From a38e40824844a5ec85f3ea95632be953477d2afa Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 28 Aug 2013 10:17:58 +1000 Subject: list: add a new LRU list type MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Several subsystems use the same construct for LRU lists - a list head, a spin lock and and item count. They also use exactly the same code for adding and removing items from the LRU. Create a generic type for these LRU lists. This is the beginning of generic, node aware LRUs for shrinkers to work with. [glommer@openvz.org: enum defined constants for lru. Suggested by gthelen, don't relock over retry] Signed-off-by: Dave Chinner Signed-off-by: Glauber Costa Reviewed-by: Greg Thelen Acked-by: Mel Gorman Cc: "Theodore Ts'o" Cc: Adrian Hunter Cc: Al Viro Cc: Artem Bityutskiy Cc: Arve Hjønnevåg Cc: Carlos Maiolino Cc: Christoph Hellwig Cc: Chuck Lever Cc: Daniel Vetter Cc: David Rientjes Cc: Gleb Natapov Cc: Greg Thelen Cc: J. Bruce Fields Cc: Jan Kara Cc: Jerome Glisse Cc: John Stultz Cc: KAMEZAWA Hiroyuki Cc: Kent Overstreet Cc: Kirill A. Shutemov Cc: Marcelo Tosatti Cc: Mel Gorman Cc: Steven Whitehouse Cc: Thomas Hellstrom Cc: Trond Myklebust Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- mm/list_lru.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 117 insertions(+) create mode 100644 mm/list_lru.c (limited to 'mm/list_lru.c') 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 +#include +#include + +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); -- cgit v1.2.3