change-block-and-index-hash-chain-to-hlist_bl_node

   1 fs/mbcache.c: change block and index hash chain to hlist_bl_node
   2
   3 From: T Makphaibulchoke <tmac@hp.com>
   4
   5 This patch changes each mb_cache's both block and index hash chains to
   6 use a hlist_bl_node, which contains a built-in lock.  This is the
   7 first step in decoupling of locks serializing accesses to mb_cache
   8 global data and each mb_cache_entry local data.
   9
  10 Signed-off-by: T. Makphaibulchoke <tmac@hp.com>
  11 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  12 ---
  13  fs/mbcache.c            | 117 ++++++++++++++++++++++++++++++++----------------
  14  include/linux/mbcache.h |  12 ++---
  15  2 files changed, 85 insertions(+), 44 deletions(-)
  16
  17 diff --git a/fs/mbcache.c b/fs/mbcache.c
  18 index e519e45..55db0da 100644
  19 --- a/fs/mbcache.c
  20 +++ b/fs/mbcache.c
  21 @@ -34,9 +34,9 @@
  22  #include <linux/mm.h>
  23  #include <linux/slab.h>
  24  #include <linux/sched.h>
  25 -#include <linux/init.h>
  26 +#include <linux/list_bl.h>
  27  #include <linux/mbcache.h>
  28 -
  29 +#include <linux/init.h>
  30
  31  #ifdef MB_CACHE_DEBUG
  32  # define mb_debug(f...) do { \
  33 @@ -87,21 +87,38 @@ static LIST_HEAD(mb_cache_lru_list);
  34  static DEFINE_SPINLOCK(mb_cache_spinlock);
  35
  36  static inline int
  37 -__mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
  38 +__mb_cache_entry_is_block_hashed(struct mb_cache_entry *ce)
  39  {
  40 -       return !list_empty(&ce->e_block_list);
  41 +       return !hlist_bl_unhashed(&ce->e_block_list);
  42  }
  43
  44
  45 -static void
  46 -__mb_cache_entry_unhash(struct mb_cache_entry *ce)
  47 +static inline void
  48 +__mb_cache_entry_unhash_block(struct mb_cache_entry *ce)
  49  {
  50 -       if (__mb_cache_entry_is_hashed(ce)) {
  51 -               list_del_init(&ce->e_block_list);
  52 -               list_del(&ce->e_index.o_list);
  53 -       }
  54 +       if (__mb_cache_entry_is_block_hashed(ce))
  55 +               hlist_bl_del_init(&ce->e_block_list);
  56 +}
  57 +
  58 +static inline int
  59 +__mb_cache_entry_is_index_hashed(struct mb_cache_entry *ce)
  60 +{
  61 +       return !hlist_bl_unhashed(&ce->e_index.o_list);
  62  }
  63
  64 +static inline void
  65 +__mb_cache_entry_unhash_index(struct mb_cache_entry *ce)
  66 +{
  67 +       if (__mb_cache_entry_is_index_hashed(ce))
  68 +               hlist_bl_del_init(&ce->e_index.o_list);
  69 +}
  70 +
  71 +static inline void
  72 +__mb_cache_entry_unhash(struct mb_cache_entry *ce)
  73 +{
  74 +       __mb_cache_entry_unhash_index(ce);
  75 +       __mb_cache_entry_unhash_block(ce);
  76 +}
  77
  78  static void
  79  __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
  80 @@ -125,7 +142,7 @@ __mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
  81                 ce->e_used -= MB_CACHE_WRITER;
  82         ce->e_used--;
  83         if (!(ce->e_used || ce->e_queued)) {
  84 -               if (!__mb_cache_entry_is_hashed(ce))
  85 +               if (!__mb_cache_entry_is_block_hashed(ce))
  86                         goto forget;
  87                 mb_assert(list_empty(&ce->e_lru_list));
  88                 list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
  89 @@ -221,18 +238,18 @@ mb_cache_create(const char *name, int bucket_bits)
  90         cache->c_name = name;
  91         atomic_set(&cache->c_entry_count, 0);
  92         cache->c_bucket_bits = bucket_bits;
  93 -       cache->c_block_hash = kmalloc(bucket_count * sizeof(struct list_head),
  94 -                                     GFP_KERNEL);
  95 +       cache->c_block_hash = kmalloc(bucket_count *
  96 +               sizeof(struct hlist_bl_head), GFP_KERNEL);
  97         if (!cache->c_block_hash)
  98                 goto fail;
  99         for (n=0; n<bucket_count; n++)
 100 -               INIT_LIST_HEAD(&cache->c_block_hash[n]);
 101 -       cache->c_index_hash = kmalloc(bucket_count * sizeof(struct list_head),
 102 -                                     GFP_KERNEL);
 103 +               INIT_HLIST_BL_HEAD(&cache->c_block_hash[n]);
 104 +       cache->c_index_hash = kmalloc(bucket_count *
 105 +               sizeof(struct hlist_bl_head), GFP_KERNEL);
 106         if (!cache->c_index_hash)
 107                 goto fail;
 108         for (n=0; n<bucket_count; n++)
 109 -               INIT_LIST_HEAD(&cache->c_index_hash[n]);
 110 +               INIT_HLIST_BL_HEAD(&cache->c_index_hash[n]);
 111         cache->c_entry_cache = kmem_cache_create(name,
