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-rw-r--r--mm/list_lru.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/mm/list_lru.c b/mm/list_lru.c
new file mode 100644
index 000000000000..dd74c5434cd8
--- /dev/null
+++ b/mm/list_lru.c
@@ -0,0 +1,117 @@
+/*
+ * 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);