Initial import

1 files changed, 554 insertions, 0 deletions

diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
new file mode 100644
index 000000000..771484993
--- /dev/null
+++ b/include/linux/fscache-cache.h
@@ -0,0 +1,554 @@
+/* General filesystem caching backing cache interface
+ *
+ * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * 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.
+ *
+ * NOTE!!! See:
+ *
+ *	Documentation/filesystems/caching/backend-api.txt
+ *
+ * for a description of the cache backend interface declared here.
+ */
+
+#ifndef _LINUX_FSCACHE_CACHE_H
+#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;
+
+/*
+ * 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[0];	/* tag name */
+};
+
+/*
+ * cache definition
+ */
+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;
+	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+#define FSCACHE_CACHE_WITHDRAWN	1	/* cache has been withdrawn */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);
+
+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 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 *);
+
+/**
+ * fscache_operation_init - Do basic initialisation of an operation
+ * @op: The operation to initialise
+ * @release: The release function to assign
+ *
+ * Do basic initialisation of an operation.  The caller must still set flags,
+ * object and processor if needed.
+ */
+static inline void fscache_operation_init(struct fscache_operation *op,
+					fscache_operation_processor_t processor,
+					fscache_operation_release_t release)
+{
+	INIT_WORK(&op->work, fscache_op_work_func);
+	atomic_set(&op->usage, 1);
+	op->state = FSCACHE_OP_ST_INITIALISED;
+	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
+	op->processor = processor;
+	op->release = release;
+	INIT_LIST_HEAD(&op->pend_link);
+}
+
+/*
+ * data read operation
+ */
+struct fscache_retrieval {
+	struct fscache_operation op;
+	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 */
+	unsigned long		start_time;	/* time at which retrieval started */
+	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)
+{
+	atomic_sub(n_pages, &op->n_pages);
+	if (atomic_read(&op->n_pages) <= 0)
+		fscache_op_complete(&op->op, true);
+}
+
+/**
+ * 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 */
+};
+
+/*
+ * cache operations
+ */
+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);
+
+	/* 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 */
+	bool (*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);
+
+	/* 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);
+};
+
+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)
+
+/*
+ * 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
+ */
+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 */
+
+	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 */
+#ifdef CONFIG_FSCACHE_OBJECT_LIST
+	struct rb_node		objlist_link;	/* link in global object list */
+#endif
+	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_object_is_active(struct fscache_object *object)
+{
+	return fscache_object_is_available(object) &&
+		fscache_object_is_live(object) &&
+		!test_bit(FSCACHE_IOERROR, &object->cache->flags);
+}
+
+static inline bool fscache_object_is_dead(struct fscache_object *object)
+{
+	return fscache_object_is_dying(object) &&
+		test_bit(FSCACHE_IOERROR, &object->cache->flags);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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.
+ *
+ * See Documentation/filesystems/caching/backend-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_set_store_limit(struct fscache_object *object, loff_t i_size)
+{
+	object->store_limit_l = i_size;
+	object->store_limit = i_size >> PAGE_SHIFT;
+	if (i_size & ~PAGE_MASK)
+		object->store_limit++;
+}
+
+/**
+ * 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_atomic_t(&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);
+
+#endif /* _LINUX_FSCACHE_CACHE_H */