linux-stable/include/linux/fscache.h
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

843 lines
29 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/* General filesystem caching interface
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* NOTE!!! See:
*
* Documentation/filesystems/caching/netfs-api.txt
*
* for a description of the network filesystem interface declared here.
*/
#ifndef _LINUX_FSCACHE_H
#define _LINUX_FSCACHE_H
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/list_bl.h>
#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
#define fscache_available() (1)
#define fscache_cookie_valid(cookie) (cookie)
#else
#define fscache_available() (0)
#define fscache_cookie_valid(cookie) (0)
#endif
/*
* overload PG_private_2 to give us PG_fscache - this is used to indicate that
* a page is currently backed by a local disk cache
*/
#define PageFsCache(page) PagePrivate2((page))
#define SetPageFsCache(page) SetPagePrivate2((page))
#define ClearPageFsCache(page) ClearPagePrivate2((page))
#define TestSetPageFsCache(page) TestSetPagePrivate2((page))
#define TestClearPageFsCache(page) TestClearPagePrivate2((page))
/* pattern used to fill dead space in an index entry */
#define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
struct pagevec;
struct fscache_cache_tag;
struct fscache_cookie;
struct fscache_netfs;
typedef void (*fscache_rw_complete_t)(struct page *page,
void *context,
int error);
/* result of index entry consultation */
enum fscache_checkaux {
FSCACHE_CHECKAUX_OKAY, /* entry okay as is */
FSCACHE_CHECKAUX_NEEDS_UPDATE, /* entry requires update */
FSCACHE_CHECKAUX_OBSOLETE, /* entry requires deletion */
};
/*
* fscache cookie definition
*/
struct fscache_cookie_def {
/* name of cookie type */
char name[16];
/* cookie type */
uint8_t type;
#define FSCACHE_COOKIE_TYPE_INDEX 0
#define FSCACHE_COOKIE_TYPE_DATAFILE 1
/* select the cache into which to insert an entry in this index
* - optional
* - should return a cache identifier or NULL to cause the cache to be
* inherited from the parent if possible or the first cache picked
* for a non-index file if not
*/
struct fscache_cache_tag *(*select_cache)(
const void *parent_netfs_data,
const void *cookie_netfs_data);
/* consult the netfs about the state of an object
* - this function can be absent if the index carries no state data
* - the netfs data from the cookie being used as the target is
* presented, as is the auxiliary data and the object size
*/
enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
const void *data,
uint16_t datalen,
loff_t object_size);
/* get an extra reference on a read context
* - this function can be absent if the completion function doesn't
* require a context
*/
void (*get_context)(void *cookie_netfs_data, void *context);
/* release an extra reference on a read context
* - this function can be absent if the completion function doesn't
* require a context
*/
void (*put_context)(void *cookie_netfs_data, void *context);
/* indicate page that now have cache metadata retained
* - this function should mark the specified page as now being cached
* - the page will have been marked with PG_fscache before this is
* called, so this is optional
*/
void (*mark_page_cached)(void *cookie_netfs_data,
struct address_space *mapping,
struct page *page);
};
/*
* fscache cached network filesystem type
* - name, version and ops must be filled in before registration
* - all other fields will be set during registration
*/
struct fscache_netfs {
uint32_t version; /* indexing version */
const char *name; /* filesystem name */
struct fscache_cookie *primary_index;
};
/*
* data file or index object cookie
* - a file will only appear in one cache
* - a request to cache a file may or may not be honoured, subject to
* constraints such as disk space
* - indices are created on disk just-in-time
*/
struct fscache_cookie {
atomic_t usage; /* number of users of this cookie */
atomic_t n_children; /* number of children of this cookie */
atomic_t n_active; /* number of active users of netfs ptrs */
spinlock_t lock;
spinlock_t stores_lock; /* lock on page store tree */
struct hlist_head backing_objects; /* object(s) backing this file/index */
const struct fscache_cookie_def *def; /* definition */
struct fscache_cookie *parent; /* parent of this entry */
struct hlist_bl_node hash_link; /* Link in hash table */
void *netfs_data; /* back pointer to netfs */
struct radix_tree_root stores; /* pages to be stored on this cookie */
#define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */
#define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */
unsigned long flags;
#define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
#define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */
#define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */
#define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */
#define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */
#define FSCACHE_COOKIE_ENABLED 5 /* T if cookie is enabled */
#define FSCACHE_COOKIE_ENABLEMENT_LOCK 6 /* T if cookie is being en/disabled */
#define FSCACHE_COOKIE_AUX_UPDATED 8 /* T if the auxiliary data was updated */
