2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
6 #include <linux/blkdev.h>
9 struct fatent_operations {
10 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
11 void (*ent_set_ptr)(struct fat_entry *, int);
12 int (*ent_bread)(struct super_block *, struct fat_entry *,
14 int (*ent_get)(struct fat_entry *);
15 void (*ent_put)(struct fat_entry *, int);
16 int (*ent_next)(struct fat_entry *);
19 static DEFINE_SPINLOCK(fat12_entry_lock);
21 static void fat12_ent_blocknr(struct super_block *sb, int entry,
22 int *offset, sector_t *blocknr)
24 struct msdos_sb_info *sbi = MSDOS_SB(sb);
25 int bytes = entry + (entry >> 1);
26 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
27 *offset = bytes & (sb->s_blocksize - 1);
28 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
31 static void fat_ent_blocknr(struct super_block *sb, int entry,
32 int *offset, sector_t *blocknr)
34 struct msdos_sb_info *sbi = MSDOS_SB(sb);
35 int bytes = (entry << sbi->fatent_shift);
36 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
37 *offset = bytes & (sb->s_blocksize - 1);
38 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
41 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
43 struct buffer_head **bhs = fatent->bhs;
44 if (fatent->nr_bhs == 1) {
45 WARN_ON(offset >= (bhs[0]->b_size - 1));
46 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
47 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
49 WARN_ON(offset != (bhs[0]->b_size - 1));
50 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
51 fatent->u.ent12_p[1] = bhs[1]->b_data;
55 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
57 WARN_ON(offset & (2 - 1));
58 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
61 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
63 WARN_ON(offset & (4 - 1));
64 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
67 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
68 int offset, sector_t blocknr)
70 struct buffer_head **bhs = fatent->bhs;
72 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
73 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
75 bhs[0] = sb_bread(sb, blocknr);
79 if ((offset + 1) < sb->s_blocksize)
82 /* This entry is block boundary, it needs the next block */
84 bhs[1] = sb_bread(sb, blocknr);
89 fat12_ent_set_ptr(fatent, offset);
95 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
99 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
100 int offset, sector_t blocknr)
102 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
104 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
105 fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
106 fatent->bhs[0] = sb_bread(sb, blocknr);
107 if (!fatent->bhs[0]) {
108 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
113 ops->ent_set_ptr(fatent, offset);
117 static int fat12_ent_get(struct fat_entry *fatent)
119 u8 **ent12_p = fatent->u.ent12_p;
122 spin_lock(&fat12_entry_lock);
123 if (fatent->entry & 1)
124 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
126 next = (*ent12_p[1] << 8) | *ent12_p[0];
127 spin_unlock(&fat12_entry_lock);
130 if (next >= BAD_FAT12)
135 static int fat16_ent_get(struct fat_entry *fatent)
137 int next = le16_to_cpu(*fatent->u.ent16_p);
138 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
139 if (next >= BAD_FAT16)
144 static int fat32_ent_get(struct fat_entry *fatent)
146 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
147 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
148 if (next >= BAD_FAT32)
153 static void fat12_ent_put(struct fat_entry *fatent, int new)
155 u8 **ent12_p = fatent->u.ent12_p;
157 if (new == FAT_ENT_EOF)
160 spin_lock(&fat12_entry_lock);
161 if (fatent->entry & 1) {
162 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
163 *ent12_p[1] = new >> 4;
165 *ent12_p[0] = new & 0xff;
166 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
168 spin_unlock(&fat12_entry_lock);
170 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
171 if (fatent->nr_bhs == 2)
172 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode);
175 static void fat16_ent_put(struct fat_entry *fatent, int new)
177 if (new == FAT_ENT_EOF)
180 *fatent->u.ent16_p = cpu_to_le16(new);
181 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
184 static void fat32_ent_put(struct fat_entry *fatent, int new)
186 WARN_ON(new & 0xf0000000);
187 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
188 *fatent->u.ent32_p = cpu_to_le32(new);
189 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
192 static int fat12_ent_next(struct fat_entry *fatent)
194 u8 **ent12_p = fatent->u.ent12_p;
195 struct buffer_head **bhs = fatent->bhs;
196 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
199 if (fatent->nr_bhs == 1) {
200 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data +
201 (bhs[0]->b_size - 2)));
202 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data +
203 (bhs[0]->b_size - 1)));
204 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
205 ent12_p[0] = nextp - 1;
210 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data +
211 (bhs[0]->b_size - 1)));
212 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
213 ent12_p[0] = nextp - 1;
225 static int fat16_ent_next(struct fat_entry *fatent)
227 const struct buffer_head *bh = fatent->bhs[0];
229 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
233 fatent->u.ent16_p = NULL;
237 static int fat32_ent_next(struct fat_entry *fatent)
239 const struct buffer_head *bh = fatent->bhs[0];
241 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
245 fatent->u.ent32_p = NULL;
249 static struct fatent_operations fat12_ops = {
250 .ent_blocknr = fat12_ent_blocknr,
