8 files changed, 1293 insertions, 6 deletions

diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
new file mode 100644
index 000000000000..84d3532dd3ea
--- /dev/null
+++ b/include/linux/fscache-cache.h
@@ -0,0 +1,505 @@
+/* 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/slow-work.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);
+
+struct fscache_operation {
+        union {
+                struct work_struct fast_work;   /* record for fast ops */
+                struct slow_work slow_work;     /* record for (very) slow 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_FAST         0x0001  /* - fast op, processor may not sleep for disk */
+#define FSCACHE_OP_SLOW         0x0002  /* - (very) slow op, processor may sleep for disk */
+#define FSCACHE_OP_MYTHREAD     0x0003  /* - 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_DEAD         6       /* op is now dead */
+
+        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 const struct slow_work_ops fscache_op_slow_work_ops;
+
+extern void fscache_enqueue_operation(struct fscache_operation *);
+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, either fast_work or slow_work if necessary, and processor if needed.
+ */
+static inline void fscache_operation_init(struct fscache_operation *op,
+                                          fscache_operation_release_t release)
+{
+        atomic_set(&op->usage, 1);
+        op->debug_id = atomic_inc_return(&fscache_op_debug_id);
+        op->release = release;
+        INIT_LIST_HEAD(&op->pend_link);
+}
+
+/**
+ * fscache_operation_init_slow - Do additional initialisation of a slow op
+ * @op: The operation to initialise
+ * @processor: The processor function to assign
+ *
+ * Do additional initialisation of an operation as required for slow work.
+ */
+static inline
+void fscache_operation_init_slow(struct fscache_operation *op,
+                                 fscache_operation_processor_t processor)
+{
+        op->processor = processor;
+        slow_work_init(&op->slow_work, &fscache_op_slow_work_ops);
+}
+
+/*
+ * 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 */
+};
+
+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_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 */
+        void (*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);
+
+        /* store the updated auxilliary data on an object */
+        void (*update_object)(struct fscache_object *object);
+
+        /* 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);
+};
+
+/*
+ * 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 */
+        spinlock_t                      lock;
+        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 */
+        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 */
+
+        unsigned long                   flags;
+#define FSCACHE_COOKIE_LOOKING_UP       0       /* T if non-index cookie being looked up still */
+#define FSCACHE_COOKIE_CREATING         1       /* T if non-index object being created still */
+#define FSCACHE_COOKIE_NO_DATA_YET      2       /* T if new object with no cached data yet */
+#define FSCACHE_COOKIE_PENDING_FILL     3       /* T if pending initial fill on object */
+#define FSCACHE_COOKIE_FILLING          4       /* T if filling object incrementally */
+#define FSCACHE_COOKIE_UNAVAILABLE      5       /* T if cookie is unavailable (error, etc) */
+};
+
+extern struct fscache_cookie fscache_fsdef_index;
+
+/*
+ * on-disk cache file or index handle
+ */
+struct fscache_object {
+        enum fscache_object_state {
+                FSCACHE_OBJECT_INIT,            /* object in initial unbound state */
+                FSCACHE_OBJECT_LOOKING_UP,      /* looking up object */
+                FSCACHE_OBJECT_CREATING,        /* creating object */
+
+                /* active states */
+                FSCACHE_OBJECT_AVAILABLE,       /* cleaning up object after creation */
+                FSCACHE_OBJECT_ACTIVE,          /* object is usable */
+                FSCACHE_OBJECT_UPDATING,        /* object is updating */
+
+                /* terminal states */
+                FSCACHE_OBJECT_DYING,           /* object waiting for accessors to finish */
+                FSCACHE_OBJECT_LC_DYING,        /* object cleaning up after lookup/create */
+                FSCACHE_OBJECT_ABORT_INIT,      /* abort the init state */
+                FSCACHE_OBJECT_RELEASING,       /* releasing object */
+                FSCACHE_OBJECT_RECYCLING,       /* retiring object */
+                FSCACHE_OBJECT_WITHDRAWING,     /* withdrawing object */
+                FSCACHE_OBJECT_DEAD,            /* object is now dead */
+        } state;
+
+        int                     debug_id;       /* debugging ID */
+        int                     n_children;     /* number of child objects */
+        int                     n_ops;          /* number of ops outstanding 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 */
+        spinlock_t              lock;           /* state and operations lock */
+
+        unsigned long           lookup_jif;     /* time at which lookup started */
+        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) */
+#define FSCACHE_OBJECT_EV_REQUEUE       0       /* T if object should be requeued */
+#define FSCACHE_OBJECT_EV_UPDATE        1       /* T if object should be updated */
+#define FSCACHE_OBJECT_EV_CLEARED       2       /* T if accessors all gone */
+#define FSCACHE_OBJECT_EV_ERROR         3       /* T if fatal error occurred during processing */
+#define FSCACHE_OBJECT_EV_RELEASE       4       /* T if netfs requested object release */
+#define FSCACHE_OBJECT_EV_RETIRE        5       /* T if netfs requested object retirement */
+#define FSCACHE_OBJECT_EV_WITHDRAW      6       /* T if cache requested object withdrawal */
+
+        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 */
+
+        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 slow_work        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 */
+};
+
+extern const char *fscache_object_states[];
+
+#define fscache_object_is_active(obj)                         \
+        (!test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) &&  \
+         (obj)->state >= FSCACHE_OBJECT_AVAILABLE &&          \
+         (obj)->state < FSCACHE_OBJECT_DYING)
+
+extern const struct slow_work_ops fscache_object_slow_work_ops;
+
+/**
+ * fscache_object_init - Initialise a cache object description
+ * @object: Object description
+ *
+ * Initialise a cache object description to its basic values.
+ *
+ * See Documentation/filesystems/caching/backend-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_object_init(struct fscache_object *object,
+                         struct fscache_cookie *cookie,
+                         struct fscache_cache *cache)
+{
+        atomic_inc(&cache->object_count);
+
+        object->state = FSCACHE_OBJECT_INIT;
+        spin_lock_init(&object->lock);
+        INIT_LIST_HEAD(&object->cache_link);
+        INIT_HLIST_NODE(&object->cookie_link);
+        vslow_work_init(&object->work, &fscache_object_slow_work_ops);
+        INIT_LIST_HEAD(&object->dependents);
+        INIT_LIST_HEAD(&object->dep_link);
+        INIT_LIST_HEAD(&object->pending_ops);
