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fs/mbcache.c
24.1 KB
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/* * linux/fs/mbcache.c * (C) 2001-2002 Andreas Gruenbacher, <a.gruenbacher@computer.org> */ /* * Filesystem Meta Information Block Cache (mbcache) * * The mbcache caches blocks of block devices that need to be located * by their device/block number, as well as by other criteria (such * as the block's contents). * * There can only be one cache entry in a cache per device and block number. * Additional indexes need not be unique in this sense. The number of * additional indexes (=other criteria) can be hardwired at compile time * or specified at cache create time. * * Each cache entry is of fixed size. An entry may be `valid' or `invalid' * in the cache. A valid entry is in the main hash tables of the cache, * and may also be in the lru list. An invalid entry is not in any hashes * or lists. * * A valid cache entry is only in the lru list if no handles refer to it. * Invalid cache entries will be freed when the last handle to the cache * entry is released. Entries that cannot be freed immediately are put * back on the lru list. */ |
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/* * Lock descriptions and usage: * * Each hash chain of both the block and index hash tables now contains * a built-in lock used to serialize accesses to the hash chain. * * Accesses to global data structures mb_cache_list and mb_cache_lru_list * are serialized via the global spinlock mb_cache_spinlock. * * Each mb_cache_entry contains a spinlock, e_entry_lock, to serialize * accesses to its local data, such as e_used and e_queued. * * Lock ordering: * * Each block hash chain's lock has the highest lock order, followed by an * index hash chain's lock, mb_cache_bg_lock (used to implement mb_cache_entry's * lock), and mb_cach_spinlock, with the lowest order. While holding * either a block or index hash chain lock, a thread can acquire an * mc_cache_bg_lock, which in turn can also acquire mb_cache_spinlock. * * Synchronization: * * Since both mb_cache_entry_get and mb_cache_entry_find scan the block and * index hash chian, it needs to lock the corresponding hash chain. For each * mb_cache_entry within the chain, it needs to lock the mb_cache_entry to * prevent either any simultaneous release or free on the entry and also * to serialize accesses to either the e_used or e_queued member of the entry. * * To avoid having a dangling reference to an already freed * mb_cache_entry, an mb_cache_entry is only freed when it is not on a * block hash chain and also no longer being referenced, both e_used, * and e_queued are 0's. When an mb_cache_entry is explicitly freed it is * first removed from a block hash chain. */ |
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#include <linux/kernel.h> #include <linux/module.h> #include <linux/hash.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/slab.h> #include <linux/sched.h> |
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#include <linux/list_bl.h> |
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#include <linux/mbcache.h> |
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#include <linux/init.h> |
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#include <linux/blockgroup_lock.h> |
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#include <linux/log2.h> |
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#ifdef MB_CACHE_DEBUG # define mb_debug(f...) do { \ printk(KERN_DEBUG f); \ printk(" "); \ } while (0) #define mb_assert(c) do { if (!(c)) \ printk(KERN_ERR "assertion " #c " failed "); \ } while(0) #else # define mb_debug(f...) do { } while(0) # define mb_assert(c) do { } while(0) #endif #define mb_error(f...) do { \ printk(KERN_ERR f); \ printk(" "); \ } while(0) #define MB_CACHE_WRITER ((unsigned short)~0U >> 1) |
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#define MB_CACHE_ENTRY_LOCK_BITS ilog2(NR_BG_LOCKS) |
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#define MB_CACHE_ENTRY_LOCK_INDEX(ce) \ (hash_long((unsigned long)ce, MB_CACHE_ENTRY_LOCK_BITS)) |
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static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue); |
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static struct blockgroup_lock *mb_cache_bg_lock; |
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static struct kmem_cache *mb_cache_kmem_cache; |
