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@@ -1,858 +1,433 @@
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-/*
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- * linux/fs/mbcache.c
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- * (C) 2001-2002 Andreas Gruenbacher, <a.gruenbacher@computer.org>
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- */
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-
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-/*
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- * Filesystem Meta Information Block Cache (mbcache)
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- *
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- * The mbcache caches blocks of block devices that need to be located
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- * by their device/block number, as well as by other criteria (such
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- * as the block's contents).
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- *
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- * There can only be one cache entry in a cache per device and block number.
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- * Additional indexes need not be unique in this sense. The number of
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- * additional indexes (=other criteria) can be hardwired at compile time
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- * or specified at cache create time.
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- *
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- * Each cache entry is of fixed size. An entry may be `valid' or `invalid'
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- * in the cache. A valid entry is in the main hash tables of the cache,
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- * and may also be in the lru list. An invalid entry is not in any hashes
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- * or lists.
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- *
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- * A valid cache entry is only in the lru list if no handles refer to it.
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- * Invalid cache entries will be freed when the last handle to the cache
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- * entry is released. Entries that cannot be freed immediately are put
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- * back on the lru list.
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- */
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-
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-/*
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- * Lock descriptions and usage:
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- *
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- * Each hash chain of both the block and index hash tables now contains
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- * a built-in lock used to serialize accesses to the hash chain.
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- *
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- * Accesses to global data structures mb_cache_list and mb_cache_lru_list
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- * are serialized via the global spinlock mb_cache_spinlock.
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- *
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- * Each mb_cache_entry contains a spinlock, e_entry_lock, to serialize
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- * accesses to its local data, such as e_used and e_queued.
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- *
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- * Lock ordering:
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- *
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- * Each block hash chain's lock has the highest lock order, followed by an
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- * index hash chain's lock, mb_cache_bg_lock (used to implement mb_cache_entry's
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- * lock), and mb_cach_spinlock, with the lowest order. While holding
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- * either a block or index hash chain lock, a thread can acquire an
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- * mc_cache_bg_lock, which in turn can also acquire mb_cache_spinlock.
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- *
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- * Synchronization:
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- *
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- * Since both mb_cache_entry_get and mb_cache_entry_find scan the block and
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- * index hash chian, it needs to lock the corresponding hash chain. For each
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- * mb_cache_entry within the chain, it needs to lock the mb_cache_entry to
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- * prevent either any simultaneous release or free on the entry and also
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- * to serialize accesses to either the e_used or e_queued member of the entry.
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- *
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- * To avoid having a dangling reference to an already freed
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- * mb_cache_entry, an mb_cache_entry is only freed when it is not on a
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- * block hash chain and also no longer being referenced, both e_used,
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- * and e_queued are 0's. When an mb_cache_entry is explicitly freed it is
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- * first removed from a block hash chain.
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- */
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-
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-#include <linux/kernel.h>
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-#include <linux/module.h>
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-
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-#include <linux/hash.h>
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-#include <linux/fs.h>
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-#include <linux/mm.h>
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+#include <linux/spinlock.h>
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#include <linux/slab.h>
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-#include <linux/sched.h>
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+#include <linux/list.h>
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#include <linux/list_bl.h>
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+#include <linux/module.h>
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+#include <linux/sched.h>
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+#include <linux/workqueue.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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-
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-#ifdef MB_CACHE_DEBUG
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-# define mb_debug(f...) do { \
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- printk(KERN_DEBUG f); \
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- printk("\n"); \
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- } while (0)
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-#define mb_assert(c) do { if (!(c)) \
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- printk(KERN_ERR "assertion " #c " failed\n"); \
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- } while(0)
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-#else
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-# define mb_debug(f...) do { } while(0)
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-# define mb_assert(c) do { } while(0)
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-#endif
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-#define mb_error(f...) do { \
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- printk(KERN_ERR f); \
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- printk("\n"); \
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- } while(0)
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-
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-#define MB_CACHE_WRITER ((unsigned short)~0U >> 1)
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-
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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) \
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- (hash_long((unsigned long)ce, MB_CACHE_ENTRY_LOCK_BITS))
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-
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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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-
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-MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbacher@computer.org>");
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-MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
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-MODULE_LICENSE("GPL");
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-
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-EXPORT_SYMBOL(mb_cache_create);
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-EXPORT_SYMBOL(mb_cache_shrink);
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-EXPORT_SYMBOL(mb_cache_destroy);
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-EXPORT_SYMBOL(mb_cache_entry_alloc);
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-EXPORT_SYMBOL(mb_cache_entry_insert);
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-EXPORT_SYMBOL(mb_cache_entry_release);
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-EXPORT_SYMBOL(mb_cache_entry_free);
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-EXPORT_SYMBOL(mb_cache_entry_get);
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-#if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
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-EXPORT_SYMBOL(mb_cache_entry_find_first);
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-EXPORT_SYMBOL(mb_cache_entry_find_next);
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-#endif
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/*
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- * Global data: list of all mbcache's, lru list, and a spinlock for
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- * accessing cache data structures on SMP machines. The lru list is
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- * global across all mbcaches.
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+ * Mbcache is a simple key-value store. Keys need not be unique, however
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+ * key-value pairs are expected to be unique (we use this fact in
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+ * mb_cache_entry_delete_block()).