+        object->n_children = 0;
+        object->n_ops = object->n_in_progress = object->n_exclusive = 0;
+        object->events = object->event_mask = 0;
+        object->flags = 0;
+        object->store_limit = 0;
+        object->cache = cache;
+        object->cookie = cookie;
+        object->parent = NULL;
+}
+
+extern void fscache_object_lookup_negative(struct fscache_object *object);
+extern void fscache_obtained_object(struct fscache_object *object);
+
+/**
+ * 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 = 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);
+}
+
+/*
+ * out-of-line cache backend functions
+ */
+extern void fscache_init_cache(struct fscache_cache *cache,
+                               const struct fscache_cache_ops *ops,
+                               const char *idfmt,
+                               ...) __attribute__ ((format (printf, 3, 4)));
+
+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_pages_cached(struct fscache_retrieval *op,
+                                      struct pagevec *pagevec);
+
+extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
+                                               const void *data,
+                                               uint16_t datalen);
+
+#endif /* _LINUX_FSCACHE_CACHE_H */
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
new file mode 100644
index 000000000000..6d8ee466e0a0
--- /dev/null
+++ b/include/linux/fscache.h
@@ -0,0 +1,618 @@
+/* General filesystem caching 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/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>
+
+#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);
+
+        /* get an index key
+         * - should store the key data in the buffer
+         * - should return the amount of amount stored
+         * - not permitted to return an error
+         * - the netfs data from the cookie being used as the source is
+         *   presented
+         */
+        uint16_t (*get_key)(const void *cookie_netfs_data,
+                            void *buffer,
+                            uint16_t bufmax);
+
+        /* get certain file attributes from the netfs data
+         * - this function can be absent for an index
+         * - not permitted to return an error
+         * - the netfs data from the cookie being used as the source is
+         *   presented
+         */
+        void (*get_attr)(const void *cookie_netfs_data, uint64_t *size);
+
+        /* get the auxilliary data from netfs data
+         * - this function can be absent if the index carries no state data
+         * - should store the auxilliary data in the buffer
+         * - should return the amount of amount stored
+         * - not permitted to return an error
+         * - the netfs data from the cookie being used as the source is
+         *   presented
+         */
+        uint16_t (*get_aux)(const void *cookie_netfs_data,
+                            void *buffer,
+                            uint16_t bufmax);
+
+        /* 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 auxilliary data
+         */
+        enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
+                                           const void *data,
+                                           uint16_t datalen);
+
+        /* 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 pages that now have cache metadata retained
+         * - this function should mark the specified pages as now being cached
+         * - the pages will have been marked with PG_fscache before this is
+         *   called, so this is optional
+         */
+        void (*mark_pages_cached)(void *cookie_netfs_data,
+                                  struct address_space *mapping,
+                                  struct pagevec *cached_pvec);
+
+        /* indicate the cookie is no longer cached
+         * - this function is called when the backing store currently caching
+         *   a cookie is removed
+         * - the netfs should use this to clean up any markers indicating
+         *   cached pages
+         * - this is mandatory for any object that may have data
+         */
+        void (*now_uncached)(void *cookie_netfs_data);
+};
+
+/*
+ * 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;
+        struct list_head                link;           /* internal link */
+};
+
+/*
+ * 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 *,
+        void *);
+extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
+extern void __fscache_update_cookie(struct fscache_cookie *);
+extern int __fscache_attr_changed(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 *, 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 *);
+
+/**
+ * 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
+ * @netfs_data: An arbitrary piece of data to be kept in the cookie to
+ * represent the cache object to the netfs
+ *
+ * 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,
+        void *netfs_data)
+{
+        if (fscache_cookie_valid(parent))
+                return __fscache_acquire_cookie(parent, def, netfs_data);
+        else
+                return NULL;
+}
+
+/**
+ * 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.txt for a complete
+ * description.
+ */
+static inline
+void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
+{
+        if (fscache_cookie_valid(cookie))
+                __fscache_relinquish_cookie(cookie, retire);
+}
+
+/**
+ * fscache_update_cookie - Request that a cache object be updated
+ * @cookie: The cookie representing the cache object
+ *
+ * Request an update of the index data for the cache object associated with the
+ * cookie.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_update_cookie(struct fscache_cookie *cookie)
+{
+        if (fscache_cookie_valid(cookie))
+                __fscache_update_cookie(cookie);
+}
+
+/**
+ * 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))
+                return __fscache_attr_changed(cookie);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * 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))
+                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
+ * @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))
+                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))
+                return __fscache_alloc_page(cookie, page, gfp);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * fscache_write_page - Request storage of a page in the cache
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page to store
+ * @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,
+                       gfp_t gfp)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_write_page(cookie, page, 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);
+}
+
+#endif /* _LINUX_FSCACHE_H */
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index bde2557c2a9c..fdffb413b192 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -185,6 +185,9 @@ struct nfs_inode {
         fmode_t                  delegation_state;
         struct rw_semaphore     rwsem;
 #endif /* CONFIG_NFS_V4*/
+#ifdef CONFIG_NFS_FSCACHE
+        struct fscache_cookie   *fscache;
+#endif
         struct inode            vfs_inode;
 };
 
