--- /dev/null
+/* fscache.h: general filesystem caching interface
+ *
+ * Copyright (C) 2004-5 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>
+
+struct pagevec;
+struct fscache_cache_tag;
+struct fscache_cookie;
+struct fscache_netfs;
+struct fscache_netfs_operations;
+
+typedef void (*fscache_rw_complete_t)(struct page *page,
+ void *context,
+ int error);
+
+/* result of index entry consultation */
+typedef enum {
+ FSCACHE_CHECKAUX_OKAY, /* entry okay as is */
+ FSCACHE_CHECKAUX_NEEDS_UPDATE, /* entry requires update */
+ FSCACHE_CHECKAUX_OBSOLETE, /* entry requires deletion */
+} fscache_checkaux_t;
+
+/*****************************************************************************/
+/*
+ * 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
+ */
+ fscache_checkaux_t (*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
+ */
+ 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);
+};
+
+/* pattern used to fill dead space in an index entry */
+#define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
+
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern struct fscache_cookie *__fscache_acquire_cookie(struct fscache_cookie *parent,
+ struct fscache_cookie_def *def,
+ void *netfs_data);
+
+extern void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
+ int retire);
+
+extern void __fscache_update_cookie(struct fscache_cookie *cookie);
+#endif
+
+static inline
+struct fscache_cookie *fscache_acquire_cookie(struct fscache_cookie *parent,
+ struct fscache_cookie_def *def,
+ void *netfs_data)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (parent)
+ return __fscache_acquire_cookie(parent, def, netfs_data);
+#endif
+ return NULL;
+}
+
+static inline
+void fscache_relinquish_cookie(struct fscache_cookie *cookie,
+ int retire)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ __fscache_relinquish_cookie(cookie, retire);
+#endif
+}
+
+static inline
+void fscache_update_cookie(struct fscache_cookie *cookie)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ __fscache_update_cookie(cookie);
+#endif
+}
+
+/*****************************************************************************/
+/*
+ * pin or unpin a cookie in a cache
+ * - only available for data cookies
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern int __fscache_pin_cookie(struct fscache_cookie *cookie);
+extern void __fscache_unpin_cookie(struct fscache_cookie *cookie);
+#endif
+
+static inline
+int fscache_pin_cookie(struct fscache_cookie *cookie)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_pin_cookie(cookie);
+#endif
+ return -ENOBUFS;
+}
+
+static inline
+void fscache_unpin_cookie(struct fscache_cookie *cookie)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ __fscache_unpin_cookie(cookie);
+#endif
+}
+
+/*****************************************************************************/
+/*
+ * 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 fscache_netfs_operations *ops;
+ struct list_head link; /* internal link */
+};
+
+struct fscache_netfs_operations
+{
+};
+
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern int __fscache_register_netfs(struct fscache_netfs *netfs);
+extern void __fscache_unregister_netfs(struct fscache_netfs *netfs);
+#endif
+
+static inline
+int fscache_register_netfs(struct fscache_netfs *netfs)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ return __fscache_register_netfs(netfs);
+#else
+ return 0;
+#endif
+}
+
+static inline
+void fscache_unregister_netfs(struct fscache_netfs *netfs)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ __fscache_unregister_netfs(netfs);
+#endif
+}
+
+/*****************************************************************************/
+/*
+ * look up a cache tag
+ * - cache tags are used to select specific caches in which to cache indexes
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *name);
+extern void __fscache_release_cache_tag(struct fscache_cache_tag *tag);
+#endif
+
+static inline
+struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ return __fscache_lookup_cache_tag(name);
+#else
+ return NULL;
+#endif
+}
+
+static inline
+void fscache_release_cache_tag(struct fscache_cache_tag *tag)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ __fscache_release_cache_tag(tag);
+#endif
+}
+
+/*****************************************************************************/
+/*
+ * set the data size on a cached object
+ * - no pages beyond the end of the object will be accessible
+ * - returns -ENOBUFS if the file is not backed
+ * - returns -ENOSPC if a pinned file of that size can't be stored
+ * - returns 0 if okay
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern int __fscache_set_i_size(struct fscache_cookie *cookie, loff_t i_size);
+#endif
+
+static inline
