get-rid-of-e_hash_list_head

   1 mbcache: get rid of _e_hash_list_head
   2
   3 From: Andreas Gruenbacher <agruenba@redhat.com>
   4
   5 Get rid of field _e_hash_list_head in cache entries and add bit field
   6 e_referenced instead.
   7
   8 Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
   9 Signed-off-by: Jan Kara <jack@suse.cz>
  10 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  11 ---
  12  fs/mbcache.c            | 41 ++++++++++-------------------------------
  13  include/linux/mbcache.h |  8 ++------
  14  2 files changed, 12 insertions(+), 37 deletions(-)
  15
  16 diff --git a/fs/mbcache.c b/fs/mbcache.c
  17 index 4241b633f155..903be151dcfe 100644
  18 --- a/fs/mbcache.c
  19 +++ b/fs/mbcache.c
  20 @@ -45,27 +45,10 @@ static struct kmem_cache *mb_entry_cache;
  21  static unsigned long mb_cache_shrink(struct mb_cache *cache,
  22                                      unsigned int nr_to_scan);
  23
  24 -static inline bool mb_cache_entry_referenced(struct mb_cache_entry *entry)
  25 +static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache,
  26 +                                                       u32 key)
  27  {
  28 -       return entry->_e_hash_list_head & 1;
  29 -}
  30 -
  31 -static inline void mb_cache_entry_set_referenced(struct mb_cache_entry *entry)
  32 -{
  33 -       entry->_e_hash_list_head |= 1;
  34 -}
  35 -
  36 -static inline void mb_cache_entry_clear_referenced(
  37 -                                       struct mb_cache_entry *entry)
  38 -{
  39 -       entry->_e_hash_list_head &= ~1;
  40 -}
  41 -
  42 -static inline struct hlist_bl_head *mb_cache_entry_head(
  43 -                                       struct mb_cache_entry *entry)
  44 -{
  45 -       return (struct hlist_bl_head *)
  46 -                       (entry->_e_hash_list_head & ~1);
  47 +       return &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
  48  }
  49
  50  /*
  51 @@ -108,8 +91,7 @@ int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
  52         atomic_set(&entry->e_refcnt, 1);
  53         entry->e_key = key;
  54         entry->e_block = block;
  55 -       head = &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
  56 -       entry->_e_hash_list_head = (unsigned long)head;
  57 +       head = mb_cache_entry_head(cache, key);
  58         hlist_bl_lock(head);
  59         hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {
  60                 if (dup->e_key == key && dup->e_block == block) {
  61 @@ -146,10 +128,7 @@ static struct mb_cache_entry *__entry_find(struct mb_cache *cache,
  62         struct hlist_bl_node *node;
  63         struct hlist_bl_head *head;
  64
  65 -       if (entry)
  66 -               head = mb_cache_entry_head(entry);
  67 -       else
  68 -               head = &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
  69 +       head = mb_cache_entry_head(cache, key);
  70         hlist_bl_lock(head);
  71         if (entry && !hlist_bl_unhashed(&entry->e_hash_list))
  72                 node = entry->e_hash_list.next;
  73 @@ -219,7 +198,7 @@ void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
  74         struct hlist_bl_head *head;
  75         struct mb_cache_entry *entry;
  76
  77 -       head = &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
  78 +       head = mb_cache_entry_head(cache, key);
  79         hlist_bl_lock(head);
  80         hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
  81                 if (entry->e_key == key && entry->e_block == block) {
  82 @@ -250,7 +229,7 @@ EXPORT_SYMBOL(mb_cache_entry_delete_block);
  83  void mb_cache_entry_touch(struct mb_cache *cache,
  84                           struct mb_cache_entry *entry)
  85  {
  86 -       mb_cache_entry_set_referenced(entry);
  87 +       entry->e_referenced = 1;
  88  }
  89  EXPORT_SYMBOL(mb_cache_entry_touch);
  90
  91 @@ -275,8 +254,8 @@ static unsigned long mb_cache_shrink(struct mb_cache *cache,
  92         while (nr_to_scan-- && !list_empty(&cache->c_list)) {
  93                 entry = list_first_entry(&cache->c_list,
  94                                          struct mb_cache_entry, e_list);
  95 -               if (mb_cache_entry_referenced(entry)) {
  96 -                       mb_cache_entry_clear_referenced(entry);
  97 +               if (entry->e_referenced) {
  98 +                       entry->e_referenced = 0;
  99                         list_move_tail(&cache->c_list, &entry->e_list);
 100                         continue;
 101                 }
 102 @@ -287,7 +266,7 @@ static unsigned long mb_cache_shrink(struct mb_cache *cache,
 103                  * from under us.
 104                  */
 105                 spin_unlock(&cache->c_list_lock);
 106 -               head = mb_cache_entry_head(entry);
 107 +               head = mb_cache_entry_head(cache, entry->e_key);
 108                 hlist_bl_lock(head);
 109                 if (!hlist_bl_unhashed(&entry->e_hash_list)) {
 110                         hlist_bl_del_init(&entry->e_hash_list);
 111 diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
 112 index a74a1f3082fb..607e6968542e 100644
 113 --- a/include/linux/mbcache.h
 114 +++ b/include/linux/mbcache.h
 115 @@ -12,18 +12,14 @@ struct mb_cache;
 116  struct mb_cache_entry {
 117         /* List of entries in cache - protected by cache->c_list_lock */
 118         struct list_head        e_list;
 119 -       /* Hash table list - protected by bitlock in e_hash_list_head */
 120 +       /* Hash table list - protected by hash chain bitlock */
 121         struct hlist_bl_node    e_hash_list;
 122         atomic_t                e_refcnt;
 123         /* Key in hash - stable during lifetime of the entry */
 124         u32                     e_key;
 125 +       u32                     e_referenced:1;
 126         /* Block number of hashed block - stable during lifetime of the entry */
 127         sector_t                e_block;
 128 -       /*
 129 -        * Head of hash list (for list bit lock) - stable. Combined with
 130 -        * referenced bit of entry
 131 -        */
 132 -       unsigned long           _e_hash_list_head;
 133  };
 134
 135  struct mb_cache *mb_cache_create(int bucket_bits);
 136 --
 137 2.6.2
 138
 139