Dave Chinner | a38e408 | 2013-08-28 10:17:58 +1000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved. |
| 3 | * Authors: David Chinner and Glauber Costa |
| 4 | * |
| 5 | * Generic LRU infrastructure |
| 6 | */ |
| 7 | #include <linux/kernel.h> |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/list_lru.h> |
| 10 | |
| 11 | bool list_lru_add(struct list_lru *lru, struct list_head *item) |
| 12 | { |
| 13 | spin_lock(&lru->lock); |
| 14 | if (list_empty(item)) { |
| 15 | list_add_tail(item, &lru->list); |
| 16 | lru->nr_items++; |
| 17 | spin_unlock(&lru->lock); |
| 18 | return true; |
| 19 | } |
| 20 | spin_unlock(&lru->lock); |
| 21 | return false; |
| 22 | } |
| 23 | EXPORT_SYMBOL_GPL(list_lru_add); |
| 24 | |
| 25 | bool list_lru_del(struct list_lru *lru, struct list_head *item) |
| 26 | { |
| 27 | spin_lock(&lru->lock); |
| 28 | if (!list_empty(item)) { |
| 29 | list_del_init(item); |
| 30 | lru->nr_items--; |
| 31 | spin_unlock(&lru->lock); |
| 32 | return true; |
| 33 | } |
| 34 | spin_unlock(&lru->lock); |
| 35 | return false; |
| 36 | } |
| 37 | EXPORT_SYMBOL_GPL(list_lru_del); |
| 38 | |
| 39 | unsigned long list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, |
| 40 | void *cb_arg, unsigned long nr_to_walk) |
| 41 | { |
| 42 | struct list_head *item, *n; |
| 43 | unsigned long removed = 0; |
| 44 | /* |
| 45 | * If we don't keep state of at which pass we are, we can loop at |
| 46 | * LRU_RETRY, since we have no guarantees that the caller will be able |
| 47 | * to do something other than retry on the next pass. We handle this by |
| 48 | * allowing at most one retry per object. This should not be altered |
| 49 | * by any condition other than LRU_RETRY. |
| 50 | */ |
| 51 | bool first_pass = true; |
| 52 | |
| 53 | spin_lock(&lru->lock); |
| 54 | restart: |
| 55 | list_for_each_safe(item, n, &lru->list) { |
| 56 | enum lru_status ret; |
| 57 | ret = isolate(item, &lru->lock, cb_arg); |
| 58 | switch (ret) { |
| 59 | case LRU_REMOVED: |
| 60 | lru->nr_items--; |
| 61 | removed++; |
| 62 | break; |
| 63 | case LRU_ROTATE: |
| 64 | list_move_tail(item, &lru->list); |
| 65 | break; |
| 66 | case LRU_SKIP: |
| 67 | break; |
| 68 | case LRU_RETRY: |
| 69 | if (!first_pass) { |
| 70 | first_pass = true; |
| 71 | break; |
| 72 | } |
| 73 | first_pass = false; |
| 74 | goto restart; |
| 75 | default: |
| 76 | BUG(); |
| 77 | } |
| 78 | |
| 79 | if (nr_to_walk-- == 0) |
| 80 | break; |
| 81 | |
| 82 | } |
| 83 | spin_unlock(&lru->lock); |
| 84 | return removed; |
| 85 | } |
| 86 | EXPORT_SYMBOL_GPL(list_lru_walk); |
| 87 | |
| 88 | unsigned long list_lru_dispose_all(struct list_lru *lru, |
| 89 | list_lru_dispose_cb dispose) |
| 90 | { |
| 91 | unsigned long disposed = 0; |
| 92 | LIST_HEAD(dispose_list); |
| 93 | |
| 94 | spin_lock(&lru->lock); |
| 95 | while (!list_empty(&lru->list)) { |
| 96 | list_splice_init(&lru->list, &dispose_list); |
| 97 | disposed += lru->nr_items; |
| 98 | lru->nr_items = 0; |
| 99 | spin_unlock(&lru->lock); |
| 100 | |
| 101 | dispose(&dispose_list); |
| 102 | |
| 103 | spin_lock(&lru->lock); |
| 104 | } |
| 105 | spin_unlock(&lru->lock); |
| 106 | return disposed; |
| 107 | } |
| 108 | |
| 109 | int list_lru_init(struct list_lru *lru) |
| 110 | { |
| 111 | spin_lock_init(&lru->lock); |
| 112 | INIT_LIST_HEAD(&lru->list); |
| 113 | lru->nr_items = 0; |
| 114 | |
| 115 | return 0; |
| 116 | } |
| 117 | EXPORT_SYMBOL_GPL(list_lru_init); |