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* Copyright (C) 2008 Karel Zak <kzak@redhat.com>
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* Inspired by libvolume_id by
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* Kay Sievers <kay.sievers@vrfy.org>
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* This file may be redistributed under the terms of the
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* GNU Lesser General Public License.
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#include "superblocks.h"
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struct mdp0_super_block {
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uint32_t major_version;
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uint32_t minor_version;
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uint32_t patch_version;
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uint32_t gvalid_words;
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uint32_t not_persistent;
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* Version-1, little-endian.
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struct mdp1_super_block {
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/* constant array information - 128 bytes */
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uint32_t magic; /* MD_SB_MAGIC: 0xa92b4efc - little endian */
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uint32_t major_version; /* 1 */
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uint32_t feature_map; /* 0 for now */
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uint32_t pad0; /* always set to 0 when writing */
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uint8_t set_uuid[16]; /* user-space generated. */
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unsigned char set_name[32]; /* set and interpreted by user-space */
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uint64_t ctime; /* lo 40 bits are seconds, top 24 are microseconds or 0*/
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uint32_t level; /* -4 (multipath), -1 (linear), 0,1,4,5 */
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uint32_t layout; /* only for raid5 currently */
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uint64_t size; /* used size of component devices, in 512byte sectors */
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uint32_t chunksize; /* in 512byte sectors */
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uint32_t bitmap_offset; /* sectors after start of superblock that bitmap starts
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* NOTE: signed, so bitmap can be before superblock
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* only meaningful of feature_map[0] is set.
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/* These are only valid with feature bit '4' */
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uint32_t new_level; /* new level we are reshaping to */
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uint64_t reshape_position; /* next address in array-space for reshape */
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uint32_t delta_disks; /* change in number of raid_disks */
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uint32_t new_layout; /* new layout */
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uint32_t new_chunk; /* new chunk size (bytes) */
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uint8_t pad1[128-124]; /* set to 0 when written */
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/* constant this-device information - 64 bytes */
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uint64_t data_offset; /* sector start of data, often 0 */
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uint64_t data_size; /* sectors in this device that can be used for data */
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uint64_t super_offset; /* sector start of this superblock */
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uint64_t recovery_offset;/* sectors before this offset (from data_offset) have been recovered */
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uint32_t dev_number; /* permanent identifier of this device - not role in raid */
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uint32_t cnt_corrected_read; /* number of read errors that were corrected by re-writing */
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uint8_t device_uuid[16]; /* user-space setable, ignored by kernel */
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uint8_t devflags; /* per-device flags. Only one defined...*/
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uint8_t pad2[64-57]; /* set to 0 when writing */
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/* array state information - 64 bytes */
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uint64_t utime; /* 40 bits second, 24 btes microseconds */
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uint64_t events; /* incremented when superblock updated */
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uint64_t resync_offset; /* data before this offset (from data_offset) known to be in sync */
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uint32_t sb_csum; /* checksum upto dev_roles[max_dev] */
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uint32_t max_dev; /* size of dev_roles[] array to consider */
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uint8_t pad3[64-32]; /* set to 0 when writing */
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/* device state information. Indexed by dev_number.
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* Note there are no per-device state flags. State information is rolled
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* into the 'roles' value. If a device is spare or faulty, then it doesn't
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* have a meaningful role.
