linux-kernel - Re: [f2fs-dev] [PATCH 1/2] f2fs: do not select same victim right again

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Date:   Mon, 9 Sep 2019 19:32:07 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: do not select same victim right
 again

On 2019/9/9 16:06, Jaegeuk Kim wrote:
> On 09/09, Chao Yu wrote:
>> On 2019/9/9 9:25, Jaegeuk Kim wrote:
>>> GC must avoid select the same victim again.
>>
>> Blocks in previous victim will occupy addition free segment, I doubt after this
>> change, FGGC may encounter out-of-free space issue more frequently.
> 
> Hmm, actually this change seems wrong by sec_usage_check().
> We may be able to avoid this only in the suspicious loop?
> 
> ---
>  fs/f2fs/gc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index e88f98ddf396..5877bd729689 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1326,7 +1326,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>  		round++;
>  	}
>  
> -	if (gc_type == FG_GC)
> +	if (gc_type == FG_GC && seg_freed)

That's original solution Sahitya provided to avoid infinite loop of GC, but I
suggest to find the root cause first, then we added .invalid_segmap for that
purpose.

Thanks,

>  		sbi->cur_victim_sec = NULL_SEGNO;
>  
>  	if (sync)
>