/*
* Copyright (C) 2004, OGAWA Hirofumi
* Released under GPL v2.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
struct fatent_operations {
void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
void (*ent_set_ptr)(struct fat_entry *, int);
int (*ent_bread)(struct super_block *, struct fat_entry *,
int, sector_t);
int (*ent_get)(struct fat_entry *);
void (*ent_put)(struct fat_entry *, int);
int (*ent_next)(struct fat_entry *);
};
static void fat12_ent_blocknr(struct super_block *sb, int entry,
int *offset, sector_t *blocknr)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
int bytes = entry + (entry >> 1);
WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
*offset = bytes & (sb->s_blocksize - 1);
*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
}
static void fat_ent_blocknr(struct super_block *sb, int entry,
int *offset, sector_t *blocknr)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
int bytes = (entry << sbi->fatent_shift);
WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
*offset = bytes & (sb->s_blocksize - 1);
*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
}
static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
{
struct buffer_head **bhs = fatent->bhs;
if (fatent->nr_bhs == 1) {
WARN_ON(offset >= (bhs[0]->b_size - 1));
fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
} else {
WARN_ON(offset != (bhs[0]->b_size - 1));
fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
fatent->u.ent12_p[1] = bhs[1]->b_data;
}
}
static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
{
WARN_ON(offset & (2 - 1));
fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
}
static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
{
WARN_ON(offset & (4 - 1));
fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
}
static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
int offset, sector_t blocknr)
{
struct buffer_head **bhs = fatent->bhs;
WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
bhs[0] = sb_bread(sb, blocknr);
if (!bhs[0])
goto err;
if ((offset + 1) < sb->s_blocksize)
fatent->nr_bhs = 1;
else {
/* This entry is block boundary, it needs the next block */
blocknr++;
bhs[1] = sb_bread(sb, blocknr);
if (!bhs[1])
goto err_brelse;
fatent->nr_bhs = 2;
}
fat12_ent_set_ptr(fatent, offset);
return 0;
err_brelse:
brelse(bhs[0]);
err:
printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
(unsigned long long)blocknr);
return -EIO;
}
static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
int offset, sector_t blocknr)
{
struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
fatent->bhs[0] = sb_bread(sb, blocknr);
if (!fatent->bhs[0]) {
printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
(unsigned long long)blocknr);
return -EIO;
}
fatent->nr_bhs = 1;
ops->ent_set_ptr(fatent, offset);
return 0;
}
static int fat12_ent_get(struct fat_entry *fatent)
{
u8 **ent12_p = fatent->u.ent12_p;
int next;
if (fatent->entry & 1)
next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
else
next = (*ent12_p[1] << 8) | *ent12_p[0];
next &= 0x0fff;
if (next >= BAD_FAT12)
next = FAT_ENT_EOF;
return next;
}
static int fat16_ent_get(struct fat_entry *fatent)
{
int next = le16_to_cpu(*fatent->u.ent16_p);
WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
if (next >= BAD_FAT16)
next = FAT_ENT_EOF;
return next;
}
static int fat32_ent_get(struct fat_entry *fatent)
{
int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
if (next >= BAD_FAT32)
next = FAT_ENT_EOF;
return next;
}
static void fat12_ent_put(struct fat_entry *fatent, int new)
{
u8 **ent12_p = fatent->u.ent12_p;
if (new == FAT_ENT_EOF)
new = EOF_FAT12;
if (fatent->entry & 1) {
*ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
*ent12_p[1] = new >> 4;
} else {
*ent12_p[0] = new & 0xff;
*ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
}
mark_buffer_dirty(fatent->bhs[0]);
if (fatent->nr_bhs == 2)
mark_buffer_dirty(fatent->bhs[1]);
}
static void fat16_ent_put(struct fat_entry *fatent, int new)
{
if (new == FAT_ENT_EOF)
new = EOF_FAT16;
*fatent->u.ent16_p = cpu_to_le16(new);
mark_buffer_dirty(fatent->bhs[0]);
}
static void fat32_ent_put(struct fat_entry *fatent, int new)
{
if (new == FAT_ENT_EOF)
new = EOF_FAT32;
WARN_ON(new & 0xf0000000);
new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
*fatent->u.ent32_p = cpu_to_le32(new);
mark_buffer_dirty(fatent->bhs[0]);
}
static int fat12_ent_next(struct fat_entry *fatent)