@@ -207,6 +210,8 @@ struct nfs_inode {
 #define NFS_INO_ACL_LRU_SET     (2)             /* Inode is on the LRU list */
 #define NFS_INO_MOUNTPOINT      (3)             /* inode is remote mountpoint */
 #define NFS_INO_FLUSHING        (4)             /* inode is flushing out data */
+#define NFS_INO_FSCACHE         (5)             /* inode can be cached by FS-Cache */
+#define NFS_INO_FSCACHE_LOCK    (6)             /* FS-Cache cookie management lock */
 
 static inline struct nfs_inode *NFS_I(const struct inode *inode)
 {
@@ -260,6 +265,11 @@ static inline int NFS_STALE(const struct inode *inode)
         return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
 }
 
+static inline int NFS_FSCACHE(const struct inode *inode)
+{
+        return test_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+}
+
 static inline __u64 NFS_FILEID(const struct inode *inode)
 {
         return NFS_I(inode)->fileid;
@@ -506,6 +516,8 @@ extern int  nfs_readpages(struct file *, struct address_space *,
                 struct list_head *, unsigned);
 extern int  nfs_readpage_result(struct rpc_task *, struct nfs_read_data *);
 extern void nfs_readdata_release(void *data);
+extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
+                               struct page *);
 
 /*
  * Allocate nfs_read_data structures
@@ -583,6 +595,7 @@ extern void * nfs_root_data(void);
 #define NFSDBG_CALLBACK         0x0100
 #define NFSDBG_CLIENT           0x0200
 #define NFSDBG_MOUNT            0x0400
+#define NFSDBG_FSCACHE          0x0800
 #define NFSDBG_ALL              0xFFFF
 
 #ifdef __KERNEL__
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 29b1e40dce99..6ad75948cbf7 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -64,6 +64,10 @@ struct nfs_client {
         char                    cl_ipaddr[48];
         unsigned char           cl_id_uniquifier;
 #endif
+
+#ifdef CONFIG_NFS_FSCACHE
+        struct fscache_cookie   *fscache;       /* client index cache cookie */
+#endif
 };
 
