/* NFS filesystem cache interface definitions
   *
   * 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.
   */
  
  #ifndef _NFS_FSCACHE_H
  #define _NFS_FSCACHE_H
  
  #include <linux/nfs_fs.h>
  #include <linux/nfs_mount.h>
  #include <linux/nfs4_mount.h>
  #include <linux/fscache.h>
  
  #ifdef CONFIG_NFS_FSCACHE
  
  /*
   * set of NFS FS-Cache objects that form a superblock key
   */
  struct nfs_fscache_key {
  	struct rb_node		node;
  	struct nfs_client	*nfs_client;	/* the server */
  
  	/* the elements of the unique key - as used by nfs_compare_super() and
  	 * nfs_compare_mount_options() to distinguish superblocks */
  	struct {
  		struct {
  			unsigned long	s_flags;	/* various flags
  							 * (& NFS_MS_MASK) */
  		} super;
  
  		struct {
  			struct nfs_fsid fsid;
  			int		flags;
  			unsigned int	rsize;		/* read size */
  			unsigned int	wsize;		/* write size */
  			unsigned int	acregmin;	/* attr cache timeouts */
  			unsigned int	acregmax;
  			unsigned int	acdirmin;
  			unsigned int	acdirmax;
  		} nfs_server;
  
  		struct {
  			rpc_authflavor_t au_flavor;
  		} rpc_auth;
  
  		/* uniquifier - can be used if nfs_server.flags includes
  		 * NFS_MOUNT_UNSHARED  */
  		u8 uniq_len;
  		char uniquifier[0];
  	} key;
  };
  
  /*
   * fscache-index.c
   */
  extern struct fscache_netfs nfs_fscache_netfs;
  extern const struct fscache_cookie_def nfs_fscache_server_index_def;
  extern const struct fscache_cookie_def nfs_fscache_super_index_def;
  extern const struct fscache_cookie_def nfs_fscache_inode_object_def;
  
  extern int nfs_fscache_register(void);
  extern void nfs_fscache_unregister(void);
  
  /*
   * fscache.c
   */
  extern void nfs_fscache_get_client_cookie(struct nfs_client *);
  extern void nfs_fscache_release_client_cookie(struct nfs_client *);
  
  extern void nfs_fscache_get_super_cookie(struct super_block *, const char *, int);
  extern void nfs_fscache_release_super_cookie(struct super_block *);
  
  extern void nfs_fscache_init_inode(struct inode *);
  extern void nfs_fscache_clear_inode(struct inode *);
  extern void nfs_fscache_open_file(struct inode *, struct file *);
  
  extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
  extern int nfs_fscache_release_page(struct page *, gfp_t);
  
  extern int __nfs_readpage_from_fscache(struct nfs_open_context *,
  				       struct inode *, struct page *);
  extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
  					struct inode *, struct address_space *,
  					struct list_head *, unsigned *);
  extern void __nfs_readpage_to_fscache(struct inode *, struct page *, int);
  
  /*
   * wait for a page to complete writing to the cache
   */
  static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
  						  struct page *page)
  {
  	if (PageFsCache(page))
  		fscache_wait_on_page_write(nfsi->fscache, page);
  }
  
  /*
   * release the caching state associated with a page if undergoing complete page
   * invalidation
   */
  static inline void nfs_fscache_invalidate_page(struct page *page,
  					       struct inode *inode)
  {
  	if (PageFsCache(page))
  		__nfs_fscache_invalidate_page(page, inode);
  }
  
  /*
   * Retrieve a page from an inode data storage object.
   */
  static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
  					    struct inode *inode,
  					    struct page *page)
  {
  	if (NFS_I(inode)->fscache)
  		return __nfs_readpage_from_fscache(ctx, inode, page);
  	return -ENOBUFS;
  }
  
  /*
   * Retrieve a set of pages from an inode data storage object.
   */
  static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
  					     struct inode *inode,
  					     struct address_space *mapping,
  					     struct list_head *pages,
  					     unsigned *nr_pages)
  {
  	if (NFS_I(inode)->fscache)
  		return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
  						    nr_pages);
  	return -ENOBUFS;
  }
  
  /*
   * Store a page newly fetched from the server in an inode data storage object
   * in the cache.
   */
  static inline void nfs_readpage_to_fscache(struct inode *inode,
  					   struct page *page,
  					   int sync)
  {
  	if (PageFsCache(page))
  		__nfs_readpage_to_fscache(inode, page, sync);
  }
  
  /*
   * Invalidate the contents of fscache for this inode.  This will not sleep.
   */
  static inline void nfs_fscache_invalidate(struct inode *inode)
  {
  	fscache_invalidate(NFS_I(inode)->fscache);
  }
  
  /*
   * Wait for an object to finish being invalidated.
   */
  static inline void nfs_fscache_wait_on_invalidate(struct inode *inode)
  {
  	fscache_wait_on_invalidate(NFS_I(inode)->fscache);
  }
  
  /*
   * indicate the client caching state as readable text
   */
  static inline const char *nfs_server_fscache_state(struct nfs_server *server)
  {
  	if (server->fscache && (server->options & NFS_OPTION_FSCACHE))
  		return "yes";
  	return "no ";
  }
  
  #else /* CONFIG_NFS_FSCACHE */
  static inline int nfs_fscache_register(void) { return 0; }
  static inline void nfs_fscache_unregister(void) {}
  
  static inline void nfs_fscache_get_client_cookie(struct nfs_client *clp) {}
  static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
  
  static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
  
  static inline void nfs_fscache_init_inode(struct inode *inode) {}
  static inline void nfs_fscache_clear_inode(struct inode *inode) {}
  static inline void nfs_fscache_open_file(struct inode *inode,
  					 struct file *filp) {}
  
  static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
  {
  	return 1; /* True: may release page */
  }
  static inline void nfs_fscache_invalidate_page(struct page *page,
  					       struct inode *inode) {}
  static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
  						  struct page *page) {}
  
  static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
  					    struct inode *inode,
  					    struct page *page)
  {
  	return -ENOBUFS;
  }
  static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
  					     struct inode *inode,
  					     struct address_space *mapping,
  					     struct list_head *pages,
  					     unsigned *nr_pages)
  {
  	return -ENOBUFS;
  }
  static inline void nfs_readpage_to_fscache(struct inode *inode,
  					   struct page *page, int sync) {}
  
  
  static inline void nfs_fscache_invalidate(struct inode *inode) {}
  static inline void nfs_fscache_wait_on_invalidate(struct inode *inode) {}
  
  static inline const char *nfs_server_fscache_state(struct nfs_server *server)
  {
  	return "no ";
  }
  
  #endif /* CONFIG_NFS_FSCACHE */
  #endif /* _NFS_FSCACHE_H */