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Message-id: <1397719003.7727.24.camel@kjgkr>
Subject: Re: [f2fs-dev] [PATCH] f2fs: fix wrong number of max_nid when init
From: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Reply-to: jaegeuk.kim@samsung.com
To: Chao Yu <chao2.yu@samsung.com>
Cc: linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date: Thu, 17 Apr 2014 16:16:43 +0900
In-reply-to: <000c01cf5a06$46b1ba30$d4152e90$@samsung.com>
References: <000c01cf5a06$46b1ba30$d4152e90$@samsung.com>
Organization: Samsung
DLP-Filter: Pass
Sender: linux-kernel-owner@vger.kernel.org

Hi,

2014-04-17 (목), 14:27 +0800, Chao Yu:
> Since max_nid value was minus three in previous commit:
> 'b63da15e8b475245026bdf2096853683f189706b', Our last three nids could not be
> used ever, but 0/node nid/meta nid is still occupied.
> And also our ra_meta_pages() could not readahead the last block of NAT.

What is the root problem in there?
IIRC, the max_nid should not be turned back since that can cause an
infinite loop during build_free_nids() under a test using whole the
nids.

> Let's fix the wrong calculation of this value, and left the reserved nids there.
> 
> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> ---
>  fs/f2fs/node.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 84f9b7b..3f0bb50 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1860,7 +1860,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
>  	nat_blocks = nat_segs << le32_to_cpu(sb_raw->log_blocks_per_seg);
>  
>  	/* not used nids: 0, node, meta, (and root counted as valid node) */
> -	nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks - 3;
> +	nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks;
>  	nm_i->fcnt = 0;
>  	nm_i->nat_cnt = 0;
>  	nm_i->ram_thresh = DEF_RAM_THRESHOLD;

-- 
Jaegeuk Kim
Samsung

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