include/linux/sunrpc/cache.h - pub/scm/linux/kernel/git/daveh/linux - Git at Google

 /*
  * 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_ */
	/*
	* 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_ */