251 .ent_set_ptr = fat12_ent_set_ptr,
252 .ent_bread = fat12_ent_bread,
253 .ent_get = fat12_ent_get,
254 .ent_put = fat12_ent_put,
255 .ent_next = fat12_ent_next,
258 static struct fatent_operations fat16_ops = {
259 .ent_blocknr = fat_ent_blocknr,
260 .ent_set_ptr = fat16_ent_set_ptr,
261 .ent_bread = fat_ent_bread,
262 .ent_get = fat16_ent_get,
263 .ent_put = fat16_ent_put,
264 .ent_next = fat16_ent_next,
267 static struct fatent_operations fat32_ops = {
268 .ent_blocknr = fat_ent_blocknr,
269 .ent_set_ptr = fat32_ent_set_ptr,
270 .ent_bread = fat_ent_bread,
271 .ent_get = fat32_ent_get,
272 .ent_put = fat32_ent_put,
273 .ent_next = fat32_ent_next,
276 static inline void lock_fat(struct msdos_sb_info *sbi)
278 mutex_lock(&sbi->fat_lock);
281 static inline void unlock_fat(struct msdos_sb_info *sbi)
283 mutex_unlock(&sbi->fat_lock);
286 void fat_ent_access_init(struct super_block *sb)
288 struct msdos_sb_info *sbi = MSDOS_SB(sb);
290 mutex_init(&sbi->fat_lock);
292 switch (sbi->fat_bits) {
294 sbi->fatent_shift = 2;
295 sbi->fatent_ops = &fat32_ops;
298 sbi->fatent_shift = 1;
299 sbi->fatent_ops = &fat16_ops;
302 sbi->fatent_shift = -1;
303 sbi->fatent_ops = &fat12_ops;
308 static void mark_fsinfo_dirty(struct super_block *sb)
310 struct msdos_sb_info *sbi = MSDOS_SB(sb);
312 if (sb->s_flags & MS_RDONLY || sbi->fat_bits != 32)
315 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
318 static inline int fat_ent_update_ptr(struct super_block *sb,
319 struct fat_entry *fatent,
320 int offset, sector_t blocknr)
322 struct msdos_sb_info *sbi = MSDOS_SB(sb);
323 struct fatent_operations *ops = sbi->fatent_ops;
324 struct buffer_head **bhs = fatent->bhs;
326 /* Is this fatent's blocks including this entry? */
327 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
329 if (sbi->fat_bits == 12) {
330 if ((offset + 1) < sb->s_blocksize) {
331 /* This entry is on bhs[0]. */
332 if (fatent->nr_bhs == 2) {
337 /* This entry needs the next block. */
338 if (fatent->nr_bhs != 2)
340 if (bhs[1]->b_blocknr != (blocknr + 1))
344 ops->ent_set_ptr(fatent, offset);
348 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
350 struct super_block *sb = inode->i_sb;
351 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
352 struct fatent_operations *ops = sbi->fatent_ops;
356 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
357 fatent_brelse(fatent);
358 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
362 fatent_set_entry(fatent, entry);
363 ops->ent_blocknr(sb, entry, &offset, &blocknr);
365 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
366 fatent_brelse(fatent);
367 err = ops->ent_bread(sb, fatent, offset, blocknr);
371 return ops->ent_get(fatent);
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,
378 struct msdos_sb_info *sbi = MSDOS_SB(sb);
379 struct buffer_head *c_bh;
383 for (copy = 1; copy < sbi->fats; copy++) {
384 sector_t backup_fat = sbi->fat_length * copy;
386 for (n = 0; n < nr_bhs; n++) {
387 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
392 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
393 set_buffer_uptodate(c_bh);
394 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
395 if (sb->s_flags & MS_SYNCHRONOUS)
396 err = sync_dirty_buffer(c_bh);
406 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
409 struct super_block *sb = inode->i_sb;
410 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
413 ops->ent_put(fatent, new);
415 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
419 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
422 static inline int fat_ent_next(struct msdos_sb_info *sbi,
423 struct fat_entry *fatent)
425 if (sbi->fatent_ops->ent_next(fatent)) {
426 if (fatent->entry < sbi->max_cluster)
432 static inline int fat_ent_read_block(struct super_block *sb,
433 struct fat_entry *fatent)
435 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
439 fatent_brelse(fatent);
440 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
441 return ops->ent_bread(sb, fatent, offset, blocknr);
444 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
445 struct fat_entry *fatent)
449 for (n = 0; n < fatent->nr_bhs; n++) {
450 for (i = 0; i < *nr_bhs; i++) {
451 if (fatent->bhs[n] == bhs[i])
455 get_bh(fatent->bhs[n]);
456 bhs[i] = fatent->bhs[n];
462 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
464 struct super_block *sb = inode->i_sb;
465 struct msdos_sb_info *sbi = MSDOS_SB(sb);
466 struct fatent_operations *ops = sbi->fatent_ops;
467 struct fat_entry fatent, prev_ent;
468 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
469 int i, count, err, nr_bhs, idx_clus;
471 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
474 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
475 sbi->free_clusters < nr_cluster) {
480 err = nr_bhs = idx_clus = 0;
481 count = FAT_START_ENT;
482 fatent_init(&prev_ent);
483 fatent_init(&fatent);
484 fatent_set_entry(&fatent, sbi->prev_free + 1);
485 while (count < sbi->max_cluster) {
486 if (fatent.entry >= sbi->max_cluster)
487 fatent.entry = FAT_START_ENT;
488 fatent_set_entry(&fatent, fatent.entry);
489 err = fat_ent_read_block(sb, &fatent);
493 /* Find the free entries in a block */
495 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
496 int entry = fatent.entry;
498 /* make the cluster chain */
499 ops->ent_put(&fatent, FAT_ENT_EOF);
501 ops->ent_put(&prev_ent, entry);
503 fat_collect_bhs(bhs, &nr_bhs, &fatent);
505 sbi->prev_free = entry;
506 if (sbi->free_clusters != -1)
507 sbi->free_clusters--;
509 cluster[idx_clus] = entry;
511 if (idx_clus == nr_cluster)
515 * fat_collect_bhs() gets ref-count of bhs,
516 * so we can still use the prev_ent.
