| blob | c6ffa58124192a9e069b1464d863b33300bcf6e9 |
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 */
19 #include <linux/highmem.h>
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 */
44 #define BTRFS_SETGET_FUNCS(name, type, member, bits) \
45 u##bits btrfs_##name(struct extent_buffer *eb, type *s); \
46 void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val); \
47 void btrfs_set_token_##name(struct extent_buffer *eb, type *s, u##bits val, struct btrfs_map_token *token); \
48 u##bits btrfs_token_##name(struct extent_buffer *eb, \
49 type *s, struct btrfs_map_token *token) \
50 { \
51 unsigned long part_offset = (unsigned long)s; \
52 unsigned long offset = part_offset + offsetof(type, member); \
53 type *p; \
54 int err; \
55 char *kaddr; \
56 unsigned long map_start; \
57 unsigned long map_len; \
58 unsigned long mem_len = sizeof(((type *)0)->member); \
59 u##bits res; \
60 if (token && token->kaddr && token->offset <= offset && \
61 token->eb == eb && \
62 (token->offset + PAGE_CACHE_SIZE >= offset + mem_len)) { \
63 kaddr = token->kaddr; \
64 p = (type *)(kaddr + part_offset - token->offset); \
65 res = le##bits##_to_cpu(p->member); \
66 return res; \
67 } \
68 err = map_private_extent_buffer(eb, offset, \
69 mem_len, \
70 &kaddr, &map_start, &map_len); \
71 if (err) { \
72 __le##bits leres; \
73 read_eb_member(eb, s, type, member, &leres); \
74 return le##bits##_to_cpu(leres); \
75 } \
76 p = (type *)(kaddr + part_offset - map_start); \
77 res = le##bits##_to_cpu(p->member); \
78 if (token) { \
79 token->kaddr = kaddr; \
80 token->offset = map_start; \
81 token->eb = eb; \
82 } \
83 return res; \
84 } \
85 void btrfs_set_token_##name(struct extent_buffer *eb, \
86 type *s, u##bits val, struct btrfs_map_token *token) \
87 { \
88 unsigned long part_offset = (unsigned long)s; \
89 unsigned long offset = part_offset + offsetof(type, member); \
90 type *p; \
91 int err; \
92 char *kaddr; \
93 unsigned long map_start; \
94 unsigned long map_len; \
95 unsigned long mem_len = sizeof(((type *)0)->member); \
96 if (token && token->kaddr && token->offset <= offset && \
97 token->eb == eb && \
98 (token->offset + PAGE_CACHE_SIZE >= offset + mem_len)) { \
99 kaddr = token->kaddr; \
100 p = (type *)(kaddr + part_offset - token->offset); \
101 p->member = cpu_to_le##bits(val); \
102 return; \
103 } \
104 err = map_private_extent_buffer(eb, offset, \
105 mem_len, \
106 &kaddr, &map_start, &map_len); \
107 if (err) { \
108 __le##bits val2; \
109 val2 = cpu_to_le##bits(val); \
110 write_eb_member(eb, s, type, member, &val2); \
111 return; \
112 } \
113 p = (type *)(kaddr + part_offset - map_start); \
114 p->member = cpu_to_le##bits(val); \
115 if (token) { \
116 token->kaddr = kaddr; \
117 token->offset = map_start; \
118 token->eb = eb; \
119 } \
120 } \
121 void btrfs_set_##name(struct extent_buffer *eb, \
122 type *s, u##bits val) \
123 { \
124 btrfs_set_token_##name(eb, s, val, NULL); \
125 } \
126 u##bits btrfs_##name(struct extent_buffer *eb, \
127 type *s) \
128 { \
129 return btrfs_token_##name(eb, s, NULL); \
130 } \
136 {
140 }