Re: [PATCH v2 1/3] btrfs: consume the given iter directly instead of copying in csum_one_bio()

[Qu Wenruo <wqu@suse.com>]

在 2026/9/3 15:53, Daniel Vacek 写道:
> This is just a small cleanup to avoid copying the iter twice in async case.
> We already have a copy csum_one_bio() can consume directly. No need to copy
> again the second time.
> We can use this copy also in the sync case and get rid of the parameter.
> 
> Signed-off-by: Daniel Vacek <neelx@suse.com>

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

Thanks,
Qu

> ---
> 
> v2: Use the bbio::csum_saved_iter in both cases and simplify even further.
> ---
>   fs/btrfs/file-item.c | 15 +++++++--------
>   1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
> index 581ca5653be9..4a7681557ec1 100644
> --- a/fs/btrfs/file-item.c
> +++ b/fs/btrfs/file-item.c
> @@ -797,18 +797,17 @@ int btrfs_lookup_csums_bitmap(struct btrfs_root *root, struct btrfs_path *path,
>   	return ret;
>   }
>   
> -static void csum_one_bio(struct btrfs_bio *bbio, struct bvec_iter *src)
> +static void csum_one_bio(struct btrfs_bio *bbio)
>   {
>   	struct btrfs_inode *inode = bbio->inode;
>   	struct btrfs_fs_info *fs_info = inode->root->fs_info;
>   	struct btrfs_ordered_sum *sums = bbio->sums;
> -	struct bvec_iter iter;
> +	struct bvec_iter *iter = &bbio->csum_saved_iter;
>   	const u32 blocksize = fs_info->sectorsize;
>   	int index = 0;
>   
> -	for (iter = *src; iter.bi_size; bio_advance_iter(&bbio->bio, &iter, blocksize)) {
> -		btrfs_csum_one_bio_block(fs_info, &bbio->bio, &iter,
> -					 sums->sums + index);
> +	for (; iter->bi_size; bio_advance_iter(&bbio->bio, iter, blocksize)) {
> +		btrfs_csum_one_bio_block(fs_info, &bbio->bio, iter, sums->sums + index);
>   
>   		index += fs_info->csum_size;
>   	}
> @@ -820,7 +819,7 @@ static void csum_one_bio_work(struct work_struct *work)
>   
>   	ASSERT(btrfs_op(&bbio->bio) == BTRFS_MAP_WRITE);
>   	ASSERT(bbio->async_csum == true);
> -	csum_one_bio(bbio, &bbio->csum_saved_iter);
> +	csum_one_bio(bbio);
>   	complete(&bbio->csum_done);
>   }
>   
> @@ -850,13 +849,13 @@ int btrfs_csum_one_bio(struct btrfs_bio *bbio, bool async)
>   	bbio->sums = sums;
>   	btrfs_add_ordered_sum(ordered, sums);
>   
> +	bbio->csum_saved_iter = bio->bi_iter;
>   	if (!async) {
> -		csum_one_bio(bbio, &bbio->bio.bi_iter);
> +		csum_one_bio(bbio);
>   		return 0;
>   	}
>   	init_completion(&bbio->csum_done);
>   	bbio->async_csum = true;
> -	bbio->csum_saved_iter = bbio->bio.bi_iter;
>   	INIT_WORK(&bbio->csum_work, csum_one_bio_work);
>   	schedule_work(&bbio->csum_work);
>   	return 0;