Skip to content

Commit

Permalink
MDRAID: Reflected first part of suggestions made by @michaelolbrich
Browse files Browse the repository at this point in the history 
Signed-off-by: Tomas Mudrunka <[email protected]>
  • Loading branch information
@Harvie
Harvie committed Dec 20, 2024
1 parent 3f7ec9f commit bfa2c22
Showing 1 changed file with 37 additions and 39 deletions.
76 changes: 37 additions & 39 deletions image-mdraid.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ Some docs:

#define DATA_OFFSET_SECTORS (2048)
#define DATA_OFFSET_BYTES (DATA_OFFSET_SECTORS*512)
#define MDRAID_MAGIC 0xa92b4efc

static void random_uuid(__u8 *buf)
{
Expand Down Expand Up @@ -90,54 +91,54 @@ static int mdraid_generate(struct image *image) {

char *name = cfg_getstr(image->imagesec, "label");

struct mdp_superblock_1 *sb = xzalloc(sizeof(struct mdp_superblock_1)+max_devices*2);
struct mdp_superblock_1 *sb = xzalloc(sizeof(struct mdp_superblock_1) + max_devices*2);

/* constant array information - 128 bytes */
sb->magic = 0xa92b4efc; /* MD_SB_MAGIC: 0xa92b4efc - little endian */
sb->magic = MDRAID_MAGIC; /* MD_SB_MAGIC: 0xa92b4efc - little endian */
sb->major_version = 1; /* 1 */
sb->feature_map = 0; //MD_FEATURE_BITMAP_OFFSET; /* bit 0 set if 'bitmap_offset' is meaningful */ //TODO: internal bitmap bit is ignored, unless there is correct bitmap with BITMAP_MAGIC in place
sb->pad0 = 0; /* always set to 0 when writing */

random_uuid(sb->set_uuid); /* user-space generated. U8[16]*/ //TODO: should we allow user to set this?
strncpy(sb->set_name, name, 32); sb->set_name[31]=0; /* set and interpreted by user-space. CHAR[32] */
sb->ctime=time(NULL); /* lo 40 bits are seconds, top 24 are microseconds or 0*/
strncpy(sb->set_name, name, 32); sb->set_name[31] = 0; /* set and interpreted by user-space. CHAR[32] */
sb->ctime = time(NULL) & 0xffffffffff; /* lo 40 bits are seconds, top 24 are microseconds or 0*/

sb->level=1; /* -4 (multipath), -1 (linear), 0,1,4,5 */
//sb->layout=2; /* only for raid5 and raid10 currently */
sb->size=(image->size - DATA_OFFSET_BYTES)/512; /* used size of component devices, in 512byte sectors */
sb->level = 1; /* -4 (multipath), -1 (linear), 0,1,4,5 */
//sb->layout = 2; /* only for raid5 and raid10 currently */
sb->size = (image->size - DATA_OFFSET_BYTES)/512; /* used size of component devices, in 512byte sectors */

sb->chunksize=0; /* in 512byte sectors - not used in raid 1 */
sb->raid_disks=1;
sb->bitmap_offset=8; /* sectors after start of superblock that bitmap starts
sb->chunksize = 0; /* in 512byte sectors - not used in raid 1 */
sb->raid_disks = 1;
sb->bitmap_offset = 8; /* sectors after start of superblock that bitmap starts
* NOTE: signed, so bitmap can be before superblock
* only meaningful of feature_map[0] is set.
*/

/* constant this-device information - 64 bytes */
sb->data_offset=DATA_OFFSET_SECTORS; /* sector start of data, often 0 */
sb->data_size=(image->size - DATA_OFFSET_BYTES)/512; /* sectors in this device that can be used for data */
sb->super_offset=8; /* sector start of this superblock */
sb->data_offset = DATA_OFFSET_SECTORS; /* sector start of data, often 0 */
sb->data_size = (image->size - DATA_OFFSET_BYTES)/512; /* sectors in this device that can be used for data */
sb->super_offset = 8; /* sector start of this superblock */

sb->dev_number=0; /* permanent identifier of this device - not role in raid */
sb->cnt_corrected_read=0; /* number of read errors that were corrected by re-writing */
sb->dev_number = 0; /* permanent identifier of this device - not role in raid */
sb->cnt_corrected_read = 0; /* number of read errors that were corrected by re-writing */
random_uuid(sb->device_uuid); /* user-space setable, ignored by kernel U8[16] */ //TODO: should we allow user to set this?
sb->devflags=0; /* per-device flags. Only two defined...*/
sb->devflags = 0; /* per-device flags. Only two defined...*/
//#define WriteMostly1 1 /* mask for writemostly flag in above */
//#define FailFast1 2 /* Should avoid retries and fixups and just fail */

