linux/fs/fat/cache.c

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/*
* 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/fs.h>
#include <linux/msdos_fs.h>
#include <linux/buffer_head.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 kmem_cache *cachep, unsigned long flags)
{
struct fat_cache *cache = (struct fat_cache *)foo;
if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
SLAB_CTOR_CONSTRUCTOR)
INIT_LIST_HEAD(&cache->cache_list);
}
int __init fat_cache_init(void)
{
fat_cache_cachep = kmem_cache_create("fat_cache",
sizeof(struct fat_cache),
[PATCH] cpuset memory spread: slab cache filesystems Mark file system inode and similar slab caches subject to SLAB_MEM_SPREAD memory spreading. If a slab cache is marked SLAB_MEM_SPREAD, then anytime that a task that's in a cpuset with the 'memory_spread_slab' option enabled goes to allocate from such a slab cache, the allocations are spread evenly over all the memory nodes (task->mems_allowed) allowed to that task, instead of favoring allocation on the node local to the current cpu. The following inode and similar caches are marked SLAB_MEM_SPREAD: file cache ==== ===== fs/adfs/super.c adfs_inode_cache fs/affs/super.c affs_inode_cache fs/befs/linuxvfs.c befs_inode_cache fs/bfs/inode.c bfs_inode_cache fs/block_dev.c bdev_cache fs/cifs/cifsfs.c cifs_inode_cache fs/coda/inode.c coda_inode_cache fs/dquot.c dquot fs/efs/super.c efs_inode_cache fs/ext2/super.c ext2_inode_cache fs/ext2/xattr.c (fs/mbcache.c) ext2_xattr fs/ext3/super.c ext3_inode_cache fs/ext3/xattr.c (fs/mbcache.c) ext3_xattr fs/fat/cache.c fat_cache fs/fat/inode.c fat_inode_cache fs/freevxfs/vxfs_super.c vxfs_inode fs/hpfs/super.c hpfs_inode_cache fs/isofs/inode.c isofs_inode_cache fs/jffs/inode-v23.c jffs_fm fs/jffs2/super.c jffs2_i fs/jfs/super.c jfs_ip fs/minix/inode.c minix_inode_cache fs/ncpfs/inode.c ncp_inode_cache fs/nfs/direct.c nfs_direct_cache fs/nfs/inode.c nfs_inode_cache fs/ntfs/super.c ntfs_big_inode_cache_name fs/ntfs/super.c ntfs_inode_cache fs/ocfs2/dlm/dlmfs.c dlmfs_inode_cache fs/ocfs2/super.c ocfs2_inode_cache fs/proc/inode.c proc_inode_cache fs/qnx4/inode.c qnx4_inode_cache fs/reiserfs/super.c reiser_inode_cache fs/romfs/inode.c romfs_inode_cache fs/smbfs/inode.c smb_inode_cache fs/sysv/inode.c sysv_inode_cache fs/udf/super.c udf_inode_cache fs/ufs/super.c ufs_inode_cache net/socket.c sock_inode_cache net/sunrpc/rpc_pipe.c rpc_inode_cache The choice of which slab caches to so mark was quite simple. I marked those already marked SLAB_RECLAIM_ACCOUNT, except for fs/xfs, dentry_cache, inode_cache, and buffer_head, which were marked in a previous patch. Even though SLAB_RECLAIM_ACCOUNT is for a different purpose, it marks the same potentially large file system i/o related slab caches as we need for memory spreading. Given that the rule now becomes "wherever you would have used a SLAB_RECLAIM_ACCOUNT slab cache flag before (usually the inode cache), use the SLAB_MEM_SPREAD flag too", this should be easy enough to maintain. Future file system writers will just copy one of the existing file system slab cache setups and tend to get it right without thinking. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-24 11:16:05 +00:00
0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
init_once, NULL);
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_KERNEL);
}
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);
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;
const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->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 (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_panic(sb, "%s: detected the cluster chain loop"
" (i_pos %lld)", __FUNCTION__,
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_panic(sb, "%s: invalid cluster chain"
" (i_pos %lld)", __FUNCTION__,
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_panic(sb, "%s: request beyond EOF (i_pos %lld)",
__FUNCTION__, MSDOS_I(inode)->i_pos);
return -EIO;
}
return dclus;
}
int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
unsigned long *mapped_blocks)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
sector_t last_block;
int cluster, offset;
*phys = 0;
*mapped_blocks = 0;
if ((sbi->fat_bits != 32) && (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;
}
last_block = (MSDOS_I(inode)->mmu_private + (sb->s_blocksize - 1))
>> sb->s_blocksize_bits;
if (sector >= last_block)
return 0;
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) {
*phys = 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;
}