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 <tmac@xxxxxx>
---
fs/mbcache.c | 419 +++++++++++++++++++++++++++++++++++++-----------
include/linux/mbcache.h | 5 +
2 files changed, 334 insertions(+), 90 deletions(-)
diff --git a/fs/mbcache.c b/fs/mbcache.c
index 8c32ef3..01a0c09 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>
@@ -57,6 +67,8 @@
#define MB_CACHE_WRITER ((unsigned short)~0U >> 1)
+#define MAX_LOCK_RETRY 2048
+
static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue);
MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbacher@xxxxxxxxxxxx>");
@@ -109,11 +121,28 @@ static void
__mb_cache_entry_unhash(struct mb_cache_entry *ce)
{
if (__mb_cache_entry_is_hashed(ce)) {
+ struct mb_cache *cache = ce->e_cache;
+ spinlock_t *key_lock = &cache->c_key_locks[ce->e_key_lock];
+
list_del_init(&ce->e_block_list);
+ spin_lock(key_lock);
list_del(&ce->e_index.o_list);
+ spin_unlock(key_lock);
}
}
+static void
+__mb_cache_entry_unhash_lock(struct mb_cache_entry *ce)
+{
+ struct mb_cache *cache = ce->e_cache;
+ int lock_index = ce->e_bdev_lock;
+
+ spin_lock(&cache->c_bdev_locks[lock_index]);
+ mb_assert(lock_index == ce->e_bdev_lock);
+ __mb_cache_entry_unhash(ce);
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+}
+
static void
__mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
@@ -127,8 +156,9 @@ __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,
+ spinlock_t *hash_lock)
+ __releases(hash_lock)
{
/* Wake up all processes queuing for this cache entry. */
if (ce->e_queued)
@@ -139,13 +169,17 @@ __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);
+ spin_unlock(hash_lock);
+ 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
+ spin_unlock(hash_lock);
return;
forget:
- spin_unlock(&mb_cache_spinlock);
+ spin_unlock(hash_lock);
+ mb_assert(list_empty(&ce->e_lru_list));
__mb_cache_entry_forget(ce, GFP_KERNEL);
}
@@ -164,31 +198,59 @@ 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,
+ while ((nr_to_scan > 0) && (max_loop-- > 0)) {
+ struct mb_cache *cache;
+ struct mb_cache_entry *ce;
+ int nloops = 0;
+ int lock_index;
+
+ 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_move_tail(&ce->e_lru_list, &free_list);
+ list_del_init(&ce->e_lru_list);
+ spin_unlock(&mb_cache_spinlock);
+
+ cache = ce->e_cache;
+ lock_index = ce->e_bdev_lock;
+ spin_lock(&cache->c_bdev_locks[lock_index]);
+ while ((lock_index != ce->e_bdev_lock) &&
+ (nloops++ < MAX_LOCK_RETRY)) {
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ lock_index = ce->e_bdev_lock;
+ spin_lock(&cache->c_bdev_locks[lock_index]);
+ }
+ if (nloops >= MAX_LOCK_RETRY) {
+ mb_assert(FALSE);
+ continue;
+ }
+ if (ce->e_used || ce->e_queued) {
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ continue;
+ }
+
__mb_cache_entry_unhash(ce);
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ __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;
}
@@ -209,6 +271,7 @@ mb_cache_create(const char *name, int bucket_bits)
{
int n, bucket_count = 1 << bucket_bits;
struct mb_cache *cache = NULL;
+ int num_locks;
cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL);
if (!cache)
@@ -234,6 +297,28 @@ mb_cache_create(const char *name, int bucket_bits)
if (!cache->c_entry_cache)
goto fail2;
+ num_locks = 1 << (bucket_bits - 4);
+ cache->c_bdev_locks = kmalloc(num_locks * sizeof(spinlock_t),
+ GFP_KERNEL);
+ if (!cache->c_bdev_locks) {
+ kfree(cache->c_entry_cache);
+ goto fail2;
+ }
+
+ cache->c_key_locks = kmalloc(num_locks * sizeof(spinlock_t),
+ GFP_KERNEL);
+ if (!cache->c_key_locks) {
+ kfree(cache->c_bdev_locks);
+ kfree(cache->c_entry_cache);
+ goto fail2;
+ }
+
+ cache->c_lock_mask = num_locks - 1;
+ for (n = 0; n < num_locks; n++)
+ spin_lock_init(&cache->c_bdev_locks[n]);
+ for (n = 0; n < num_locks; n++)
+ spin_lock_init(&cache->c_key_locks[n]);
+
/*
* Set an upper limit on the number of cache entries so that the hash
* chains won't grow too long.
