/*
   * linux/include/linux/nfs_page.h
   *
   * Copyright (C) 2000 Trond Myklebust
   *
   * NFS page cache wrapper.
   */
  
  #ifndef _LINUX_NFS_PAGE_H
  #define _LINUX_NFS_PAGE_H
  
  
  #include <linux/list.h>
  #include <linux/pagemap.h>
  #include <linux/wait.h>

  #include <linux/sunrpc/auth.h>
  #include <linux/nfs_xdr.h>

  #include <linux/kref.h>

  
  /*

   * Valid flags for the radix tree
   */

  #define NFS_PAGE_TAG_LOCKED	0

  #define NFS_PAGE_TAG_COMMIT	1

  
  /*

   * Valid flags for a dirty buffer
   */

  enum {
  	PG_BUSY = 0,

  	PG_MAPPED,

  	PG_CLEAN,
  	PG_NEED_COMMIT,
  	PG_NEED_RESCHED,

  	PG_PNFS_COMMIT,

  	PG_PARTIAL_READ_FAILED,

  };

  struct nfs_inode;

  struct nfs_page {

  	union {
  		struct list_head	wb_list;	/* Defines state of page: */
  		struct pnfs_layout_segment *wb_commit_lseg; /* Used when PG_PNFS_COMMIT set */
  	};

  	struct page		*wb_page;	/* page to read in/write out */
  	struct nfs_open_context	*wb_context;	/* File state context info */

  	struct nfs_lock_context	*wb_lock_context;	/* lock context info */

  	atomic_t		wb_complete;	/* i/os we're waiting for */

  	pgoff_t			wb_index;	/* Offset >> PAGE_CACHE_SHIFT */

  	unsigned int		wb_offset,	/* Offset & ~PAGE_CACHE_MASK */
  				wb_pgbase,	/* Start of page data */
  				wb_bytes;	/* Length of request */

  	struct kref		wb_kref;	/* reference count */

  	unsigned long		wb_flags;
  	struct nfs_writeverf	wb_verf;	/* Commit cookie */
  };

  struct nfs_pageio_descriptor;
  struct nfs_pageio_ops {

  	void	(*pg_init)(struct nfs_pageio_descriptor *, struct nfs_page *);

  	bool	(*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *, struct nfs_page *);
  	int	(*pg_doio)(struct nfs_pageio_descriptor *);
  };

  struct nfs_pageio_descriptor {
  	struct list_head	pg_list;

  	unsigned long		pg_bytes_written;

  	size_t			pg_count;
  	size_t			pg_bsize;
  	unsigned int		pg_base;

  	unsigned char		pg_moreio : 1,
  				pg_recoalesce : 1;

  
  	struct inode		*pg_inode;

  	const struct nfs_pageio_ops *pg_ops;

  	int 			pg_ioflags;
  	int			pg_error;

  	const struct rpc_call_ops *pg_rpc_callops;

  	struct pnfs_layout_segment *pg_lseg;

  };

  #define NFS_WBACK_BUSY(req)	(test_bit(PG_BUSY,&(req)->wb_flags))

  
  extern	struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
  					    struct inode *inode,
  					    struct page *page,
  					    unsigned int offset,
  					    unsigned int count);

  extern	void nfs_release_request(struct nfs_page *req);

  extern	int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *dst,
  			  pgoff_t idx_start, unsigned int npages, int tag);

  extern	void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
  			     struct inode *inode,

  			     const struct nfs_pageio_ops *pg_ops,

  			     size_t bsize,
  			     int how);

  extern	int nfs_pageio_add_request(struct nfs_pageio_descriptor *,
  				   struct nfs_page *);

  extern	void nfs_pageio_complete(struct nfs_pageio_descriptor *desc);

  extern	void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *, pgoff_t);

  extern bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
  				struct nfs_page *prev,
  				struct nfs_page *req);

  extern  int nfs_wait_on_request(struct nfs_page *);
  extern	void nfs_unlock_request(struct nfs_page *req);

  extern	int nfs_set_page_tag_locked(struct nfs_page *req);

  extern  void nfs_clear_page_tag_locked(struct nfs_page *req);

  /*

   * Lock the page of an asynchronous request without getting a new reference

   */
  static inline int
  nfs_lock_request_dontget(struct nfs_page *req)
  {

  	return !test_and_set_bit(PG_BUSY, &req->wb_flags);

  }

  /**
   * nfs_list_add_request - Insert a request into a list
   * @req: request
   * @head: head of list into which to insert the request.
   */
  static inline void
  nfs_list_add_request(struct nfs_page *req, struct list_head *head)
  {
  	list_add_tail(&req->wb_list, head);

  }

  
  /**
   * nfs_list_remove_request - Remove a request from its wb_list
   * @req: request
   */
  static inline void
  nfs_list_remove_request(struct nfs_page *req)
  {
  	if (list_empty(&req->wb_list))
  		return;

  	list_del_init(&req->wb_list);

  }

  static inline struct nfs_page *
  nfs_list_entry(struct list_head *head)
  {
  	return list_entry(head, struct nfs_page, wb_list);
  }
  
  static inline
  loff_t req_offset(struct nfs_page *req)
  {
  	return (((loff_t)req->wb_index) << PAGE_CACHE_SHIFT) + req->wb_offset;
  }
  
  #endif /* _LINUX_NFS_PAGE_H */