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_procfs { 63 struct proc_dir_entry *proc_ent; 64 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent; 65 }; 66 67 struct cache_detail_pipefs { 68 struct dentry *dir; 69 }; 70 71 struct cache_detail { 72 struct module * owner; 73 int hash_size; 74 struct cache_head ** hash_table; 75 rwlock_t hash_lock; 76 77 atomic_t inuse; /* active user-space update or lookup */ 78 79 char *name; 80 void (*cache_put)(struct kref *); 81 82 int (*cache_upcall)(struct cache_detail *, 83 struct cache_head *); 84 85 int (*cache_parse)(struct cache_detail *, 86 char *buf, int len); 87 88 int (*cache_show)(struct seq_file *m, 89 struct cache_detail *cd, 90 struct cache_head *h); 91 void (*warn_no_listener)(struct cache_detail *cd, 92 int has_died); 93 94 struct cache_head * (*alloc)(void); 95 int (*match)(struct cache_head *orig, struct cache_head *new); 96 void (*init)(struct cache_head *orig, struct cache_head *new); 97 void (*update)(struct cache_head *orig, struct cache_head *new); 98 99 /* fields below this comment are for internal use 100 * and should not be touched by cache owners 101 */ 102 time_t flush_time; /* flush all cache items with last_refresh 103 * earlier than this */ 104 struct list_head others; 105 time_t nextcheck; 106 int entries; 107 108 /* fields for communication over channel */ 109 struct list_head queue; 110 111 atomic_t readers; /* how many time is /chennel open */ 112 time_t last_close; /* if no readers, when did last close */ 113 time_t last_warn; /* when we last warned about no readers */ 114 115 union { 116 struct cache_detail_procfs procfs; 117 struct cache_detail_pipefs pipefs; 118 } u; 119 }; 120 121 122 /* this must be embedded in any request structure that 123 * identifies an object that will want a callback on 124 * a cache fill 125 */ 126 struct cache_req { 127 struct cache_deferred_req *(*defer)(struct cache_req *req); 128 int thread_wait; /* How long (jiffies) we can block the 129 * current thread to wait for updates. 130 */ 131 }; 132 /* this must be embedded in a deferred_request that is being 133 * delayed awaiting cache-fill 134 */ 135 struct cache_deferred_req { 136 struct hlist_node hash; /* on hash chain */ 137 struct list_head recent; /* on fifo */ 138 struct cache_head *item; /* cache item we wait on */ 139 void *owner; /* we might need to discard all defered requests 140 * owned by someone */ 141 void (*revisit)(struct cache_deferred_req *req, 142 int too_many); 143 }; 144 145 146 extern const struct file_operations cache_file_operations_pipefs; 147 extern const struct file_operations content_file_operations_pipefs; 148 extern const struct file_operations cache_flush_operations_pipefs; 149 150 extern struct cache_head * 151 sunrpc_cache_lookup(struct cache_detail *detail, 152 struct cache_head *key, int hash); 153 extern struct cache_head * 154 sunrpc_cache_update(struct cache_detail *detail, 155 struct cache_head *new, struct cache_head *old, int hash); 156 157 extern int 158 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h, 159 void (*cache_request)(struct cache_detail *, 160 struct cache_head *, 161 char **, 162 int *)); 163 164 165 extern void cache_clean_deferred(void *owner); 166 167 static inline struct cache_head *cache_get(struct cache_head *h) 168 { 169 kref_get(&h->ref); 170 return h; 171 } 172 173 174 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 175 { 176 if (atomic_read(&h->ref.refcount) <= 2 && 177 h->expiry_time < cd->nextcheck) 178 cd->nextcheck = h->expiry_time; 179 kref_put(&h->ref, cd->cache_put); 180 } 181 182 static inline int cache_valid(struct cache_head *h) 183 { 184 /* If an item has been unhashed pending removal when 185 * the refcount drops to 0, the expiry_time will be 186 * set to 0. We don't want to consider such items 187 * valid in this context even though CACHE_VALID is 188 * set. 189 */ 190 return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags)); 191 } 192 193 extern int cache_check(struct cache_detail *detail, 194 struct cache_head *h, struct cache_req *rqstp); 195 extern void cache_flush(void); 196 extern void cache_purge(struct cache_detail *detail); 197 #define NEVER (0x7FFFFFFF) 198 extern void __init cache_initialize(void); 199 extern int cache_register(struct cache_detail *cd); 200 extern int cache_register_net(struct cache_detail *cd, struct net *net); 201 extern void cache_unregister(struct cache_detail *cd); 202 extern void cache_unregister_net(struct cache_detail *cd, struct net *net); 203 204 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 205 mode_t, struct cache_detail *); 206 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 207 208 extern void qword_add(char **bpp, int *lp, char *str); 209 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 210 extern int qword_get(char **bpp, char *dest, int bufsize); 211 212 static inline int get_int(char **bpp, int *anint) 213 { 214 char buf[50]; 215 char *ep; 216 int rv; 217 int len = qword_get(bpp, buf, 50); 218 if (len < 0) return -EINVAL; 219 if (len ==0) return -ENOENT; 220 rv = simple_strtol(buf, &ep, 0); 221 if (*ep) return -EINVAL; 222 *anint = rv; 223 return 0; 224 } 225 226 /* 227 * timestamps kept in the cache are expressed in seconds 228 * since boot. This is the best for measuring differences in 229 * real time. 230 */ 231 static inline time_t seconds_since_boot(void) 232 { 233 struct timespec boot; 234 getboottime(&boot); 235 return get_seconds() - boot.tv_sec; 236 } 237 238 static inline time_t convert_to_wallclock(time_t sinceboot) 239 { 240 struct timespec boot; 241 getboottime(&boot); 242 return boot.tv_sec + sinceboot; 243 } 244 245 static inline time_t get_expiry(char **bpp) 246 { 247 int rv; 248 struct timespec boot; 249 250 if (get_int(bpp, &rv)) 251 return 0; 252 if (rv < 0) 253 return 0; 254 getboottime(&boot); 255 return rv - boot.tv_sec; 256 } 257 258 static inline void sunrpc_invalidate(struct cache_head *h, 259 struct cache_detail *detail) 260 { 261 h->expiry_time = seconds_since_boot() - 1; 262 detail->nextcheck = seconds_since_boot(); 263 } 264 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 265