Re: [PATCH 5/9] btrfs-progs: add helper for writing empty tree nodes

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

On 2021/8/21 上午3:11, Josef Bacik wrote:
> With extent tree v2 we're going to be writing some more empty trees for
> the initial mkfs step, so take this common code and make it a helper.
>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

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

Just a small nitpick on the function naming inliend below.

> ---
>   mkfs/common.c | 47 +++++++++++++++++++++++++----------------------
>   1 file changed, 25 insertions(+), 22 deletions(-)
>
> diff --git a/mkfs/common.c b/mkfs/common.c
> index 29fc8f12..9263965e 100644
> --- a/mkfs/common.c
> +++ b/mkfs/common.c
> @@ -39,6 +39,25 @@ static u64 reference_root_table[] = {
>   	[MKFS_CSUM_TREE]	=	BTRFS_CSUM_TREE_OBJECTID,
>   };
>
> +static int btrfs_write_empty_tree(int fd, struct btrfs_mkfs_config *cfg,
> +				  struct extent_buffer *buf, u64 objectid,
> +				  u64 block)

Can't we replace the btrfs prefix?

This function is specific to mkfs, and it only works for the initial
btrfs creation.

Thanks,
Qu

> +{
> +	int ret;
> +
> +	memset(buf->data + sizeof(struct btrfs_header), 0,
> +		cfg->nodesize - sizeof(struct btrfs_header));
> +	btrfs_set_header_bytenr(buf, block);
> +	btrfs_set_header_owner(buf, objectid);
> +	btrfs_set_header_nritems(buf, 0);
> +	csum_tree_block_size(buf, btrfs_csum_type_size(cfg->csum_type), 0,
> +			     cfg->csum_type);
> +	ret = pwrite(fd, buf->data, cfg->nodesize, block);
> +	if (ret != cfg->nodesize)
> +		return ret < 0 ? -errno : -EIO;
> +	return 0;
> +}
> +
>   static int btrfs_create_tree_root(int fd, struct btrfs_mkfs_config *cfg,
>   				  struct extent_buffer *buf,
>   				  const enum btrfs_mkfs_block *blocks,
> @@ -460,31 +479,15 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
>   	}
>
>   	/* create the FS root */
> -	memset(buf->data + sizeof(struct btrfs_header), 0,
> -		cfg->nodesize - sizeof(struct btrfs_header));
> -	btrfs_set_header_bytenr(buf, cfg->blocks[MKFS_FS_TREE]);
> -	btrfs_set_header_owner(buf, BTRFS_FS_TREE_OBJECTID);
> -	btrfs_set_header_nritems(buf, 0);
> -	csum_tree_block_size(buf, btrfs_csum_type_size(cfg->csum_type), 0,
> -			     cfg->csum_type);
> -	ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[MKFS_FS_TREE]);
> -	if (ret != cfg->nodesize) {
> -		ret = (ret < 0 ? -errno : -EIO);
> +	ret = btrfs_write_empty_tree(fd, cfg, buf, BTRFS_FS_TREE_OBJECTID,
> +				     cfg->blocks[MKFS_FS_TREE]);
> +	if (ret)
>   		goto out;
> -	}
>   	/* finally create the csum root */
> -	memset(buf->data + sizeof(struct btrfs_header), 0,
> -		cfg->nodesize - sizeof(struct btrfs_header));
> -	btrfs_set_header_bytenr(buf, cfg->blocks[MKFS_CSUM_TREE]);
> -	btrfs_set_header_owner(buf, BTRFS_CSUM_TREE_OBJECTID);
> -	btrfs_set_header_nritems(buf, 0);
> -	csum_tree_block_size(buf, btrfs_csum_type_size(cfg->csum_type), 0,
> -			     cfg->csum_type);
> -	ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[MKFS_CSUM_TREE]);
> -	if (ret != cfg->nodesize) {
> -		ret = (ret < 0 ? -errno : -EIO);
> +	ret = btrfs_write_empty_tree(fd, cfg, buf, BTRFS_CSUM_TREE_OBJECTID,
> +				     cfg->blocks[MKFS_CSUM_TREE]);
> +	if (ret)
>   		goto out;
> -	}
>
>   	/* and write out the super block */
>   	memset(buf->data, 0, BTRFS_SUPER_INFO_SIZE);
>