@@ -276,13 +361,36 @@ 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);
+ int lock_index;
+ int nloops = 0;
+ struct mb_cache_entry *ce =
+ list_entry(l, struct mb_cache_entry, e_lru_list);
+ struct mb_cache *cache = ce->e_cache;
+
+ lock_index = ce->e_bdev_lock;
+ spin_lock(&cache->c_bdev_locks[lock_index]);
+ while ((lock_index != ce->e_bdev_lock) &&
+ (nloops++ < MAX_LOCK_RETRY)) {
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ lock_index = ce->e_bdev_lock;
+ spin_lock(&cache->c_bdev_locks[lock_index]);
+ }
+ if (nloops > MAX_LOCK_RETRY) {
+ mb_assert(FALSE);
+ continue;
+ }
+ if (ce->e_used || ce->e_queued) {
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ continue;
+ }
+
+ __mb_cache_entry_unhash(ce);
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ __mb_cache_entry_forget(ce, GFP_KERNEL);
}
}
@@ -306,15 +414,16 @@ 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_cache_entry_unhash_lock(ce);
+ __mb_cache_entry_forget(ce, GFP_KERNEL);
}
if (atomic_read(&cache->c_entry_count) > 0) {
@@ -325,6 +434,8 @@ mb_cache_destroy(struct mb_cache *cache)
kmem_cache_destroy(cache->c_entry_cache);
+ kfree(cache->c_key_locks);
+ kfree(cache->c_bdev_locks);
kfree(cache->c_index_hash);
kfree(cache->c_block_hash);
kfree(cache);
@@ -344,26 +455,60 @@ 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, *ltmp;
+
+retry:
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) {
+ int lock_index = ce->e_bdev_lock;
+ spinlock_t *bdev_lock = &cache->
+ c_bdev_locks[lock_index];
+ int nloops = 0;
+
+ list_del_init(&ce->e_lru_list);
+ spin_unlock(&mb_cache_spinlock);
+ spin_lock(bdev_lock);
+ while ((lock_index != ce->e_bdev_lock) &&
+ (nloops++ < MAX_LOCK_RETRY)) {
+ spin_unlock(bdev_lock);
+ lock_index = ce->e_bdev_lock;
+ bdev_lock = &cache->
+ c_bdev_locks[lock_index];
+ spin_lock(bdev_lock);
+ }
+ if (nloops > MAX_LOCK_RETRY) {
+ mb_assert(FALSE);
+ continue;
+ }
+ if (ce->e_used || ce->e_queued) {
+ pr_warn("%s: ce %p is still being referenced..\n",
+ __func__, ce);
+ spin_unlock(bdev_lock);
+ goto retry;
+ }
+ __mb_cache_entry_unhash(ce);
+ ce->e_used = 1 + MB_CACHE_WRITER;
+ spin_unlock(bdev_lock);
+ return ce;
+ }
}
spin_unlock(&mb_cache_spinlock);
}
- if (!ce) {
- ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
- if (!ce)
- return NULL;
- atomic_inc(&cache->c_entry_count);
- INIT_LIST_HEAD(&ce->e_lru_list);
- INIT_LIST_HEAD(&ce->e_block_list);
- ce->e_cache = cache;
- ce->e_queued = 0;
- }
+
+ ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
+ if (!ce)
+ return NULL;
+ atomic_inc(&cache->c_entry_count);
+ INIT_LIST_HEAD(&ce->e_lru_list);
+ INIT_LIST_HEAD(&ce->e_block_list);
+ INIT_LIST_HEAD(&ce->e_index.o_list);
+ ce->e_cache = cache;
+ ce->e_queued = 0;
ce->e_used = 1 + MB_CACHE_WRITER;
+ ce->e_bdev_lock = 0;
+ ce->e_key_lock = 0;
return ce;
}
@@ -390,27 +535,42 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
unsigned int bucket;
struct list_head *l;
int error = -EBUSY;
+ int lock_index;
+ spinlock_t *key_lock;
+ int key_index;
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
cache->c_bucket_bits);
- spin_lock(&mb_cache_spinlock);
+ lock_index = bucket & cache->c_lock_mask;
+ if ((ce->e_used != 1 + MB_CACHE_WRITER) || ce->e_queued)
+ pr_warn("%s: attempt to insert an in-used ce %p.\n",
+ __func__, ce);
+ __mb_cache_entry_unhash_lock(ce);
+
+ spin_lock(&cache->c_bdev_locks[lock_index]);
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)
- goto out;
+ if (ce->e_bdev == bdev && ce->e_block == block) {
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ return error;
+ }
}
- __mb_cache_entry_unhash(ce);
+
+ ce->e_bdev_lock = lock_index;
ce->e_bdev = bdev;
ce->e_block = block;
