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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 : : #include <asm/unaligned.h>
21 : :
22 : : #include "ctree.h"
23 : :
24 : : static inline u8 get_unaligned_le8(const void *p)
25 : : {
26 : 0 : return *(u8 *)p;
27 : : }
28 : :
29 : : static inline void put_unaligned_le8(u8 val, void *p)
30 : : {
31 : 0 : *(u8 *)p = val;
32 : : }
33 : :
34 : : /*
35 : : * this is some deeply nasty code.
36 : : *
37 : : * The end result is that anyone who #includes ctree.h gets a
38 : : * declaration for the btrfs_set_foo functions and btrfs_foo functions,
39 : : * which are wappers of btrfs_set_token_#bits functions and
40 : : * btrfs_get_token_#bits functions, which are defined in this file.
41 : : *
42 : : * These setget functions do all the extent_buffer related mapping
43 : : * required to efficiently read and write specific fields in the extent
44 : : * buffers. Every pointer to metadata items in btrfs is really just
45 : : * an unsigned long offset into the extent buffer which has been
46 : : * cast to a specific type. This gives us all the gcc type checking.
47 : : *
48 : : * The extent buffer api is used to do the page spanning work required to
49 : : * have a metadata blocksize different from the page size.
50 : : */
51 : :
52 : : #define DEFINE_BTRFS_SETGET_BITS(bits) \
53 : : u##bits btrfs_get_token_##bits(struct extent_buffer *eb, void *ptr, \
54 : : unsigned long off, \
55 : : struct btrfs_map_token *token) \
56 : : { \
57 : : unsigned long part_offset = (unsigned long)ptr; \
58 : : unsigned long offset = part_offset + off; \
59 : : void *p; \
60 : : int err; \
61 : : char *kaddr; \
62 : : unsigned long map_start; \
63 : : unsigned long map_len; \
64 : : int size = sizeof(u##bits); \
65 : : u##bits res; \
66 : : \
67 : : if (token && token->kaddr && token->offset <= offset && \
68 : : token->eb == eb && \
69 : : (token->offset + PAGE_CACHE_SIZE >= offset + size)) { \
70 : : kaddr = token->kaddr; \
71 : : p = kaddr + part_offset - token->offset; \
72 : : res = get_unaligned_le##bits(p + off); \
73 : : return res; \
74 : : } \
75 : : err = map_private_extent_buffer(eb, offset, size, \
76 : : &kaddr, &map_start, &map_len); \
77 : : if (err) { \
78 : : __le##bits leres; \
79 : : \
80 : : read_extent_buffer(eb, &leres, offset, size); \
81 : : return le##bits##_to_cpu(leres); \
82 : : } \
83 : : p = kaddr + part_offset - map_start; \
84 : : res = get_unaligned_le##bits(p + off); \
85 : : if (token) { \
86 : : token->kaddr = kaddr; \
87 : : token->offset = map_start; \
88 : : token->eb = eb; \
89 : : } \
90 : : return res; \
91 : : } \
92 : : void btrfs_set_token_##bits(struct extent_buffer *eb, \
93 : : void *ptr, unsigned long off, u##bits val, \
94 : : struct btrfs_map_token *token) \
95 : : { \
96 : : unsigned long part_offset = (unsigned long)ptr; \
97 : : unsigned long offset = part_offset + off; \
98 : : void *p; \
99 : : int err; \
100 : : char *kaddr; \
101 : : unsigned long map_start; \
102 : : unsigned long map_len; \
103 : : int size = sizeof(u##bits); \
104 : : \
105 : : if (token && token->kaddr && token->offset <= offset && \
106 : : token->eb == eb && \
107 : : (token->offset + PAGE_CACHE_SIZE >= offset + size)) { \
108 : : kaddr = token->kaddr; \
109 : : p = kaddr + part_offset - token->offset; \
110 : : put_unaligned_le##bits(val, p + off); \
111 : : return; \
112 : : } \
113 : : err = map_private_extent_buffer(eb, offset, size, \
114 : : &kaddr, &map_start, &map_len); \
115 : : if (err) { \
116 : : __le##bits val2; \
117 : : \
118 : : val2 = cpu_to_le##bits(val); \
119 : : write_extent_buffer(eb, &val2, offset, size); \
120 : : return; \
121 : : } \
122 : : p = kaddr + part_offset - map_start; \
123 : : put_unaligned_le##bits(val, p + off); \
124 : : if (token) { \
125 : : token->kaddr = kaddr; \
126 : : token->offset = map_start; \
127 : : token->eb = eb; \
128 : : } \
129 : : }
130 : :
131 [ # # ][ # # ]: 0 : DEFINE_BTRFS_SETGET_BITS(8)
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
132 [ # # ][ # # ]: 0 : DEFINE_BTRFS_SETGET_BITS(16)
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
133 [ # # ][ # # ]: 0 : DEFINE_BTRFS_SETGET_BITS(32)
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
134 [ # # ][ # # ]: 0 : DEFINE_BTRFS_SETGET_BITS(64)
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
135 : :
136 : 0 : void btrfs_node_key(struct extent_buffer *eb,
137 : : struct btrfs_disk_key *disk_key, int nr)
138 : : {
139 : : unsigned long ptr = btrfs_node_key_ptr_offset(nr);
140 : 0 : read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
141 : : struct btrfs_key_ptr, key, disk_key);
142 : 0 : }
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