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Merge tag 'rproc-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/andersson...
[mirror_ubuntu-jammy-kernel.git] / fs / fat / fatent.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2004, OGAWA Hirofumi
4 */
5
6 #include <linux/blkdev.h>
7 #include <linux/sched/signal.h>
8 #include <linux/backing-dev-defs.h>
9 #include "fat.h"
10
11 struct fatent_operations {
12 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
13 void (*ent_set_ptr)(struct fat_entry *, int);
14 int (*ent_bread)(struct super_block *, struct fat_entry *,
15 int, sector_t);
16 int (*ent_get)(struct fat_entry *);
17 void (*ent_put)(struct fat_entry *, int);
18 int (*ent_next)(struct fat_entry *);
19 };
20
21 static DEFINE_SPINLOCK(fat12_entry_lock);
22
23 static void fat12_ent_blocknr(struct super_block *sb, int entry,
24 int *offset, sector_t *blocknr)
25 {
26 struct msdos_sb_info *sbi = MSDOS_SB(sb);
27 int bytes = entry + (entry >> 1);
28 WARN_ON(!fat_valid_entry(sbi, entry));
29 *offset = bytes & (sb->s_blocksize - 1);
30 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
31 }
32
33 static void fat_ent_blocknr(struct super_block *sb, int entry,
34 int *offset, sector_t *blocknr)
35 {
36 struct msdos_sb_info *sbi = MSDOS_SB(sb);
37 int bytes = (entry << sbi->fatent_shift);
38 WARN_ON(!fat_valid_entry(sbi, entry));
39 *offset = bytes & (sb->s_blocksize - 1);
40 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
41 }
42
43 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
44 {
45 struct buffer_head **bhs = fatent->bhs;
46 if (fatent->nr_bhs == 1) {
47 WARN_ON(offset >= (bhs[0]->b_size - 1));
48 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
49 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
50 } else {
51 WARN_ON(offset != (bhs[0]->b_size - 1));
52 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
53 fatent->u.ent12_p[1] = bhs[1]->b_data;
54 }
55 }
56
57 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
58 {
59 WARN_ON(offset & (2 - 1));
60 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
61 }
62
63 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
64 {
65 WARN_ON(offset & (4 - 1));
66 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
67 }
68
69 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
70 int offset, sector_t blocknr)
71 {
72 struct buffer_head **bhs = fatent->bhs;
73
74 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
75 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
76
77 bhs[0] = sb_bread(sb, blocknr);
78 if (!bhs[0])
79 goto err;
80
81 if ((offset + 1) < sb->s_blocksize)
82 fatent->nr_bhs = 1;
83 else {
84 /* This entry is block boundary, it needs the next block */
85 blocknr++;
86 bhs[1] = sb_bread(sb, blocknr);
87 if (!bhs[1])
88 goto err_brelse;
89 fatent->nr_bhs = 2;
90 }
91 fat12_ent_set_ptr(fatent, offset);
92 return 0;
93
94 err_brelse:
95 brelse(bhs[0]);
96 err:
97 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
98 return -EIO;
99 }
100
101 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
102 int offset, sector_t blocknr)
103 {
104 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
105
106 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
107 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
108 fatent->bhs[0] = sb_bread(sb, blocknr);
109 if (!fatent->bhs[0]) {
110 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
111 (llu)blocknr);
112 return -EIO;
113 }
114 fatent->nr_bhs = 1;
115 ops->ent_set_ptr(fatent, offset);
116 return 0;
117 }
118
119 static int fat12_ent_get(struct fat_entry *fatent)
120 {
121 u8 **ent12_p = fatent->u.ent12_p;
122 int next;
123
124 spin_lock(&fat12_entry_lock);
125 if (fatent->entry & 1)
126 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
127 else
128 next = (*ent12_p[1] << 8) | *ent12_p[0];
