mbcache: Remove unused features

The mbcache code was written to support a variable number of indexes,
but all the existing users use exactly one index.  Simplify to code to
support only that case.

There are also no users of the cache entry free operation, and none of
the users keep extra data in cache entries.  Remove those features as
well.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 40 insertions, 101 deletions

diff --git a/fs/mbcache.c b/fs/mbcache.c
index e28f21b95344..8a2cbd823079 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -79,15 +79,11 @@ EXPORT_SYMBOL(mb_cache_entry_find_next);
 struct mb_cache {
         struct list_head                c_cache_list;
         const char                      *c_name;
-        struct mb_cache_op              c_op;
         atomic_t                        c_entry_count;
         int                             c_bucket_bits;
-#ifndef MB_CACHE_INDEXES_COUNT
-        int                             c_indexes_count;
-#endif
-        struct kmem_cache                       *c_entry_cache;
+        struct kmem_cache               *c_entry_cache;
         struct list_head                *c_block_hash;
-        struct list_head                *c_indexes_hash[0];
+        struct list_head                *c_index_hash;
 };
 
 
@@ -101,16 +97,6 @@ static LIST_HEAD(mb_cache_list);
 static LIST_HEAD(mb_cache_lru_list);
 static DEFINE_SPINLOCK(mb_cache_spinlock);
 
-static inline int
-mb_cache_indexes(struct mb_cache *cache)
-{
-#ifdef MB_CACHE_INDEXES_COUNT
-        return MB_CACHE_INDEXES_COUNT;
-#else
-        return cache->c_indexes_count;
-#endif
-}
-
 /*
  * What the mbcache registers as to get shrunk dynamically.
  */
@@ -132,12 +118,9 @@ __mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
 static void
 __mb_cache_entry_unhash(struct mb_cache_entry *ce)
 {
-        int n;
-
         if (__mb_cache_entry_is_hashed(ce)) {
                 list_del_init(&ce->e_block_list);
-                for (n=0; n<mb_cache_indexes(ce->e_cache); n++)
-                        list_del(&ce->e_indexes[n].o_list);
+                list_del(&ce->e_index.o_list);
         }
 }
 
@@ -148,16 +131,8 @@ __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
         struct mb_cache *cache = ce->e_cache;
 
         mb_assert(!(ce->e_used || ce->e_queued));
-        if (cache->c_op.free && cache->c_op.free(ce, gfp_mask)) {
-                /* free failed -- put back on the lru list
-                   for freeing later. */
-                spin_lock(&mb_cache_spinlock);
-                list_add(&ce->e_lru_list, &mb_cache_lru_list);
-                spin_unlock(&mb_cache_spinlock);
-        } else {
-                kmem_cache_free(cache->c_entry_cache, ce);
-                atomic_dec(&cache->c_entry_count);
-        }
+        kmem_cache_free(cache->c_entry_cache, ce);
+        atomic_dec(&cache->c_entry_count);
 }
 
 
@@ -243,72 +218,49 @@ out:
  * memory was available.
  *
  * @name: name of the cache (informal)
- * @cache_op: contains the callback called when freeing a cache entry
- * @entry_size: The size of a cache entry, including
- *              struct mb_cache_entry
- * @indexes_count: number of additional indexes in the cache. Must equal
- *                 MB_CACHE_INDEXES_COUNT if the number of indexes is
- *                 hardwired.
  * @bucket_bits: log2(number of hash buckets)
  */
 struct mb_cache *
-mb_cache_create(const char *name, struct mb_cache_op *cache_op,
-                size_t entry_size, int indexes_count, int bucket_bits)
+mb_cache_create(const char *name, int bucket_bits)
 {
-        int m=0, n, bucket_count = 1 << bucket_bits;
+        int n, bucket_count = 1 << bucket_bits;
         struct mb_cache *cache = NULL;
 
-        if(entry_size < sizeof(struct mb_cache_entry) +
-           indexes_count * sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]))
-                return NULL;
-
-        cache = kmalloc(sizeof(struct mb_cache) +
-                        indexes_count * sizeof(struct list_head), GFP_KERNEL);
+        cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL);
         if (!cache)
-                goto fail;
+                return NULL;
         cache->c_name = name;
-        cache->c_op.free = NULL;
-        if (cache_op)
-                cache->c_op.free = cache_op->free;
         atomic_set(&cache->c_entry_count, 0);
         cache->c_bucket_bits = bucket_bits;
-#ifdef MB_CACHE_INDEXES_COUNT
-        mb_assert(indexes_count == MB_CACHE_INDEXES_COUNT);
-#else
-        cache->c_indexes_count = indexes_count;
-#endif
         cache->c_block_hash = kmalloc(bucket_count * sizeof(struct list_head),
                                       GFP_KERNEL);
         if (!cache->c_block_hash)
                 goto fail;
         for (n=0; n<bucket_count; n++)
                 INIT_LIST_HEAD(&cache->c_block_hash[n]);
-        for (m=0; m<indexes_count; m++) {
-                cache->c_indexes_hash[m] = kmalloc(bucket_count *
-                                                 sizeof(struct list_head),
-                                                 GFP_KERNEL);
-                if (!cache->c_indexes_hash[m])
-                        goto fail;
-                for (n=0; n<bucket_count; n++)
-                        INIT_LIST_HEAD(&cache->c_indexes_hash[m][n]);
-        }
-        cache->c_entry_cache = kmem_cache_create(name, entry_size, 0,
+        cache->c_index_hash = kmalloc(bucket_count * sizeof(struct list_head),
+                                      GFP_KERNEL);
+        if (!cache->c_index_hash)
+                goto fail;
+        for (n=0; n<bucket_count; n++)
+                INIT_LIST_HEAD(&cache->c_index_hash[n]);
+        cache->c_entry_cache = kmem_cache_create(name,
+                sizeof(struct mb_cache_entry), 0,
                 SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
         if (!cache->c_entry_cache)
-                goto fail;
+                goto fail2;
 
