Re: [PATCH 2/3] btrfs: backref: Implement btrfs_backref_iterator_next()

[Qu Wenruo <wqu@suse.com>]

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On 2020/2/14 下午2:33, Qu Wenruo wrote:
> This function will go next inline/keyed backref for
> btrfs_backref_iterator infrastructure.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>  fs/btrfs/backref.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index 73c4829609c9..0f231cd69675 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -2310,3 +2310,51 @@ int btrfs_backref_iterator_start(struct btrfs_backref_iterator *iterator,
>  	btrfs_release_path(path);
>  	return ret;
>  }
> +
> +int btrfs_backref_iterator_next(struct btrfs_backref_iterator *iterator)
> +{
> +	struct extent_buffer *eb = btrfs_backref_get_eb(iterator);
> +	struct btrfs_path *path = iterator->path;
> +	struct btrfs_extent_inline_ref *iref;
> +	int ret;
> +	u32 size;
> +
> +	if (iterator->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
> +	    iterator->cur_key.type == BTRFS_METADATA_ITEM_KEY) {
> +		/* We're still inside the inline refs */
> +		if (btrfs_backref_has_tree_block_info(iterator)) {
> +			/* First tree block info */
> +			size = sizeof(struct btrfs_tree_block_info);
> +		} else {
> +			/* Use inline ref type to determine the size */
> +			int type;
> +
> +			iref = (struct btrfs_extent_inline_ref *)
> +				(iterator->cur_ptr);
> +			type = btrfs_extent_inline_ref_offset(eb, iref);

Oh, I'm blindly complete the function name without checking the last word.

> +
> +			size = btrfs_extent_inline_ref_size(type);
> +		}
> +		iterator->cur_ptr += size;
> +		if (iterator->cur_ptr < iterator->end_ptr)
> +			return 0;
> +
> +		/* All inline items iterated, fall through */
> +	}
> +	/* We're at keyed items, there is no inline item, just go next item */
> +	ret = btrfs_next_item(iterator->fs_info->extent_root, iterator->path);
> +	if (ret > 0 || ret < 0)
> +		return ret;
> +
> +	btrfs_item_key_to_cpu(path->nodes[0], &iterator->cur_key,
> +			      path->slots[0]);
> +	if (iterator->cur_key.objectid != iterator->bytenr ||
> +	    (iterator->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
> +	     iterator->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
> +		return 1;
> +	iterator->item_ptr = btrfs_item_ptr_offset(path->nodes[0],
> +						   path->slots[0]);
> +	iterator->cur_ptr = iterator->item_ptr;
> +	iterator->end_ptr = btrfs_item_end_nr(path->nodes[0], path->slots[0]);
> +	return 0;
> +}
> 


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