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Commit 3e037e52 authored by T Makphaibulchoke's avatar T Makphaibulchoke Committed by Theodore Ts'o
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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: default avatarT. Makphaibulchoke <tmac@hp.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent b8a86845

fs/mbcache.c

+78 −39
Original line number Diff line number Diff line
@@ -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_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)

{

	if (__mb_cache_entry_is_hashed(ce)) {

		list_del_init(&ce->e_block_list);

		list_del(&ce->e_index.o_list);

	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;

}

include/linux/mbcache.h

+7 −5
Original line number Diff line number Diff line
@@ -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 */