2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
6 #include <linux/module.h>
8 #include <linux/msdos_fs.h>
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 *,
15 int (*ent_get)(struct fat_entry *);
16 void (*ent_put)(struct fat_entry *, int);
17 int (*ent_next)(struct fat_entry *);
20 static void fat12_ent_blocknr(struct super_block *sb, int entry,
21 int *offset, sector_t *blocknr)
23 struct msdos_sb_info *sbi = MSDOS_SB(sb);
24 int bytes = entry + (entry >> 1);
25 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
26 *offset = bytes & (sb->s_blocksize - 1);
27 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
30 static void fat_ent_blocknr(struct super_block *sb, int entry,
31 int *offset, sector_t *blocknr)
33 struct msdos_sb_info *sbi = MSDOS_SB(sb);
34 int bytes = (entry << sbi->fatent_shift);
35 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
36 *offset = bytes & (sb->s_blocksize - 1);
37 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
40 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
42 struct buffer_head **bhs = fatent->bhs;
43 if (fatent->nr_bhs == 1) {
44 WARN_ON(offset >= (bhs[0]->b_size - 1));
45 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
46 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 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[1]->b_data;
54 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
56 WARN_ON(offset & (2 - 1));
57 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
60 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
62 WARN_ON(offset & (4 - 1));
63 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
66 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
67 int offset, sector_t blocknr)
69 struct buffer_head **bhs = fatent->bhs;
71 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
72 bhs[0] = sb_bread(sb, blocknr);
76 if ((offset + 1) < sb->s_blocksize)
79 /* This entry is block boundary, it needs the next block */
81 bhs[1] = sb_bread(sb, blocknr);
86 fat12_ent_set_ptr(fatent, offset);
92 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
93 (unsigned long long)blocknr);
97 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
98 int offset, sector_t blocknr)
100 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
102 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
103 fatent->bhs[0] = sb_bread(sb, blocknr);
104 if (!fatent->bhs[0]) {
105 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
106 (unsigned long long)blocknr);
110 ops->ent_set_ptr(fatent, offset);
114 static int fat12_ent_get(struct fat_entry *fatent)
116 u8 **ent12_p = fatent->u.ent12_p;
119 if (fatent->entry & 1)
120 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
122 next = (*ent12_p[1] << 8) | *ent12_p[0];
124 if (next >= BAD_FAT12)
129 static int fat16_ent_get(struct fat_entry *fatent)
131 int next = le16_to_cpu(*fatent->u.ent16_p);
132 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
133 if (next >= BAD_FAT16)
138 static int fat32_ent_get(struct fat_entry *fatent)
140 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
141 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
142 if (next >= BAD_FAT32)
147 static void fat12_ent_put(struct fat_entry *fatent, int new)
149 u8 **ent12_p = fatent->u.ent12_p;
151 if (new == FAT_ENT_EOF)
154 if (fatent->entry & 1) {
155 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
156 *ent12_p[1] = new >> 4;
158 *ent12_p[0] = new & 0xff;
159 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
162 mark_buffer_dirty(fatent->bhs[0]);
163 if (fatent->nr_bhs == 2)
164 mark_buffer_dirty(fatent->bhs[1]);
167 static void fat16_ent_put(struct fat_entry *fatent, int new)
169 if (new == FAT_ENT_EOF)
172 *fatent->u.ent16_p = cpu_to_le16(new);
173 mark_buffer_dirty(fatent->bhs[0]);
176 static void fat32_ent_put(struct fat_entry *fatent, int new)
178 if (new == FAT_ENT_EOF)
181 WARN_ON(new & 0xf0000000);
182 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
183 *fatent->u.ent32_p = cpu_to_le32(new);
184 mark_buffer_dirty(fatent->bhs[0]);
187 static int fat12_ent_next(struct fat_entry *fatent)
189 u8 **ent12_p = fatent->u.ent12_p;
