sunrpc: Switch to using hash list instead single list

Switch using list_head for cache_head in cache_detail,
it is useful of remove an cache_head entry directly from cache_detail.

v8, using hash list, not head list

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

include/linux/sunrpc/cache.h

@@ -46,7 +46,7 @@
  * 
  */
 struct cache_head {
-	struct cache_head * next;
+	struct hlist_node	cache_list;
 	time_t		expiry_time;	/* After time time, don't use the data */
 	time_t		last_refresh;   /* If CACHE_PENDING, this is when upcall 
 					 * was sent, else this is when update was received
@@ -73,7 +73,7 @@ struct cache_detail_pipefs {
 struct cache_detail {
 	struct module *		owner;
 	int			hash_size;
-	struct cache_head **	hash_table;
+	struct hlist_head *	hash_table;
 	rwlock_t		hash_lock;
 
 	atomic_t		inuse; /* active user-space update or lookup */

net/sunrpc/cache.c

@@ -44,7 +44,7 @@ static void cache_revisit_request(struct cache_head *item);
 static void cache_init(struct cache_head *h)
 {
 	time_t now = seconds_since_boot();
-	h->next = NULL;
+	INIT_HLIST_NODE(&h->cache_list);
 	h->flags = 0;
 	kref_init(&h->ref);
 	h->expiry_time = now + CACHE_NEW_EXPIRY;
@@ -54,15 +54,14 @@ static void cache_init(struct cache_head *h)
 struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
 				       struct cache_head *key, int hash)
 {
-	struct cache_head **head,  **hp;
-	struct cache_head *new = NULL, *freeme = NULL;
+	struct cache_head *new = NULL, *freeme = NULL, *tmp = NULL;
+	struct hlist_head *head;
 
 	head = &detail->hash_table[hash];
 
 	read_lock(&detail->hash_lock);
 
-	for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
-		struct cache_head *tmp = *hp;
+	hlist_for_each_entry(tmp, head, cache_list) {
 		if (detail->match(tmp, key)) {
 			if (cache_is_expired(detail, tmp))
 				/* This entry is expired, we will discard it. */
@@ -88,12 +87,10 @@ struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
 	write_lock(&detail->hash_lock);
 
 	/* check if entry appeared while we slept */
-	for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
-		struct cache_head *tmp = *hp;
+	hlist_for_each_entry(tmp, head, cache_list) {
 		if (detail->match(tmp, key)) {
 			if (cache_is_expired(detail, tmp)) {
-				*hp = tmp->next;
-				tmp->next = NULL;
+				hlist_del_init(&tmp->cache_list);
 				detail->entries --;
 				freeme = tmp;
 				break;
@@ -104,8 +101,8 @@ struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
 			return tmp;
 		}
 	}
-	new->next = *head;
-	*head = new;
+
+	hlist_add_head(&new->cache_list, head);
 	detail->entries++;
 	cache_get(new);
 	write_unlock(&detail->hash_lock);
@@ -143,7 +140,6 @@ struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 	 * If 'old' is not VALID, we update it directly,
 	 * otherwise we need to replace it
 	 */
-	struct cache_head **head;
 	struct cache_head *tmp;
 
 	if (!test_bit(CACHE_VALID, &old->flags)) {
@@ -168,15 +164,13 @@ struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 	}
 	cache_init(tmp);
 	detail->init(tmp, old);
-	head = &detail->hash_table[hash];
 
 	write_lock(&detail->hash_lock);
 	if (test_bit(CACHE_NEGATIVE, &new->flags))
 		set_bit(CACHE_NEGATIVE, &tmp->flags);
 	else
 		detail->update(tmp, new);
-	tmp->next = *head;
-	*head = tmp;
+	hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]);
 	detail->entries++;
 	cache_get(tmp);
 	cache_fresh_locked(tmp, new->expiry_time);
@@ -416,28 +410,29 @@ static int cache_clean(void)
 	/* find a non-empty bucket in the table */
 	while (current_detail &&
 	       current_index < current_detail->hash_size &&
-	       current_detail->hash_table[current_index] == NULL)
+	       hlist_empty(&current_detail->hash_table[current_index]))
 		current_index++;
 
