The patch increases the parallelism of mb_cache_entry utilization by
introducing new spinlocks to the mb_cache structure to protect the mb_cache
local block and index hash chains, while the global mb_cache_lru_list and
mb_cache_list continue to be protected by the global mb_cache_spinlock.

Signed-off-by: T. Makphaibulchoke <t...@hp.com>
---
Changed in v2:
        - As per Linus Torvalds' suggestion, instead of allocating spinlock
          arrays to protect the hash chains, use hlist_bl_head, which already
          contains builtin lock.

 fs/mbcache.c            | 293 +++++++++++++++++++++++++++++++++++-------------
 include/linux/mbcache.h |  10 +-
 2 files changed, 221 insertions(+), 82 deletions(-)

diff --git a/fs/mbcache.c b/fs/mbcache.c
index 8c32ef3..cd4446e 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -26,6 +26,16 @@
  * back on the lru list.
  */
 
+/* Locking protocol:
+ *
+ * The nth hash chain of both the c_block_hash and c_index_hash are
+ * protected by the mth entry of the c_bdev_locks and c_key_locks respectively,
+ * where m is equal to n & c_lock_mask.
+ *
+ * While holding a c_bdev_locks, a thread can acquire either a c_key_locks
+ * or mb_cache_spinlock.
+ */
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 
@@ -35,9 +45,9 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/init.h>
+#include <linux/list_bl.h>
 #include <linux/mbcache.h>
 
-
 #ifdef MB_CACHE_DEBUG
 # define mb_debug(f...) do { \
                printk(KERN_DEBUG f); \
@@ -57,6 +67,40 @@
 
 #define MB_CACHE_WRITER ((unsigned short)~0U >> 1)
 
+#define        MB_LOCK_HASH_CHAIN(hash_head)   hlist_bl_lock(hash_head)
+#define        MB_UNLOCK_HASH_CHAIN(hash_head) hlist_bl_unlock(hash_head)
+#ifdef MB_CACHE_DEBUG
+#define        MB_LOCK_BLOCK_HASH(ce) do {                                     
\
+               struct hlist_bl_head *block_hash_p = ce->e_block_hash_p;\
+               MB_LOCK_HASH_CHAIN(block_hash_p);                       \
+               mb_assert(ce->e_block_hash_p == block_hash_p);          \
+       } while (0)
+#else
+#define        MB_LOCK_BLOCK_HASH(ce)  MB_LOCK_HASH_CHAIN(ce->e_block_hash_p)
+#endif
+#define        MB_UNLOCK_BLOCK_HASH(ce)        
MB_UNLOCK_HASH_CHAIN(ce->e_block_hash_p)
+#define        MB_LOCK_INDEX_HASH(ce)          
MB_LOCK_HASH_CHAIN(ce->e_index_hash_p)
+#define        MB_UNLOCK_INDEX_HASH(ce)        
MB_UNLOCK_HASH_CHAIN(ce->e_index_hash_p)
+
+#define        MAX_LOCK_RETRY  1024
+
+static inline int __mb_cache_lock_entry_block_hash(struct mb_cache_entry *ce)
+{
+       int nretry = 0;
+       struct hlist_bl_head *block_hash_p = ce->e_block_hash_p;
+
+       do {
+               MB_LOCK_HASH_CHAIN(block_hash_p);
+               if (ce->e_block_hash_p == block_hash_p)
+                       return 0;
+               MB_UNLOCK_HASH_CHAIN(block_hash_p);
+               block_hash_p = ce->e_block_hash_p;
+       } while (++nretry < MAX_LOCK_RETRY);
+       return -1;
+}
+
+#define        MB_LOCK_ENTRY_BLOCK_HASH(ce)    
__mb_cache_lock_entry_block_hash(ce)
+
 static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue);
                
 MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbac...@computer.org>");
@@ -101,7 +145,7 @@ static struct shrinker mb_cache_shrinker = {
 static inline int
 __mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
 {
-       return !list_empty(&ce->e_block_list);
+       return !hlist_bl_unhashed(&ce->e_block_list);
 }
 
 
@@ -109,11 +153,26 @@ static void
 __mb_cache_entry_unhash(struct mb_cache_entry *ce)
 {
        if (__mb_cache_entry_is_hashed(ce)) {
-               list_del_init(&ce->e_block_list);
-               list_del(&ce->e_index.o_list);
+               hlist_bl_del_init(&ce->e_block_list);
+               MB_LOCK_INDEX_HASH(ce);
+               hlist_bl_del(&ce->e_index.o_list);
+               MB_UNLOCK_INDEX_HASH(ce);
        }
 }
 
