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