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Date:   Thu, 4 Oct 2018 12:02:20 +0200
From:   David Sterba <dsterba@suse.cz>
To:     zhong jiang <zhongjiang@huawei.com>
Cc:     dsterba@suse.cz, osandov@osandov.com, dsterba@suse.com,
        jbacik@fb.com, clm@fb.com, linux-btrfs@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2] btrfs: list usage cleanup
Message-ID: <20181004100220.GA29418@twin.jikos.cz>
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On Thu, Oct 04, 2018 at 12:48:27PM +0800, zhong jiang wrote:
> Trival cleanup, list_move_tail will implement the same function that
> list_del() + list_add_tail() will do. hence just replace them.
> 
> Signed-off-by: zhong jiang <zhongjiang@huawei.com>
> ---
>  fs/btrfs/send.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
> index 094cc144..30e7e12 100644
> --- a/fs/btrfs/send.c
> +++ b/fs/btrfs/send.c
> @@ -2075,8 +2075,8 @@ static struct name_cache_entry *name_cache_search(struct send_ctx *sctx,
>   */
>  static void name_cache_used(struct send_ctx *sctx, struct name_cache_entry *nce)
>  {
> -	list_del(&nce->list);
> -	list_add_tail(&nce->list, &sctx->name_cache_list);
> +	/* delete from sctx->name_cache_list and add as its tail */
> +	list_move_tail(&nce->list, &sctx->name_cache_list);

The suggestion was to drop name_cache_used and replace it with
list_move_tail(...), the comment as you wrote it does not bring much
information as it merely repeats how list_move_tail is implemeted. A
useful comment explains something that's not obvious.