/* SPDX-License-Identifier: GPL-2.0-or-later */
/* General filesystem caching backing cache interface
*
- * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* NOTE!!! See:
#define _LINUX_FSCACHE_CACHE_H
#include <linux/fscache.h>
-#include <linux/sched.h>
-#include <linux/workqueue.h>
-#define NR_MAXCACHES BITS_PER_LONG
-
-struct fscache_cache;
-struct fscache_cache_ops;
-struct fscache_object;
-struct fscache_operation;
-
-enum fscache_obj_ref_trace {
- fscache_obj_get_add_to_deps,
- fscache_obj_get_queue,
- fscache_obj_put_alloc_fail,
- fscache_obj_put_attach_fail,
- fscache_obj_put_drop_obj,
- fscache_obj_put_enq_dep,
- fscache_obj_put_queue,
- fscache_obj_put_work,
- fscache_obj_ref__nr_traces
-};
-
-/*
- * cache tag definition
- */
-struct fscache_cache_tag {
- struct list_head link;
- struct fscache_cache *cache; /* cache referred to by this tag */
- unsigned long flags;
-#define FSCACHE_TAG_RESERVED 0 /* T if tag is reserved for a cache */
- atomic_t usage;
- char name[]; /* tag name */
+enum fscache_cache_trace;
+enum fscache_cookie_trace;
+enum fscache_access_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+ FSCACHE_CACHE_IS_WITHDRAWN, /* Attached cache is being withdrawn */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 definition
+ * Cache cookie.
*/
struct fscache_cache {
const struct fscache_cache_ops *ops;
- struct fscache_cache_tag *tag; /* tag representing this cache */
- struct kobject *kobj; /* system representation of this cache */
- struct list_head link; /* link in list of caches */
- size_t max_index_size; /* maximum size of index data */
- char identifier[36]; /* cache label */
-
- /* node management */
- struct work_struct op_gc; /* operation garbage collector */
- struct list_head object_list; /* list of data/index objects */
- struct list_head op_gc_list; /* list of ops to be deleted */
- spinlock_t object_list_lock;
- spinlock_t op_gc_list_lock;
+ 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 */
- struct fscache_object *fsdef; /* object for the fsdef index */
- unsigned long flags;
-#define FSCACHE_IOERROR 0 /* cache stopped on I/O error */
-#define FSCACHE_CACHE_WITHDRAWN 1 /* cache has been withdrawn */
-};
-
-extern wait_queue_head_t fscache_cache_cleared_wq;
-
-/*
- * operation to be applied to a cache object
- * - retrieval initiation operations are done in the context of the process
- * that issued them, and not in an async thread pool
- */
-typedef void (*fscache_operation_release_t)(struct fscache_operation *op);
-typedef void (*fscache_operation_processor_t)(struct fscache_operation *op);
-typedef void (*fscache_operation_cancel_t)(struct fscache_operation *op);
-
-enum fscache_operation_state {
- FSCACHE_OP_ST_BLANK, /* Op is not yet submitted */
- FSCACHE_OP_ST_INITIALISED, /* Op is initialised */
- FSCACHE_OP_ST_PENDING, /* Op is blocked from running */
- FSCACHE_OP_ST_IN_PROGRESS, /* Op is in progress */
- FSCACHE_OP_ST_COMPLETE, /* Op is complete */
- FSCACHE_OP_ST_CANCELLED, /* Op has been cancelled */
- FSCACHE_OP_ST_DEAD /* Op is now dead */
-};
-
-struct fscache_operation {
- struct work_struct work; /* record for async ops */
- struct list_head pend_link; /* link in object->pending_ops */
- struct fscache_object *object; /* object to be operated upon */
-
- unsigned long flags;
-#define FSCACHE_OP_TYPE 0x000f /* operation type */
-#define FSCACHE_OP_ASYNC 0x0001 /* - async op, processor may sleep for disk */
-#define FSCACHE_OP_MYTHREAD 0x0002 /* - processing is done be issuing thread, not pool */
-#define FSCACHE_OP_WAITING 4 /* cleared when op is woken */
-#define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */
-#define FSCACHE_OP_DEC_READ_CNT 6 /* decrement object->n_reads on destruction */
-#define FSCACHE_OP_UNUSE_COOKIE 7 /* call fscache_unuse_cookie() on completion */
-#define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */
-
- enum fscache_operation_state state;
- atomic_t usage;
- unsigned debug_id; /* debugging ID */
-
- /* operation processor callback
- * - can be NULL if FSCACHE_OP_WAITING is going to be used to perform
- * the op in a non-pool thread */
- fscache_operation_processor_t processor;
-
- /* Operation cancellation cleanup (optional) */
- fscache_operation_cancel_t cancel;
-
- /* operation releaser */
- fscache_operation_release_t release;
-};
-
-extern atomic_t fscache_op_debug_id;
-extern void fscache_op_work_func(struct work_struct *work);
-
-extern void fscache_enqueue_operation(struct fscache_operation *);
-extern void fscache_op_complete(struct fscache_operation *, bool);
-extern void fscache_put_operation(struct fscache_operation *);
-extern void fscache_operation_init(struct fscache_cookie *,
- struct fscache_operation *,
- fscache_operation_processor_t,
- fscache_operation_cancel_t,
- fscache_operation_release_t);
-
-/*
- * data read operation
- */
-struct fscache_retrieval {
- struct fscache_operation op;
- struct fscache_cookie *cookie; /* The netfs cookie */
- struct address_space *mapping; /* netfs pages */
- fscache_rw_complete_t end_io_func; /* function to call on I/O completion */
- void *context; /* netfs read context (pinned) */
- struct list_head to_do; /* list of things to be done by the backend */
- atomic_t n_pages; /* number of pages to be retrieved */
-};
-
-typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op,
- struct page *page,
- gfp_t gfp);
-
-typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op,
- struct list_head *pages,
- unsigned *nr_pages,
- gfp_t gfp);
-
-/**
- * fscache_get_retrieval - Get an extra reference on a retrieval operation
- * @op: The retrieval operation to get a reference on
- *
- * Get an extra reference on a retrieval operation.
- */
-static inline
-struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op)
-{
- atomic_inc(&op->op.usage);
- return op;
-}
-
-/**
- * fscache_enqueue_retrieval - Enqueue a retrieval operation for processing
- * @op: The retrieval operation affected
- *
- * Enqueue a retrieval operation for processing by the FS-Cache thread pool.
- */
-static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op)
-{
- fscache_enqueue_operation(&op->op);
-}
-
-/**
- * fscache_retrieval_complete - Record (partial) completion of a retrieval
- * @op: The retrieval operation affected
- * @n_pages: The number of pages to account for
- */
-static inline void fscache_retrieval_complete(struct fscache_retrieval *op,
- int n_pages)
-{
- if (atomic_sub_return_relaxed(n_pages, &op->n_pages) <= 0)
- fscache_op_complete(&op->op, false);
-}
-
-/**
- * fscache_put_retrieval - Drop a reference to a retrieval operation
- * @op: The retrieval operation affected
- *
- * Drop a reference to a retrieval operation.
