![Christoph Lameter](/assets/img/avatar_default.png)
I have never seen a use of SLAB_DEBUG_INITIAL. It is only supported by SLAB. I think its purpose was to have a callback after an object has been freed to verify that the state is the constructor state again? The callback is performed before each freeing of an object. I would think that it is much easier to check the object state manually before the free. That also places the check near the code object manipulation of the object. Also the SLAB_DEBUG_INITIAL callback is only performed if the kernel was compiled with SLAB debugging on. If there would be code in a constructor handling SLAB_DEBUG_INITIAL then it would have to be conditional on SLAB_DEBUG otherwise it would just be dead code. But there is no such code in the kernel. I think SLUB_DEBUG_INITIAL is too problematic to make real use of, difficult to understand and there are easier ways to accomplish the same effect (i.e. add debug code before kfree). There is a related flag SLAB_CTOR_VERIFY that is frequently checked to be clear in fs inode caches. Remove the pointless checks (they would even be pointless without removeal of SLAB_DEBUG_INITIAL) from the fs constructors. This is the last slab flag that SLUB did not support. Remove the check for unimplemented flags from SLUB. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
331 lines
8.1 KiB
C
331 lines
8.1 KiB
C
/*
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* linux/fs/fat/cache.c
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*
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* Written 1992,1993 by Werner Almesberger
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*
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* Mar 1999. AV. Changed cache, so that it uses the starting cluster instead
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* of inode number.
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* May 1999. AV. Fixed the bogosity with FAT32 (read "FAT28"). Fscking lusers.
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*/
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#include <linux/fs.h>
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#include <linux/msdos_fs.h>
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#include <linux/buffer_head.h>
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/* this must be > 0. */
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#define FAT_MAX_CACHE 8
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struct fat_cache {
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struct list_head cache_list;
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int nr_contig; /* number of contiguous clusters */
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int fcluster; /* cluster number in the file. */
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int dcluster; /* cluster number on disk. */
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};
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struct fat_cache_id {
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unsigned int id;
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int nr_contig;
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int fcluster;
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int dcluster;
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};
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static inline int fat_max_cache(struct inode *inode)
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{
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return FAT_MAX_CACHE;
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}
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static struct kmem_cache *fat_cache_cachep;
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static void init_once(void *foo, struct kmem_cache *cachep, unsigned long flags)
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{
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struct fat_cache *cache = (struct fat_cache *)foo;
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if (flags & SLAB_CTOR_CONSTRUCTOR)
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INIT_LIST_HEAD(&cache->cache_list);
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}
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int __init fat_cache_init(void)
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{
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fat_cache_cachep = kmem_cache_create("fat_cache",
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sizeof(struct fat_cache),
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0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
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init_once, NULL);
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if (fat_cache_cachep == NULL)
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return -ENOMEM;
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return 0;
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}
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void fat_cache_destroy(void)
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{
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kmem_cache_destroy(fat_cache_cachep);
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}
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static inline struct fat_cache *fat_cache_alloc(struct inode *inode)
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{
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return kmem_cache_alloc(fat_cache_cachep, GFP_KERNEL);
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}
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static inline void fat_cache_free(struct fat_cache *cache)
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{
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BUG_ON(!list_empty(&cache->cache_list));
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kmem_cache_free(fat_cache_cachep, cache);
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}
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static inline void fat_cache_update_lru(struct inode *inode,
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struct fat_cache *cache)
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{
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if (MSDOS_I(inode)->cache_lru.next != &cache->cache_list)
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list_move(&cache->cache_list, &MSDOS_I(inode)->cache_lru);
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}
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static int fat_cache_lookup(struct inode *inode, int fclus,
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struct fat_cache_id *cid,
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int *cached_fclus, int *cached_dclus)
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{
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static struct fat_cache nohit = { .fcluster = 0, };
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struct fat_cache *hit = &nohit, *p;
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int offset = -1;
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spin_lock(&MSDOS_I(inode)->cache_lru_lock);
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list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
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/* Find the cache of "fclus" or nearest cache. */
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if (p->fcluster <= fclus && hit->fcluster < p->fcluster) {
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hit = p;
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if ((hit->fcluster + hit->nr_contig) < fclus) {
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offset = hit->nr_contig;
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} else {
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offset = fclus - hit->fcluster;
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break;
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}
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}
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}
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if (hit != &nohit) {
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fat_cache_update_lru(inode, hit);
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cid->id = MSDOS_I(inode)->cache_valid_id;
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cid->nr_contig = hit->nr_contig;
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cid->fcluster = hit->fcluster;
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cid->dcluster = hit->dcluster;
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*cached_fclus = cid->fcluster + offset;
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*cached_dclus = cid->dcluster + offset;
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}
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spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
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return offset;
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}
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static struct fat_cache *fat_cache_merge(struct inode *inode,
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struct fat_cache_id *new)
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{
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struct fat_cache *p;
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list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
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/* Find the same part as "new" in cluster-chain. */
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if (p->fcluster == new->fcluster) {
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BUG_ON(p->dcluster != new->dcluster);
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if (new->nr_contig > p->nr_contig)
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p->nr_contig = new->nr_contig;
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return p;
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}
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}
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return NULL;
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}
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static void fat_cache_add(struct inode *inode, struct fat_cache_id *new)
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{
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struct fat_cache *cache, *tmp;
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if (new->fcluster == -1) /* dummy cache */
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return;
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spin_lock(&MSDOS_I(inode)->cache_lru_lock);
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if (new->id != FAT_CACHE_VALID &&
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new->id != MSDOS_I(inode)->cache_valid_id)
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goto out; /* this cache was invalidated */
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cache = fat_cache_merge(inode, new);
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if (cache == NULL) {
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if (MSDOS_I(inode)->nr_caches < fat_max_cache(inode)) {
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MSDOS_I(inode)->nr_caches++;
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spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
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tmp = fat_cache_alloc(inode);
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spin_lock(&MSDOS_I(inode)->cache_lru_lock);
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cache = fat_cache_merge(inode, new);
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if (cache != NULL) {
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MSDOS_I(inode)->nr_caches--;
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fat_cache_free(tmp);
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goto out_update_lru;
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}
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cache = tmp;
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} else {
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struct list_head *p = MSDOS_I(inode)->cache_lru.prev;
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cache = list_entry(p, struct fat_cache, cache_list);
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}
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cache->fcluster = new->fcluster;
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cache->dcluster = new->dcluster;
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cache->nr_contig = new->nr_contig;
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}
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out_update_lru:
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fat_cache_update_lru(inode, cache);
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out:
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spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
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}
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/*
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* Cache invalidation occurs rarely, thus the LRU chain is not updated. It
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* fixes itself after a while.
