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1/*
2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
4 */
5
6#include <linux/module.h>
7#include <linux/fs.h>
8#include <linux/msdos_fs.h>
9#include <linux/blkdev.h>
10#include "fat.h"
11
12struct fatent_operations {
13 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
14 void (*ent_set_ptr)(struct fat_entry *, int);
15 int (*ent_bread)(struct super_block *, struct fat_entry *,
16 int, sector_t);
17 int (*ent_get)(struct fat_entry *);
18 void (*ent_put)(struct fat_entry *, int);
19 int (*ent_next)(struct fat_entry *);
20};
21
22static DEFINE_SPINLOCK(fat12_entry_lock);
23
24static void fat12_ent_blocknr(struct super_block *sb, int entry,
25 int *offset, sector_t *blocknr)
26{
27 struct msdos_sb_info *sbi = MSDOS_SB(sb);
28 int bytes = entry + (entry >> 1);
29 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
30 *offset = bytes & (sb->s_blocksize - 1);
31 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
32}
33
34static void fat_ent_blocknr(struct super_block *sb, int entry,
35 int *offset, sector_t *blocknr)
36{
37 struct msdos_sb_info *sbi = MSDOS_SB(sb);
38 int bytes = (entry << sbi->fatent_shift);
39 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
40 *offset = bytes & (sb->s_blocksize - 1);
41 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
42}
43
44static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
45{
46 struct buffer_head **bhs = fatent->bhs;
47 if (fatent->nr_bhs == 1) {
48 WARN_ON(offset >= (bhs[0]->b_size - 1));
49 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
50 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
51 } else {
52 WARN_ON(offset != (bhs[0]->b_size - 1));
53 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
54 fatent->u.ent12_p[1] = bhs[1]->b_data;
55 }
56}
57
58static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
59{
60 WARN_ON(offset & (2 - 1));
61 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
62}
63
64static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
65{
66 WARN_ON(offset & (4 - 1));
67 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
68}
69
70static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
71 int offset, sector_t blocknr)
72{
73 struct buffer_head **bhs = fatent->bhs;
74
75 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
76 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
77
78 bhs[0] = sb_bread(sb, blocknr);
79 if (!bhs[0])
80 goto err;
81
82 if ((offset + 1) < sb->s_blocksize)
83 fatent->nr_bhs = 1;
84 else {
85 /* This entry is block boundary, it needs the next block */
86 blocknr++;
87 bhs[1] = sb_bread(sb, blocknr);
88 if (!bhs[1])
89 goto err_brelse;
90 fatent->nr_bhs = 2;
91 }
92 fat12_ent_set_ptr(fatent, offset);
93 return 0;
94
95err_brelse:
96 brelse(bhs[0]);
97err:
98 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
99 return -EIO;
100}
101
102static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
103 int offset, sector_t blocknr)
104{
105 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
106
107 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
108 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
109 fatent->bhs[0] = sb_bread(sb, blocknr);
110 if (!fatent->bhs[0]) {
111 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
112 (llu)blocknr);
113 return -EIO;
114 }
115 fatent->nr_bhs = 1;
116 ops->ent_set_ptr(fatent, offset);
117 return 0;
118}
119
120static int fat12_ent_get(struct fat_entry *fatent)
121{
122 u8 **ent12_p = fatent->u.ent12_p;
123 int next;
124
125 spin_lock(&fat12_entry_lock);
126 if (fatent->entry & 1)
127 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
128 else
129 next = (*ent12_p[1] << 8) | *ent12_p[0];
130 spin_unlock(&fat12_entry_lock);
131
132 next &= 0x0fff;
133 if (next >= BAD_FAT12)
134 next = FAT_ENT_EOF;
135 return next;
136}
137
138static int fat16_ent_get(struct fat_entry *fatent)
139{
140 int next = le16_to_cpu(*fatent->u.ent16_p);
141 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
142 if (next >= BAD_FAT16)
143 next = FAT_ENT_EOF;
144 return next;
145}
146
147static int fat32_ent_get(struct fat_entry *fatent)
