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c1d7c514 | 1 | // SPDX-License-Identifier: GPL-2.0 |
0f82731f CM |
2 | /* |
3 | * Copyright (C) 2007 Oracle. All rights reserved. | |
0f82731f CM |
4 | */ |
5 | ||
6 | #include <linux/highmem.h> | |
18077bb4 | 7 | #include <asm/unaligned.h> |
d352ac68 | 8 | |
18077bb4 LZ |
9 | #include "ctree.h" |
10 | ||
11 | static inline u8 get_unaligned_le8(const void *p) | |
12 | { | |
13 | return *(u8 *)p; | |
14 | } | |
15 | ||
16 | static inline void put_unaligned_le8(u8 val, void *p) | |
17 | { | |
18 | *(u8 *)p = val; | |
19 | } | |
20 | ||
21 | /* | |
22 | * this is some deeply nasty code. | |
d352ac68 CM |
23 | * |
24 | * The end result is that anyone who #includes ctree.h gets a | |
18077bb4 | 25 | * declaration for the btrfs_set_foo functions and btrfs_foo functions, |
01327610 | 26 | * which are wrappers of btrfs_set_token_#bits functions and |
18077bb4 | 27 | * btrfs_get_token_#bits functions, which are defined in this file. |
d352ac68 CM |
28 | * |
29 | * These setget functions do all the extent_buffer related mapping | |
30 | * required to efficiently read and write specific fields in the extent | |
31 | * buffers. Every pointer to metadata items in btrfs is really just | |
32 | * an unsigned long offset into the extent buffer which has been | |
33 | * cast to a specific type. This gives us all the gcc type checking. | |
34 | * | |
18077bb4 LZ |
35 | * The extent buffer api is used to do the page spanning work required to |
36 | * have a metadata blocksize different from the page size. | |
d352ac68 CM |
37 | */ |
38 | ||
18077bb4 | 39 | #define DEFINE_BTRFS_SETGET_BITS(bits) \ |
1cbb1f45 JM |
40 | u##bits btrfs_get_token_##bits(const struct extent_buffer *eb, \ |
41 | const void *ptr, unsigned long off, \ | |
18077bb4 | 42 | struct btrfs_map_token *token) \ |
0f82731f | 43 | { \ |
18077bb4 LZ |
44 | unsigned long part_offset = (unsigned long)ptr; \ |
45 | unsigned long offset = part_offset + off; \ | |
46 | void *p; \ | |
47 | int err; \ | |
48 | char *kaddr; \ | |
49 | unsigned long map_start; \ | |
50 | unsigned long map_len; \ | |
51 | int size = sizeof(u##bits); \ | |
52 | u##bits res; \ | |
53 | \ | |
54 | if (token && token->kaddr && token->offset <= offset && \ | |
55 | token->eb == eb && \ | |
ea1754a0 | 56 | (token->offset + PAGE_SIZE >= offset + size)) { \ |
18077bb4 LZ |
57 | kaddr = token->kaddr; \ |
58 | p = kaddr + part_offset - token->offset; \ | |
59 | res = get_unaligned_le##bits(p + off); \ | |
60 | return res; \ | |
61 | } \ | |
62 | err = map_private_extent_buffer(eb, offset, size, \ | |
63 | &kaddr, &map_start, &map_len); \ | |
64 | if (err) { \ | |
65 | __le##bits leres; \ | |
66 | \ | |
67 | read_extent_buffer(eb, &leres, offset, size); \ | |
68 | return le##bits##_to_cpu(leres); \ | |
69 | } \ | |
70 | p = kaddr + part_offset - map_start; \ | |
71 | res = get_unaligned_le##bits(p + off); \ | |
72 | if (token) { \ | |
73 | token->kaddr = kaddr; \ | |
74 | token->offset = map_start; \ | |
75 | token->eb = eb; \ | |
76 | } \ | |
77 | return res; \ | |
0f82731f | 78 | } \ |
18077bb4 | 79 | void btrfs_set_token_##bits(struct extent_buffer *eb, \ |
1cbb1f45 JM |
80 | const void *ptr, unsigned long off, \ |
81 | u##bits val, \ | |
18077bb4 | 82 | struct btrfs_map_token *token) \ |
0f82731f | 83 | { \ |
18077bb4 LZ |
84 | unsigned long part_offset = (unsigned long)ptr; \ |
85 | unsigned long offset = part_offset + off; \ | |
86 | void *p; \ | |
87 | int err; \ | |
88 | char *kaddr; \ | |
89 | unsigned long map_start; \ | |
90 | unsigned long map_len; \ | |
91 | int size = sizeof(u##bits); \ | |
92 | \ | |
93 | if (token && token->kaddr && token->offset <= offset && \ | |
94 | token->eb == eb && \ | |
ea1754a0 | 95 | (token->offset + PAGE_SIZE >= offset + size)) { \ |
18077bb4 LZ |
96 | kaddr = token->kaddr; \ |
97 | p = kaddr + part_offset - token->offset; \ | |
98 | put_unaligned_le##bits(val, p + off); \ | |
99 | return; \ | |
100 | } \ | |
101 | err = map_private_extent_buffer(eb, offset, size, \ | |
102 | &kaddr, &map_start, &map_len); \ | |
103 | if (err) { \ | |
104 | __le##bits val2; \ | |
105 | \ | |
106 | val2 = cpu_to_le##bits(val); \ | |
107 | write_extent_buffer(eb, &val2, offset, size); \ | |
108 | return; \ | |
109 | } \ | |
110 | p = kaddr + part_offset - map_start; \ | |
111 | put_unaligned_le##bits(val, p + off); \ | |
112 | if (token) { \ | |
113 | token->kaddr = kaddr; \ | |
114 | token->offset = map_start; \ | |
115 | token->eb = eb; \ | |
116 | } \ | |
117 | } | |
0f82731f | 118 | |
18077bb4 LZ |
119 | DEFINE_BTRFS_SETGET_BITS(8) |
120 | DEFINE_BTRFS_SETGET_BITS(16) | |
121 | DEFINE_BTRFS_SETGET_BITS(32) | |
122 | DEFINE_BTRFS_SETGET_BITS(64) | |
0f82731f | 123 | |
1cbb1f45 | 124 | void btrfs_node_key(const struct extent_buffer *eb, |
e644d021 CM |
125 | struct btrfs_disk_key *disk_key, int nr) |
126 | { | |
127 | unsigned long ptr = btrfs_node_key_ptr_offset(nr); | |
e644d021 CM |
128 | read_eb_member(eb, (struct btrfs_key_ptr *)ptr, |
129 | struct btrfs_key_ptr, key, disk_key); | |
130 | } |