[2725] | 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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[3232] | 105 | IF_FEATURE_BLKID_TYPE(id->type = "btrfs";)
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[2725] | 106 |
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| 107 | return 0;
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| 108 | }
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