148{
149 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
150 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
151 if (next >= BAD_FAT32)
152 next = FAT_ENT_EOF;
153 return next;
154}
155
156static void fat12_ent_put(struct fat_entry *fatent, int new)
157{
158 u8 **ent12_p = fatent->u.ent12_p;
159
160 if (new == FAT_ENT_EOF)
161 new = EOF_FAT12;
162
163 spin_lock(&fat12_entry_lock);
164 if (fatent->entry & 1) {
165 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
166 *ent12_p[1] = new >> 4;
167 } else {
168 *ent12_p[0] = new & 0xff;
169 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
170 }
171 spin_unlock(&fat12_entry_lock);
172
173 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
174 if (fatent->nr_bhs == 2)
175 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode);
176}
177
178static void fat16_ent_put(struct fat_entry *fatent, int new)
179{
180 if (new == FAT_ENT_EOF)
181 new = EOF_FAT16;
182
183 *fatent->u.ent16_p = cpu_to_le16(new);
184 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
185}
186
187static void fat32_ent_put(struct fat_entry *fatent, int new)
188{
189 WARN_ON(new & 0xf0000000);
190 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
191 *fatent->u.ent32_p = cpu_to_le32(new);
192 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
193}
194
195static int fat12_ent_next(struct fat_entry *fatent)
196{
197 u8 **ent12_p = fatent->u.ent12_p;
198 struct buffer_head **bhs = fatent->bhs;
199 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
200
201 fatent->entry++;
202 if (fatent->nr_bhs == 1) {
203 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data +
204 (bhs[0]->b_size - 2)));
205 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data +
206 (bhs[0]->b_size - 1)));
207 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
208 ent12_p[0] = nextp - 1;
209 ent12_p[1] = nextp;
210 return 1;
211 }
212 } else {
213 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data +
214 (bhs[0]->b_size - 1)));
215 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
216 ent12_p[0] = nextp - 1;
217 ent12_p[1] = nextp;
218 brelse(bhs[0]);
219 bhs[0] = bhs[1];
220 fatent->nr_bhs = 1;
221 return 1;
222 }
223 ent12_p[0] = NULL;
224 ent12_p[1] = NULL;
225 return 0;
226}
227
228static int fat16_ent_next(struct fat_entry *fatent)
229{
230 const struct buffer_head *bh = fatent->bhs[0];
231 fatent->entry++;
232 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
233 fatent->u.ent16_p++;
234 return 1;
235 }
236 fatent->u.ent16_p = NULL;
237 return 0;
238}
239
240static int fat32_ent_next(struct fat_entry *fatent)
241{
242 const struct buffer_head *bh = fatent->bhs[0];
243 fatent->entry++;
244 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
245 fatent->u.ent32_p++;
246 return 1;
247 }
248 fatent->u.ent32_p = NULL;
249 return 0;
250}
251
252static struct fatent_operations fat12_ops = {
253 .ent_blocknr = fat12_ent_blocknr,
254 .ent_set_ptr = fat12_ent_set_ptr,
255 .ent_bread = fat12_ent_bread,
256 .ent_get = fat12_ent_get,
257 .ent_put = fat12_ent_put,
258 .ent_next = fat12_ent_next,
259};
260
261static struct fatent_operations fat16_ops = {
262 .ent_blocknr = fat_ent_blocknr,
263 .ent_set_ptr = fat16_ent_set_ptr,
264 .ent_bread = fat_ent_bread,
265 .ent_get = fat16_ent_get,
266 .ent_put = fat16_ent_put,
267 .ent_next = fat16_ent_next,
268};
269
270static struct fatent_operations fat32_ops = {
271 .ent_blocknr = fat_ent_blocknr,
272 .ent_set_ptr = fat32_ent_set_ptr,
273 .ent_bread = fat_ent_bread,
274 .ent_get = fat32_ent_get,
275 .ent_put = fat32_ent_put,
276 .ent_next = fat32_ent_next,
277};
278
279static inline void lock_fat(struct msdos_sb_info *sbi)
280{
281 mutex_lock(&sbi->fat_lock);
282}
283
284static inline void unlock_fat(struct msdos_sb_info *sbi)
285{
286 mutex_unlock(&sbi->fat_lock);
287}
288
289void fat_ent_access_init(struct super_block *sb)
290{
291 struct msdos_sb_info *sbi = MSDOS_SB(sb);
292
293 mutex_init(&sbi->fat_lock);
294
295 switch (sbi->fat_bits) {
296 case 32:
297 sbi->fatent_shift = 2;
298 sbi->fatent_ops = &fat32_ops;
299 break;
300 case 16:
301 sbi->fatent_shift = 1;
302 sbi->fatent_ops = &fat16_ops;
303 break;
304 case 12:
305 sbi->fatent_shift = -1;
306 sbi->fatent_ops = &fat12_ops;
307 break;
308 }
309}
310
311static void mark_fsinfo_dirty(struct super_block *sb)
312{
313 struct msdos_sb_info *sbi = MSDOS_SB(sb);
314
315 if (sb->s_flags & MS_RDONLY || sbi->fat_bits != 32)
316 return;
317
318 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
319}
320
321static inline int fat_ent_update_ptr(struct super_block *sb,
322 struct fat_entry *fatent,
323 int offset, sector_t blocknr)
324{
325 struct msdos_sb_info *sbi = MSDOS_SB(sb);
326 struct fatent_operations *ops = sbi->fatent_ops;
327 struct buffer_head **bhs = fatent->bhs;
328
329 /* Is this fatent's blocks including this entry? */
330 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
331 return 0;
332 if (sbi->fat_bits == 12) {
333 if ((offset + 1) < sb->s_blocksize) {
334 /* This entry is on bhs[0]. */
335 if (fatent->nr_bhs == 2) {
336 brelse(bhs[1]);
337 fatent->nr_bhs = 1;
338 }
339 } else {
340 /* This entry needs the next block. */
341 if (fatent->nr_bhs != 2)
342 return 0;
343 if (bhs[1]->b_blocknr != (blocknr + 1))
344 return 0;
345 }
346 }
347 ops->ent_set_ptr(fatent, offset);
348 return 1;
349}
350
351int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
352{
353 struct super_block *sb = inode->i_sb;
354 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
355 struct fatent_operations *ops = sbi->fatent_ops;
356 int err, offset;
357 sector_t blocknr;
358
359 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
360 fatent_brelse(fatent);
361 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
362 return -EIO;
363 }
364
365 fatent_set_entry(fatent, entry);
366 ops->ent_blocknr(sb, entry, &offset, &blocknr);
367
368 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
369 fatent_brelse(fatent);
370 err = ops->ent_bread(sb, fatent, offset, blocknr);
371 if (err)
372 return err;
373 }
374 return ops->ent_get(fatent);
375}
376
377/* FIXME: We can write the blocks as more big chunk. */
378static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
379 int nr_bhs)
380{
381 struct msdos_sb_info *sbi = MSDOS_SB(sb);
382 struct buffer_head *c_bh;
383 int err, n, copy;
384
385 err = 0;
386 for (copy = 1; copy < sbi->fats; copy++) {
387 sector_t backup_fat = sbi->fat_length * copy;
388
389 for (n = 0; n < nr_bhs; n++) {
390 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
391 if (!c_bh) {
392 err = -ENOMEM;
393 goto error;
394 }
395 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
396 set_buffer_uptodate(c_bh);
397 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
398 if (sb->s_flags & MS_SYNCHRONOUS)
399 err = sync_dirty_buffer(c_bh);
400 brelse(c_bh);
401 if (err)
402 goto error;
403 }
404 }
405error:
406 return err;
407}
408
409int 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 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
425static 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
435static inline int fat_ent_read_block(struct super_block *sb,
436 struct fat_entry *fatent)
437{
438 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
447static 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
465int 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 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
534out:
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
553int 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 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 & MS_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 & MS_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);
624error:
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}
634EXPORT_SYMBOL_GPL(fat_free_clusters);
635
636/* 128kb is the whole sectors for FAT12 and FAT16 */
637#define FAT_READA_SIZE (128 * 1024)
638
639static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
640 unsigned long reada_blocks)
641{
642 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
643 sector_t blocknr;
644 int i, offset;
645
646 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
647
648 for (i = 0; i < reada_blocks; i++)
