1 /*
2 * Copyright (C) 2013 Rolf Fokkens <rolf@fokkens.nl>
3 *
4 * This file may be redistributed under the terms of the
5 * GNU Lesser General Public License.
6 *
7 * Based on code fragments from bcache-tools by Kent Overstreet:
8 * http://evilpiepirate.org/git/bcache-tools.git
9 */
10 //config:config FEATURE_VOLUMEID_BCACHE
11 //config: bool "bcache filesystem"
12 //config: default y
13 //config: depends on VOLUMEID
14
15 //kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_BCACHE) += bcache.o
16
17 #include "volume_id_internal.h"
18
19 #define SB_LABEL_SIZE 32
20 #define SB_JOURNAL_BUCKETS 256U
21
22 static const char bcache_magic[] ALIGN1 = {
23 0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
24 0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81
25 };
26
27 struct bcache_super_block {
28 uint64_t csum;
29 uint64_t offset; /* sector where this sb was written */
30 uint64_t version;
31
32 uint8_t magic[16];
33
34 uint8_t uuid[16];
35 union {
36 uint8_t set_uuid[16];
37 uint64_t set_magic;
38 };
39 uint8_t label[SB_LABEL_SIZE];
40
41 uint64_t flags;
42 uint64_t seq;
43 uint64_t pad[8];
44
45 union {
46 struct {
47 /* Cache devices */
48 uint64_t nbuckets; /* device size */
49
50 uint16_t block_size; /* sectors */
51 uint16_t bucket_size; /* sectors */
52
53 uint16_t nr_in_set;
54 uint16_t nr_this_dev;
55 };
56 struct {
57 /* Backing devices */
58 uint64_t data_offset;
59
60 /*
61 * block_size from the cache device section is still used by
62 * backing devices, so don't add anything here until we fix
63 * things to not need it for backing devices anymore
64 */
65 };
66 };
67
68 uint32_t last_mount; /* time_t */
69
70 uint16_t first_bucket;
71 union {
72 uint16_t njournal_buckets;
73 uint16_t keys;
74 };
75 uint64_t d[SB_JOURNAL_BUCKETS]; /* journal buckets */
76 };
77
78 /* magic string */
79 #define BCACHE_SB_MAGIC bcache_magic
80 /* magic string len */
81 #define BCACHE_SB_MAGIC_LEN sizeof (bcache_magic)
82 /* super block offset */
83 #define BCACHE_SB_OFF 0x1000
84 /* supper block offset in kB */
85 #define BCACHE_SB_KBOFF (BCACHE_SB_OFF >> 10)
86 /* magic string offset within super block */
87 #define BCACHE_SB_MAGIC_OFF offsetof (struct bcache_super_block, magic)
88
volume_id_probe_bcache(struct volume_id * id)89 int FAST_FUNC volume_id_probe_bcache(struct volume_id *id /*,uint64_t off*/)
90 {
91 struct bcache_super_block *sb;
92
93 sb = volume_id_get_buffer(id, BCACHE_SB_OFF, sizeof(*sb));
94 if (sb == NULL)
95 return -1;
96
97 if (memcmp(sb->magic, BCACHE_SB_MAGIC, BCACHE_SB_MAGIC_LEN) != 0)
98 return -1;
99
100 volume_id_set_label_string(id, sb->label, SB_LABEL_SIZE);
101 volume_id_set_uuid(id, sb->uuid, UUID_DCE);
102 IF_FEATURE_BLKID_TYPE(id->type = "bcache";)
103
104 return 0;
105 }
106