### Comments for ChangeSet
Superblock format '1' resolves a number of issues with
superblock format '0'.
It is more dense and can support many more sub-devices.
It does not contains un-needed redundancy.
It adds a few new useful fields
----------- Diffstat output ------------
./drivers/md/md.c | 213 +++++++++++++++++++++++++++++++++++++++++++-
./include/linux/raid/md_p.h | 53 ++++++++++
2 files changed, 264 insertions(+), 2 deletions(-)
diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~ 2003-03-12 13:46:37.000000000 +1100
+++ ./drivers/md/md.c 2003-03-12 13:46:39.000000000 +1100
@@ -763,6 +763,210 @@ static void super_90_sync(mddev_t *mddev
sb->sb_csum = calc_sb_csum(sb);
}
+/*
+ * version 1 superblock
+ */
+
+static unsigned int calc_sb_1_csum(struct mdp_superblock_1 * sb)
+{
+ unsigned int disk_csum, csum;
+ int size = 256 + sb->max_dev*2;
+
+ disk_csum = sb->sb_csum;
+ sb->sb_csum = 0;
+ csum = csum_partial((void *)sb, size, 0);
+ sb->sb_csum = disk_csum;
+ return csum;
+}
+
+static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
+{
+ struct mdp_superblock_1 *sb;
+ int ret;
+ sector_t sb_offset;
+
+ /*
+ * Calculate the position of the superblock.
+ * It is always aligned to a 4K boundary and
+ * depeding 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.
+ */
+ switch(minor_version) {
+ case 0:
+ sb_offset = rdev->bdev->bd_inode->i_size >> 9;
+ sb_offset -= 8*2;
+ sb_offset &= ~(4*2);
+ /* convert from sectors to K */
+ sb_offset /= 2;
+ break;
+ case 1:
+ sb_offset = 0;
+ break;
+ case 2:
+ sb_offset = 4;
+ break;
+ default:
+ return -EINVAL;
+ }
+ rdev->sb_offset = sb_offset;
+
+ ret = read_disk_sb(rdev);
+ if (ret) return ret;
+
+
+ sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
+
+ if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
+ sb->major_version != cpu_to_le32(1) ||
+ le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
+ le64_to_cpu(sb->super_offset) != (rdev->sb_offset<<1) ||
+ sb->feature_map != 0)
+ return -EINVAL;
+
+ if (calc_sb_1_csum(sb) != sb->sb_csum) {
+ printk(BAD_CSUM, bdev_partition_name(rdev->bdev));
+ return -EINVAL;
+ }
+ rdev->preferred_minor = 0xffff;
+ rdev->data_offset = le64_to_cpu(sb->data_offset);
+
+ if (refdev == 0)
+ return 1;
+ else {
+ __u64 ev1, ev2;
+ struct mdp_superblock_1 *refsb =
+ (struct mdp_superblock_1*)page_address(refdev->sb_page);
+
+ if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
+ sb->level != refsb->level ||
+ sb->layout != refsb->layout ||
+ sb->chunksize != refsb->chunksize) {
+ printk(KERN_WARNING "md: %s has strangely different superblock to %s\n",
+ bdev_partition_name(rdev->bdev),
+ bdev_partition_name(refdev->bdev));
+ return -EINVAL;
+ }
+ ev1 = le64_to_cpu(sb->events);
+ ev2 = le64_to_cpu(refsb->events);
+
+ if (ev1 > ev2)
+ return 1;
+ }
+ if (minor_version)
+ rdev->size = ((rdev->bdev->bd_inode->i_size>>9) - le64_to_cpu(sb->data_offset)) / 2;
+ else
+ rdev->size = rdev->sb_offset;
+ if (rdev->size < le64_to_cpu(sb->data_size)/2)
+ return -EINVAL;
+ rdev->size = le64_to_cpu(sb->data_size)/2;
+ if (le32_to_cpu(sb->chunksize))
+ rdev->size &= ~((sector_t)le32_to_cpu(sb->chunksize)/2 - 1);
+ return 0;
+}
+
+static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+ struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
+
+ if (mddev->raid_disks == 0) {
+ mddev->major_version = 1;
+ mddev->minor_version = 0;
+ mddev->patch_version = 0;
+ mddev->persistent = 1;
+ mddev->chunk_size = le32_to_cpu(sb->chunksize) << 9;
+ mddev->ctime = le64_to_cpu(sb->ctime) & ((1ULL << 32)-1);
+ mddev->utime = le64_to_cpu(sb->utime) & ((1ULL << 32)-1);
+ mddev->level = le32_to_cpu(sb->level);
+ mddev->layout = le32_to_cpu(sb->layout);
+ mddev->raid_disks = le32_to_cpu(sb->raid_disks);
+ mddev->size = (u32)le64_to_cpu(sb->size);
+ mddev->events = le64_to_cpu(sb->events);
+
+ mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
+ memcpy(mddev->uuid, sb->set_uuid, 16);
+
+ mddev->max_disks = (4096-256)/2;
+ } else {
+ __u64 ev1;
+ ev1 = le64_to_cpu(sb->events);
+ ++ev1;
+ if (ev1 < mddev->events)
+ return -EINVAL;
+ }
+
+ if (mddev->level != LEVEL_MULTIPATH) {
+ int role;
+ rdev->desc_nr = le32_to_cpu(sb->dev_number);
+ role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
+ switch(role) {
+ case 0xffff: /* spare */
+ rdev->in_sync = 0;
+ rdev->faulty = 0;
+ rdev->raid_disk = -1;
+ break;
+ case 0xfffe: /* faulty */
+ rdev->in_sync = 0;