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MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbacher@computer.org>"); MODULE_DESCRIPTION("Meta block cache (for extended attributes)"); MODULE_LICENSE("GPL"); EXPORT_SYMBOL(mb_cache_create); EXPORT_SYMBOL(mb_cache_shrink); EXPORT_SYMBOL(mb_cache_destroy); EXPORT_SYMBOL(mb_cache_entry_alloc); EXPORT_SYMBOL(mb_cache_entry_insert); EXPORT_SYMBOL(mb_cache_entry_release); EXPORT_SYMBOL(mb_cache_entry_free); EXPORT_SYMBOL(mb_cache_entry_get); #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) EXPORT_SYMBOL(mb_cache_entry_find_first); EXPORT_SYMBOL(mb_cache_entry_find_next); #endif |
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/* * Global data: list of all mbcache's, lru list, and a spinlock for * accessing cache data structures on SMP machines. The lru list is * global across all mbcaches. */ static LIST_HEAD(mb_cache_list); static LIST_HEAD(mb_cache_lru_list); static DEFINE_SPINLOCK(mb_cache_spinlock); |
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static inline void __spin_lock_mb_cache_entry(struct mb_cache_entry *ce) { spin_lock(bgl_lock_ptr(mb_cache_bg_lock, MB_CACHE_ENTRY_LOCK_INDEX(ce))); } static inline void __spin_unlock_mb_cache_entry(struct mb_cache_entry *ce) { spin_unlock(bgl_lock_ptr(mb_cache_bg_lock, MB_CACHE_ENTRY_LOCK_INDEX(ce))); } |
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static inline int |
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__mb_cache_entry_is_block_hashed(struct mb_cache_entry *ce) |
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{ |
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return !hlist_bl_unhashed(&ce->e_block_list); |
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} |
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static inline void __mb_cache_entry_unhash_block(struct mb_cache_entry *ce) |
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{ |
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if (__mb_cache_entry_is_block_hashed(ce)) hlist_bl_del_init(&ce->e_block_list); } static inline int __mb_cache_entry_is_index_hashed(struct mb_cache_entry *ce) { return !hlist_bl_unhashed(&ce->e_index.o_list); |
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} |
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static inline void __mb_cache_entry_unhash_index(struct mb_cache_entry *ce) { if (__mb_cache_entry_is_index_hashed(ce)) hlist_bl_del_init(&ce->e_index.o_list); } |
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/* * __mb_cache_entry_unhash_unlock() * * This function is called to unhash both the block and index hash * chain. * It assumes both the block and index hash chain is locked upon entry. * It also unlock both hash chains both exit */ |
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static inline void |
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__mb_cache_entry_unhash_unlock(struct mb_cache_entry *ce) |
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{ __mb_cache_entry_unhash_index(ce); |
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hlist_bl_unlock(ce->e_index_hash_p); |
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__mb_cache_entry_unhash_block(ce); |
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hlist_bl_unlock(ce->e_block_hash_p); |
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} |
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static void |
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__mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask) |
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{ struct mb_cache *cache = ce->e_cache; |
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mb_assert(!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))); |
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kmem_cache_free(cache->c_entry_cache, ce); atomic_dec(&cache->c_entry_count); |
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} |
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static void |
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__mb_cache_entry_release(struct mb_cache_entry *ce) |
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{ |
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/* First lock the entry to serialize access to its local data. */ __spin_lock_mb_cache_entry(ce); |
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/* Wake up all processes queuing for this cache entry. */ if (ce->e_queued) wake_up_all(&mb_cache_queue); if (ce->e_used >= MB_CACHE_WRITER) ce->e_used -= MB_CACHE_WRITER; |
