1/*
2 * Copyright (C) 2007 Oracle.  All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/highmem.h>
20
21/* this is some deeply nasty code.  ctree.h has a different
22 * definition for this BTRFS_SETGET_FUNCS macro, behind a #ifndef
23 *
24 * The end result is that anyone who #includes ctree.h gets a
25 * declaration for the btrfs_set_foo functions and btrfs_foo functions
26 *
27 * This file declares the macros and then #includes ctree.h, which results
28 * in cpp creating the function here based on the template below.
29 *
30 * These setget functions do all the extent_buffer related mapping
31 * required to efficiently read and write specific fields in the extent
32 * buffers.  Every pointer to metadata items in btrfs is really just
33 * an unsigned long offset into the extent buffer which has been
34 * cast to a specific type.  This gives us all the gcc type checking.
35 *
36 * The extent buffer api is used to do all the kmapping and page
37 * spanning work required to get extent buffers in highmem and have
38 * a metadata blocksize different from the page size.
39 *
40 * The macro starts with a simple function prototype declaration so that
41 * sparse won't complain about it being static.
42 */
43
44#define BTRFS_SETGET_FUNCS(name, type, member, bits)			\
45u##bits btrfs_##name(struct extent_buffer *eb, type *s);		\
46void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val);	\
47u##bits btrfs_##name(struct extent_buffer *eb,				\
48				   type *s)				\
49{									\
50	unsigned long part_offset = (unsigned long)s;			\
51	unsigned long offset = part_offset + offsetof(type, member);	\
52	type *p;							\
53	int err;						\
54	char *kaddr;						\
55	unsigned long map_start;				\
56	unsigned long map_len;					\
57	u##bits res;						\
58	err = map_private_extent_buffer(eb, offset,		\
59			sizeof(((type *)0)->member),		\
60			&kaddr, &map_start, &map_len);		\
61	if (err) {						\
62		__le##bits leres;				\
63		read_eb_member(eb, s, type, member, &leres);	\
64		return le##bits##_to_cpu(leres);		\
65	}							\
66	p = (type *)(kaddr + part_offset - map_start);		\
67	res = le##bits##_to_cpu(p->member);			\
68	return res;						\
69}									\
70void btrfs_set_##name(struct extent_buffer *eb,				\
71				    type *s, u##bits val)		\
72{									\
73	unsigned long part_offset = (unsigned long)s;			\
74	unsigned long offset = part_offset + offsetof(type, member);	\
75	type *p;							\
76	int err;						\
77	char *kaddr;						\
78	unsigned long map_start;				\
79	unsigned long map_len;					\
80	err = map_private_extent_buffer(eb, offset,		\
81			sizeof(((type *)0)->member),		\
82			&kaddr, &map_start, &map_len);		\
83	if (err) {						\
84		__le##bits val2;				\
85		val2 = cpu_to_le##bits(val);			\
86		write_eb_member(eb, s, type, member, &val2);	\
87		return;						\
88	}							\
89	p = (type *)(kaddr + part_offset - map_start);		\
90	p->member = cpu_to_le##bits(val);			\
91}
92
93#include "ctree.h"
94
95void btrfs_node_key(struct extent_buffer *eb,
96		    struct btrfs_disk_key *disk_key, int nr)
97{
98	unsigned long ptr = btrfs_node_key_ptr_offset(nr);
99	read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
100		       struct btrfs_key_ptr, key, disk_key);
101}
102