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lvm2/lib/device/dev-md.c
2008-10-03 14:22:18 +00:00

199 lines
4.3 KiB
C

/*
* Copyright (C) 2004 Luca Berra
* Copyright (C) 2004-2008 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"
#include "filter.h"
#ifdef linux
/* Lifted from <linux/raid/md_p.h> 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.
*/
typedef enum {
MD_MINOR_VERSION_MIN,
MD_MINOR_V0 = MD_MINOR_VERSION_MIN,
MD_MINOR_V1,
MD_MINOR_V2,
MD_MINOR_VERSION_MAX = MD_MINOR_V2
} md_minor_version_t;
static uint64_t _v1_sb_offset(uint64_t size, md_minor_version_t minor_version)
{
uint64_t uninitialized_var(sb_offset);
switch(minor_version) {
case MD_MINOR_V0:
sb_offset = (size - 8 * 2) & ~(4 * 2 - 1ULL);
break;
case MD_MINOR_V1:
sb_offset = 0;
break;
case MD_MINOR_V2:
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;
md_minor_version_t minor;
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;
minor = MD_MINOR_VERSION_MIN;
/* 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 <= MD_MINOR_VERSION_MAX);
ret = 0;
out:
if (!dev_close(dev))
stack;
if (ret && sb)
*sb = sb_offset;
return ret;
}
/*
* Retrieve chunk size from md device using sysfs.
*/
unsigned long dev_md_chunk_size(const char *sysfs_dir, struct device *dev)
{
char path[PATH_MAX+1], buffer[64];
FILE *fp;
struct stat info;
unsigned long chunk_size_bytes = 0UL;
if (MAJOR(dev->dev) != md_major())
return 0;
if (!sysfs_dir || !*sysfs_dir)
return_0;
if (dm_snprintf(path, PATH_MAX, "%s/dev/block/%d:%d/md/chunk_size",
sysfs_dir, MAJOR(dev->dev), MINOR(dev->dev)) < 0) {
log_error("dm_snprintf md chunk_size failed");
return 0;
}
/* old sysfs structure */
if (stat(path, &info) &&
dm_snprintf(path, PATH_MAX, "%s/block/md%d/md/chunk_size",
sysfs_dir, MINOR(dev->dev)) < 0) {
log_error("dm_snprintf old md chunk size failed");
return 0;
}
if (!(fp = fopen(path, "r"))) {
log_sys_error("fopen", path);
return 0;
}
if (!fgets(buffer, sizeof(buffer), fp)) {
log_sys_error("fgets", path);
goto out;
}
if (sscanf(buffer, "%lu", &chunk_size_bytes) != 1) {
log_error("sysfs file %s not in expected format: %s", path,
buffer);
goto out;
}
log_very_verbose("Device %s md chunk size is %lu bytes.",
dev_name(dev), chunk_size_bytes);
out:
if (fclose(fp))
log_sys_error("fclose", path);
return chunk_size_bytes >> SECTOR_SHIFT;
}
#else
int dev_is_md(struct device *dev __attribute((unused)),
uint64_t *sb __attribute((unused)))
{
return 0;
}
unsigned long dev_md_chunk_size(const char *sysfs_dir __attribute((unused)),
struct device *dev __attribute((unused)))
{
return 0UL;
}
#endif