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/* * Make sure that all cache entries on lru_list have * both e_used and e_qued of 0s. */ |
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ce->e_used--; |
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if (!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))) { if (!__mb_cache_entry_is_block_hashed(ce)) { __spin_unlock_mb_cache_entry(ce); |
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goto forget; |
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} /* * Need access to lru list, first drop entry lock, * then reacquire the lock in the proper order. */ spin_lock(&mb_cache_spinlock); if (list_empty(&ce->e_lru_list)) list_add_tail(&ce->e_lru_list, &mb_cache_lru_list); spin_unlock(&mb_cache_spinlock); |
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} |
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__spin_unlock_mb_cache_entry(ce); |
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return; forget: |
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mb_assert(list_empty(&ce->e_lru_list)); |
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__mb_cache_entry_forget(ce, GFP_KERNEL); } |
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/* |
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* mb_cache_shrink_scan() memory pressure callback |
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* * This function is called by the kernel memory management when memory * gets low. * |
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* @shrink: (ignored) |
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* @sc: shrink_control passed from reclaim |
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* |
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* Returns the number of objects freed. |
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*/ |
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static unsigned long mb_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) |
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{ LIST_HEAD(free_list); |
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struct mb_cache_entry *entry, *tmp; |
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int nr_to_scan = sc->nr_to_scan; gfp_t gfp_mask = sc->gfp_mask; |
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unsigned long freed = 0; |
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|
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mb_debug("trying to free %d entries", nr_to_scan); |
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spin_lock(&mb_cache_spinlock); |
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while ((nr_to_scan-- > 0) && !list_empty(&mb_cache_lru_list)) { |
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struct mb_cache_entry *ce = list_entry(mb_cache_lru_list.next, |
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struct mb_cache_entry, e_lru_list); list_del_init(&ce->e_lru_list); if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt)) continue; spin_unlock(&mb_cache_spinlock); /* Prevent any find or get operation on the entry */ hlist_bl_lock(ce->e_block_hash_p); hlist_bl_lock(ce->e_index_hash_p); /* Ignore if it is touched by a find/get */ if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt) || !list_empty(&ce->e_lru_list)) { hlist_bl_unlock(ce->e_index_hash_p); hlist_bl_unlock(ce->e_block_hash_p); spin_lock(&mb_cache_spinlock); continue; } __mb_cache_entry_unhash_unlock(ce); list_add_tail(&ce->e_lru_list, &free_list); spin_lock(&mb_cache_spinlock); |
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} spin_unlock(&mb_cache_spinlock); |
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|
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list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) { __mb_cache_entry_forget(entry, gfp_mask); |
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freed++; |
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} |
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return freed; } static unsigned long mb_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { struct mb_cache *cache; unsigned long count = 0; spin_lock(&mb_cache_spinlock); |
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list_for_each_entry(cache, &mb_cache_list, c_cache_list) { mb_debug("cache %s (%d)", cache->c_name, atomic_read(&cache->c_entry_count)); count += atomic_read(&cache->c_entry_count); } |
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spin_unlock(&mb_cache_spinlock); |
