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 if (sbi
->fat_bits
== 12) {
321 if ((offset
+ 1) < sb
->s_blocksize
) {
322 /* This entry is on bhs[0]. */
323 if (fatent
->nr_bhs
== 2) {
328 /* This entry needs the next block. */
329 if (fatent
->nr_bhs
!= 2)
331 if (bhs
[1]->b_blocknr
!= (blocknr
+ 1))
335 ops
->ent_set_ptr(fatent
, offset
);
339 int fat_ent_read(struct inode
*inode
, struct fat_entry
*fatent
, int entry
)
341 struct super_block
*sb
= inode
->i_sb
;
342 struct msdos_sb_info
*sbi
= MSDOS_SB(inode
->i_sb
);
343 struct fatent_operations
*ops
= sbi
->fatent_ops
;
347 if (entry
< FAT_START_ENT
|| sbi
->max_cluster
<= entry
) {
348 fatent_brelse(fatent
);
349 fat_fs_panic(sb
, "invalid access to FAT (entry 0x%08x)", entry
);
353 fatent_set_entry(fatent
, entry
);
354 ops
->ent_blocknr(sb
, entry
, &offset
, &blocknr
);
356 if (!fat_ent_update_ptr(sb
, fatent
, offset
, blocknr
)) {
357 fatent_brelse(fatent
);
358 err
= ops
->ent_bread(sb
, fatent
, offset
, blocknr
);
362 return ops
->ent_get(fatent
);
365 /* FIXME: We can write the blocks as more big chunk. */
366 static int fat_mirror_bhs(struct super_block
*sb
, struct buffer_head
**bhs
,
369 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
370 struct buffer_head
*c_bh
;
374 for (copy
= 1; copy
< sbi
->fats
; copy
++) {
375 sector_t backup_fat
= sbi
->fat_length
* copy
;
377 for (n
= 0; n
< nr_bhs
; n
++) {
378 c_bh
= sb_getblk(sb
, backup_fat
+ bhs
[n
]->b_blocknr
);
383 memcpy(c_bh
->b_data
, bhs
[n
]->b_data
, sb
->s_blocksize
);
384 set_buffer_uptodate(c_bh
);
385 mark_buffer_dirty(c_bh
);
386 if (sb
->s_flags
& MS_SYNCHRONOUS
)
387 err
= sync_dirty_buffer(c_bh
);
397 int fat_ent_write(struct inode
*inode
, struct fat_entry
*fatent
,
400 struct super_block
*sb
= inode
->i_sb
;
401 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
404 ops
->ent_put(fatent
, new);
406 err
= fat_sync_bhs(fatent
->bhs
, fatent
->nr_bhs
);
410 return fat_mirror_bhs(sb
, fatent
->bhs
, fatent
->nr_bhs
);
413 static inline int fat_ent_next(struct msdos_sb_info
*sbi
,
414 struct fat_entry
*fatent
)
416 if (sbi
->fatent_ops
->ent_next(fatent
)) {
417 if (fatent
->entry
< sbi
->max_cluster
)
423 static inline int fat_ent_read_block(struct super_block
*sb
,
424 struct fat_entry
*fatent
)
426 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
430 fatent_brelse(fatent
);
431 ops
->ent_blocknr(sb
, fatent
->entry
, &offset
, &blocknr
);
432 return ops
->ent_bread(sb
, fatent
, offset
, blocknr
);
435 static void fat_collect_bhs(struct buffer_head
**bhs
, int *nr_bhs
,
436 struct fat_entry
*fatent
)
440 for (n
= 0; n
< fatent
->nr_bhs
; n
++) {
441 for (i
= 0; i
< *nr_bhs
; i
++) {
442 if (fatent
->bhs
[n
] == bhs
[i
])
446 get_bh(fatent
->bhs
[n
]);
447 bhs
[i
] = fatent
->bhs
[n
];
453 int fat_alloc_clusters(struct inode
*inode
, int *cluster
, int nr_cluster
)
455 struct super_block
*sb
= inode
->i_sb
;
456 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
457 struct fatent_operations
*ops
= sbi
->fatent_ops
;
458 struct fat_entry fatent
, prev_ent
;
459 struct buffer_head
*bhs
[MAX_BUF_PER_PAGE
];
460 int i
, count
, err
, nr_bhs
, idx_clus
;
462 BUG_ON(nr_cluster
> (MAX_BUF_PER_PAGE
/ 2)); /* fixed limit */
465 if (sbi
->free_clusters
!= -1 && sbi
->free_clus_valid
&&
466 sbi
->free_clusters
< nr_cluster
) {
471 err
= nr_bhs
= idx_clus
= 0;
472 count
= FAT_START_ENT
;
473 fatent_init(&prev_ent
);
474 fatent_init(&fatent
);
475 fatent_set_entry(&fatent
, sbi
->prev_free
+ 1);
476 while (count
< sbi
->max_cluster
) {
477 if (fatent
.entry
>= sbi
->max_cluster
)
478 fatent
.entry
= FAT_START_ENT
;
479 fatent_set_entry(&fatent
, fatent
.entry
);
480 err
= fat_ent_read_block(sb
, &fatent
);
484 /* Find the free entries in a block */
486 if (ops
->ent_get(&fatent
) == FAT_ENT_FREE
) {
487 int entry
= fatent
.entry
;
489 /* make the cluster chain */
490 ops
->ent_put(&fatent
, FAT_ENT_EOF
);
492 ops
->ent_put(&prev_ent
, entry
);
494 fat_collect_bhs(bhs
, &nr_bhs
, &fatent
);
496 sbi
->prev_free
= entry
;
497 if (sbi
->free_clusters
!= -1)
498 sbi
->free_clusters
--;
501 cluster
[idx_clus
] = entry
;
503 if (idx_clus
== nr_cluster
)
507 * fat_collect_bhs() gets ref-count of bhs,
508 * so we can still use the prev_ent.
