include/linux/sunrpc/cache.h

   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         time64_t        expiry_time;    /* After time time, don't use the data */
  49         time64_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         void                    (*flush)(void);
  91         int                     (*match)(struct cache_head *orig, struct cache_head *new);
  92         void                    (*init)(struct cache_head *orig, struct cache_head *new);
  93         void                    (*update)(struct cache_head *orig, struct cache_head *new);
  94
  95         /* fields below this comment are for internal use
  96          * and should not be touched by cache owners
  97          */
  98         time64_t                flush_time;             /* flush all cache items with
  99                                                          * last_refresh at or earlier
 100                                                          * than this.  last_refresh
 101                                                          * is never set at or earlier
 102                                                          * than this.
 103                                                          */
 104         struct list_head        others;
 105         time64_t                nextcheck;
 106         int                     entries;
 107
 108         /* fields for communication over channel */
 109         struct list_head        queue;
 110
 111         atomic_t                writers;                /* how many time is /channel open */
 112         time64_t                last_close;             /* if no writers, when did last close */
 113         time64_t                last_warn;              /* when we last warned about no writers */
 114
 115         union {
 116                 struct proc_dir_entry   *procfs;
 117                 struct dentry           *pipefs;
 118         };
 119         struct net              *net;
 120 };
 121
 122
 123 /* this must be embedded in any request structure that
 124  * identifies an object that will want a callback on
 125  * a cache fill
 126  */
 127 struct cache_req {
 128         struct cache_deferred_req *(*defer)(struct cache_req *req);
 129         int thread_wait;  /* How long (jiffies) we can block the
 130                            * current thread to wait for updates.
 131                            */
 132 };
 133 /* this must be embedded in a deferred_request that is being
 134  * delayed awaiting cache-fill
 135  */
 136 struct cache_deferred_req {
 137         struct hlist_node       hash;   /* on hash chain */
 138         struct list_head        recent; /* on fifo */
 139         struct cache_head       *item;  /* cache item we wait on */
 140         void                    *owner; /* we might need to discard all defered requests
 141                                          * owned by someone */
 142         void                    (*revisit)(struct cache_deferred_req *req,
 143                                            int too_many);
 144 };
 145
 146 /*
 147  * timestamps kept in the cache are expressed in seconds
 148  * since boot.  This is the best for measuring differences in
 149  * real time.
 150  * This reimplemnts ktime_get_boottime_seconds() in a slightly
 151  * faster but less accurate way. When we end up converting
 152  * back to wallclock (CLOCK_REALTIME), that error often
 153  * cancels out during the reverse operation.
 154  */
 155 static inline time64_t seconds_since_boot(void)
 156 {
 157         struct timespec64 boot;
 158         getboottime64(&boot);
 159         return ktime_get_real_seconds() - boot.tv_sec;
 160 }
 161
 162 static inline time64_t convert_to_wallclock(time64_t sinceboot)
 163 {
 164         struct timespec64 boot;
 165         getboottime64(&boot);
 166         return boot.tv_sec + sinceboot;
 167 }
 168
 169 extern const struct file_operations cache_file_operations_pipefs;
 170 extern const struct file_operations content_file_operations_pipefs;
 171 extern const struct file_operations cache_flush_operations_pipefs;
 172
 173 extern struct cache_head *
 174 sunrpc_cache_lookup_rcu(struct cache_detail *detail,
 175                         struct cache_head *key, int hash);
 176 extern struct cache_head *
 177 sunrpc_cache_update(struct cache_detail *detail,
 178                     struct cache_head *new, struct cache_head *old, int hash);
 179
 180 extern int
 181 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 182 extern int
 183 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
 184                                  struct cache_head *h);
 185
 186
 187 extern void cache_clean_deferred(void *owner);
 188
 189 static inline struct cache_head  *cache_get(struct cache_head *h)
 190 {
 191         kref_get(&h->ref);
 192         return h;
 193 }
 194
 195 static inline struct cache_head  *cache_get_rcu(struct cache_head *h)
 196 {
 197         if (kref_get_unless_zero(&h->ref))
 198                 return h;
 199         return NULL;
 200 }
 201
 202 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 203 {
 204         if (kref_read(&h->ref) <= 2 &&
 205             h->expiry_time < cd->nextcheck)
 206                 cd->nextcheck = h->expiry_time;
 207         kref_put(&h->ref, cd->cache_put);
 208 }
 209
 210 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 211 {
 212         if (h->expiry_time < seconds_since_boot())
 213                 return true;
 214         if (!test_bit(CACHE_VALID, &h->flags))
 215                 return false;
 216         return detail->flush_time >= h->last_refresh;
 217 }
 218
 219 extern int cache_check(struct cache_detail *detail,
 220                        struct cache_head *h, struct cache_req *rqstp);
 221 extern void cache_flush(void);
 222 extern void cache_purge(struct cache_detail *detail);
 223 #define NEVER (0x7FFFFFFF)
 224 extern void __init cache_initialize(void);
 225 extern int cache_register_net(struct cache_detail *cd, struct net *net);
 226 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 227
 228 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 229 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 230
 231 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 232 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 233 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 234                                         umode_t, struct cache_detail *);
 235 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 236 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 237
 238 /* Must store cache_detail in seq_file->private if using next three functions */
 239 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
 240 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
 241 extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
 242
 243 extern void qword_add(char **bpp, int *lp, char *str);
 244 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 245 extern int qword_get(char **bpp, char *dest, int bufsize);
 246
 247 static inline int get_int(char **bpp, int *anint)
 248 {
 249         char buf[50];
 250         char *ep;
 251         int rv;
 252         int len = qword_get(bpp, buf, sizeof(buf));
 253
 254         if (len < 0)
 255                 return -EINVAL;
 256         if (len == 0)
 257                 return -ENOENT;
 258
 259         rv = simple_strtol(buf, &ep, 0);
 260         if (*ep)
 261                 return -EINVAL;
 262
 263         *anint = rv;
 264         return 0;
 265 }
 266
 267 static inline int get_uint(char **bpp, unsigned int *anint)
 268 {
 269         char buf[50];
 270         int len = qword_get(bpp, buf, sizeof(buf));
 271
 272         if (len < 0)
 273                 return -EINVAL;
 274         if (len == 0)
 275                 return -ENOENT;
 276
 277         if (kstrtouint(buf, 0, anint))
 278                 return -EINVAL;
 279
 280         return 0;
 281 }
 282
 283 static inline int get_time(char **bpp, time64_t *time)
 284 {
 285         char buf[50];
 286         long long ll;
 287         int len = qword_get(bpp, buf, sizeof(buf));
 288
 289         if (len < 0)
 290                 return -EINVAL;
 291         if (len == 0)
 292                 return -ENOENT;
 293
 294         if (kstrtoll(buf, 0, &ll))
 295                 return -EINVAL;
 296
 297         *time = ll;
 298         return 0;
 299 }
 300
 301 static inline time64_t get_expiry(char **bpp)
 302 {
 303         time64_t rv;
 304         struct timespec64 boot;
 305
 306         if (get_time(bpp, &rv))
 307                 return 0;
 308         if (rv < 0)
 309                 return 0;
 310         getboottime64(&boot);
 311         return rv - boot.tv_sec;
 312 }
 313
 314 #endif /*  _LINUX_SUNRPC_CACHE_H_ */