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/* * include/linux/sunrpc/cache.h * * Generic code for various authentication-related caches * used by sunrpc clients and servers. * * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au> * * Released under terms in GPL version 2. See COPYING. * */ #ifndef _LINUX_SUNRPC_CACHE_H_ #define _LINUX_SUNRPC_CACHE_H_ #include <linux/slab.h> #include <asm/atomic.h> #include <linux/proc_fs.h> /* * 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 */ atomic_t refcnt; 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 { 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 cache_head *, struct cache_detail*); void (*cache_request)(struct cache_detail *cd, struct cache_head *h, char **bpp, int *blen); 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); /* 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; struct proc_dir_entry *proc_ent; struct proc_dir_entry *flush_ent, *channel_ent, *content_ent; 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 */ void (*warn_no_listener)(struct cache_detail *cd); }; /* 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 */ time_t recv_time; void *owner; /* we might need to discard all defered requests * owned by someone */ void (*revisit)(struct cache_deferred_req *req, int too_many); }; /* * just like a template in C++, this macro does cache lookup * for us. * The function is passed some sort of HANDLE from which a cache_detail * structure can be determined (via SETUP, DETAIL), a template * cache entry (type RTN*), and a "set" flag. Using the HASHFN and the * TEST, the function will try to find a matching cache entry in the cache. * If "set" == 0 : * If an entry is found, it is returned * If no entry is found, a new non-VALID entry is created. * If "set" == 1 and INPLACE == 0 : * If no entry is found a new one is inserted with data from "template" * If a non-CACHE_VALID entry is found, it is updated from template using UPDATE * If a CACHE_VALID entry is found, a new entry is swapped in with data * from "template" * If set == 1, and INPLACE == 1 : * As above, except that if a CACHE_VALID entry is found, we UPDATE in place * instead of swapping in a new entry. * * If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not * run but insteead CACHE_NEGATIVE is set in any new item. * In any case, the new entry is returned with a reference count. * * * RTN is a struct type for a cache entry * MEMBER is the member of the cache which is cache_head, which must be first * FNAME is the name for the function * ARGS are arguments to function and must contain RTN *item, int set. May * also contain something to be usedby SETUP or DETAIL to find cache_detail. * SETUP locates the cache detail and makes it available as... * DETAIL identifies the cache detail, possibly set up by SETUP * HASHFN returns a hash value of the cache entry "item" * TEST tests if "tmp" matches "item" * INIT copies key information from "item" to "new" * UPDATE copies content information from "item" to "tmp" * INPLACE is true if updates can happen inplace rather than allocating a new structure * * WARNING: any substantial changes to this must be reflected in * net/sunrpc/svcauth.c(auth_domain_lookup) * which is a similar routine that is open-coded. */ #define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \ RTN *FNAME ARGS \ { \ RTN *tmp, *new=NULL; \ struct cache_head **hp, **head; \ SETUP; \ head = &(DETAIL)->hash_table[HASHFN]; \ retry: \ if (set||new) write_lock(&(DETAIL)->hash_lock); \ else read_lock(&(DETAIL)->hash_lock); \ for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \ tmp = container_of(*hp, RTN, MEMBER); \ if (TEST) { /* found a match */ \ \ if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \ break; \ \ if (new) \ {INIT;} \ if (set) { \ if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\ { /* need to swap in new */ \ RTN *t2; \ \ new->MEMBER.next = tmp->MEMBER.next; \ *hp = &new->MEMBER; \ tmp->MEMBER.next = NULL; \ t2 = tmp; tmp = new; new = t2; \ } \ if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \ set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ else { \ UPDATE; \ clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ } \ } \ cache_get(&tmp->MEMBER); \ if (set||new) write_unlock(&(DETAIL)->hash_lock); \ else read_unlock(&(DETAIL)->hash_lock); \ if (set) \ cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \ if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \ if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \ return tmp; \ } \ } \ /* Didn't find anything */ \ if (new) { \ INIT; \ new->MEMBER.next = *head; \ *head = &new->MEMBER; \ (DETAIL)->entries ++; \ cache_get(&new->MEMBER); \ if (set) { \ tmp = new; \ if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \ set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ else {UPDATE;} \ } \ } \ if (set||new) write_unlock(&(DETAIL)->hash_lock); \ else read_unlock(&(DETAIL)->hash_lock); \ if (new && set) \ cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \ if (new) \ return new; \ new = kmalloc(sizeof(*new), GFP_KERNEL); \ if (new) { \ cache_init(&new->MEMBER); \ goto retry; \ } \ return NULL; \ } #define DefineSimpleCacheLookup(STRUCT,INPLACE) \ DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT *item, int set), /*no setup */, \ & STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\ STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE) #define cache_for_each(pos, detail, index, member) \ for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \ ({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \ ) \ for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \ &pos->member; \ pos = container_of(pos->member.next, typeof(*pos), member)) extern void cache_clean_deferred(void *owner); static inline struct cache_head *cache_get(struct cache_head *h) { atomic_inc(&h->refcnt); return h; } static inline int cache_put(struct cache_head *h, struct cache_detail *cd) { if (atomic_read(&h->refcnt) <= 2 && h->expiry_time < cd->nextcheck) cd->nextcheck = h->expiry_time; return atomic_dec_and_test(&h->refcnt); } extern void cache_init(struct cache_head *h); extern void cache_fresh(struct cache_detail *detail, struct cache_head *head, time_t expiry); 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 void cache_register(struct cache_detail *cd); extern int 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_ */