From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [patch 4/6] vfs: mountinfo show dominating group id
Date: Wed, 19 Mar 2008 11:37:04 +0000
Message-ID: <20080319113704.GJ10722@ZenIV.linux.org.uk>
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To: Miklos Szeredi <miklos@szeredi.hu>
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On Thu, Mar 13, 2008 at 10:26:45PM +0100, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@suse.cz>
> 
> Show peer group ID of nearest dominating group that has intersection
> with the mount's namespace.

There's an obvious problem here: ->show_options() can spew _anything_,
including a string that ends on " shared:42".  Makes reliable parsing of
the damn thing in userland impossible.  IOW, fs options should go _last_
and they should follow an unconditionally present field.

>  	if (sb->s_op->show_options)
>  		err = sb->s_op->show_options(m, mnt);
> -	if (IS_MNT_SHARED(mnt)) {
> -		seq_printf(m, " shared:%i", get_peer_group_id(mnt));
> -		if (IS_MNT_SLAVE(mnt))
> -			seq_printf(m, ",slave:%i", get_master_id(mnt));
> -	} else if (IS_MNT_SLAVE(mnt)) {
> -		seq_printf(m, " slave:%i", get_master_id(mnt));
> +	seq_putc(m, ' ');
> +	if (IS_MNT_SHARED(mnt) || IS_MNT_SLAVE(mnt)) {
> +		if (IS_MNT_SHARED(mnt))
> +			seq_printf(m, "shared:%i", get_peer_group_id(mnt));
> +		if (IS_MNT_SLAVE(mnt)) {
> +			int dominator_id = get_dominator_id_same_ns(mnt);