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 60 /* cache_head.flags */ 61 enum { 62 CACHE_VALID, /* Entry contains valid data */ 63 CACHE_NEGATIVE, /* Negative entry - there is no match for the key */ 64 CACHE_PENDING, /* An upcall has been sent but no reply received yet*/ 65 CACHE_CLEANED, /* Entry has been cleaned from cache */ 66 }; 67 68 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ 69 70 struct cache_detail { 71 struct module * owner; 72 int hash_size; 73 struct hlist_head * hash_table; 74 spinlock_t hash_lock; 75 76 char *name; 77 void (*cache_put)(struct kref *); 78 79 int (*cache_upcall)(struct cache_detail *, 80 struct cache_head *); 81 82 void (*cache_request)(struct cache_detail *cd, 83 struct cache_head *ch, 84 char **bpp, int *blen); 85 86 int (*cache_parse)(struct cache_detail *, 87 char *buf, int len); 88 89 int (*cache_show)(struct seq_file *m, 90 struct cache_detail *cd, 91 struct cache_head *h); 92 void (*warn_no_listener)(struct cache_detail *cd, 93 int has_died); 94 95 struct cache_head * (*alloc)(void); 96 void (*flush)(void); 97 int (*match)(struct cache_head *orig, struct cache_head *new); 98 void (*init)(struct cache_head *orig, struct cache_head *new); 99 void (*update)(struct cache_head *orig, struct cache_head *new); 100 101 /* fields below this comment are for internal use 102 * and should not be touched by cache owners 103 */ 104 time64_t flush_time; /* flush all cache items with 105 * last_refresh at or earlier 106 * than this. last_refresh 107 * is never set at or earlier 108 * than this. 109 */ 110 struct list_head others; 111 time64_t nextcheck; 112 int entries; 113 114 /* fields for communication over channel */ 115 struct list_head queue; 116 117 atomic_t writers; /* how many time is /channel open */ 118 time64_t last_close; /* if no writers, when did last close */ 119 time64_t last_warn; /* when we last warned about no writers */ 120 121 union { 122 struct proc_dir_entry *procfs; 123 struct dentry *pipefs; 124 }; 125 struct net *net; 126 }; 127 128 /* this must be embedded in any request structure that 129 * identifies an object that will want a callback on 130 * a cache fill 131 */ 132 struct cache_req { 133 struct cache_deferred_req *(*defer)(struct cache_req *req); 134 unsigned long thread_wait; /* How long (jiffies) we can block the 135 * current thread to wait for updates. 136 */ 137 }; 138 139 /* this must be embedded in a deferred_request that is being 140 * delayed awaiting cache-fill 141 */ 142 struct cache_deferred_req { 143 struct hlist_node hash; /* on hash chain */ 144 struct list_head recent; /* on fifo */ 145 struct cache_head *item; /* cache item we wait on */ 146 void *owner; /* we might need to discard all defered requests 147 * owned by someone */ 148 void (*revisit)(struct cache_deferred_req *req, 149 int too_many); 150 }; 151 152 /* 153 * timestamps kept in the cache are expressed in seconds 154 * since boot. This is the best for measuring differences in 155 * real time. 156 * This reimplemnts ktime_get_boottime_seconds() in a slightly 157 * faster but less accurate way. When we end up converting 158 * back to wallclock (CLOCK_REALTIME), that error often 159 * cancels out during the reverse operation. 160 */ 161 static inline time64_t seconds_since_boot(void) 162 { 163 struct timespec64 boot; 164 getboottime64(&boot); 165 return ktime_get_real_seconds() - boot.tv_sec; 166 } 167 168 static inline time64_t convert_to_wallclock(time64_t sinceboot) 169 { 170 struct timespec64 boot; 171 getboottime64(&boot); 172 return boot.tv_sec + sinceboot; 173 } 174 175 extern const struct file_operations cache_file_operations_pipefs; 176 extern const struct file_operations content_file_operations_pipefs; 177 extern const struct file_operations cache_flush_operations_pipefs; 178 179 extern struct cache_head * 180 sunrpc_cache_lookup_rcu(struct cache_detail *detail, 181 struct cache_head *key, int hash); 182 extern struct