linux-kernel - Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid to select pinned section during checkpoint=disable

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Date:   Wed, 4 May 2022 23:01:08 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid to select pinned section
 during checkpoint=disable

On 2022/5/4 4:30, Jaegeuk Kim wrote:
> The f2fs_gc uses a bitmap to indicate pinned sections, but when disabling
> chckpoint, we call f2fs_gc() with NULL_SEGNO which selects the same dirty
> segment as a victim all the time, resulting in checkpoint=disable failure.
> Let's pick another one, if we fail to collect it.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>   fs/f2fs/gc.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 4d47723523c3..5ba8104e138b 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1838,10 +1838,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>   	if (gc_type == FG_GC)
>   		sbi->cur_victim_sec = NULL_SEGNO;
>   
> -	if (sync)
> -		goto stop;

Semantics of 'sync' parameter should be: migrate one section at least before
exit?

So, should it be?

if (seg_freed && (sync || !has_not_enough_free_secs(sbi, sec_freed, 0)))
	goto stop;

Thanks,

> -
> -	if (!has_not_enough_free_secs(sbi, sec_freed, 0))
> +	if (!has_not_enough_free_secs(sbi, sec_freed, 0) && seg_freed)
>   		goto stop;
>   
>   	if (skipped_round <= MAX_SKIP_GC_COUNT || skipped_round * 2 < round) {