/* SPDX-License-Identifier: GPL-2.0-or-later */ /* General filesystem caching interface * * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. * Written by David Howells ([email protected]) * * NOTE!!! See: * * Documentation/filesystems/caching/netfs-api.rst * * for a description of the network filesystem interface declared here. */ #ifndef _LINUX_FSCACHE_H #define _LINUX_FSCACHE_H #include <linux/fs.h> #include <linux/netfs.h> #include <linux/writeback.h> #if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE) #define __fscache_available … #define fscache_available() … #define fscache_volume_valid(volume) … #define fscache_cookie_valid(cookie) … #define fscache_resources_valid(cres) … #define fscache_cookie_enabled(cookie) … #else #define __fscache_available … #define fscache_available … #define fscache_volume_valid … #define fscache_cookie_valid … #define fscache_resources_valid … #define fscache_cookie_enabled … #endif struct fscache_cookie; #define FSCACHE_ADV_SINGLE_CHUNK … #define FSCACHE_ADV_WRITE_CACHE … #define FSCACHE_ADV_WRITE_NOCACHE … #define FSCACHE_ADV_WANT_CACHE_SIZE … #define FSCACHE_INVAL_DIO_WRITE … enum fscache_want_state { … }; /* * Data object state. */ enum fscache_cookie_state { … } __attribute__((mode …)); /* * Volume representation cookie. */ struct fscache_volume { … }; /* * Data file representation 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 { … }; /* * 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 struct fscache_volume *__fscache_acquire_volume(const char *, const char *, const void *, size_t); extern void __fscache_relinquish_volume(struct fscache_volume *, const void *, bool); extern struct fscache_cookie *__fscache_acquire_cookie( struct fscache_volume *, u8, const void *, size_t, const void *, size_t, loff_t); extern void __fscache_use_cookie(struct fscache_cookie *, bool); extern void __fscache_unuse_cookie(struct fscache_cookie *, const void *, const loff_t *); extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool); extern void __fscache_resize_cookie(struct fscache_cookie *, loff_t); extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t, unsigned int); extern int __fscache_begin_read_operation(struct netfs_cache_resources *, struct fscache_cookie *); extern int __fscache_begin_write_operation(struct netfs_cache_resources *, struct fscache_cookie *); void __fscache_write_to_cache(struct fscache_cookie *cookie, struct address_space *mapping, loff_t start, size_t len, loff_t i_size, netfs_io_terminated_t term_func, void *term_func_priv, bool using_pgpriv2, bool cond); extern void __fscache_clear_page_bits(struct address_space *, loff_t, size_t); /** * fscache_acquire_volume - Register a volume as desiring caching services * @volume_key: An identification string for the volume * @cache_name: The name of the cache to use (or NULL for the default) * @coherency_data: Piece of arbitrary coherency data to check (or NULL) * @coherency_len: The size of the coherency data * * Register a volume as desiring caching services if they're available. The * caller must provide an identifier for the volume and may also indicate which * cache it should be in. If a preexisting volume entry is found in the cache, * the coherency data must match otherwise the entry will be invalidated. * * Returns a cookie pointer on success, -ENOMEM if out of memory or -EBUSY if a * cache volume of that name is already acquired. Note that "NULL" is a valid * cookie pointer and can be returned if caching is refused. */ static inline struct fscache_volume *fscache_acquire_volume(const char *volume_key, const char *cache_name, const void *coherency_data, size_t coherency_len) { … } /** * fscache_relinquish_volume - Cease caching a volume * @volume: The volume cookie * @coherency_data: Piece of arbitrary coherency data to set (or NULL) * @invalidate: True if the volume should be invalidated * * Indicate that a filesystem no longer desires caching services for a volume. * The caller must have relinquished all file cookies prior to calling this. * The stored coherency data is updated. */ static inline void fscache_relinquish_volume(struct fscache_volume *volume, const void *coherency_data, bool invalidate) { … } /** * fscache_acquire_cookie - Acquire a cookie to represent a cache object * @volume: The volume in which to locate/create this cookie * @advice: Advice flags (FSCACHE_COOKIE_ADV_*) * @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 * @object_size: The initial size of object * * Acquire a cookie to represent a data file within the given cache volume. * * See Documentation/filesystems/caching/netfs-api.rst for a complete * description. */ static inline struct fscache_cookie *fscache_acquire_cookie(struct fscache_volume *volume, u8 advice, const void *index_key, size_t index_key_len, const void *aux_data, size_t aux_data_len, loff_t object_size) { … } /** * fscache_use_cookie - Request usage of cookie attached to an object * @cookie: The cookie representing the cache object * @will_modify: If cache is expected to be modified locally * * Request usage of the cookie attached to an object. The caller should tell * the cache if