Re: [PATCH 1/3] btrfs: Make btrfs_find_device_by_path return struct btrfs_device

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2018/9/3 下午5:46, Nikolay Borisov wrote:
> Currently this function returns an error code as well as uses one of
> its arguments as a return value for struct btrfs_device. Change the
> function so that it returns btrfs_device directly and use the usual
> "encode error in pointer" mechanics if something goes wrong. No
> functional changes.
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> ---
>  fs/btrfs/volumes.c | 26 ++++++++++++++------------
>  1 file changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index da86706123ff..715ea45c6c28 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -2096,9 +2096,9 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
>  	call_rcu(&tgtdev->rcu, free_device_rcu);
>  }
>  
> -static int btrfs_find_device_by_path(struct btrfs_fs_info *fs_info,
> -				     const char *device_path,
> -				     struct btrfs_device **device)
> +static struct btrfs_device *
> +btrfs_find_device_by_path(struct btrfs_fs_info *fs_info,
> +			  const char *device_path)
>  {
>  	int ret = 0;
>  	struct btrfs_super_block *disk_super;
> @@ -2106,21 +2106,21 @@ static int btrfs_find_device_by_path(struct btrfs_fs_info *fs_info,
>  	u8 *dev_uuid;
>  	struct block_device *bdev;
>  	struct buffer_head *bh;
> +	struct btrfs_device *device;
>  
> -	*device = NULL;
>  	ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ,
>  				    fs_info->bdev_holder, 0, &bdev, &bh);
>  	if (ret)
> -		return ret;
> +		return ERR_PTR(ret);
>  	disk_super = (struct btrfs_super_block *)bh->b_data;
>  	devid = btrfs_stack_device_id(&disk_super->dev_item);
>  	dev_uuid = disk_super->dev_item.uuid;
> -	*device = btrfs_find_device(fs_info, devid, dev_uuid, disk_super->fsid);
> +	device = btrfs_find_device(fs_info, devid, dev_uuid, disk_super->fsid);
>  	brelse(bh);
> -	if (!*device)
> -		ret = -ENOENT;
> +	if (!device)
> +		device = ERR_PTR(-ENOENT);
>  	blkdev_put(bdev, FMODE_READ);
> -	return ret;
> +	return device;
>  }
>  
>  int btrfs_find_device_missing_or_by_path(struct btrfs_fs_info *fs_info,
> @@ -2143,11 +2143,13 @@ int btrfs_find_device_missing_or_by_path(struct btrfs_fs_info *fs_info,
>  
>  		if (!*device)
>  			return BTRFS_ERROR_DEV_MISSING_NOT_FOUND;
> -
> -		return 0;
>  	} else {
> -		return btrfs_find_device_by_path(fs_info, device_path, device);
> +		*device = btrfs_find_device_by_path(fs_info, device_path);
> +		if (IS_ERR(*device))
> +			return PTR_ERR(*device);
>  	}
> +
> +	return 0;
>  }
>  
>  /*
>