1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
/*
* volume_id - reads filesystem label and uuid
*
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2009 Vladimir Dronnikov <dronnikov@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "volume_id_internal.h"
#define BTRFS_UUID_SIZE 16
#define BTRFS_LABEL_SIZE 256
#define BTRFS_CSUM_SIZE 32
#define BTRFS_FSID_SIZE 16
#define BTRFS_MAGIC "_BHRfS_M"
struct btrfs_dev_item {
uint64_t devid;
uint64_t total_bytes;
uint64_t bytes_used;
uint32_t io_align;
uint32_t io_width;
uint32_t sector_size;
uint64_t type;
uint64_t generation;
uint64_t start_offset;
uint32_t dev_group;
uint8_t seek_speed;
uint8_t bandwidth;
uint8_t uuid[BTRFS_UUID_SIZE];
uint8_t fsid[BTRFS_UUID_SIZE];
} PACKED;
struct btrfs_super_block {
uint8_t csum[BTRFS_CSUM_SIZE];
uint8_t fsid[BTRFS_FSID_SIZE]; // UUID
uint64_t bytenr;
uint64_t flags;
uint8_t magic[8];
uint64_t generation;
uint64_t root;
uint64_t chunk_root;
uint64_t log_root;
uint64_t log_root_transid;
uint64_t total_bytes;
uint64_t bytes_used;
uint64_t root_dir_objectid;
uint64_t num_devices;
uint32_t sectorsize;
uint32_t nodesize;
uint32_t leafsize;
uint32_t stripesize;
uint32_t sys_chunk_array_size;
uint64_t chunk_root_generation;
uint64_t compat_flags;
uint64_t compat_ro_flags;
uint64_t incompat_flags;
uint16_t csum_type;
uint8_t root_level;
uint8_t chunk_root_level;
uint8_t log_root_level;
struct btrfs_dev_item dev_item;
uint8_t label[BTRFS_LABEL_SIZE]; // LABEL
// ...
} PACKED;
int FAST_FUNC volume_id_probe_btrfs(struct volume_id *id /*,uint64_t off*/)
{
// btrfs has superblocks at 64K, 64M and 256G
// minimum btrfs size is 256M
// so we never step out the device if we analyze
// the first and the second superblocks
struct btrfs_super_block *sb;
unsigned off = 64;
while (off < 64*1024*1024) {
off *= 1024;
dbg("btrfs: probing at offset 0x%x", off);
sb = volume_id_get_buffer(id, off, sizeof(*sb));
if (sb == NULL)
return -1;
if (memcmp(sb->magic, BTRFS_MAGIC, 8) != 0)
return -1;
}
// N.B.: btrfs natively supports 256 (>VOLUME_ID_LABEL_SIZE) size labels
volume_id_set_label_string(id, sb->label, VOLUME_ID_LABEL_SIZE);
volume_id_set_uuid(id, sb->fsid, UUID_DCE);
return 0;
}
|
