Commit 9c47127a authored by Li Nan's avatar Li Nan Committed by Yu Kuai
Browse files

md: add check_new_feature module parameter 

Raid checks if pad3 is zero when loading superblock from disk. Arrays
created with new features may fail to assemble on old kernels as pad3
is used.

Add module parameter check_new_feature to bypass this check.

Link: https://lore.kernel.org/linux-raid/20251103125757.1405796-5-linan666@huaweicloud.com


Signed-off-by: default avatarLi Nan <linan122@huawei.com>
Reviewed-by: default avatarXiao Ni <xni@redhat.com>
Signed-off-by: default avatarYu Kuai <yukuai@fnnas.com>
parent 2107457e

drivers/md/md.c

+9 −3
Original line number Diff line number Diff line
@@ -339,6 +339,7 @@ static int start_readonly; 
 */

static bool create_on_open = true;

static bool legacy_async_del_gendisk = true;

static bool check_new_feature = true;



/*

 * We have a system wide 'event count' that is incremented
@@ -1851,9 +1852,13 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_ 
	}

	if (sb->pad0 ||

	    sb->pad3[0] ||

	    memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1])))

		/* Some padding is non-zero, might be a new feature */

	    memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1]))) {

		pr_warn("Some padding is non-zero on %pg, might be a new feature\n",

			rdev->bdev);

		if (check_new_feature)

			return -EINVAL;

		pr_warn("check_new_feature is disabled, data corruption possible\n");

	}



	rdev->preferred_minor = 0xffff;

	rdev->data_offset = le64_to_cpu(sb->data_offset);
@@ -10741,6 +10746,7 @@ module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR); 
module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);

module_param(create_on_open, bool, S_IRUSR|S_IWUSR);

module_param(legacy_async_del_gendisk, bool, 0600);

module_param(check_new_feature, bool, 0600);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("MD RAID framework");