- */
-static inline void fscache_put_retrieval(struct fscache_retrieval *op)
-{
- fscache_put_operation(&op->op);
-}
-
-/*
- * cached page storage work item
- * - used to do three things:
- * - batch writes to the cache
- * - do cache writes asynchronously
- * - defer writes until cache object lookup completion
- */
-struct fscache_storage {
- struct fscache_operation op;
- pgoff_t store_limit; /* don't write more than this */
+ unsigned int debug_id;
+ enum fscache_cache_state state;
+ char *name;
};
/*
struct fscache_cache_ops {
/* name of cache provider */
const char *name;
-
- /* allocate an object record for a cookie */
- struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
- struct fscache_cookie *cookie);
-
- /* look up the object for a cookie
- * - return -ETIMEDOUT to be requeued
- */
- int (*lookup_object)(struct fscache_object *object);
-
- /* finished looking up */
- void (*lookup_complete)(struct fscache_object *object);
-
- /* increment the usage count on this object (may fail if unmounting) */
- struct fscache_object *(*grab_object)(struct fscache_object *object,
- enum fscache_obj_ref_trace why);
-
- /* pin an object in the cache */
- int (*pin_object)(struct fscache_object *object);
-
- /* unpin an object in the cache */
- void (*unpin_object)(struct fscache_object *object);
-
- /* check the consistency between the backing cache and the FS-Cache
- * cookie */
- int (*check_consistency)(struct fscache_operation *op);
-
- /* store the updated auxiliary data on an object */
- void (*update_object)(struct fscache_object *object);
-
- /* Invalidate an object */
- void (*invalidate_object)(struct fscache_operation *op);
-
- /* discard the resources pinned by an object and effect retirement if
- * necessary */
- void (*drop_object)(struct fscache_object *object);
-
- /* dispose of a reference to an object */
- void (*put_object)(struct fscache_object *object,
- enum fscache_obj_ref_trace why);
-
- /* sync a cache */
- void (*sync_cache)(struct fscache_cache *cache);
-
- /* notification that the attributes of a non-index object (such as
- * i_size) have changed */
- int (*attr_changed)(struct fscache_object *object);
-
- /* reserve space for an object's data and associated metadata */
- int (*reserve_space)(struct fscache_object *object, loff_t i_size);
-
- /* request a backing block for a page be read or allocated in the
- * cache */
- fscache_page_retrieval_func_t read_or_alloc_page;
-
- /* request backing blocks for a list of pages be read or allocated in
- * the cache */
- fscache_pages_retrieval_func_t read_or_alloc_pages;
-
- /* request a backing block for a page be allocated in the cache so that
- * it can be written directly */
- fscache_page_retrieval_func_t allocate_page;
-
- /* request backing blocks for pages be allocated in the cache so that
- * they can be written directly */
- fscache_pages_retrieval_func_t allocate_pages;
-
- /* write a page to its backing block in the cache */
- int (*write_page)(struct fscache_storage *op, struct page *page);
-
- /* detach backing block from a page (optional)
- * - must release the cookie lock before returning
- * - may sleep
- */
- void (*uncache_page)(struct fscache_object *object,
- struct page *page);
-
- /* dissociate a cache from all the pages it was backing */
- void (*dissociate_pages)(struct fscache_cache *cache);
-
- /* Begin a read operation for the netfs lib */
- int (*begin_read_operation)(struct netfs_read_request *rreq,
- struct fscache_retrieval *op);
-};
-
-extern struct fscache_cookie fscache_fsdef_index;
-
-/*
- * Event list for fscache_object::{event_mask,events}
- */
-enum {
- FSCACHE_OBJECT_EV_NEW_CHILD, /* T if object has a new child */
- FSCACHE_OBJECT_EV_PARENT_READY, /* T if object's parent is ready */
- FSCACHE_OBJECT_EV_UPDATE, /* T if object should be updated */
- FSCACHE_OBJECT_EV_INVALIDATE, /* T if cache requested object invalidation */
- FSCACHE_OBJECT_EV_CLEARED, /* T if accessors all gone */
- FSCACHE_OBJECT_EV_ERROR, /* T if fatal error occurred during processing */
- FSCACHE_OBJECT_EV_KILL, /* T if netfs relinquished or cache withdrew object */
- NR_FSCACHE_OBJECT_EVENTS
};
-#define FSCACHE_OBJECT_EVENTS_MASK ((1UL << NR_FSCACHE_OBJECT_EVENTS) - 1)
+extern struct workqueue_struct *fscache_wq;
/*
- * States for object state machine.
