linux-kernel - Re: [f2fs-dev] [PATCH 3/3 V3] f2fs: introduce f2fs_cache_node_page() to add page into node

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Message-id: <1386576057.2101.106.camel@kjgkr>
Date:	Mon, 09 Dec 2013 17:00:57 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Chao Yu <chao2.yu@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 3/3 V3] f2fs: introduce f2fs_cache_node_page()
 to add page into node_inode cache

Hi,

Sorry for the noise.
Once I tested this patch, I recognized that I made a mistake:

f2fs_fill_super()
 1. build_segment_manager()
    -> restore_node_summary()
       -> NULL pointer exception, due to no NAT cache.
 2. build_node_manager()

So, we should not call get_node_info() prior to build_node_manager().
And, it's not easy to change the order of build_*_manager simply.

Let's consider in more details.
Thanks,

2013-12-09 (월), 13:35 +0800, Chao Yu:
> This patch introduces f2fs_cache_node_page(), in this function, page which is
> readed ahead will be copy to node_inode's mapping cache.
> It will avoid rereading these node pages.
> 
> change log:
>  o check validity of page by searching NAT suggested by Jaegeuk Kim.
>  o add 'unlikely' for compiler optimization suggested by Jaegeuk Kim.
> 
> Suggested-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> ---
>  fs/f2fs/node.c |   39 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 099f06f..4c6da98 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1600,13 +1600,46 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages,
>  	return 0;
>  }
>  
> +/*
> + * f2fs_cache_node_page() check validaty of input page by searching NAT.
> + * Then, it will copy updated data of vaild page to node_inode cache.
> + */
> +void f2fs_cache_node_page(struct f2fs_sb_info *sbi, struct page *page,
> +						nid_t nid, block_t blkaddr)
> +{
> +	struct address_space *mapping = sbi->node_inode->i_mapping;
> +	struct page *npage;
> +	struct node_info ni;
> +
> +	get_node_info(sbi, nid, &ni);
> +
> +	if (ni.blk_addr != blkaddr)
> +		return;
> +
> +	npage = grab_cache_page(mapping, nid);
> +	if (unlikely(!npage))
> +		return;
> +
> +	if (PageUptodate(npage)) {
> +		f2fs_put_page(npage, 1);
> +		return;
> +	}
> +
> +	memcpy(page_address(npage), page_address(page), PAGE_CACHE_SIZE);
> +
> +	SetPageUptodate(npage);
> +	f2fs_put_page(npage, 1);
> +
> +	return;
> +}
> +
>  int restore_node_summary(struct f2fs_sb_info *sbi,
>  			unsigned int segno, struct f2fs_summary_block *sum)
>  {
>  	struct f2fs_node *rn;
>  	struct f2fs_summary *sum_entry;
>  	struct page *page, *tmp;
> -	block_t addr;
> +	block_t addr, blkaddr;
>  	int bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
>  	int i, last_offset, nrpages, err = 0;
>  	LIST_HEAD(page_list);
> @@ -1624,6 +1657,7 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
>  		if (err)
>  			return err;
>  
> +		blkaddr = addr;
>  		list_for_each_entry_safe(page, tmp, &page_list, lru) {
>  
>  			lock_page(page);
> @@ -1633,6 +1667,8 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
>  				sum_entry->version = 0;
>  				sum_entry->ofs_in_node = 0;
>  				sum_entry++;
> +				f2fs_cache_node_page(sbi, page,
> +					le32_to_cpu(rn->footer.nid), blkaddr);
>  			} else {
>  				err = -EIO;
>  			}
> @@ -1640,6 +1676,7 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
>  			list_del(&page->lru);
>  			unlock_page(page);
>  			__free_pages(page, 0);
> +			blkaddr++;
>  		}
>  	}
>  	return err;

-- 
Jaegeuk Kim
Samsung

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