Re: [PATCH 1/6] sysfs: Basic support for multiple super blocks

["Serge E. Hallyn" <serue@us.ibm.com>]

Quoting Eric W. Biederman (ebiederm@xmission.com):
> From: Eric W. Biederman <ebiederm@xmission.com>
> 
> Add all of the necessary bioler plate to support
> multiple superblocks in sysfs.
> 
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Acked-by: Serge Hallyn <serue@us.ibm.com>

> ---
>  fs/sysfs/mount.c |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  fs/sysfs/sysfs.h |    3 ++
>  2 files changed, 59 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
> index 0cb1088..6a433ac 100644
> --- a/fs/sysfs/mount.c
> +++ b/fs/sysfs/mount.c
> @@ -71,16 +71,70 @@ static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
>  	return 0;
>  }
> 
> +static int sysfs_test_super(struct super_block *sb, void *data)
> +{
> +	struct sysfs_super_info *sb_info = sysfs_info(sb);
> +	struct sysfs_super_info *info = data;
> +	int found = 1;
> +	return found;
> +}
> +
> +static int sysfs_set_super(struct super_block *sb, void *data)
> +{
> +	int error;
> +	error = set_anon_super(sb, data);
> +	if (!error)
> +		sb->s_fs_info = data;
> +	return error;
> +}
> +
>  static int sysfs_get_sb(struct file_system_type *fs_type,
>  	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
>  {
> -	return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
> +	struct sysfs_super_info *info;
> +	struct super_block *sb;
> +	int error;
> +
> +	error = -ENOMEM;
> +	info = kzalloc(sizeof(*info), GFP_KERNEL);
> +	if (!info)
> +		goto out;
> +	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
> +	if (IS_ERR(sb) || sb->s_fs_info != info)
> +		kfree(info);
> +	if (IS_ERR(sb)) {
> +		kfree(info);
> +		error = PTR_ERR(sb);
> +		goto out;
> +	}
> +	if (!sb->s_root) {
> +		sb->s_flags = flags;
> +		error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
> +		if (error) {
> +			deactivate_locked_super(sb);
> +			goto out;
> +		}
> +		sb->s_flags |= MS_ACTIVE;
> +	}
> +
> +	simple_set_mnt(mnt, sb);
> +	error = 0;
> +out:
> +	return error;
> +}
> +
> +static void sysfs_kill_sb(struct super_block *sb)
> +{
> +	struct sysfs_super_info *info = sysfs_info(sb);
> +
> +	kill_anon_super(sb);
> +	kfree(info);
>  }
> 
>  static struct file_system_type sysfs_fs_type = {
>  	.name		= "sysfs",
>  	.get_sb		= sysfs_get_sb,
> -	.kill_sb	= kill_anon_super,
> +	.kill_sb	= sysfs_kill_sb,
>  };
> 
>  int __init sysfs_init(void)
> diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
> index 30f5a44..030a39d 100644
> --- a/fs/sysfs/sysfs.h
> +++ b/fs/sysfs/sysfs.h
> @@ -114,6 +114,9 @@ struct sysfs_addrm_cxt {
>  /*
>   * mount.c
>   */
> +struct sysfs_super_info {
> +};
> +#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
>  extern struct sysfs_dirent sysfs_root;
>  extern struct kmem_cache *sysfs_dir_cachep;
> 
> -- 
> 1.6.5.2.143.g8cc62