513 if (count
== sbi
->max_cluster
)
515 } while (fat_ent_next(sbi
, &fatent
));
518 /* Couldn't allocate the free entries */
519 sbi
->free_clusters
= 0;
520 sbi
->free_clus_valid
= 1;
526 fatent_brelse(&fatent
);
528 if (inode_needs_sync(inode
))
529 err
= fat_sync_bhs(bhs
, nr_bhs
);
531 err
= fat_mirror_bhs(sb
, bhs
, nr_bhs
);
533 for (i
= 0; i
< nr_bhs
; i
++)
537 fat_free_clusters(inode
, cluster
[0]);
542 int fat_free_clusters(struct inode
*inode
, int cluster
)
544 struct super_block
*sb
= inode
->i_sb
;
545 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
546 struct fatent_operations
*ops
= sbi
->fatent_ops
;
547 struct fat_entry fatent
;
548 struct buffer_head
*bhs
[MAX_BUF_PER_PAGE
];
550 int first_cl
= cluster
;
553 fatent_init(&fatent
);
556 cluster
= fat_ent_read(inode
, &fatent
, cluster
);
560 } else if (cluster
== FAT_ENT_FREE
) {
561 fat_fs_panic(sb
, "%s: deleting FAT entry beyond EOF",
568 * Issue discard for the sectors we no longer care about,
569 * batching contiguous clusters into one request
571 if (cluster
!= fatent
.entry
+ 1) {
572 int nr_clus
= fatent
.entry
- first_cl
+ 1;
574 sb_issue_discard(sb
, fat_clus_to_blknr(sbi
, first_cl
),
575 nr_clus
* sbi
->sec_per_clus
);
579 ops
->ent_put(&fatent
, FAT_ENT_FREE
);
580 if (sbi
->free_clusters
!= -1) {
581 sbi
->free_clusters
++;
585 if (nr_bhs
+ fatent
.nr_bhs
> MAX_BUF_PER_PAGE
) {
586 if (sb
->s_flags
& MS_SYNCHRONOUS
) {
587 err
= fat_sync_bhs(bhs
, nr_bhs
);
591 err
= fat_mirror_bhs(sb
, bhs
, nr_bhs
);
594 for (i
= 0; i
< nr_bhs
; i
++)
598 fat_collect_bhs(bhs
, &nr_bhs
, &fatent
);
599 } while (cluster
!= FAT_ENT_EOF
);
601 if (sb
->s_flags
& MS_SYNCHRONOUS
) {
602 err
= fat_sync_bhs(bhs
, nr_bhs
);
606 err
= fat_mirror_bhs(sb
, bhs
, nr_bhs
);
608 fatent_brelse(&fatent
);
609 for (i
= 0; i
< nr_bhs
; i
++)
616 EXPORT_SYMBOL_GPL(fat_free_clusters
);
618 /* 128kb is the whole sectors for FAT12 and FAT16 */
619 #define FAT_READA_SIZE (128 * 1024)
621 static void fat_ent_reada(struct super_block
*sb
, struct fat_entry
*fatent
,
622 unsigned long reada_blocks
)
624 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
628 ops
->ent_blocknr(sb
, fatent
->entry
, &offset
, &blocknr
);
630 for (i
= 0; i
< reada_blocks
; i
++)
631 sb_breadahead(sb
, blocknr
+ i
);
634 int fat_count_free_clusters(struct super_block
*sb
)
636 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
637 struct fatent_operations
*ops
= sbi
->fatent_ops
;
638 struct fat_entry fatent
;
639 unsigned long reada_blocks
, reada_mask
, cur_block
;
643 if (sbi
->free_clusters
!= -1 && sbi
->free_clus_valid
)
646 reada_blocks
= FAT_READA_SIZE
>> sb
->s_blocksize_bits
;
647 reada_mask
= reada_blocks
- 1;
651 fatent_init(&fatent
);
652 fatent_set_entry(&fatent
, FAT_START_ENT
);
653 while (fatent
.entry
< sbi
->max_cluster
) {
654 /* readahead of fat blocks */
655 if ((cur_block
& reada_mask
) == 0) {
656 unsigned long rest
= sbi
->fat_length
- cur_block
;
657 fat_ent_reada(sb
, &fatent
, min(reada_blocks
, rest
));
661 err
= fat_ent_read_block(sb
, &fatent
);
666 if (ops
->ent_get(&fatent
) == FAT_ENT_FREE
)
668 } while (fat_ent_next(sbi
, &fatent
));
670 sbi
->free_clusters
= free
;
671 sbi
->free_clus_valid
= 1;
673 fatent_brelse(&fatent
);