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1da177e4 LT |
1 | /* |
2 | * include/linux/sunrpc/cache.h | |
3 | * | |
4 | * Generic code for various authentication-related caches | |
5 | * used by sunrpc clients and servers. | |
6 | * | |
7 | * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au> | |
8 | * | |
9 | * Released under terms in GPL version 2. See COPYING. | |
10 | * | |
11 | */ | |
12 | ||
13 | #ifndef _LINUX_SUNRPC_CACHE_H_ | |
14 | #define _LINUX_SUNRPC_CACHE_H_ | |
15 | ||
16 | #include <linux/slab.h> | |
17 | #include <asm/atomic.h> | |
18 | #include <linux/proc_fs.h> | |
19 | ||
20 | /* | |
21 | * Each cache requires: | |
22 | * - A 'struct cache_detail' which contains information specific to the cache | |
23 | * for common code to use. | |
24 | * - An item structure that must contain a "struct cache_head" | |
25 | * - A lookup function defined using DefineCacheLookup | |
26 | * - A 'put' function that can release a cache item. It will only | |
27 | * be called after cache_put has succeed, so there are guarantee | |
28 | * to be no references. | |
29 | * - A function to calculate a hash of an item's key. | |
30 | * | |
31 | * as well as assorted code fragments (e.g. compare keys) and numbers | |
32 | * (e.g. hash size, goal_age, etc). | |
33 | * | |
34 | * Each cache must be registered so that it can be cleaned regularly. | |
35 | * When the cache is unregistered, it is flushed completely. | |
36 | * | |
37 | * Entries have a ref count and a 'hashed' flag which counts the existance | |
38 | * in the hash table. | |
39 | * We only expire entries when refcount is zero. | |
40 | * Existance in the cache is counted the refcount. | |
41 | */ | |
42 | ||
43 | /* Every cache item has a common header that is used | |
44 | * for expiring and refreshing entries. | |
45 | * | |
46 | */ | |
47 | struct cache_head { | |
48 | struct cache_head * next; | |
49 | time_t expiry_time; /* After time time, don't use the data */ | |
50 | time_t last_refresh; /* If CACHE_PENDING, this is when upcall | |
51 | * was sent, else this is when update was received | |
52 | */ | |
baab935f | 53 | struct kref ref; |
1da177e4 LT |
54 | unsigned long flags; |
55 | }; | |
56 | #define CACHE_VALID 0 /* Entry contains valid data */ | |
57 | #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */ | |
58 | #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/ | |
59 | ||
60 | #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ | |
61 | ||
62 | struct cache_detail { | |
f35279d3 | 63 | struct module * owner; |
1da177e4 LT |
64 | int hash_size; |
65 | struct cache_head ** hash_table; | |
66 | rwlock_t hash_lock; | |
67 | ||
68 | atomic_t inuse; /* active user-space update or lookup */ | |
69 | ||
70 | char *name; | |
baab935f | 71 | void (*cache_put)(struct kref *); |
1da177e4 LT |
72 | |
73 | void (*cache_request)(struct cache_detail *cd, | |
74 | struct cache_head *h, | |
75 | char **bpp, int *blen); | |
76 | int (*cache_parse)(struct cache_detail *, | |
77 | char *buf, int len); | |
78 | ||
79 | int (*cache_show)(struct seq_file *m, | |
80 | struct cache_detail *cd, | |
81 | struct cache_head *h); | |
82 | ||
15a5f6bd N |
83 | struct cache_head * (*alloc)(void); |
84 | int (*match)(struct cache_head *orig, struct cache_head *new); | |
85 | void (*init)(struct cache_head *orig, struct cache_head *new); | |
86 | void (*update)(struct cache_head *orig, struct cache_head *new); | |
87 | ||
1da177e4 LT |
88 | /* fields below this comment are for internal use |
89 | * and should not be touched by cache owners | |
90 | */ | |
91 | time_t flush_time; /* flush all cache items with last_refresh | |
92 | * earlier than this */ | |
93 | struct list_head others; | |
94 | time_t nextcheck; | |
95 | int entries; | |
96 | ||
97 | /* fields for communication over channel */ | |
98 | struct list_head queue; | |
99 | struct proc_dir_entry *proc_ent; | |
100 | struct proc_dir_entry *flush_ent, *channel_ent, *content_ent; | |
101 | ||
102 | atomic_t readers; /* how many time is /chennel open */ | |
103 | time_t last_close; /* if no readers, when did last close */ | |