cache_head * 183 sunrpc_cache_update(struct cache_detail *detail, 184 struct cache_head *new, struct cache_head *old, int hash); 185 186 extern int 187 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h); 188 extern int 189 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail, 190 struct cache_head *h); 191 192 193 extern void cache_clean_deferred(void *owner); 194 195 static inline struct cache_head *cache_get(struct cache_head *h) 196 { 197 kref_get(&h->ref); 198 return h; 199 } 200 201 static inline struct cache_head *cache_get_rcu(struct cache_head *h) 202 { 203 if (kref_get_unless_zero(&h->ref)) 204 return h; 205 return NULL; 206 } 207 208 static inline void cache_put(struct cache_head *h, struct cache_detail *cd) 209 { 210 if (kref_read(&h->ref) <= 2 && 211 h->expiry_time < cd->nextcheck) 212 cd->nextcheck = h->expiry_time; 213 kref_put(&h->ref, cd->cache_put); 214 } 215 216 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) 217 { 218 if (h->expiry_time < seconds_since_boot()) 219 return true; 220 if (!test_bit(CACHE_VALID, &h->flags)) 221 return false; 222 return detail->flush_time >= h->last_refresh; 223 } 224 225 extern int cache_check_rcu(struct cache_detail *detail, 226 struct cache_head *h, struct cache_req *rqstp); 227 extern int cache_check(struct cache_detail *detail, 228 struct cache_head *h, struct cache_req *rqstp); 229 extern void cache_flush(void); 230 extern void cache_purge(struct cache_detail *detail); 231 #define NEVER (0x7FFFFFFF) 232 extern void __init cache_initialize(void); 233 extern int cache_register_net(struct cache_detail *cd, struct net *net); 234 extern void cache_unregister_net(struct cache_detail *cd, struct net *net); 235 236 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net); 237 extern void cache_destroy_net(struct cache_detail *cd, struct net *net); 238 239 extern void sunrpc_init_cache_detail(struct cache_detail *cd); 240 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd); 241 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, 242 umode_t, struct cache_detail *); 243 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); 244 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); 245 246 /* Must store cache_detail in seq_file->private if using next three functions */ 247 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); 248 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); 249 extern void cache_seq_stop_rcu(struct seq_file *file, void *p); 250 251 extern void qword_add(char **bpp, int *lp, char *str); 252 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 253 extern int qword_get(char **bpp, char *dest, int bufsize); 254 255 static inline int get_int(char **bpp, int *anint) 256 { 257 char buf[50]; 258 char *ep; 259 int rv; 260 int len = qword_get(bpp, buf, sizeof(buf)); 261 262 if (len < 0) 263 return -EINVAL; 264 if (len == 0) 265 return -ENOENT; 266 267 rv = simple_strtol(buf, &ep, 0); 268 if (*ep) 269 return -EINVAL; 270 271 *anint = rv; 272 return 0; 273 } 274 275 static inline int get_uint(char **bpp, unsigned int *anint) 276 { 277 char buf[50]; 278 int len = qword_get(bpp, buf, sizeof(buf)); 279 280 if (len < 0) 281 return -EINVAL; 282 if (len == 0) 283 return -ENOENT; 284 285 if (kstrtouint(buf, 0, anint)) 286 return -EINVAL; 287 288 return 0; 289 } 290 291 static inline int get_time(char **bpp, time64_t *time) 292 { 293 char buf[50]; 294 long long ll; 295 int len = qword_get(bpp, buf, sizeof(buf)); 296 297 if (len < 0) 298 return -EINVAL; 299 if (len == 0) 300 return -ENOENT; 301 302 if (kstrtoll(buf, 0, &ll)) 303 return -EINVAL; 304 305 *time = ll; 306 return 0; 307 } 308 309 static inline int get_expiry(char **bpp, time64_t *rvp) 310 { 311 int error; 312 struct timespec64 boot; 313 314 error = get_time(bpp, rvp); 315 if (error) 316 return error; 317 318 getboottime64(&boot); 319 (*rvp) -= boot.tv_sec; 320 return 0; 321 } 322 323 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 324