linux-kernel - Re: [PATCH] ext4: bad mount opts in no journal mode

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Date:   Sun, 28 Apr 2019 22:21:54 +0200
From:   Jan Kara <jack@...e.cz>
To:     Debabrata Banerjee <dbanerje@...mai.com>
Cc:     Theodore Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-ext4@...r.kernel.org, Dmitry Monakhov <dmonakhov@...nvz.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ext4: bad mount opts in no journal mode

On Thu 11-04-19 17:49:17, Debabrata Banerjee wrote:
> Fixes:
> commit 1e381f60dad9 ("ext4: do not allow journal_opts for fs w/o journal")
> 
> Instead of removing EXT4_MOUNT_JOURNAL_CHECKSUM from s_def_mount_opt as
> I assume was intended, all other options were blown away leading to
> _ext4_show_options() output being incorrect. I don't see why this or
> other journal related flags should be removed from s_def_mount_opt
> regardless, it is only used for comparison to display opts, and we
> already made sure they couldn't be set.
> 
> Signed-off-by: Debabrata Banerjee <dbanerje@...mai.com>

So I agree that the clearing is wrong. But I don't agree with just deleting
the line. We could have JOURNAL_CHECKSUM in s_def_mount_opt in nojournal
mode and in such case we don't want to show in /proc/mounts
nojournal_checksum as a mount option. So the line should be really fixed
to:

	sbi->s_def_mount_opt &= ~EXT4_MOUNT_JOURNAL_CHECKSUM;

								Honza

> ---
>  fs/ext4/super.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 6ed4eb81e674..63eef29666e0 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4238,7 +4238,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  				 "data=, fs mounted w/o journal");
>  			goto failed_mount_wq;
>  		}
> -		sbi->s_def_mount_opt &= EXT4_MOUNT_JOURNAL_CHECKSUM;
>  		clear_opt(sb, JOURNAL_CHECKSUM);
>  		clear_opt(sb, DATA_FLAGS);
>  		sbi->s_journal = NULL;
> -- 
> 2.21.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR