Re: [PATCH] Btrfs: Add get/set label ioctl

[Jie Liu <jeff.liu@oracle.com>]

Hi Anand,

I have posted a patch for set label back to last year, which can be
found at:
https://patchwork.kernel.org/patch/1124642/

Besides that,  we have discussed to use 50 as the ioctl(2) number at
that time.

task assignment in our wiki page:
https://btrfs.wiki.kernel.org/index.php/Project_ideas#Set.2Fchange_file_system_label

Thanks,
-Jeff

On 08/29/12 16:46, Anand jain wrote:
> From: Anand Jain <anand.jain@oracle.com>
>
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/ctree.h |   10 ++++++++++
>  fs/btrfs/ioctl.c |   30 ++++++++++++++++++++++++++++++
>  fs/btrfs/ioctl.h |    2 ++
>  3 files changed, 42 insertions(+), 0 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 4bab807..eff506f 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -2583,6 +2583,16 @@ BTRFS_SETGET_STACK_FUNCS(super_csum_type, struct btrfs_super_block,
>  BTRFS_SETGET_STACK_FUNCS(super_cache_generation, struct btrfs_super_block,
>  			 cache_generation, 64);
>  
> +static inline char * btrfs_super_label(struct btrfs_super_block *s)
> +{
> +	return s->label;
> +}
> +static inline void btrfs_set_super_label(struct btrfs_super_block *s,
> +	char *val)
> +{
> +	memcpy(s->label,val,BTRFS_LABEL_SIZE);
> +}
> +
>  static inline int btrfs_super_csum_size(struct btrfs_super_block *s)
>  {
>  	int t = btrfs_super_csum_type(s);
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 7bb7556..b472942 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3687,6 +3687,32 @@ out:
>  	return ret;
>  }
>  
> +static int btrfs_ioctl_get_label(struct btrfs_root *root, void __user *arg)
> +{
> +	char *label;
> +	label = btrfs_super_label(root->fs_info->super_copy);
> +	if (copy_to_user(arg, label, BTRFS_LABEL_SIZE))
> +		return -EFAULT;
> +	return 0;
> +}
> +
> +static int btrfs_ioctl_set_label(struct btrfs_root *root, void __user *arg)
> +{
> +	struct btrfs_trans_handle *trans;
> +	char label[BTRFS_LABEL_SIZE+1];
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +	if (copy_from_user(label, arg, BTRFS_LABEL_SIZE))
> +		return -EFAULT;
> +	label[BTRFS_LABEL_SIZE] = '\0';
> +	trans = btrfs_start_transaction(root, 1);
> +	btrfs_set_super_label(root->fs_info->super_copy, label);
> +	btrfs_commit_transaction(trans, root);
> +
> +	return 0;
> +}
> +
>  long btrfs_ioctl(struct file *file, unsigned int
>  		cmd, unsigned long arg)
>  {
> @@ -3785,6 +3811,10 @@ long btrfs_ioctl(struct file *file, unsigned int
>  		return btrfs_ioctl_qgroup_create(root, argp);
>  	case BTRFS_IOC_QGROUP_LIMIT:
>  		return btrfs_ioctl_qgroup_limit(root, argp);
> +	case BTRFS_IOC_GET_LABEL:
> +		return btrfs_ioctl_get_label(root, argp);
> +	case BTRFS_IOC_SET_LABEL:
> +		return btrfs_ioctl_set_label(root, argp);
>  	}
>  
>  	return -ENOTTY;
> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
> index 731e287..0c60fcb 100644
> --- a/fs/btrfs/ioctl.h
> +++ b/fs/btrfs/ioctl.h
> @@ -453,4 +453,6 @@ struct btrfs_ioctl_send_args {
>  			       struct btrfs_ioctl_qgroup_limit_args)
>  #define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
>  				      struct btrfs_ioctl_get_dev_stats)
> +#define BTRFS_IOC_GET_LABEL _IOR(BTRFS_IOCTL_MAGIC, 53, __u64)
> +#define BTRFS_IOC_SET_LABEL _IOW(BTRFS_IOCTL_MAGIC, 54, __u64)
>  #endif