521 if (count == sbi->max_cluster)
523 } while (fat_ent_next(sbi, &fatent));
526 /* Couldn't allocate the free entries */
527 sbi->free_clusters = 0;
528 sbi->free_clus_valid = 1;
533 mark_fsinfo_dirty(sb);
534 fatent_brelse(&fatent);
536 if (inode_needs_sync(inode))
537 err = fat_sync_bhs(bhs, nr_bhs);
539 err = fat_mirror_bhs(sb, bhs, nr_bhs);
541 for (i = 0; i < nr_bhs; i++)
545 fat_free_clusters(inode, cluster[0]);
550 int fat_free_clusters(struct inode *inode, int cluster)
552 struct super_block *sb = inode->i_sb;
553 struct msdos_sb_info *sbi = MSDOS_SB(sb);
554 struct fatent_operations *ops = sbi->fatent_ops;
555 struct fat_entry fatent;
556 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
558 int first_cl = cluster, dirty_fsinfo = 0;
561 fatent_init(&fatent);
564 cluster = fat_ent_read(inode, &fatent, cluster);
568 } else if (cluster == FAT_ENT_FREE) {
569 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
575 if (sbi->options.discard) {
577 * Issue discard for the sectors we no longer
578 * care about, batching contiguous clusters
581 if (cluster != fatent.entry + 1) {
582 int nr_clus = fatent.entry - first_cl + 1;
585 fat_clus_to_blknr(sbi, first_cl),
586 nr_clus * sbi->sec_per_clus,
593 ops->ent_put(&fatent, FAT_ENT_FREE);
594 if (sbi->free_clusters != -1) {
595 sbi->free_clusters++;
599 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
600 if (sb->s_flags & MS_SYNCHRONOUS) {
601 err = fat_sync_bhs(bhs, nr_bhs);
605 err = fat_mirror_bhs(sb, bhs, nr_bhs);
608 for (i = 0; i < nr_bhs; i++)
612 fat_collect_bhs(bhs, &nr_bhs, &fatent);
613 } while (cluster != FAT_ENT_EOF);
615 if (sb->s_flags & MS_SYNCHRONOUS) {
616 err = fat_sync_bhs(bhs, nr_bhs);
620 err = fat_mirror_bhs(sb, bhs, nr_bhs);
622 fatent_brelse(&fatent);
623 for (i = 0; i < nr_bhs; i++)
627 mark_fsinfo_dirty(sb);
631 EXPORT_SYMBOL_GPL(fat_free_clusters);
633 /* 128kb is the whole sectors for FAT12 and FAT16 */
634 #define FAT_READA_SIZE (128 * 1024)
636 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
637 unsigned long reada_blocks)
639 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
643 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
645 for (i = 0; i < reada_blocks; i++)
646 sb_breadahead(sb, blocknr + i);
649 int fat_count_free_clusters(struct super_block *sb)
651 struct msdos_sb_info *sbi = MSDOS_SB(sb);
652 struct fatent_operations *ops = sbi->fatent_ops;
653 struct fat_entry fatent;
654 unsigned long reada_blocks, reada_mask, cur_block;
658 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
661 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
662 reada_mask = reada_blocks - 1;
666 fatent_init(&fatent);
667 fatent_set_entry(&fatent, FAT_START_ENT);
668 while (fatent.entry < sbi->max_cluster) {
669 /* readahead of fat blocks */
670 if ((cur_block & reada_mask) == 0) {
671 unsigned long rest = sbi->fat_length - cur_block;
672 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
676 err = fat_ent_read_block(sb, &fatent);
681 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
683 } while (fat_ent_next(sbi, &fatent));
685 sbi->free_clusters = free;
686 sbi->free_clus_valid = 1;
687 mark_fsinfo_dirty(sb);
688 fatent_brelse(&fatent);