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a38e4082 DC |
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); |