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 atomic_t refcnt; 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 cache_head *, 72 struct cache_detail*); 73 74 void (*cache_request)(struct cache_detail *cd, 75 struct cache_head *h, 76 char **bpp, int *blen); 77 int (*cache_parse)(struct cache_detail *, 78 char *buf, int len); 79 80 int (*cache_show)(struct seq_file *m, 81 struct cache_detail *cd, 82 struct cache_head *h); 83 84 /* fields below this comment are for internal use 85 * and should not be touched by cache owners 86 */ 87 time_t flush_time; /* flush all cache items with last_refresh 88 * earlier than this */ 89 struct list_head others; 90 time_t nextcheck; 91 int entries; 92 93 /* fields for communication over channel */ 94 struct list_head queue; 95 struct proc_dir_entry *proc_ent; 96 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent; 97 98 atomic_t readers; /* how many time is /chennel open */ 99 time_t last_close; /* if no readers, when did last close */ 100 time_t last_warn; /* when we last warned about no readers */ 101 void (*warn_no_listener)(struct cache_detail *cd); 102 }; 103 104 105 /* this must be embedded in any request structure that 106 * identifies an object that will want a callback on 107 * a cache fill 108 */ 109 struct cache_req { 110 struct cache_deferred_req *(*defer)(struct cache_req *req); 111 }; 112 /* this must be embedded in a deferred_request that is being 113 * delayed awaiting cache-fill 114 */ 115 struct cache_deferred_req { 116 struct list_head hash; /* on hash chain */ 117 struct list_head recent; /* on fifo */ 118 struct cache_head *item; /* cache item we wait on */ 119 time_t recv_time; 120 void *owner; /* we might need to discard all defered requests 121 * owned by someone */ 122 void (*revisit)(struct cache_deferred_req *req, 123 int too_many); 124 }; 125 126 /* 127 * just like a template in C++, this macro does cache lookup 128 * for us. 129 * The function is passed some sort of HANDLE from which a cache_detail 130 * structure can be determined (via SETUP, DETAIL), a template 131 * cache entry (type RTN*), and a "set" flag. Using the HASHFN and the 132 * TEST, the function will try to find a matching cache entry in the cache. 133 * If "set" == 0 : 134 * If an entry is found, it is returned 135 * If no entry is found, a new non-VALID entry is created. 136 * If "set" == 1 and INPLACE == 0 : 137 * If no entry is found a new one is inserted with data from "template" 138 * If a non-CACHE_VALID entry is found, it is updated from template using UPDATE 139 * If a CACHE_VALID entry is found, a new entry is swapped in with data 140 * from "template" 141 * If set == 1, and INPLACE == 1 : 142 * As above, except that if a CACHE_VALID entry is found, we UPDATE in place 143 * instead of swapping in a new entry. 144 * 145 * If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not 146 * run but insteead CACHE_NEGATIVE is set in any new item. 147 148 * In any case, the new entry is returned with a reference count. 149 * 150 * 151 * RTN is a struct type for a cache entry 152 * MEMBER is the member of the cache which is cache_head, which must be first 153 * FNAME is the name for the function 154 * ARGS are arguments to function and must contain RTN *item, int set. May 155 * also contain something to be usedby SETUP or DETAIL to find cache_detail. 156 * SETUP locates the cache detail and makes it available as... 157 * DETAIL identifies the cache detail, possibly set up by SETUP 158 * HASHFN returns a hash value of the cache entry "item" 159 * TEST tests if "tmp" matches "item" 160 * INIT copies key information from "item" to "new" 161 * UPDATE copies content information from "item" to "tmp" 162 * INPLACE is true if updates can happen inplace rather than allocating a new structure 163 * 164 * WARNING: any substantial changes to this must be reflected in 165 * net/sunrpc/svcauth.c(auth_domain_lookup) 166 * which is a similar routine that is open-coded. 