This patch changes each mb_cache's both block and index hash chains from
regular linked list to hlist_bl_node, which contains a built-in lock. This is
the first step in decoupling of locks serializing accesses to mb_cache global
data and each mb_cache_entry local data.
Signed-off-by: T. Makphaibulchoke <tmac@xxxxxx>
---
Changed in v5:
- Added e_refcnt member to mb_cache_entry structure to be used in
the decoupling in patch 2/3.
- Removed e_entry_lock from mb_cache_entry structure.
fs/mbcache.c | 117 ++++++++++++++++++++++++++++++++----------------
include/linux/mbcache.h | 12 ++---
2 files changed, 85 insertions(+), 44 deletions(-)
diff --git a/fs/mbcache.c b/fs/mbcache.c
index e519e45..55db0da 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -34,9 +34,9 @@
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/sched.h>
-#include <linux/init.h>
+#include <linux/list_bl.h>
#include <linux/mbcache.h>
-
+#include <linux/init.h>
#ifdef MB_CACHE_DEBUG
# define mb_debug(f...) do { \
@@ -87,21 +87,38 @@ static LIST_HEAD(mb_cache_lru_list);
static DEFINE_SPINLOCK(mb_cache_spinlock);
static inline int
-__mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
+__mb_cache_entry_is_block_hashed(struct mb_cache_entry *ce)
{
- return !list_empty(&ce->e_block_list);
+ return !hlist_bl_unhashed(&ce->e_block_list);
}
-static void
-__mb_cache_entry_unhash(struct mb_cache_entry *ce)
+static inline void
+__mb_cache_entry_unhash_block(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);
- }
+ if (__mb_cache_entry_is_block_hashed(ce))
+ hlist_bl_del_init(&ce->e_block_list);
+}
+
+static inline int
+__mb_cache_entry_is_index_hashed(struct mb_cache_entry *ce)
+{
+ return !hlist_bl_unhashed(&ce->e_index.o_list);
}
+static inline void
+__mb_cache_entry_unhash_index(struct mb_cache_entry *ce)
+{
+ if (__mb_cache_entry_is_index_hashed(ce))
+ hlist_bl_del_init(&ce->e_index.o_list);
+}
+
+static inline void
+__mb_cache_entry_unhash(struct mb_cache_entry *ce)
+{
+ __mb_cache_entry_unhash_index(ce);
+ __mb_cache_entry_unhash_block(ce);
+}
static void
__mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
@@ -125,7 +142,7 @@ __mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
ce->e_used -= MB_CACHE_WRITER;
ce->e_used--;
if (!(ce->e_used || ce->e_queued)) {
- if (!__mb_cache_entry_is_hashed(ce))
+ if (!__mb_cache_entry_is_block_hashed(ce))
goto forget;
mb_assert(list_empty(&ce->e_lru_list));
list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
@@ -221,18 +238,18 @@ 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);
@@ -364,10 +381,13 @@ 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;
}
@@ -393,25 +413,32 @@ 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;
+ mb_assert(ce);
bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
cache->c_bucket_bits);
+ block_hash_p = &cache->c_block_hash[bucket];
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)
+ 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_block_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]);
+ 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];
+ ce->e_index_hash_p = index_hash_p;
+ hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
+ hlist_bl_add_head(&ce->e_block_list, block_hash_p);
error = 0;
out:
spin_unlock(&mb_cache_spinlock);
@@ -463,14 +490,16 @@ 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);
+ block_hash_p = &cache->c_block_hash[bucket];
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);
+ 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);
@@ -489,7 +518,7 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
finish_wait(&mb_cache_queue, &wait);
ce->e_used += 1 + MB_CACHE_WRITER;
- if (!__mb_cache_entry_is_hashed(ce)) {
+ if (!__mb_cache_entry_is_block_hashed(ce)) {
__mb_cache_entry_release_unlock(ce);
return NULL;
}
@@ -506,12 +535,14 @@ cleanup:
#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);
+ mb_assert(ce->e_index_hash_p == head);
if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
DEFINE_WAIT(wait);
@@ -532,7 +563,7 @@ __mb_cache_entry_find(struct list_head *l, struct list_head *head,
}
finish_wait(&mb_cache_queue, &wait);
- if (!__mb_cache_entry_is_hashed(ce)) {
+ if (!__mb_cache_entry_is_block_hashed(ce)) {
__mb_cache_entry_release_unlock(ce);
spin_lock(&mb_cache_spinlock);
return ERR_PTR(-EAGAIN);
@@ -562,12 +593,16 @@ 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;
+ index_hash_p = &cache->c_index_hash[bucket];
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);
+ 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);
+ }
spin_unlock(&mb_cache_spinlock);
return ce;
}
@@ -597,12 +632,16 @@ 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;
+ index_hash_p = &cache->c_index_hash[bucket];
+ mb_assert(prev->e_index_hash_p == index_hash_p);
spin_lock(&mb_cache_spinlock);
+ 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);
+ ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
__mb_cache_entry_release_unlock(prev);
return ce;
}
diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
index 5525d37..6a392e7 100644
--- a/include/linux/mbcache.h
+++ b/include/linux/mbcache.h
@@ -3,19 +3,21 @@
(C) 2001 by Andreas Gruenbacher, <a.gruenbacher@xxxxxxxxxxxx>
*/
-
struct mb_cache_entry {
struct list_head e_lru_list;
struct mb_cache *e_cache;
unsigned short e_used;
unsigned short e_queued;
+ atomic_t e_refcnt;
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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