linux-kernel - Re: [PATCH 3/3] f2fs: avoid reading NAT page by get_node

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Message-ID: <c911629f-7c6c-00d3-3d94-8c6a9a5fb0ca@huawei.com>
Date:   Thu, 23 Feb 2017 19:47:29 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [PATCH 3/3] f2fs: avoid reading NAT page by get_node_info

On 2017/2/14 10:06, Jaegeuk Kim wrote:
> We've not seen this buggy case for a long time, so it's time to avoid this
> unnecessary get_node_info() call which reading NAT page to cache nat entry.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  fs/f2fs/node.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index e001d084667f..b63bdb85ad66 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1033,7 +1033,7 @@ struct page *new_node_page(struct dnode_of_data *dn,
>  				unsigned int ofs, struct page *ipage)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
> -	struct node_info old_ni, new_ni;
> +	struct node_info new_ni;
>  	struct page *page;
>  	int err;
>  
> @@ -1049,12 +1049,11 @@ struct page *new_node_page(struct dnode_of_data *dn,
>  		goto fail;
>  	}
>  
> -	get_node_info(sbi, dn->nid, &old_ni);
> -
> -	/* Reinitialize old_ni with new node page */
> -	f2fs_bug_on(sbi, old_ni.blk_addr != NULL_ADDR);

What about keeping get_node_info covered with CONFIG_F2FS_CHECK_FS for
consistence as we just introduce two new free nid caches, I think it will be
helpful for detecting bugs of these new codes.

Thanks,

> -	new_ni = old_ni;
> +	new_ni.nid = dn->nid;
>  	new_ni.ino = dn->inode->i_ino;
> +	new_ni.blk_addr = NULL_ADDR;
> +	new_ni.flag = 0;
> +	new_ni.version = 0;
>  	set_node_addr(sbi, &new_ni, NEW_ADDR, false);
>  
>  	f2fs_wait_on_page_writeback(page, NODE, true);
>