fs/mbcache.c: change block and index hash chain to hlist_bl_node

This patch changes each mb_cache's both block and index hash chains to
use a 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@hp.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/mbcache.c b/fs/mbcache.c
index e519e45bf6735e7f59dc7fef969451791e5e1cef..55db0daaca74c2f8ee66ca04f7e5900b0594ddc1 100644 (file)
--- 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 5525d370701db049e176456292cdb725366d59f7..6a392e7a723a46d4c6f00715e81b21cbcaac1007 100644 (file)
--- a/include/linux/mbcache.h
+++ b/include/linux/mbcache.h
@@ -3,19 +3,21 @@
 
   (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
 */
-
 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 */