129 spin_unlock(&fat12_entry_lock);
130
131 next &= 0x0fff;
132 if (next >= BAD_FAT12)
133 next = FAT_ENT_EOF;
134 return next;
135 }
136
137 static int fat16_ent_get(struct fat_entry *fatent)
138 {
139 int next = le16_to_cpu(*fatent->u.ent16_p);
140 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
141 if (next >= BAD_FAT16)
142 next = FAT_ENT_EOF;
143 return next;
144 }
145
146 static int fat32_ent_get(struct fat_entry *fatent)
147 {
148 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
149 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
150 if (next >= BAD_FAT32)
151 next = FAT_ENT_EOF;
152 return next;
153 }
154
155 static void fat12_ent_put(struct fat_entry *fatent, int new)
156 {
157 u8 **ent12_p = fatent->u.ent12_p;
158
159 if (new == FAT_ENT_EOF)
160 new = EOF_FAT12;
161
162 spin_lock(&fat12_entry_lock);
163 if (fatent->entry & 1) {
164 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
165 *ent12_p[1] = new >> 4;
166 } else {
167 *ent12_p[0] = new & 0xff;
168 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
169 }
170 spin_unlock(&fat12_entry_lock);
171
172 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
173 if (fatent->nr_bhs == 2)
174 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode);
175 }
176
177 static void fat16_ent_put(struct fat_entry *fatent, int new)
178 {
179 if (new == FAT_ENT_EOF)
180 new = EOF_FAT16;
181
182 *fatent->u.ent16_p = cpu_to_le16(new);
183 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
184 }
185
186 static void fat32_ent_put(struct fat_entry *fatent, int new)
187 {
188 WARN_ON(new & 0xf0000000);
189 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
190 *fatent->u.ent32_p = cpu_to_le32(new);
191 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
192 }
193
194 static int fat12_ent_next(struct fat_entry *fatent)
195 {
196 u8 **ent12_p = fatent->u.ent12_p;
197 struct buffer_head **bhs = fatent->bhs;
198 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
199
200 fatent->entry++;
201 if (fatent->nr_bhs == 1) {
202 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data +
203 (bhs[0]->b_size - 2)));
204 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data +
205 (bhs[0]->b_size - 1)));
206 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
207 ent12_p[0] = nextp - 1;
208 ent12_p[1] = nextp;
209 return 1;
210 }
211 } else {
212 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data +
213 (bhs[0]->b_size - 1)));
214 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
215 ent12_p[0] = nextp - 1;
216 ent12_p[1] = nextp;
217 brelse(bhs[0]);
218 bhs[0] = bhs[1];
219 fatent->nr_bhs = 1;
220 return 1;
221 }
222 ent12_p[0] = NULL;
223 ent12_p[1] = NULL;
224 return 0;
225 }
226
227 static int fat16_ent_next(struct fat_entry *fatent)
228 {
229 const struct buffer_head *bh = fatent->bhs[0];
230 fatent->entry++;
231 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
232 fatent->u.ent16_p++;
233 return 1;
234 }
235 fatent->u.ent16_p = NULL;
236 return 0;
237 }
238
239 static int fat32_ent_next(struct fat_entry *fatent)
240 {
241 const struct buffer_head *bh = fatent->bhs[0];
242 fatent->entry++;
243 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
244 fatent->u.ent32_p++;
245 return 1;
246 }
247 fatent->u.ent32_p = NULL;
248 return 0;
249 }
250
251 static const struct fatent_operations fat12_ops = {
252 .ent_blocknr = fat12_ent_blocknr,
253 .ent_set_ptr = fat12_ent_set_ptr,
254 .ent_bread = fat12_ent_bread,
255 .ent_get = fat12_ent_get,
256 .ent_put = fat12_ent_put,
257 .ent_next = fat12_ent_next,
258 };
259
260 static const struct fatent_operations fat16_ops = {
261 .ent_blocknr = fat_ent_blocknr,
262 .ent_set_ptr = fat16_ent_set_ptr,
263 .ent_bread = fat_ent_bread,
264 .ent_get = fat16_ent_get,
265 .ent_put = fat16_ent_put,
266 .ent_next = fat16_ent_next,