#define FSCACHE_COOKIE_ACQUIRED 9 /* T if cookie is in use */
#define FSCACHE_COOKIE_RELINQUISHING 10 /* T if cookie is being relinquished */
u8 type; /* Type of object */
u8 key_len; /* Length of index key */
u8 aux_len; /* Length of auxiliary data */
u32 key_hash; /* Hash of parent, type, key, len */
union {
void *key; /* Index key */
u8 inline_key[16]; /* - If the key is short enough */
};
union {
void *aux; /* Auxiliary data */
u8 inline_aux[8]; /* - If the aux data is short enough */
};
};
static inline bool fscache_cookie_enabled(struct fscache_cookie *cookie)
{
return test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
}
/*
* slow-path functions for when there is actually caching available, and the
* netfs does actually have a valid token
* - these are not to be called directly
* - these are undefined symbols when FS-Cache is not configured and the
* optimiser takes care of not using them
*/
extern int __fscache_register_netfs(struct fscache_netfs *);
extern void __fscache_unregister_netfs(struct fscache_netfs *);
extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *);
extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
extern struct fscache_cookie *__fscache_acquire_cookie(
struct fscache_cookie *,
const struct fscache_cookie_def *,
const void *, size_t,
const void *, size_t,
void *, loff_t, bool);
extern void __fscache_relinquish_cookie(struct fscache_cookie *, const void *, bool);
extern int __fscache_check_consistency(struct fscache_cookie *, const void *);
extern void __fscache_update_cookie(struct fscache_cookie *, const void *);
extern int __fscache_attr_changed(struct fscache_cookie *);
extern void __fscache_invalidate(struct fscache_cookie *);
extern void __fscache_wait_on_invalidate(struct fscache_cookie *);
extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
struct page *,
fscache_rw_complete_t,
void *,
gfp_t);
extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
struct address_space *,
struct list_head *,
unsigned *,
fscache_rw_complete_t,
void *,
gfp_t);
extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
extern int __fscache_write_page(struct fscache_cookie *, struct page *, loff_t, gfp_t);
extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
gfp_t);
extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
struct inode *);
extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
struct list_head *pages);
extern void __fscache_disable_cookie(struct fscache_cookie *, const void *, bool);
extern void __fscache_enable_cookie(struct fscache_cookie *, const void *, loff_t,
bool (*)(void *), void *);
/**
* fscache_register_netfs - Register a filesystem as desiring caching services
* @netfs: The description of the filesystem
*
* Register a filesystem as desiring caching services if they're available.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_register_netfs(struct fscache_netfs *netfs)
{
if (fscache_available())
return __fscache_register_netfs(netfs);
else
return 0;
}
/**
* fscache_unregister_netfs - Indicate that a filesystem no longer desires
* caching services
* @netfs: The description of the filesystem
*
* Indicate that a filesystem no longer desires caching services for the
* moment.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_unregister_netfs(struct fscache_netfs *netfs)
{
if (fscache_available())
__fscache_unregister_netfs(netfs);
}
/**
* fscache_lookup_cache_tag - Look up a cache tag
* @name: The name of the tag to search for
*
* Acquire a specific cache referral tag that can be used to select a specific
* cache in which to cache an index.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
{
if (fscache_available())
return __fscache_lookup_cache_tag(name);
else
return NULL;
}
/**
* fscache_release_cache_tag - Release a cache tag
* @tag: The tag to release
*
* Release a reference to a cache referral tag previously looked up.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_release_cache_tag(struct fscache_cache_tag *tag)
{
if (fscache_available())
__fscache_release_cache_tag(tag);
}
/**
* fscache_acquire_cookie - Acquire a cookie to represent a cache object
* @parent: The cookie that's to be the parent of this one
* @def: A description of the cache object, including callback operations
* @index_key: The index key for this cookie
* @index_key_len: Size of the index key
* @aux_data: The auxiliary data for the cookie (may be NULL)
* @aux_data_len: Size of the auxiliary data buffer
* @netfs_data: An arbitrary piece of data to be kept in the cookie to
* represent the cache object to the netfs
* @object_size: The initial size of object
* @enable: Whether or not to enable a data cookie immediately
*
* This function is used to inform FS-Cache about part of an index hierarchy
* that can be used to locate files. This is done by requesting a cookie for
* each index in the path to the file.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
struct fscache_cookie *fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
const void *index_key,
size_t index_key_len,
const void *aux_data,
size_t aux_data_len,
void *netfs_data,
loff_t object_size,