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*/
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static void __fat_cache_inval_inode(struct inode *inode)
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{
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struct msdos_inode_info *i = MSDOS_I(inode);
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struct fat_cache *cache;
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while (!list_empty(&i->cache_lru)) {
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cache = list_entry(i->cache_lru.next, struct fat_cache, cache_list);
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list_del_init(&cache->cache_list);
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i->nr_caches--;
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fat_cache_free(cache);
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}
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/* Update. The copy of caches before this id is discarded. */
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i->cache_valid_id++;
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if (i->cache_valid_id == FAT_CACHE_VALID)
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i->cache_valid_id++;
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}
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void fat_cache_inval_inode(struct inode *inode)
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{
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spin_lock(&MSDOS_I(inode)->cache_lru_lock);
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__fat_cache_inval_inode(inode);
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spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
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}
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static inline int cache_contiguous(struct fat_cache_id *cid, int dclus)
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{
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cid->nr_contig++;
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return ((cid->dcluster + cid->nr_contig) == dclus);
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}
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static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus)
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{
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cid->id = FAT_CACHE_VALID;
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cid->fcluster = fclus;
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cid->dcluster = dclus;
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cid->nr_contig = 0;
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}
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int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
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{
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struct super_block *sb = inode->i_sb;
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const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->cluster_bits;
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struct fat_entry fatent;
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struct fat_cache_id cid;
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int nr;
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BUG_ON(MSDOS_I(inode)->i_start == 0);
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*fclus = 0;
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*dclus = MSDOS_I(inode)->i_start;
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if (cluster == 0)
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return 0;
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if (fat_cache_lookup(inode, cluster, &cid, fclus, dclus) < 0) {
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/*
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* dummy, always not contiguous
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* This is reinitialized by cache_init(), later.
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*/
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cache_init(&cid, -1, -1);
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}
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fatent_init(&fatent);
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while (*fclus < cluster) {
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/* prevent the infinite loop of cluster chain */
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if (*fclus > limit) {
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fat_fs_panic(sb, "%s: detected the cluster chain loop"
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" (i_pos %lld)", __FUNCTION__,
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MSDOS_I(inode)->i_pos);
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nr = -EIO;
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goto out;
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}
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nr = fat_ent_read(inode, &fatent, *dclus);
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if (nr < 0)
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goto out;
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else if (nr == FAT_ENT_FREE) {
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fat_fs_panic(sb, "%s: invalid cluster chain"
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" (i_pos %lld)", __FUNCTION__,
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MSDOS_I(inode)->i_pos);
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nr = -EIO;
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goto out;
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} else if (nr == FAT_ENT_EOF) {
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fat_cache_add(inode, &cid);
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goto out;
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}
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(*fclus)++;
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*dclus = nr;
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if (!cache_contiguous(&cid, *dclus))
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cache_init(&cid, *fclus, *dclus);
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}
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nr = 0;
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fat_cache_add(inode, &cid);
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out:
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fatent_brelse(&fatent);
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return nr;
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}
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static int fat_bmap_cluster(struct inode *inode, int cluster)
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{
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struct super_block *sb = inode->i_sb;
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int ret, fclus, dclus;
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if (MSDOS_I(inode)->i_start == 0)
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return 0;
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ret = fat_get_cluster(inode, cluster, &fclus, &dclus);
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if (ret < 0)
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return ret;
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else if (ret == FAT_ENT_EOF) {
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fat_fs_panic(sb, "%s: request beyond EOF (i_pos %lld)",
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__FUNCTION__, MSDOS_I(inode)->i_pos);
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return -EIO;
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}
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return dclus;
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}
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int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
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unsigned long *mapped_blocks)
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{
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struct super_block *sb = inode->i_sb;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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sector_t last_block;
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int cluster, offset;
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*phys = 0;
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*mapped_blocks = 0;
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if ((sbi->fat_bits != 32) && (inode->i_ino == MSDOS_ROOT_INO)) {
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if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
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*phys = sector + sbi->dir_start;
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*mapped_blocks = 1;
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}
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return 0;
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}
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last_block = (MSDOS_I(inode)->mmu_private + (sb->s_blocksize - 1))
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>> sb->s_blocksize_bits;
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if (sector >= last_block)
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return 0;
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cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
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offset = sector & (sbi->sec_per_clus - 1);
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cluster = fat_bmap_cluster(inode, cluster);
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if (cluster < 0)
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return cluster;
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else if (cluster) {
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*phys = fat_clus_to_blknr(sbi, cluster) + offset;
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*mapped_blocks = sbi->sec_per_clus - offset;
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if (*mapped_blocks > last_block - sector)
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*mapped_blocks = last_block - sector;
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}
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return 0;
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}
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