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0f82731f CM |
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> | |
d352ac68 CM |
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. | |
c99e905c CM |
39 | * |
40 | * The macro starts with a simple function prototype declaration so that | |
41 | * sparse won't complain about it being static. | |
d352ac68 CM |
42 | */ |
43 | ||
0f82731f | 44 | #define BTRFS_SETGET_FUNCS(name, type, member, bits) \ |
c99e905c CM |
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); \ | |
0f82731f CM |
47 | u##bits btrfs_##name(struct extent_buffer *eb, \ |
48 | type *s) \ | |
49 | { \ | |
df68b8a7 DM |
50 | unsigned long part_offset = (unsigned long)s; \ |
51 | unsigned long offset = part_offset + offsetof(type, member); \ | |
52 | type *p; \ | |
0f82731f CM |
53 | /* ugly, but we want the fast path here */ \ |
54 | if (eb->map_token && offset >= eb->map_start && \ | |
55 | offset + sizeof(((type *)0)->member) <= eb->map_start + \ | |
56 | eb->map_len) { \ | |
df68b8a7 DM |
57 | p = (type *)(eb->kaddr + part_offset - eb->map_start); \ |
58 | return le##bits##_to_cpu(p->member); \ | |
0f82731f CM |
59 | } \ |
60 | { \ | |
61 | int err; \ | |
62 | char *map_token; \ | |
63 | char *kaddr; \ | |
64 | int unmap_on_exit = (eb->map_token == NULL); \ | |
65 | unsigned long map_start; \ | |
66 | unsigned long map_len; \ | |
c99e905c | 67 | u##bits res; \ |
0f82731f | 68 | err = map_extent_buffer(eb, offset, \ |
d397712b | 69 | sizeof(((type *)0)->member), \ |
0f82731f CM |
70 | &map_token, &kaddr, \ |
71 | &map_start, &map_len, KM_USER1); \ | |
72 | if (err) { \ | |
c99e905c CM |
73 | __le##bits leres; \ |
74 | read_eb_member(eb, s, type, member, &leres); \ | |
75 | return le##bits##_to_cpu(leres); \ | |
0f82731f | 76 | } \ |
df68b8a7 DM |
77 | p = (type *)(kaddr + part_offset - map_start); \ |
78 | res = le##bits##_to_cpu(p->member); \ | |
0f82731f CM |
79 | if (unmap_on_exit) \ |
80 | unmap_extent_buffer(eb, map_token, KM_USER1); \ | |
81 | return res; \ | |
82 | } \ | |
83 | } \ | |
84 | void btrfs_set_##name(struct extent_buffer *eb, \ | |
85 | type *s, u##bits val) \ | |
86 | { \ | |
df68b8a7 DM |
87 | unsigned long part_offset = (unsigned long)s; \ |
88 | unsigned long offset = part_offset + offsetof(type, member); \ | |
89 | type *p; \ | |
0f82731f CM |
90 | /* ugly, but we want the fast path here */ \ |
91 | if (eb->map_token && offset >= eb->map_start && \ | |
92 | offset + sizeof(((type *)0)->member) <= eb->map_start + \ | |
93 | eb->map_len) { \ | |
df68b8a7 DM |
94 | p = (type *)(eb->kaddr + part_offset - eb->map_start); \ |
95 | p->member = cpu_to_le##bits(val); \ | |
0f82731f CM |
96 | return; \ |
97 | } \ | |
98 | { \ | |
99 | int err; \ | |
100 | char *map_token; \ | |
101 | char *kaddr; \ | |
102 | int unmap_on_exit = (eb->map_token == NULL); \ | |
103 | unsigned long map_start; \ | |
104 | unsigned long map_len; \ | |
105 | err = map_extent_buffer(eb, offset, \ | |
d397712b | 106 | sizeof(((type *)0)->member), \ |
0f82731f CM |
107 | &map_token, &kaddr, \ |
108 | &map_start, &map_len, KM_USER1); \ | |
109 | if (err) { \ | |
c99e905c CM |
110 | __le##bits val2; \ |
111 | val2 = cpu_to_le##bits(val); \ | |
112 | write_eb_member(eb, s, type, member, &val2); \ | |
0f82731f CM |
113 | return; \ |
114 | } \ | |
df68b8a7 DM |
115 | p = (type *)(kaddr + part_offset - map_start); \ |
116 | p->member = cpu_to_le##bits(val); \ | |
0f82731f CM |
117 | if (unmap_on_exit) \ |
118 | unmap_extent_buffer(eb, map_token, KM_USER1); \ | |
119 | } \ | |
120 | } | |
121 | ||
122 | #include "ctree.h" | |
123 | ||
e644d021 CM |
124 | void btrfs_node_key(struct extent_buffer *eb, |
125 | struct btrfs_disk_key *disk_key, int nr) | |
126 | { | |
127 | unsigned long ptr = btrfs_node_key_ptr_offset(nr); | |
128 | if (eb->map_token && ptr >= eb->map_start && | |
129 | ptr + sizeof(*disk_key) <= eb->map_start + eb->map_len) { | |
130 | memcpy(disk_key, eb->kaddr + ptr - eb->map_start, | |
131 | sizeof(*disk_key)); | |
132 | return; | |
133 | } else if (eb->map_token) { | |
134 | unmap_extent_buffer(eb, eb->map_token, KM_USER1); | |
135 | eb->map_token = NULL; | |
136 | } | |
137 | read_eb_member(eb, (struct btrfs_key_ptr *)ptr, | |
138 | struct btrfs_key_ptr, key, disk_key); | |
139 | } |