649 sb_breadahead(sb, blocknr + i);
650}
651
652int fat_count_free_clusters(struct super_block *sb)
653{
654 struct msdos_sb_info *sbi = MSDOS_SB(sb);
655 struct fatent_operations *ops = sbi->fatent_ops;
656 struct fat_entry fatent;
657 unsigned long reada_blocks, reada_mask, cur_block;
658 int err = 0, free;
659
660 lock_fat(sbi);
661 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
662 goto out;
663
664 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
665 reada_mask = reada_blocks - 1;
666 cur_block = 0;
667
668 free = 0;
669 fatent_init(&fatent);
670 fatent_set_entry(&fatent, FAT_START_ENT);
671 while (fatent.entry < sbi->max_cluster) {
672 /* readahead of fat blocks */
673 if ((cur_block & reada_mask) == 0) {
674 unsigned long rest = sbi->fat_length - cur_block;
675 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
676 }
677 cur_block++;
678
679 err = fat_ent_read_block(sb, &fatent);
680 if (err)
681 goto out;
682
683 do {
684 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
685 free++;
686 } while (fat_ent_next(sbi, &fatent));
687 }
688 sbi->free_clusters = free;
689 sbi->free_clus_valid = 1;
690 mark_fsinfo_dirty(sb);
691 fatent_brelse(&fatent);
692out:
693 unlock_fat(sbi);
694 return err;
695}
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 "fat.h"
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
20static DEFINE_SPINLOCK(fat12_entry_lock);
21
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);
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
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);
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
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);
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
93err_brelse:
94 brelse(bhs[0]);
95err:
96 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
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{
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
118static 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
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
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
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);
182 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
183}
184
185static 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
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) {
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
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
250static 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
259static 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
268static 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
277static inline void lock_fat(struct msdos_sb_info *sbi)
278{
279 mutex_lock(&sbi->fat_lock);
280}
281
282static inline void unlock_fat(struct msdos_sb_info *sbi)
283{
284 mutex_unlock(&sbi->fat_lock);
285}
286
287void 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 if (is_fat32(sbi)) {
294 sbi->fatent_shift = 2;
295 sbi->fatent_ops = &fat32_ops;
296 } else if (is_fat16(sbi)) {
297 sbi->fatent_shift = 1;
298 sbi->fatent_ops = &fat16_ops;
299 } else if (is_fat12(sbi)) {
300 sbi->fatent_shift = -1;
301 sbi->fatent_ops = &fat12_ops;
302 } else {
303 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
304 }
305}
306
307static void mark_fsinfo_dirty(struct super_block *sb)
308{
309 struct msdos_sb_info *sbi = MSDOS_SB(sb);
310
311 if (sb_rdonly(sb) || !is_fat32(sbi))
312 return;
313
314 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
315}
316
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);
322 const struct fatent_operations *ops = sbi->fatent_ops;
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;
328 if (is_fat12(sbi)) {
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 }
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);
351 const struct fatent_operations *ops = sbi->fatent_ops;
352 int err, offset;
353 sector_t blocknr;
354
355 if (!fat_valid_entry(sbi, entry)) {
356 fatent_brelse(fatent);
357 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
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 }
391 /* Avoid race with userspace read via bdev */
