387 lines
9.4 KiB
C
387 lines
9.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* linux/fs/fat/cache.c
|
|
*
|
|
* Written 1992,1993 by Werner Almesberger
|
|
*
|
|
* Mar 1999. AV. Changed cache, so that it uses the starting cluster instead
|
|
* of inode number.
|
|
* May 1999. AV. Fixed the bogosity with FAT32 (read "FAT28"). Fscking lusers.
|
|
*/
|
|
|
|
#include <linux/slab.h>
|
|
#include "fat.h"
|
|
|
|
/* this must be > 0. */
|
|
#define FAT_MAX_CACHE 8
|
|
|
|
struct fat_cache {
|
|
struct list_head cache_list;
|
|
int nr_contig; /* number of contiguous clusters */
|
|
int fcluster; /* cluster number in the file. */
|
|
int dcluster; /* cluster number on disk. */
|
|
};
|
|
|
|
struct fat_cache_id {
|
|
unsigned int id;
|
|
int nr_contig;
|
|
int fcluster;
|
|
int dcluster;
|
|
};
|
|
|
|
static inline int fat_max_cache(struct inode *inode)
|
|
{
|
|
return FAT_MAX_CACHE;
|
|
}
|
|
|
|
static struct kmem_cache *fat_cache_cachep;
|
|
|
|
static void init_once(void *foo)
|
|
{
|
|
struct fat_cache *cache = (struct fat_cache *)foo;
|
|
|
|
INIT_LIST_HEAD(&cache->cache_list);
|
|
}
|
|
|
|
int __init fat_cache_init(void)
|
|
{
|
|
fat_cache_cachep = kmem_cache_create("fat_cache",
|
|
sizeof(struct fat_cache),
|
|
0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
|
|
init_once);
|
|
if (fat_cache_cachep == NULL)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
void fat_cache_destroy(void)
|
|
{
|
|
kmem_cache_destroy(fat_cache_cachep);
|
|
}
|
|
|
|
static inline struct fat_cache *fat_cache_alloc(struct inode *inode)
|
|
{
|
|
return kmem_cache_alloc(fat_cache_cachep, GFP_NOFS);
|
|
}
|
|
|
|
static inline void fat_cache_free(struct fat_cache *cache)
|
|
{
|
|
BUG_ON(!list_empty(&cache->cache_list));
|
|
kmem_cache_free(fat_cache_cachep, cache);
|
|
}
|
|
|
|
static inline void fat_cache_update_lru(struct inode *inode,
|
|
struct fat_cache *cache)
|
|
{
|
|
if (MSDOS_I(inode)->cache_lru.next != &cache->cache_list)
|
|
list_move(&cache->cache_list, &MSDOS_I(inode)->cache_lru);
|
|
}
|
|
|
|
static int fat_cache_lookup(struct inode *inode, int fclus,
|
|
struct fat_cache_id *cid,
|
|
int *cached_fclus, int *cached_dclus)
|
|
{
|
|
static struct fat_cache nohit = { .fcluster = 0, };
|
|
|
|
struct fat_cache *hit = &nohit, *p;
|
|
int offset = -1;
|
|
|
|
spin_lock(&MSDOS_I(inode)->cache_lru_lock);
|
|
list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
|
|
/* Find the cache of "fclus" or nearest cache. */
|
|
if (p->fcluster <= fclus && hit->fcluster < p->fcluster) {
|
|
hit = p;
|
|
if ((hit->fcluster + hit->nr_contig) < fclus) {
|
|
offset = hit->nr_contig;
|
|
} else {
|
|
offset = fclus - hit->fcluster;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
if (hit != &nohit) {
|
|
fat_cache_update_lru(inode, hit);
|
|
|
|
cid->id = MSDOS_I(inode)->cache_valid_id;
|
|
cid->nr_contig = hit->nr_contig;
|
|
cid->fcluster = hit->fcluster;
|
|
cid->dcluster = hit->dcluster;
|
|
*cached_fclus = cid->fcluster + offset;
|
|
*cached_dclus = cid->dcluster + offset;
|
|
}
|
|
spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
|
|
|
|
return offset;
|
|
}
|
|
|
|
static struct fat_cache *fat_cache_merge(struct inode *inode,
|
|
struct fat_cache_id *new)
|
|
{
|
|
struct fat_cache *p;
|
|
|
|
list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
|
|
/* Find the same part as "new" in cluster-chain. */
|
|
if (p->fcluster == new->fcluster) {
|
|
BUG_ON(p->dcluster != new->dcluster);
|
|
if (new->nr_contig > p->nr_contig)