 /*
@@ -96,12 +100,19 @@ struct nfs_server {
         unsigned int            acdirmin;
         unsigned int            acdirmax;
         unsigned int            namelen;
+        unsigned int            options;        /* extra options enabled by mount */
+#define NFS_OPTION_FSCACHE      0x00000001      /* - local caching enabled */
 
         struct nfs_fsid         fsid;
         __u64                   maxfilesize;    /* maximum file size */
         unsigned long           mount_time;     /* when this fs was mounted */
         dev_t                   s_dev;          /* superblock dev numbers */
 
+#ifdef CONFIG_NFS_FSCACHE
+        struct nfs_fscache_key  *fscache_key;   /* unique key for superblock */
+        struct fscache_cookie   *fscache;       /* superblock cookie */
+#endif
+
 #ifdef CONFIG_NFS_V4
         u32                     attr_bitmask[2];/* V4 bitmask representing the set
                                                    of attributes supported on this
diff --git a/include/linux/nfs_iostat.h b/include/linux/nfs_iostat.h
index 1cb9a3fed2b3..68b10f5f8907 100644
--- a/include/linux/nfs_iostat.h
+++ b/include/linux/nfs_iostat.h
@@ -116,4 +116,16 @@ enum nfs_stat_eventcounters {
         __NFSIOS_COUNTSMAX,
 };
 
+/*
+ * NFS local caching servicing counters
+ */
+enum nfs_stat_fscachecounters {
+        NFSIOS_FSCACHE_PAGES_READ_OK,
+        NFSIOS_FSCACHE_PAGES_READ_FAIL,
+        NFSIOS_FSCACHE_PAGES_WRITTEN_OK,
+        NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL,
+        NFSIOS_FSCACHE_PAGES_UNCACHED,
+        __NFSIOS_FSCACHEMAX,
+};
+
 #endif  /* _LINUX_NFS_IOSTAT */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 61df1779b2a5..62214c7d2d93 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -82,6 +82,7 @@ enum pageflags {
         PG_arch_1,
         PG_reserved,
         PG_private,             /* If pagecache, has fs-private data */
+        PG_private_2,           /* If pagecache, has fs aux data */
         PG_writeback,           /* Page is under writeback */
 #ifdef CONFIG_PAGEFLAGS_EXTENDED
         PG_head,                /* A head page */
@@ -108,6 +109,12 @@ enum pageflags {
         /* Filesystems */
         PG_checked = PG_owner_priv_1,
 
+        /* Two page bits are conscripted by FS-Cache to maintain local caching
+         * state.  These bits are set on pages belonging to the netfs's inodes
+         * when those inodes are being locally cached.
+         */
+        PG_fscache = PG_private_2,      /* page backed by cache */
+
         /* XEN */
         PG_pinned = PG_owner_priv_1,
         PG_savepinned = PG_dirty,
@@ -182,7 +189,7 @@ static inline int TestClearPage##uname(struct page *page) { return 0; }
 
 struct page;    /* forward declaration */
 
-TESTPAGEFLAG(Locked, locked)
+TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked)
 PAGEFLAG(Error, error)
 PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
 PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
@@ -194,8 +201,6 @@ PAGEFLAG(Checked, checked)		/* Used by some filesystems */
 PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned)     /* Xen */
 PAGEFLAG(SavePinned, savepinned);                       /* Xen */
 PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
-PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
-        __SETPAGEFLAG(Private, private)
 PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
 
 __PAGEFLAG(SlobPage, slob_page)
@@ -205,6 +210,16 @@ __PAGEFLAG(SlubFrozen, slub_frozen)
 __PAGEFLAG(SlubDebug, slub_debug)
 
 /*
+ * Private page markings that may be used by the filesystem that owns the page
+ * for its own purposes.
+ * - PG_private and PG_private_2 cause releasepage() and co to be invoked
+ */
+PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
+        __CLEARPAGEFLAG(Private, private)
+PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
+PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
+
+/*
  * Only test-and-set exist for PG_writeback.  The unconditional operators are
  * risky: they bypass page accounting.
  */
@@ -384,9 +399,10 @@ static inline void __ClearPageTail(struct page *page)
  * these flags set.  It they are, there is a problem.
  */
 #define PAGE_FLAGS_CHECK_AT_FREE \
-        (1 << PG_lru   | 1 << PG_private   | 1 << PG_locked | \
-         1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
-         1 << PG_slab  | 1 << PG_swapcache | 1 << PG_active | \
+        (1 << PG_lru     | 1 << PG_locked    | \
+         1 << PG_private | 1 << PG_private_2 | \
+         1 << PG_buddy   | 1 << PG_writeback | 1 << PG_reserved | \
+         1 << PG_slab    | 1 << PG_swapcache | 1 << PG_active | \
          __PG_UNEVICTABLE | __PG_MLOCKED)
 
