Re: [PATCH 3/3] btrfs-progs: Remove convert param from btrfs_alloc_data_chunk

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

On 2019/10/30 下午8:22, Nikolay Borisov wrote:
> convert is always set to true so there's no point in having it as a
> function parameter or using it as a predicate inside btrfs_alloc_data_chunk.
> Remove it and all relevant code which would have never been executed.
> No semantics changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>

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

Just one tip for further patches.

The function btrfs_alloc_data_chunk() is purely used for convert to
create a 1:1 mapped data chunk.

It would be be even better to rename the function to indicate it better.

Thanks,
Qu

> ---
>  convert/main.c |  3 +--
>  volumes.c      | 44 ++++++++++++++------------------------------
>  volumes.h      |  3 +--
>  3 files changed, 16 insertions(+), 34 deletions(-)
>
> diff --git a/convert/main.c b/convert/main.c
> index 9904deafba45..416ab5d264a3 100644
> --- a/convert/main.c
> +++ b/convert/main.c
> @@ -942,8 +942,7 @@ static int make_convert_data_block_groups(struct btrfs_trans_handle *trans,
>
>  			len = min(max_chunk_size,
>  				  cache->start + cache->size - cur);
> -			ret = btrfs_alloc_data_chunk(trans, fs_info,
> -					&cur_backup, len, 1);
> +			ret = btrfs_alloc_data_chunk(trans, fs_info, &cur_backup, len);
>  			if (ret < 0)
>  				break;
>  			ret = btrfs_make_block_group(trans, fs_info, 0,
> diff --git a/volumes.c b/volumes.c
> index 87315a884b49..39e824a43736 100644
> --- a/volumes.c
> +++ b/volumes.c
> @@ -1238,14 +1238,11 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
>  /*
>   * Alloc a DATA chunk with SINGLE profile.
>   *
> - * If 'convert' is set, it will alloc a chunk with 1:1 mapping
> - * (btrfs logical bytenr == on-disk bytenr)
> - * For that case, caller must make sure the chunk and dev_extent are not
> - * occupied.
> + * It allocates a chunk with 1:1 mapping (btrfs logical bytenr == on-disk bytenr)
> + * Caller must make sure the chunk and dev_extent are not occupied.
>   */
>  int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
> -			   struct btrfs_fs_info *info, u64 *start,
> -			   u64 num_bytes, int convert)
> +			   struct btrfs_fs_info *info, u64 *start, u64 num_bytes)
>  {
>  	u64 dev_offset;
>  	struct btrfs_root *extent_root = info->extent_root;
> @@ -1264,25 +1261,18 @@ int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
>  	int stripe_len = BTRFS_STRIPE_LEN;
>  	struct btrfs_key key;
>
> -	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
> -	key.type = BTRFS_CHUNK_ITEM_KEY;
> -	if (convert) {
> -		if (*start != round_down(*start, info->sectorsize)) {
> -			error("DATA chunk start not sectorsize aligned: %llu",
> -					(unsigned long long)*start);
> -			return -EINVAL;
> -		}
> -		key.offset = *start;
> -		dev_offset = *start;
> -	} else {
> -		u64 tmp;
>
> -		ret = find_next_chunk(info, &tmp);
> -		key.offset = tmp;
> -		if (ret)
> -			return ret;
> +	if (*start != round_down(*start, info->sectorsize)) {
> +		error("DATA chunk start not sectorsize aligned: %llu",
> +				(unsigned long long)*start);
> +		return -EINVAL;
>  	}
>
> +	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
> +	key.type = BTRFS_CHUNK_ITEM_KEY;
> +	key.offset = *start;
> +	dev_offset = *start;
> +
>  	chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
>  	if (!chunk)
>  		return -ENOMEM;
> @@ -1303,12 +1293,8 @@ int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
>  	while (index < num_stripes) {
>  		struct btrfs_stripe *stripe;
>
> -		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);
> +		ret = btrfs_insert_dev_extent(trans, device, key.offset, calc_size,
> +				dev_offset);
>  		BUG_ON(ret);
>
>  		device->bytes_used += calc_size;
> @@ -1345,8 +1331,6 @@ int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
>  	ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
>  				btrfs_chunk_item_size(num_stripes));
>  	BUG_ON(ret);
> -	if (!convert)
> -		*start = key.offset;
>
>  	map->ce.start = key.offset;
>  	map->ce.size = num_bytes;
> diff --git a/volumes.h b/volumes.h
> index 83ba827e422b..f6f05054b5c4 100644
> --- a/volumes.h
> +++ b/volumes.h
> @@ -271,8 +271,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
>  		      struct btrfs_fs_info *fs_info, u64 *start,
>  		      u64 *num_bytes, u64 type);
>  int btrfs_alloc_data_chunk(struct btrfs_trans_handle *trans,
> -			   struct btrfs_fs_info *fs_info, u64 *start,
> -			   u64 num_bytes, int convert);
> +			   struct btrfs_fs_info *fs_info, u64 *start, u64 num_bytes);
>  int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
>  		       int flags);
>  int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
>