/* * include/linux/sunrpc/cache.h * * Generic code for various authentication-related caches * used by sunrpc clients and servers. * * Copyright (C) 2002 Neil Brown * * Released under terms in GPL version 2. See COPYING. * */ #ifndef _LINUX_SUNRPC_CACHE_H_ #define _LINUX_SUNRPC_CACHE_H_ #include #include #include /* * Each cache requires: * - A 'struct cache_detail' which contains information specific to the cache * for common code to use. * - An item structure that must contain a "struct cache_head" * - A lookup function defined using DefineCacheLookup * - A 'put' function that can release a cache item. It will only * be called after cache_put has succeed, so there are guarantee * to be no references. * - A function to calculate a hash of an item's key. * * as well as assorted code fragments (e.g. compare keys) and numbers * (e.g. hash size, goal_age, etc). * * Each cache must be registered so that it can be cleaned regularly. * When the cache is unregistered, it is flushed completely. * * Entries have a ref count and a 'hashed' flag which counts the existance * in the hash table. * We only expire entries when refcount is zero. * Existance in the cache is counted the refcount. */ /* Every cache item has a common header that is used * for expiring and refreshing entries. * */ struct cache_head { struct cache_head * next; time_t expiry_time; /* After time time, don't use the data */ time_t last_refresh; /* If CACHE_PENDING, this is when upcall * was sent, else this is when update was received */ struct kref ref; unsigned long flags; }; #define CACHE_VALID 0 /* Entry contains valid data */ #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */ #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/ #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ struct cache_detail_procfs { struct proc_dir_entry *proc_ent; struct proc_dir_entry *flush_ent, *channel_ent, *content_ent; }; struct cache_detail { struct module * owner; int hash_size; struct cache_head ** hash_table; rwlock_t hash_lock; atomic_t inuse; /* active user-space update or lookup */ char *name; void (*cache_put)(struct kref *); int (*cache_upcall)(struct cache_detail *, struct cache_head *); int (*cache_parse)(struct cache_detail *, char *buf, int len); int (*cache_show)(struct seq_file *m, struct cache_detail *cd, struct cache_head *h); void (*warn_no_listener)(struct cache_detail *cd, int has_died); struct cache_head * (*alloc)(void); int (*match)(struct cache_head *orig, struct cache_head *new); void (*init)(struct cache_head *orig, struct cache_head *new); void (*update)(struct cache_head *orig, struct cache_head *new); /* fields below this comment are for internal use * and should not be touched by cache owners */ time_t flush_time; /* flush all cache items with last_refresh * earlier than this */ struct list_head others; time_t nextcheck; int entries; /* fields for communication over channel */ struct list_head queue; atomic_t readers; /* how many time is /chennel open */ time_t last_close; /* if no readers, when did last close */ time_t last_warn; /* when we last warned about no readers */ union { struct cache_detail_procfs procfs; } u; }; /* this must be embedded in any request structure that * identifies an object that will want a callback on * a cache fill */ struct cache_req { struct cache_deferred_req *(*defer)(struct cache_req *req); }; /* this must be embedded in a deferred_request that is being * delayed awaiting cache-fill */ struct cache_deferred_req { struct list_head hash; /* on hash chain */ struct list_head recent; /* on fifo */ struct cache_head *item; /* cache item we wait on */ void *owner; /* we might need to discard all defered requests * owned by someone */ void (*revisit)(struct cache_deferred_req *req, int too_many); }; extern struct cache_head * sunrpc_cache_lookup(struct cache_detail *detail, struct cache_head *key, int hash); extern struct cache_head * sunrpc_cache_update(struct cache_detail *detail, struct cache_head *new, struct cache_head *old, int hash); extern int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h, void (*cache_request)(struct cache_detail *, struct cache_head *, char **, int *)); extern void cache_clean_deferred(void *owner); static inline struct cache_head *cache_get(struct cache_head *h) { kref_get(&h->ref); return h; } static inline void cache_put(struct cache_head *h, struct cache_detail *cd) { if (atomic_read(&h->ref.refcount) <= 2 && h->expiry_time < cd->nextcheck) cd->nextcheck = h->expiry_time; kref_put(&h->ref, cd->cache_put); } static inline int cache_valid(struct cache_head *h) { /* If an item has been unhashed pending removal when * the refcount drops to 0, the expiry_time will be * set to 0. We don't want to consider such items * valid in this context even though CACHE_VALID is * set. */ return (h->expiry_time != 0 && test_bit(CACHE_VALID, &h->flags)); } extern int cache_check(struct cache_detail *detail, struct cache_head *h, struct cache_req *rqstp); extern void cache_flush(void); extern void cache_purge(struct cache_detail *detail); #define NEVER (0x7FFFFFFF) extern int cache_register(struct cache_detail *cd); extern void cache_unregister(struct cache_detail *cd); extern void qword_add(char **bpp, int *lp, char *str); extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); extern int qword_get(char **bpp, char *dest, int bufsize); static inline int get_int(char **bpp, int *anint) { char buf[50]; char *ep; int rv; int len = qword_get(bpp, buf, 50); if (len < 0) return -EINVAL; if (len ==0) return -ENOENT; rv = simple_strtol(buf, &ep, 0); if (*ep) return -EINVAL; *anint = rv; return 0; } static inline time_t get_expiry(char **bpp) { int rv; if (get_int(bpp, &rv)) return 0; if (rv < 0) return 0; return rv; } #endif /* _LINUX_SUNRPC_CACHE_H_ */