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+ *
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+ * Ext2 and ext4 use this cache for deduplication of extended attribute blocks.
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+ * They use hash of a block contents as a key and block number as a value.
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+ * That's why keys need not be unique (different xattr blocks may end up having
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+ * the same hash). However block number always uniquely identifies a cache
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+ * entry.
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+ *
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+ * We provide functions for creation and removal of entries, search by key,
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+ * and a special "delete entry with given key-value pair" operation. Fixed
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+ * size hash table is used for fast key lookups.
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*/
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-static LIST_HEAD(mb_cache_list);
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-static LIST_HEAD(mb_cache_lru_list);
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-static DEFINE_SPINLOCK(mb_cache_spinlock);
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-
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-static inline void
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-__spin_lock_mb_cache_entry(struct mb_cache_entry *ce)
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-{
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- spin_lock(bgl_lock_ptr(mb_cache_bg_lock,
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- MB_CACHE_ENTRY_LOCK_INDEX(ce)));
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-}
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-
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-static inline void
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-__spin_unlock_mb_cache_entry(struct mb_cache_entry *ce)
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-{
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- spin_unlock(bgl_lock_ptr(mb_cache_bg_lock,
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- MB_CACHE_ENTRY_LOCK_INDEX(ce)));
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-}
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-
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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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+struct mb_cache {
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+ /* Hash table of entries */
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+ struct hlist_bl_head *c_hash;
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+ /* log2 of hash table size */
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+ int c_bucket_bits;
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+ /* Maximum entries in cache to avoid degrading hash too much */
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+ int c_max_entries;
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+ /* Protects c_list, c_entry_count */
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+ spinlock_t c_list_lock;
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+ struct list_head c_list;
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+ /* Number of entries in cache */
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+ unsigned long c_entry_count;
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+ struct shrinker c_shrink;
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+ /* Work for shrinking when the cache has too many entries */
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+ struct work_struct c_shrink_work;
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+};
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+static struct kmem_cache *mb_entry_cache;
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-static inline void
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-__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))
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- hlist_bl_del_init(&ce->e_block_list);
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-}
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+static unsigned long mb_cache_shrink(struct mb_cache *cache,
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+ unsigned int nr_to_scan);
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-static inline int
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-__mb_cache_entry_is_index_hashed(struct mb_cache_entry *ce)
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+static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache,
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+ u32 key)
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{
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- return !hlist_bl_unhashed(&ce->e_index.o_list);
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+ return &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
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}
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-static inline void
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-__mb_cache_entry_unhash_index(struct mb_cache_entry *ce)
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-{
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- if (__mb_cache_entry_is_index_hashed(ce))
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- hlist_bl_del_init(&ce->e_index.o_list);
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-}
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+/*
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+ * Number of entries to reclaim synchronously when there are too many entries
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+ * in cache
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+ */
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+#define SYNC_SHRINK_BATCH 64
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/*
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- * __mb_cache_entry_unhash_unlock()
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- *
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- * This function is called to unhash both the block and index hash
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- * chain.
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- * It assumes both the block and index hash chain is locked upon entry.
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- * It also unlock both hash chains both exit
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+ * mb_cache_entry_create - create entry in cache
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+ * @cache - cache where the entry should be created
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+ * @mask - gfp mask with which the entry should be allocated
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+ * @key - key of the entry
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+ * @block - block that contains data
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+ * @reusable - is the block reusable by other inodes?
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+ *
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+ * Creates entry in @cache with key @key and records that data is stored in
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+ * block @block. The function returns -EBUSY if entry with the same key
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+ * and for the same block already exists in cache. Otherwise 0 is returned.
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*/
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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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+int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
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+ sector_t block, bool reusable)
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{
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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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+ struct mb_cache_entry *entry, *dup;
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+ struct hlist_bl_node *dup_node;
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+ struct hlist_bl_head *head;
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+
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+ /* Schedule background reclaim if there are too many entries */
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+ if (cache->c_entry_count >= cache->c_max_entries)
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+ schedule_work(&cache->c_shrink_work);
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+ /* Do some sync reclaim if background reclaim cannot keep up */
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+ if (cache->c_entry_count >= 2*cache->c_max_entries)
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+ mb_cache_shrink(cache, SYNC_SHRINK_BATCH);
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+
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+ entry = kmem_cache_alloc(mb_entry_cache, mask);
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+ if (!entry)
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+ return -ENOMEM;
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+
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+ INIT_LIST_HEAD(&entry->e_list);
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+ /* One ref for hash, one ref returned */
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+ atomic_set(&entry->e_refcnt, 1);
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+ entry->e_key = key;
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+ entry->e_block = block;
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+ entry->e_reusable = reusable;
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+ head = mb_cache_entry_head(cache, key);
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+ hlist_bl_lock(head);
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+ hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {
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+ if (dup->e_key == key && dup->e_block == block) {
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+ hlist_bl_unlock(head);
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+ kmem_cache_free(mb_entry_cache, entry);
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+ return -EBUSY;
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+ }
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+ }
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+ hlist_bl_add_head(&entry->e_hash_list, head);
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+ hlist_bl_unlock(head);
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+
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+ spin_lock(&cache->c_list_lock);
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+ list_add_tail(&entry->e_list, &cache->c_list);
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+ /* Grab ref for LRU list */
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+ atomic_inc(&entry->e_refcnt);
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+ cache->c_entry_count++;
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+ spin_unlock(&cache->c_list_lock);
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+
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+ return 0;
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}
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+EXPORT_SYMBOL(mb_cache_entry_create);
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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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+void __mb_cache_entry_free(struct mb_cache_entry *entry)
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{
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- struct mb_cache *cache = ce->e_cache;
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-
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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);
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- atomic_dec(&cache->c_entry_count);
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+ kmem_cache_free(mb_entry_cache, entry);
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}
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+EXPORT_SYMBOL(__mb_cache_entry_free);
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-static void
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-__mb_cache_entry_release(struct mb_cache_entry *ce)
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+static struct mb_cache_entry *__entry_find(struct mb_cache *cache,
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+ struct mb_cache_entry *entry,
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+ u32 key)
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{
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- /* First lock the entry to serialize access to its local data. */
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- __spin_lock_mb_cache_entry(ce);
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- /* Wake up all processes queuing for this cache entry. */
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- if (ce->e_queued)
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- wake_up_all(&mb_cache_queue);
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- if (ce->e_used >= MB_CACHE_WRITER)
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- ce->e_used -= MB_CACHE_WRITER;
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- /*
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- * Make sure that all cache entries on lru_list have
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- * both e_used and e_qued of 0s.