list_add(&ce->e_block_list, &cache->c_block_hash[bucket]);
ce->e_index.o_key = key;
bucket = hash_long(key, cache->c_bucket_bits);
+ key_index = bucket & cache->c_lock_mask;
+ key_lock = &cache->c_key_locks[key_index];
+ spin_lock(key_lock);
+ ce->e_key_lock = key_index;
list_add(&ce->e_index.o_list, &cache->c_index_hash[bucket]);
- error = 0;
-out:
- spin_unlock(&mb_cache_spinlock);
- return error;
+ spin_unlock(key_lock);
+ spin_unlock(&cache->c_bdev_locks[lock_index]);
+ return 0;
}
@@ -424,8 +584,14 @@ out:
void
mb_cache_entry_release(struct mb_cache_entry *ce)
{
- spin_lock(&mb_cache_spinlock);
- __mb_cache_entry_release_unlock(ce);
+ struct mb_cache *cache = ce->e_cache;
+ spinlock_t *hash_lock;
+ int lock_index = ce->e_bdev_lock;
+
+ hash_lock = &cache->c_bdev_locks[lock_index];
+ spin_lock(hash_lock);
+ mb_assert(lock_index == ce->e_bdev_lock);
+ __mb_cache_entry_release_unlock(ce, hash_lock);
}
@@ -438,10 +604,21 @@ mb_cache_entry_release(struct mb_cache_entry *ce)
void
mb_cache_entry_free(struct mb_cache_entry *ce)
{
- spin_lock(&mb_cache_spinlock);
+ struct mb_cache *cache = ce->e_cache;
+ spinlock_t *hash_lock;
+ int lock_index = ce->e_bdev_lock;
+
+ if (!list_empty(&ce->e_lru_list)) {
+ pr_warn("%s: attempt to free ce %p still in-used.\n",
+ __func__, ce);
+ return;
+ }
mb_assert(list_empty(&ce->e_lru_list));
+ hash_lock = &cache->c_bdev_locks[lock_index];
+ spin_lock(hash_lock);
+ mb_assert(lock_index == ce->e_bdev_lock);
__mb_cache_entry_unhash(ce);
- __mb_cache_entry_release_unlock(ce);
+ __mb_cache_entry_release_unlock(ce, hash_lock);
}
@@ -460,32 +637,43 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
unsigned int bucket;
struct list_head *l;
struct mb_cache_entry *ce;
+ spinlock_t *hash_lock;
+ int hash_index;
+ int lock_index;
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
cache->c_bucket_bits);
- spin_lock(&mb_cache_spinlock);
+ hash_index = bucket & cache->c_lock_mask;
+ hash_lock = &cache->c_bdev_locks[hash_index];
+ spin_lock(hash_lock);
list_for_each(l, &cache->c_block_hash[bucket]) {
ce = list_entry(l, struct mb_cache_entry, e_block_list);
+ mb_assert(hash_index == ce->e_bdev_lock);
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);
+ lock_index = ce->e_bdev_lock;
+ spin_unlock(hash_lock);
schedule();
- spin_lock(&mb_cache_spinlock);
- ce->e_queued--;
+ spin_lock(hash_lock);
+ mb_assert(lock_index == ce->e_bdev_lock);
+ 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_assert(hash_index == ce->e_bdev_lock);
+ __mb_cache_entry_release_unlock(ce, hash_lock);
return NULL;
}
goto cleanup;
@@ -494,47 +682,76 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
ce = NULL;
cleanup:
- spin_unlock(&mb_cache_spinlock);
+ spin_unlock(hash_lock);
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,
- struct block_device *bdev, unsigned int key)
+__mb_cache_entry_find_unlock(struct list_head *l, struct list_head *head,
+ struct block_device *bdev, unsigned int key, int lock_index)
{
+ struct mb_cache_entry *ce;
+ struct mb_cache *cache;
+ spinlock_t *key_lock;
+ int found = 0;
+
+ mb_assert(l != head);
+ if (l == head)
+ return NULL;
+
+ ce = list_entry(l, struct mb_cache_entry, e_index.o_list);
+ cache = ce->e_cache;
+ mb_assert((lock_index >= 0) && (lock_index <= cache->c_lock_mask));
+ key_lock = &cache->c_key_locks[lock_index];
+
while (l != head) {
- struct mb_cache_entry *ce =
- list_entry(l, struct mb_cache_entry, e_index.o_list);
+ ce = list_entry(l, struct mb_cache_entry, e_index.o_list);
+ mb_assert(lock_index == ce->e_key_lock);
if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
- DEFINE_WAIT(wait);
+ found = 1;
+ break;
+ }
+ l = l->next;
+ }
+ spin_unlock(key_lock);