190 struct buffer_head **bhs = fatent->bhs;
191 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
194 if (fatent->nr_bhs == 1) {
195 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
196 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
197 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
198 ent12_p[0] = nextp - 1;
203 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
204 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
205 ent12_p[0] = nextp - 1;
217 static int fat16_ent_next(struct fat_entry *fatent)
219 const struct buffer_head *bh = fatent->bhs[0];
221 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
225 fatent->u.ent16_p = NULL;
229 static int fat32_ent_next(struct fat_entry *fatent)
231 const struct buffer_head *bh = fatent->bhs[0];
233 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
237 fatent->u.ent32_p = NULL;
241 static struct fatent_operations fat12_ops = {
242 .ent_blocknr = fat12_ent_blocknr,
243 .ent_set_ptr = fat12_ent_set_ptr,
244 .ent_bread = fat12_ent_bread,
245 .ent_get = fat12_ent_get,
246 .ent_put = fat12_ent_put,
247 .ent_next = fat12_ent_next,
250 static struct fatent_operations fat16_ops = {
251 .ent_blocknr = fat_ent_blocknr,
252 .ent_set_ptr = fat16_ent_set_ptr,
253 .ent_bread = fat_ent_bread,
254 .ent_get = fat16_ent_get,
255 .ent_put = fat16_ent_put,
256 .ent_next = fat16_ent_next,
259 static struct fatent_operations fat32_ops = {
260 .ent_blocknr = fat_ent_blocknr,
261 .ent_set_ptr = fat32_ent_set_ptr,
262 .ent_bread = fat_ent_bread,
263 .ent_get = fat32_ent_get,
264 .ent_put = fat32_ent_put,
265 .ent_next = fat32_ent_next,
268 static inline void lock_fat(struct msdos_sb_info *sbi)
270 down(&sbi->fat_lock);
273 static inline void unlock_fat(struct msdos_sb_info *sbi)
278 void fat_ent_access_init(struct super_block *sb)
280 struct msdos_sb_info *sbi = MSDOS_SB(sb);
282 init_MUTEX(&sbi->fat_lock);
284 switch (sbi->fat_bits) {
286 sbi->fatent_shift = 2;
287 sbi->fatent_ops = &fat32_ops;
290 sbi->fatent_shift = 1;
291 sbi->fatent_ops = &fat16_ops;
294 sbi->fatent_shift = -1;
295 sbi->fatent_ops = &fat12_ops;
300 static inline int fat_ent_update_ptr(struct super_block *sb,
301 struct fat_entry *fatent,
302 int offset, sector_t blocknr)
304 struct msdos_sb_info *sbi = MSDOS_SB(sb);
305 struct fatent_operations *ops = sbi->fatent_ops;
306 struct buffer_head **bhs = fatent->bhs;
308 /* Is this fatent's blocks including this entry? */
309 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
311 /* Does this entry need the next block? */
312 if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
313 if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
316 ops->ent_set_ptr(fatent, offset);
320 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
322 struct super_block *sb = inode->i_sb;
323 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
324 struct fatent_operations *ops = sbi->fatent_ops;
328 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
329 fatent_brelse(fatent);
330 fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
334 fatent_set_entry(fatent, entry);
335 ops->ent_blocknr(sb, entry, &offset, &blocknr);
337 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
338 fatent_brelse(fatent);
339 err = ops->ent_bread(sb, fatent, offset, blocknr);
343 return ops->ent_get(fatent);
346 /* FIXME: We can write the blocks as more big chunk. */
347 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
350 struct msdos_sb_info *sbi = MSDOS_SB(sb);
351 struct buffer_head *c_bh;
355 for (copy = 1; copy < sbi->fats; copy++) {
356 sector_t backup_fat = sbi->fat_length * copy;
358 for (n = 0; n < nr_bhs; n++) {
359 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
364 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
365 set_buffer_uptodate(c_bh);
366 mark_buffer_dirty(c_bh);
367 if (sb->s_flags & MS_SYNCHRONOUS)
368 err = sync_dirty_buffer(c_bh);
378 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
381 struct super_block *sb = inode->i_sb;
382 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
385 ops->ent_put(fatent, new);
387 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