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- */
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- ce->e_used--;
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- if (!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))) {
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- if (!__mb_cache_entry_is_block_hashed(ce)) {
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- __spin_unlock_mb_cache_entry(ce);
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- goto forget;
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+ struct mb_cache_entry *old_entry = entry;
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+ struct hlist_bl_node *node;
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+ struct hlist_bl_head *head;
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+
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+ head = mb_cache_entry_head(cache, key);
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+ hlist_bl_lock(head);
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+ if (entry && !hlist_bl_unhashed(&entry->e_hash_list))
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+ node = entry->e_hash_list.next;
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+ else
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+ node = hlist_bl_first(head);
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+ while (node) {
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+ entry = hlist_bl_entry(node, struct mb_cache_entry,
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+ e_hash_list);
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+ if (entry->e_key == key && entry->e_reusable) {
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+ atomic_inc(&entry->e_refcnt);
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+ goto out;
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}
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- /*
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- * Need access to lru list, first drop entry lock,
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- * then reacquire the lock in the proper order.
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- */
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- spin_lock(&mb_cache_spinlock);
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- if (list_empty(&ce->e_lru_list))
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- list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
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- spin_unlock(&mb_cache_spinlock);
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+ node = node->next;
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}
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- __spin_unlock_mb_cache_entry(ce);
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- return;
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-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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+ entry = NULL;
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+out:
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+ hlist_bl_unlock(head);
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+ if (old_entry)
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+ mb_cache_entry_put(cache, old_entry);
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+
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+ return entry;
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}
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/*
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- * mb_cache_shrink_scan() memory pressure callback
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- *
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- * This function is called by the kernel memory management when memory
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- * gets low.
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+ * mb_cache_entry_find_first - find the first entry in cache with given key
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+ * @cache: cache where we should search
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+ * @key: key to look for
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*
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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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|
|
+ * Search in @cache for entry with key @key. Grabs reference to the first
|
|
|
+ * entry found and returns the entry.
|
|
|
*/
|
|
|
-static unsigned long
|
|
|
-mb_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
|
|
|
+struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
|
|
|
+ u32 key)
|
|
|
{
|
|
|
- LIST_HEAD(free_list);
|
|
|
- struct mb_cache_entry *entry, *tmp;
|
|
|
- int nr_to_scan = sc->nr_to_scan;
|
|
|
- gfp_t gfp_mask = sc->gfp_mask;
|
|
|
- unsigned long freed = 0;
|
|
|
-
|
|
|
- mb_debug("trying to free %d entries", nr_to_scan);
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- while ((nr_to_scan-- > 0) && !list_empty(&mb_cache_lru_list)) {
|
|
|
- struct mb_cache_entry *ce =
|
|
|
- list_entry(mb_cache_lru_list.next,
|
|
|
- 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);
|
|
|
- }
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
-
|
|
|
- list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
|
|
|
- __mb_cache_entry_forget(entry, gfp_mask);
|
|
|
- freed++;
|
|
|
- }
|
|
|
- return freed;
|
|
|
+ return __entry_find(cache, NULL, key);
|
|
|
}
|
|
|
+EXPORT_SYMBOL(mb_cache_entry_find_first);
|
|
|
|
|
|
-static unsigned long
|
|
|
-mb_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
|
|
|
+/*
|
|
|
+ * mb_cache_entry_find_next - find next entry in cache with the same
|
|
|
+ * @cache: cache where we should search
|
|
|
+ * @entry: entry to start search from
|
|
|
+ *
|
|
|
+ * Finds next entry in the hash chain which has the same key as @entry.
|
|
|
+ * If @entry is unhashed (which can happen when deletion of entry races
|
|
|
+ * with the search), finds the first entry in the hash chain. The function
|
|
|
+ * drops reference to @entry and returns with a reference to the found entry.
