2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
6 #include <linux/module.h>
8 #include <linux/msdos_fs.h>
9 #include <linux/blkdev.h>
12 struct 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 *,
17 int (*ent_get)(struct fat_entry *);
18 void (*ent_put)(struct fat_entry *, int);
19 int (*ent_next)(struct fat_entry *);
22 static DEFINE_SPINLOCK(fat12_entry_lock);
24 static void fat12_ent_blocknr(struct super_block *sb, int entry,
25 int *offset, sector_t *blocknr)
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);
34 static void fat_ent_blocknr(struct super_block *sb, int entry,
35 int *offset, sector_t *blocknr)
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);
44 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
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);
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;
58 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
60 WARN_ON(offset & (2 - 1));
61 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
64 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
66 WARN_ON(offset & (4 - 1));
67 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
70 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
71 int offset, sector_t blocknr)
73 struct buffer_head **bhs = fatent->bhs;
75 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
76 bhs[0] = sb_bread(sb, blocknr);
80 if ((offset + 1) < sb->s_blocksize)
83 /* This entry is block boundary, it needs the next block */
85 bhs[1] = sb_bread(sb, blocknr);
90 fat12_ent_set_ptr(fatent, offset);
96 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
97 (unsigned long long)blocknr);
101 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
102 int offset, sector_t blocknr)
104 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
106 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
107 fatent->bhs[0] = sb_bread(sb, blocknr);
108 if (!fatent->bhs[0]) {
109 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
110 (unsigned long long)blocknr);
114 ops->ent_set_ptr(fatent, offset);
118 static int fat12_ent_get(struct fat_entry *fatent)
120 u8 **ent12_p = fatent->u.ent12_p;
123 spin_lock(&fat12_entry_lock);
124 if (fatent->entry & 1)
125 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
127 next = (*ent12_p[1] << 8) | *ent12_p[0];
128 spin_unlock(&fat12_entry_lock);
131 if (next >= BAD_FAT12)
136 static int fat16_ent_get(struct fat_entry *fatent)
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)
145 static int fat32_ent_get(struct fat_entry *fatent)
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)
154 static void fat12_ent_put(struct fat_entry *fatent, int new)
156 u8 **ent12_p = fatent->u.ent12_p;
158 if (new == FAT_ENT_EOF)
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;
166 *ent12_p[0] = new & 0xff;
167 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
169 spin_unlock(&fat12_entry_lock);
171 mark_buffer_dirty(fatent->bhs[0]);
172 if (fatent->nr_bhs == 2)
173 mark_buffer_dirty(fatent->bhs[1]);
176 static void fat16_ent_put(struct fat_entry *fatent, int new)
178 if (new == FAT_ENT_EOF)
181 *fatent->u.ent16_p = cpu_to_le16(new);
182 mark_buffer_dirty(fatent->bhs[0]);
185 static void fat32_ent_put(struct fat_entry *fatent, int new)
187 if (new == FAT_ENT_EOF)
190 WARN_ON(new & 0xf0000000);
191 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
192 *fatent->u.ent32_p = cpu_to_le32(new);
193 mark_buffer_dirty(fatent->bhs[0]);
196 static int fat12_ent_next(struct fat_entry *fatent)
198 u8 **ent12_p = fatent->u.ent12_p;
199 struct buffer_head **bhs = fatent->bhs;
200 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
203 if (fatent->nr_bhs == 1) {
204 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
205 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
206 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
207 ent12_p[0] = nextp - 1;
212 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
213 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
214 ent12_p[0] = nextp - 1;
226 static int fat16_ent_next(struct fat_entry *fatent)
228 const struct buffer_head *bh = fatent->bhs[0];
230 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
234 fatent->u.ent16_p = NULL;
238 static int fat32_ent_next(struct fat_entry *fatent)
240 const struct buffer_head *bh = fatent->bhs[0];
242 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
246 fatent->u.ent32_p = NULL;
250 static 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,
259 static 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,
268 static 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,
277 static inline void lock_fat(struct msdos_sb_info *sbi)
279 mutex_lock(&sbi->fat_lock);
282 static inline void unlock_fat(struct msdos_sb_info *sbi)
284 mutex_unlock(&sbi->fat_lock);
287 void fat_ent_access_init(struct super_block *sb)
289 struct msdos_sb_info *sbi = MSDOS_SB(sb);
291 mutex_init(&sbi->fat_lock);
293 switch (sbi->fat_bits) {
295 sbi->fatent_shift = 2;
296 sbi->fatent_ops = &fat32_ops;
299 sbi->fatent_shift = 1;
300 sbi->fatent_ops = &fat16_ops;
303 sbi->fatent_shift = -1;
304 sbi->fatent_ops = &fat12_ops;
309 static inline int fat_ent_update_ptr(struct super_block *sb,
310 struct fat_entry *fatent,
311 int offset, sector_t blocknr)
313 struct msdos_sb_info *sbi = MSDOS_SB(sb);
314 struct fatent_operations *ops = sbi->fatent_ops;
315 struct buffer_head **bhs = fatent->bhs;
317 /* Is this fatent's blocks including this entry? */
318 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
320 /* Does this entry need the next block? */
321 if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
322 if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
325 ops->ent_set_ptr(fatent, offset);
329 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
331 struct super_block *sb = inode->i_sb;
332 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
333 struct fatent_operations *ops = sbi->fatent_ops;
337 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
338 fatent_brelse(fatent);
339 fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
343 fatent_set_entry(fatent, entry);
344 ops->ent_blocknr(sb, entry, &offset, &blocknr);
346 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
347 fatent_brelse(fatent);
348 err = ops->ent_bread(sb, fatent, offset, blocknr);
352 return ops->ent_get(fatent);
355 /* FIXME: We can write the blocks as more big chunk. */
356 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
359 struct msdos_sb_info *sbi = MSDOS_SB(sb);
360 struct buffer_head *c_bh;
364 for (copy = 1; copy < sbi->fats; copy++) {
365 sector_t backup_fat = sbi->fat_length * copy;
367 for (n = 0; n < nr_bhs; n++) {
368 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
373 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
374 set_buffer_uptodate(c_bh);
375 mark_buffer_dirty(c_bh);
376 if (sb->s_flags & MS_SYNCHRONOUS)
377 err = sync_dirty_buffer(c_bh);
387 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
390 struct super_block *sb = inode->i_sb;
391 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
394 ops->ent_put(fatent, new);
396 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
400 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
403 static inline int fat_ent_next(struct msdos_sb_info *sbi,
404 struct fat_entry *fatent)
406 if (sbi->fatent_ops->ent_next(fatent)) {
407 if (fatent->entry < sbi->max_cluster)
413 static inline int fat_ent_read_block(struct super_block *sb,
414 struct fat_entry *fatent)
416 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
420 fatent_brelse(fatent);
421 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
422 return ops->ent_bread(sb, fatent, offset, blocknr);
425 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
426 struct fat_entry *fatent)
430 for (n = 0; n < fatent->nr_bhs; n++) {
431 for (i = 0; i < *nr_bhs; i++) {
432 if (fatent->bhs[n] == bhs[i])
436 get_bh(fatent->bhs[n]);
437 bhs[i] = fatent->bhs[n];
443 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
445 struct super_block *sb = inode->i_sb;
446 struct msdos_sb_info *sbi = MSDOS_SB(sb);
447 struct fatent_operations *ops = sbi->fatent_ops;
448 struct fat_entry fatent, prev_ent;
449 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
450 int i, count, err, nr_bhs, idx_clus;
452 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
455 if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
456 sbi->free_clusters < nr_cluster) {
461 err = nr_bhs = idx_clus = 0;
462 count = FAT_START_ENT;
463 fatent_init(&prev_ent);
464 fatent_init(&fatent);
465 fatent_set_entry(&fatent, sbi->prev_free + 1);
466 while (count < sbi->max_cluster) {
467 if (fatent.entry >= sbi->max_cluster)
468 fatent.entry = FAT_START_ENT;
469 fatent_set_entry(&fatent, fatent.entry);
470 err = fat_ent_read_block(sb, &fatent);
474 /* Find the free entries in a block */
476 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
477 int entry = fatent.entry;
479 /* make the cluster chain */
480 ops->ent_put(&fatent, FAT_ENT_EOF);
482 ops->ent_put(&prev_ent, entry);
484 fat_collect_bhs(bhs, &nr_bhs, &fatent);
486 sbi->prev_free = entry;
487 if (sbi->free_clusters != -1)
488 sbi->free_clusters--;
491 cluster[idx_clus] = entry;
493 if (idx_clus == nr_cluster)
497 * fat_collect_bhs() gets ref-count of bhs,
498 * so we can still use the prev_ent.
