215 lines
7.1 KiB
C
215 lines
7.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
|
|
/* General filesystem caching backing cache interface
|
|
*
|
|
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
|
|
* Written by David Howells (dhowells@redhat.com)
|
|
*
|
|
* NOTE!!! See:
|
|
*
|
|
* Documentation/filesystems/caching/backend-api.rst
|
|
*
|
|
* for a description of the cache backend interface declared here.
|
|
*/
|
|
|
|
#ifndef _LINUX_FSCACHE_CACHE_H
|
|
#define _LINUX_FSCACHE_CACHE_H
|
|
|
|
#include <linux/fscache.h>
|
|
|
|
enum fscache_cache_trace;
|
|
enum fscache_cookie_trace;
|
|
enum fscache_access_trace;
|
|
enum fscache_volume_trace;
|
|
|
|
enum fscache_cache_state {
|
|
FSCACHE_CACHE_IS_NOT_PRESENT, /* No cache is present for this name */
|
|
FSCACHE_CACHE_IS_PREPARING, /* A cache is preparing to come live */
|
|
FSCACHE_CACHE_IS_ACTIVE, /* Attached cache is active and can be used */
|
|
FSCACHE_CACHE_GOT_IOERROR, /* Attached cache stopped on I/O error */
|
|
FSCACHE_CACHE_IS_WITHDRAWN, /* Attached cache is being withdrawn */
|
|
#define NR__FSCACHE_CACHE_STATE (FSCACHE_CACHE_IS_WITHDRAWN + 1)
|
|
};
|
|
|
|
/*
|
|
* Cache cookie.
|
|
*/
|
|
struct fscache_cache {
|
|
const struct fscache_cache_ops *ops;
|
|
struct list_head cache_link; /* Link in cache list */
|
|
void *cache_priv; /* Private cache data (or NULL) */
|
|
refcount_t ref;
|
|
atomic_t n_volumes; /* Number of active volumes; */
|
|
atomic_t n_accesses; /* Number of in-progress accesses on the cache */
|
|
atomic_t object_count; /* no. of live objects in this cache */
|
|
unsigned int debug_id;
|
|
enum fscache_cache_state state;
|
|
char *name;
|
|
};
|
|
|
|
/*
|
|
* cache operations
|
|
*/
|
|
struct fscache_cache_ops {
|
|
/* name of cache provider */
|
|
const char *name;
|
|
|
|
/* Acquire a volume */
|
|
void (*acquire_volume)(struct fscache_volume *volume);
|
|
|
|
/* Free the cache's data attached to a volume */
|
|
void (*free_volume)(struct fscache_volume *volume);
|
|
|
|
/* Look up a cookie in the cache */
|
|
bool (*lookup_cookie)(struct fscache_cookie *cookie);
|
|
|
|
/* Withdraw an object without any cookie access counts held */
|
|
void (*withdraw_cookie)(struct fscache_cookie *cookie);
|
|
|
|
/* Change the size of a data object */
|
|
void (*resize_cookie)(struct netfs_cache_resources *cres,
|
|
loff_t new_size);
|
|
|
|
/* Invalidate an object */
|
|
bool (*invalidate_cookie)(struct fscache_cookie *cookie);
|
|
|
|
/* Begin an operation for the netfs lib */
|
|
bool (*begin_operation)(struct netfs_cache_resources *cres,
|
|
enum fscache_want_state want_state);
|
|
|
|
/* Prepare to write to a live cache object */
|
|
void (*prepare_to_write)(struct fscache_cookie *cookie);
|
|
};
|
|
|
|
extern struct workqueue_struct *fscache_wq;
|
|
extern wait_queue_head_t fscache_clearance_waiters;
|
|
|
|
/*
|
|
* out-of-line cache backend functions
|
|
*/
|
|
extern struct rw_semaphore fscache_addremove_sem;
|
|
extern struct fscache_cache *fscache_acquire_cache(const char *name);
|
|
extern void fscache_relinquish_cache(struct fscache_cache *cache);
|
|
extern int fscache_add_cache(struct fscache_cache *cache,
|
|
const struct fscache_cache_ops *ops,
|
|
void *cache_priv);
|
|
extern void fscache_withdraw_cache(struct fscache_cache *cache);
|
|
extern void fscache_withdraw_volume(struct fscache_volume *volume);
|
|
extern void fscache_withdraw_cookie(struct fscache_cookie *cookie);
|
|
|
|
extern void fscache_io_error(struct fscache_cache *cache);
|
|
|
|
extern struct fscache_volume *
|
|
fscache_try_get_volume(struct fscache_volume *volume,
|
|
enum fscache_volume_trace where);
|
|
extern void fscache_put_volume(struct fscache_volume *volume,
|
|
enum fscache_volume_trace where);
|
|
extern void fscache_end_volume_access(struct fscache_volume *volume,
|
|
struct fscache_cookie *cookie,
|
|
enum fscache_access_trace why);
|
|
|
|
extern struct fscache_cookie *fscache_get_cookie(struct fscache_cookie *cookie,
|
|
enum fscache_cookie_trace where);
|
|
extern void fscache_put_cookie(struct fscache_cookie *cookie,
|
|
enum fscache_cookie_trace where);
|
|
extern void fscache_end_cookie_access(struct fscache_cookie *cookie,
|
|
enum fscache_access_trace why);
|
|
extern void fscache_cookie_lookup_negative(struct fscache_cookie *cookie);
|
|
extern void fscache_resume_after_invalidation(struct fscache_cookie *cookie);
|
|
extern void fscache_caching_failed(struct fscache_cookie *cookie);
|
|
extern bool fscache_wait_for_operation(struct netfs_cache_resources *cred,
|
|
enum fscache_want_state state);
|
|
|
|
/**
|
|
* fscache_cookie_state - Read the state of a cookie
|
|
* @cookie: The cookie to query
|
|
*
|
|
* Get the state of a cookie, imposing an ordering between the cookie contents
|
|
* and the state value. Paired with fscache_set_cookie_state().