|
|
|
+ */
|
|
|
+struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
|
|
|
+ struct mb_cache_entry *entry)
|
|
|
{
|
|
|
- struct mb_cache *cache;
|
|
|
- unsigned long count = 0;
|
|
|
-
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- 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);
|
|
|
- }
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
-
|
|
|
- return vfs_pressure_ratio(count);
|
|
|
+ return __entry_find(cache, entry, entry->e_key);
|
|
|
}
|
|
|
-
|
|
|
-static struct shrinker mb_cache_shrinker = {
|
|
|
- .count_objects = mb_cache_shrink_count,
|
|
|
- .scan_objects = mb_cache_shrink_scan,
|
|
|
- .seeks = DEFAULT_SEEKS,
|
|
|
-};
|
|
|
+EXPORT_SYMBOL(mb_cache_entry_find_next);
|
|
|
|
|
|
/*
|
|
|
- * 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)
|
|
|
- * @bucket_bits: log2(number of hash buckets)
|
|
|
+ * mb_cache_entry_get - get a cache entry by block number (and key)
|
|
|
+ * @cache - cache we work with
|
|
|
+ * @key - key of block number @block
|
|
|
+ * @block - block number
|
|
|
*/
|
|
|
-struct mb_cache *
|
|
|
-mb_cache_create(const char *name, int bucket_bits)
|
|
|
+struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
|
|
|
+ sector_t block)
|
|
|
{
|
|
|
- int n, bucket_count = 1 << bucket_bits;
|
|
|
- struct mb_cache *cache = NULL;
|
|
|
-
|
|
|
- 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);
|
|
|
- }
|
|
|
-
|
|
|
- cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL);
|
|
|
- if (!cache)
|
|
|
- return NULL;
|
|
|
- cache->c_name = name;
|
|
|
- atomic_set(&cache->c_entry_count, 0);
|
|
|
- cache->c_bucket_bits = bucket_bits;
|
|
|
- cache->c_block_hash = kmalloc(bucket_count *
|
|
|
- sizeof(struct hlist_bl_head), GFP_KERNEL);
|
|
|
- if (!cache->c_block_hash)
|
|
|
- goto fail;
|
|
|
- for (n=0; n<bucket_count; n++)
|
|
|
- INIT_HLIST_BL_HEAD(&cache->c_block_hash[n]);
|
|
|
- cache->c_index_hash = kmalloc(bucket_count *
|
|
|
- sizeof(struct hlist_bl_head), GFP_KERNEL);
|
|
|
- if (!cache->c_index_hash)
|
|
|
- goto fail;
|
|
|
- for (n=0; n<bucket_count; n++)
|
|
|
- INIT_HLIST_BL_HEAD(&cache->c_index_hash[n]);
|
|
|
- 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;
|
|
|
+ struct hlist_bl_node *node;
|
|
|
+ struct hlist_bl_head *head;
|
|
|
+ struct mb_cache_entry *entry;
|
|
|
+
|
|
|
+ head = mb_cache_entry_head(cache, key);
|
|
|
+ hlist_bl_lock(head);
|
|
|
+ hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
|
|
|
+ if (entry->e_key == key && entry->e_block == block) {
|
|
|
+ atomic_inc(&entry->e_refcnt);
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
}
|
|
|
- cache->c_entry_cache = mb_cache_kmem_cache;
|
|
|
-
|
|
|
- /*
|
|
|
- * 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;
|
|
|
-
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- list_add(&cache->c_cache_list, &mb_cache_list);
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
- return cache;
|
|
|
-
|
|
|
-fail2:
|
|
|
- kfree(cache->c_index_hash);
|
|
|
-
|
|
|
-fail:
|
|
|
- kfree(cache->c_block_hash);
|
|
|
- kfree(cache);
|
|
|
- return NULL;
|
|
|
+ entry = NULL;
|
|
|
+out:
|
|
|
+ hlist_bl_unlock(head);
|
|
|
+ return entry;
|
|
|
}
|
|
|
+EXPORT_SYMBOL(mb_cache_entry_get);
|
|
|
|
|
|
-
|
|
|
-/*
|
|
|
- * mb_cache_shrink()
|
|
|
- *
|
|
|
- * Removes all cache entries of a device from the cache. All cache entries
|
|
|
- * currently in use cannot be freed, and thus remain in the cache. All others
|
|
|
- * are freed.
|
|
|
+/* mb_cache_entry_delete_block - remove information about block from cache
|
|
|
+ * @cache - cache we work with
|
|
|
+ * @key - key of block @block
|
|
|
+ * @block - block number
|
|
|
*
|
|
|
- * @bdev: which device's cache entries to shrink
|
|
|
+ * Remove entry from cache @cache with key @key with data stored in @block.