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|
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return vfs_pressure_ratio(count); |
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} |
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static struct shrinker mb_cache_shrinker = { .count_objects = mb_cache_shrink_count, .scan_objects = mb_cache_shrink_scan, .seeks = DEFAULT_SEEKS, }; |
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/* * mb_cache_create() create a new cache * * All entries in one cache are equal size. Cache entries may be from * multiple devices. If this is the first mbcache created, registers * the cache with kernel memory management. Returns NULL if no more * memory was available. * * @name: name of the cache (informal) |
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* @bucket_bits: log2(number of hash buckets) */ struct mb_cache * |
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mb_cache_create(const char *name, int bucket_bits) |
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{ |
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int n, bucket_count = 1 << bucket_bits; |
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struct mb_cache *cache = NULL; |
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if (!mb_cache_bg_lock) { mb_cache_bg_lock = kmalloc(sizeof(struct blockgroup_lock), GFP_KERNEL); if (!mb_cache_bg_lock) return NULL; bgl_lock_init(mb_cache_bg_lock); } |
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cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL); |
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if (!cache) |
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return NULL; |
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cache->c_name = name; |
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atomic_set(&cache->c_entry_count, 0); cache->c_bucket_bits = bucket_bits; |
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cache->c_block_hash = kmalloc(bucket_count * sizeof(struct hlist_bl_head), GFP_KERNEL); |
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if (!cache->c_block_hash) goto fail; for (n=0; n<bucket_count; n++) |
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INIT_HLIST_BL_HEAD(&cache->c_block_hash[n]); cache->c_index_hash = kmalloc(bucket_count * sizeof(struct hlist_bl_head), GFP_KERNEL); |
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if (!cache->c_index_hash) goto fail; for (n=0; n<bucket_count; n++) |
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INIT_HLIST_BL_HEAD(&cache->c_index_hash[n]); |
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if (!mb_cache_kmem_cache) { mb_cache_kmem_cache = kmem_cache_create(name, sizeof(struct mb_cache_entry), 0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL); if (!mb_cache_kmem_cache) goto fail2; } cache->c_entry_cache = mb_cache_kmem_cache; |
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/* * Set an upper limit on the number of cache entries so that the hash * chains won't grow too long. */ cache->c_max_entries = bucket_count << 4; |
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spin_lock(&mb_cache_spinlock); list_add(&cache->c_cache_list, &mb_cache_list); spin_unlock(&mb_cache_spinlock); return cache; |
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fail2: kfree(cache->c_index_hash); |
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fail: |
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kfree(cache->c_block_hash); kfree(cache); |
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return NULL; } /* * mb_cache_shrink() * |
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* Removes all cache entries of a device from the cache. All cache entries |
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* currently in use cannot be freed, and thus remain in the cache. All others * are freed. * |
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* @bdev: which device's cache entries to shrink */ void |
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mb_cache_shrink(struct block_device *bdev) |
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{ LIST_HEAD(free_list); |
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struct list_head *l; struct mb_cache_entry *ce, *tmp; |
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l = &mb_cache_lru_list; |
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spin_lock(&mb_cache_spinlock); |
