linux-kernel - Re: [PATCH] f2fs: fix not to allocate max

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Message-ID: <CAKYAXd92_Lxp9A3QCzwhWdctMz=AMVUwzOEqxcbRppLH5dn+hQ@mail.gmail.com>
Date:	Mon, 18 Mar 2013 18:29:03 +0900
From:	Namjae Jeon <linkinjeon@...il.com>
To:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH] f2fs: fix not to allocate max_nid

2013/3/18, Jaegeuk Kim <jaegeuk.kim@...sung.com>:
> The build_free_nid should not add free nids over nm_i->max_nid.
> But, there was a hole that invalid free nid was added by the following
> scenario.
>
> Let's suppose nm_i->max_nid = 150 and the last NAT page has 100 ~ 200 nids.
>
> build_free_nids
>   - get_current_nat_page loads the last NAT page
>   - scan_nat_page can add 100 ~ 200 nids
>     -> Bug here!
> So, when scanning an NAT page, we should check each candidate whether it is
> over max_nid or not.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
> ---
>  fs/f2fs/node.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index c60919f..3fb6dfe 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1270,6 +1270,8 @@ static int scan_nat_page(struct f2fs_nm_info *nm_i,
>  	i = start_nid % NAT_ENTRY_PER_BLOCK;
>
>  	for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {
> +		if (start_nid >= nm_i->max_nid)
> +			return fcnt;
Hi Jaegeuk.
How about use "break;" instread of "return fcnt" ?
I think that break is better because there is no extra condition before return.

Thanks.
>  		blk_addr  = le32_to_cpu(nat_blk->entries[i].block_addr);
>  		BUG_ON(blk_addr == NEW_ADDR);
>  		if (blk_addr == NULL_ADDR)
> --
> 1.8.1.3.566.gaa39828
>
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