|
|
|
*/
|
|
|
-void
|
|
|
-mb_cache_shrink(struct block_device *bdev)
|
|
|
+void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
|
|
|
+ sector_t block)
|
|
|
{
|
|
|
- LIST_HEAD(free_list);
|
|
|
- struct list_head *l;
|
|
|
- struct mb_cache_entry *ce, *tmp;
|
|
|
-
|
|
|
- l = &mb_cache_lru_list;
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- 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_bdev == bdev) {
|
|
|
- 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;
|
|
|
+ struct hlist_bl_node *node;
|
|
|
+ struct hlist_bl_head *head;
|
|
|
+ struct mb_cache_entry *entry;
|
|
|
+
|
|
|
+ head = mb_cache_entry_head(cache, key);
|
|
|
+ hlist_bl_lock(head);
|
|
|
+ hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
|
|
|
+ if (entry->e_key == key && entry->e_block == block) {
|
|
|
+ /* We keep hash list reference to keep entry alive */
|
|
|
+ hlist_bl_del_init(&entry->e_hash_list);
|
|
|
+ hlist_bl_unlock(head);
|
|
|
+ spin_lock(&cache->c_list_lock);
|
|
|
+ if (!list_empty(&entry->e_list)) {
|
|
|
+ list_del_init(&entry->e_list);
|
|
|
+ cache->c_entry_count--;
|
|
|
+ atomic_dec(&entry->e_refcnt);
|
|
|
}
|
|
|
- __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);
|
|
|
+ spin_unlock(&cache->c_list_lock);
|
|
|
+ mb_cache_entry_put(cache, entry);
|
|
|
+ return;
|
|
|
}
|
|
|
}
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
-
|
|
|
- list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) {
|
|
|
- __mb_cache_entry_forget(ce, GFP_KERNEL);
|
|
|
- }
|
|
|
+ hlist_bl_unlock(head);
|
|
|
}
|
|
|
+EXPORT_SYMBOL(mb_cache_entry_delete_block);
|
|
|
|
|
|
-
|
|
|
-/*
|
|
|
- * mb_cache_destroy()
|
|
|
+/* mb_cache_entry_touch - cache entry got used
|
|
|
+ * @cache - cache the entry belongs to
|
|
|
+ * @entry - entry that got used
|
|
|
*
|
|
|
- * 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.
|
|
|
+ * Marks entry as used to give hit higher chances of surviving in cache.
|
|
|
*/
|
|
|
-void
|
|
|
-mb_cache_destroy(struct mb_cache *cache)
|
|
|
+void mb_cache_entry_touch(struct mb_cache *cache,
|
|
|
+ struct mb_cache_entry *entry)
|
|
|
{
|
|
|
- LIST_HEAD(free_list);
|
|
|
- struct mb_cache_entry *ce, *tmp;
|
|
|
-
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- list_for_each_entry_safe(ce, tmp, &mb_cache_lru_list, e_lru_list) {
|
|
|
- if (ce->e_cache == cache)
|
|
|
- list_move_tail(&ce->e_lru_list, &free_list);
|
|
|
- }
|
|
|
- list_del(&cache->c_cache_list);
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
-
|
|
|
- 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);
|
|
|
- }
|
|
|
-
|
|
|
- if (atomic_read(&cache->c_entry_count) > 0) {
|
|
|
- mb_error("cache %s: %d orphaned entries",
|
|
|
- cache->c_name,
|
|
|
- atomic_read(&cache->c_entry_count));
|
|
|
- }
|
|
|
-
|
|
|
- if (list_empty(&mb_cache_list)) {
|
|
|
- kmem_cache_destroy(mb_cache_kmem_cache);
|
|
|
- mb_cache_kmem_cache = NULL;
|
|
|
- }
|
|
|
- kfree(cache->c_index_hash);
|
|
|
- kfree(cache->c_block_hash);
|
|
|
- kfree(cache);
|
|
|
+ entry->e_referenced = 1;
|
|
|
}
|
|
|
+EXPORT_SYMBOL(mb_cache_entry_touch);
|
|
|
|
|
|
-/*
|
|
|
- * 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 *
|
|
|
-mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
|
|
|
+static unsigned long mb_cache_count(struct shrinker *shrink,
|
|
|
+ struct shrink_control *sc)
|
|
|
{
|
|
|
- struct mb_cache_entry *ce;
|
|
|
-
|
|
|
- if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) {
|
|
|
- struct list_head *l;
|
|
|
-
|
|
|
- l = &mb_cache_lru_list;
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- 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;
|
|
|
- }
|
|
|
- }
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
- }
|
|
|
+ struct mb_cache *cache = container_of(shrink, struct mb_cache,
|
|
|
+ c_shrink);
|
|
|
|
|
|
- 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:
|
|
|
- ce->e_block_hash_p = &cache->c_block_hash[0];
|
|
|
- ce->e_index_hash_p = &cache->c_index_hash[0];
|
|
|
- ce->e_used = 1 + MB_CACHE_WRITER;
|
|
|
- return ce;
|
|
|
+ return cache->c_entry_count;
|
|
|
}
|
|
|
|
|
|
-
|
|
|
-/*
|
|
|