267 };
268
269 static const struct fatent_operations fat32_ops = {
270 .ent_blocknr = fat_ent_blocknr,
271 .ent_set_ptr = fat32_ent_set_ptr,
272 .ent_bread = fat_ent_bread,
273 .ent_get = fat32_ent_get,
274 .ent_put = fat32_ent_put,
275 .ent_next = fat32_ent_next,
276 };
277
278 static inline void lock_fat(struct msdos_sb_info *sbi)
279 {
280 mutex_lock(&sbi->fat_lock);
281 }
282
283 static inline void unlock_fat(struct msdos_sb_info *sbi)
284 {
285 mutex_unlock(&sbi->fat_lock);
286 }
287
288 void fat_ent_access_init(struct super_block *sb)
289 {
290 struct msdos_sb_info *sbi = MSDOS_SB(sb);
291
292 mutex_init(&sbi->fat_lock);
293
294 if (is_fat32(sbi)) {
295 sbi->fatent_shift = 2;
296 sbi->fatent_ops = &fat32_ops;
297 } else if (is_fat16(sbi)) {
298 sbi->fatent_shift = 1;
299 sbi->fatent_ops = &fat16_ops;
300 } else if (is_fat12(sbi)) {
301 sbi->fatent_shift = -1;
302 sbi->fatent_ops = &fat12_ops;
303 } else {
304 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
305 }
306 }
307
308 static void mark_fsinfo_dirty(struct super_block *sb)
309 {
310 struct msdos_sb_info *sbi = MSDOS_SB(sb);
311
312 if (sb_rdonly(sb) || !is_fat32(sbi))
313 return;
314
315 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
316 }
317
318 static inline int fat_ent_update_ptr(struct super_block *sb,
319 struct fat_entry *fatent,
320 int offset, sector_t blocknr)
321 {
322 struct msdos_sb_info *sbi = MSDOS_SB(sb);
323 const struct fatent_operations *ops = sbi->fatent_ops;
324 struct buffer_head **bhs = fatent->bhs;
325
326 /* Is this fatent's blocks including this entry? */
327 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
328 return 0;
329 if (is_fat12(sbi)) {
330 if ((offset + 1) < sb->s_blocksize) {
331 /* This entry is on bhs[0]. */
332 if (fatent->nr_bhs == 2) {
333 brelse(bhs[1]);
334 fatent->nr_bhs = 1;
335 }
336 } else {
337 /* This entry needs the next block. */
338 if (fatent->nr_bhs != 2)
339 return 0;
340 if (bhs[1]->b_blocknr != (blocknr + 1))
341 return 0;
342 }
343 }
344 ops->ent_set_ptr(fatent, offset);
345 return 1;
346 }
347
348 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
349 {
350 struct super_block *sb = inode->i_sb;
351 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
352 const struct fatent_operations *ops = sbi->fatent_ops;
353 int err, offset;
354 sector_t blocknr;
355
356 if (!fat_valid_entry(sbi, entry)) {
357 fatent_brelse(fatent);
358 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
359 return -EIO;
360 }
361
362 fatent_set_entry(fatent, entry);
363 ops->ent_blocknr(sb, entry, &offset, &blocknr);
364
365 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
366 fatent_brelse(fatent);
367 err = ops->ent_bread(sb, fatent, offset, blocknr);
368 if (err)
369 return err;
370 }
371 return ops->ent_get(fatent);
372 }
373
374 /* FIXME: We can write the blocks as more big chunk. */
375 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
376 int nr_bhs)
377 {
378 struct msdos_sb_info *sbi = MSDOS_SB(sb);
379 struct buffer_head *c_bh;
380 int err, n, copy;
381
382 err = 0;
383 for (copy = 1; copy < sbi->fats; copy++) {
384 sector_t backup_fat = sbi->fat_length * copy;
385
386 for (n = 0; n < nr_bhs; n++) {
387 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
388 if (!c_bh) {
389 err = -ENOMEM;
390 goto error;
391 }
392 /* Avoid race with userspace read via bdev */
393 lock_buffer(c_bh);
394 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
395 set_buffer_uptodate(c_bh);
396 unlock_buffer(c_bh);
397 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
398 if (sb->s_flags & SB_SYNCHRONOUS)
399 err = sync_dirty_buffer(c_bh);
400 brelse(c_bh);
401 if (err)
402 goto error;
403 }
404 }
405 error:
406 return err;
407 }
408
409 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
410 int new, int wait)
411 {
