From 9c47127a807da3e36ce80f7c83a1134a291fc021 Mon Sep 17 00:00:00 2001 From: Li Nan Date: Mon, 3 Nov 2025 20:57:56 +0800 Subject: [PATCH] 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: Li Nan Reviewed-by: Xiao Ni Signed-off-by: Yu Kuai --- drivers/md/md.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 6193f5b2017d..9676e2477df6 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -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 */ - return -EINVAL; + 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");