linux-ext4 - Re: [PATCH] ext4: Verify s_clusters_per

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Date: Mon, 19 Feb 2024 17:59:18 +0100
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...wei.com>
Cc: Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org,
	Ted Tso <tytso@....edu>
Subject: Re: [PATCH] ext4: Verify s_clusters_per_group even without bigalloc

On Sun 18-02-24 10:16:40, Zhang Yi wrote:
> Hello!
> 
> On 2024/2/13 18:15, Jan Kara wrote:
> > Currently we ignore s_clusters_per_group field in the on-disk superblock
> > if bigalloc feature is not enabled. However e2fsprogs don't even open
> > the filesystem is s_clusters_per_group is invalid. This results in an
>                  ^^
>                  if
> > odd state where kernel happily works with the filesystem while even
> > e2fsck refuses to touch it. Verify that s_clusters_per_group is valid
> > even if bigalloc feature is not enabled to make things consistent. Due
> > to current e2fsprogs behavior it is unlikely there are filesystems out
> > in the wild (except for intentionally fuzzed ones) with invalid
> > s_clusters_per_group counts.
> > 
> > Signed-off-by: Jan Kara <jack@...e.cz>
> > ---
> >  fs/ext4/super.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > index 0f931d0c227d..522683075067 100644
> > --- a/fs/ext4/super.c
> > +++ b/fs/ext4/super.c
> > @@ -4451,7 +4451,15 @@ static int ext4_handle_clustersize(struct super_block *sb)
> >  				 sbi->s_blocks_per_group);
> >  			return -EINVAL;
> >  		}
> > -		sbi->s_clusters_per_group = sbi->s_blocks_per_group;
> > +		sbi->s_clusters_per_group =
> > +			le32_to_cpu(es->s_clusters_per_group);
> > +		if (sbi->s_blocks_per_group != sbi->s_clusters_per_group) {
> > +			ext4_msg(sb, KERN_ERR, "blocks per group (%lu) and "
> > +				 "clusters per group (%lu) inconsistent",
> > +				 sbi->s_blocks_per_group,
> > +				 sbi->s_clusters_per_group);
> > +			return -EINVAL;
> > +		}
> 
> This is almost the same with the code snippet in bigalloc branch, would
> it be better to factor them out and reuse this hunk in both branch, just
> like the check e2fsprogs does?

Yeah, good point. Let me send v2.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR