);
489 while (count < sbi->max_cluster) {
490 if (fatent.entry >= sbi->max_cluster)
491 fatent.entry = FAT_START_ENT;
492 fatent_set_entry(&fatent, fatent.entry);
493 err = fat_ent_read_block(sb, &fatent);
494 if (err)
495 goto out;
496
497 /* Find the free entries in a block */
498 do {
499 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
500 int entry = fatent.entry;
501
502 /* make the cluster chain */
503 ops->ent_put(&fatent, FAT_ENT_EOF);
504 if (prev_ent.nr_bhs)
505 ops->ent_put(&prev_ent, entry);
506
507 fat_collect_bhs(bhs, &nr_bhs, &fatent);
508
509 sbi->prev_free = entry;
510 if (sbi->free_clusters != -1)
511 sbi->free_clusters--;
512
513 cluster[idx_clus] = entry;
514 idx_clus++;
515 if (idx_clus == nr_cluster)
516 goto out;
517
518 /*
519 * fat_collect_bhs() gets ref-count of bhs,
520 * so we can still use the prev_ent.
521 */
522 prev_ent = fatent;
523 }
524 count++;
525 if (count == sbi->max_cluster)
526 break;
527 } while (fat_ent_next(sbi, &fatent));
528 }
529
530 /* Couldn't allocate the free entries */
531 sbi->free_clusters = 0;
532 sbi->free_clus_valid = 1;
533 err = -ENOSPC;
534
535 out:
536 unlock_fat(sbi);
537 mark_fsinfo_dirty(sb);
538 fatent_brelse(&fatent);
539 if (!err) {
540 if (inode_needs_sync(inode))
541 err = fat_sync_bhs(bhs, nr_bhs);
542 if (!err)
543 err = fat_mirror_bhs(sb, bhs, nr_bhs);
544 }
545 for (i = 0; i < nr_bhs; i++)
546 brelse(bhs[i]);
547
548 if (err && idx_clus)
549 fat_free_clusters(inode, cluster[0]);
550
551 return err;
552 }
553
554 int fat_free_clusters(struct inode *inode, int cluster)
555 {
556 struct super_block *sb = inode->i_sb;
557 struct msdos_sb_info *sbi = MSDOS_SB(sb);
558 const struct fatent_operations *ops = sbi->fatent_ops;
559 struct fat_entry fatent;
560 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
561 int i, err, nr_bhs;
562 int first_cl = cluster, dirty_fsinfo = 0;
563
564 nr_bhs = 0;
565 fatent_init(&fatent);
566 lock_fat(sbi);
567 do {
568 cluster = fat_ent_read(inode, &fatent, cluster);
569 if (cluster < 0) {
570 err = cluster;
571 goto error;
572 } else if (cluster == FAT_ENT_FREE) {
573 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
574 __func__);
575 err = -EIO;
576 goto error;
577 }
578
579 if (sbi->options.discard) {
580 /*
581 * Issue discard for the sectors we no longer
582 * care about, batching contiguous clusters
583 * into one request
584 */
585 if (cluster != fatent.entry + 1) {
586 int nr_clus = fatent.entry - first_cl + 1;
587
588 sb_issue_discard(sb,
589 fat_clus_to_blknr(sbi, first_cl),
590 nr_clus * sbi->sec_per_clus,
591 GFP_NOFS, 0);
592
593 first_cl = cluster;
594 }
595 }
596
597 ops->ent_put(&fatent, FAT_ENT_FREE);
598 if (sbi->free_clusters != -1) {
599 sbi->free_clusters++;
600 dirty_fsinfo = 1;
601 }
602
603 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
604 if (sb->s_flags & SB_SYNCHRONOUS) {
605 err = fat_sync_bhs(bhs, nr_bhs);
606 if (err)
607 goto error;
608 }
609 err = fat_mirror_bhs(sb, bhs, nr_bhs);
610 if (err)
611 goto error;
612 for (i = 0; i < nr_bhs; i++)
613 brelse(bhs[i]);
614 nr_bhs = 0;
615 }
616 fat_collect_bhs(bhs, &nr_bhs, &fatent);
617 } while (cluster != FAT_ENT_EOF);
618
619 if (sb->s_flags & SB_SYNCHRONOUS) {
620 err = fat_sync_bhs(bhs, nr_bhs);
621 if (err)
622 goto error;
623 }
624 err = fat_mirror_bhs(sb, bhs, nr_bhs);
625 error:
626 fatent_brelse(&fatent);
627 for (i = 0; i < nr_bhs; i++)
628 brelse(bhs[i]);
629 unlock_fat(sbi);
630 if (dirty_fsinfo)
631 mark_fsinfo_dirty(sb);
632
633 return err;
634 }
635 EXPORT_SYMBOL_GPL(fat_free_clusters);
636
637 /* 128kb is the whole sectors for FAT12 and FAT16 */
638 #define FAT_READA_SIZE (128 * 1024)
639
640 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
641 unsigned long reada_blocks)
642 {
643 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
644 sector_t blocknr;
645 int i, offset;
646
647 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
648
649 for (i = 0; i < reada_blocks; i++)
650 sb_breadahead(sb, blocknr + i);
651 }
652
653 int fat_count_free_clusters(struct super_block *sb)
654 {
655 struct msdos_sb_info *sbi = MSDOS_SB(sb);
656 const struct fatent_operations *ops = sbi->fatent_ops;
657 struct fat_entry fatent;
658 unsigned long reada_blocks, reada_mask, cur_block;
659 int err = 0, free;
660
661 lock_fat(sbi);
662 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
663 goto out;
664
665 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
666 reada_mask = reada_blocks - 1;
667 cur_block = 0;
668
669 free = 0;
670 fatent_init(&fatent);
671 fatent_set_entry(&fatent, FAT_START_ENT);
672 while (fatent.entry < sbi->max_cluster) {
673 /* readahead of fat blocks */
674 if ((cur_block & reada_mask) == 0) {
675 unsigned long rest = sbi->fat_length - cur_block;
676 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
677 }
678 cur_block++;
679
680 err = fat_ent_read_block(sb, &fatent);
681 if (err)
682 goto out;
683
684 do {
685 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
686 free++;
687 } while (fat_ent_next(sbi, &fatent));
688 cond_resched();
689 }
690 sbi->free_clusters = free;
691 sbi->free_clus_valid = 1;
692 mark_fsinfo_dirty(sb);
693 fatent_brelse(&fatent);
694 out:
695 unlock_fat(sbi);
696 return err;
697 }
698
699 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
700 {
701 struct msdos_sb_info *sbi = MSDOS_SB(sb);
702 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
703 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
704 }
705
706 int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
707 {
708 struct super_block *sb = inode->i_sb;
709 struct msdos_sb_info *sbi = MSDOS_SB(sb);
710 const struct fatent_operations *ops = sbi->fatent_ops;
711 struct fat_entry fatent;
712 u64 ent_start, ent_end, minlen, trimmed = 0;
713 u32 free = 0;
714 unsigned long reada_blocks, reada_mask, cur_block = 0;
715 int err = 0;
716
717 /*
718 * FAT data is organized as clusters, trim at the granulary of cluster.
719 *
720 * fstrim_range is in byte, convert vaules to cluster index.
721 * Treat sectors before data region as all used, not to trim them.
722 */
723 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
724 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
725 minlen = range->minlen >> sbi->cluster_bits;
726
727 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
728 return -EINVAL;
729 if (ent_end >= sbi->max_cluster)
730 ent_end = sbi->max_cluster - 1;
731
732 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
733 reada_mask = reada_blocks - 1;
734
735 fatent_init(&fatent);
736 lock_fat(sbi);
737 fatent_set_entry(&fatent, ent_start);
738 while (fatent.entry <= ent_end) {
739 /* readahead of fat blocks */
740 if ((cur_block & reada_mask) == 0) {
741 unsigned long rest = sbi->fat_length - cur_block;
742 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
743 }
744 cur_block++;
745
746 err = fat_ent_read_block(sb, &fatent);
747 if (err)
748 goto error;
749 do {
750 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
751 free++;
752 } else if (free) {
753 if (free >= minlen) {
754 u32 clus = fatent.entry - free;
755
756 err = fat_trim_clusters(sb, clus, free);
757 if (err && err != -EOPNOTSUPP)
758 goto error;
759 if (!err)
760 trimmed += free;
761 err = 0;
762 }
763 free = 0;
764 }
765 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
766
767 if (fatal_signal_pending(current)) {
768 err = -ERESTARTSYS;
769 goto error;
770 }
771
772 if (need_resched()) {
773 fatent_brelse(&fatent);
774 unlock_fat(sbi);
775 cond_resched();
776 lock_fat(sbi);
777 }
778 }
779 /* handle scenario when tail entries are all free */
780 if (free && free >= minlen) {
781 u32 clus = fatent.entry - free;
782
783 err = fat_trim_clusters(sb, clus, free);
784 if (err && err != -EOPNOTSUPP)
785 goto error;
786 if (!err)
787 trimmed += free;
788 err = 0;
789 }
790
791 error:
792 fatent_brelse(&fatent);
793 unlock_fat(sbi);
794
795 range->len = trimmed << sbi->cluster_bits;
796
797 return err;
798 }
Linux with added FPC-III support