linux-kernel - Re: [f2fs-dev] [PATCH RESEND v2] f2fs: validate before set/clear free nat bitmap

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Date:   Mon, 20 Nov 2017 10:58:35 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     LiFan <fanofcode.li@...sung.com>, "'Chao Yu'" <chao@...nel.org>,
        "'Jaegeuk Kim'" <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH RESEND v2] f2fs: validate before set/clear free
 nat bitmap

On 2017/11/14 15:20, LiFan wrote:
> In flush_nat_entries, all dirty nats will be flushed and if their new address
> isn't NULL_ADDR, their bitmaps will be updated, the free_nid_count of the
> bitmaps will be increased regardless of whether the nats have already been
> occupied before. This could lead to wrong free_nid_count.
> So this patch checks the status of the bits before actually set/clear them.
> 
> Fixes: 586d1492f301 ("f2fs: skip scanning free nid bitmap of full NAT blocks")
> 
> Signed-off-by: Fan li <fanofcode.li@...sung.com>

Reviewed-by: Chao Yu <yuchao0@...wei.com>

Thanks,

> ---
>  fs/f2fs/node.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index d234c6e..b965a53 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1906,15 +1906,18 @@ static void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid,
>  	if (!test_bit_le(nat_ofs, nm_i->nat_block_bitmap))
>  		return;
>  
> -	if (set)
> +	if (set) {
> +		if (test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))
> +			return;
>  		__set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
> -	else
> -		__clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
> -
> -	if (set)
>  		nm_i->free_nid_count[nat_ofs]++;
> -	else if (!build)
> -		nm_i->free_nid_count[nat_ofs]--;
> +	} else {
> +		if (!test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))
> +			return;
> +		__clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
> +		if (!build)
> +			nm_i->free_nid_count[nat_ofs]--;
> +	}
>  }
>  
>  static void scan_nat_page(struct f2fs_sb_info *sbi,
> --
> 2.7.4
> 
> 
> 
>