Re: [f2fs-dev] [PATCH 1/5] f2fs: relax node version check for victim data in gc

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From	Chao Yu <yuchao0@huawei.com>
Newsgroups	linux.kernel
Subject	Re: [f2fs-dev] [PATCH 1/5] f2fs: relax node version check for victim data in gc
Date	Sat, 25 Mar 2017 10:10:01 +0100
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Hi Jaegeuk,

On 2017/3/25 15:59, Jaegeuk Kim wrote:
> - has_not_enough_free_secs
> node_secs: 0  dent_secs: 0  freed:0  free_segments:103  reserved:104
> 
>           - f2fs_gc
>              - get_victim_by_default
> alloc_mode 0, gc_mode 1, max_search 2672, offset 4654, ofs_unit 1
> 
>                 - do_garbage_collect
> start_segno 3976, end_segno 3977   type 0
> 
>                   - is_alive
> nid 22797, blkaddr 2131882, ofs_in_node 0, version 0x8/0x0
> 
>                    - gc_data_segment 766, segno 3976, block 512/426 not alive
> 
> So, this patch fixes subtle corrupted case where node version does not match
> to summary version which results in infinite loop by gc.
> 
> Reported-by: Yunlei He <heyunlei@huawei.com>
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  fs/f2fs/gc.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 939be88a8833..bbeee41aaf73 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -551,8 +551,10 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>  	get_node_info(sbi, nid, dni);
>  
>  	if (sum->version != dni->version) {

If the node was been truncated, we will increase its version number, since it
was been truncated, so it will never be writebacked to storage, so the version
in summary will not be updated.

So this case can happen, shouldn't we just set SBI_NEED_FSCK for the case:
sum->version != dni->version - 1

Thanks,

> -		f2fs_put_page(node_page, 1);
> -		return false;
> +		f2fs_msg(sbi->sb, KERN_WARNING,
> +				"%s: valid data with mismatched node version.",
> +				__func__);
> +		set_sbi_flag(sbi, SBI_NEED_FSCK);
>  	}
>  
>  	*nofs = ofs_of_node(node_page);
>

Thread

[PATCH 1/5] f2fs: relax node version check for victim data in gc Jaegeuk Kim <jaegeuk@kernel.org> - 2017-03-25 09:00 +0100
  [PATCH 3/5] f2fs: allocate node and hot data in the beginning of partition Jaegeuk Kim <jaegeuk@kernel.org> - 2017-03-25 09:10 +0100
  [PATCH 5/5] f2fs: fix wrong max cost initialization Jaegeuk Kim <jaegeuk@kernel.org> - 2017-03-25 09:10 +0100
  [PATCH 4/5] f2fs: start SSR much eariler to avoid FG_GC Jaegeuk Kim <jaegeuk@kernel.org> - 2017-03-25 09:10 +0100
  [PATCH 2/5] f2fs: write small sized IO to hot log Jaegeuk Kim <jaegeuk@kernel.org> - 2017-03-25 09:10 +0100
  Re: [f2fs-dev] [PATCH 1/5] f2fs: relax node version check for victim  data in gc Chao Yu <yuchao0@huawei.com> - 2017-03-25 10:10 +0100
    Re: [f2fs-dev] [PATCH 1/5] f2fs: relax node version check for victim  data in gc Jaegeuk Kim <jaegeuk@kernel.org> - 2017-03-25 22:30 +0100
      Re: [f2fs-dev] [PATCH 1/5] f2fs: relax node version check for victim  data in gc Chao Yu <yuchao0@huawei.com> - 2017-03-27 10:20 +0200

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