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mm/memunmap: don't access uninitialized memmap in memunmap_pages()
[linux-2.6-block.git] / fs / fat / fatent.c
CommitLineData
59bd9ded 1// SPDX-License-Identifier: GPL-2.0-only
1da177e4
LT		 2/*
3 * Copyright (C) 2004, OGAWA Hirofumi
1da177e4
LT		 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 292
306790f7 293 if (is_fat32(sbi)) {
1da177e4
LT		 294 sbi->fatent_shift = 2;
295 sbi->fatent_ops = &fat32_ops;
306790f7 296 } else if (is_fat16(sbi)) {
1da177e4
LT		 297 sbi->fatent_shift = 1;
298 sbi->fatent_ops = &fat16_ops;
306790f7 299 } else if (is_fat12(sbi)) {
1da177e4
LT		 300 sbi->fatent_shift = -1;
301 sbi->fatent_ops = &fat12_ops;
306790f7
CT		 302 } else {
303 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
1da177e4
LT		 304 }
305}
306
90b43665
AB		 307static void mark_fsinfo_dirty(struct super_block *sb)
308{
78491189
AB		 309 struct msdos_sb_info *sbi = MSDOS_SB(sb);
310
306790f7 311 if (sb_rdonly(sb) || !is_fat32(sbi))
78491189
AB		 312 return;
313
314 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
90b43665
AB		 315}
316
1da177e4
LT		 317static inline int fat_ent_update_ptr(struct super_block *sb,
318 struct fat_entry *fatent,
319 int offset, sector_t blocknr)
320{
321 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 322 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 323 struct buffer_head **bhs = fatent->bhs;
324
325 /* Is this fatent's blocks including this entry? */
326 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
327 return 0;
306790f7 328 if (is_fat12(sbi)) {
5e35dd46
OH		 329 if ((offset + 1) < sb->s_blocksize) {
330 /* This entry is on bhs[0]. */
331 if (fatent->nr_bhs == 2) {
332 brelse(bhs[1]);
333 fatent->nr_bhs = 1;
334 }
335 } else {
336 /* This entry needs the next block. */
337 if (fatent->nr_bhs != 2)
338 return 0;
339 if (bhs[1]->b_blocknr != (blocknr + 1))
340 return 0;
341 }
1da177e4
LT		 342 }
343 ops->ent_set_ptr(fatent, offset);
344 return 1;
345}
346
347int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
348{
349 struct super_block *sb = inode->i_sb;
350 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
8992de4c 351 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 352 int err, offset;
353 sector_t blocknr;
354
0afa9626 355 if (!fat_valid_entry(sbi, entry)) {
1da177e4 356 fatent_brelse(fatent);
85c78591 357 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
1da177e4
LT		 358 return -EIO;
359 }
360
361 fatent_set_entry(fatent, entry);
362 ops->ent_blocknr(sb, entry, &offset, &blocknr);
363
364 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
365 fatent_brelse(fatent);
366 err = ops->ent_bread(sb, fatent, offset, blocknr);
367 if (err)
368 return err;
369 }
370 return ops->ent_get(fatent);
371}
372
373/* FIXME: We can write the blocks as more big chunk. */
374static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
375 int nr_bhs)
376{
377 struct msdos_sb_info *sbi = MSDOS_SB(sb);
378 struct buffer_head *c_bh;
379 int err, n, copy;
380
381 err = 0;
382 for (copy = 1; copy < sbi->fats; copy++) {
383 sector_t backup_fat = sbi->fat_length * copy;
384
385 for (n = 0; n < nr_bhs; n++) {
386 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
387 if (!c_bh) {
388 err = -ENOMEM;
389 goto error;
390 }
07bfa441
OH		 391 /* Avoid race with userspace read via bdev */
392 lock_buffer(c_bh);
1da177e4