392 lock_buffer(c_bh);
393 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
394 set_buffer_uptodate(c_bh);
395 unlock_buffer(c_bh);
396 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
397 if (sb->s_flags & SB_SYNCHRONOUS)
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;
412 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
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{
437 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
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);
468 const struct fatent_operations *ops = sbi->fatent_ops;
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);
476 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
477 sbi->free_clusters < nr_cluster) {
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;
530 sbi->free_clus_valid = 1;
531 err = -ENOSPC;
532
533out:
534 unlock_fat(sbi);
535 mark_fsinfo_dirty(sb);
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]);
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);
556 const struct fatent_operations *ops = sbi->fatent_ops;
557 struct fat_entry fatent;
558 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
559 int i, err, nr_bhs;
560 int first_cl = cluster, dirty_fsinfo = 0;
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) {
571 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
572 __func__);
573 err = -EIO;
574 goto error;
575 }
576
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),
588 nr_clus * sbi->sec_per_clus,
589 GFP_NOFS, 0);
590
591 first_cl = cluster;
592 }
593 }
594
595 ops->ent_put(&fatent, FAT_ENT_FREE);
596 if (sbi->free_clusters != -1) {
597 sbi->free_clusters++;
598 dirty_fsinfo = 1;
599 }
600
601 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
602 if (sb->s_flags & SB_SYNCHRONOUS) {
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
617 if (sb->s_flags & SB_SYNCHRONOUS) {
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);
628 if (dirty_fsinfo)
629 mark_fsinfo_dirty(sb);
630
631 return err;
632}
633EXPORT_SYMBOL_GPL(fat_free_clusters);
634
635struct fatent_ra {
636 sector_t cur;
637 sector_t limit;
638
639 unsigned int ra_blocks;
640 sector_t ra_advance;
641 sector_t ra_next;
642 sector_t ra_limit;
643};
644
645static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra,
646 struct fat_entry *fatent, int ent_limit)
647{
648 struct msdos_sb_info *sbi = MSDOS_SB(sb);
649 const struct fatent_operations *ops = sbi->fatent_ops;
650 sector_t blocknr, block_end;
651 int offset;
652 /*
653 * This is the sequential read, so ra_pages * 2 (but try to
654 * align the optimal hardware IO size).
655 * [BTW, 128kb covers the whole sectors for FAT12 and FAT16]
656 */
657 unsigned long ra_pages = sb->s_bdi->ra_pages;
658 unsigned int reada_blocks;
659
660 if (fatent->entry >= ent_limit)
661 return;
662
663 if (ra_pages > sb->s_bdi->io_pages)
664 ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages);
665 reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1);
666
667 /* Initialize the range for sequential read */
668 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
669 ops->ent_blocknr(sb, ent_limit - 1, &offset, &block_end);
670 ra->cur = 0;
671 ra->limit = (block_end + 1) - blocknr;
672
673 /* Advancing the window at half size */
674 ra->ra_blocks = reada_blocks >> 1;
675 ra->ra_advance = ra->cur;
676 ra->ra_next = ra->cur;
677 ra->ra_limit = ra->cur + min_t(sector_t, reada_blocks, ra->limit);
678}
679
680/* Assuming to be called before reading a new block (increments ->cur). */
681static void fat_ent_reada(struct super_block *sb, struct fatent_ra *ra,
682 struct fat_entry *fatent)
683{
684 if (ra->ra_next >= ra->ra_limit)
685 return;
686
687 if (ra->cur >= ra->ra_advance) {
688 struct msdos_sb_info *sbi = MSDOS_SB(sb);
689 const struct fatent_operations *ops = sbi->fatent_ops;
690 struct blk_plug plug;
691 sector_t blocknr, diff;
692 int offset;
693
694 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
695
696 diff = blocknr - ra->cur;
697 blk_start_plug(&plug);
698 /*
699 * FIXME: we would want to directly use the bio with
700 * pages to reduce the number of segments.