{
u8 **ent12_p = fatent->u.ent12_p;
struct buffer_head **bhs = fatent->bhs;
u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
fatent->entry++;
if (fatent->nr_bhs == 1) {
WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
ent12_p[0] = nextp - 1;
ent12_p[1] = nextp;
return 1;
}
} else {
WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
ent12_p[0] = nextp - 1;
ent12_p[1] = nextp;
brelse(bhs[0]);
bhs[0] = bhs[1];
fatent->nr_bhs = 1;
return 1;
}
ent12_p[0] = NULL;
ent12_p[1] = NULL;
return 0;
}
static int fat16_ent_next(struct fat_entry *fatent)
{
const struct buffer_head *bh = fatent->bhs[0];
fatent->entry++;
if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
fatent->u.ent16_p++;
return 1;
}
fatent->u.ent16_p = NULL;
return 0;
}
static int fat32_ent_next(struct fat_entry *fatent)
{
const struct buffer_head *bh = fatent->bhs[0];
fatent->entry++;
if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
fatent->u.ent32_p++;
return 1;
}
fatent->u.ent32_p = NULL;
return 0;
}
static struct fatent_operations fat12_ops = {
.ent_blocknr = fat12_ent_blocknr,
.ent_set_ptr = fat12_ent_set_ptr,
.ent_bread = fat12_ent_bread,
.ent_get = fat12_ent_get,
.ent_put = fat12_ent_put,
.ent_next = fat12_ent_next,
};
static struct fatent_operations fat16_ops = {
.ent_blocknr = fat_ent_blocknr,
.ent_set_ptr = fat16_ent_set_ptr,
.ent_bread = fat_ent_bread,
.ent_get = fat16_ent_get,
.ent_put = fat16_ent_put,
.ent_next = fat16_ent_next,
};
static struct fatent_operations fat32_ops = {
.ent_blocknr = fat_ent_blocknr,
.ent_set_ptr = fat32_ent_set_ptr,
.ent_bread = fat_ent_bread,
.ent_get = fat32_ent_get,
.ent_put = fat32_ent_put,
.ent_next = fat32_ent_next,
};
static inline void lock_fat(struct msdos_sb_info *sbi)
{
down(&sbi->fat_lock);
}
static inline void unlock_fat(struct msdos_sb_info *sbi)
{
up(&sbi->fat_lock);
}
void fat_ent_access_init(struct super_block *sb)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
init_MUTEX(&sbi->fat_lock);
switch (sbi->fat_bits) {
case 32:
sbi->fatent_shift = 2;
sbi->fatent_ops = &fat32_ops;
break;
case 16:
sbi->fatent_shift = 1;
sbi->fatent_ops = &fat16_ops;
break;
case 12:
sbi->fatent_shift = -1;
sbi->fatent_ops = &fat12_ops;
break;
}
}
static inline int fat_ent_update_ptr(struct super_block *sb,
struct fat_entry *fatent,
int offset, sector_t blocknr)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct fatent_operations *ops = sbi->fatent_ops;
struct buffer_head **bhs = fatent->bhs;
/* Is this fatent's blocks including this entry? */
if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
return 0;
/* Does this entry need the next block? */
if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
return 0;
}
ops->ent_set_ptr(fatent, offset);
return 1;
}
int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
struct fatent_operations *ops = sbi->fatent_ops;
int err, offset;
sector_t blocknr;
if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
fatent_brelse(fatent);
fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
return -EIO;
}
fatent_set_entry(fatent, entry);
ops->ent_blocknr(sb, entry, &offset, &blocknr);
if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
fatent_brelse(fatent);
err = ops->ent_bread(sb, fatent, offset, blocknr);
if (err)
return err;
}
return ops->ent_get(fatent);
}
/* FIXME: We can write the blocks as more big chunk. */
static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
int nr_bhs)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct buffer_head *c_bh;
int err, n, copy;
err = 0;
for (copy = 1; copy < sbi->fats; copy++) {
sector_t backup_fat = sbi->fat_length * copy;
for (n = 0; n < nr_bhs; n++) {
c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
if (!c_bh) {
err = -ENOMEM;
goto error;
}
memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
set_buffer_uptodate(c_bh);
mark_buffer_dirty(c_bh);
if (sb->s_flags & MS_SYNCHRONOUS)
err = sync_dirty_buffer(c_bh);
brelse(c_bh);
if (err)
goto error;
}
}
error:
return err;
}
int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
int new, int wait)
{
struct super_block *sb = inode->i_sb;
struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
int err;
ops->ent_put(fatent, new);
if (wait) {
err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
if (err)
return err;
}
return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
}
static inline int fat_ent_next(struct msdos_sb_info *sbi,