LT		 393 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
394 set_buffer_uptodate(c_bh);
07bfa441 395 unlock_buffer(c_bh);
b522412a 396 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
1751e8a6 397 if (sb->s_flags & SB_SYNCHRONOUS)
1da177e4
LT		 398 err = sync_dirty_buffer(c_bh);
399 brelse(c_bh);
400 if (err)
401 goto error;
402 }
403 }
404error:
405 return err;
406}
407
408int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
409 int new, int wait)
410{
411 struct super_block *sb = inode->i_sb;
8992de4c 412 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
1da177e4
LT		 413 int err;
414
415 ops->ent_put(fatent, new);
416 if (wait) {
417 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
418 if (err)
419 return err;
420 }
421 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
422}
423
424static inline int fat_ent_next(struct msdos_sb_info *sbi,
425 struct fat_entry *fatent)
426{
427 if (sbi->fatent_ops->ent_next(fatent)) {
428 if (fatent->entry < sbi->max_cluster)
429 return 1;
430 }
431 return 0;
432}
433
434static inline int fat_ent_read_block(struct super_block *sb,
435 struct fat_entry *fatent)
436{
8992de4c 437 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
1da177e4
LT		 438 sector_t blocknr;
439 int offset;
440
441 fatent_brelse(fatent);
442 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
443 return ops->ent_bread(sb, fatent, offset, blocknr);
444}
445
446static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
447 struct fat_entry *fatent)
448{
449 int n, i;
450
451 for (n = 0; n < fatent->nr_bhs; n++) {
452 for (i = 0; i < *nr_bhs; i++) {
453 if (fatent->bhs[n] == bhs[i])
454 break;
455 }
456 if (i == *nr_bhs) {
457 get_bh(fatent->bhs[n]);
458 bhs[i] = fatent->bhs[n];
459 (*nr_bhs)++;
460 }
461 }
462}
463
464int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
465{
466 struct super_block *sb = inode->i_sb;
467 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 468 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 469 struct fat_entry fatent, prev_ent;
470 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
471 int i, count, err, nr_bhs, idx_clus;
472
473 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
474
475 lock_fat(sbi);
606e423e
OH		 476 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
477 sbi->free_clusters < nr_cluster) {
1da177e4
LT		 478 unlock_fat(sbi);
479 return -ENOSPC;
480 }
481
482 err = nr_bhs = idx_clus = 0;
483 count = FAT_START_ENT;
484 fatent_init(&prev_ent);
485 fatent_init(&fatent);
486 fatent_set_entry(&fatent, sbi->prev_free + 1);
487 while (count < sbi->max_cluster) {
488 if (fatent.entry >= sbi->max_cluster)
489 fatent.entry = FAT_START_ENT;
490 fatent_set_entry(&fatent, fatent.entry);
491 err = fat_ent_read_block(sb, &fatent);
492 if (err)
493 goto out;
494
495 /* Find the free entries in a block */
496 do {
497 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
498 int entry = fatent.entry;
499
500 /* make the cluster chain */
501 ops->ent_put(&fatent, FAT_ENT_EOF);
502 if (prev_ent.nr_bhs)
503 ops->ent_put(&prev_ent, entry);
504
505 fat_collect_bhs(bhs, &nr_bhs, &fatent);
506
507 sbi->prev_free = entry;
508 if (sbi->free_clusters != -1)
509 sbi->free_clusters--;
510
511 cluster[idx_clus] = entry;
512 idx_clus++;
513 if (idx_clus == nr_cluster)
514 goto out;
515
516 /*
517 * fat_collect_bhs() gets ref-count of bhs,
518 * so we can still use the prev_ent.