bool enable)
{
if (fscache_cookie_valid(parent) && fscache_cookie_enabled(parent))
return __fscache_acquire_cookie(parent, def,
index_key, index_key_len,
aux_data, aux_data_len,
netfs_data, object_size, enable);
else
return NULL;
}
/**
* fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
* it
* @cookie: The cookie being returned
* @aux_data: The updated auxiliary data for the cookie (may be NULL)
* @retire: True if the cache object the cookie represents is to be discarded
*
* This function returns a cookie to the cache, forcibly discarding the
* associated cache object if retire is set to true. The opportunity is
* provided to update the auxiliary data in the cache before the object is
* disconnected.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_relinquish_cookie(struct fscache_cookie *cookie,
const void *aux_data,
bool retire)
{
if (fscache_cookie_valid(cookie))
__fscache_relinquish_cookie(cookie, aux_data, retire);
}
/**
* fscache_check_consistency - Request validation of a cache's auxiliary data
* @cookie: The cookie representing the cache object
* @aux_data: The updated auxiliary data for the cookie (may be NULL)
*
* Request an consistency check from fscache, which passes the request to the
* backing cache. The auxiliary data on the cookie will be updated first if
* @aux_data is set.
*
* Returns 0 if consistent and -ESTALE if inconsistent. May also
* return -ENOMEM and -ERESTARTSYS.
*/
static inline
int fscache_check_consistency(struct fscache_cookie *cookie,
const void *aux_data)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_check_consistency(cookie, aux_data);
else
return 0;
}
/**
* fscache_update_cookie - Request that a cache object be updated
* @cookie: The cookie representing the cache object
* @aux_data: The updated auxiliary data for the cookie (may be NULL)
*
* Request an update of the index data for the cache object associated with the
* cookie. The auxiliary data on the cookie will be updated first if @aux_data
* is set.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
__fscache_update_cookie(cookie, aux_data);
}
/**
* fscache_pin_cookie - Pin a data-storage cache object in its cache
* @cookie: The cookie representing the cache object
*
* Permit data-storage cache objects to be pinned in the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_pin_cookie(struct fscache_cookie *cookie)
{
return -ENOBUFS;
}
/**
* fscache_pin_cookie - Unpin a data-storage cache object in its cache
* @cookie: The cookie representing the cache object
*
* Permit data-storage cache objects to be unpinned from the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_unpin_cookie(struct fscache_cookie *cookie)
{
}
/**
* fscache_attr_changed - Notify cache that an object's attributes changed
* @cookie: The cookie representing the cache object
*
* Send a notification to the cache indicating that an object's attributes have
* changed. This includes the data size. These attributes will be obtained
* through the get_attr() cookie definition op.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_attr_changed(struct fscache_cookie *cookie)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_attr_changed(cookie);
else
return -ENOBUFS;
}
/**
* fscache_invalidate - Notify cache that an object needs invalidation
* @cookie: The cookie representing the cache object
*
* Notify the cache that an object is needs to be invalidated and that it
* should abort any retrievals or stores it is doing on the cache. The object
* is then marked non-caching until such time as the invalidation is complete.
*
* This can be called with spinlocks held.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_invalidate(struct fscache_cookie *cookie)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
__fscache_invalidate(cookie);
}
/**
* fscache_wait_on_invalidate - Wait for invalidation to complete
* @cookie: The cookie representing the cache object
*
* Wait for the invalidation of an object to complete.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_wait_on_invalidate(struct fscache_cookie *cookie)
{
if (fscache_cookie_valid(cookie))
__fscache_wait_on_invalidate(cookie);
}
/**
* fscache_reserve_space - Reserve data space for a cached object
* @cookie: The cookie representing the cache object
* @i_size: The amount of space to be reserved
*
* Reserve an amount of space in the cache for the cache object attached to a
* cookie so that a write to that object within the space can always be
* honoured.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
{
return -ENOBUFS;
}
/**
* fscache_read_or_alloc_page - Read a page from the cache or allocate a block
* in which to store it
* @cookie: The cookie representing the cache object
* @page: The netfs page to fill if possible
* @end_io_func: The callback to invoke when and if the page is filled
* @context: An arbitrary piece of data to pass on to end_io_func()
* @gfp: The conditions under which memory allocation should be made
*
* Read a page from the cache, or if that's not possible make a potential
* one-block reservation in the cache into which the page may be stored once
* fetched from the server.
