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