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/kref.h> 17 #include <linux/slab.h> 18 #include <linux/atomic.h> 19 #include <linux/proc_fs.h> 20 21 /* 22 * Each cache requires: 23 * - A 'struct cache_detail' which contains information specific to the cache 24 * for common code to use. 25 * - An item structure that must contain a "struct cache_head" 26 * - A lookup function defined using DefineCacheLookup 27 * - A 'put' function that can release a cache item. It will only 28 * be called after cache_put has succeed, so there are guarantee 29 * to be no references. 30 * - A function to calculate a hash of an item's key. 31 * 32 * as well as assorted code fragments (e.g. compare keys) and numbers 33 * (e.g. hash size, goal_age, etc). 34 * 35 * Each cache must be registered so that it can be cleaned regularly. 36 * When the cache is unregistered, it is flushed completely. 37 * 38 * Entries have a ref count and a 'hashed' flag which counts the existence 39 * in the hash table. 40 * We only expire entries when refcount is zero. 41 * Existence in the cache is counted the refcount. 42 */ 43 44 /* Every cache item has a common header that is used 45 * for expiring and refreshing entries. 46 * 47 */ 48 struct cache_head { 49 struct hlist_node cache_list; 50 time_t expiry_time; /* After time time, don't use the data */ 51 time_t last_refresh; /* If CACHE_PENDING, this is when upcall was 52 * sent, else this is when update was 53 * received, though it is alway set to 54 * be *after* ->flush_time. 55 */ 56 struct kref ref; 57 unsigned long flags; 58 }; 59 #define CACHE_VALID 0 /* Entry contains valid data */ 60 #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */ 61 #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/ 62 #define CACHE_CLEANED 3 /* Entry has been cleaned from cache */ 63 64 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ 65 66 struct cache_detail { 67 struct module * owner; 68 int hash_size; 69 struct hlist_head * hash_table; 70 spinlock_t hash_lock; 71 72 char *name; 73 void (*cache_put)(struct kref *); 74 75 int (*cache_upcall)(struct cache_detail *, 76 struct cache_head *); 77 78 void (*cache_request)(struct cache_detail *cd, 79 struct cache_head *ch, 80 char **bpp, int *blen); 81 82 int (*cache_parse)(struct cache_detail *, 83 char *buf, int len); 84 85 int (*cache_show)(struct seq_file *m, 86 struct cache_detail *cd, 87 struct cache_head *h); 88 void (*warn_no_listener)(struct cache_detail *cd, 89 int has_died); 90 91 struct cache_head * (*alloc)(void); 92 int (*match)(struct cache_head *orig, struct cache_head *new); 93 void (*init)(struct cache_head *orig, struct cache_head *new); 94 void (*update)(struct cache_head *orig, struct cache_head *new); 95 96 /* fields below this comment are for internal use 97 * and should not be touched by cache owners 98 */ 99 time_t flush_time; /* flush all cache items with 100 * last_refresh at or earlier 101 * than this. last_refresh 102 * is never set at or earlier 103 * than this. 104 */ 105 struct list_head others; 106 time_t nextcheck; 107 int entries; 108 109 /* fields for communication over channel */ 110 struct list_head queue; 111 112 atomic_t readers; /* how many time is /chennel open */ 113 time_t last_close; /* if no readers, when did last close */ 114 time_t last_warn; /* when we last warned about no readers */ 115 116 union { 117 struct proc_dir_entry *procfs; 118 struct dentry *pipefs; 119 }; 120 struct net *net; 121 }; 122 123 124 /* this must be embedded in any request structure that 125 * identifies an object that will want a callback on 126 * a cache fill 127 */ 128 struct cache_req { 129 struct cache_deferred_req *(*defer)(struct cache_req *req); 130 int thread_wait; /* How long (jiffies) we can block the 131 * current thread to wait for updates. 