- * 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
|
|
|
- * @key: lookup key
|
|
|
- */
|
|
|
-int
|
|
|
-mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
|
|
|
- sector_t block, unsigned int key)
|
|
|
+/* Shrink number of entries in cache */
|
|
|
+static unsigned long mb_cache_shrink(struct mb_cache *cache,
|
|
|
+ unsigned int nr_to_scan)
|
|
|
{
|
|
|
- struct mb_cache *cache = ce->e_cache;
|
|
|
- unsigned int bucket;
|
|
|
- struct hlist_bl_node *l;
|
|
|
- struct hlist_bl_head *block_hash_p;
|
|
|
- struct hlist_bl_head *index_hash_p;
|
|
|
- struct mb_cache_entry *lce;
|
|
|
-
|
|
|
- mb_assert(ce);
|
|
|
- bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
|
|
|
- cache->c_bucket_bits);
|
|
|
- block_hash_p = &cache->c_block_hash[bucket];
|
|
|
- hlist_bl_lock(block_hash_p);
|
|
|
- hlist_bl_for_each_entry(lce, l, block_hash_p, e_block_list) {
|
|
|
- if (lce->e_bdev == bdev && lce->e_block == block) {
|
|
|
- hlist_bl_unlock(block_hash_p);
|
|
|
- return -EBUSY;
|
|
|
+ struct mb_cache_entry *entry;
|
|
|
+ struct hlist_bl_head *head;
|
|
|
+ unsigned int shrunk = 0;
|
|
|
+
|
|
|
+ spin_lock(&cache->c_list_lock);
|
|
|
+ while (nr_to_scan-- && !list_empty(&cache->c_list)) {
|
|
|
+ entry = list_first_entry(&cache->c_list,
|
|
|
+ struct mb_cache_entry, e_list);
|
|
|
+ if (entry->e_referenced) {
|
|
|
+ entry->e_referenced = 0;
|
|
|
+ list_move_tail(&cache->c_list, &entry->e_list);
|
|
|
+ continue;
|
|
|
}
|
|
|
+ list_del_init(&entry->e_list);
|
|
|
+ cache->c_entry_count--;
|
|
|
+ /*
|
|
|
+ * We keep LRU list reference so that entry doesn't go away
|
|
|
+ * from under us.
|
|
|
+ */
|
|
|
+ spin_unlock(&cache->c_list_lock);
|
|
|
+ head = mb_cache_entry_head(cache, entry->e_key);
|
|
|
+ hlist_bl_lock(head);
|
|
|
+ if (!hlist_bl_unhashed(&entry->e_hash_list)) {
|
|
|
+ hlist_bl_del_init(&entry->e_hash_list);
|
|
|
+ atomic_dec(&entry->e_refcnt);
|
|
|
+ }
|
|
|
+ hlist_bl_unlock(head);
|
|
|
+ if (mb_cache_entry_put(cache, entry))
|
|
|
+ shrunk++;
|
|
|
+ cond_resched();
|
|
|
+ spin_lock(&cache->c_list_lock);
|
|
|
}
|
|
|
- mb_assert(!__mb_cache_entry_is_block_hashed(ce));
|
|
|
- __mb_cache_entry_unhash_block(ce);
|
|
|
- __mb_cache_entry_unhash_index(ce);
|
|
|
- ce->e_bdev = bdev;
|
|
|
- ce->e_block = block;
|
|
|
- ce->e_block_hash_p = block_hash_p;
|
|
|
- ce->e_index.o_key = key;
|
|
|
- hlist_bl_add_head(&ce->e_block_list, block_hash_p);
|
|
|
- hlist_bl_unlock(block_hash_p);
|
|
|
- bucket = hash_long(key, cache->c_bucket_bits);
|
|
|
- index_hash_p = &cache->c_index_hash[bucket];
|
|
|
- hlist_bl_lock(index_hash_p);
|
|
|
- ce->e_index_hash_p = index_hash_p;
|
|
|
- hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
|
|
|
- hlist_bl_unlock(index_hash_p);
|
|
|
- return 0;
|
|
|
-}
|
|
|
+ spin_unlock(&cache->c_list_lock);
|
|
|
|
|
|
+ return shrunk;
|
|
|
+}
|
|
|
|
|
|
-/*
|
|
|
- * 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)
|
|
|
+static unsigned long mb_cache_scan(struct shrinker *shrink,
|
|
|
+ struct shrink_control *sc)
|
|
|
{
|
|
|
- __mb_cache_entry_release(ce);
|
|
|
+ int nr_to_scan = sc->nr_to_scan;
|
|
|
+ struct mb_cache *cache = container_of(shrink, struct mb_cache,
|
|
|
+ c_shrink);
|
|
|
+ return mb_cache_shrink(cache, nr_to_scan);
|
|
|
}
|
|
|
|
|
|
+/* We shrink 1/X of the cache when we have too many entries in it */
|
|
|
+#define SHRINK_DIVISOR 16
|
|
|
|
|
|
-/*
|
|
|
- * mb_cache_entry_free()
|
|
|
- *
|
|
|
- */
|
|
|
-void
|
|
|
-mb_cache_entry_free(struct mb_cache_entry *ce)
|
|
|
+static void mb_cache_shrink_worker(struct work_struct *work)
|
|
|
{
|
|
|
- mb_assert(ce);
|
|
|
- mb_assert(list_empty(&ce->e_lru_list));
|
|
|
- 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);
|
|
|
+ struct mb_cache *cache = container_of(work, struct mb_cache,
|
|
|
+ c_shrink_work);
|
|
|
+ mb_cache_shrink(cache, cache->c_max_entries / SHRINK_DIVISOR);
|
|
|
}
|
|
|
|
|
|
-
|
|
|
/*
|
|
|
- * mb_cache_entry_get()
|
|
|
+ * mb_cache_create - create cache
|
|
|
+ * @bucket_bits: log2 of the hash table size
|
|
|
*
|
|
|
- * 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").