519 */
520 prev_ent = fatent;
521 }
522 count++;
523 if (count == sbi->max_cluster)
524 break;
525 } while (fat_ent_next(sbi, &fatent));
526 }
527
528 /* Couldn't allocate the free entries */
529 sbi->free_clusters = 0;
606e423e 530 sbi->free_clus_valid = 1;
1da177e4
LT		 531 err = -ENOSPC;
532
533out:
534 unlock_fat(sbi);
330fe3c4 535 mark_fsinfo_dirty(sb);
1da177e4
LT		 536 fatent_brelse(&fatent);
537 if (!err) {
538 if (inode_needs_sync(inode))
539 err = fat_sync_bhs(bhs, nr_bhs);
540 if (!err)
541 err = fat_mirror_bhs(sb, bhs, nr_bhs);
542 }
543 for (i = 0; i < nr_bhs; i++)
544 brelse(bhs[i]);
1da177e4
LT		 545
546 if (err && idx_clus)
547 fat_free_clusters(inode, cluster[0]);
548
549 return err;
550}
551
552int fat_free_clusters(struct inode *inode, int cluster)
553{
554 struct super_block *sb = inode->i_sb;
555 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 556 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4
LT		 557 struct fat_entry fatent;
558 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
559 int i, err, nr_bhs;
330fe3c4 560 int first_cl = cluster, dirty_fsinfo = 0;
1da177e4
LT		 561
562 nr_bhs = 0;
563 fatent_init(&fatent);
564 lock_fat(sbi);
565 do {
566 cluster = fat_ent_read(inode, &fatent, cluster);
567 if (cluster < 0) {
568 err = cluster;
569 goto error;
570 } else if (cluster == FAT_ENT_FREE) {
85c78591 571 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
8e24eea7 572 __func__);
1da177e4
LT		 573 err = -EIO;
574 goto error;
575 }
576
681142f9
CH		 577 if (sbi->options.discard) {
578 /*
579 * Issue discard for the sectors we no longer
580 * care about, batching contiguous clusters
581 * into one request
582 */
583 if (cluster != fatent.entry + 1) {
584 int nr_clus = fatent.entry - first_cl + 1;
585
586 sb_issue_discard(sb,
587 fat_clus_to_blknr(sbi, first_cl),
2cf6d26a 588 nr_clus * sbi->sec_per_clus,
dd3932ed 589 GFP_NOFS, 0);
681142f9
CH		 590
591 first_cl = cluster;
592 }
8c540a96
DW		 593 }
594
1da177e4 595 ops->ent_put(&fatent, FAT_ENT_FREE);
a6bf6b21 596 if (sbi->free_clusters != -1) {
1da177e4 597 sbi->free_clusters++;
330fe3c4 598 dirty_fsinfo = 1;
a6bf6b21 599 }
1da177e4
LT		 600
601 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
1751e8a6 602 if (sb->s_flags & SB_SYNCHRONOUS) {
1da177e4
LT		 603 err = fat_sync_bhs(bhs, nr_bhs);
604 if (err)
605 goto error;
606 }
607 err = fat_mirror_bhs(sb, bhs, nr_bhs);
608 if (err)
609 goto error;
610 for (i = 0; i < nr_bhs; i++)
611 brelse(bhs[i]);
612 nr_bhs = 0;
613 }
614 fat_collect_bhs(bhs, &nr_bhs, &fatent);
615 } while (cluster != FAT_ENT_EOF);
616
1751e8a6 617 if (sb->s_flags & SB_SYNCHRONOUS) {
1da177e4
LT		 618 err = fat_sync_bhs(bhs, nr_bhs);
619 if (err)
620 goto error;
621 }
622 err = fat_mirror_bhs(sb, bhs, nr_bhs);
623error:
624 fatent_brelse(&fatent);
625 for (i = 0; i < nr_bhs; i++)
626 brelse(bhs[i]);
627 unlock_fat(sbi);
330fe3c4
AB		 628 if (dirty_fsinfo)
629 mark_fsinfo_dirty(sb);
1da177e4 630
1da177e4
LT		 631 return err;
632}
7c709d00 633EXPORT_SYMBOL_GPL(fat_free_clusters);
1da177e4 634
9f966be8
OH		 635/* 128kb is the whole sectors for FAT12 and FAT16 */
636#define FAT_READA_SIZE (128 * 1024)
637
638static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
639 unsigned long reada_blocks)
640{
8992de4c 641 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
9f966be8
OH		 642 sector_t blocknr;
643 int i, offset;
644
645 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
646
647 for (i = 0; i < reada_blocks; i++)
648 sb_breadahead(sb, blocknr + i);
649}
650
1da177e4
LT		 651int fat_count_free_clusters(struct super_block *sb)
652{
653 struct msdos_sb_info *sbi = MSDOS_SB(sb);
8992de4c 654 const struct fatent_operations *ops = sbi->fatent_ops;
1da177e4 655 struct fat_entry fatent;
9f966be8 656 unsigned long reada_blocks, reada_mask, cur_block;
1da177e4
LT		 657 int err = 0, free;
