Re: [PATCH 5/7] btrfs-progs: backref: add list_first_pref helper

[Nikolay Borisov <nborisov@suse.com>]

On 25.07.2017 23:51, jeffm@suse.com wrote:
> From: Jeff Mahoney <jeffm@suse.com>
> 
> ---
>  backref.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/backref.c b/backref.c
> index ac1b506..be3376a 100644
> --- a/backref.c
> +++ b/backref.c
> @@ -130,6 +130,11 @@ struct __prelim_ref {
>  	u64 wanted_disk_byte;
>  };
>  
> +static struct __prelim_ref *list_first_pref(struct list_head *head)
> +{
> +	return list_first_entry(head, struct __prelim_ref, list);
> +}
> +

I think this just adds one more level of abstraction with no real
benefit whatsoever. Why not drop the patch entirely.

>  struct pref_state {
>  	struct list_head pending;
>  };
> @@ -804,8 +809,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
>  	__merge_refs(&prefstate, 2);
>  
>  	while (!list_empty(&prefstate.pending)) {
> -		ref = list_first_entry(&prefstate.pending,
> -				       struct __prelim_ref, list);
> +		ref = list_first_pref(&prefstate.pending);
>  		WARN_ON(ref->count < 0);
>  		if (roots && ref->count && ref->root_id && ref->parent == 0) {
>  			/* no parent == root of tree */
> @@ -857,8 +861,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
>  out:
>  	btrfs_free_path(path);
>  	while (!list_empty(&prefstate.pending)) {
> -		ref = list_first_entry(&prefstate.pending,
> -				       struct __prelim_ref, list);
> +		ref = list_first_pref(&prefstate.pending);
>  		list_del(&ref->list);
>  		kfree(ref);
>  	}
>