391 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
394 static inline int fat_ent_next(struct msdos_sb_info *sbi,
395 struct fat_entry *fatent)
397 if (sbi->fatent_ops->ent_next(fatent)) {
398 if (fatent->entry < sbi->max_cluster)
404 static inline int fat_ent_read_block(struct super_block *sb,
405 struct fat_entry *fatent)
407 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
411 fatent_brelse(fatent);
412 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
413 return ops->ent_bread(sb, fatent, offset, blocknr);
416 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
417 struct fat_entry *fatent)
421 for (n = 0; n < fatent->nr_bhs; n++) {
422 for (i = 0; i < *nr_bhs; i++) {
423 if (fatent->bhs[n] == bhs[i])
427 get_bh(fatent->bhs[n]);
428 bhs[i] = fatent->bhs[n];
434 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
436 struct super_block *sb = inode->i_sb;
437 struct msdos_sb_info *sbi = MSDOS_SB(sb);
438 struct fatent_operations *ops = sbi->fatent_ops;
439 struct fat_entry fatent, prev_ent;
440 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
441 int i, count, err, nr_bhs, idx_clus;
443 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
446 if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
451 err = nr_bhs = idx_clus = 0;
452 count = FAT_START_ENT;
453 fatent_init(&prev_ent);
454 fatent_init(&fatent);
455 fatent_set_entry(&fatent, sbi->prev_free + 1);
456 while (count < sbi->max_cluster) {
457 if (fatent.entry >= sbi->max_cluster)
458 fatent.entry = FAT_START_ENT;
459 fatent_set_entry(&fatent, fatent.entry);
460 err = fat_ent_read_block(sb, &fatent);
464 /* Find the free entries in a block */
466 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
467 int entry = fatent.entry;
469 /* make the cluster chain */
470 ops->ent_put(&fatent, FAT_ENT_EOF);
472 ops->ent_put(&prev_ent, entry);
474 fat_collect_bhs(bhs, &nr_bhs, &fatent);
476 sbi->prev_free = entry;
477 if (sbi->free_clusters != -1)
478 sbi->free_clusters--;
481 cluster[idx_clus] = entry;
483 if (idx_clus == nr_cluster)
487 * fat_collect_bhs() gets ref-count of bhs,
488 * so we can still use the prev_ent.
493 if (count == sbi->max_cluster)
495 } while (fat_ent_next(sbi, &fatent));
498 /* Couldn't allocate the free entries */
499 sbi->free_clusters = 0;
505 fatent_brelse(&fatent);
507 if (inode_needs_sync(inode))
508 err = fat_sync_bhs(bhs, nr_bhs);
510 err = fat_mirror_bhs(sb, bhs, nr_bhs);
512 for (i = 0; i < nr_bhs; i++)
516 fat_free_clusters(inode, cluster[0]);
521 int fat_free_clusters(struct inode *inode, int cluster)
523 struct super_block *sb = inode->i_sb;
524 struct msdos_sb_info *sbi = MSDOS_SB(sb);
525 struct fatent_operations *ops = sbi->fatent_ops;
526 struct fat_entry fatent;
527 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
531 fatent_init(&fatent);
534 cluster = fat_ent_read(inode, &fatent, cluster);
538 } else if (cluster == FAT_ENT_FREE) {
539 fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
545 ops->ent_put(&fatent, FAT_ENT_FREE);
546 if (sbi->free_clusters != -1) {
547 sbi->free_clusters++;
551 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
552 if (sb->s_flags & MS_SYNCHRONOUS) {
553 err = fat_sync_bhs(bhs, nr_bhs);
557 err = fat_mirror_bhs(sb, bhs, nr_bhs);
560 for (i = 0; i < nr_bhs; i++)
564 fat_collect_bhs(bhs, &nr_bhs, &fatent);
565 } while (cluster != FAT_ENT_EOF);
567 if (sb->s_flags & MS_SYNCHRONOUS) {
568 err = fat_sync_bhs(bhs, nr_bhs);
572 err = fat_mirror_bhs(sb, bhs, nr_bhs);
574 fatent_brelse(&fatent);
575 for (i = 0; i < nr_bhs; i++)
579 fat_clusters_flush(sb);
584 EXPORT_SYMBOL_GPL(fat_free_clusters);
586 int fat_count_free_clusters(struct super_block *sb)
588 struct msdos_sb_info *sbi = MSDOS_SB(sb);
589 struct fatent_operations *ops = sbi->fatent_ops;
590 struct fat_entry fatent;
594 if (sbi->free_clusters != -1)
598 fatent_init(&fatent);
599 fatent_set_entry(&fatent, FAT_START_ENT);
600 while (fatent.entry < sbi->max_cluster) {
601 err = fat_ent_read_block(sb, &fatent);
606 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
608 } while (fat_ent_next(sbi, &fatent));
610 sbi->free_clusters = free;
612 fatent_brelse(&fatent);