*
* If the page is not backed by the cache object, or if it there's some reason
* it can't be, -ENOBUFS will be returned and nothing more will be done for
* that page.
*
* Else, if that page is backed by the cache, a read will be initiated directly
* to the netfs's page and 0 will be returned by this function. The
* end_io_func() callback will be invoked when the operation terminates on a
* completion or failure. Note that the callback may be invoked before the
* return.
*
* Else, if the page is unbacked, -ENODATA is returned and a block may have
* been allocated in the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
struct page *page,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_read_or_alloc_page(cookie, page, end_io_func,
context, gfp);
else
return -ENOBUFS;
}
/**
* fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
* blocks in which to store them
* @cookie: The cookie representing the cache object
* @mapping: The netfs inode mapping to which the pages will be attached
* @pages: A list of potential netfs pages to be filled
* @nr_pages: Number of pages to be read and/or allocated
* @end_io_func: The callback to invoke when and if each page is filled
* @context: An arbitrary piece of data to pass on to end_io_func()
* @gfp: The conditions under which memory allocation should be made
*
* Read a set of pages from the cache, or if that's not possible, attempt to
* make a potential one-block reservation for each page in the cache into which
* that page may be stored once fetched from the server.
*
* If some pages are not backed by the cache object, or if it there's some
* reason they can't be, -ENOBUFS will be returned and nothing more will be
* done for that pages.
*
* Else, if some of the pages are backed by the cache, a read will be initiated
* directly to the netfs's page and 0 will be returned by this function. The
* end_io_func() callback will be invoked when the operation terminates on a
* completion or failure. Note that the callback may be invoked before the
* return.
*
* Else, if a page is unbacked, -ENODATA is returned and a block may have
* been allocated in the cache.
*
* Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
* regard to different pages, the return values are prioritised in that order.
* Any pages submitted for reading are removed from the pages list.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_read_or_alloc_pages(cookie, mapping, pages,
nr_pages, end_io_func,
context, gfp);
else
return -ENOBUFS;
}
/**
* fscache_alloc_page - Allocate a block in which to store a page
* @cookie: The cookie representing the cache object
* @page: The netfs page to allocate a page for
* @gfp: The conditions under which memory allocation should be made
*
* Request Allocation a block in the cache in which to store a netfs page
* without retrieving any contents from the cache.
*
* If the page is not backed by a file then -ENOBUFS will be returned and
* nothing more will be done, and no reservation will be made.
*
* Else, a block will be allocated if one wasn't already, and 0 will be
* returned
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_alloc_page(cookie, page, gfp);
else
return -ENOBUFS;
}
/**
* fscache_readpages_cancel - Cancel read/alloc on pages
* @cookie: The cookie representing the inode's cache object.
* @pages: The netfs pages that we canceled write on in readpages()
*
* Uncache/unreserve the pages reserved earlier in readpages() via
* fscache_readpages_or_alloc() and similar. In most successful caches in
* readpages() this doesn't do anything. In cases when the underlying netfs's
* readahead failed we need to clean up the pagelist (unmark and uncache).
*
* This function may sleep as it may have to clean up disk state.
*/
static inline
void fscache_readpages_cancel(struct fscache_cookie *cookie,
struct list_head *pages)
{
if (fscache_cookie_valid(cookie))
__fscache_readpages_cancel(cookie, pages);
}
/**
* fscache_write_page - Request storage of a page in the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page to store
* @object_size: Updated size of object
* @gfp: The conditions under which memory allocation should be made
*
* Request the contents of the netfs page be written into the cache. This
* request may be ignored if no cache block is currently allocated, in which
* case it will return -ENOBUFS.
*
* If a cache block was already allocated, a write will be initiated and 0 will
* be returned. The PG_fscache_write page bit is set immediately and will then
* be cleared at the completion of the write to indicate the success or failure
* of the operation. Note that the completion may happen before the return.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
loff_t object_size,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
return __fscache_write_page(cookie, page, object_size, gfp);
else
return -ENOBUFS;
}
/**
* fscache_uncache_page - Indicate that caching is no longer required on a page
* @cookie: The cookie representing the cache object
* @page: The netfs page that was being cached.