 112                 sizeof(struct mb_cache_entry), 0,
 113                 SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
 114 @@ -364,10 +381,13 @@ mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
 115                         return NULL;
 116                 atomic_inc(&cache->c_entry_count);
 117                 INIT_LIST_HEAD(&ce->e_lru_list);
 118 -               INIT_LIST_HEAD(&ce->e_block_list);
 119 +               INIT_HLIST_BL_NODE(&ce->e_block_list);
 120 +               INIT_HLIST_BL_NODE(&ce->e_index.o_list);
 121                 ce->e_cache = cache;
 122                 ce->e_queued = 0;
 123         }
 124 +       ce->e_block_hash_p = &cache->c_block_hash[0];
 125 +       ce->e_index_hash_p = &cache->c_index_hash[0];
 126         ce->e_used = 1 + MB_CACHE_WRITER;
 127         return ce;
 128  }
 129 @@ -393,25 +413,32 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
 130  {
 131         struct mb_cache *cache = ce->e_cache;
 132         unsigned int bucket;
 133 -       struct list_head *l;
 134 +       struct hlist_bl_node *l;
 135         int error = -EBUSY;
 136 +       struct hlist_bl_head *block_hash_p;
 137 +       struct hlist_bl_head *index_hash_p;
 138 +       struct mb_cache_entry *lce;
 139
 140 +       mb_assert(ce);
 141         bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
 142                            cache->c_bucket_bits);
 143 +       block_hash_p = &cache->c_block_hash[bucket];
 144         spin_lock(&mb_cache_spinlock);
 145 -       list_for_each_prev(l, &cache->c_block_hash[bucket]) {
 146 -               struct mb_cache_entry *ce =
 147 -                       list_entry(l, struct mb_cache_entry, e_block_list);
 148 -               if (ce->e_bdev == bdev && ce->e_block == block)
 149 +       hlist_bl_for_each_entry(lce, l, block_hash_p, e_block_list) {
 150 +               if (lce->e_bdev == bdev && lce->e_block == block)
 151                         goto out;
 152         }
 153 +       mb_assert(!__mb_cache_entry_is_block_hashed(ce));
 154         __mb_cache_entry_unhash(ce);
 155         ce->e_bdev = bdev;
 156         ce->e_block = block;
 157 -       list_add(&ce->e_block_list, &cache->c_block_hash[bucket]);
 158 +       ce->e_block_hash_p = block_hash_p;
 159         ce->e_index.o_key = key;
 160         bucket = hash_long(key, cache->c_bucket_bits);
 161 -       list_add(&ce->e_index.o_list, &cache->c_index_hash[bucket]);
 162 +       index_hash_p = &cache->c_index_hash[bucket];
 163 +       ce->e_index_hash_p = index_hash_p;
 164 +       hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
 165 +       hlist_bl_add_head(&ce->e_block_list, block_hash_p);
 166         error = 0;
 167  out:
 168         spin_unlock(&mb_cache_spinlock);
 169 @@ -463,14 +490,16 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
 170                    sector_t block)
 171  {
 172         unsigned int bucket;
 173 -       struct list_head *l;
 174 +       struct hlist_bl_node *l;
 175         struct mb_cache_entry *ce;
 176 +       struct hlist_bl_head *block_hash_p;
 177
 178         bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
 179                            cache->c_bucket_bits);
 180 +       block_hash_p = &cache->c_block_hash[bucket];
 181         spin_lock(&mb_cache_spinlock);
 182 -       list_for_each(l, &cache->c_block_hash[bucket]) {
 183 -               ce = list_entry(l, struct mb_cache_entry, e_block_list);
 184 +       hlist_bl_for_each_entry(ce, l, block_hash_p, e_block_list) {
 185 +               mb_assert(ce->e_block_hash_p == block_hash_p);
 186                 if (ce->e_bdev == bdev && ce->e_block == block) {
 187                         DEFINE_WAIT(wait);
 188
 189 @@ -489,7 +518,7 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
 190                         finish_wait(&mb_cache_queue, &wait);
 191                         ce->e_used += 1 + MB_CACHE_WRITER;
 192
 193 -                       if (!__mb_cache_entry_is_hashed(ce)) {
 194 +                       if (!__mb_cache_entry_is_block_hashed(ce)) {
 195                                 __mb_cache_entry_release_unlock(ce);
 196                                 return NULL;
 197                         }
 198 @@ -506,12 +535,14 @@ cleanup:
 199  #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
 200
 201  static struct mb_cache_entry *
 202 -__mb_cache_entry_find(struct list_head *l, struct list_head *head,
 203 +__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head,
 204                       struct block_device *bdev, unsigned int key)
