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Signed-off-by: Sven-Göran Bergh <svengbergh-busybox@yahoo.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
/*
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* volume_id - reads filesystem label and uuid
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*
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* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
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* Copyright (C) 2009 Vladimir Dronnikov <dronnikov@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "volume_id_internal.h"
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#define BTRFS_UUID_SIZE 16
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#define BTRFS_LABEL_SIZE 256
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#define BTRFS_CSUM_SIZE 32
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#define BTRFS_FSID_SIZE 16
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#define BTRFS_MAGIC "_BHRfS_M"
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struct btrfs_dev_item {
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uint64_t devid;
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uint64_t total_bytes;
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uint64_t bytes_used;
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uint32_t io_align;
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uint32_t io_width;
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uint32_t sector_size;
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uint64_t type;
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uint64_t generation;
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uint64_t start_offset;
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uint32_t dev_group;
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uint8_t seek_speed;
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uint8_t bandwidth;
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uint8_t uuid[BTRFS_UUID_SIZE];
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uint8_t fsid[BTRFS_UUID_SIZE];
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} PACKED;
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struct btrfs_super_block {
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uint8_t csum[BTRFS_CSUM_SIZE];
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uint8_t fsid[BTRFS_FSID_SIZE]; // UUID
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uint64_t bytenr;
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uint64_t flags;
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uint8_t magic[8];
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uint64_t generation;
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uint64_t root;
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uint64_t chunk_root;
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uint64_t log_root;
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uint64_t log_root_transid;
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uint64_t total_bytes;
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uint64_t bytes_used;
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uint64_t root_dir_objectid;
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uint64_t num_devices;
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uint32_t sectorsize;
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uint32_t nodesize;
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uint32_t leafsize;
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uint32_t stripesize;
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uint32_t sys_chunk_array_size;
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uint64_t chunk_root_generation;
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uint64_t compat_flags;
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uint64_t compat_ro_flags;
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uint64_t incompat_flags;
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uint16_t csum_type;
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uint8_t root_level;
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uint8_t chunk_root_level;
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uint8_t log_root_level;
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struct btrfs_dev_item dev_item;
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uint8_t label[BTRFS_LABEL_SIZE]; // LABEL
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// ...
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} PACKED;
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int FAST_FUNC volume_id_probe_btrfs(struct volume_id *id /*,uint64_t off*/)
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{
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// btrfs has superblocks at 64K, 64M and 256G
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// minimum btrfs size is 256M
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// so we never step out the device if we analyze
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// the first and the second superblocks
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struct btrfs_super_block *sb;
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unsigned off = 64;
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while (off < 64*1024*1024) {
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off *= 1024;
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dbg("btrfs: probing at offset 0x%x", off);
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sb = volume_id_get_buffer(id, off, sizeof(*sb));
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if (sb == NULL)
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return -1;
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if (memcmp(sb->magic, BTRFS_MAGIC, 8) != 0)
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return -1;
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}
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// N.B.: btrfs natively supports 256 (>VOLUME_ID_LABEL_SIZE) size labels
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volume_id_set_label_string(id, sb->label, VOLUME_ID_LABEL_SIZE);
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volume_id_set_uuid(id, sb->fsid, UUID_DCE);
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IF_FEATURE_BLKID_TYPE(id->type = "btrfs";)
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return 0;
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}
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