- if (!list_empty(&ce->e_lru_list))
- list_del_init(&ce->e_lru_list);
+ if (found) {
+ int hash_index;
+ spinlock_t *hash_lock;
+ DEFINE_WAIT(wait);
- /* Incrementing before holding the lock gives readers
- priority over writers. */
- ce->e_used++;
- while (ce->e_used >= MB_CACHE_WRITER) {
- ce->e_queued++;
- prepare_to_wait(&mb_cache_queue, &wait,
- TASK_UNINTERRUPTIBLE);
- spin_unlock(&mb_cache_spinlock);
- schedule();
- spin_lock(&mb_cache_spinlock);
- ce->e_queued--;
- }
- finish_wait(&mb_cache_queue, &wait);
+ hash_index = ce->e_bdev_lock;
+ hash_lock = &cache->c_bdev_locks[hash_index];
- if (!__mb_cache_entry_is_hashed(ce)) {
- __mb_cache_entry_release_unlock(ce);
- spin_lock(&mb_cache_spinlock);
- return ERR_PTR(-EAGAIN);
- }
- return ce;
+ spin_lock(&mb_cache_spinlock);
+ if (!list_empty(&ce->e_lru_list))
+ list_del_init(&ce->e_lru_list);
+ spin_unlock(&mb_cache_spinlock);
+
+ spin_lock(hash_lock);
+ /* Incrementing before holding the lock gives readers
+ priority over writers. */
+ ce->e_used++;
+ while (ce->e_used >= MB_CACHE_WRITER) {
+ ce->e_queued++;
+ prepare_to_wait(&mb_cache_queue, &wait,
+ TASK_UNINTERRUPTIBLE);
+ spin_unlock(hash_lock);
+ schedule();
+ spin_lock(hash_lock);
+ mb_assert(hash_index == ce->e_bdev_lock);
+ ce->e_queued++;
}
- l = l->next;
+ finish_wait(&mb_cache_queue, &wait);
+
+ if (!__mb_cache_entry_is_hashed(ce)) {
+ __mb_cache_entry_release_unlock(ce, hash_lock);
+ return ERR_PTR(-EAGAIN);
+ }
+ spin_unlock(hash_lock);
+ return ce;
}
return NULL;
}
@@ -559,11 +776,18 @@ mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
unsigned int bucket = hash_long(key, cache->c_bucket_bits);
struct list_head *l;
struct mb_cache_entry *ce;
+ int lock_index = bucket & cache->c_lock_mask;
+ spinlock_t *key_lock = &cache->c_key_locks[lock_index];
- spin_lock(&mb_cache_spinlock);
+ spin_lock(key_lock);
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);
+ if (l == &cache->c_index_hash[bucket]) {
+ spin_unlock(key_lock);
+ return NULL;
+ }
+ ce = __mb_cache_entry_find_unlock(l, &cache->c_index_hash[bucket],
+ bdev, key, lock_index);
+ mb_assert(!ce || (lock_index == ce->e_key_lock));
return ce;
}
@@ -593,12 +817,27 @@ 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 mb_cache_entry *ce;
+ struct mb_cache_entry *ce = NULL;
+ int lock_index = bucket & cache->c_lock_mask;
+ spinlock_t *lock;
- spin_lock(&mb_cache_spinlock);
+ lock = &cache->c_key_locks[lock_index];
+ spin_lock(lock);
+ mb_assert(lock_index == prev->e_key_lock);
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);
+ if (l == &cache->c_index_hash[bucket])
+ spin_unlock(lock);
+ else {
+ ce = __mb_cache_entry_find_unlock(l, &cache->
+ c_index_hash[bucket], bdev, key, lock_index);
+ mb_assert(!ce || (lock_index == ce->e_key_lock));
+ }
+
+ lock_index = prev->e_bdev_lock;
+ lock = &cache->c_bdev_locks[lock_index];
+ spin_lock(lock);
+ mb_assert(lock_index == prev->e_bdev_lock);
+ __mb_cache_entry_release_unlock(prev, lock);
return ce;
}
diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
index 5525d37..68d8409 100644
--- a/include/linux/mbcache.h
+++ b/include/linux/mbcache.h
@@ -9,6 +9,8 @@ struct mb_cache_entry {
struct mb_cache *e_cache;
unsigned short e_used;
unsigned short e_queued;
+ unsigned int e_bdev_lock;
+ unsigned int e_key_lock;
struct block_device *e_bdev;
sector_t e_block;
struct list_head e_block_list;
@@ -27,6 +29,9 @@ struct mb_cache {
struct kmem_cache *c_entry_cache;
struct list_head *c_block_hash;
struct list_head *c_index_hash;
+ spinlock_t *c_bdev_locks;
+ spinlock_t *c_key_locks;
+ unsigned int c_lock_mask;
};
/* Functions on caches */
--
1.7.11.3
--
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