104 | time_t last_warn; /* when we last warned about no readers */ | |
105 | void (*warn_no_listener)(struct cache_detail *cd); | |
106 | }; | |
107 | ||
108 | ||
109 | /* this must be embedded in any request structure that | |
110 | * identifies an object that will want a callback on | |
111 | * a cache fill | |
112 | */ | |
113 | struct cache_req { | |
114 | struct cache_deferred_req *(*defer)(struct cache_req *req); | |
115 | }; | |
116 | /* this must be embedded in a deferred_request that is being | |
117 | * delayed awaiting cache-fill | |
118 | */ | |
119 | struct cache_deferred_req { | |
120 | struct list_head hash; /* on hash chain */ | |
121 | struct list_head recent; /* on fifo */ | |
122 | struct cache_head *item; /* cache item we wait on */ | |
123 | time_t recv_time; | |
124 | void *owner; /* we might need to discard all defered requests | |
125 | * owned by someone */ | |
126 | void (*revisit)(struct cache_deferred_req *req, | |
127 | int too_many); | |
128 | }; | |
129 | ||
7d317f2c | 130 | |
15a5f6bd N |
131 | extern struct cache_head * |
132 | sunrpc_cache_lookup(struct cache_detail *detail, | |
133 | struct cache_head *key, int hash); | |
134 | extern struct cache_head * | |
135 | sunrpc_cache_update(struct cache_detail *detail, | |
136 | struct cache_head *new, struct cache_head *old, int hash); | |
137 | ||
1da177e4 LT |
138 | |
139 | #define cache_for_each(pos, detail, index, member) \ | |
140 | for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \ | |
141 | ({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \ | |
142 | ) \ | |
143 | for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \ | |
144 | &pos->member; \ | |
145 | pos = container_of(pos->member.next, typeof(*pos), member)) | |
146 | ||
147 | ||
148 | ||
149 | extern void cache_clean_deferred(void *owner); | |
150 | ||
151 | static inline struct cache_head *cache_get(struct cache_head *h) | |
152 | { | |
baab935f | 153 | kref_get(&h->ref); |
1da177e4 LT |
154 | return h; |
155 | } | |
156 | ||
157 | ||
baab935f | 158 | static inline void cache_put(struct cache_head *h, struct cache_detail *cd) |
1da177e4 | 159 | { |
baab935f | 160 | if (atomic_read(&h->ref.refcount) <= 2 && |
1da177e4 LT |
161 | h->expiry_time < cd->nextcheck) |
162 | cd->nextcheck = h->expiry_time; | |
baab935f | 163 | kref_put(&h->ref, cd->cache_put); |
1da177e4 LT |
164 | } |
165 | ||
7b2b1fee GB |
166 | static inline int cache_valid(struct cache_head *h) |
167 | { | |
168 | /* If an item has been unhashed pending removal when | |
169 | * the refcount drops to 0, the expiry_time will be | |
170 | * set to 0. We don't want to consider such items | |
171 | * valid in this context even though CACHE_VALID is | |
172 | * set. | |
173 | */ | |
174 | return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags)); | |
175 | } | |
176 | ||
1da177e4 LT |
177 | extern int cache_check(struct cache_detail *detail, |
178 | struct cache_head *h, struct cache_req *rqstp); | |
179 | extern void cache_flush(void); | |
180 | extern void cache_purge(struct cache_detail *detail); | |
181 | #define NEVER (0x7FFFFFFF) | |
182 | extern void cache_register(struct cache_detail *cd); | |
183 | extern int cache_unregister(struct cache_detail *cd); | |
184 | ||
185 | extern void qword_add(char **bpp, int *lp, char *str); | |
186 | extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); | |
187 | extern int qword_get(char **bpp, char *dest, int bufsize); | |
188 | ||
189 | static inline int get_int(char **bpp, int *anint) | |
190 | { | |
191 | char buf[50]; | |
192 | char *ep; | |
193 | int rv; | |
194 | int len = qword_get(bpp, buf, 50); | |
195 | if (len < 0) return -EINVAL; | |
196 | if (len ==0) return -ENOENT; | |
197 | rv = simple_strtol(buf, &ep, 0); | |
198 | if (*ep) return -EINVAL; | |
199 | *anint = rv; | |
200 | return 0; | |
201 | } | |
202 | ||
203 | static inline time_t get_expiry(char **bpp) | |
204 | { | |
205 | int rv; | |
206 | if (get_int(bpp, &rv)) | |
207 | return 0; | |
208 | if (rv < 0) | |
209 | return 0; | |
210 | return rv; | |
211 | } | |
212 | ||
213 | #endif /* _LINUX_SUNRPC_CACHE_H_ */ |