 205  {
 206 -       while (l != head) {
 207 +       while (l != NULL) {
 208                 struct mb_cache_entry *ce =
 209 -                       list_entry(l, struct mb_cache_entry, e_index.o_list);
 210 +                       hlist_bl_entry(l, struct mb_cache_entry,
 211 +                               e_index.o_list);
 212 +               mb_assert(ce->e_index_hash_p == head);
 213                 if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
 214                         DEFINE_WAIT(wait);
 215
 216 @@ -532,7 +563,7 @@ __mb_cache_entry_find(struct list_head *l, struct list_head *head,
 217                         }
 218                         finish_wait(&mb_cache_queue, &wait);
 219
 220 -                       if (!__mb_cache_entry_is_hashed(ce)) {
 221 +                       if (!__mb_cache_entry_is_block_hashed(ce)) {
 222                                 __mb_cache_entry_release_unlock(ce);
 223                                 spin_lock(&mb_cache_spinlock);
 224                                 return ERR_PTR(-EAGAIN);
 225 @@ -562,12 +593,16 @@ mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
 226                           unsigned int key)
 227  {
 228         unsigned int bucket = hash_long(key, cache->c_bucket_bits);
 229 -       struct list_head *l;
 230 -       struct mb_cache_entry *ce;
 231 +       struct hlist_bl_node *l;
 232 +       struct mb_cache_entry *ce = NULL;
 233 +       struct hlist_bl_head *index_hash_p;
 234
 235 +       index_hash_p = &cache->c_index_hash[bucket];
 236         spin_lock(&mb_cache_spinlock);
 237 -       l = cache->c_index_hash[bucket].next;
 238 -       ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
 239 +       if (!hlist_bl_empty(index_hash_p)) {
 240 +               l = hlist_bl_first(index_hash_p);
 241 +               ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
 242 +       }
 243         spin_unlock(&mb_cache_spinlock);
 244         return ce;
 245  }
 246 @@ -597,12 +632,16 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev,
 247  {
 248         struct mb_cache *cache = prev->e_cache;
 249         unsigned int bucket = hash_long(key, cache->c_bucket_bits);
 250 -       struct list_head *l;
 251 +       struct hlist_bl_node *l;
 252         struct mb_cache_entry *ce;
 253 +       struct hlist_bl_head *index_hash_p;
 254
 255 +       index_hash_p = &cache->c_index_hash[bucket];
 256 +       mb_assert(prev->e_index_hash_p == index_hash_p);
 257         spin_lock(&mb_cache_spinlock);
 258 +       mb_assert(!hlist_bl_empty(index_hash_p));
 259         l = prev->e_index.o_list.next;
 260 -       ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
 261 +       ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
 262         __mb_cache_entry_release_unlock(prev);
 263         return ce;
 264  }
 265 diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
 266 index 5525d37..6a392e7 100644
 267 --- a/include/linux/mbcache.h
 268 +++ b/include/linux/mbcache.h
 269 @@ -3,19 +3,21 @@
 270
 271    (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
 272  */
 273 -
 274  struct mb_cache_entry {
 275         struct list_head                e_lru_list;
 276         struct mb_cache                 *e_cache;
 277         unsigned short                  e_used;
 278         unsigned short                  e_queued;
 279 +       atomic_t                        e_refcnt;
 280         struct block_device             *e_bdev;
 281         sector_t                        e_block;
 282 -       struct list_head                e_block_list;
 283 +       struct hlist_bl_node            e_block_list;
 284         struct {
 285 -               struct list_head        o_list;
 286 +               struct hlist_bl_node    o_list;
 287                 unsigned int            o_key;
 288         } e_index;
 289 +       struct hlist_bl_head            *e_block_hash_p;
 290 +       struct hlist_bl_head            *e_index_hash_p;
 291  };
 292
 293  struct mb_cache {
 294 @@ -25,8 +27,8 @@ struct mb_cache {
 295         int                             c_max_entries;
 296         int                             c_bucket_bits;
 297         struct kmem_cache               *c_entry_cache;
 298 -       struct list_head                *c_block_hash;
 299 -       struct list_head                *c_index_hash;
 300 +       struct hlist_bl_head            *c_block_hash;
 301 +       struct hlist_bl_head            *c_index_hash;
 302  };
 303
 304  /* Functions on caches */
 305 --
 306 1.7.11.3
 307
 308