503 if (count == sbi->max_cluster)
505 } while (fat_ent_next(sbi, &fatent));
508 /* Couldn't allocate the free entries */
509 sbi->free_clusters = 0;
510 sbi->free_clus_valid = 1;
516 fatent_brelse(&fatent);
518 if (inode_needs_sync(inode))
519 err = fat_sync_bhs(bhs, nr_bhs);
521 err = fat_mirror_bhs(sb, bhs, nr_bhs);
523 for (i = 0; i < nr_bhs; i++)
527 fat_free_clusters(inode, cluster[0]);
532 int fat_free_clusters(struct inode *inode, int cluster)
534 struct super_block *sb = inode->i_sb;
535 struct msdos_sb_info *sbi = MSDOS_SB(sb);
536 struct fatent_operations *ops = sbi->fatent_ops;
537 struct fat_entry fatent;
538 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
540 int first_cl = cluster;
543 fatent_init(&fatent);
546 cluster = fat_ent_read(inode, &fatent, cluster);
550 } else if (cluster == FAT_ENT_FREE) {
551 fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
558 * Issue discard for the sectors we no longer care about,
559 * batching contiguous clusters into one request
561 if (cluster != fatent.entry + 1) {
562 int nr_clus = fatent.entry - first_cl + 1;
564 sb_issue_discard(sb, fat_clus_to_blknr(sbi, first_cl),
565 nr_clus * sbi->sec_per_clus);
569 ops->ent_put(&fatent, FAT_ENT_FREE);
570 if (sbi->free_clusters != -1) {
571 sbi->free_clusters++;
575 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
576 if (sb->s_flags & MS_SYNCHRONOUS) {
577 err = fat_sync_bhs(bhs, nr_bhs);
581 err = fat_mirror_bhs(sb, bhs, nr_bhs);
584 for (i = 0; i < nr_bhs; i++)
588 fat_collect_bhs(bhs, &nr_bhs, &fatent);
589 } while (cluster != FAT_ENT_EOF);
591 if (sb->s_flags & MS_SYNCHRONOUS) {
592 err = fat_sync_bhs(bhs, nr_bhs);
596 err = fat_mirror_bhs(sb, bhs, nr_bhs);
598 fatent_brelse(&fatent);
599 for (i = 0; i < nr_bhs; i++)
606 EXPORT_SYMBOL_GPL(fat_free_clusters);
608 /* 128kb is the whole sectors for FAT12 and FAT16 */
609 #define FAT_READA_SIZE (128 * 1024)
611 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
612 unsigned long reada_blocks)
614 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
618 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
620 for (i = 0; i < reada_blocks; i++)
621 sb_breadahead(sb, blocknr + i);
624 int fat_count_free_clusters(struct super_block *sb)
626 struct msdos_sb_info *sbi = MSDOS_SB(sb);
627 struct fatent_operations *ops = sbi->fatent_ops;
628 struct fat_entry fatent;
629 unsigned long reada_blocks, reada_mask, cur_block;
633 if (sbi->free_clusters != -1 && sbi->free_clus_valid)
636 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
637 reada_mask = reada_blocks - 1;
641 fatent_init(&fatent);
642 fatent_set_entry(&fatent, FAT_START_ENT);
643 while (fatent.entry < sbi->max_cluster) {
644 /* readahead of fat blocks */
645 if ((cur_block & reada_mask) == 0) {
646 unsigned long rest = sbi->fat_length - cur_block;
647 fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
651 err = fat_ent_read_block(sb, &fatent);
656 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
658 } while (fat_ent_next(sbi, &fatent));
660 sbi->free_clusters = free;
661 sbi->free_clus_valid = 1;
663 fatent_brelse(&fatent);