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uint16_t dev_roles[0]; /* role in array, or 0xffff for a spare, or 0xfffe for faulty */
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#define MD_RESERVED_BYTES 0x10000
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#define MD_SB_MAGIC 0xa92b4efc
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static int probe_raid0(blkid_probe pr, blkid_loff_t off)
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struct mdp0_super_block *mdp0;
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if (pr->size < MD_RESERVED_BYTES)
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mdp0 = (struct mdp0_super_block *)
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blkid_probe_get_buffer(pr,
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sizeof(struct mdp0_super_block));
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memset(uuid.ints, 0, sizeof(uuid.ints));
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if (le32_to_cpu(mdp0->md_magic) == MD_SB_MAGIC) {
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uuid.ints[0] = swab32(mdp0->set_uuid0);
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if (le32_to_cpu(mdp0->minor_version) >= 90) {
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uuid.ints[1] = swab32(mdp0->set_uuid1);
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uuid.ints[2] = swab32(mdp0->set_uuid2);
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uuid.ints[3] = swab32(mdp0->set_uuid3);
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ma = le32_to_cpu(mdp0->major_version);
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mi = le32_to_cpu(mdp0->minor_version);
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pa = le32_to_cpu(mdp0->patch_version);
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size = le32_to_cpu(mdp0->size);
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} else if (be32_to_cpu(mdp0->md_magic) == MD_SB_MAGIC) {
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uuid.ints[0] = mdp0->set_uuid0;
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if (be32_to_cpu(mdp0->minor_version) >= 90) {
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uuid.ints[1] = mdp0->set_uuid1;
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uuid.ints[2] = mdp0->set_uuid2;
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uuid.ints[3] = mdp0->set_uuid3;
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ma = be32_to_cpu(mdp0->major_version);
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mi = be32_to_cpu(mdp0->minor_version);
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pa = be32_to_cpu(mdp0->patch_version);
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size = be32_to_cpu(mdp0->size);
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size <<= 10; /* convert KiB to bytes */
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if (pr->size < 0 || (uint64_t) pr->size < size + MD_RESERVED_BYTES)
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/* device is too small */
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if (off < 0 || (uint64_t) off < size)
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/* no space before superblock */
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* Check for collisions between RAID and partition table
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* For example the superblock is at the end of the last partition, it's
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* the same possition as at the end of the disk...
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if ((S_ISREG(pr->mode) || blkid_probe_is_wholedisk(pr)) &&
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blkid_probe_is_covered_by_pt(pr,
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off - size, /* min. start */
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size + MD_RESERVED_BYTES)) { /* min. length */
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/* ignore this superblock, it's within any partition and
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* we are working with whole-disk now */
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if (blkid_probe_sprintf_version(pr, "%u.%u.%u", ma, mi, pa) != 0)
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if (blkid_probe_set_uuid(pr, (unsigned char *) uuid.bytes) != 0)
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if (blkid_probe_set_magic(pr, off, sizeof(mdp0->md_magic),
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(unsigned char *) &mdp0->md_magic))
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static int probe_raid1(blkid_probe pr, off_t off)
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struct mdp1_super_block *mdp1;
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mdp1 = (struct mdp1_super_block *)
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blkid_probe_get_buffer(pr,
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sizeof(struct mdp1_super_block));
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if (le32_to_cpu(mdp1->magic) != MD_SB_MAGIC)
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if (le32_to_cpu(mdp1->major_version) != 1U)
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if (le64_to_cpu(mdp1->super_offset) != (uint64_t) off >> 9)
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if (blkid_probe_set_uuid(pr, (unsigned char *) mdp1->set_uuid) != 0)
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if (blkid_probe_set_uuid_as(pr,
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(unsigned char *) mdp1->device_uuid, "UUID_SUB") != 0)
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if (blkid_probe_set_label(pr, mdp1->set_name,
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sizeof(mdp1->set_name)) != 0)
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if (blkid_probe_set_magic(pr, off, sizeof(mdp1->magic),
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(unsigned char *) &mdp1->magic))
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int probe_raid(blkid_probe pr,
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const struct blkid_idmag *mag __attribute__((__unused__)))
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const char *ver = NULL;
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if (pr->size > MD_RESERVED_BYTES) {
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/* version 0 at the end of the device */
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uint64_t sboff = (pr->size & ~(MD_RESERVED_BYTES - 1))
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if (probe_raid0(pr, sboff) == 0)
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/* version 1.0 at the end of the device */
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sboff = (pr->size & ~(0x1000 - 1)) - 0x2000;
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if (probe_raid1(pr, sboff) == 0)
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/* version 1.1 at the start of the device */
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if (probe_raid1(pr, 0) == 0)
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/* version 1.2 at 4k offset from the start */
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else if (probe_raid1(pr, 0x1000) == 0)
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blkid_probe_set_version(pr, ver);
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const struct blkid_idinfo linuxraid_idinfo = {
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.name = "linux_raid_member",
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.usage = BLKID_USAGE_RAID,
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.probefunc = probe_raid,
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.magics = BLKID_NONE_MAGIC
added
removed
libblkid/src/superblocks/linux_raid.c