+#ifdef MAK_SRC
+static void
+__mb_cache_entry_unhash_nolock(struct mb_cache_entry *ce)
+{
+       mb_assert(!__mb_cache_entry_is_hashed(ce));
+       mb_assert(!ce->e_block_hash_p);
+       mb_assert(!ce->e_index_hash_p);
+
+       hlist_bl_del_init(&ce->e_block_list);
+       hlist_bl_del(&ce->e_index.o_list);
+}
+#endif /* MAK_SRC */
+
 
 static void
 __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
@@ -127,9 +186,10 @@ __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t 
gfp_mask)
 
 
 static void
-__mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
-       __releases(mb_cache_spinlock)
+__mb_cache_entry_release_unlock(struct mb_cache_entry *ce,
+       struct hlist_bl_head *hash_p)
 {
+       mb_assert(hash_p);
        /* Wake up all processes queuing for this cache entry. */
        if (ce->e_queued)
                wake_up_all(&mb_cache_queue);
@@ -139,13 +199,17 @@ __mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
        if (!(ce->e_used || ce->e_queued)) {
                if (!__mb_cache_entry_is_hashed(ce))
                        goto forget;
-               mb_assert(list_empty(&ce->e_lru_list));
-               list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
-       }
-       spin_unlock(&mb_cache_spinlock);
+               MB_UNLOCK_HASH_CHAIN(hash_p);
+               spin_lock(&mb_cache_spinlock);
+               if (list_empty(&ce->e_lru_list))
+                       list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
+               spin_unlock(&mb_cache_spinlock);
+       } else
+               MB_UNLOCK_HASH_CHAIN(hash_p);
        return;
 forget:
-       spin_unlock(&mb_cache_spinlock);
+       MB_UNLOCK_HASH_CHAIN(hash_p);
+       mb_assert(list_empty(&ce->e_lru_list));
        __mb_cache_entry_forget(ce, GFP_KERNEL);
 }
 
@@ -164,31 +228,45 @@ forget:
 static int
 mb_cache_shrink_fn(struct shrinker *shrink, struct shrink_control *sc)
 {
-       LIST_HEAD(free_list);
        struct mb_cache *cache;
-       struct mb_cache_entry *entry, *tmp;
        int count = 0;
        int nr_to_scan = sc->nr_to_scan;
        gfp_t gfp_mask = sc->gfp_mask;
+       int max_loop = nr_to_scan << 1;
 
        mb_debug("trying to free %d entries", nr_to_scan);
-       spin_lock(&mb_cache_spinlock);
-       while (nr_to_scan-- && !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_move_tail(&ce->e_lru_list, &free_list);
+       while ((nr_to_scan-- > 0) && (max_loop-- > 0)) {
+               struct mb_cache_entry *ce;
+
+               spin_lock(&mb_cache_spinlock);
+               if (list_empty(&mb_cache_lru_list)) {
+                       spin_unlock(&mb_cache_spinlock);
+                       break;
+               }
+               ce = list_entry(mb_cache_lru_list.next,
+                       struct mb_cache_entry, e_lru_list);
+               list_del_init(&ce->e_lru_list);
+               spin_unlock(&mb_cache_spinlock);
+
+               if (MB_LOCK_ENTRY_BLOCK_HASH(ce)) {
+                       spin_lock(&mb_cache_spinlock);
+                       list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
+                       spin_unlock(&mb_cache_spinlock);
+                       continue;
+               }
+               mb_assert(!(ce->e_used || ce->e_queued));
                __mb_cache_entry_unhash(ce);
+               MB_UNLOCK_BLOCK_HASH(ce);
+               __mb_cache_entry_forget(ce, gfp_mask);
+               nr_to_scan--;
        }
+       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);
-       list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
-               __mb_cache_entry_forget(entry, gfp_mask);
-       }
        return (count / 100) * sysctl_vfs_cache_pressure;
 }
 