658
659 lock_fat(sbi);
606e423e 660 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
1da177e4
LT		 661 goto out;
662
9f966be8
OH		 663 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
664 reada_mask = reada_blocks - 1;
665 cur_block = 0;
666
1da177e4
LT		 667 free = 0;
668 fatent_init(&fatent);
669 fatent_set_entry(&fatent, FAT_START_ENT);
670 while (fatent.entry < sbi->max_cluster) {
9f966be8
OH		 671 /* readahead of fat blocks */
672 if ((cur_block & reada_mask) == 0) {
673 unsigned long rest = sbi->fat_length - cur_block;
674 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
675 }
676 cur_block++;
677
1da177e4
LT		 678 err = fat_ent_read_block(sb, &fatent);
679 if (err)
680 goto out;
681
682 do {
683 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
684 free++;
685 } while (fat_ent_next(sbi, &fatent));
ac081c3b 686 cond_resched();
1da177e4
LT		 687 }
688 sbi->free_clusters = free;
606e423e 689 sbi->free_clus_valid = 1;
90b43665 690 mark_fsinfo_dirty(sb);
1da177e4
LT		 691 fatent_brelse(&fatent);
692out:
693 unlock_fat(sbi);
694 return err;
695}
f663b5b3
WW		 696
697static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
698{
699 struct msdos_sb_info *sbi = MSDOS_SB(sb);
700 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
701 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
702}
703
704int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
705{
706 struct super_block *sb = inode->i_sb;
707 struct msdos_sb_info *sbi = MSDOS_SB(sb);
708 const struct fatent_operations *ops = sbi->fatent_ops;
709 struct fat_entry fatent;
710 u64 ent_start, ent_end, minlen, trimmed = 0;
711 u32 free = 0;
712 unsigned long reada_blocks, reada_mask, cur_block = 0;
713 int err = 0;
714
715 /*
716 * FAT data is organized as clusters, trim at the granulary of cluster.
717 *
718 * fstrim_range is in byte, convert vaules to cluster index.
719 * Treat sectors before data region as all used, not to trim them.
720 */
721 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
722 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
723 minlen = range->minlen >> sbi->cluster_bits;
724
725 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
726 return -EINVAL;
727 if (ent_end >= sbi->max_cluster)
728 ent_end = sbi->max_cluster - 1;
729
730 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
731 reada_mask = reada_blocks - 1;
732
733 fatent_init(&fatent);
734 lock_fat(sbi);
735 fatent_set_entry(&fatent, ent_start);
736 while (fatent.entry <= ent_end) {
737 /* readahead of fat blocks */
738 if ((cur_block & reada_mask) == 0) {
739 unsigned long rest = sbi->fat_length - cur_block;
740 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
741 }
742 cur_block++;
743
744 err = fat_ent_read_block(sb, &fatent);
745 if (err)
746 goto error;
747 do {
748 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
749 free++;
750 } else if (free) {
751 if (free >= minlen) {
752 u32 clus = fatent.entry - free;
753
754 err = fat_trim_clusters(sb, clus, free);
755 if (err && err != -EOPNOTSUPP)
756 goto error;
757 if (!err)
758 trimmed += free;
759 err = 0;
760 }
761 free = 0;
762 }
763 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
764
765 if (fatal_signal_pending(current)) {
766 err = -ERESTARTSYS;
767 goto error;
768 }
769
770 if (need_resched()) {
771 fatent_brelse(&fatent);
772 unlock_fat(sbi);
773 cond_resched();
774 lock_fat(sbi);
775 }
776 }
777 /* handle scenario when tail entries are all free */
778 if (free && free >= minlen) {
779 u32 clus = fatent.entry - free;
780
781 err = fat_trim_clusters(sb, clus, free);
782 if (err && err != -EOPNOTSUPP)
783 goto error;
784 if (!err)
785 trimmed += free;
786 err = 0;
787 }
788
789error:
790 fatent_brelse(&fatent);
791 unlock_fat(sbi);
792
793 range->len = trimmed << sbi->cluster_bits;
794
795 return err;
796}
Linux 6.x block layer and io_uring tree(s)