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Diffstat (limited to 'include/linux/sunrpc/cache.h')
| -rw-r--r-- | include/linux/sunrpc/cache.h | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h new file mode 100644 index 000000000000..6864063d1b9f --- /dev/null +++ b/include/linux/sunrpc/cache.h @@ -0,0 +1,312 @@ +/* + * 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 { + 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_ */ |