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 <[email protected]> 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 */ 53 struct kref ref; 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 { 63 struct module * owner; 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; 71 void (*cache_put)(struct kref *); 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 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 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 }; 129 130 131 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); 137 138 139 extern void cache_clean_deferred(void *owner); 140 141 static inline struct cache_head *cache_get(struct cache_head *h) 142 { 143 kref_get(&h->ref); 144 return h; 145 } 146 147 148 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 149 { 150 if (atomic_read(&h->ref.refcount) <= 2 && 151 h->expiry_time < cd->nextcheck) 152 cd->nextcheck = h->expiry_time; 153 kref_put(&h->ref, cd->cache_put); 154 } 155 156 static inline int cache_valid(struct cache_head *h) 157 { 158 /* If an item has been unhashed pending removal when 159 * the refcount drops to 0, the expiry_time will be 160 * set to 0. We don't want to consider such items 161 * valid in this context even though CACHE_VALID is 162 * set. 163 */ 164 return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags)); 165 } 166 167 extern int cache_check(struct cache_detail *detail, 168 struct cache_head *h, struct cache_req *rqstp); 169 extern void cache_flush(void); 170 extern void cache_purge(struct cache_detail *detail); 171 #define NEVER (0x7FFFFFFF) 172 extern void cache_register(struct cache_detail *cd); 173 extern int cache_unregister(struct cache_detail *cd); 174 175 extern void qword_add(char **bpp, int *lp, char *str); 176 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 177 extern int qword_get(char **bpp, char *dest, int bufsize); 178 179 static inline int get_int(char **bpp, int *anint) 180 { 181 char buf[50]; 182 char *ep; 183 int rv; 184 int len = qword_get(bpp, buf, 50); 185 if (len < 0) return -EINVAL; 186 if (len ==0) return -ENOENT; 187 rv = simple_strtol(buf, &ep, 0); 188 if (*ep) return -EINVAL; 189 *anint = rv; 190 return 0; 191 } 192 193 static inline time_t get_expiry(char **bpp) 194 { 195 int rv; 196 if (get_int(bpp, &rv)) 197 return 0; 198 if (rv < 0) 199 return 0; 200 return rv; 201 } 202 203 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 204