- */
-struct fscache_transition {
- unsigned long events;
- const struct fscache_state *transit_to;
-};
-
-struct fscache_state {
- char name[24];
- char short_name[8];
- const struct fscache_state *(*work)(struct fscache_object *object,
- int event);
- const struct fscache_transition transitions[];
-};
-
-/*
- * on-disk cache file or index handle
+ * out-of-line cache backend functions
*/
-struct fscache_object {
- const struct fscache_state *state; /* Object state machine state */
- const struct fscache_transition *oob_table; /* OOB state transition table */
- int debug_id; /* debugging ID */
- int n_children; /* number of child objects */
- int n_ops; /* number of extant ops on object */
- int n_obj_ops; /* number of object ops outstanding on object */
- int n_in_progress; /* number of ops in progress */
- int n_exclusive; /* number of exclusive ops queued or in progress */
- atomic_t n_reads; /* number of read ops in progress */
- spinlock_t lock; /* state and operations lock */
-
- unsigned long lookup_jif; /* time at which lookup started */
- unsigned long oob_event_mask; /* OOB events this object is interested in */
- unsigned long event_mask; /* events this object is interested in */
- unsigned long events; /* events to be processed by this object
- * (order is important - using fls) */
-
- unsigned long flags;
-#define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */
-#define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */
-#define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */
-#define FSCACHE_OBJECT_IS_LIVE 3 /* T if object is not withdrawn or relinquished */
-#define FSCACHE_OBJECT_IS_LOOKED_UP 4 /* T if object has been looked up */
-#define FSCACHE_OBJECT_IS_AVAILABLE 5 /* T if object has become active */
-#define FSCACHE_OBJECT_RETIRED 6 /* T if object was retired on relinquishment */
-#define FSCACHE_OBJECT_KILLED_BY_CACHE 7 /* T if object was killed by the cache */
-#define FSCACHE_OBJECT_RUN_AFTER_DEAD 8 /* T if object has been dispatched after death */
-
- struct list_head cache_link; /* link in cache->object_list */
- struct hlist_node cookie_link; /* link in cookie->backing_objects */
- struct fscache_cache *cache; /* cache that supplied this object */
- struct fscache_cookie *cookie; /* netfs's file/index object */
- struct fscache_object *parent; /* parent object */
- struct work_struct work; /* attention scheduling record */
- struct list_head dependents; /* FIFO of dependent objects */
- struct list_head dep_link; /* link in parent's dependents list */
- struct list_head pending_ops; /* unstarted operations on this object */
- pgoff_t store_limit; /* current storage limit */
- loff_t store_limit_l; /* current storage limit */
-};
-
-extern void fscache_object_init(struct fscache_object *, struct fscache_cookie *,
- struct fscache_cache *);
-extern void fscache_object_destroy(struct fscache_object *);
-
-extern void fscache_object_lookup_negative(struct fscache_object *object);
-extern void fscache_obtained_object(struct fscache_object *object);
-
-static inline bool fscache_object_is_live(struct fscache_object *object)
-{
- return test_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
-}
-
-static inline bool fscache_object_is_dying(struct fscache_object *object)
-{
- return !fscache_object_is_live(object);
-}
-
-static inline bool fscache_object_is_available(struct fscache_object *object)
-{
- return test_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags);
-}
-
-static inline bool fscache_cache_is_broken(struct fscache_object *object)
-{
- return test_bit(FSCACHE_IOERROR, &object->cache->flags);
-}
-
-static inline bool fscache_object_is_active(struct fscache_object *object)
-{
- return fscache_object_is_available(object) &&
- fscache_object_is_live(object) &&
- !fscache_cache_is_broken(object);
-}
+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);
-/**
- * fscache_object_destroyed - Note destruction of an object in a cache
- * @cache: The cache from which the object came
- *
- * Note the destruction and deallocation of an object record in a cache.
- */
-static inline void fscache_object_destroyed(struct fscache_cache *cache)
-{
- if (atomic_dec_and_test(&cache->object_count))
- wake_up_all(&fscache_cache_cleared_wq);
-}
+extern void fscache_end_volume_access(struct fscache_volume *volume,
+ struct fscache_cookie *cookie,
+ enum fscache_access_trace why);
-/**
- * fscache_object_lookup_error - Note an object encountered an error
- * @object: The object on which the error was encountered
- *
- * Note that an object encountered a fatal error (usually an I/O error) and
- * that it should be withdrawn as soon as possible.
- */
-static inline void fscache_object_lookup_error(struct fscache_object *object)
-{
- set_bit(FSCACHE_OBJECT_EV_ERROR, &object->events);
-}
+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_set_cookie_state(struct fscache_cookie *cookie,
+ enum fscache_cookie_state state);
/**
- * fscache_set_store_limit - Set the maximum size to be stored in an object
- * @object: The object to set the maximum on
- * @i_size: The limit to set in bytes
- *
- * Set the maximum size an object is permitted to reach, implying the highest
- * byte that may be written. Intended to be called by the attr_changed() op.