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while (!list_is_last(l, &mb_cache_lru_list)) { l = l->next; ce = list_entry(l, struct mb_cache_entry, e_lru_list); |
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if (ce->e_bdev == bdev) { |
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list_del_init(&ce->e_lru_list); if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt)) continue; spin_unlock(&mb_cache_spinlock); /* * Prevent any find or get operation on the entry. */ hlist_bl_lock(ce->e_block_hash_p); hlist_bl_lock(ce->e_index_hash_p); /* Ignore if it is touched by a find/get */ if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt) || !list_empty(&ce->e_lru_list)) { hlist_bl_unlock(ce->e_index_hash_p); hlist_bl_unlock(ce->e_block_hash_p); l = &mb_cache_lru_list; spin_lock(&mb_cache_spinlock); continue; } __mb_cache_entry_unhash_unlock(ce); mb_assert(!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))); list_add_tail(&ce->e_lru_list, &free_list); l = &mb_cache_lru_list; spin_lock(&mb_cache_spinlock); |
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} } spin_unlock(&mb_cache_spinlock); |
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list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) { __mb_cache_entry_forget(ce, GFP_KERNEL); |
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} } /* * mb_cache_destroy() * * Shrinks the cache to its minimum possible size (hopefully 0 entries), * and then destroys it. If this was the last mbcache, un-registers the * mbcache from kernel memory management. */ void mb_cache_destroy(struct mb_cache *cache) { LIST_HEAD(free_list); |
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struct mb_cache_entry *ce, *tmp; |
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spin_lock(&mb_cache_spinlock); |
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list_for_each_entry_safe(ce, tmp, &mb_cache_lru_list, e_lru_list) { if (ce->e_cache == cache) |
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list_move_tail(&ce->e_lru_list, &free_list); |
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} list_del(&cache->c_cache_list); spin_unlock(&mb_cache_spinlock); |
1f3e55fe0 fs/mbcache.c: dou... |
448 449 450 451 452 453 454 455 456 457 458 |
list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) { list_del_init(&ce->e_lru_list); /* * Prevent any find or get operation on the entry. */ hlist_bl_lock(ce->e_block_hash_p); hlist_bl_lock(ce->e_index_hash_p); mb_assert(!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))); __mb_cache_entry_unhash_unlock(ce); __mb_cache_entry_forget(ce, GFP_KERNEL); |
1da177e4c Linux-2.6.12-rc2 |
459 460 461 462 463 464 465 |
} if (atomic_read(&cache->c_entry_count) > 0) { mb_error("cache %s: %d orphaned entries", cache->c_name, atomic_read(&cache->c_entry_count)); } |
9c191f701 ext4: each filesy... |
466 467 468 469 |
if (list_empty(&mb_cache_list)) { kmem_cache_destroy(mb_cache_kmem_cache); mb_cache_kmem_cache = NULL; } |
2aec7c523 mbcache: Remove u... |
470 |
kfree(cache->c_index_hash); |
1da177e4c Linux-2.6.12-rc2 |
471 472 473 |
kfree(cache->c_block_hash); kfree(cache); } |
1da177e4c Linux-2.6.12-rc2 |
474 475 476 477 478 479 480 481 482 |
/* * mb_cache_entry_alloc() * * Allocates a new cache entry. The new entry will not be valid initially, * and thus cannot be looked up yet. It should be filled with data, and * then inserted into the cache using mb_cache_entry_insert(). Returns NULL * if no more memory was available. */ struct mb_cache_entry * |
335e92e8a vfs: fix possible... |
483 |
mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags) |
1da177e4c Linux-2.6.12-rc2 |
484 |
{ |
1f3e55fe0 fs/mbcache.c: dou... |
485 |
struct mb_cache_entry *ce; |
3a48ee8a4 mbcache: Limit th... |
486 487 |
if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) { |
1f3e55fe0 fs/mbcache.c: dou... |
488 489 490 |
struct list_head *l; l = &mb_cache_lru_list; |
3a48ee8a4 mbcache: Limit th... |
491 |
spin_lock(&mb_cache_spinlock); |
1f3e55fe0 fs/mbcache.c: dou... |
492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 |
while (!list_is_last(l, &mb_cache_lru_list)) { l = l->next; ce = list_entry(l, struct mb_cache_entry, e_lru_list); if (ce->e_cache == cache) { list_del_init(&ce->e_lru_list); if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt)) continue; spin_unlock(&mb_cache_spinlock); /* * Prevent any find or get operation on the * entry. */ hlist_bl_lock(ce->e_block_hash_p); hlist_bl_lock(ce->e_index_hash_p); /* Ignore if it is touched by a find/get */ if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt) || !list_empty(&ce->e_lru_list)) { hlist_bl_unlock(ce->e_index_hash_p); hlist_bl_unlock(ce->e_block_hash_p); l = &mb_cache_lru_list; spin_lock(&mb_cache_spinlock); continue; } mb_assert(list_empty(&ce->e_lru_list)); mb_assert(!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))); __mb_cache_entry_unhash_unlock(ce); goto found; } |
