Hi, Anand
On fri, 16 Nov 2012 12:52:25 +0800, Anand jain wrote:
> +static int btrfs_ioctl_subvol_getlabel(struct btrfs_root *root,
> + void __user *arg)
> +{
> + char *label;
> +
> + label = btrfs_root_label(&root->root_item);
> + if (copy_to_user(arg, label, BTRFS_SUBVOL_LABEL_SIZE))
> + return -EFAULT;
> + return 0;
> +}
> +
> +static int btrfs_ioctl_subvol_setlabel(struct btrfs_root *root,
> + void __user *arg)
> +{
> + char label[BTRFS_SUBVOL_LABEL_SIZE+1];
> + struct btrfs_trans_handle *trans;
> +
> + if (copy_from_user(label, arg, BTRFS_SUBVOL_LABEL_SIZE))
> + return -EFAULT;
> + trans = btrfs_join_transaction(root);
> + if (IS_ERR(trans))
> + return PTR_ERR(trans);
> + btrfs_root_set_label(&root->root_item, label);
> + btrfs_end_transaction(trans, root);
We need a lock to protect the label, and besides that, we need to get the write
access before we set the label for the subvolume.
Thanks
Miao
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