701 */
702 for (; ra->ra_next < ra->ra_limit; ra->ra_next++)
703 sb_breadahead(sb, ra->ra_next + diff);
704 blk_finish_plug(&plug);
705
706 /* Advance the readahead window */
707 ra->ra_advance += ra->ra_blocks;
708 ra->ra_limit += min_t(sector_t,
709 ra->ra_blocks, ra->limit - ra->ra_limit);
710 }
711 ra->cur++;
712}
713
714int fat_count_free_clusters(struct super_block *sb)
715{
716 struct msdos_sb_info *sbi = MSDOS_SB(sb);
717 const struct fatent_operations *ops = sbi->fatent_ops;
718 struct fat_entry fatent;
719 struct fatent_ra fatent_ra;
720 int err = 0, free;
721
722 lock_fat(sbi);
723 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
724 goto out;
725
726 free = 0;
727 fatent_init(&fatent);
728 fatent_set_entry(&fatent, FAT_START_ENT);
729 fat_ra_init(sb, &fatent_ra, &fatent, sbi->max_cluster);
730 while (fatent.entry < sbi->max_cluster) {
731 /* readahead of fat blocks */
732 fat_ent_reada(sb, &fatent_ra, &fatent);
733
734 err = fat_ent_read_block(sb, &fatent);
735 if (err)
736 goto out;
737
738 do {
739 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
740 free++;
741 } while (fat_ent_next(sbi, &fatent));
742 cond_resched();
743 }
744 sbi->free_clusters = free;
745 sbi->free_clus_valid = 1;
746 mark_fsinfo_dirty(sb);
747 fatent_brelse(&fatent);
748out:
749 unlock_fat(sbi);
750 return err;
751}
752
753static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
754{
755 struct msdos_sb_info *sbi = MSDOS_SB(sb);
756 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
757 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
758}
759
760int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
761{
762 struct super_block *sb = inode->i_sb;
763 struct msdos_sb_info *sbi = MSDOS_SB(sb);
764 const struct fatent_operations *ops = sbi->fatent_ops;
765 struct fat_entry fatent;
766 struct fatent_ra fatent_ra;
767 u64 ent_start, ent_end, minlen, trimmed = 0;
768 u32 free = 0;
769 int err = 0;
770
771 /*
772 * FAT data is organized as clusters, trim at the granulary of cluster.
773 *
774 * fstrim_range is in byte, convert vaules to cluster index.
775 * Treat sectors before data region as all used, not to trim them.
776 */
777 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
778 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
779 minlen = range->minlen >> sbi->cluster_bits;
780
781 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
782 return -EINVAL;
783 if (ent_end >= sbi->max_cluster)
784 ent_end = sbi->max_cluster - 1;
785
786 fatent_init(&fatent);
787 lock_fat(sbi);
788 fatent_set_entry(&fatent, ent_start);
789 fat_ra_init(sb, &fatent_ra, &fatent, ent_end + 1);
790 while (fatent.entry <= ent_end) {
791 /* readahead of fat blocks */
792 fat_ent_reada(sb, &fatent_ra, &fatent);
793
794 err = fat_ent_read_block(sb, &fatent);
795 if (err)
796 goto error;
797 do {
798 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
799 free++;
800 } else if (free) {
801 if (free >= minlen) {
802 u32 clus = fatent.entry - free;
803
804 err = fat_trim_clusters(sb, clus, free);
805 if (err && err != -EOPNOTSUPP)
806 goto error;
807 if (!err)
808 trimmed += free;
809 err = 0;
810 }
811 free = 0;
812 }
813 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
814
815 if (fatal_signal_pending(current)) {
816 err = -ERESTARTSYS;
817 goto error;
818 }
819
820 if (need_resched()) {
821 fatent_brelse(&fatent);
822 unlock_fat(sbi);
823 cond_resched();
824 lock_fat(sbi);
825 }
826 }
827 /* handle scenario when tail entries are all free */
828 if (free && free >= minlen) {
829 u32 clus = fatent.entry - free;
830
831 err = fat_trim_clusters(sb, clus, free);
832 if (err && err != -EOPNOTSUPP)
833 goto error;
834 if (!err)
835 trimmed += free;
836 err = 0;
837 }
838
839error:
840 fatent_brelse(&fatent);
841 unlock_fat(sbi);
842
843 range->len = trimmed << sbi->cluster_bits;
844
845 return err;
846}