|
|
p->nr_contig = new->nr_contig;
|
|
return p;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static void fat_cache_add(struct inode *inode, struct fat_cache_id *new)
|
|
{
|
|
struct fat_cache *cache, *tmp;
|
|
|
|
if (new->fcluster == -1) /* dummy cache */
|
|
return;
|
|
|
|
spin_lock(&MSDOS_I(inode)->cache_lru_lock);
|
|
if (new->id != FAT_CACHE_VALID &&
|
|
new->id != MSDOS_I(inode)->cache_valid_id)
|
|
goto out; /* this cache was invalidated */
|
|
|
|
cache = fat_cache_merge(inode, new);
|
|
if (cache == NULL) {
|
|
if (MSDOS_I(inode)->nr_caches < fat_max_cache(inode)) {
|
|
MSDOS_I(inode)->nr_caches++;
|
|
spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
|
|
|
|
tmp = fat_cache_alloc(inode);
|
|
if (!tmp) {
|
|
spin_lock(&MSDOS_I(inode)->cache_lru_lock);
|
|
MSDOS_I(inode)->nr_caches--;
|
|
spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
|
|
return;
|
|
}
|
|
|
|
spin_lock(&MSDOS_I(inode)->cache_lru_lock);
|
|
cache = fat_cache_merge(inode, new);
|
|
if (cache != NULL) {
|
|
MSDOS_I(inode)->nr_caches--;
|
|
fat_cache_free(tmp);
|
|
goto out_update_lru;
|
|
}
|
|
cache = tmp;
|
|
} else {
|
|
struct list_head *p = MSDOS_I(inode)->cache_lru.prev;
|
|
cache = list_entry(p, struct fat_cache, cache_list);
|
|
}
|
|
cache->fcluster = new->fcluster;
|
|
cache->dcluster = new->dcluster;
|
|
cache->nr_contig = new->nr_contig;
|
|
}
|
|
out_update_lru:
|
|
fat_cache_update_lru(inode, cache);
|
|
out:
|
|
spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
|
|
}
|
|
|
|
/*
|
|
* Cache invalidation occurs rarely, thus the LRU chain is not updated. It
|
|
* fixes itself after a while.
|
|
*/
|
|
static void __fat_cache_inval_inode(struct inode *inode)
|
|
{
|
|
struct msdos_inode_info *i = MSDOS_I(inode);
|
|
struct fat_cache *cache;
|
|
|
|
while (!list_empty(&i->cache_lru)) {
|
|
cache = list_entry(i->cache_lru.next,
|
|
struct fat_cache, cache_list);
|
|
list_del_init(&cache->cache_list);
|
|
i->nr_caches--;
|
|
fat_cache_free(cache);
|
|
}
|
|
/* Update. The copy of caches before this id is discarded. */
|
|
i->cache_valid_id++;
|
|
if (i->cache_valid_id == FAT_CACHE_VALID)
|
|
i->cache_valid_id++;
|
|
}
|
|
|
|
void fat_cache_inval_inode(struct inode *inode)
|
|
{
|
|
spin_lock(&MSDOS_I(inode)->cache_lru_lock);
|
|
__fat_cache_inval_inode(inode);
|
|
spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
|
|
}
|
|
|
|
static inline int cache_contiguous(struct fat_cache_id *cid, int dclus)
|
|
{
|
|
cid->nr_contig++;
|
|
return ((cid->dcluster + cid->nr_contig) == dclus);
|
|
}
|
|
|
|
static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus)
|
|
{
|
|
cid->id = FAT_CACHE_VALID;
|
|
cid->fcluster = fclus;
|
|
cid->dcluster = dclus;
|
|
cid->nr_contig = 0;
|
|
}
|
|
|
|
int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
struct msdos_sb_info *sbi = MSDOS_SB(sb);
|
|
const int limit = sb->s_maxbytes >> sbi->cluster_bits;
|
|
struct fat_entry fatent;
|
|
struct fat_cache_id cid;
|
|
int nr;
|
|
|
|
BUG_ON(MSDOS_I(inode)->i_start == 0);
|
|
|
|
*fclus = 0;
|
|
*dclus = MSDOS_I(inode)->i_start;
|
|
if (!fat_valid_entry(sbi, *dclus)) {
|
|
fat_fs_error_ratelimit(sb,
|
|
"%s: invalid start cluster (i_pos %lld, start %08x)",
|
|
__func__, MSDOS_I(inode)->i_pos, *dclus);
|
|
return -EIO;
|
|
}
|
|
if (cluster == 0)
|
|
return 0;
|
|
|
|
if (fat_cache_lookup(inode, cluster, &cid, fclus, dclus) < 0) {
|
|
/*
|
|
* dummy, always not contiguous
|
|
* This is reinitialized by cache_init(), later.
