linux-kernel - Re: [PATCH 3/3] Btrfs: show subvol= and subvolid= in /proc/mounts

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150409155630.GF25622@twin.jikos.cz>
Date:	Thu, 9 Apr 2015 17:56:30 +0200
From:	David Sterba <dsterba@...e.cz>
To:	Omar Sandoval <osandov@...ndov.com>
Cc:	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
	David Sterba <dsterba@...e.cz>, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] Btrfs: show subvol= and subvolid= in /proc/mounts

On Tue, Apr 07, 2015 at 10:34:02PM -0700, Omar Sandoval wrote:
> Currently, userspace has no way to know which subvolume is mounted.

Oh, there is a way, 'btrfs inspect-internal rootid /path/to/mount', just
we'd like to see it in the mount options as well.

> But,
> now that we're guaranteed to have a meaningful root dentry, we can just
> export and use seq_dentry() in btrfs_show_options(). The subvolume ID is
> easy to get, so put that in there, too.
> 
> Signed-off-by: Omar Sandoval <osandov@...ndov.com>
> ---
>  fs/btrfs/super.c | 4 ++++
>  fs/seq_file.c    | 1 +
>  2 files changed, 5 insertions(+)
> 
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 5ab9801..5e14bb6 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -1193,6 +1193,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
>  		seq_puts(seq, ",fatal_errors=panic");
>  	if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
>  		seq_printf(seq, ",commit=%d", info->commit_interval);
> +	seq_puts(seq, ",subvol=");

Please make subvol= the last one, as it can contain any string that
could be confused with other options. Although nobody would probably
call their subvolume "name,autodefrag" etc, the way to obtain the full
path is to either resolve the subvolid, or take the whole text after
"subvol=" to the end of the line.

> +	seq_dentry(seq, dentry, " \t\n\\");
> +	seq_printf(seq, ",subvolid=%llu",
> +		  BTRFS_I(d_inode(dentry))->root->root_key.objectid);
>  	return 0;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/