1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * include/linux/sunrpc/cache.h 4 * 5 * Generic code for various authentication-related caches 6 * used by sunrpc clients and servers. 7 * 8 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au> 9 */ 10 11 #ifndef _LINUX_SUNRPC_CACHE_H_ 12 #define _LINUX_SUNRPC_CACHE_H_ 13 14 #include <linux/kref.h> 15 #include <linux/slab.h> 16 #include <linux/atomic.h> 17 #include <linux/proc_fs.h> 18 19 /* 20 * Each cache requires: 21 * - A 'struct cache_detail' which contains information specific to the cache 22 * for common code to use. 23 * - An item structure that must contain a "struct cache_head" 24 * - A lookup function defined using DefineCacheLookup 25 * - A 'put' function that can release a cache item. It will only 26 * be called after cache_put has succeed, so there are guarantee 27 * to be no references. 28 * - A function to calculate a hash of an item's key. 29 * 30 * as well as assorted code fragments (e.g. compare keys) and numbers 31 * (e.g. hash size, goal_age, etc). 32 * 33 * Each cache must be registered so that it can be cleaned regularly. 34 * When the cache is unregistered, it is flushed completely. 35 * 36 * Entries have a ref count and a 'hashed' flag which counts the existence 37 * in the hash table. 38 * We only expire entries when refcount is zero. 39 * Existence in the cache is counted the refcount. 40 */ 41 42 /* Every cache item has a common header that is used 43 * for expiring and refreshing entries. 44 * 45 */ 46 struct cache_head { 47 struct hlist_node cache_list; 48 time_t expiry_time; /* After time time, don't use the data */ 49 time_t last_refresh; /* If CACHE_PENDING, this is when upcall was 50 * sent, else this is when update was 51 * received, though it is alway set to 52 * be *after* ->flush_time. 53 */ 54 struct kref ref; 55 unsigned long flags; 56 }; 57 #define CACHE_VALID 0 /* Entry contains valid data */ 58 #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */ 59 #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/ 60 #define CACHE_CLEANED 3 /* Entry has been cleaned from cache */ 61 62 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ 63 64 struct cache_detail { 65 struct module * owner; 66 int hash_size; 67 struct hlist_head * hash_table; 68 spinlock_t hash_lock; 69 70 char *name; 71 void (*cache_put)(struct kref *); 72 73 int (*cache_upcall)(struct cache_detail *, 74 struct cache_head *); 75 76 void (*cache_request)(struct cache_detail *cd, 77 struct cache_head *ch, 78 char **bpp, int *blen); 79 80 int (*cache_parse)(struct cache_detail *, 81 char *buf, int len); 82 83 int (*cache_show)(struct seq_file *m, 84 struct cache_detail *cd, 85 struct cache_head *h); 86 void (*warn_no_listener)(struct cache_detail *cd, 87 int has_died); 88 89 struct cache_head * (*alloc)(void); 90 int (*match)(struct cache_head *orig, struct cache_head *new); 91 void (*init)(struct cache_head *orig, struct cache_head *new); 92 void (*update)(struct cache_head *orig, struct cache_head *new); 93 94 /* fields below this comment are for internal use 95 * and should not be touched by cache owners 96 */ 97 time_t flush_time; /* flush all cache items with 98 * last_refresh at or earlier 99 * than this. last_refresh 100 * is never set at or earlier 101 * than this. 102 */ 103 struct list_head others; 104 time_t nextcheck; 105 int entries; 106 107 /* fields for communication over channel */ 108 struct list_head queue; 109 110 atomic_t readers; /* how many time is /chennel open */ 111 time_t last_close; /* if no readers, when did last close */ 112 time_t last_warn; /* when we last warned about no readers */ 113 114 union { 115 struct proc_dir_entry *procfs; 116 struct dentry *pipefs; 117 }; 118 struct net *net; 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 * timestamps kept in the cache are expressed in seconds 147 * since boot. This is the best for measuring differences in 148 * real time. 149 */ 150 static inline time_t seconds_since_boot(void) 151 { 152 struct timespec boot; 153 getboottime(&boot); 154 return get_seconds() - boot.tv_sec; 155 } 156 157 static inline time_t convert_to_wallclock(time_t