On 12/28/2012 08:03 PM, David Sterba wrote:
> On Fri, Dec 28, 2012 at 11:42:40AM +0800, Jeff Liu wrote:
>> +static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
>> +{
>> + struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
>> + struct btrfs_super_block *super_block = root->fs_info->super_copy;
>> + struct btrfs_trans_handle *trans;
>> + char label[BTRFS_LABEL_SIZE];
>> + int ret;
>> +
>> + if (!capable(CAP_SYS_ADMIN))
>> + return -EPERM;
>> +
>> + if (copy_from_user(label, arg, sizeof(label)))
>> + return -EFAULT;
>> +
>> + if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE)
>
> I would expect a message if this happens, similar to the 'get_fslabel'
> one, otherwise it's difficult to find out the reason.
That's sounds make sense.
>
>> + return -EINVAL;
>> +
>> + ret = mnt_want_write_file(file);
>> + if (ret)
>> + return ret;
>> +
>> + mutex_lock(&root->fs_info->volume_mutex);
>> + trans = btrfs_start_transaction(root, 1);
>
> Do we need to reserve 1 unit here? This does not touch any
> non-superblock metadata, modifies superblock in place. This could lead
> to an ENOSPC (changing label on a full fs), altghouh it need not happen.
Don't need, I can not recalled why I did that before, will fix it.
Thanks,
-Jeff
>
>> + if (IS_ERR(trans)) {
>> + ret = PTR_ERR(trans);
>> + goto out_unlock;
>> + }
>> +
>> + strcpy(super_block->label, label);
>> + ret = btrfs_end_transaction(trans, root);
>> +
>> +out_unlock:
>> + mutex_unlock(&root->fs_info->volume_mutex);
>> + mnt_drop_write_file(file);
>> + return ret;
>> +}
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