the object's contents are about to be modified locally and then * the cache can apply the policy that has been set to handle this case. */ static inline void fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify) { … } /** * fscache_unuse_cookie - Cease usage of cookie attached to an object * @cookie: The cookie representing the cache object * @aux_data: Updated auxiliary data (or NULL) * @object_size: Revised size of the object (or NULL) * * Cease usage of the cookie attached to an object. When the users count * reaches zero then the cookie relinquishment will be permitted to proceed. */ static inline void fscache_unuse_cookie(struct fscache_cookie *cookie, const void *aux_data, const loff_t *object_size) { … } /** * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding * it * @cookie: The cookie being returned * @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. * * See Documentation/filesystems/caching/netfs-api.rst for a complete * description. */ static inline void fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire) { … } /* * Find the auxiliary data on a cookie. */ static inline void *fscache_get_aux(struct fscache_cookie *cookie) { … } /* * Update the auxiliary data on a cookie. */ static inline void fscache_update_aux(struct fscache_cookie *cookie, const void *aux_data, const loff_t *object_size) { … } #ifdef CONFIG_FSCACHE_STATS extern atomic_t fscache_n_updates; #endif static inline void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data, const loff_t *object_size) { … } /** * 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) * @object_size: The current size of the object (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 and the object size will be updated and the object possibly trimmed * if @object_size is set. * * See Documentation/filesystems/caching/netfs-api.rst for a complete * description. */ static inline void fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data, const loff_t *object_size) { … } /** * fscache_resize_cookie - Request that a cache object be resized * @cookie: The cookie representing the cache object * @new_size: The new size of the object (may be NULL) * * Request that the size of an object be changed. * * See Documentation/filesystems/caching/netfs-api.rst for a complete * description. */ static inline void fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size) { … } /** * fscache_invalidate - Notify cache that an object needs invalidation * @cookie: The cookie representing the cache object * @aux_data: The updated auxiliary data for the cookie (may be NULL) * @size: The revised size of the object. * @flags: Invalidation flags (FSCACHE_INVAL_*) * * 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. This * increments inval_counter on the cookie which can be used by the caller to * reconsider I/O requests as they complete. * * If @flags has FSCACHE_INVAL_DIO_WRITE set, this indicates that this is due * to a direct I/O write and will cause caching to be disabled on this cookie * until it is completely unused. * * See Documentation/filesystems/caching/netfs-api.rst for a complete * description. */ static inline void fscache_invalidate(struct fscache_cookie *cookie, const void *aux_data, loff_t size, unsigned int flags) { … } /** * fscache_operation_valid - Return true if operations resources are usable * @cres: The resources to check. * * Returns a pointer to the operations table if usable or NULL if not. */ static inline const struct netfs_cache_ops *fscache_operation_valid(const struct netfs_cache_resources *cres) { … } /** * fscache_begin_read_operation - Begin a read operation for the netfs lib * @cres: The cache resources for the read being performed * @cookie: The cookie representing the cache object * * Begin a read operation on behalf of the netfs helper library. @cres * indicates the cache resources to which the operation state should be * attached; @cookie indicates the cache object that will be accessed. * * @cres->inval_counter is set from @cookie->inval_counter for comparison at * the end of the operation. This allows invalidation during the operation to * be detected by the caller. * * Returns: * * 0 - Success * * -ENOBUFS - No caching available * * Other error code from the cache, such as -ENOMEM. */ static inline int fscache_begin_read_operation(struct netfs_cache_resources *cres, struct fscache_cookie *cookie) { … } /** * fscache_end_operation - End the read operation for the netfs lib * @cres: The cache resources for the read operation * * Clean up the resources at the end of the read request. */ static inline void fscache_end_operation(struct netfs_cache_resources *cres) { … } /** * fscache_read - Start a read from the cache. * @cres: The cache resources to use * @start_pos: The beginning file offset in the cache file * @iter: The buffer to fill - and also the length * @read_hole: How to handle a hole in the data. * @term_func: The function to call upon completion * @term_func_priv: The private data for @term_func * * Start a read from the cache. @cres indicates the cache object to read from * and must be obtained by a call to fscache_begin_operation() beforehand. * * The