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ext4: check stripe size compatibility on remount as well

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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: c3defd99d5 ("ext4: treat stripe in block unit")
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/3a493bb503c3598e25dcfbed2936bb2dff3fece7.1725002410.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Ojaswin Mujoo 2024-08-30 12:50:57 +05:30 committed by Theodore Ts'o
parent cc749e61c0
commit ee85e0938a
1 changed files with 22 additions and 7 deletions
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29
fs/ext4/super.c
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@ -5178,6 +5178,18 @@ 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;
@ -5287,13 +5299,7 @@ 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",
@ -6457,6 +6463,15 @@ 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