/* Bad block log. If there are any bad blocks the feature flag is set.
* If offset and size are non-zero, that space is reserved and available
*/
sb->bblog_shift=9; /* shift from sectors to block size */ //TODO: not sure why this is 9
sb->bblog_size=8; /* number of sectors reserved for list */
sb->bblog_offset=16; /* sector offset from superblock to bblog,
sb->bblog_shift = 9; /* shift from sectors to block size */ //TODO: not sure why this is 9
sb->bblog_size = 8; /* number of sectors reserved for list */
sb->bblog_offset = 16; /* sector offset from superblock to bblog,
* signed - not unsigned */

/* array state information - 64 bytes */
sb->utime=0; /* 40 bits second, 24 bits microseconds */
sb->events=0; /* incremented when superblock updated */
sb->resync_offset=0; /* data before this offset (from data_offset) known to be in sync */
sb->max_dev=max_devices; /* size of devs[] array to consider */
sb->utime = 0; /* 40 bits second, 24 bits microseconds */
sb->events = 0; /* incremented when superblock updated */
sb->resync_offset = 0; /* data before this offset (from data_offset) known to be in sync */
sb->max_dev = max_devices; /* size of devs[] array to consider */
//__u8 pad3[64-32]; /* set to 0 when writing */

/* device state information. Indexed by dev_number.
Expand All @@ -150,18 +151,18 @@ static int mdraid_generate(struct image *image) {


//Calculate checksum
sb->sb_csum=calc_sb_1_csum(sb);
sb->sb_csum = calc_sb_1_csum(sb);


//construct image file
int ret;
ret = prepare_image(image, image->size);
if(ret) return ret;
ret = insert_data(image, sb, imageoutfile(image), sizeof(struct mdp_superblock_1)+max_devices*2, 8*512);
if(ret) return ret;
if(img_in) {
if (ret) return ret;
ret = insert_data(image, sb, imageoutfile(image), sizeof(struct mdp_superblock_1) + max_devices*2, 8*512);
if (ret) return ret;
if (img_in) {
ret = insert_image(image, img_in, image->size-DATA_OFFSET_BYTES, DATA_OFFSET_BYTES, 0);
if(ret) return ret;
if (ret) return ret;
}

free(sb);
Expand All @@ -174,7 +175,7 @@ static int mdraid_setup(struct image *image, cfg_t *cfg) {

int raid_level = cfg_getint(image->imagesec, "level");

if(raid_level != 1) {
if (raid_level != 1) {
image_error(image, "MDRAID Currently only supporting raid level 1 (mirror)!\n");
return 1;
}
Expand All @@ -183,31 +184,28 @@ static int mdraid_setup(struct image *image, cfg_t *cfg) {
struct image *img_in = NULL;
struct partition *part;
list_for_each_entry(part, &image->partitions, list) {
if(strcmp(part->name, "data")) {
if (strcmp(part->name, "data")) {
image_info(image, "MDRAID partition has to be called 'data' instead of '%s'\n", part->name);
} else {
if(img_in) {
if (img_in) {
image_error(image, "MDRAID cannot contain more than one data partition!\n");
return 2;
}
if(part->image) {
if (part->image) {
image_info(image, "MDRAID using data from [%s]: %s\n", part->name, part->image);
img_in = image_get(part->image);
if(image->size < (img_in->size + DATA_OFFSET_BYTES)) image->size = (img_in->size + DATA_OFFSET_BYTES);
if (image->size < (img_in->size + DATA_OFFSET_BYTES)) image->size = (img_in->size + DATA_OFFSET_BYTES);
}
}
}
if(!img_in) {
if (!img_in) {
image_info(image, "MDRAID is created without data.\n");
}
image->handler_priv = img_in;


//Make sure size is aligned (should be divisible by 8 sectors to keep 4kB alignment)
int align = 8*512;
if(image->size % align) {
image->size += align-(image->size % align);
}
image->size = roundup(image->size, 8*512);

return 0;
}
Expand Down

0 comments on commit bfa2c22

Please sign in to comment.