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 <[email protected]> 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 time64_t expiry_time; /* After time expiry_time, don't use 49 * the data */ 50 time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was 51 * sent, else this is when update was 52 * received, though it is alway set to 53 * be *after* ->flush_time. 54 */ 55 struct kref ref; 56 unsigned long flags; 57 }; 58 #define CACHE_VALID 0 /* Entry contains valid data */ 59 #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */ 60 #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/ 61 #define CACHE_CLEANED 3 /* Entry has been cleaned from cache */ 62 63 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ 64 65 struct cache_detail { 66 struct module * owner; 67 int hash_size; 68 struct hlist_head * hash_table; 69 spinlock_t hash_lock; 70 71 char *name; 72 void (*cache_put)(struct kref *); 73 74 int (*cache_upcall)(struct cache_detail *, 75 struct cache_head *); 76 77 void (*cache_request)(struct cache_detail *cd, 78 struct cache_head *ch, 79 char **bpp, int *blen); 80 81 int (*cache_parse)(struct cache_detail *, 82 char *buf, int len); 83 84 int (*cache_show)(struct seq_file *m, 85 struct cache_detail *cd, 86 struct cache_head *h); 87 void (*warn_no_listener)(struct cache_detail *cd, 88 int has_died); 89 90 struct cache_head * (*alloc)(void); 91 void (*flush)(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 time64_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 time64_t nextcheck; 107 int entries; 108 109 /* fields for communication over channel */ 110 struct list_head queue; 111 112 atomic_t writers; /* how many time is /channel open */ 113 time64_t last_close; /* if no writers, when did last close */ 114 time64_t last_warn; /* when we last warned about no writers */ 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 * This reimplemnts ktime_get_boottime_seconds() in a slightly 152 * faster but less accurate way. When we end up converting 153 * back to wallclock (CLOCK_REALTIME), that error often 154 * cancels out during the reverse operation. 155 */ 156 static inline time64_t seconds_since_boot(void) 157 { 158 struct timespec64 boot; 159 getboottime64(&boot); 160 return ktime_get_real_seconds() - boot.tv_sec; 161 } 162 163 static inline time64_t convert_to_wallclock(time64_t sinceboot) 164 { 165 struct timespec64 boot; 166 getboottime64(&boot); 167 return boot.tv_sec + sinceboot; 168 } 169 170 extern const struct file_operations cache_file_operations_pipefs; 171 extern const struct file_operations content_file_operations_pipefs; 172 extern const struct file_operations cache_flush_operations_pipefs; 173 174 extern struct cache_head * 175 sunrpc_cache_lookup_rcu(struct cache_detail *detail, 176 struct cache_head *key, int hash); 177 extern struct cache_head * 178 sunrpc_cache_update(struct cache_detail *detail, 179 struct cache_head *new, struct cache_head *old, int hash); 180 181 extern int 182 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h); 183 extern int 184 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail, 185 struct cache_head *h); 186 187 188 extern void cache_clean_deferred(void *owner); 189 190 static inline struct cache_head *cache_get(struct cache_head *h) 191 { 192 kref_get(&h->ref); 193 return h; 194 } 195 196 static inline struct cache_head *cache_get_rcu(struct cache_head *h) 197 { 198 if (kref_get_unless_zero(&h->ref)) 199 return h; 200 return NULL; 201 } 202 203 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 204 { 205 if (kref_read(&h->ref) <= 2 && 206 h->expiry_time < cd->nextcheck) 207 cd->nextcheck = h->expiry_time; 208 kref_put(&h->ref, cd->cache_put); 209 } 210 211 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) 212 { 213 if (h->expiry_time < seconds_since_boot()) 214 return true; 215 if (!test_bit(CACHE_VALID, &h->flags)) 216 return false; 217 return detail->flush_time >= h->last_refresh; 218 } 219 220 extern int cache_check(struct cache_detail *detail, 221 struct cache_head *h, struct cache_req *rqstp); 222 extern void cache_flush(void); 223 extern void cache_purge(struct cache_detail *detail); 224 #define NEVER (0x7FFFFFFF) 225 extern void __init cache_initialize(void); 226 extern int cache_register_net(struct cache_detail *cd, struct net *net); 227 extern void cache_unregister_net(struct cache_detail *cd, struct net *net); 228 229 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net); 230 extern void cache_destroy_net(struct cache_detail *cd, struct net *net); 231 232 extern void sunrpc_init_cache_detail(struct cache_detail *cd); 233 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd); 234 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 235 umode_t, struct cache_detail *); 236 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 237 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); 238 239 /* Must store cache_detail in seq_file->private if using next three functions */ 240 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); 241 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); 242 extern void cache_seq_stop_rcu(struct seq_file *file, void *p); 243 244 extern void qword_add(char **bpp, int *lp, char *str); 245 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 246 extern int qword_get(char **bpp, char *dest, int bufsize); 247 248 static inline int get_int(char **bpp, int *anint) 249 { 250 char buf[50]; 251 char *ep; 252 int rv; 253 int len = qword_get(bpp, buf, sizeof(buf)); 254 255 if (len < 0) 256 return -EINVAL; 257 if (len == 0) 258 return -ENOENT; 259 260 rv = simple_strtol(buf, &ep, 0); 261 if (*ep) 262 return -EINVAL; 263 264 *anint = rv; 265 return 0; 266 } 267 268 static inline int get_uint(char **bpp, unsigned int *anint) 269 { 270 char buf[50]; 271 int len = qword_get(bpp, buf, sizeof(buf)); 272 273 if (len < 0) 274 return -EINVAL; 275 if (len == 0) 276 return -ENOENT; 277 278 if (kstrtouint(buf, 0, anint)) 279 return -EINVAL; 280 281 return 0; 282 } 283 284 static inline int get_time(char **bpp, time64_t *time) 285 { 286 char buf[50]; 287 long long ll; 288 int len = qword_get(bpp, buf, sizeof(buf)); 289 290 if (len < 0) 291 return -EINVAL; 292 if (len == 0) 293 return -ENOENT; 294 295 if (kstrtoll(buf, 0, &ll)) 296 return -EINVAL; 297 298 *time = ll; 299 return 0; 300 } 301 302 static inline time64_t get_expiry(char **bpp) 303 { 304 time64_t rv; 305 struct timespec64 boot; 306 307 if (get_time(bpp, &rv)) 308 return 0; 309 if (rv < 0) 310 return 0; 311 getboottime64(&boot); 312 return rv - boot.tv_sec; 313 } 314 315 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 316