diff options
Diffstat (limited to 'include/linux/sunrpc/cache.h')
| -rw-r--r-- | include/linux/sunrpc/cache.h | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h new file mode 100644 index 000000000..ec5a555df --- /dev/null +++ b/include/linux/sunrpc/cache.h @@ -0,0 +1,316 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * 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> + */ + +#ifndef _LINUX_SUNRPC_CACHE_H_ +#define _LINUX_SUNRPC_CACHE_H_ + +#include <linux/kref.h> +#include <linux/slab.h> +#include <linux/atomic.h> +#include <linux/kstrtox.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 existence + * in the hash table. + * We only expire entries when refcount is zero. + * Existence 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 hlist_node cache_list; + time64_t expiry_time; /* After time expiry_time, don't use + * the data */ + time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was + * sent, else this is when update was + * received, though it is alway set to + * be *after* ->flush_time. + */ + 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_CLEANED 3 /* Entry has been cleaned from cache */ + +#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ + +struct cache_detail { + struct module * owner; + int hash_size; + struct hlist_head * hash_table; + spinlock_t hash_lock; + + char *name; + void (*cache_put)(struct kref *); + + int (*cache_upcall)(struct cache_detail *, + struct cache_head *); + + void (*cache_request)(struct cache_detail *cd, + struct cache_head *ch, + 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); + void (*warn_no_listener)(struct cache_detail *cd, + int has_died); + + struct cache_head * (*alloc)(void); + void (*flush)(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 + */ + time64_t flush_time; /* flush all cache items with + * last_refresh at or earlier + * than this. last_refresh + * is never set at or earlier + * than this. + */ + struct list_head others; + time64_t nextcheck; + int entries; + + /* fields for communication over channel */ + struct list_head queue; + + atomic_t writers; /* how many time is /channel open */ + time64_t last_close; /* if no writers, when did last close */ + time64_t last_warn; /* when we last warned about no writers */ + + union { + struct proc_dir_entry *procfs; + struct dentry *pipefs; + }; + struct net *net; +}; + +/* 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); + unsigned long thread_wait; /* How long (jiffies) we can block the + * current thread to wait for updates. + */ +}; + +/* this must be embedded in a deferred_request that is being + * delayed awaiting cache-fill + */ +struct cache_deferred_req { + struct hlist_node 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); +}; + +/* + * timestamps kept in the cache are expressed in seconds + * since boot. This is the best for measuring differences in + * real time. + * This reimplemnts ktime_get_boottime_seconds() in a slightly + * faster but less accurate way. When we end up converting + * back to wallclock (CLOCK_REALTIME), that error often + * cancels out during the reverse operation. + */ +static inline time64_t seconds_since_boot(void) +{ + struct timespec64 boot; + getboottime64(&boot); + return ktime_get_real_seconds() - boot.tv_sec; +} + +static inline time64_t convert_to_wallclock(time64_t sinceboot) +{ + struct timespec64 boot; + getboottime64(&boot); + return boot.tv_sec + sinceboot; +} + +extern const struct file_operations cache_file_operations_pipefs; +extern const struct file_operations content_file_operations_pipefs; +extern const struct file_operations cache_flush_operations_pipefs; + +extern struct cache_head * +sunrpc_cache_lookup_rcu(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); +extern int +sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail, + struct cache_head *h); + + +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 struct cache_head *cache_get_rcu(struct cache_head *h) +{ + if (kref_get_unless_zero(&h->ref)) + return h; + return NULL; +} + +static inline void cache_put(struct cache_head *h, struct cache_detail *cd) +{ + if (kref_read(&h->ref) <= 2 && + h->expiry_time < cd->nextcheck) + cd->nextcheck = h->expiry_time; + kref_put(&h->ref, cd->cache_put); +} + +static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) +{ + if (h->expiry_time < seconds_since_boot()) + return true; + if (!test_bit(CACHE_VALID, &h->flags)) + return false; + return detail->flush_time >= h->last_refresh; +} + +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 __init cache_initialize(void); +extern int cache_register_net(struct cache_detail *cd, struct net *net); +extern void cache_unregister_net(struct cache_detail *cd, struct net *net); + +extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net); +extern void cache_destroy_net(struct cache_detail *cd, struct net *net); + +extern void sunrpc_init_cache_detail(struct cache_detail *cd); +extern void sunrpc_destroy_cache_detail(struct cache_detail *cd); +extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, + umode_t, struct cache_detail *); +extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); +extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); + +/* Must store cache_detail in seq_file->private if using next three functions */ +extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); +extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); +extern void cache_seq_stop_rcu(struct seq_file *file, void *p); + +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, sizeof(buf)); + + 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 int get_uint(char **bpp, unsigned int *anint) +{ + char buf[50]; + int len = qword_get(bpp, buf, sizeof(buf)); + + if (len < 0) + return -EINVAL; + if (len == 0) + return -ENOENT; + + if (kstrtouint(buf, 0, anint)) + return -EINVAL; + + return 0; +} + +static inline int get_time(char **bpp, time64_t *time) +{ + char buf[50]; + long long ll; + int len = qword_get(bpp, buf, sizeof(buf)); + + if (len < 0) + return -EINVAL; + if (len == 0) + return -ENOENT; + + if (kstrtoll(buf, 0, &ll)) + return -EINVAL; + + *time = ll; + return 0; +} + +static inline time64_t get_expiry(char **bpp) +{ + time64_t rv; + struct timespec64 boot; + + if (get_time(bpp, &rv)) + return 0; + if (rv < 0) + return 0; + getboottime64(&boot); + return rv - boot.tv_sec; +} + +#endif /* _LINUX_SUNRPC_CACHE_H_ */ |