struct fat_entry *fatent)
{
if (sbi->fatent_ops->ent_next(fatent)) {
if (fatent->entry < sbi->max_cluster)
return 1;
}
return 0;
}
static inline int fat_ent_read_block(struct super_block *sb,
struct fat_entry *fatent)
{
struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
sector_t blocknr;
int offset;
fatent_brelse(fatent);
ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
return ops->ent_bread(sb, fatent, offset, blocknr);
}
static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
struct fat_entry *fatent)
{
int n, i;
for (n = 0; n < fatent->nr_bhs; n++) {
for (i = 0; i < *nr_bhs; i++) {
if (fatent->bhs[n] == bhs[i])
break;
}
if (i == *nr_bhs) {
get_bh(fatent->bhs[n]);
bhs[i] = fatent->bhs[n];
(*nr_bhs)++;
}
}
}
int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct fatent_operations *ops = sbi->fatent_ops;
struct fat_entry fatent, prev_ent;
struct buffer_head *bhs[MAX_BUF_PER_PAGE];
int i, count, err, nr_bhs, idx_clus;
BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
lock_fat(sbi);
if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
unlock_fat(sbi);
return -ENOSPC;
}
err = nr_bhs = idx_clus = 0;
count = FAT_START_ENT;
fatent_init(&prev_ent);
fatent_init(&fatent);
fatent_set_entry(&fatent, sbi->prev_free + 1);
while (count < sbi->max_cluster) {
if (fatent.entry >= sbi->max_cluster)
fatent.entry = FAT_START_ENT;
fatent_set_entry(&fatent, fatent.entry);
err = fat_ent_read_block(sb, &fatent);
if (err)
goto out;
/* Find the free entries in a block */
do {
if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
int entry = fatent.entry;
/* make the cluster chain */
ops->ent_put(&fatent, FAT_ENT_EOF);
if (prev_ent.nr_bhs)
ops->ent_put(&prev_ent, entry);
fat_collect_bhs(bhs, &nr_bhs, &fatent);
sbi->prev_free = entry;
if (sbi->free_clusters != -1)
sbi->free_clusters--;
sb->s_dirt = 1;
cluster[idx_clus] = entry;
idx_clus++;
if (idx_clus == nr_cluster)
goto out;
/*
* fat_collect_bhs() gets ref-count of bhs,
* so we can still use the prev_ent.
*/
prev_ent = fatent;
}
count++;
if (count == sbi->max_cluster)
break;
} while (fat_ent_next(sbi, &fatent));
}
/* Couldn't allocate the free entries */
sbi->free_clusters = 0;
sb->s_dirt = 1;
err = -ENOSPC;
out:
unlock_fat(sbi);
fatent_brelse(&fatent);
if (!err) {
if (inode_needs_sync(inode))
err = fat_sync_bhs(bhs, nr_bhs);
if (!err)
err = fat_mirror_bhs(sb, bhs, nr_bhs);
}
for (i = 0; i < nr_bhs; i++)
brelse(bhs[i]);
if (err && idx_clus)
fat_free_clusters(inode, cluster[0]);
return err;
}
int fat_free_clusters(struct inode *inode, int cluster)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct fatent_operations *ops = sbi->fatent_ops;
struct fat_entry fatent;
struct buffer_head *bhs[MAX_BUF_PER_PAGE];
int i, err, nr_bhs;
nr_bhs = 0;
fatent_init(&fatent);
lock_fat(sbi);
do {
cluster = fat_ent_read(inode, &fatent, cluster);
if (cluster < 0) {
err = cluster;
goto error;
} else if (cluster == FAT_ENT_FREE) {
fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
__FUNCTION__);
err = -EIO;
goto error;
}
ops->ent_put(&fatent, FAT_ENT_FREE);
if (sbi->free_clusters != -1) {
sbi->free_clusters++;
sb->s_dirt = 1;
}
if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
if (sb->s_flags & MS_SYNCHRONOUS) {
err = fat_sync_bhs(bhs, nr_bhs);
if (err)
goto error;
}
err = fat_mirror_bhs(sb, bhs, nr_bhs);
if (err)
goto error;
for (i = 0; i < nr_bhs; i++)
brelse(bhs[i]);
nr_bhs = 0;
}
fat_collect_bhs(bhs, &nr_bhs, &fatent);
} while (cluster != FAT_ENT_EOF);
if (sb->s_flags & MS_SYNCHRONOUS) {
err = fat_sync_bhs(bhs, nr_bhs);
if (err)
goto error;
}
err = fat_mirror_bhs(sb, bhs, nr_bhs);
error:
fatent_brelse(&fatent);
for (i = 0; i < nr_bhs; i++)
brelse(bhs[i]);
unlock_fat(sbi);
fat_clusters_flush(sb);
return err;
}
EXPORT_SYMBOL_GPL(fat_free_clusters);
int fat_count_free_clusters(struct super_block *sb)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct fatent_operations *ops = sbi->fatent_ops;
struct fat_entry fatent;
int err = 0, free;
lock_fat(sbi);
if (sbi->free_clusters != -1)
goto out;
free = 0;
fatent_init(&fatent);
fatent_set_entry(&fatent, FAT_START_ENT);
while (fatent.entry < sbi->max_cluster) {
err = fat_ent_read_block(sb, &fatent);
if (err)
goto out;
do {
if (ops->ent_get(&fatent) == FAT_ENT_FREE)
free++;
} while (fat_ent_next(sbi, &fatent));
}
sbi->free_clusters = free;
sb->s_dirt = 1;
fatent_brelse(&fatent);
out:
unlock_fat(sbi);
return err;
}