412 struct super_block *sb = inode->i_sb;
413 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
414 int err;
415
416 ops->ent_put(fatent, new);
417 if (wait) {
418 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
419 if (err)
420 return err;
421 }
422 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
423 }
424
425 static inline int fat_ent_next(struct msdos_sb_info *sbi,
426 struct fat_entry *fatent)
427 {
428 if (sbi->fatent_ops->ent_next(fatent)) {
429 if (fatent->entry < sbi->max_cluster)
430 return 1;
431 }
432 return 0;
433 }
434
435 static inline int fat_ent_read_block(struct super_block *sb,
436 struct fat_entry *fatent)
437 {
438 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
439 sector_t blocknr;
440 int offset;
441
442 fatent_brelse(fatent);
443 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
444 return ops->ent_bread(sb, fatent, offset, blocknr);
445 }
446
447 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
448 struct fat_entry *fatent)
449 {
450 int n, i;
451
452 for (n = 0; n < fatent->nr_bhs; n++) {
453 for (i = 0; i < *nr_bhs; i++) {
454 if (fatent->bhs[n] == bhs[i])
455 break;
456 }
457 if (i == *nr_bhs) {
458 get_bh(fatent->bhs[n]);
459 bhs[i] = fatent->bhs[n];
460 (*nr_bhs)++;
461 }
462 }
463 }
464
465 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
466 {
467 struct super_block *sb = inode->i_sb;
468 struct msdos_sb_info *sbi = MSDOS_SB(sb);
469 const struct fatent_operations *ops = sbi->fatent_ops;
470 struct fat_entry fatent, prev_ent;
471 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
472 int i, count, err, nr_bhs, idx_clus;
473
474 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
475
476 lock_fat(sbi);
477 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
478 sbi->free_clusters < nr_cluster) {
479 unlock_fat(sbi);
480 return -ENOSPC;
481 }
482
483 err = nr_bhs = idx_clus = 0;
484 count = FAT_START_ENT;
485 fatent_init(&prev_ent);
486 fatent_init(&fatent);
487 fatent_set_entry(&fatent, sbi->prev_free + 1);
488 while (count < sbi->max_cluster) {
489 if (fatent.entry >= sbi->max_cluster)
490 fatent.entry = FAT_START_ENT;
491 fatent_set_entry(&fatent, fatent.entry);
492 err = fat_ent_read_block(sb, &fatent);
493 if (err)
494 goto out;
495
496 /* Find the free entries in a block */
497 do {
498 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
499 int entry = fatent.entry;
500
501 /* make the cluster chain */
502 ops->ent_put(&fatent, FAT_ENT_EOF);
503 if (prev_ent.nr_bhs)
504 ops->ent_put(&prev_ent, entry);
505
506 fat_collect_bhs(bhs, &nr_bhs, &fatent);
507
508 sbi->prev_free = entry;
509 if (sbi->free_clusters != -1)
510 sbi->free_clusters--;
511
512 cluster[idx_clus] = entry;
513 idx_clus++;
514 if (idx_clus == nr_cluster)
515 goto out;
516
517 /*
518 * fat_collect_bhs() gets ref-count of bhs,
519 * so we can still use the prev_ent.
520 */
521 prev_ent = fatent;
522 }
523 count++;
524 if (count == sbi->max_cluster)
525 break;
526 } while (fat_ent_next(sbi, &fatent));
527 }
528
529 /* Couldn't allocate the free entries */
530 sbi->free_clusters = 0;
531 sbi->free_clus_valid = 1;
532 err = -ENOSPC;
533
534 out:
535 unlock_fat(sbi);
536 mark_fsinfo_dirty(sb);
537 fatent_brelse(&fatent);
538 if (!err) {
539 if (inode_needs_sync(inode))
540 err = fat_sync_bhs(bhs, nr_bhs);
541 if (!err)
542 err = fat_mirror_bhs(sb, bhs, nr_bhs);
543 }
544 for (i = 0; i < nr_bhs; i++)
545 brelse(bhs[i]);
546
547 if (err && idx_clus)
548 fat_free_clusters(inode, cluster[0]);
549
550 return err;
551 }
552
553 int fat_free_clusters(struct inode *inode, int cluster)
554 {
555 struct super_block *sb = inode->i_sb;
556 struct msdos_sb_info *sbi = MSDOS_SB(sb);
557 const struct fatent_operations *ops = sbi->fatent_ops;
558 struct fat_entry fatent;
559 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
560 int i, err, nr_bhs;