@@ -216,18 +294,18 @@ mb_cache_create(const char *name, int bucket_bits)
        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 list_head),
-                                     GFP_KERNEL);
+       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_LIST_HEAD(&cache->c_block_hash[n]);
-       cache->c_index_hash = kmalloc(bucket_count * sizeof(struct list_head),
-                                     GFP_KERNEL);
+               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_LIST_HEAD(&cache->c_index_hash[n]);
+               INIT_HLIST_BL_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);
@@ -276,13 +354,22 @@ mb_cache_shrink(struct block_device *bdev)
                        list_entry(l, struct mb_cache_entry, e_lru_list);
                if (ce->e_bdev == bdev) {
                        list_move_tail(&ce->e_lru_list, &free_list);
-                       __mb_cache_entry_unhash(ce);
                }
        }
        spin_unlock(&mb_cache_spinlock);
        list_for_each_safe(l, ltmp, &free_list) {
-               __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
-                                                  e_lru_list), GFP_KERNEL);
+               struct mb_cache_entry *ce =
+                       list_entry(l, struct mb_cache_entry, e_lru_list);
+               if (MB_LOCK_ENTRY_BLOCK_HASH(ce)) {
+                       spin_lock(&mb_cache_spinlock);
+                       list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
+                       spin_unlock(&mb_cache_spinlock);
+                       continue;
+               }
+               mb_assert(!ce->e_used && !ce->e_queued);
+               __mb_cache_entry_unhash(ce);
+               MB_UNLOCK_BLOCK_HASH(ce);
+               __mb_cache_entry_forget(ce, GFP_KERNEL);
        }
 }
 
@@ -306,15 +393,18 @@ mb_cache_destroy(struct mb_cache *cache)
                        list_entry(l, struct mb_cache_entry, e_lru_list);
                if (ce->e_cache == cache) {
                        list_move_tail(&ce->e_lru_list, &free_list);
-                       __mb_cache_entry_unhash(ce);
                }
        }
        list_del(&cache->c_cache_list);
        spin_unlock(&mb_cache_spinlock);
 
        list_for_each_safe(l, ltmp, &free_list) {
-               __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
-                                                  e_lru_list), GFP_KERNEL);
+               struct mb_cache_entry *ce =
+                       list_entry(l, struct mb_cache_entry, e_lru_list);
+               MB_LOCK_BLOCK_HASH(ce);
+               __mb_cache_entry_unhash(ce);
+               MB_UNLOCK_BLOCK_HASH(ce);
+               __mb_cache_entry_forget(ce, GFP_KERNEL);
        }
 
        if (atomic_read(&cache->c_entry_count) > 0) {
@@ -344,12 +434,26 @@ mb_cache_entry_alloc(struct mb_cache *cache, gfp_t 
gfp_flags)
        struct mb_cache_entry *ce = NULL;
 
        if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) {
+               struct list_head *l;
+               struct list_head *ltmp;
+
                spin_lock(&mb_cache_spinlock);
-               if (!list_empty(&mb_cache_lru_list)) {
-                       ce = list_entry(mb_cache_lru_list.next,
-                                       struct mb_cache_entry, e_lru_list);
-                       list_del_init(&ce->e_lru_list);
-                       __mb_cache_entry_unhash(ce);
+               list_for_each_safe(l, ltmp, &mb_cache_lru_list) {
+                       ce = list_entry(l, struct mb_cache_entry, e_lru_list);
+                       if (ce->e_cache == cache) {
+                               list_del_init(&ce->e_lru_list);
+                               spin_unlock(&mb_cache_spinlock);
+                               if (MB_LOCK_ENTRY_BLOCK_HASH(ce)) {
+                                       spin_lock(&mb_cache_spinlock);
+                                       list_add_tail(&ce->e_lru_list,
+                                               &mb_cache_lru_list);
+                                       continue;
+                               }
+                               mb_assert(!ce->e_used && !ce->e_queued);
+                               __mb_cache_entry_unhash(ce);
+                               MB_UNLOCK_BLOCK_HASH(ce);
+                               break;
+                       }
                }
                spin_unlock(&mb_cache_spinlock);
        }
@@ -359,9 +463,12 @@ mb_cache_entry_alloc(struct mb_cache *cache, gfp_t 
gfp_flags)
                        return NULL;
                atomic_inc(&cache->c_entry_count);
                INIT_LIST_HEAD(&ce->e_lru_list);
-               INIT_LIST_HEAD(&ce->e_block_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;
+               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;
@@ -388,28 +495,36 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct 
block_device *bdev,
 {
        struct mb_cache *cache = ce->e_cache;
        unsigned int bucket;
-       struct list_head *l;
+       struct hlist_bl_node *l;
        int error = -EBUSY;
+       struct hlist_bl_head *block_hash_p;
+       struct hlist_bl_head *index_hash_p;
+       struct mb_cache_entry *lce;
 
        bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), 
                           cache->c_bucket_bits);
-       spin_lock(&mb_cache_spinlock);
-       list_for_each_prev(l, &cache->c_block_hash[bucket]) {
-               struct mb_cache_entry *ce =
-                       list_entry(l, struct mb_cache_entry, e_block_list);
-               if (ce->e_bdev == bdev && ce->e_block == block)
+       block_hash_p = &cache->c_block_hash[bucket];
+       MB_LOCK_HASH_CHAIN(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)
                        goto out;
        }
+       mb_assert(!__mb_cache_entry_is_hashed(ce));
        __mb_cache_entry_unhash(ce);
        ce->e_bdev = bdev;
        ce->e_block = block;
-       list_add(&ce->e_block_list, &cache->c_block_hash[bucket]);
+       hlist_bl_add_head(&ce->e_block_list, block_hash_p);
+       ce->e_block_hash_p = block_hash_p;
        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]);
+       index_hash_p = &cache->c_index_hash[bucket];
+       MB_LOCK_HASH_CHAIN(index_hash_p);
+       hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
+       ce->e_index_hash_p = index_hash_p;
+       MB_UNLOCK_HASH_CHAIN(index_hash_p);
        error = 0;
 out:
-       spin_unlock(&mb_cache_spinlock);
+       MB_UNLOCK_HASH_CHAIN(block_hash_p);
        return error;
 }
 
@@ -424,8 +539,8 @@ out:
 void
 mb_cache_entry_release(struct mb_cache_entry *ce)
 {
-       spin_lock(&mb_cache_spinlock);
-       __mb_cache_entry_release_unlock(ce);
+       MB_LOCK_BLOCK_HASH(ce);
+       __mb_cache_entry_release_unlock(ce, ce->e_block_hash_p);
 }
 
 
@@ -438,10 +553,12 @@ mb_cache_entry_release(struct mb_cache_entry *ce)
 void
 mb_cache_entry_free(struct mb_cache_entry *ce)
 {
-       spin_lock(&mb_cache_spinlock);
+       mb_assert(ce);
+       mb_assert(ce->e_block_hash_p);
+       MB_LOCK_BLOCK_HASH(ce);
        mb_assert(list_empty(&ce->e_lru_list));
        __mb_cache_entry_unhash(ce);
-       __mb_cache_entry_release_unlock(ce);
+       __mb_cache_entry_release_unlock(ce, ce->e_block_hash_p);
 }
 
 
@@ -458,34 +575,39 @@ mb_cache_entry_get(struct mb_cache *cache, struct 
block_device *bdev,
                   sector_t block)
 {
        unsigned int bucket;
-       struct list_head *l;
+       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);
-       spin_lock(&mb_cache_spinlock);
-       list_for_each(l, &cache->c_block_hash[bucket]) {
-               ce = list_entry(l, struct mb_cache_entry, e_block_list);
+       block_hash_p = &cache->c_block_hash[bucket];
+       MB_LOCK_HASH_CHAIN(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) {
                        DEFINE_WAIT(wait);
 
+                       spin_lock(&mb_cache_spinlock);
                        if (!list_empty(&ce->e_lru_list))
                                list_del_init(&ce->e_lru_list);
+                       spin_unlock(&mb_cache_spinlock);
 
                        while (ce->e_used > 0) {
                                ce->e_queued++;
                                prepare_to_wait(&mb_cache_queue, &wait,
                                                TASK_UNINTERRUPTIBLE);
-                               spin_unlock(&mb_cache_spinlock);
+                               MB_UNLOCK_BLOCK_HASH(ce);
                                schedule();
-                               spin_lock(&mb_cache_spinlock);
+                               MB_LOCK_BLOCK_HASH(ce);
                                ce->e_queued--;
                        }
                        finish_wait(&mb_cache_queue, &wait);
                        ce->e_used += 1 + MB_CACHE_WRITER;
 
                        if (!__mb_cache_entry_is_hashed(ce)) {
-                               __mb_cache_entry_release_unlock(ce);
+                               __mb_cache_entry_release_unlock(ce,
+                                       block_hash_p);
                                return NULL;
                        }
                        goto cleanup;
@@ -494,25 +616,30 @@ mb_cache_entry_get(struct mb_cache *cache, struct 
block_device *bdev,
        ce = NULL;
 
 cleanup:
-       spin_unlock(&mb_cache_spinlock);
+       MB_UNLOCK_HASH_CHAIN(block_hash_p);
        return ce;
 }
 