sinceboot) 158 { 159 struct timespec boot; 160 getboottime(&boot); 161 return boot.tv_sec + sinceboot; 162 } 163 164 extern const struct file_operations cache_file_operations_pipefs; 165 extern const struct file_operations content_file_operations_pipefs; 166 extern const struct file_operations cache_flush_operations_pipefs; 167 168 extern struct cache_head * 169 sunrpc_cache_lookup_rcu(struct cache_detail *detail, 170 struct cache_head *key, int hash); 171 extern struct cache_head * 172 sunrpc_cache_update(struct cache_detail *detail, 173 struct cache_head *new, struct cache_head *old, int hash); 174 175 extern int 176 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h); 177 178 179 extern void cache_clean_deferred(void *owner); 180 181 static inline struct cache_head *cache_get(struct cache_head *h) 182 { 183 kref_get(&h->ref); 184 return h; 185 } 186 187 static inline struct cache_head *cache_get_rcu(struct cache_head *h) 188 { 189 if (kref_get_unless_zero(&h->ref)) 190 return h; 191 return NULL; 192 } 193 194 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 195 { 196 if (kref_read(&h->ref) <= 2 && 197 h->expiry_time < cd->nextcheck) 198 cd->nextcheck = h->expiry_time; 199 kref_put(&h->ref, cd->cache_put); 200 } 201 202 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) 203 { 204 if (!test_bit(CACHE_VALID, &h->flags)) 205 return false; 206 207 return (h->expiry_time < seconds_since_boot()) || 208 (detail->flush_time >= h->last_refresh); 209 } 210 211 extern int cache_check(struct cache_detail *detail, 212 struct cache_head *h, struct cache_req *rqstp); 213 extern void cache_flush(void); 214 extern void cache_purge(struct cache_detail *detail); 215 #define NEVER (0x7FFFFFFF) 216 extern void __init cache_initialize(void); 217 extern int cache_register_net(struct cache_detail *cd, struct net *net); 218 extern void cache_unregister_net(struct cache_detail *cd, struct net *net); 219 220 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net); 221 extern void cache_destroy_net(struct cache_detail *cd, struct net *net); 222 223 extern void sunrpc_init_cache_detail(struct cache_detail *cd); 224 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd); 225 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 226 umode_t, struct cache_detail *); 227 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 228 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); 229 230 /* Must store cache_detail in seq_file->private if using next three functions */ 231 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); 232 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); 233 extern void cache_seq_stop_rcu(struct seq_file *file, void *p); 234 235 extern void qword_add(char **bpp, int *lp, char *str); 236 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 237 extern int qword_get(char **bpp, char *dest, int bufsize); 238 239 static inline int get_int(char **bpp, int *anint) 240 { 241 char buf[50]; 242 char *ep; 243 int rv; 244 int len = qword_get(bpp, buf, sizeof(buf)); 245 246 if (len < 0) 247 return -EINVAL; 248 if (len == 0) 249 return -ENOENT; 250 251 rv = simple_strtol(buf, &ep, 0); 252 if (*ep) 253 return -EINVAL; 254 255 *anint = rv; 256 return 0; 257 } 258 259 static inline int get_uint(char **bpp, unsigned int *anint) 260 { 261 char buf[50]; 262 int len = qword_get(bpp, buf, sizeof(buf)); 263 264 if (len < 0) 265 return -EINVAL; 266 if (len == 0) 267 return -ENOENT; 268 269 if (kstrtouint(buf, 0, anint)) 270 return -EINVAL; 271 272 return 0; 273 } 274 275 static inline int get_time(char **bpp, time_t *time) 276 { 277 char buf[50]; 278 long long ll; 279 int len = qword_get(bpp, buf, sizeof(buf)); 280 281 if (len < 0) 282 return -EINVAL; 283 if (len == 0) 284 return -ENOENT; 285 286 if (kstrtoll(buf, 0, &ll)) 287 return -EINVAL; 288 289 *time = (time_t)ll; 290 return 0; 291 } 292 293 static inline time_t get_expiry(char **bpp) 294 { 295 time_t rv; 296 struct timespec boot; 297 298 if (get_time(bpp, &rv)) 299 return 0; 300 if (rv < 0) 301 return 0; 302 getboottime(&boot); 303 return rv - boot.tv_sec; 304 } 305 306 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 307