/*
   * Copyright (C) 2007 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/highmem.h>

  
  /* this is some deeply nasty code.  ctree.h has a different
   * definition for this BTRFS_SETGET_FUNCS macro, behind a #ifndef
   *
   * The end result is that anyone who #includes ctree.h gets a
   * declaration for the btrfs_set_foo functions and btrfs_foo functions
   *
   * This file declares the macros and then #includes ctree.h, which results
   * in cpp creating the function here based on the template below.
   *
   * These setget functions do all the extent_buffer related mapping
   * required to efficiently read and write specific fields in the extent
   * buffers.  Every pointer to metadata items in btrfs is really just
   * an unsigned long offset into the extent buffer which has been
   * cast to a specific type.  This gives us all the gcc type checking.
   *
   * The extent buffer api is used to do all the kmapping and page
   * spanning work required to get extent buffers in highmem and have
   * a metadata blocksize different from the page size.

   *
   * The macro starts with a simple function prototype declaration so that
   * sparse won't complain about it being static.

   */

  #define BTRFS_SETGET_FUNCS(name, type, member, bits)			\

  u##bits btrfs_##name(struct extent_buffer *eb, type *s);		\
  void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val);	\

  u##bits btrfs_##name(struct extent_buffer *eb,				\
  				   type *s)				\
  {									\

  	unsigned long part_offset = (unsigned long)s;			\
  	unsigned long offset = part_offset + offsetof(type, member);	\
  	type *p;							\

  	int err;						\
  	char *kaddr;						\
  	unsigned long map_start;				\
  	unsigned long map_len;					\
  	u##bits res;						\
  	err = map_private_extent_buffer(eb, offset,		\
  			sizeof(((type *)0)->member),		\
  			&kaddr, &map_start, &map_len);		\
  	if (err) {						\
  		__le##bits leres;				\
  		read_eb_member(eb, s, type, member, &leres);	\
  		return le##bits##_to_cpu(leres);		\
  	}							\
  	p = (type *)(kaddr + part_offset - map_start);		\
  	res = le##bits##_to_cpu(p->member);			\
  	return res;						\

  }									\
  void btrfs_set_##name(struct extent_buffer *eb,				\
  				    type *s, u##bits val)		\
  {									\

  	unsigned long part_offset = (unsigned long)s;			\
  	unsigned long offset = part_offset + offsetof(type, member);	\
  	type *p;							\

  	int err;						\
  	char *kaddr;						\
  	unsigned long map_start;				\
  	unsigned long map_len;					\
  	err = map_private_extent_buffer(eb, offset,		\
  			sizeof(((type *)0)->member),		\
  			&kaddr, &map_start, &map_len);		\
  	if (err) {						\
  		__le##bits val2;				\
  		val2 = cpu_to_le##bits(val);			\
  		write_eb_member(eb, s, type, member, &val2);	\
  		return;						\
  	}							\
  	p = (type *)(kaddr + part_offset - map_start);		\
  	p->member = cpu_to_le##bits(val);			\

  }
  
  #include "ctree.h"

  void btrfs_node_key(struct extent_buffer *eb,
  		    struct btrfs_disk_key *disk_key, int nr)
  {
  	unsigned long ptr = btrfs_node_key_ptr_offset(nr);

  	read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
  		       struct btrfs_key_ptr, key, disk_key);
  }