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/*
* Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
* Authors: David Chinner and Glauber Costa
*
* Generic LRU infrastructure
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list_lru.h>
bool list_lru_add(struct list_lru *lru, struct list_head *item)
{
spin_lock(&lru->lock);
if (list_empty(item)) {
list_add_tail(item, &lru->list);
lru->nr_items++;
spin_unlock(&lru->lock);
return true;
}
spin_unlock(&lru->lock);
return false;
}
EXPORT_SYMBOL_GPL(list_lru_add);
bool list_lru_del(struct list_lru *lru, struct list_head *item)
{
spin_lock(&lru->lock);
if (!list_empty(item)) {
list_del_init(item);
lru->nr_items--;
spin_unlock(&lru->lock);
return true;
}
spin_unlock(&lru->lock);
return false;
}
EXPORT_SYMBOL_GPL(list_lru_del);
unsigned long list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
void *cb_arg, unsigned long nr_to_walk)
{
struct list_head *item, *n;
unsigned long removed = 0;
/*
* If we don't keep state of at which pass we are, we can loop at
* LRU_RETRY, since we have no guarantees that the caller will be able
* to do something other than retry on the next pass. We handle this by
* allowing at most one retry per object. This should not be altered
* by any condition other than LRU_RETRY.
*/
bool first_pass = true;
spin_lock(&lru->lock);
restart:
list_for_each_safe(item, n, &lru->list) {
enum lru_status ret;
ret = isolate(item, &lru->lock, cb_arg);
switch (ret) {
case LRU_REMOVED:
lru->nr_items--;
removed++;
break;
case LRU_ROTATE:
list_move_tail(item, &lru->list);
break;
case LRU_SKIP:
break;
case LRU_RETRY:
if (!first_pass) {
first_pass = true;
break;
}
first_pass = false;
goto restart;
default:
BUG();
}
if (nr_to_walk-- == 0)
break;
}
spin_unlock(&lru->lock);
return removed;
}
EXPORT_SYMBOL_GPL(list_lru_walk);
unsigned long list_lru_dispose_all(struct list_lru *lru,
list_lru_dispose_cb dispose)
{
unsigned long disposed = 0;
LIST_HEAD(dispose_list);
spin_lock(&lru->lock);
while (!list_empty(&lru->list)) {
list_splice_init(&lru->list, &dispose_list);
disposed += lru->nr_items;
lru->nr_items = 0;
spin_unlock(&lru->lock);
dispose(&dispose_list);
spin_lock(&lru->lock);
}
spin_unlock(&lru->lock);
return disposed;
}
int list_lru_init(struct list_lru *lru)
{
spin_lock_init(&lru->lock);
INIT_LIST_HEAD(&lru->list);
lru->nr_items = 0;
return 0;
}
EXPORT_SYMBOL_GPL(list_lru_init);
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