RE: [f2fs-dev] [PATCH 2/2] f2fs: fix to overcome inline_data floods

[Chao Yu <chao2.yu@samsung.com>]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@kernel.org]
> Sent: Sunday, January 24, 2016 4:16 AM
> To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 2/2] f2fs: fix to overcome inline_data floods
> 
> The scenario is:
> 1. create lots of node blocks
> 2. sync
> 3. write lots of inline_data
> -> got panic due to no free space
> 
> In that case, we should flush node blocks when writing inline_data in #3,
> and trigger gc as well.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  fs/f2fs/gc.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 0204433..8686231 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -838,8 +838,15 @@ gc_more:
> 
>  	if (gc_type == BG_GC && has_not_enough_free_secs(sbi, sec_freed)) {
>  		gc_type = FG_GC;
> +		/*
> +		 * If there is no victim and no prefree segment but still not
> +		 * enough free sections, we should flush dent/node blocks and do
> +		 * garbage collections.
> +		 */
>  		if (__get_victim(sbi, &segno, gc_type) || prefree_segments(sbi))
>  			write_checkpoint(sbi, &cpc);
> +		else if (has_not_enough_free_secs(sbi, 0))

I think this condition make checkpoint been triggered more frequently,
could we trigger cp when dent/node block exceed some threshold?

Thanks,

> +			write_checkpoint(sbi, &cpc);
>  	}
> 
>  	if (segno == NULL_SEGNO && !__get_victim(sbi, &segno, gc_type))
> --
> 2.6.3
> 
> 
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