linux-kernel - Re: [PATCH] f2fs: optimize alloc_nid

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Date:	Mon, 6 May 2013 21:20:10 +0800
From:	Haicheng Li <haicheng.li@...ux.intel.com>
To:	linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	Jaegeuk Kim <jaegeuk.kim@...sung.com>
Cc:	huajun.li@...el.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: optimize alloc_nid_failed()

Just realized I should develop the patches against Kim's f2fs-dev branch
rather than the f2fs-master branch. (thanks to Huajun for the reminding).

Obviously on f2fs-dev branch, some optimizations of alloc_nid_failed() have
already been done.

Pls. ignore this patch, I'll send out the rebased version of my recent f2fs
patches soon later, which will be based on the f2fs-dev tree.

On Mon, May 06, 2013 at 07:25:06PM +0800, Haicheng Li wrote:
> Current alloc_nid_failed() has two issues:
> 1. unecessarily kmem_cache_free() the free_nid and then realloc a new
>    slab cache for it immediately;
> 2. needs to __lookup_free_nid_list() twice in order to find out the free_nid
>    from free_nid_list.
> 
> This patch fixes these issues.
> 
> Signed-off-by: Haicheng Li <haicheng.li@...ux.intel.com>
> ---
>  fs/f2fs/node.c |   17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index e275218..7ce8e9f 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1403,8 +1403,21 @@ void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid)
>   */
>  void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
>  {
> -	alloc_nid_done(sbi, nid);
> -	add_free_nid(NM_I(sbi), nid);
> +	struct f2fs_nm_info *nm_i = NM_I(sbi);
> +	struct free_nid *i;
> +
> +	spin_lock(&nm_i->free_nid_list_lock);
> +	i = __lookup_free_nid_list(nid, &nm_i->free_nid_list);
> +	if (i) {
> +		BUG_ON(i->state != NID_ALLOC);
> +		if (nm_i->fcnt > 2 * MAX_FREE_NIDS)
> +			__del_from_free_nid_list(i);
> +		else {
> +			i->state = NID_NEW;
> +			nm_i->fcnt++;
> +		}
> +	}
> +	spin_unlock(&nm_i->free_nid_list_lock);
>  }
>  
>  void recover_node_page(struct f2fs_sb_info *sbi, struct page *page,
> -- 
> 1.7.9.5
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