132 */ 133 }; 134 /* this must be embedded in a deferred_request that is being 135 * delayed awaiting cache-fill 136 */ 137 struct cache_deferred_req { 138 struct hlist_node hash; /* on hash chain */ 139 struct list_head recent; /* on fifo */ 140 struct cache_head *item; /* cache item we wait on */ 141 void *owner; /* we might need to discard all defered requests 142 * owned by someone */ 143 void (*revisit)(struct cache_deferred_req *req, 144 int too_many); 145 }; 146 147 /* 148 * timestamps kept in the cache are expressed in seconds 149 * since boot. This is the best for measuring differences in 150 * real time. 151 */ 152 static inline time_t seconds_since_boot(void) 153 { 154 struct timespec boot; 155 getboottime(&boot); 156 return get_seconds() - boot.tv_sec; 157 } 158 159 static inline time_t convert_to_wallclock(time_t sinceboot) 160 { 161 struct timespec boot; 162 getboottime(&boot); 163 return boot.tv_sec + sinceboot; 164 } 165 166 extern const struct file_operations cache_file_operations_pipefs; 167 extern const struct file_operations content_file_operations_pipefs; 168 extern const struct file_operations cache_flush_operations_pipefs; 169 170 extern struct cache_head * 171 sunrpc_cache_lookup_rcu(struct cache_detail *detail, 172 struct cache_head *key, int hash); 173 extern struct cache_head * 174 sunrpc_cache_update(struct cache_detail *detail, 175 struct cache_head *new, struct cache_head *old, int hash); 176 177 extern int 178 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h); 179 180 181 extern void cache_clean_deferred(void *owner); 182 183 static inline struct cache_head *cache_get(struct cache_head *h) 184 { 185 kref_get(&h->ref); 186 return h; 187 } 188 189 static inline struct cache_head *cache_get_rcu(struct cache_head *h) 190 { 191 if (kref_get_unless_zero(&h->ref)) 192 return h; 193 return NULL; 194 } 195 196 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 197 { 198 if (kref_read(&h->ref) <= 2 && 199 h->expiry_time < cd->nextcheck) 200 cd->nextcheck = h->expiry_time; 201 kref_put(&h->ref, cd->cache_put); 202 } 203 204 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) 205 { 206 if (!test_bit(CACHE_VALID, &h->flags)) 207 return false; 208 209 return (h->expiry_time < seconds_since_boot()) || 210 (detail->flush_time >= h->last_refresh); 211 } 212 213 extern int cache_check(struct cache_detail *detail, 214 struct cache_head *h, struct cache_req *rqstp); 215 extern void cache_flush(void); 216 extern void cache_purge(struct cache_detail *detail); 217 #define NEVER (0x7FFFFFFF) 218 extern void __init cache_initialize(void); 219 extern int cache_register_net(struct cache_detail *cd, struct net *net); 220 extern void cache_unregister_net(struct cache_detail *cd, struct net *net); 221 222 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net); 223 extern void cache_destroy_net(struct cache_detail *cd, struct net *net); 224 225 extern void sunrpc_init_cache_detail(struct cache_detail *cd); 226 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd); 227 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 228 umode_t, struct cache_detail *); 229 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 230 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); 231 232 /* Must store cache_detail in seq_file->private if using next three functions */ 233 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); 234 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); 235 extern void cache_seq_stop_rcu(struct seq_file *file, void *p); 236 237 extern void qword_add(char **bpp, int *lp, char *str); 238 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 239 extern int qword_get(char **bpp, char *dest, int bufsize); 240 241 static inline int get_int(char **bpp, int *anint) 242 { 243 char buf[50]; 244 char *ep; 245 int rv; 246 int len = qword_get(bpp, buf, sizeof(buf)); 247 248 if (len < 0) 249 return -EINVAL; 250 if (len == 0) 251 return -ENOENT; 252 253 rv = simple_strtol(buf, &ep, 0); 254 if (*ep) 255 return -EINVAL; 256 257 *anint = rv; 258 return 0; 259 } 260 261 static inline int get_uint(char **bpp, unsigned int *anint) 262 { 263 char buf[50]; 264 int len = qword_get(bpp, buf, sizeof(buf)); 265 266 if (len < 0) 267 return -EINVAL; 268 if (len == 0) 269 return -ENOENT; 270 271 if (kstrtouint(buf, 0, anint)) 272 return -EINVAL; 273 274 return 0; 275 } 276 277 static inline int get_time(char **bpp, time_t *time) 278 { 279 char buf[50]; 280 long long ll; 281 int len = qword_get(bpp, buf, sizeof(buf)); 282 283 if (len < 0) 284 return -EINVAL; 285 if (len == 0) 286 return -ENOENT; 287 288 if (kstrtoll(buf, 0, &ll)) 289 return -EINVAL; 290 291 *time = (time_t)ll; 292 return 0; 293 } 294 295 static inline time_t get_expiry(char **bpp) 296 { 297 time_t rv; 298 struct timespec boot; 299 300 if (get_time(bpp, &rv)) 301 return 0; 302 if (rv < 0) 303 return 0; 304 getboottime(&boot); 305 return rv - boot.tv_sec; 306 } 307 308 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 309