|
|
|
+ * Create cache for keys with 2^bucket_bits hash entries.
|
|
|
*/
|
|
|
-struct mb_cache_entry *
|
|
|
-mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
|
|
|
- sector_t block)
|
|
|
+struct mb_cache *mb_cache_create(int bucket_bits)
|
|
|
{
|
|
|
- unsigned int bucket;
|
|
|
- struct hlist_bl_node *l;
|
|
|
- struct mb_cache_entry *ce;
|
|
|
- struct hlist_bl_head *block_hash_p;
|
|
|
-
|
|
|
- bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
|
|
|
- cache->c_bucket_bits);
|
|
|
- block_hash_p = &cache->c_block_hash[bucket];
|
|
|
- /* First serialize access to the block corresponding hash chain. */
|
|
|
- hlist_bl_lock(block_hash_p);
|
|
|
- hlist_bl_for_each_entry(ce, l, block_hash_p, e_block_list) {
|
|
|
- mb_assert(ce->e_block_hash_p == block_hash_p);
|
|
|
- if (ce->e_bdev == bdev && ce->e_block == block) {
|
|
|
- /*
|
|
|
- * 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);
|
|
|
+ struct mb_cache *cache;
|
|
|
+ int bucket_count = 1 << bucket_bits;
|
|
|
+ int i;
|
|
|
|
|
|
- if (!list_empty(&ce->e_lru_list)) {
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- list_del_init(&ce->e_lru_list);
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
- }
|
|
|
- if (!__mb_cache_entry_is_block_hashed(ce)) {
|
|
|
- __mb_cache_entry_release(ce);
|
|
|
- return NULL;
|
|
|
- }
|
|
|
- return ce;
|
|
|
- }
|
|
|
+ if (!try_module_get(THIS_MODULE))
|
|
|
+ return NULL;
|
|
|
+
|
|
|
+ cache = kzalloc(sizeof(struct mb_cache), GFP_KERNEL);
|
|
|
+ if (!cache)
|
|
|
+ goto err_out;
|
|
|
+ cache->c_bucket_bits = bucket_bits;
|
|
|
+ cache->c_max_entries = bucket_count << 4;
|
|
|
+ INIT_LIST_HEAD(&cache->c_list);
|
|
|
+ spin_lock_init(&cache->c_list_lock);
|
|
|
+ cache->c_hash = kmalloc(bucket_count * sizeof(struct hlist_bl_head),
|
|
|
+ GFP_KERNEL);
|
|
|
+ if (!cache->c_hash) {
|
|
|
+ kfree(cache);
|
|
|
+ goto err_out;
|
|
|
}
|
|
|
- hlist_bl_unlock(block_hash_p);
|
|
|
- return NULL;
|
|
|
-}
|
|
|
+ for (i = 0; i < bucket_count; i++)
|
|
|
+ INIT_HLIST_BL_HEAD(&cache->c_hash[i]);
|
|
|
|
|
|
-#if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
|
|
|
+ cache->c_shrink.count_objects = mb_cache_count;
|
|
|
+ cache->c_shrink.scan_objects = mb_cache_scan;
|
|
|
+ cache->c_shrink.seeks = DEFAULT_SEEKS;
|
|
|
+ register_shrinker(&cache->c_shrink);
|
|
|
|
|
|
-static struct mb_cache_entry *
|
|
|
-__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head,
|
|
|
- struct block_device *bdev, unsigned int key)
|
|
|
-{
|
|
|
+ INIT_WORK(&cache->c_shrink_work, mb_cache_shrink_worker);
|
|
|
|
|
|
- /* The index hash chain is alredy acquire by caller. */
|
|
|
- while (l != NULL) {
|
|
|
- struct mb_cache_entry *ce =
|
|
|
- hlist_bl_entry(l, struct mb_cache_entry,
|
|
|
- e_index.o_list);
|
|
|
- mb_assert(ce->e_index_hash_p == head);
|
|
|
- if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
|
|
|
- /*
|
|
|
- * 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++;
|
|
|
- /* Incrementing before holding the lock gives readers
|
|
|
- priority over writers. */
|
|
|
- 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)) {
|
|
|
- spin_lock(&mb_cache_spinlock);
|
|
|
- list_del_init(&ce->e_lru_list);
|
|
|
- spin_unlock(&mb_cache_spinlock);
|
|
|
- }
|
|
|
- if (!__mb_cache_entry_is_block_hashed(ce)) {
|
|
|
- __mb_cache_entry_release(ce);
|
|
|
- return ERR_PTR(-EAGAIN);
|
|
|
- }
|
|
|
- return ce;
|
|
|
- }
|
|
|
- l = l->next;
|
|
|
- }
|
|
|
- hlist_bl_unlock(head);
|
|
|
+ return cache;
|
|
|
+
|
|
|
+err_out:
|
|
|
+ module_put(THIS_MODULE);
|
|
|
return NULL;
|
|
|
}
|
|
|
-
|
|
|
+EXPORT_SYMBOL(mb_cache_create);
|
|
|
|
|
|
/*
|
|
|
- * mb_cache_entry_find_first()
|
|
|
- *
|
|
|
- * Find the first cache entry on a given device with a certain key in
|
|
|
- * an additional index. Additional matches can be found with
|
|
|
- * mb_cache_entry_find_next(). Returns NULL if no match was found. The
|
|
|
- * returned cache entry is locked for shared access ("multiple readers").
