linux-kernel - Re: [PATCH] ext4: Fix incorrect group count in ext4_fill

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Message-ID: <20200329024709.GK53396@mit.edu>
Date:   Sat, 28 Mar 2020 22:47:09 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Josh Triplett <josh@...htriplett.org>
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andreas Dilger <adilger.kernel@...ger.ca>
Subject: Re: [PATCH] ext4: Fix incorrect group count in ext4_fill_super error
 message

On Sat, Mar 28, 2020 at 02:54:01PM -0700, Josh Triplett wrote:
> ext4_fill_super doublechecks the number of groups before mounting; if
> that check fails, the resulting error message prints the group count
> from the ext4_sb_info sbi, which hasn't been set yet. Print the freshly
> computed group count instead (which at that point has just been computed
> in "blocks_count").
> 
> Signed-off-by: Josh Triplett <josh@...htriplett.org>
> Fixes: 4ec1102813798 ("ext4: Add sanity checks for the superblock before mounting the filesystem")

Applied, with a fix to the format string:

>  fs/ext4/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 0c7c4adb664e..7f5f37653a03 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4288,7 +4288,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	if (blocks_count > ((uint64_t)1<<32) - EXT4_DESC_PER_BLOCK(sb)) {
>  		ext4_msg(sb, KERN_WARNING, "groups count too large: %u "

s/%u/%llu/

>  		       "(block count %llu, first data block %u, "
> -		       "blocks per group %lu)", sbi->s_groups_count,
> +		       "blocks per group %lu)", blocks_count,
>  		       ext4_blocks_count(es),
>  		       le32_to_cpu(es->s_first_data_block),
>  		       EXT4_BLOCKS_PER_GROUP(sb));
> -- 
> 2.26.0

						- Ted