3a48ee8a4 mbcache: Limit th... |
523 524 525 |
} spin_unlock(&mb_cache_spinlock); } |
1f3e55fe0 fs/mbcache.c: dou... |
526 527 528 529 530 531 532 533 534 535 536 537 |
ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags); if (!ce) return NULL; atomic_inc(&cache->c_entry_count); INIT_LIST_HEAD(&ce->e_lru_list); INIT_HLIST_BL_NODE(&ce->e_block_list); INIT_HLIST_BL_NODE(&ce->e_index.o_list); ce->e_cache = cache; ce->e_queued = 0; atomic_set(&ce->e_refcnt, 0); found: |
3e037e521 fs/mbcache.c: cha... |
538 539 |
ce->e_block_hash_p = &cache->c_block_hash[0]; ce->e_index_hash_p = &cache->c_index_hash[0]; |
3a48ee8a4 mbcache: Limit th... |
540 |
ce->e_used = 1 + MB_CACHE_WRITER; |
1da177e4c Linux-2.6.12-rc2 |
541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 |
return ce; } /* * mb_cache_entry_insert() * * Inserts an entry that was allocated using mb_cache_entry_alloc() into * the cache. After this, the cache entry can be looked up, but is not yet * in the lru list as the caller still holds a handle to it. Returns 0 on * success, or -EBUSY if a cache entry for that device + inode exists * already (this may happen after a failed lookup, but when another process * has inserted the same cache entry in the meantime). * * @bdev: device the cache entry belongs to * @block: block number |
2aec7c523 mbcache: Remove u... |
557 |
* @key: lookup key |
1da177e4c Linux-2.6.12-rc2 |
558 559 560 |
*/ int mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev, |
2aec7c523 mbcache: Remove u... |
561 |
sector_t block, unsigned int key) |
1da177e4c Linux-2.6.12-rc2 |
562 563 564 |
{ struct mb_cache *cache = ce->e_cache; unsigned int bucket; |
3e037e521 fs/mbcache.c: cha... |
565 |
struct hlist_bl_node *l; |
3e037e521 fs/mbcache.c: cha... |
566 567 568 |
struct hlist_bl_head *block_hash_p; struct hlist_bl_head *index_hash_p; struct mb_cache_entry *lce; |
1da177e4c Linux-2.6.12-rc2 |
569 |
|
3e037e521 fs/mbcache.c: cha... |
570 |
mb_assert(ce); |
1da177e4c Linux-2.6.12-rc2 |
571 572 |
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), cache->c_bucket_bits); |
3e037e521 fs/mbcache.c: cha... |
573 |
block_hash_p = &cache->c_block_hash[bucket]; |
1f3e55fe0 fs/mbcache.c: dou... |
574 |
hlist_bl_lock(block_hash_p); |
3e037e521 fs/mbcache.c: cha... |
575 |
hlist_bl_for_each_entry(lce, l, block_hash_p, e_block_list) { |
1f3e55fe0 fs/mbcache.c: dou... |
576 577 578 579 |
if (lce->e_bdev == bdev && lce->e_block == block) { hlist_bl_unlock(block_hash_p); return -EBUSY; } |
1da177e4c Linux-2.6.12-rc2 |
580 |
} |
3e037e521 fs/mbcache.c: cha... |
581 |
mb_assert(!__mb_cache_entry_is_block_hashed(ce)); |
1f3e55fe0 fs/mbcache.c: dou... |
582 583 |
__mb_cache_entry_unhash_block(ce); __mb_cache_entry_unhash_index(ce); |
1da177e4c Linux-2.6.12-rc2 |
584 585 |
ce->e_bdev = bdev; ce->e_block = block; |
3e037e521 fs/mbcache.c: cha... |
586 |
ce->e_block_hash_p = block_hash_p; |
2aec7c523 mbcache: Remove u... |
587 |
ce->e_index.o_key = key; |
1f3e55fe0 fs/mbcache.c: dou... |
588 589 |
hlist_bl_add_head(&ce->e_block_list, block_hash_p); hlist_bl_unlock(block_hash_p); |
2aec7c523 mbcache: Remove u... |
590 |
bucket = hash_long(key, cache->c_bucket_bits); |
3e037e521 fs/mbcache.c: cha... |
591 |
index_hash_p = &cache->c_index_hash[bucket]; |
1f3e55fe0 fs/mbcache.c: dou... |
592 |
hlist_bl_lock(index_hash_p); |
3e037e521 fs/mbcache.c: cha... |
593 594 |
ce->e_index_hash_p = index_hash_p; hlist_bl_add_head(&ce->e_index.o_list, index_hash_p); |
1f3e55fe0 fs/mbcache.c: dou... |
595 596 |
hlist_bl_unlock(index_hash_p); return 0; |
1da177e4c Linux-2.6.12-rc2 |
597 598 599 600 601 602 603 604 605 606 607 608 609 |
} /* * mb_cache_entry_release() * * Release a handle to a cache entry. When the last handle to a cache entry * is released it is either freed (if it is invalid) or otherwise inserted * in to the lru list. */ void mb_cache_entry_release(struct mb_cache_entry *ce) { |
1f3e55fe0 fs/mbcache.c: dou... |
610 |
__mb_cache_entry_release(ce); |
1da177e4c Linux-2.6.12-rc2 |
611 612 613 614 615 616 |
} /* * mb_cache_entry_free() * |
1da177e4c Linux-2.6.12-rc2 |
617 618 619 620 |
*/ void mb_cache_entry_free(struct mb_cache_entry *ce) { |
1f3e55fe0 fs/mbcache.c: dou... |
621 |
mb_assert(ce); |
1da177e4c Linux-2.6.12-rc2 |
622 |
mb_assert(list_empty(&ce->e_lru_list)); |
1f3e55fe0 fs/mbcache.c: dou... |
623 624 625 626 627 628 629 |
hlist_bl_lock(ce->e_index_hash_p); __mb_cache_entry_unhash_index(ce); hlist_bl_unlock(ce->e_index_hash_p); hlist_bl_lock(ce->e_block_hash_p); __mb_cache_entry_unhash_block(ce); hlist_bl_unlock(ce->e_block_hash_p); __mb_cache_entry_release(ce); |
1da177e4c Linux-2.6.12-rc2 |
630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 |
} /* * mb_cache_entry_get() * * Get a cache entry by device / block number. (There can only be one entry * in the cache per device and block.) Returns NULL if no such cache entry * exists. The returned cache entry is locked for exclusive access ("single * writer"). */ struct mb_cache_entry * mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev, sector_t block) { unsigned int bucket; |
3e037e521 fs/mbcache.c: cha... |
646 |
struct hlist_bl_node *l; |
1da177e4c Linux-2.6.12-rc2 |
647 |
struct mb_cache_entry *ce; |
3e037e521 fs/mbcache.c: cha... |
648 |
struct hlist_bl_head *block_hash_p; |
1da177e4c Linux-2.6.12-rc2 |
649 650 651 |
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), cache->c_bucket_bits); |
3e037e521 fs/mbcache.c: cha... |
652 |
block_hash_p = &cache->c_block_hash[bucket]; |
1f3e55fe0 fs/mbcache.c: dou... |
653 654 |
/* First serialize access to the block corresponding hash chain. */ hlist_bl_lock(block_hash_p); |
3e037e521 fs/mbcache.c: cha... |
655 656 |
hlist_bl_for_each_entry(ce, l, block_hash_p, e_block_list) { mb_assert(ce->e_block_hash_p == block_hash_p); |
1da177e4c Linux-2.6.12-rc2 |
657 |
if (ce->e_bdev == bdev && ce->e_block == block) { |
1f3e55fe0 fs/mbcache.c: dou... |
658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 |
/* * Prevent a free from removing the entry. */ atomic_inc(&ce->e_refcnt); hlist_bl_unlock(block_hash_p); __spin_lock_mb_cache_entry(ce); atomic_dec(&ce->e_refcnt); if (ce->e_used > 0) { DEFINE_WAIT(wait); while (ce->e_used > 0) { ce->e_queued++; prepare_to_wait(&mb_cache_queue, &wait, TASK_UNINTERRUPTIBLE); __spin_unlock_mb_cache_entry(ce); schedule(); __spin_lock_mb_cache_entry(ce); ce->e_queued--; } finish_wait(&mb_cache_queue, &wait); } ce->e_used += 1 + MB_CACHE_WRITER; __spin_unlock_mb_cache_entry(ce); |
1da177e4c Linux-2.6.12-rc2 |
680 |
|
1f3e55fe0 fs/mbcache.c: dou... |
681 682 |
if (!list_empty(&ce->e_lru_list)) { spin_lock(&mb_cache_spinlock); |
1da177e4c Linux-2.6.12-rc2 |
683 |
list_del_init(&ce->e_lru_list); |
1da177e4c Linux-2.6.12-rc2 |
684 |
spin_unlock(&mb_cache_spinlock); |
1da177e4c Linux-2.6.12-rc2 |
685 |
} |
3e037e521 fs/mbcache.c: cha... |
686 |
if (!__mb_cache_entry_is_block_hashed(ce)) { |
1f3e55fe0 fs/mbcache.c: dou... |
687 |
__mb_cache_entry_release(ce); |
1da177e4c Linux-2.6.12-rc2 |
688 689 |
return NULL; } |
1f3e55fe0 fs/mbcache.c: dou... |
690 |
return ce; |
1da177e4c Linux-2.6.12-rc2 |
691 692 |
} } |
1f3e55fe0 fs/mbcache.c: dou... |
693 694 |
hlist_bl_unlock(block_hash_p); return NULL; |
1da177e4c Linux-2.6.12-rc2 |
695 696 697 698 699 |
} #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) static struct mb_cache_entry * |
3e037e521 fs/mbcache.c: cha... |
700 |
__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head, |
2aec7c523 mbcache: Remove u... |
701 |
struct block_device *bdev, unsigned int key) |
1da177e4c Linux-2.6.12-rc2 |
702 |
{ |
1f3e55fe0 fs/mbcache.c: dou... |
703 704 |
/* The index hash chain is alredy acquire by caller. */ |
3e037e521 fs/mbcache.c: cha... |
705 |
while (l != NULL) { |
1da177e4c Linux-2.6.12-rc2 |
706 |
struct mb_cache_entry *ce = |
3e037e521 fs/mbcache.c: cha... |
707 708 709 |
hlist_bl_entry(l, struct mb_cache_entry, e_index.o_list); mb_assert(ce->e_index_hash_p == head); |
2aec7c523 mbcache: Remove u... |
710 |
if (ce->e_bdev == bdev && ce->e_index.o_key == key) { |
1f3e55fe0 fs/mbcache.c: dou... |
711 712 713 714 715 716 717 718 |
/* * Prevent a free from removing the entry. */ atomic_inc(&ce->e_refcnt); hlist_bl_unlock(head); __spin_lock_mb_cache_entry(ce); atomic_dec(&ce->e_refcnt); ce->e_used++; |
1da177e4c Linux-2.6.12-rc2 |
719 720 |
/* Incrementing before holding the lock gives readers priority over writers. */ |
1f3e55fe0 fs/mbcache.c: dou... |
721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 |
if (ce->e_used >= MB_CACHE_WRITER) { DEFINE_WAIT(wait); while (ce->e_used >= MB_CACHE_WRITER) { ce->e_queued++; prepare_to_wait(&mb_cache_queue, &wait, TASK_UNINTERRUPTIBLE); __spin_unlock_mb_cache_entry(ce); schedule(); __spin_lock_mb_cache_entry(ce); ce->e_queued--; } finish_wait(&mb_cache_queue, &wait); } __spin_unlock_mb_cache_entry(ce); if (!list_empty(&ce->e_lru_list)) { |