|
|
*/
|
|
static inline
|
|
enum fscache_cookie_state fscache_cookie_state(struct fscache_cookie *cookie)
|
|
{
|
|
return smp_load_acquire(&cookie->state);
|
|
}
|
|
|
|
/**
|
|
* fscache_get_key - Get a pointer to the cookie key
|
|
* @cookie: The cookie to query
|
|
*
|
|
* Return a pointer to the where a cookie's key is stored.
|
|
*/
|
|
static inline void *fscache_get_key(struct fscache_cookie *cookie)
|
|
{
|
|
if (cookie->key_len <= sizeof(cookie->inline_key))
|
|
return cookie->inline_key;
|
|
else
|
|
return cookie->key;
|
|
}
|
|
|
|
static inline struct fscache_cookie *fscache_cres_cookie(struct netfs_cache_resources *cres)
|
|
{
|
|
return cres->cache_priv;
|
|
}
|
|
|
|
/**
|
|
* fscache_count_object - Tell fscache that an object has been added
|
|
* @cache: The cache to account to
|
|
*
|
|
* Tell fscache that an object has been added to the cache. This prevents the
|
|
* cache from tearing down the cache structure until the object is uncounted.
|
|
*/
|
|
static inline void fscache_count_object(struct fscache_cache *cache)
|
|
{
|
|
atomic_inc(&cache->object_count);
|
|
}
|
|
|
|
/**
|
|
* fscache_uncount_object - Tell fscache that an object has been removed
|
|
* @cache: The cache to account to
|
|
*
|
|
* Tell fscache that an object has been removed from the cache and will no
|
|
* longer be accessed. After this point, the cache cookie may be destroyed.
|
|
*/
|
|
static inline void fscache_uncount_object(struct fscache_cache *cache)
|
|
{
|
|
if (atomic_dec_and_test(&cache->object_count))
|
|
wake_up_all(&fscache_clearance_waiters);
|
|
}
|
|
|
|
/**
|
|
* fscache_wait_for_objects - Wait for all objects to be withdrawn
|
|
* @cache: The cache to query
|
|
*
|
|
* Wait for all extant objects in a cache to finish being withdrawn
|
|
* and go away.
|
|
*/
|
|
static inline void fscache_wait_for_objects(struct fscache_cache *cache)
|
|
{
|
|
wait_event(fscache_clearance_waiters,
|
|
atomic_read(&cache->object_count) == 0);
|
|
}
|
|
|
|
#ifdef CONFIG_FSCACHE_STATS
|
|
extern atomic_t fscache_n_read;
|
|
extern atomic_t fscache_n_write;
|
|
extern atomic_t fscache_n_no_write_space;
|
|
extern atomic_t fscache_n_no_create_space;
|
|
extern atomic_t fscache_n_culled;
|
|
extern atomic_t fscache_n_dio_misfit;
|
|
#define fscache_count_read() atomic_inc(&fscache_n_read)
|
|
#define fscache_count_write() atomic_inc(&fscache_n_write)
|
|
#define fscache_count_no_write_space() atomic_inc(&fscache_n_no_write_space)
|
|
#define fscache_count_no_create_space() atomic_inc(&fscache_n_no_create_space)
|
|
#define fscache_count_culled() atomic_inc(&fscache_n_culled)
|
|
#define fscache_count_dio_misfit() atomic_inc(&fscache_n_dio_misfit)
|
|
#else
|
|
#define fscache_count_read() do {} while(0)
|
|
#define fscache_count_write() do {} while(0)
|
|
#define fscache_count_no_write_space() do {} while(0)
|
|
#define fscache_count_no_create_space() do {} while(0)
|
|
#define fscache_count_culled() do {} while(0)
|
|
#define fscache_count_dio_misfit() do {} while(0)
|
|
#endif
|
|
|
|
#endif /* _LINUX_FSCACHE_CACHE_H */
|