Edit File: list_lru.h
/* * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved. * Authors: David Chinner and Glauber Costa * * Generic LRU infrastructure */ #ifndef _LRU_LIST_H #define _LRU_LIST_H #include <linux/list.h> #include <linux/nodemask.h> /* list_lru_walk_cb has to always return one of those */ enum lru_status { LRU_REMOVED, /* item removed from list */ LRU_REMOVED_RETRY, /* item removed, but lock has been dropped and reacquired */ LRU_ROTATE, /* item referenced, give another pass */ LRU_SKIP, /* item cannot be locked, skip */ LRU_RETRY, /* item not freeable. May drop the lock internally, but has to return locked. */ }; struct list_lru_node { spinlock_t lock; struct list_head list; /* kept as signed so we can catch imbalance bugs */ long nr_items; } ____cacheline_aligned_in_smp; struct list_lru { struct list_lru_node *node; nodemask_t active_nodes; }; void list_lru_destroy(struct list_lru *lru); int list_lru_init_key(struct list_lru *lru, struct lock_class_key *key); static inline int list_lru_init(struct list_lru *lru) { return list_lru_init_key(lru, NULL); } /** * list_lru_add: add an element to the lru list's tail * @list_lru: the lru pointer * @item: the item to be added. * * If the element is already part of a list, this function returns doing * nothing. Therefore the caller does not need to keep state about whether or * not the element already belongs in the list and is allowed to lazy update * it. Note however that this is valid for *a* list, not *this* list. If * the caller organize itself in a way that elements can be in more than * one type of list, it is up to the caller to fully remove the item from * the previous list (with list_lru_del() for instance) before moving it * to @list_lru * * Return value: true if the list was updated, false otherwise */ bool list_lru_add(struct list_lru *lru, struct list_head *item); /** * list_lru_del: delete an element to the lru list * @list_lru: the lru pointer * @item: the item to be deleted. * * This function works analogously as list_lru_add in terms of list * manipulation. The comments about an element already pertaining to * a list are also valid for list_lru_del. * * Return value: true if the list was updated, false otherwise */ bool list_lru_del(struct list_lru *lru, struct list_head *item); /** * list_lru_count_node: return the number of objects currently held by @lru * @lru: the lru pointer. * @nid: the node id to count from. * * Always return a non-negative number, 0 for empty lists. There is no * guarantee that the list is not updated while the count is being computed. * Callers that want such a guarantee need to provide an outer lock. */ unsigned long list_lru_count_node(struct list_lru *lru, int nid); static inline unsigned long list_lru_count(struct list_lru *lru) { long count = 0; int nid; for_each_node_mask(nid, lru->active_nodes) count += list_lru_count_node(lru, nid); return count; } typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, spinlock_t *lock, void *cb_arg); /** * list_lru_walk_node: walk a list_lru, isolating and disposing freeable items. * @lru: the lru pointer. * @nid: the node id to scan from. * @isolate: callback function that is resposible for deciding what to do with * the item currently being scanned * @cb_arg: opaque type that will be passed to @isolate * @nr_to_walk: how many items to scan. * * This function will scan all elements in a particular list_lru, calling the * @isolate callback for each of those items, along with the current list * spinlock and a caller-provided opaque. The @isolate callback can choose to * drop the lock internally, but *must* return with the lock held. The callback * will return an enum lru_status telling the list_lru infrastructure what to * do with the object being scanned. * * Please note that nr_to_walk does not mean how many objects will be freed, * just how many objects will be scanned. * * Return value: the number of objects effectively removed from the LRU. */ unsigned long list_lru_walk_node(struct list_lru *lru, int nid, list_lru_walk_cb isolate, void *cb_arg, unsigned long *nr_to_walk); static inline unsigned long list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, void *cb_arg, unsigned long nr_to_walk) { long isolated = 0; int nid; for_each_node_mask(nid, lru->active_nodes) { isolated += list_lru_walk_node(lru, nid, isolate, cb_arg, &nr_to_walk); if (nr_to_walk <= 0) break; } return isolated; } #endif /* _LRU_LIST_H */