         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:
-        if (cache) {
-                while (--m >= 0)
-                        kfree(cache->c_indexes_hash[m]);
-                kfree(cache->c_block_hash);
-                kfree(cache);
-        }
+        kfree(cache->c_block_hash);
+        kfree(cache);
         return NULL;
 }
 
@@ -357,7 +309,6 @@ mb_cache_destroy(struct mb_cache *cache)
 {
         LIST_HEAD(free_list);
         struct list_head *l, *ltmp;
-        int n;
 
         spin_lock(&mb_cache_spinlock);
         list_for_each_safe(l, ltmp, &mb_cache_lru_list) {
@@ -384,8 +335,7 @@ mb_cache_destroy(struct mb_cache *cache)
 
         kmem_cache_destroy(cache->c_entry_cache);
 
-        for (n=0; n < mb_cache_indexes(cache); n++)
-                kfree(cache->c_indexes_hash[n]);
+        kfree(cache->c_index_hash);
         kfree(cache->c_block_hash);
         kfree(cache);
 }
@@ -429,17 +379,16 @@ mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
  *
  * @bdev: device the cache entry belongs to
  * @block: block number
- * @keys: array of additional keys. There must be indexes_count entries
- *        in the array (as specified when creating the cache).
+ * @key: lookup key
  */
 int
 mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
-                      sector_t block, unsigned int keys[])
+                      sector_t block, unsigned int key)
 {
         struct mb_cache *cache = ce->e_cache;
         unsigned int bucket;
         struct list_head *l;
-        int error = -EBUSY, n;
+        int error = -EBUSY;
 
         bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), 
                            cache->c_bucket_bits);
@@ -454,12 +403,9 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
         ce->e_bdev = bdev;
         ce->e_block = block;
         list_add(&ce->e_block_list, &cache->c_block_hash[bucket]);
-        for (n=0; n<mb_cache_indexes(cache); n++) {
-                ce->e_indexes[n].o_key = keys[n];
-                bucket = hash_long(keys[n], cache->c_bucket_bits);
-                list_add(&ce->e_indexes[n].o_list,
-                         &cache->c_indexes_hash[n][bucket]);
-        }
+        ce->e_index.o_key = key;
+        bucket = hash_long(key, cache->c_bucket_bits);
+        list_add(&ce->e_index.o_list, &cache->c_index_hash[bucket]);
         error = 0;
 out:
         spin_unlock(&mb_cache_spinlock);
@@ -555,13 +501,12 @@ cleanup:
 
 static struct mb_cache_entry *
 __mb_cache_entry_find(struct list_head *l, struct list_head *head,
-                      int index, struct block_device *bdev, unsigned int key)
+                      struct block_device *bdev, unsigned int key)
 {
         while (l != head) {
                 struct mb_cache_entry *ce =
-                        list_entry(l, struct mb_cache_entry,
-                                   e_indexes[index].o_list);
-                if (ce->e_bdev == bdev && ce->e_indexes[index].o_key == key) {
+                        list_entry(l, struct mb_cache_entry, e_index.o_list);
+                if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
                         DEFINE_WAIT(wait);
 
                         if (!list_empty(&ce->e_lru_list))
@@ -603,23 +548,20 @@ __mb_cache_entry_find(struct list_head *l, struct list_head *head,
  * returned cache entry is locked for shared access ("multiple readers").
  *
  * @cache: the cache to search
- * @index: the number of the additonal index to search (0<=index<indexes_count)
  * @bdev: the device the cache entry should belong to
  * @key: the key in the index
  */
 struct mb_cache_entry *
-mb_cache_entry_find_first(struct mb_cache *cache, int index,
-                          struct block_device *bdev, unsigned int key)
+mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
+                          unsigned int key)
 {
         unsigned int bucket = hash_long(key, cache->c_bucket_bits);
         struct list_head *l;
         struct mb_cache_entry *ce;
 
-        mb_assert(index < mb_cache_indexes(cache));
         spin_lock(&mb_cache_spinlock);
-        l = cache->c_indexes_hash[index][bucket].next;
-        ce = __mb_cache_entry_find(l, &cache->c_indexes_hash[index][bucket],
-                                   index, bdev, key);
+        l = cache->c_index_hash[bucket].next;
+        ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
         spin_unlock(&mb_cache_spinlock);
         return ce;
 }
@@ -640,12 +582,11 @@ mb_cache_entry_find_first(struct mb_cache *cache, int index,
  * }
  *
  * @prev: The previous match
- * @index: the number of the additonal index to search (0<=index<indexes_count)
  * @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, int index,
+mb_cache_entry_find_next(struct mb_cache_entry *prev,
                          struct block_device *bdev, unsigned int key)
 {
         struct mb_cache *cache = prev->e_cache;
@@ -653,11 +594,9 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev, int index,
         struct list_head *l;
         struct mb_cache_entry *ce;
 
-        mb_assert(index < mb_cache_indexes(cache));
         spin_lock(&mb_cache_spinlock);
-        l = prev->e_indexes[index].o_list.next;
-        ce = __mb_cache_entry_find(l, &cache->c_indexes_hash[index][bucket],
-                                   index, bdev, key);
+        l = prev->e_index.o_list.next;
+        ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
         __mb_cache_entry_release_unlock(prev);
         return ce;
 }