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