 #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
 
 static struct mb_cache_entry *
-__mb_cache_entry_find(struct list_head *l, struct list_head *head,
+__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head,
                      struct block_device *bdev, unsigned int key)
 {
-       while (l != head) {
+       while (l != NULL) {
                struct mb_cache_entry *ce =
-                       list_entry(l, struct mb_cache_entry, e_index.o_list);
+                       hlist_bl_entry(l, struct mb_cache_entry,
+                               e_index.o_list);
                if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
                        DEFINE_WAIT(wait);
 
+                       MB_UNLOCK_HASH_CHAIN(head);
+                       spin_lock(&mb_cache_spinlock);
                        if (!list_empty(&ce->e_lru_list))
                                list_del_init(&ce->e_lru_list);
+                       spin_unlock(&mb_cache_spinlock);
 
+                       MB_LOCK_HASH_CHAIN(head);
                        /* Incrementing before holding the lock gives readers
                           priority over writers. */
                        ce->e_used++;
@@ -520,18 +647,20 @@ __mb_cache_entry_find(struct list_head *l, struct 
list_head *head,
                                ce->e_queued++;
                                prepare_to_wait(&mb_cache_queue, &wait,
                                                TASK_UNINTERRUPTIBLE);
-                               spin_unlock(&mb_cache_spinlock);
+                               MB_UNLOCK_HASH_CHAIN(head);
                                schedule();
-                               spin_lock(&mb_cache_spinlock);
+                               MB_LOCK_HASH_CHAIN(head);
+                               mb_assert(ce->e_index_hash_p == head);
                                ce->e_queued--;
                        }
                        finish_wait(&mb_cache_queue, &wait);
 
                        if (!__mb_cache_entry_is_hashed(ce)) {
-                               __mb_cache_entry_release_unlock(ce);
-                               spin_lock(&mb_cache_spinlock);
+                               __mb_cache_entry_release_unlock(ce, head);
+                               MB_LOCK_HASH_CHAIN(head);
                                return ERR_PTR(-EAGAIN);
                        }
+                       mb_assert(ce->e_index_hash_p == head);
                        return ce;
                }
                l = l->next;
@@ -557,13 +686,17 @@ 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;
+       struct hlist_bl_node *l;
+       struct mb_cache_entry *ce = NULL;
+       struct hlist_bl_head *index_hash_p;
 
-       spin_lock(&mb_cache_spinlock);
-       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);
+       index_hash_p = &cache->c_index_hash[bucket];
+       MB_LOCK_HASH_CHAIN(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);
+       }
+       MB_UNLOCK_HASH_CHAIN(index_hash_p);
        return ce;
 }
 
@@ -592,13 +725,17 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev,
 {
        struct mb_cache *cache = prev->e_cache;
        unsigned int bucket = hash_long(key, cache->c_bucket_bits);
-       struct list_head *l;
+       struct hlist_bl_node *l;
        struct mb_cache_entry *ce;
+       struct hlist_bl_head *index_hash_p;
 
-       spin_lock(&mb_cache_spinlock);
+       index_hash_p = &cache->c_index_hash[bucket];
+       mb_assert(prev->e_index_hash_p == index_hash_p);
+       MB_LOCK_HASH_CHAIN(index_hash_p);
+       mb_assert(!hlist_bl_empty(index_hash_p));
        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);
+       ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
+       MB_UNLOCK_HASH_CHAIN(index_hash_p);
        return ce;
 }
 
diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
index 5525d37..89826c0 100644
--- a/include/linux/mbcache.h
+++ b/include/linux/mbcache.h
@@ -11,11 +11,13 @@ struct mb_cache_entry {
        unsigned short                  e_queued;
        struct block_device             *e_bdev;
        sector_t                        e_block;
-       struct list_head                e_block_list;
+       struct hlist_bl_node            e_block_list;
        struct {
-               struct list_head        o_list;
+               struct hlist_bl_node    o_list;
                unsigned int            o_key;
        } e_index;
+       struct hlist_bl_head            *e_block_hash_p;
+       struct hlist_bl_head            *e_index_hash_p;
 };
 
 struct mb_cache {
@@ -25,8 +27,8 @@ struct mb_cache {
        int                             c_max_entries;
        int                             c_bucket_bits;
        struct kmem_cache               *c_entry_cache;
-       struct list_head                *c_block_hash;
-       struct list_head                *c_index_hash;
+       struct hlist_bl_head            *c_block_hash;
+       struct hlist_bl_head            *c_index_hash;
 };
 
 /* Functions on caches */
-- 
1.7.11.3

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