+ * fscache_get_key - Get a pointer to the cookie key
+ * @cookie: The cookie to query
*
- * See Documentation/filesystems/caching/backend-api.rst for a complete
- * description.
+ * Return a pointer to the where a cookie's key is stored.
*/
-static inline
-void fscache_set_store_limit(struct fscache_object *object, loff_t i_size)
+static inline void *fscache_get_key(struct fscache_cookie *cookie)
{
- object->store_limit_l = i_size;
- object->store_limit = i_size >> PAGE_SHIFT;
- if (i_size & ~PAGE_MASK)
- object->store_limit++;
+ if (cookie->key_len <= sizeof(cookie->inline_key))
+ return cookie->inline_key;
+ else
+ return cookie->key;
}
-/**
- * fscache_end_io - End a retrieval operation on a page
- * @op: The FS-Cache operation covering the retrieval
- * @page: The page that was to be fetched
- * @error: The error code (0 if successful)
- *
- * Note the end of an operation to retrieve a page, as covered by a particular
- * operation record.
- */
-static inline void fscache_end_io(struct fscache_retrieval *op,
- struct page *page, int error)
-{
- op->end_io_func(page, op->context, error);
-}
-
-static inline void __fscache_use_cookie(struct fscache_cookie *cookie)
-{
- atomic_inc(&cookie->n_active);
-}
-
-/**
- * fscache_use_cookie - Request usage of cookie attached to an object
- * @object: Object description
- *
- * Request usage of the cookie attached to an object. NULL is returned if the
- * relinquishment had reduced the cookie usage count to 0.
- */
-static inline bool fscache_use_cookie(struct fscache_object *object)
-{
- struct fscache_cookie *cookie = object->cookie;
- return atomic_inc_not_zero(&cookie->n_active) != 0;
-}
-
-static inline bool __fscache_unuse_cookie(struct fscache_cookie *cookie)
-{
- return atomic_dec_and_test(&cookie->n_active);
-}
-
-static inline void __fscache_wake_unused_cookie(struct fscache_cookie *cookie)
-{
- wake_up_var(&cookie->n_active);
-}
-
-/**
- * fscache_unuse_cookie - Cease usage of cookie attached to an object
- * @object: Object description
- *
- * 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_object *object)
-{
- struct fscache_cookie *cookie = object->cookie;
- if (__fscache_unuse_cookie(cookie))
- __fscache_wake_unused_cookie(cookie);
-}
-
-/*
- * out-of-line cache backend functions
- */
-extern __printf(3, 4)
-void fscache_init_cache(struct fscache_cache *cache,
- const struct fscache_cache_ops *ops,
- const char *idfmt, ...);
-
-extern int fscache_add_cache(struct fscache_cache *cache,
- struct fscache_object *fsdef,
- const char *tagname);
-extern void fscache_withdraw_cache(struct fscache_cache *cache);
-
-extern void fscache_io_error(struct fscache_cache *cache);
-
-extern void fscache_mark_page_cached(struct fscache_retrieval *op,
- struct page *page);
-
-extern void fscache_mark_pages_cached(struct fscache_retrieval *op,
- struct pagevec *pagevec);
-
-extern bool fscache_object_sleep_till_congested(signed long *timeoutp);
-
-extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
- const void *data,
- uint16_t datalen,
- loff_t object_size);
-
-extern void fscache_object_retrying_stale(struct fscache_object *object);
-
-enum fscache_why_object_killed {
- FSCACHE_OBJECT_IS_STALE,
- FSCACHE_OBJECT_NO_SPACE,
- FSCACHE_OBJECT_WAS_RETIRED,
- FSCACHE_OBJECT_WAS_CULLED,
-};
-extern void fscache_object_mark_killed(struct fscache_object *object,
- enum fscache_why_object_killed why);
-
#endif /* _LINUX_FSCACHE_CACHE_H */
projects / linux-2.6-microblaze.git / blobdiff