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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. | |
39 | */ | |
40 | ||
0f82731f CM |
41 | #define BTRFS_SETGET_FUNCS(name, type, member, bits) \ |
42 | u##bits btrfs_##name(struct extent_buffer *eb, \ | |
43 | type *s) \ | |
44 | { \ | |
df68b8a7 DM |
45 | unsigned long part_offset = (unsigned long)s; \ |
46 | unsigned long offset = part_offset + offsetof(type, member); \ | |
47 | type *p; \ | |
0f82731f CM |
48 | /* ugly, but we want the fast path here */ \ |
49 | if (eb->map_token && offset >= eb->map_start && \ | |
50 | offset + sizeof(((type *)0)->member) <= eb->map_start + \ | |
51 | eb->map_len) { \ | |
df68b8a7 DM |
52 | p = (type *)(eb->kaddr + part_offset - eb->map_start); \ |
53 | return le##bits##_to_cpu(p->member); \ | |
0f82731f CM |
54 | } \ |
55 | { \ | |
56 | int err; \ | |
57 | char *map_token; \ | |
58 | char *kaddr; \ | |
59 | int unmap_on_exit = (eb->map_token == NULL); \ | |
60 | unsigned long map_start; \ | |
61 | unsigned long map_len; \ | |
62 | __le##bits res; \ | |
63 | err = map_extent_buffer(eb, offset, \ | |
64 | sizeof(((type *)0)->member), \ | |
65 | &map_token, &kaddr, \ | |
66 | &map_start, &map_len, KM_USER1); \ | |
67 | if (err) { \ | |
68 | read_eb_member(eb, s, type, member, &res); \ | |
69 | return le##bits##_to_cpu(res); \ | |
70 | } \ | |
df68b8a7 DM |
71 | p = (type *)(kaddr + part_offset - map_start); \ |
72 | res = le##bits##_to_cpu(p->member); \ | |
0f82731f CM |
73 | if (unmap_on_exit) \ |
74 | unmap_extent_buffer(eb, map_token, KM_USER1); \ | |
75 | return res; \ | |
76 | } \ | |
77 | } \ | |
78 | void btrfs_set_##name(struct extent_buffer *eb, \ | |
79 | type *s, u##bits val) \ | |
80 | { \ | |
df68b8a7 DM |
81 | unsigned long part_offset = (unsigned long)s; \ |
82 | unsigned long offset = part_offset + offsetof(type, member); \ | |
83 | type *p; \ | |
0f82731f CM |
84 | /* ugly, but we want the fast path here */ \ |
85 | if (eb->map_token && offset >= eb->map_start && \ | |
86 | offset + sizeof(((type *)0)->member) <= eb->map_start + \ | |
87 | eb->map_len) { \ | |
df68b8a7 DM |
88 | p = (type *)(eb->kaddr + part_offset - eb->map_start); \ |
89 | p->member = cpu_to_le##bits(val); \ | |
0f82731f CM |
90 | return; \ |
91 | } \ | |
92 | { \ | |
93 | int err; \ | |
94 | char *map_token; \ | |
95 | char *kaddr; \ | |
96 | int unmap_on_exit = (eb->map_token == NULL); \ | |
97 | unsigned long map_start; \ | |
98 | unsigned long map_len; \ | |
99 | err = map_extent_buffer(eb, offset, \ | |
100 | sizeof(((type *)0)->member), \ | |
101 | &map_token, &kaddr, \ | |
102 | &map_start, &map_len, KM_USER1); \ | |
103 | if (err) { \ | |
104 | val = cpu_to_le##bits(val); \ | |
105 | write_eb_member(eb, s, type, member, &val); \ | |
106 | return; \ | |
107 | } \ | |
df68b8a7 DM |
108 | p = (type *)(kaddr + part_offset - map_start); \ |
109 | p->member = cpu_to_le##bits(val); \ | |
0f82731f CM |
110 | if (unmap_on_exit) \ |
111 | unmap_extent_buffer(eb, map_token, KM_USER1); \ | |
112 | } \ | |
113 | } | |
114 | ||
115 | #include "ctree.h" | |
116 | ||
e644d021 CM |
117 | void btrfs_node_key(struct extent_buffer *eb, |
118 | struct btrfs_disk_key *disk_key, int nr) | |
119 | { | |
120 | unsigned long ptr = btrfs_node_key_ptr_offset(nr); | |
121 | if (eb->map_token && ptr >= eb->map_start && | |
122 | ptr + sizeof(*disk_key) <= eb->map_start + eb->map_len) { | |
123 | memcpy(disk_key, eb->kaddr + ptr - eb->map_start, | |
124 | sizeof(*disk_key)); | |
125 | return; | |
126 | } else if (eb->map_token) { | |
127 | unmap_extent_buffer(eb, eb->map_token, KM_USER1); | |
128 | eb->map_token = NULL; | |
129 | } | |
130 | read_eb_member(eb, (struct btrfs_key_ptr *)ptr, | |
131 | struct btrfs_key_ptr, key, disk_key); | |
132 | } |