Re: [PATCH v2 3/5] btrfs-progs: volumes: Refactor btrfs_alloc_dev_extent() into two functions

[Nikolay Borisov <nborisov@suse.com>]

On 27.11.18 г. 10:38 ч., Qu Wenruo wrote:
> We have btrfs_alloc_dev_extent() accepting @convert flag to toggle
> special handling for convert.
> 
> However that @convert flag only determine whether we call
> find_free_dev_extent(), and we may later need to insert dev extents
> without searching dev tree.
> 
> So refactor btrfs_alloc_dev_extent() into 2 functions,
> btrfs_alloc_dev_extent(), which will try to find free dev extent, and
> btrfs_insert_dev_extent(), which will just insert a dev extent.
> 
> For implementation, btrfs_alloc_dev_extent() will call
> btrfs_insert_dev_extent() anyway, so no duplicated code.
> 
> This removes the need of @convert parameter, and make
> btrfs_insert_dev_extent() public for later usage.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

This looks much better:

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  volumes.c | 48 ++++++++++++++++++++++++++++++------------------
>  volumes.h |  3 +++
>  2 files changed, 33 insertions(+), 18 deletions(-)
> 
> diff --git a/volumes.c b/volumes.c
> index 30090ce5f8e8..0dd082cd1718 100644
> --- a/volumes.c
> +++ b/volumes.c
> @@ -530,10 +530,12 @@ static int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
>  	return find_free_dev_extent_start(device, num_bytes, 0, start, len);
>  }
>  
> -static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
> -				  struct btrfs_device *device,
> -				  u64 chunk_offset, u64 num_bytes, u64 *start,
> -				  int convert)
> +/*
> + * Insert one device extent into the fs.
> + */
> +int btrfs_insert_dev_extent(struct btrfs_trans_handle *trans,
> +			    struct btrfs_device *device,
> +			    u64 chunk_offset, u64 num_bytes, u64 start)
>  {
>  	int ret;
>  	struct btrfs_path *path;
> @@ -546,18 +548,8 @@ static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
>  	if (!path)
>  		return -ENOMEM;
>  
> -	/*
> -	 * For convert case, just skip search free dev_extent, as caller
> -	 * is responsible to make sure it's free.
> -	 */
> -	if (!convert) {
> -		ret = find_free_dev_extent(device, num_bytes, start, NULL);
> -		if (ret)
> -			goto err;
> -	}
> -
>  	key.objectid = device->devid;
> -	key.offset = *start;
> +	key.offset = start;
>  	key.type = BTRFS_DEV_EXTENT_KEY;
>  	ret = btrfs_insert_empty_item(trans, root, path, &key,
>  				      sizeof(*extent));
> @@ -583,6 +575,22 @@ err:
>  	return ret;
>  }
>  
> +/*
> + * Allocate one free dev extent and insert it into the fs.
> + */
> +static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
> +				  struct btrfs_device *device,
> +				  u64 chunk_offset, u64 num_bytes, u64 *start)
> +{
> +	int ret;
> +
> +	ret = find_free_dev_extent(device, num_bytes, start, NULL);
> +	if (ret)
> +		return ret;
> +	return btrfs_insert_dev_extent(trans, device, chunk_offset, num_bytes,
> +					*start);
> +}
> +
>  static int find_next_chunk(struct btrfs_fs_info *fs_info, u64 *offset)
>  {
>  	struct btrfs_root *root = fs_info->chunk_root;
> @@ -1107,7 +1115,7 @@ again:
>  			list_move_tail(&device->dev_list, dev_list);
>  
>  		ret = btrfs_alloc_dev_extent(trans, device, key.offset,
> -			     calc_size, &dev_offset, 0);
> +			     calc_size, &dev_offset);
>  		if (ret < 0)
>  			goto out_chunk_map;
>  
> @@ -1241,8 +1249,12 @@ int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
>  	while (index < num_stripes) {
>  		struct btrfs_stripe *stripe;
>  
> -		ret = btrfs_alloc_dev_extent(trans, device, key.offset,
> -			     calc_size, &dev_offset, convert);
> +		if (convert)
> +			ret = btrfs_insert_dev_extent(trans, device, key.offset,
> +					calc_size, dev_offset);
> +		else
> +			ret = btrfs_alloc_dev_extent(trans, device, key.offset,
> +					calc_size, &dev_offset);
>  		BUG_ON(ret);
>  
>  		device->bytes_used += calc_size;
> diff --git a/volumes.h b/volumes.h
> index b4ea93f0bec3..44284ee75adb 100644
> --- a/volumes.h
> +++ b/volumes.h
> @@ -268,6 +268,9 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
>  		       int flags);
>  int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
>  void btrfs_close_all_devices(void);
> +int btrfs_insert_dev_extent(struct btrfs_trans_handle *trans,
> +			    struct btrfs_device *device,
> +			    u64 chunk_offset, u64 num_bytes, u64 start);
>  int btrfs_add_device(struct btrfs_trans_handle *trans,
>  		     struct btrfs_fs_info *fs_info,
>  		     struct btrfs_device *device);
>