mbcache: get rid of _e_hash_list_head

Get rid of field _e_hash_list_head in cache entries and add bit field
e_referenced instead.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/mbcache.c b/fs/mbcache.c
index 4241b63..903be15 100644 (file)
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -45,27 +45,10 @@ static struct kmem_cache *mb_entry_cache;
 static unsigned long mb_cache_shrink(struct mb_cache *cache,
                                     unsigned int nr_to_scan);
 
-static inline bool mb_cache_entry_referenced(struct mb_cache_entry *entry)
+static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache,
+                                                       u32 key)
 {
-       return entry->_e_hash_list_head & 1;
-}
-
-static inline void mb_cache_entry_set_referenced(struct mb_cache_entry *entry)
-{
-       entry->_e_hash_list_head |= 1;
-}
-
-static inline void mb_cache_entry_clear_referenced(
-                                       struct mb_cache_entry *entry)
-{
-       entry->_e_hash_list_head &= ~1;
-}
-
-static inline struct hlist_bl_head *mb_cache_entry_head(
-                                       struct mb_cache_entry *entry)
-{
-       return (struct hlist_bl_head *)
-                       (entry->_e_hash_list_head & ~1);
+       return &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
 }
 
 /*
@@ -108,8 +91,7 @@ int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
        atomic_set(&entry->e_refcnt, 1);
        entry->e_key = key;
        entry->e_block = block;
-       head = &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
-       entry->_e_hash_list_head = (unsigned long)head;
+       head = mb_cache_entry_head(cache, key);
        hlist_bl_lock(head);
        hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {
                if (dup->e_key == key && dup->e_block == block) {
@@ -146,10 +128,7 @@ static struct mb_cache_entry *__entry_find(struct mb_cache *cache,
        struct hlist_bl_node *node;
        struct hlist_bl_head *head;
 
-       if (entry)
-               head = mb_cache_entry_head(entry);
-       else
-               head = &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
+       head = mb_cache_entry_head(cache, key);
        hlist_bl_lock(head);
        if (entry && !hlist_bl_unhashed(&entry->e_hash_list))
                node = entry->e_hash_list.next;
@@ -219,7 +198,7 @@ void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
        struct hlist_bl_head *head;
        struct mb_cache_entry *entry;
 
-       head = &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
+       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) {
@@ -250,7 +229,7 @@ EXPORT_SYMBOL(mb_cache_entry_delete_block);
 void mb_cache_entry_touch(struct mb_cache *cache,
                          struct mb_cache_entry *entry)
 {
-       mb_cache_entry_set_referenced(entry);
+       entry->e_referenced = 1;
 }
 EXPORT_SYMBOL(mb_cache_entry_touch);
 
@@ -275,8 +254,8 @@ static unsigned long mb_cache_shrink(struct mb_cache *cache,
        while (nr_to_scan-- && !list_empty(&cache->c_list)) {
                entry = list_first_entry(&cache->c_list,
                                         struct mb_cache_entry, e_list);
-               if (mb_cache_entry_referenced(entry)) {
-                       mb_cache_entry_clear_referenced(entry);
+               if (entry->e_referenced) {
+                       entry->e_referenced = 0;
                        list_move_tail(&cache->c_list, &entry->e_list);
                        continue;
                }
@@ -287,7 +266,7 @@ static unsigned long mb_cache_shrink(struct mb_cache *cache,
                 * from under us.
                 */
                spin_unlock(&cache->c_list_lock);
-               head = mb_cache_entry_head(entry);
+               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);

diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
index a74a1f3..607e696 100644 (file)
--- a/include/linux/mbcache.h
+++ b/include/linux/mbcache.h
@@ -12,18 +12,14 @@ struct mb_cache;
 struct mb_cache_entry {
        /* List of entries in cache - protected by cache->c_list_lock */
        struct list_head        e_list;
-       /* Hash table list - protected by bitlock in e_hash_list_head */
+       /* Hash table list - protected by hash chain bitlock */
        struct hlist_bl_node    e_hash_list;
        atomic_t                e_refcnt;
        /* Key in hash - stable during lifetime of the entry */
        u32                     e_key;
+       u32                     e_referenced:1;
        /* Block number of hashed block - stable during lifetime of the entry */
        sector_t                e_block;
-       /*
-        * Head of hash list (for list bit lock) - stable. Combined with
-        * referenced bit of entry
-        */
-       unsigned long           _e_hash_list_head;
 };
 
 struct mb_cache *mb_cache_create(int bucket_bits);