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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 3661589 : return *(u8 *)p;
27 : }
28 :
29 : static inline void put_unaligned_le8(u8 val, void *p)
30 : {
31 408497 : *(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 8534272 : DEFINE_BTRFS_SETGET_BITS(8)
132 3062988 : DEFINE_BTRFS_SETGET_BITS(16)
133 95799120 : DEFINE_BTRFS_SETGET_BITS(32)
134 33053371 : DEFINE_BTRFS_SETGET_BITS(64)
135 :
136 1247331 : 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 1247331 : read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
141 : struct btrfs_key_ptr, key, disk_key);
142 1248596 : }
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