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 }; 129 /* this must be embedded in a deferred_request that is being 130 * delayed awaiting cache-fill 131 */ 132 struct cache_deferred_req { 133 struct list_head hash; /* on hash chain */ 134 struct list_head recent; /* on fifo */ 135 struct cache_head *item; /* cache item we wait on */ 136 void *owner; /* we might need to discard all defered requests 137 * owned by someone */ 138 void (*revisit)(struct cache_deferred_req *req, 139 int too_many); 140 }; 141 142 143 extern const struct file_operations cache_file_operations_pipefs; 144 extern const struct file_operations content_file_operations_pipefs; 145 extern const struct file_operations cache_flush_operations_pipefs; 146 147 extern struct cache_head * 148 sunrpc_cache_lookup(struct cache_detail *detail, 149 struct cache_head *key, int hash); 150 extern struct cache_head * 151 sunrpc_cache_update(struct cache_detail *detail, 152 struct cache_head *new, struct cache_head *old, int hash); 153 154 extern int 155 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h, 156 void (*cache_request)(struct cache_detail *, 157 struct cache_head *, 158 char **, 159 int *)); 160 161 162 extern void cache_clean_deferred(void *owner); 163 164 static inline struct cache_head *cache_get(struct cache_head *h) 165 { 166 kref_get(&h->ref); 167 return h; 168 } 169 170 171 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 172 { 173 if (atomic_read(&h->ref.refcount) <= 2 && 174 h->expiry_time < cd->nextcheck) 175 cd->nextcheck = h->expiry_time; 176 kref_put(&h->ref, cd->cache_put); 177 } 178 179 static inline int cache_valid(struct cache_head *h) 180 { 181 /* If an item has been unhashed pending removal when 182 * the refcount drops to 0, the expiry_time will be 183 * set to 0. We don't want to consider such items 184 * valid in this context even though CACHE_VALID is 185 * set. 186 */ 187 return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags)); 188 } 189 190 extern int cache_check(struct cache_detail *detail, 191 struct cache_head *h, struct cache_req *rqstp); 192 extern void cache_flush(void); 193 extern void cache_purge(struct cache_detail *detail); 194 #define NEVER (0x7FFFFFFF) 195 extern int cache_register(struct cache_detail *cd); 196 extern void cache_unregister(struct cache_detail *cd); 197 198 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 199 mode_t, struct cache_detail *); 200 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 201 202 extern void qword_add(char **bpp, int *lp, char *str); 203 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 204 extern int qword_get(char **bpp, char *dest, int bufsize); 205 206 static inline int get_int(char **bpp, int *anint) 207 { 208 char buf[50]; 209 char *ep; 210 int rv; 211 int len = qword_get(bpp, buf, 50); 212 if (len < 0) return -EINVAL; 213 if (len ==0) return -ENOENT; 214 rv = simple_strtol(buf, &ep, 0); 215 if (*ep) return -EINVAL; 216 *anint = rv; 217 return 0; 218 } 219 220 static inline time_t get_expiry(char **bpp) 221 { 222 int rv; 223 if (get_int(bpp, &rv)) 224 return 0; 225 if (rv < 0) 226 return 0; 227 return rv; 228 } 229 230 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 231