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136 lines
2.9 KiB
C
136 lines
2.9 KiB
C
/*
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* Copyright (C) 2004 Luca Berra
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* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v.2.1.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "lib.h"
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#include "metadata.h"
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#include "xlate.h"
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#ifdef linux
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/* Lifted from <linux/raid/md_p.h> because of difficulty including it */
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#define MD_SB_MAGIC 0xa92b4efc
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#define MD_RESERVED_BYTES (64 * 1024ULL)
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#define MD_RESERVED_SECTORS (MD_RESERVED_BYTES / 512)
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#define MD_NEW_SIZE_SECTORS(x) ((x & ~(MD_RESERVED_SECTORS - 1)) \
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- MD_RESERVED_SECTORS)
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static int _dev_has_md_magic(struct device *dev, uint64_t sb_offset)
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{
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uint32_t md_magic;
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/* Version 1 is little endian; version 0.90.0 is machine endian */
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if (dev_read(dev, sb_offset, sizeof(uint32_t), &md_magic) &&
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((md_magic == xlate32(MD_SB_MAGIC)) ||
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(md_magic == MD_SB_MAGIC)))
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return 1;
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return 0;
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}
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/*
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* Calculate the position of the superblock.
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* It is always aligned to a 4K boundary and
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* depending on minor_version, it can be:
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* 0: At least 8K, but less than 12K, from end of device
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* 1: At start of device
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* 2: 4K from start of device.
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*/
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typedef enum {
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MD_MINOR_VERSION_MIN,
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MD_MINOR_V0 = MD_MINOR_VERSION_MIN,
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MD_MINOR_V1,
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MD_MINOR_V2,
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MD_MINOR_VERSION_MAX = MD_MINOR_V2
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} md_minor_version_t;
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static uint64_t _v1_sb_offset(uint64_t size, md_minor_version_t minor_version)
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{
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uint64_t uninitialized_var(sb_offset);
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switch(minor_version) {
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case MD_MINOR_V0:
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sb_offset = (size - 8 * 2) & ~(4 * 2 - 1ULL);
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break;
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case MD_MINOR_V1:
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sb_offset = 0;
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break;
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case MD_MINOR_V2:
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sb_offset = 4 * 2;
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break;
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}
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sb_offset <<= SECTOR_SHIFT;
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return sb_offset;
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}
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/*
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* Returns -1 on error
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*/
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int dev_is_md(struct device *dev, uint64_t *sb)
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{
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int ret = 1;
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md_minor_version_t minor;
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uint64_t size, sb_offset;
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if (!dev_get_size(dev, &size)) {
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stack;
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return -1;
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}
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if (size < MD_RESERVED_SECTORS * 2)
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return 0;
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if (!dev_open(dev)) {
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stack;
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return -1;
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}
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/* Check if it is an md component device. */
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/* Version 0.90.0 */
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sb_offset = MD_NEW_SIZE_SECTORS(size) << SECTOR_SHIFT;
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if (_dev_has_md_magic(dev, sb_offset))
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goto out;
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minor = MD_MINOR_VERSION_MIN;
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/* Version 1, try v1.0 -> v1.2 */
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do {
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sb_offset = _v1_sb_offset(size, minor);
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if (_dev_has_md_magic(dev, sb_offset))
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goto out;
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} while (++minor <= MD_MINOR_VERSION_MAX);
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ret = 0;
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out:
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if (!dev_close(dev))
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stack;
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if (ret && sb)
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*sb = sb_offset;
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return ret;
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}
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#else
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int dev_is_md(struct device *dev __attribute((unused)),
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uint64_t *sb __attribute((unused)))
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{
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return 0;
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}
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#endif
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