1da177e4c Linux-2.6.12-rc2 |
737 |
spin_lock(&mb_cache_spinlock); |
1f3e55fe0 fs/mbcache.c: dou... |
738 739 |
list_del_init(&ce->e_lru_list); spin_unlock(&mb_cache_spinlock); |
1da177e4c Linux-2.6.12-rc2 |
740 |
} |
3e037e521 fs/mbcache.c: cha... |
741 |
if (!__mb_cache_entry_is_block_hashed(ce)) { |
1f3e55fe0 fs/mbcache.c: dou... |
742 |
__mb_cache_entry_release(ce); |
1da177e4c Linux-2.6.12-rc2 |
743 744 745 746 747 748 |
return ERR_PTR(-EAGAIN); } return ce; } l = l->next; } |
1f3e55fe0 fs/mbcache.c: dou... |
749 |
hlist_bl_unlock(head); |
1da177e4c Linux-2.6.12-rc2 |
750 751 752 753 754 755 756 757 |
return NULL; } /* * mb_cache_entry_find_first() * * Find the first cache entry on a given device with a certain key in |
25985edce Fix common misspe... |
758 |
* an additional index. Additional matches can be found with |
1da177e4c Linux-2.6.12-rc2 |
759 760 761 762 |
* mb_cache_entry_find_next(). Returns NULL if no match was found. The * returned cache entry is locked for shared access ("multiple readers"). * * @cache: the cache to search |
1da177e4c Linux-2.6.12-rc2 |
763 764 765 766 |
* @bdev: the device the cache entry should belong to * @key: the key in the index */ struct mb_cache_entry * |
2aec7c523 mbcache: Remove u... |
767 768 |
mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev, unsigned int key) |
1da177e4c Linux-2.6.12-rc2 |
769 770 |
{ unsigned int bucket = hash_long(key, cache->c_bucket_bits); |
3e037e521 fs/mbcache.c: cha... |
771 772 773 |
struct hlist_bl_node *l; struct mb_cache_entry *ce = NULL; struct hlist_bl_head *index_hash_p; |
1da177e4c Linux-2.6.12-rc2 |
774 |
|
3e037e521 fs/mbcache.c: cha... |
775 |
index_hash_p = &cache->c_index_hash[bucket]; |
1f3e55fe0 fs/mbcache.c: dou... |
776 |
hlist_bl_lock(index_hash_p); |
3e037e521 fs/mbcache.c: cha... |
777 778 779 |
if (!hlist_bl_empty(index_hash_p)) { l = hlist_bl_first(index_hash_p); ce = __mb_cache_entry_find(l, index_hash_p, bdev, key); |
1f3e55fe0 fs/mbcache.c: dou... |
780 781 |
} else hlist_bl_unlock(index_hash_p); |
1da177e4c Linux-2.6.12-rc2 |
782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 |
return ce; } /* * mb_cache_entry_find_next() * * Find the next cache entry on a given device with a certain key in an * additional index. Returns NULL if no match could be found. The previous * entry is atomatically released, so that mb_cache_entry_find_next() can * be called like this: * * entry = mb_cache_entry_find_first(); * while (entry) { * ... * entry = mb_cache_entry_find_next(entry, ...); * } * * @prev: The previous match |
1da177e4c Linux-2.6.12-rc2 |
801 802 803 804 |
* @bdev: the device the cache entry should belong to * @key: the key in the index */ struct mb_cache_entry * |
2aec7c523 mbcache: Remove u... |
805 |
mb_cache_entry_find_next(struct mb_cache_entry *prev, |
1da177e4c Linux-2.6.12-rc2 |
806 807 808 809 |
struct block_device *bdev, unsigned int key) { struct mb_cache *cache = prev->e_cache; unsigned int bucket = hash_long(key, cache->c_bucket_bits); |
3e037e521 fs/mbcache.c: cha... |
810 |
struct hlist_bl_node *l; |
1da177e4c Linux-2.6.12-rc2 |
811 |
struct mb_cache_entry *ce; |
3e037e521 fs/mbcache.c: cha... |
812 |
struct hlist_bl_head *index_hash_p; |
1da177e4c Linux-2.6.12-rc2 |
813 |
|
3e037e521 fs/mbcache.c: cha... |
814 815 |
index_hash_p = &cache->c_index_hash[bucket]; mb_assert(prev->e_index_hash_p == index_hash_p); |
1f3e55fe0 fs/mbcache.c: dou... |
816 |
hlist_bl_lock(index_hash_p); |
3e037e521 fs/mbcache.c: cha... |
817 |
mb_assert(!hlist_bl_empty(index_hash_p)); |
2aec7c523 mbcache: Remove u... |
818 |
l = prev->e_index.o_list.next; |
3e037e521 fs/mbcache.c: cha... |
819 |
ce = __mb_cache_entry_find(l, index_hash_p, bdev, key); |
1f3e55fe0 fs/mbcache.c: dou... |
820 |
__mb_cache_entry_release(prev); |
1da177e4c Linux-2.6.12-rc2 |
821 822 823 824 825 826 827 |
return ce; } #endif /* !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) */ static int __init init_mbcache(void) { |
8e1f936b7 mm: clean up and ... |
828 |
register_shrinker(&mb_cache_shrinker); |
1da177e4c Linux-2.6.12-rc2 |
829 830 831 832 833 |
return 0; } static void __exit exit_mbcache(void) { |
8e1f936b7 mm: clean up and ... |
834 |
unregister_shrinker(&mb_cache_shrinker); |
1da177e4c Linux-2.6.12-rc2 |
835 836 837 838 |
} module_init(init_mbcache) module_exit(exit_mbcache) |