+ rdev->faulty = 1;
+ rdev->raid_disk = -1;
+ break;
+ default:
+ rdev->in_sync = 1;
+ rdev->faulty = 0;
+ rdev->raid_disk = role;
+ break;
+ }
+ }
+ return 0;
+}
+
+static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+ struct mdp_superblock_1 *sb;
+ struct list_head *tmp;
+ mdk_rdev_t *rdev2;
+ int max_dev, i;
+ /* make rdev->sb match mddev and rdev data. */
+
+ sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
+
+ sb->feature_map = 0;
+ sb->pad0 = 0;
+ memset(sb->pad1, 0, sizeof(sb->pad1));
+ memset(sb->pad2, 0, sizeof(sb->pad2));
+ memset(sb->pad3, 0, sizeof(sb->pad3));
+
+ sb->utime = cpu_to_le64((__u64)mddev->utime);
+ sb->events = cpu_to_le64(mddev->events);
+ if (mddev->in_sync)
+ sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
+ else
+ sb->resync_offset = cpu_to_le64(0);
+
+ max_dev = 0;
+ ITERATE_RDEV(mddev,rdev2,tmp)
+ if (rdev2->desc_nr > max_dev)
+ max_dev = rdev2->desc_nr;
+
+ sb->max_dev = max_dev;
+ for (i=0; i<max_dev;i++)
+ sb->dev_roles[max_dev] = cpu_to_le16(0xfffe);
+
+ ITERATE_RDEV(mddev,rdev2,tmp) {
+ i = rdev2->desc_nr;
+ if (rdev2->faulty)
+ sb->dev_roles[i] = cpu_to_le16(0xfffe);
+ else if (rdev2->in_sync)
+ sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
+ else
+ sb->dev_roles[i] = cpu_to_le16(0xffff);
+ }
+
+ sb->recovery_offset = cpu_to_le64(0); /* not supported yet */
+}
+
+
struct super_type super_types[] = {
[0] = {
.name = "0.90.0",
@@ -771,9 +975,14 @@ struct super_type super_types[] = {
.validate_super = super_90_validate,
.sync_super = super_90_sync,
},
+ [1] = {
+ .name = "md-1",
+ .owner = THIS_MODULE,
+ .load_super = super_1_load,
+ .validate_super = super_1_validate,
+ .sync_super = super_1_sync,
+ },
};
-
-
static mdk_rdev_t * match_dev_unit(mddev_t *mddev, mdk_rdev_t *dev)
{
diff ./include/linux/raid/md_p.h~current~ ./include/linux/raid/md_p.h
--- ./include/linux/raid/md_p.h~current~ 2003-03-12 13:46:37.000000000 +1100
+++ ./include/linux/raid/md_p.h 2003-03-12 13:46:39.000000000 +1100
@@ -173,5 +173,58 @@ static inline __u64 md_event(mdp_super_t
return (ev<<32)| sb->events_lo;
}
+/*
+ * The version-1 superblock :
+ * All numeric fields are little-endian.
+ *
+ * total size: 256 bytes plus 2 per device.
+ * 1K allows 384 devices.
+ */
+struct mdp_superblock_1 {
+ /* constant array information - 128 bytes */
+ __u32 magic; /* MD_SB_MAGIC: 0xa92b4efc - little endian */
+ __u32 major_version; /* 1 */
+ __u32 feature_map; /* 0 for now */
+ __u32 pad0; /* always set to 0 when writing */
+
+ __u8 set_uuid[16]; /* user-space generated. */
+ char set_name[32]; /* set and interpreted by user-space */
+
+ __u64 ctime; /* lo 40 bits are seconds, top 24 are microseconds or 0*/
+ __u32 level; /* -4 (multipath), -1 (linear), 0,1,4,5 */
+ __u32 layout; /* only for raid5 currently */
+ __u64 size; /* used size of component devices, in 512byte sectors */
+
+ __u32 chunksize; /* in 512byte sectors */
+ __u32 raid_disks;
+ __u8 pad1[128-92]; /* set to 0 when written */
+
+ /* constant this-device information - 64 bytes */
+ __u64 data_offset; /* sector start of data, often 0 */
+ __u64 data_size; /* sectors in this device that can be used for data */
+ __u64 super_offset; /* sector start of this superblock */
+ __u64 recovery_offset;/* sectors before this offset (from data_offset) have been recovered */
+ __u32 dev_number; /* permanent identifier of this device - not role in raid */
+ __u32 cnt_corrected_read; /* number of read errors that were corrected by re-writing */
+ __u8 device_uuid[16]; /* user-space setable, ignored by kernel */
+ __u8 pad2[64-56]; /* set to 0 when writing */
+
+ /* array state information - 64 bytes */
+ __u64 utime; /* 40 bits second, 24 btes microseconds */
+ __u64 events; /* incremented when superblock updated */
+ __u64 resync_offset; /* data before this offset (from data_offset) known to be in sync */
+ __u32 sb_csum; /* checksum upto devs[max_dev] */
+ __u32 max_dev; /* size of devs[] array to consider */
+ __u8 pad3[64-40]; /* set to 0 when writing */
+
+ /* device state information. Indexed by dev_number.
+ * 2 bytes per device
+ * Note there are no per-device state flags. State information is rolled
+ * into the 'roles' value. If a device is spare or faulty, then it doesn't
+ * have a meaningful role.
+ */
+ __u16 dev_roles[0]; /* role in array, or 0xffff for a spare, or 0xfffe for faulty */
+};
+
#endif
-
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