|
|
|
+ * mb_cache_destroy - destroy cache
|
|
|
+ * @cache: the cache to destroy
|
|
|
*
|
|
|
- * @cache: the cache to search
|
|
|
- * @bdev: the device the cache entry should belong to
|
|
|
- * @key: the key in the index
|
|
|
+ * Free all entries in cache and cache itself. Caller must make sure nobody
|
|
|
+ * (except shrinker) can reach @cache when calling this.
|
|
|
*/
|
|
|
-struct mb_cache_entry *
|
|
|
-mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
|
|
|
- unsigned int key)
|
|
|
+void mb_cache_destroy(struct mb_cache *cache)
|
|
|
{
|
|
|
- unsigned int bucket = hash_long(key, cache->c_bucket_bits);
|
|
|
- struct hlist_bl_node *l;
|
|
|
- struct mb_cache_entry *ce = NULL;
|
|
|
- struct hlist_bl_head *index_hash_p;
|
|
|
-
|
|
|
- index_hash_p = &cache->c_index_hash[bucket];
|
|
|
- hlist_bl_lock(index_hash_p);
|
|
|
- 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);
|
|
|
- } else
|
|
|
- hlist_bl_unlock(index_hash_p);
|
|
|
- return ce;
|
|
|
-}
|
|
|
+ struct mb_cache_entry *entry, *next;
|
|
|
|
|
|
+ unregister_shrinker(&cache->c_shrink);
|
|
|
|
|
|
-/*
|
|
|
- * 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
|
|
|
- * @bdev: the device the cache entry should belong to
|
|
|
- * @key: the key in the index
|
|
|
- */
|
|
|
-struct mb_cache_entry *
|
|
|
-mb_cache_entry_find_next(struct mb_cache_entry *prev,
|
|
|
- struct block_device *bdev, unsigned int key)
|
|
|
-{
|
|
|
- struct mb_cache *cache = prev->e_cache;
|
|
|
- unsigned int bucket = hash_long(key, cache->c_bucket_bits);
|
|
|
- struct hlist_bl_node *l;
|
|
|
- struct mb_cache_entry *ce;
|
|
|
- struct hlist_bl_head *index_hash_p;
|
|
|
-
|
|
|
- index_hash_p = &cache->c_index_hash[bucket];
|
|
|
- mb_assert(prev->e_index_hash_p == index_hash_p);
|
|
|
- hlist_bl_lock(index_hash_p);
|
|
|
- mb_assert(!hlist_bl_empty(index_hash_p));
|
|
|
- l = prev->e_index.o_list.next;
|
|
|
- ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
|
|
|
- __mb_cache_entry_release(prev);
|
|
|
- return ce;
|
|
|
+ /*
|
|
|
+ * We don't bother with any locking. Cache must not be used at this
|
|
|
+ * point.
|
|
|
+ */
|
|
|
+ list_for_each_entry_safe(entry, next, &cache->c_list, e_list) {
|
|
|
+ if (!hlist_bl_unhashed(&entry->e_hash_list)) {
|
|
|
+ hlist_bl_del_init(&entry->e_hash_list);
|
|
|
+ atomic_dec(&entry->e_refcnt);
|
|
|
+ } else
|
|
|
+ WARN_ON(1);
|
|
|
+ list_del(&entry->e_list);
|
|
|
+ WARN_ON(atomic_read(&entry->e_refcnt) != 1);
|
|
|
+ mb_cache_entry_put(cache, entry);
|
|
|
+ }
|
|
|
+ kfree(cache->c_hash);
|
|
|
+ kfree(cache);
|
|
|
+ module_put(THIS_MODULE);
|
|
|
}
|
|
|
+EXPORT_SYMBOL(mb_cache_destroy);
|
|
|
|
|
|
-#endif /* !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0) */
|
|
|
-
|
|
|
-static int __init init_mbcache(void)
|
|
|
+static int __init mbcache_init(void)
|
|
|
{
|
|
|
- register_shrinker(&mb_cache_shrinker);
|
|
|
+ mb_entry_cache = kmem_cache_create("mbcache",
|
|
|
+ sizeof(struct mb_cache_entry), 0,
|
|
|
+ SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
|
|
|
+ BUG_ON(!mb_entry_cache);
|
|
|
return 0;
|
|
|
}
|
|
|
|
|
|
-static void __exit exit_mbcache(void)
|
|
|
+static void __exit mbcache_exit(void)
|
|
|
{
|
|
|
- unregister_shrinker(&mb_cache_shrinker);
|
|
|
+ kmem_cache_destroy(mb_entry_cache);
|
|
|
}
|
|
|
|
|
|
-module_init(init_mbcache)
|
|
|
-module_exit(exit_mbcache)
|
|
|
+module_init(mbcache_init)
|
|
|
+module_exit(mbcache_exit)
|
|
|
|
|
|
+MODULE_AUTHOR("Jan Kara <jack@suse.cz>");
|
|
|
+MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
|
|
|
+MODULE_LICENSE("GPL");
|
Linus Torvalds