/* * Copyright (C) 2004 Luca Berra * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved. * * This file is part of LVM2. * * This copyrighted material is made available to anyone wishing to use, * modify, copy, or redistribute it subject to the terms and conditions * of the GNU Lesser General Public License v.2.1. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include "lib.h" #include "metadata.h" #include "xlate.h" #ifdef linux /* Lifted from because of difficulty including it */ #define MD_SB_MAGIC 0xa92b4efc #define MD_RESERVED_BYTES (64 * 1024ULL) #define MD_RESERVED_SECTORS (MD_RESERVED_BYTES / 512) #define MD_NEW_SIZE_SECTORS(x) ((x & ~(MD_RESERVED_SECTORS - 1)) \ - MD_RESERVED_SECTORS) static int _dev_has_md_magic(struct device *dev, uint64_t sb_offset) { uint32_t md_magic; /* Version 1 is little endian; version 0.90.0 is machine endian */ if (dev_read(dev, sb_offset, sizeof(uint32_t), &md_magic) && ((md_magic == xlate32(MD_SB_MAGIC)) || (md_magic == MD_SB_MAGIC))) return 1; return 0; } /* * Calculate the position of the superblock. * It is always aligned to a 4K boundary and * depending on minor_version, it can be: * 0: At least 8K, but less than 12K, from end of device * 1: At start of device * 2: 4K from start of device. */ static uint64_t _v1_sb_offset(uint64_t size, unsigned minor_version) { uint64_t sb_offset; switch(minor_version) { case 0: sb_offset = (size - 8 * 2) & ~(4 * 2 - 1ULL); break; case 1: sb_offset = 0; break; case 2: sb_offset = 4 * 2; break; } sb_offset <<= SECTOR_SHIFT; return sb_offset; } /* * Returns -1 on error */ int dev_is_md(struct device *dev, uint64_t *sb) { int ret = 1; unsigned minor = 0; uint64_t size, sb_offset; if (!dev_get_size(dev, &size)) { stack; return -1; } if (size < MD_RESERVED_SECTORS * 2) return 0; if (!dev_open(dev)) { stack; return -1; } /* Check if it is an md component device. */ /* Version 0.90.0 */ sb_offset = MD_NEW_SIZE_SECTORS(size) << SECTOR_SHIFT; if (_dev_has_md_magic(dev, sb_offset)) goto out; /* Version 1, try v1.0 -> v1.2 */ do { sb_offset = _v1_sb_offset(size, minor); if (_dev_has_md_magic(dev, sb_offset)) goto out; } while (++minor <= 2); ret = 0; out: if (!dev_close(dev)) stack; if (ret && sb) *sb = sb_offset; return ret; } #else int dev_is_md(struct device *dev __attribute((unused)), uint64_t *sb __attribute((unused))) { return 0; } #endif