561 int first_cl = cluster, dirty_fsinfo = 0;
562
563 nr_bhs = 0;
564 fatent_init(&fatent);
565 lock_fat(sbi);
566 do {
567 cluster = fat_ent_read(inode, &fatent, cluster);
568 if (cluster < 0) {
569 err = cluster;
570 goto error;
571 } else if (cluster == FAT_ENT_FREE) {
572 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
573 __func__);
574 err = -EIO;
575 goto error;
576 }
577
578 if (sbi->options.discard) {
579 /*
580 * Issue discard for the sectors we no longer
581 * care about, batching contiguous clusters
582 * into one request
583 */
584 if (cluster != fatent.entry + 1) {
585 int nr_clus = fatent.entry - first_cl + 1;
586
587 sb_issue_discard(sb,
588 fat_clus_to_blknr(sbi, first_cl),
589 nr_clus * sbi->sec_per_clus,
590 GFP_NOFS, 0);
591
592 first_cl = cluster;
593 }
594 }
595
596 ops->ent_put(&fatent, FAT_ENT_FREE);
597 if (sbi->free_clusters != -1) {
598 sbi->free_clusters++;
599 dirty_fsinfo = 1;
600 }
601
602 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
603 if (sb->s_flags & SB_SYNCHRONOUS) {
604 err = fat_sync_bhs(bhs, nr_bhs);
605 if (err)
606 goto error;
607 }
608 err = fat_mirror_bhs(sb, bhs, nr_bhs);
609 if (err)
610 goto error;
611 for (i = 0; i < nr_bhs; i++)
612 brelse(bhs[i]);
613 nr_bhs = 0;
614 }
615 fat_collect_bhs(bhs, &nr_bhs, &fatent);
616 } while (cluster != FAT_ENT_EOF);
617
618 if (sb->s_flags & SB_SYNCHRONOUS) {
619 err = fat_sync_bhs(bhs, nr_bhs);
620 if (err)
621 goto error;
622 }
623 err = fat_mirror_bhs(sb, bhs, nr_bhs);
624 error:
625 fatent_brelse(&fatent);
626 for (i = 0; i < nr_bhs; i++)
627 brelse(bhs[i]);
628 unlock_fat(sbi);
629 if (dirty_fsinfo)
630 mark_fsinfo_dirty(sb);
631
632 return err;
633 }
634 EXPORT_SYMBOL_GPL(fat_free_clusters);
635
636 struct fatent_ra {
637 sector_t cur;
638 sector_t limit;
639
640 unsigned int ra_blocks;
641 sector_t ra_advance;
642 sector_t ra_next;
643 sector_t ra_limit;
644 };
645
646 static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra,
647 struct fat_entry *fatent, int ent_limit)
648 {
649 struct msdos_sb_info *sbi = MSDOS_SB(sb);
650 const struct fatent_operations *ops = sbi->fatent_ops;
651 sector_t blocknr, block_end;
652 int offset;
653 /*
654 * This is the sequential read, so ra_pages * 2 (but try to
655 * align the optimal hardware IO size).
656 * [BTW, 128kb covers the whole sectors for FAT12 and FAT16]
657 */
658 unsigned long ra_pages = sb->s_bdi->ra_pages;
659 unsigned int reada_blocks;
660
661 if (fatent->entry >= ent_limit)
662 return;
663
664 if (ra_pages > sb->s_bdi->io_pages)
665 ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages);
666 reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1);
667
668 /* Initialize the range for sequential read */
669 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
670 ops->ent_blocknr(sb, ent_limit - 1, &offset, &block_end);
671 ra->cur = 0;
672 ra->limit = (block_end + 1) - blocknr;
673
674 /* Advancing the window at half size */
675 ra->ra_blocks = reada_blocks >> 1;
676 ra->ra_advance = ra->cur;
677 ra->ra_next = ra->cur;
678 ra->ra_limit = ra->cur + min_t(sector_t, reada_blocks, ra->limit);
679 }
680
681 /* Assuming to be called before reading a new block (increments ->cur). */
682 static void fat_ent_reada(struct super_block *sb, struct fatent_ra *ra,
683 struct fat_entry *fatent)
684 {
685 if (ra->ra_next >= ra->ra_limit)
686 return;
687
688 if (ra->cur >= ra->ra_advance) {
689 struct msdos_sb_info *sbi = MSDOS_SB(sb);
690 const struct fatent_operations *ops = sbi->fatent_ops;
691 struct blk_plug plug;
692 sector_t blocknr, diff;
693 int offset;
694
695 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
696
697 diff = blocknr - ra->cur;
698 blk_start_plug(&plug);
699 /*
700 * FIXME: we would want to directly use the bio with
701 * pages to reduce the number of segments.