167 */ 168 #define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \ 169 RTN *FNAME ARGS \ 170 { \ 171 RTN *tmp, *new=NULL; \ 172 struct cache_head **hp, **head; \ 173 SETUP; \ 174 head = &(DETAIL)->hash_table[HASHFN]; \ 175 retry: \ 176 if (set||new) write_lock(&(DETAIL)->hash_lock); \ 177 else read_lock(&(DETAIL)->hash_lock); \ 178 for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \ 179 tmp = container_of(*hp, RTN, MEMBER); \ 180 if (TEST) { /* found a match */ \ 181 \ 182 if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \ 183 break; \ 184 \ 185 if (new) \ 186 {INIT;} \ 187 if (set) { \ 188 if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\ 189 { /* need to swap in new */ \ 190 RTN *t2; \ 191 \ 192 new->MEMBER.next = tmp->MEMBER.next; \ 193 *hp = &new->MEMBER; \ 194 tmp->MEMBER.next = NULL; \ 195 t2 = tmp; tmp = new; new = t2; \ 196 } \ 197 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \ 198 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ 199 else { \ 200 UPDATE; \ 201 clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ 202 } \ 203 } \ 204 cache_get(&tmp->MEMBER); \ 205 if (set||new) write_unlock(&(DETAIL)->hash_lock); \ 206 else read_unlock(&(DETAIL)->hash_lock); \ 207 if (set) \ 208 cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \ 209 if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \ 210 if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \ 211 return tmp; \ 212 } \ 213 } \ 214 /* Didn't find anything */ \ 215 if (new) { \ 216 INIT; \ 217 new->MEMBER.next = *head; \ 218 *head = &new->MEMBER; \ 219 (DETAIL)->entries ++; \ 220 cache_get(&new->MEMBER); \ 221 if (set) { \ 222 tmp = new; \ 223 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \ 224 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ 225 else {UPDATE;} \ 226 } \ 227 } \ 228 if (set||new) write_unlock(&(DETAIL)->hash_lock); \ 229 else read_unlock(&(DETAIL)->hash_lock); \ 230 if (new && set) \ 231 cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \ 232 if (new) \ 233 return new; \ 234 new = kmalloc(sizeof(*new), GFP_KERNEL); \ 235 if (new) { \ 236 cache_init(&new->MEMBER); \ 237 goto retry; \ 238 } \ 239 return NULL; \ 240 } 241 242 #define DefineSimpleCacheLookup(STRUCT,INPLACE) \ 243 DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT *item, int set), /*no setup */, \ 244 & STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\ 245 STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE) 246 247 #define cache_for_each(pos, detail, index, member) \ 248 for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \ 249 ({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \ 250 ) \ 251 for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \ 252 &pos->member; \ 253 pos = container_of(pos->member.next, typeof(*pos), member)) 254 255 256 257 extern void cache_clean_deferred(void *owner); 258 259 static inline struct cache_head *cache_get(struct cache_head *h) 260 { 261 atomic_inc(&h->refcnt); 262 return h; 263 } 264 265 266 static inline int cache_put(struct cache_head *h, struct cache_detail *cd) 267 { 268 if (atomic_read(&h->refcnt) <= 2 && 269 h->expiry_time < cd->nextcheck) 270 cd->nextcheck = h->expiry_time; 271 return atomic_dec_and_test(&h->refcnt); 272 } 273 274 extern void cache_init(struct cache_head *h); 275 extern void cache_fresh(struct cache_detail *detail, 276 struct cache_head *head, time_t expiry); 277 extern int cache_check(struct cache_detail *detail, 278 struct cache_head *h, struct cache_req *rqstp); 279 extern void cache_flush(void); 280 extern void cache_purge(struct cache_detail *detail); 281 #define NEVER (0x7FFFFFFF) 282 extern void cache_register(struct cache_detail *cd); 283 extern int cache_unregister(struct cache_detail *cd); 284 285 extern void qword_add(char **bpp, int *lp, char *str); 286 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 287 extern int qword_get(char **bpp, char *dest, int bufsize); 288 289 static inline int get_int(char **bpp, int *anint) 290 { 291 char buf[50]; 292 char *ep; 293 int rv; 294 int len = qword_get(bpp, buf, 50); 295 if (len < 0) return -EINVAL; 296 if (len ==0) return -ENOENT; 297 rv = simple_strtol(buf, &ep, 0); 298 if (*ep) return -EINVAL; 299 *anint = rv; 300 return 0; 301 } 302 303 static inline time_t get_expiry(char **bpp) 304 { 305 int rv; 306 if (get_int(bpp, &rv)) 307 return 0; 308 if (rv < 0) 309 return 0; 310 return rv; 311 } 312 313 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 314