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/kstrtox.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 existence 38 * in the hash table. 39 * We only expire entries when refcount is zero. 40 * Existence 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 hlist_node cache_list; 49 time64_t expiry_time; /* After time expiry_time, don't use 50 * the data */ 51 time64_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 void (*flush)(void); 93 int (*match)(struct cache_head *orig, struct cache_head *new); 94 void (*init)(struct cache_head *orig, struct cache_head *new); 95 void (*update)(struct cache_head *orig, struct cache_head *new); 96 97 /* fields below this comment are for internal use 98 * and should not be touched by cache owners 99 */ 100 time64_t flush_time; /* flush all cache items with 101 * last_refresh at or earlier 102 * than this. last_refresh 103 * is never set at or earlier 104 * than this. 105 */ 106 struct list_head others; 107 time64_t nextcheck; 108 int entries; 109 110 /* fields for communication over channel */ 111 struct list_head queue; 112 113 atomic_t writers; /* how many time is /channel open */ 114 time64_t last_close; /* if no writers, when did last close */ 115 time64_t last_warn; /* when we last warned about no writers */ 116 117 union { 118 struct proc_dir_entry *procfs; 119 struct dentry *pipefs; 120 }; 121 struct net *net; 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 unsigned long thread_wait; /* How long (jiffies) we can block the 131 * current thread to wait for updates. 132 */ 133 }; 134 135 /* this must be embedded in a deferred_request that is being 136 * delayed awaiting cache-fill 137 */ 138 struct cache_deferred_req { 139 struct hlist_node hash; /* on hash chain */ 140 struct list_head recent; /* on fifo */ 141 struct cache_head *item; /* cache item we wait on */ 142 void *owner; /* we might need to discard all defered requests 143 * owned by someone */ 144 void (*revisit)(struct cache_deferred_req *req, 145 int too_many); 146 }; 147 148 /* 149 * timestamps kept in the cache are expressed in seconds 150 * since boot. This is the best for measuring differences in 151 * real time. 152 * This reimplemnts ktime_get_boottime_seconds() in a slightly 153 * faster but less accurate way. When we end up converting 154 * back to wallclock (CLOCK_REALTIME), that error often 155 * cancels out during the reverse operation. 156 */ 157 static inline time64_t seconds_since_boot(void) 158 { 159 struct timespec64 boot; 160 getboottime64(&boot); 161 return ktime_get_real_seconds() - boot.tv_sec; 162 } 163 164 static inline time64_t convert_to_wallclock(time64_t sinceboot) 165 { 166 struct timespec64 boot; 167 getboottime64(&boot); 168 return boot.tv_sec + sinceboot; 169 } 170 171 extern const struct file_operations cache_file_operations_pipefs; 172 extern const struct file_operations content_file_operations_pipefs; 173 extern const struct file_operations cache_flush_operations_pipefs; 174 175 extern struct cache_head * 176 sunrpc_cache_lookup_rcu(struct cache_detail *detail, 177 struct cache_head *key, int hash); 178 extern struct cache_head * 179 sunrpc_cache_update(struct cache_detail *detail, 180 struct cache_head *new, struct cache_head *old, int hash); 181 182 extern int 183 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h); 184 extern int 185 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail, 186 struct cache_head *h); 187 188 189 extern void cache_clean_deferred(void *owner); 190 191 static inline struct cache_head *cache_get(struct cache_head *h) 192 { 193 kref_get(&h->ref); 194 return h; 195 } 196 197 static inline struct cache_head *cache_get_rcu(struct cache_head *h) 198 { 199 if (kref_get_unless_zero(&h->ref)) 200 return h; 201 return NULL; 202 } 203 204 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 205 { 206 if (kref_read(&h->ref) <= 2 && 207 h->expiry_time < cd->nextcheck) 208 cd->nextcheck = h->expiry_time; 209 kref_put(&h->ref, cd->cache_put); 210 } 211 212 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) 213 { 214 if (h->expiry_time < seconds_since_boot()) 215 return true; 216 if (!test_bit(CACHE_VALID, &h->flags)) 217 return false; 218 return detail->flush_time >= h->last_refresh; 219 } 220 221 extern int cache_check(struct cache_detail *detail, 222 struct cache_head *h, struct cache_req *rqstp); 223 extern void cache_flush(void); 224 extern void cache_purge(struct cache_detail *detail); 225 #define NEVER (0x7FFFFFFF) 226 extern void __init cache_initialize(void); 227 extern int cache_register_net(struct cache_detail *cd, struct net *net); 228 extern void cache_unregister_net(struct cache_detail *cd, struct net *net); 229 230 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net); 231 extern void cache_destroy_net(struct cache_detail *cd, struct net *net); 232 233 extern void sunrpc_init_cache_detail(struct cache_detail *cd); 234 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd); 235 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 236 umode_t, struct cache_detail *); 237 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 238 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); 239 240 /* Must store cache_detail in seq_file->private if using next three functions */ 241 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); 242 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); 243 extern void cache_seq_stop_rcu(struct seq_file *file, void *p); 244 245 extern void qword_add(char **bpp, int *lp, char *str); 246 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 247 extern int qword_get(char **bpp, char *dest, int bufsize); 248 249 static inline int get_int(char **bpp, int *anint) 250 { 251 char buf[50]; 252 char *ep; 253 int rv; 254 int len = qword_get(bpp, buf, sizeof(buf)); 255 256 if (len < 0) 257 return -EINVAL; 258 if (len == 0) 259 return -ENOENT; 260 261 rv = simple_strtol(buf, &ep, 0); 262 if (*ep) 263 return -EINVAL; 264 265 *anint = rv; 266 return 0; 267 } 268 269 static inline int get_uint(char **bpp, unsigned int *anint) 270 { 271 char buf[50]; 272 int len = qword_get(bpp, buf, sizeof(buf)); 273 274 if (len < 0) 275 return -EINVAL; 276 if (len == 0) 277 return -ENOENT; 278 279 if (kstrtouint(buf, 0, anint)) 280 return -EINVAL; 281 282 return 0; 283 } 284 285 static inline int get_time(char **bpp, time64_t *time) 286 { 287 char buf[50]; 288 long long ll; 289 int len = qword_get(bpp, buf, sizeof(buf)); 290 291 if (len < 0) 292 return -EINVAL; 293 if (len == 0) 294 return -ENOENT; 295 296 if (kstrtoll(buf, 0, &ll)) 297 return -EINVAL; 298 299 *time = ll; 300 return 0; 301 } 302 303 static inline int get_expiry(char **bpp, time64_t *rvp) 304 { 305 int error; 306 struct timespec64 boot; 307 308 error = get_time(bpp, rvp); 309 if (error) 310 return error; 311 312 getboottime64(&boot); 313 (*rvp) -= boot.tv_sec; 314 return 0; 315 } 316 317 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 318