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![NeilBrown](/assets/img/avatar_default.png)
When a sequence of numbers are needed for internal-use only, an enum is typically best. The sequence will inevitably need to be changed one day, and having an enum means the developer doesn't need to think about renumbering after insertion or deletion. Such patches will be easier to review. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
321 lines
9 KiB
C
321 lines
9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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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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#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/kstrtox.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 hlist_node cache_list;
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time64_t expiry_time; /* After time expiry_time, don't use
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* the data */
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time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was
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* sent, else this is when update was
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* received, though it is alway set to
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* be *after* ->flush_time.
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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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/* cache_head.flags */
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enum {
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CACHE_VALID, /* Entry contains valid data */
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CACHE_NEGATIVE, /* Negative entry - there is no match for the key */
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CACHE_PENDING, /* An upcall has been sent but no reply received yet*/
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CACHE_CLEANED, /* Entry has been cleaned from cache */
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};
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#define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
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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 hlist_head * hash_table;
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spinlock_t hash_lock;
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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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void (*cache_request)(struct cache_detail *cd,
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struct cache_head *ch,
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char **bpp, int *blen);
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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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void (*flush)(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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time64_t flush_time; /* flush all cache items with
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* last_refresh at or earlier
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* than this. last_refresh
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* is never set at or earlier
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* than this.
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*/
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struct list_head others;
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time64_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 writers; /* how many time is /channel open */
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time64_t last_close; /* if no writers, when did last close */
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time64_t last_warn; /* when we last warned about no writers */
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union {
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struct proc_dir_entry *procfs;
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struct dentry *pipefs;
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};
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struct net *net;
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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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unsigned long 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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/*
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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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* This reimplemnts ktime_get_boottime_seconds() in a slightly
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* faster but less accurate way. When we end up converting
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* back to wallclock (CLOCK_REALTIME), that error often
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* cancels out during the reverse operation.
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*/
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static inline time64_t seconds_since_boot(void)
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{
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struct timespec64 boot;
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getboottime64(&boot);
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return ktime_get_real_seconds() - boot.tv_sec;
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}
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static inline time64_t convert_to_wallclock(time64_t sinceboot)
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{
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struct timespec64 boot;
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getboottime64(&boot);
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return boot.tv_sec + sinceboot;
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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_rcu(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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extern int
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sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
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struct cache_head *h);
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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 struct cache_head *cache_get_rcu(struct cache_head *h)
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{
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if (kref_get_unless_zero(&h->ref))
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return h;
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return NULL;
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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 (kref_read(&h->ref) <= 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 bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
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{
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if (h->expiry_time < seconds_since_boot())
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return true;
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if (!test_bit(CACHE_VALID, &h->flags))
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return false;
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return detail->flush_time >= h->last_refresh;
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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_net(struct cache_detail *cd, struct net *net);
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extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
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extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
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extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
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extern void sunrpc_init_cache_detail(struct cache_detail *cd);
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extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
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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 sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
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/* Must store cache_detail in seq_file->private if using next three functions */
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extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
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extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
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extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
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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, sizeof(buf));
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if (len < 0)
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return -EINVAL;
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if (len == 0)
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return -ENOENT;
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rv = simple_strtol(buf, &ep, 0);
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if (*ep)
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return -EINVAL;
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*anint = rv;
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return 0;
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}
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static inline int get_uint(char **bpp, unsigned int *anint)
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{
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char buf[50];
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int len = qword_get(bpp, buf, sizeof(buf));
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if (len < 0)
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return -EINVAL;
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if (len == 0)
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return -ENOENT;
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if (kstrtouint(buf, 0, anint))
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return -EINVAL;
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return 0;
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}
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static inline int get_time(char **bpp, time64_t *time)
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{
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char buf[50];
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long long ll;
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int len = qword_get(bpp, buf, sizeof(buf));
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if (len < 0)
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return -EINVAL;
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if (len == 0)
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return -ENOENT;
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if (kstrtoll(buf, 0, &ll))
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return -EINVAL;
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*time = ll;
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return 0;
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}
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static inline int get_expiry(char **bpp, time64_t *rvp)
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{
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int error;
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struct timespec64 boot;
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error = get_time(bpp, rvp);
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if (error)
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return error;
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getboottime64(&boot);
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(*rvp) -= boot.tv_sec;
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return 0;
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}
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#endif /* _LINUX_SUNRPC_CACHE_H_ */
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