*
* Tell the cache that we no longer want a page to be cached and that it should
* remove any knowledge of the netfs page it may have.
*
* Note that this cannot cancel any outstanding I/O operations between this
* page and the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_uncache_page(struct fscache_cookie *cookie,
struct page *page)
{
if (fscache_cookie_valid(cookie))
__fscache_uncache_page(cookie, page);
}
/**
* fscache_check_page_write - Ask if a page is being writing to the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page that is being cached.
*
* Ask the cache if a page is being written to the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
bool fscache_check_page_write(struct fscache_cookie *cookie,
struct page *page)
{
if (fscache_cookie_valid(cookie))
return __fscache_check_page_write(cookie, page);
return false;
}
/**
* fscache_wait_on_page_write - Wait for a page to complete writing to the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page that is being cached.
*
* Ask the cache to wake us up when a page is no longer being written to the
* cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_wait_on_page_write(struct fscache_cookie *cookie,
struct page *page)
{
if (fscache_cookie_valid(cookie))
__fscache_wait_on_page_write(cookie, page);
}
/**
* fscache_maybe_release_page - Consider releasing a page, cancelling a store
* @cookie: The cookie representing the cache object
* @page: The netfs page that is being cached.
* @gfp: The gfp flags passed to releasepage()
*
* Consider releasing a page for the vmscan algorithm, on behalf of the netfs's
* releasepage() call. A storage request on the page may cancelled if it is
* not currently being processed.
*
* The function returns true if the page no longer has a storage request on it,
* and false if a storage request is left in place. If true is returned, the
* page will have been passed to fscache_uncache_page(). If false is returned
* the page cannot be freed yet.
*/
static inline
bool fscache_maybe_release_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie) && PageFsCache(page))
return __fscache_maybe_release_page(cookie, page, gfp);
return true;
}
/**
* fscache_uncache_all_inode_pages - Uncache all an inode's pages
* @cookie: The cookie representing the inode's cache object.
* @inode: The inode to uncache pages from.
*
* Uncache all the pages in an inode that are marked PG_fscache, assuming them
* to be associated with the given cookie.
*
* This function may sleep. It will wait for pages that are being written out
* and will wait whilst the PG_fscache mark is removed by the cache.
*/
static inline
void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
struct inode *inode)
{
if (fscache_cookie_valid(cookie))
__fscache_uncache_all_inode_pages(cookie, inode);
}
/**
* fscache_disable_cookie - Disable a cookie
* @cookie: The cookie representing the cache object
* @aux_data: The updated auxiliary data for the cookie (may be NULL)
* @invalidate: Invalidate the backing object
*
* Disable a cookie from accepting further alloc, read, write, invalidate,
* update or acquire operations. Outstanding operations can still be waited
* upon and pages can still be uncached and the cookie relinquished.
*
* This will not return until all outstanding operations have completed.
*
* If @invalidate is set, then the backing object will be invalidated and
* detached, otherwise it will just be detached.
*
* If @aux_data is set, then auxiliary data will be updated from that.
*/
static inline
void fscache_disable_cookie(struct fscache_cookie *cookie,
const void *aux_data,
bool invalidate)
{
if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
__fscache_disable_cookie(cookie, aux_data, invalidate);
}
/**
* fscache_enable_cookie - Reenable a cookie
* @cookie: The cookie representing the cache object
* @aux_data: The updated auxiliary data for the cookie (may be NULL)
* @object_size: Current size of object
* @can_enable: A function to permit enablement once lock is held
* @data: Data for can_enable()
*
* Reenable a previously disabled cookie, allowing it to accept further alloc,
* read, write, invalidate, update or acquire operations. An attempt will be
* made to immediately reattach the cookie to a backing object. If @aux_data
* is set, the auxiliary data attached to the cookie will be updated.
*
* The can_enable() function is called (if not NULL) once the enablement lock
* is held to rule on whether enablement is still permitted to go ahead.
*/
static inline
void fscache_enable_cookie(struct fscache_cookie *cookie,
const void *aux_data,
loff_t object_size,
bool (*can_enable)(void *data),
void *data)
{
if (fscache_cookie_valid(cookie) && !fscache_cookie_enabled(cookie))
__fscache_enable_cookie(cookie, aux_data, object_size,
can_enable, data);
}
#endif /* _LINUX_FSCACHE_H */