data is read into the iterator, @iter, and that also indicates the size * of the operation. @start_pos is the start position in the file, though if * @seek_data is set appropriately, the cache can use SEEK_DATA to find the * next piece of data, writing zeros for the hole into the iterator. * * Upon termination of the operation, @term_func will be called and supplied * with @term_func_priv plus the amount of data written, if successful, or the * error code otherwise. * * @read_hole indicates how a partially populated region in the cache should be * handled. It can be one of a number of settings: * * NETFS_READ_HOLE_IGNORE - Just try to read (may return a short read). * * NETFS_READ_HOLE_CLEAR - Seek for data, clearing the part of the buffer * skipped over, then do as for IGNORE. * * NETFS_READ_HOLE_FAIL - Give ENODATA if we encounter a hole. */ static inline int fscache_read(struct netfs_cache_resources *cres, loff_t start_pos, struct iov_iter *iter, enum netfs_read_from_hole read_hole, netfs_io_terminated_t term_func, void *term_func_priv) { … } /** * fscache_begin_write_operation - Begin a write operation for the netfs lib * @cres: The cache resources for the write being performed * @cookie: The cookie representing the cache object * * Begin a write operation on behalf of the netfs helper library. @cres * indicates the cache resources to which the operation state should be * attached; @cookie indicates the cache object that will be accessed. * * @cres->inval_counter is set from @cookie->inval_counter for comparison at * the end of the operation. This allows invalidation during the operation to * be detected by the caller. * * Returns: * * 0 - Success * * -ENOBUFS - No caching available * * Other error code from the cache, such as -ENOMEM. */ static inline int fscache_begin_write_operation(struct netfs_cache_resources *cres, struct fscache_cookie *cookie) { … } /** * fscache_write - Start a write to the cache. * @cres: The cache resources to use * @start_pos: The beginning file offset in the cache file * @iter: The data to write - and also the length * @term_func: The function to call upon completion * @term_func_priv: The private data for @term_func * * Start a write to the cache. @cres indicates the cache object to write to and * must be obtained by a call to fscache_begin_operation() beforehand. * * The data to be written is obtained from the iterator, @iter, and that also * indicates the size of the operation. @start_pos is the start position in * the file. * * Upon termination of the operation, @term_func will be called and supplied * with @term_func_priv plus the amount of data written, if successful, or the * error code otherwise. */ static inline int fscache_write(struct netfs_cache_resources *cres, loff_t start_pos, struct iov_iter *iter, netfs_io_terminated_t term_func, void *term_func_priv) { … } /** * fscache_clear_page_bits - Clear the PG_fscache bits from a set of pages * @mapping: The netfs inode to use as the source * @start: The start position in @mapping * @len: The amount of data to unlock * @caching: If PG_fscache has been set * * Clear the PG_fscache flag from a sequence of pages and wake up anyone who's * waiting. */ static inline void fscache_clear_page_bits(struct address_space *mapping, loff_t start, size_t len, bool caching) { … } /** * fscache_write_to_cache - Save a write to the cache and clear PG_fscache * @cookie: The cookie representing the cache object * @mapping: The netfs inode to use as the source * @start: The start position in @mapping * @len: The amount of data to write back * @i_size: The new size of the inode * @term_func: The function to call upon completion * @term_func_priv: The private data for @term_func * @using_pgpriv2: If we're using PG_private_2 to mark in-progress write * @caching: If we actually want to do the caching * * Helper function for a netfs to write dirty data from an inode into the cache * object that's backing it. * * @start and @len describe the range of the data. This does not need to be * page-aligned, but to satisfy DIO requirements, the cache may expand it up to * the page boundaries on either end. All the pages covering the range must be * marked with PG_fscache. * * If given, @term_func will be called upon completion and supplied with * @term_func_priv. Note that if @using_pgpriv2 is set, the PG_private_2 flags * will have been cleared by this point, so the netfs must retain its own pin * on the mapping. */ static inline void fscache_write_to_cache(struct fscache_cookie *cookie, struct address_space *mapping, loff_t start, size_t len, loff_t i_size, netfs_io_terminated_t term_func, void *term_func_priv, bool using_pgpriv2, bool caching) { … } /** * fscache_note_page_release - Note that a netfs page got released * @cookie: The cookie corresponding to the file * * Note that a page that has been copied to the cache has been released. This * means that future reads will need to look in the cache to see if it's there. */ static inline void fscache_note_page_release(struct fscache_cookie *cookie) { … } #endif /* _LINUX_FSCACHE_H */
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