We disable stripe size in __ext4_fill_super if it is not a multiple of
the cluster ratio however this check is missed when trying to remount.
This can leave us with cases where stripe < cluster_ratio after
remount:set making EXT4_B2C(sbi->s_stripe) become 0 that can cause some
unforeseen bugs like divide by 0.
Fix that by adding the check in remount path as well.
Reported-by: syzbot+1ad8bac5af24d01e2cbd@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+1ad8bac5af24d01e2cbd@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Fixes: c3defd99d58c ("ext4: treat stripe in block unit")
Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
---
fs/ext4/super.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e72145c4ae5a..9d495d78d262 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5165,6 +5165,18 @@ static int ext4_block_group_meta_init(struct super_block *sb, int silent)
return 0;
}
+/*
+ * It's hard to get stripe aligned blocks if stripe is not aligned with
+ * cluster, just disable stripe and alert user to simpfy code and avoid
+ * stripe aligned allocation which will rarely successes.
+ */
+static bool ext4_is_stripe_incompatible(struct super_block *sb, unsigned long stripe)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ return (stripe > 0 && sbi->s_cluster_ratio > 1 &&
+ stripe % sbi->s_cluster_ratio != 0);
+}
+
static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
{
struct ext4_super_block *es = NULL;
@@ -5272,13 +5284,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
goto failed_mount3;
sbi->s_stripe = ext4_get_stripe_size(sbi);
- /*
- * It's hard to get stripe aligned blocks if stripe is not aligned with
- * cluster, just disable stripe and alert user to simpfy code and avoid
- * stripe aligned allocation which will rarely successes.
- */
- if (sbi->s_stripe > 0 && sbi->s_cluster_ratio > 1 &&
- sbi->s_stripe % sbi->s_cluster_ratio != 0) {
+ if (ext4_is_stripe_incompatible(sb, sbi->s_stripe)) {
ext4_msg(sb, KERN_WARNING,
"stripe (%lu) is not aligned with cluster size (%u), "
"stripe is disabled",
@@ -6441,6 +6447,15 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
}
+ if ((ctx->spec & EXT4_SPEC_s_stripe) &&
+ ext4_is_stripe_incompatible(sb, ctx->s_stripe)) {
+ ext4_msg(sb, KERN_WARNING,
+ "stripe (%lu) is not aligned with cluster size (%u), "
+ "stripe is disabled",
+ ctx->s_stripe, sbi->s_cluster_ratio);
+ ctx->s_stripe = 0;
+ }
+
/*
* Changing the DIOREAD_NOLOCK or DELALLOC mount options may cause
* two calls to ext4_should_dioread_nolock() to return inconsistent
--
2.43.5
