Initial MDRAID support

.github/workflows/tests.yml

@@ -9,13 +9,13 @@ jobs:
       matrix:
         include:
         - os: ubuntu-22.04
-          pkgs: device-tree-compiler rauc simg2img u-boot-tools f2fs-tools arm-trusted-firmware-tools
+          pkgs: device-tree-compiler rauc simg2img u-boot-tools f2fs-tools arm-trusted-firmware-tools mdadm
         - os: ubuntu-22.04
-          pkgs: device-tree-compiler rauc simg2img u-boot-tools f2fs-tools arm-trusted-firmware-tools
+          pkgs: device-tree-compiler rauc simg2img u-boot-tools f2fs-tools arm-trusted-firmware-tools mdadm
           fake: sudo rm /usr/include/linux/fiemap.h /usr/include/linux/fs.h
           env: ac_cv_func_fallocate=no
         - os: ubuntu-20.04
-          pkgs: device-tree-compiler rauc simg2img u-boot-tools f2fs-tools
+          pkgs: device-tree-compiler rauc simg2img u-boot-tools f2fs-tools mdadm
 
     steps:
     - name: Inspect environment

Makefile.am

@@ -23,6 +23,7 @@ genimage_SOURCES = \
 	image-cramfs.c \
 	image-ext2.c \
 	image-f2fs.c \
+	image-mdraid.c \
 	image-btrfs.c \
 	image-file.c \
 	image-fip.c \
@@ -75,6 +76,7 @@ EXTRA_DIST += \
 	test/ext4test.1.dump \
 	test/ext4test.2.dump \
 	test/f2fs.config \
+	test/mdraid.config \
 	test/btrfs.config \
 	test/fip.config \
 	test/fit.its \

genimage.c

@@ -45,6 +45,7 @@ static struct image_handler *handlers[] = {
 	&ext3_handler,
 	&ext4_handler,
 	&f2fs_handler,
+	&mdraid_handler,
 	&btrfs_handler,
 	&file_handler,
 	&fit_handler,

genimage.h

@@ -112,6 +112,7 @@ extern struct image_handler ext2_handler;
 extern struct image_handler ext3_handler;
 extern struct image_handler ext4_handler;
 extern struct image_handler f2fs_handler;
+extern struct image_handler mdraid_handler;
 extern struct image_handler btrfs_handler;
 extern struct image_handler file_handler;
 extern struct image_handler flash_handler;

image-mdraid.c

@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2025 Tomas Mudrunka <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+
+MDRAID Superblock generator
+This should create valid mdraid superblock for raid1 with 1 device (more devices can be added once mounted).
+It is still very basic, but following seems to be working:
+
+mdadm --examine test.img
+losetup /dev/loop1 test.img
+mdadm --assemble md /dev/loop1
+
+Some docs:
+https://raid.wiki.kernel.org/index.php/RAID_superblock_formats#Sub-versions_of_the_version-1_superblock
+https://docs.huihoo.com/doxygen/linux/kernel/3.7/md__p_8h_source.html
+
+*/
+
+#include <confuse.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <linux/raid/md_p.h>
+
+#include "genimage.h"
+
+#define DATA_OFFSET_SECTORS	(2048)
+#define DATA_OFFSET_BYTES	(DATA_OFFSET_SECTORS*512)
+
+static void random_uuid(__u8 *buf)
+{
+	__u32 r[4];
+	for (int i = 0; i < 4; i++)
+		r[i] = random();
+	memcpy(buf, r, 16);
+}
+
+static unsigned int calc_sb_1_csum(struct mdp_superblock_1 * sb)
+{
+	unsigned int disk_csum, csum;
+	unsigned long long newcsum;
+	int size = sizeof(*sb) + __le32_to_cpu(sb->max_dev)*2;
+	unsigned int *isuper = (unsigned int*)sb;
+
+	/* make sure I can count... (needs include cstddef) */
+	/*
+	if (offsetof(struct mdp_superblock_1,data_offset) != 128 ||
+	    offsetof(struct mdp_superblock_1, utime) != 192 ||
+	    sizeof(struct mdp_superblock_1) != 256) {
+		fprintf(stderr, "WARNING - superblock isn't sized correctly\n");
+	}
+	*/
+
+	disk_csum = sb->sb_csum;
+	sb->sb_csum = 0;
+	newcsum = 0;
+	for (; size>=4; size -= 4 ) {
+		newcsum += __le32_to_cpu(*isuper);
+		isuper++;
+	}
+
+	if (size == 2)
+		newcsum += __le16_to_cpu(*(unsigned short*) isuper);
+
+	csum = (newcsum & 0xffffffff) + (newcsum >> 32);
+	sb->sb_csum = disk_csum;
+	return __cpu_to_le32(csum);
+}
+
+static int mdraid_generate(struct image *image) {
+	struct image *img_in = image->handler_priv;
+
+	int max_devices = 1;
+
+	char *name = cfg_getstr(image->imagesec, "label");
+
+	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->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*/
+
+	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
+					 * 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->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...*/
+		//#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,
+			* 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 */
+	//__u8	pad3[64-32];	/* 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.
+	 */
+	//__le16	dev_roles[];	/* role in array, or 0xffff for a spare, or 0xfffe for faulty */
+
+
+	//Calculate checksum
+	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) {
+		ret = insert_image(image, img_in, image->size-DATA_OFFSET_BYTES, DATA_OFFSET_BYTES, 0);
+		if(ret) return ret;
+	}
+
+	free(sb);
+
+	return 0;
+}
+
+static int mdraid_setup(struct image *image, cfg_t *cfg) {
+	srand(time(NULL)); //TODO: Should we seed UUID in more unique way?
+
+	int raid_level = cfg_getint(image->imagesec, "level");
+
+	if(raid_level != 1) {
+		image_error(image, "MDRAID Currently only supporting raid level 1 (mirror)!\n");
+		return 1;
+	}
+
+
+	struct image *img_in = NULL;
+	struct partition *part;
+	list_for_each_entry(part, &image->partitions, list) {
+		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) {
+				image_error(image, "MDRAID cannot contain more than one data partition!\n");
+				return 2;
+			}
+			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(!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);
+	}
+
+	return 0;
+}
+
+static cfg_opt_t mdraid_opts[] = {
+	CFG_STR("label", "localhost:42", CFGF_NONE),
+	CFG_INT("level", 1, CFGF_NONE),
+	CFG_END()
+};
+
+struct image_handler mdraid_handler = {
+	.type = "mdraid",
+	.generate = mdraid_generate,
+	.setup = mdraid_setup,
+	.opts = mdraid_opts,
+};

test/mdraid.config

@@ -0,0 +1,6 @@
+image test.mdraid {
+	mdraid {
+		level = 1
+	}
+	size = 5M
+}

test/misc.test

@@ -104,6 +104,14 @@ test_expect_success fiptool "fip" "
 	fiptool info images/test.fip
 "
 
+exec_test_set_prereq mdadm
+test_expect_success mdadm "mdraid" "
+	run_genimage_root mdraid.config test.mdraid &&
+	mdadm --examine images/test.mdraid &&
+	mdadm --examine images/test.mdraid | grep 'Checksum.*correct$' &&
+	mdadm --examine images/test.mdraid | grep 'State.*active$'
+"
+
 test_done
 
 # vim: syntax=sh