+int fscache_set_i_size(struct fscache_cookie *cookie, loff_t i_size)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_set_i_size(cookie, i_size);
+#endif
+ return -ENOBUFS;
+}
+
+/*****************************************************************************/
+/*
+ * reserve data space for a cached object
+ * - returns -ENOBUFS if the file is not backed
+ * - returns -ENOSPC if there isn't enough space to honour the reservation
+ * - returns 0 if okay
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern int __fscache_reserve_space(struct fscache_cookie *cookie, loff_t size);
+#endif
+
+static inline
+int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_reserve_space(cookie, size);
+#endif
+ return -ENOBUFS;
+}
+
+/*****************************************************************************/
+/*
+ * read a page from the cache or allocate a block in which to store it
+ * - if the page is not backed by a file:
+ * - -ENOBUFS will be returned and nothing more will be done
+ * - else if the page is backed by a block in the cache:
+ * - a read will be started which will call end_io_func on completion
+ * - else if the page is unbacked:
+ * - a block will be allocated
+ * - -ENODATA will be returned
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern 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);
+#endif
+
+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 defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_read_or_alloc_page(cookie, page, end_io_func,
+ context, gfp);
+#endif
+ return -ENOBUFS;
+}
+
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern 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);
+#endif
+
+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 defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_read_or_alloc_pages(cookie, mapping, pages,
+ nr_pages, end_io_func,
+ context, gfp);
+#endif
+ return -ENOBUFS;
+}
+
+/*
+ * allocate a block in which to store a page
+ * - if the page is not backed by a file:
+ * - -ENOBUFS will be returned and nothing more will be done
+ * - else
+ * - a block will be allocated if there isn't one
+ * - 0 will be returned
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern int __fscache_alloc_page(struct fscache_cookie *cookie,
+ struct page *page,
+ gfp_t gfp);
+#endif
+
+static inline
+int fscache_alloc_page(struct fscache_cookie *cookie,
+ struct page *page,
+ gfp_t gfp)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_alloc_page(cookie, page, gfp);
+#endif
+ return -ENOBUFS;
+}
+
+/*
+ * request a page be stored in the cache
+ * - this request may be ignored if no cache block is currently allocated, in
+ * which case it:
+ * - returns -ENOBUFS
+ * - if a cache block was already allocated:
+ * - a BIO will be dispatched to write the page (end_io_func will be called
+ * from the completion function)
+ * - returns 0
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern int __fscache_write_page(struct fscache_cookie *cookie,
+ struct page *page,
+ fscache_rw_complete_t end_io_func,
+ void *context,
+ gfp_t gfp);
+
+extern int __fscache_write_pages(struct fscache_cookie *cookie,
+ struct pagevec *pagevec,
+ fscache_rw_complete_t end_io_func,
+ void *context,
+ gfp_t gfp);
+#endif
+
+static inline
+int fscache_write_page(struct fscache_cookie *cookie,
+ struct page *page,
+ fscache_rw_complete_t end_io_func,
+ void *context,
+ gfp_t gfp)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_write_page(cookie, page, end_io_func,
+ context, gfp);
+#endif
+ return -ENOBUFS;
+}
+
+static inline
+int fscache_write_pages(struct fscache_cookie *cookie,
+ struct pagevec *pagevec,
+ fscache_rw_complete_t end_io_func,
+ void *context,
+ gfp_t gfp)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ return __fscache_write_pages(cookie, pagevec, end_io_func,
+ context, gfp);
+#endif
+ return -ENOBUFS;
+}
+
+/*
+ * indicate that caching is no longer required on a page
+ * - note: cannot cancel any outstanding BIOs between this page and the cache
+ */
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+extern void __fscache_uncache_page(struct fscache_cookie *cookie,
+ struct page *page);
+extern void __fscache_uncache_pages(struct fscache_cookie *cookie,
+ struct pagevec *pagevec);
+#endif
+
+static inline
+void fscache_uncache_page(struct fscache_cookie *cookie,
+ struct page *page)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ __fscache_uncache_page(cookie, page);
+#endif
+}
+
+static inline
+void fscache_uncache_pagevec(struct fscache_cookie *cookie,
+ struct pagevec *pagevec)
+{
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+ if (cookie)
+ __fscache_uncache_pages(cookie, pagevec);
+#endif
+}
+
+#endif /* _LINUX_FSCACHE_H */
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