 /*
@@ -397,4 +413,16 @@ static inline void __ClearPageTail(struct page *page)
 #define PAGE_FLAGS_CHECK_AT_PREP        ((1 << NR_PAGEFLAGS) - 1)
 
 #endif /* !__GENERATING_BOUNDS_H */
+
+/**
+ * page_has_private - Determine if page has private stuff
+ * @page: The page to be checked
+ *
+ * Determine if a page has private stuff, indicating that release routines
+ * should be invoked upon it.
+ */
+#define page_has_private(page)                  \
+        ((page)->flags & ((1 << PG_private) |   \
+                          (1 << PG_private_2)))
+
 #endif  /* PAGE_FLAGS_H */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 076a7dc67c2b..34da5230faab 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -384,6 +384,11 @@ static inline void wait_on_page_writeback(struct page *page)
 extern void end_page_writeback(struct page *page);
 
 /*
+ * Add an arbitrary waiter to a page's wait queue
+ */
+extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter);
+
+/*
  * Fault a userspace page into pagetables.  Return non-zero on a fault.
  *
  * This assumes that two userspace pages are always sufficient.  That's
diff --git a/include/linux/slow-work.h b/include/linux/slow-work.h
new file mode 100644
index 000000000000..85958277f83d
--- /dev/null
+++ b/include/linux/slow-work.h
@@ -0,0 +1,95 @@
+/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
+ *
+ * Copyright (C) 2008 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 Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ *
+ * See Documentation/slow-work.txt
+ */
+
+#ifndef _LINUX_SLOW_WORK_H
+#define _LINUX_SLOW_WORK_H
+
+#ifdef CONFIG_SLOW_WORK
+
+#include <linux/sysctl.h>
+
+struct slow_work;
+
+/*
+ * The operations used to support slow work items
+ */
+struct slow_work_ops {
+        /* get a ref on a work item
+         * - return 0 if successful, -ve if not
+         */
+        int (*get_ref)(struct slow_work *work);
+
+        /* discard a ref to a work item */
+        void (*put_ref)(struct slow_work *work);
+
+        /* execute a work item */
+        void (*execute)(struct slow_work *work);
+};
+
+/*
+ * A slow work item
+ * - A reference is held on the parent object by the thread pool when it is
+ *   queued
+ */
+struct slow_work {
+        unsigned long           flags;
+#define SLOW_WORK_PENDING       0       /* item pending (further) execution */
+#define SLOW_WORK_EXECUTING     1       /* item currently executing */
+#define SLOW_WORK_ENQ_DEFERRED  2       /* item enqueue deferred */
+#define SLOW_WORK_VERY_SLOW     3       /* item is very slow */
+        const struct slow_work_ops *ops; /* operations table for this item */
+        struct list_head        link;   /* link in queue */
+};
+
+/**
+ * slow_work_init - Initialise a slow work item
+ * @work: The work item to initialise
+ * @ops: The operations to use to handle the slow work item
+ *
+ * Initialise a slow work item.
+ */
+static inline void slow_work_init(struct slow_work *work,
+                                  const struct slow_work_ops *ops)
+{
+        work->flags = 0;
+        work->ops = ops;
+        INIT_LIST_HEAD(&work->link);
+}
+
+/**
+ * slow_work_init - Initialise a very slow work item
+ * @work: The work item to initialise
+ * @ops: The operations to use to handle the slow work item
+ *
+ * Initialise a very slow work item.  This item will be restricted such that
+ * only a certain number of the pool threads will be able to execute items of
+ * this type.
+ */
+static inline void vslow_work_init(struct slow_work *work,
+                                   const struct slow_work_ops *ops)
+{
+        work->flags = 1 << SLOW_WORK_VERY_SLOW;
+        work->ops = ops;
+        INIT_LIST_HEAD(&work->link);
+}
+
+extern int slow_work_enqueue(struct slow_work *work);
+extern int slow_work_register_user(void);
+extern void slow_work_unregister_user(void);
+
+#ifdef CONFIG_SYSCTL
+extern ctl_table slow_work_sysctls[];
+#endif
+
+#endif /* CONFIG_SLOW_WORK */
+#endif /* _LINUX_SLOW_WORK_H */