|
|
*/
|
|
cache_init(&cid, -1, -1);
|
|
}
|
|
|
|
fatent_init(&fatent);
|
|
while (*fclus < cluster) {
|
|
/* prevent the infinite loop of cluster chain */
|
|
if (*fclus > limit) {
|
|
fat_fs_error_ratelimit(sb,
|
|
"%s: detected the cluster chain loop (i_pos %lld)",
|
|
__func__, MSDOS_I(inode)->i_pos);
|
|
nr = -EIO;
|
|
goto out;
|
|
}
|
|
|
|
nr = fat_ent_read(inode, &fatent, *dclus);
|
|
if (nr < 0)
|
|
goto out;
|
|
else if (nr == FAT_ENT_FREE) {
|
|
fat_fs_error_ratelimit(sb,
|
|
"%s: invalid cluster chain (i_pos %lld)",
|
|
__func__, MSDOS_I(inode)->i_pos);
|
|
nr = -EIO;
|
|
goto out;
|
|
} else if (nr == FAT_ENT_EOF) {
|
|
fat_cache_add(inode, &cid);
|
|
goto out;
|
|
}
|
|
(*fclus)++;
|
|
*dclus = nr;
|
|
if (!cache_contiguous(&cid, *dclus))
|
|
cache_init(&cid, *fclus, *dclus);
|
|
}
|
|
nr = 0;
|
|
fat_cache_add(inode, &cid);
|
|
out:
|
|
fatent_brelse(&fatent);
|
|
return nr;
|
|
}
|
|
|
|
static int fat_bmap_cluster(struct inode *inode, int cluster)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
int ret, fclus, dclus;
|
|
|
|
if (MSDOS_I(inode)->i_start == 0)
|
|
return 0;
|
|
|
|
ret = fat_get_cluster(inode, cluster, &fclus, &dclus);
|
|
if (ret < 0)
|
|
return ret;
|
|
else if (ret == FAT_ENT_EOF) {
|
|
fat_fs_error(sb, "%s: request beyond EOF (i_pos %lld)",
|
|
__func__, MSDOS_I(inode)->i_pos);
|
|
return -EIO;
|
|
}
|
|
return dclus;
|
|
}
|
|
|
|
int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
|
|
sector_t last_block,
|
|
unsigned long *mapped_blocks, sector_t *bmap)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
struct msdos_sb_info *sbi = MSDOS_SB(sb);
|
|
int cluster, offset;
|
|
|
|
cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
|
|
offset = sector & (sbi->sec_per_clus - 1);
|
|
cluster = fat_bmap_cluster(inode, cluster);
|
|
if (cluster < 0)
|
|
return cluster;
|
|
else if (cluster) {
|
|
*bmap = fat_clus_to_blknr(sbi, cluster) + offset;
|
|
*mapped_blocks = sbi->sec_per_clus - offset;
|
|
if (*mapped_blocks > last_block - sector)
|
|
*mapped_blocks = last_block - sector;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int is_exceed_eof(struct inode *inode, sector_t sector,
|
|
sector_t *last_block, int create)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
const unsigned long blocksize = sb->s_blocksize;
|
|
const unsigned char blocksize_bits = sb->s_blocksize_bits;
|
|
|
|
*last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
|
|
if (sector >= *last_block) {
|
|
if (!create)
|
|
return 1;
|
|
|
|
/*
|
|
* ->mmu_private can access on only allocation path.
|
|
* (caller must hold ->i_mutex)
|
|
*/
|
|
*last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
|
|
>> blocksize_bits;
|
|
if (sector >= *last_block)
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
|
|
unsigned long *mapped_blocks, int create, bool from_bmap)
|
|
{
|
|
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
|
|
sector_t last_block;
|
|
|
|
*phys = 0;
|
|
*mapped_blocks = 0;
|
|
if (!is_fat32(sbi) && (inode->i_ino == MSDOS_ROOT_INO)) {
|
|
if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
|
|
*phys = sector + sbi->dir_start;
|
|
*mapped_blocks = 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
if (!from_bmap) {
|
|
if (is_exceed_eof(inode, sector, &last_block, create))
|
|
return 0;
|
|
} else {
|
|
last_block = inode->i_blocks >>
|
|
(inode->i_sb->s_blocksize_bits - 9);
|
|
if (sector >= last_block)
|
|
return 0;
|
|
}
|
|
|
|
return fat_get_mapped_cluster(inode, sector, last_block, mapped_blocks,
|
|
phys);
|
|
}
|