release/src/router/busybox/util-linux/volume_id/bcache.c

   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
  11 //kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_BCACHE) += bcache.o
  12
  13 //config:
  14 //config:config FEATURE_VOLUMEID_BCACHE
  15 //config:       bool "bcache filesystem"
  16 //config:       default y
  17 //config:       depends on VOLUMEID
  18 //config:       help
  19 //config:         TODO
  20 //config:
  21
  22 #include "volume_id_internal.h"
  23
  24 #define SB_LABEL_SIZE      32
  25 #define SB_JOURNAL_BUCKETS 256U
  26
  27 static const char bcache_magic[] ALIGN1 = {
  28         0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
  29         0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81
  30 };
  31
  32 struct bcache_super_block {
  33         uint64_t                csum;
  34         uint64_t                offset; /* sector where this sb was written */
  35         uint64_t                version;
  36
  37         uint8_t                 magic[16];
  38
  39         uint8_t                 uuid[16];
  40         union {
  41                 uint8_t         set_uuid[16];
  42                 uint64_t        set_magic;
  43         };
  44         uint8_t                 label[SB_LABEL_SIZE];
  45
  46         uint64_t                flags;
  47         uint64_t                seq;
  48         uint64_t                pad[8];
  49
  50         union {
  51         struct {
  52                 /* Cache devices */
  53                 uint64_t        nbuckets;       /* device size */
  54
  55                 uint16_t        block_size;     /* sectors */
  56                 uint16_t        bucket_size;    /* sectors */
  57
  58                 uint16_t        nr_in_set;
  59                 uint16_t        nr_this_dev;
  60         };
  61         struct {
  62                 /* Backing devices */
  63                 uint64_t        data_offset;
  64
  65                 /*
  66                  * block_size from the cache device section is still used by
  67                  * backing devices, so don't add anything here until we fix
  68                  * things to not need it for backing devices anymore
  69                  */
  70         };
  71         };
  72
  73         uint32_t                last_mount;     /* time_t */
  74
  75         uint16_t                first_bucket;
  76         union {
  77                 uint16_t        njournal_buckets;
  78                 uint16_t        keys;
  79         };
  80         uint64_t                d[SB_JOURNAL_BUCKETS];  /* journal buckets */
  81 };
  82
  83 /* magic string */
  84 #define BCACHE_SB_MAGIC     bcache_magic
  85 /* magic string len */
  86 #define BCACHE_SB_MAGIC_LEN sizeof (bcache_magic)
  87 /* super block offset */
  88 #define BCACHE_SB_OFF       0x1000
  89 /* supper block offset in kB */
  90 #define BCACHE_SB_KBOFF     (BCACHE_SB_OFF >> 10)
  91 /* magic string offset within super block */
  92 #define BCACHE_SB_MAGIC_OFF offsetof (struct bcache_super_block, magic)
  93
  94 int FAST_FUNC volume_id_probe_bcache(struct volume_id *id /*,uint64_t off*/)
  95 {
  96         struct bcache_super_block *sb;
  97
  98         sb = volume_id_get_buffer(id, BCACHE_SB_OFF, sizeof(*sb));
  99         if (sb == NULL)
 100                 return -1;
 101
 102         if (memcmp(sb->magic, BCACHE_SB_MAGIC, BCACHE_SB_MAGIC_LEN) != 0)
 103                 return -1;
 104
 105         volume_id_set_label_string(id, sb->label, SB_LABEL_SIZE);
 106         volume_id_set_uuid(id, sb->uuid, UUID_DCE);
 107         IF_FEATURE_BLKID_TYPE(id->type = "bcache";)
 108
 109         return 0;
 110 }