6.10-stable review patch. If anyone has any objections, please let me know.
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From: Ojaswin Mujoo ojaswin@linux.ibm.com
[ Upstream commit ee85e0938aa8f9846d21e4d302c3cf6a2a75110d ]
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@syzkaller.appspotmail.com Tested-by: syzbot+1ad8bac5af24d01e2cbd@syzkaller.appspotmail.com Reviewed-by: Kemeng Shi shikemeng@huaweicloud.com Reviewed-by: Ritesh Harjani (IBM) ritesh.list@gmail.com Fixes: c3defd99d58c ("ext4: treat stripe in block unit") Signed-off-by: Ojaswin Mujoo ojaswin@linux.ibm.com Link: https://patch.msgid.link/3a493bb503c3598e25dcfbed2936bb2dff3fece7.1725002410... Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c682fb927b64b..edc692984404d 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5177,6 +5177,18 @@ 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 simplify code and avoid + * stripe aligned allocation which will rarely succeed. + */ +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; @@ -5284,13 +5296,7 @@ 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", @@ -6453,6 +6459,15 @@ 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