LXR busybox/util-linux/volume

   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
  22static 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
  27struct 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
  89int 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