 	/* find a cleanable entry in the bucket and clean it, or set to next bucket */
 
 	if (current_detail && current_index < current_detail->hash_size) {
-		struct cache_head *ch, **cp;
+		struct cache_head *ch = NULL;
 		struct cache_detail *d;
+		struct hlist_head *head;
+		struct hlist_node *tmp;
 
 		write_lock(&current_detail->hash_lock);
 
 		/* Ok, now to clean this strand */
 
-		cp = & current_detail->hash_table[current_index];
-		for (ch = *cp ; ch ; cp = & ch->next, ch = *cp) {
+		head = &current_detail->hash_table[current_index];
+		hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
 			if (current_detail->nextcheck > ch->expiry_time)
 				current_detail->nextcheck = ch->expiry_time+1;
 			if (!cache_is_expired(current_detail, ch))
 				continue;
 
-			*cp = ch->next;
-			ch->next = NULL;
+			hlist_del_init(&ch->cache_list);
 			current_detail->entries--;
 			rv = 1;
 			break;
@@ -1284,7 +1279,7 @@ void *cache_seq_start(struct seq_file *m, loff_t *pos)
 	hash = n >> 32;
 	entry = n & ((1LL<<32) - 1);
 
-	for (ch=cd->hash_table[hash]; ch; ch=ch->next)
+	hlist_for_each_entry(ch, &cd->hash_table[hash], cache_list)
 		if (!entry--)
 			return ch;
 	n &= ~((1LL<<32) - 1);
@@ -1292,11 +1287,12 @@ void *cache_seq_start(struct seq_file *m, loff_t *pos)
 		hash++;
 		n += 1LL<<32;
 	} while(hash < cd->hash_size &&
-		cd->hash_table[hash]==NULL);
+		hlist_empty(&cd->hash_table[hash]));
 	if (hash >= cd->hash_size)
 		return NULL;
 	*pos = n+1;
-	return cd->hash_table[hash];
+	return hlist_entry_safe(cd->hash_table[hash].first,
+				struct cache_head, cache_list);
 }
 EXPORT_SYMBOL_GPL(cache_seq_start);
 
@@ -1308,23 +1304,25 @@ void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos)
 
 	if (p == SEQ_START_TOKEN)
 		hash = 0;
-	else if (ch->next == NULL) {
+	else if (ch->cache_list.next == NULL) {
 		hash++;
 		*pos += 1LL<<32;
 	} else {
 		++*pos;
-		return ch->next;
+		return hlist_entry_safe(ch->cache_list.next,
+					struct cache_head, cache_list);
 	}
 	*pos &= ~((1LL<<32) - 1);
 	while (hash < cd->hash_size &&
-	       cd->hash_table[hash] == NULL) {
+	       hlist_empty(&cd->hash_table[hash])) {
 		hash++;
 		*pos += 1LL<<32;
 	}
 	if (hash >= cd->hash_size)
 		return NULL;
 	++*pos;
-	return cd->hash_table[hash];
+	return hlist_entry_safe(cd->hash_table[hash].first,
+				struct cache_head, cache_list);
 }
 EXPORT_SYMBOL_GPL(cache_seq_next);
 
@@ -1666,17 +1664,21 @@ EXPORT_SYMBOL_GPL(cache_unregister_net);
 struct cache_detail *cache_create_net(struct cache_detail *tmpl, struct net *net)
 {
 	struct cache_detail *cd;
+	int i;
 
 	cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL);
 	if (cd == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	cd->hash_table = kzalloc(cd->hash_size * sizeof(struct cache_head *),
+	cd->hash_table = kzalloc(cd->hash_size * sizeof(struct hlist_head),
 				 GFP_KERNEL);
 	if (cd->hash_table == NULL) {
 		kfree(cd);
 		return ERR_PTR(-ENOMEM);
 	}
+
+	for (i = 0; i < cd->hash_size; i++)
+		INIT_HLIST_HEAD(&cd->hash_table[i]);
 	cd->net = net;
 	return cd;
 }