702 */
703 for (; ra->ra_next < ra->ra_limit; ra->ra_next++)
704 sb_breadahead(sb, ra->ra_next + diff);
705 blk_finish_plug(&plug);
706
707 /* Advance the readahead window */
708 ra->ra_advance += ra->ra_blocks;
709 ra->ra_limit += min_t(sector_t,
710 ra->ra_blocks, ra->limit - ra->ra_limit);
711 }
712 ra->cur++;
713 }
714
715 int fat_count_free_clusters(struct super_block *sb)
716 {
717 struct msdos_sb_info *sbi = MSDOS_SB(sb);
718 const struct fatent_operations *ops = sbi->fatent_ops;
719 struct fat_entry fatent;
720 struct fatent_ra fatent_ra;
721 int err = 0, free;
722
723 lock_fat(sbi);
724 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
725 goto out;
726
727 free = 0;
728 fatent_init(&fatent);
729 fatent_set_entry(&fatent, FAT_START_ENT);
730 fat_ra_init(sb, &fatent_ra, &fatent, sbi->max_cluster);
731 while (fatent.entry < sbi->max_cluster) {
732 /* readahead of fat blocks */
733 fat_ent_reada(sb, &fatent_ra, &fatent);
734
735 err = fat_ent_read_block(sb, &fatent);
736 if (err)
737 goto out;
738
739 do {
740 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
741 free++;
742 } while (fat_ent_next(sbi, &fatent));
743 cond_resched();
744 }
745 sbi->free_clusters = free;
746 sbi->free_clus_valid = 1;
747 mark_fsinfo_dirty(sb);
748 fatent_brelse(&fatent);
749 out:
750 unlock_fat(sbi);
751 return err;
752 }
753
754 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
755 {
756 struct msdos_sb_info *sbi = MSDOS_SB(sb);
757 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
758 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
759 }
760
761 int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
762 {
763 struct super_block *sb = inode->i_sb;
764 struct msdos_sb_info *sbi = MSDOS_SB(sb);
765 const struct fatent_operations *ops = sbi->fatent_ops;
766 struct fat_entry fatent;
767 struct fatent_ra fatent_ra;
768 u64 ent_start, ent_end, minlen, trimmed = 0;
769 u32 free = 0;
770 int err = 0;
771
772 /*
773 * FAT data is organized as clusters, trim at the granulary of cluster.
774 *
775 * fstrim_range is in byte, convert values to cluster index.
776 * Treat sectors before data region as all used, not to trim them.
777 */
778 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
779 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
780 minlen = range->minlen >> sbi->cluster_bits;
781
782 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
783 return -EINVAL;
784 if (ent_end >= sbi->max_cluster)
785 ent_end = sbi->max_cluster - 1;
786
787 fatent_init(&fatent);
788 lock_fat(sbi);
789 fatent_set_entry(&fatent, ent_start);
790 fat_ra_init(sb, &fatent_ra, &fatent, ent_end + 1);
791 while (fatent.entry <= ent_end) {
792 /* readahead of fat blocks */
793 fat_ent_reada(sb, &fatent_ra, &fatent);
794
795 err = fat_ent_read_block(sb, &fatent);
796 if (err)
797 goto error;
798 do {
799 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
800 free++;
801 } else if (free) {
802 if (free >= minlen) {
803 u32 clus = fatent.entry - free;
804
805 err = fat_trim_clusters(sb, clus, free);
806 if (err && err != -EOPNOTSUPP)
807 goto error;
808 if (!err)
809 trimmed += free;
810 err = 0;
811 }
812 free = 0;
813 }
814 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
815
816 if (fatal_signal_pending(current)) {
817 err = -ERESTARTSYS;
818 goto error;
819 }
820
821 if (need_resched()) {
822 fatent_brelse(&fatent);
823 unlock_fat(sbi);
824 cond_resched();
825 lock_fat(sbi);
826 }
827 }
828 /* handle scenario when tail entries are all free */
829 if (free && free >= minlen) {
830 u32 clus = fatent.entry - free;
831
832 err = fat_trim_clusters(sb, clus, free);
833 if (err && err != -EOPNOTSUPP)
834 goto error;
835 if (!err)
836 trimmed += free;
837 err = 0;
838 }
839
840 error:
841 fatent_brelse(&fatent);
842 unlock_fat(sbi);
843
844 range->len = trimmed << sbi->cluster_bits;
845
846 return err;
847 }
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