linux-kernel - Re: [PATCH 9/9] f2fs: fix the bitmap consistency of dirty segments

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Date:	Wed, 3 Apr 2013 10:14:40 +0900
From:	Namjae Jeon <linkinjeon@...il.com>
To:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH 9/9] f2fs: fix the bitmap consistency of dirty segments

2013/4/1, Jaegeuk Kim <jaegeuk.kim@...sung.com>:
> Like below, there are 8 segment bitmaps for SSR victim candidates.
>
> enum dirty_type {
> 	DIRTY_HOT_DATA,		/* dirty segments assigned as hot data logs */
> 	DIRTY_WARM_DATA,	/* dirty segments assigned as warm data logs */
> 	DIRTY_COLD_DATA,	/* dirty segments assigned as cold data logs */
> 	DIRTY_HOT_NODE,		/* dirty segments assigned as hot node logs */
> 	DIRTY_WARM_NODE,	/* dirty segments assigned as warm node logs */
> 	DIRTY_COLD_NODE,	/* dirty segments assigned as cold node logs */
> 	DIRTY,			/* to count # of dirty segments */
> 	PRE,			/* to count # of entirely obsolete segments */
> 	NR_DIRTY_TYPE
> };
>
> The upper 6 bitmaps indicates segments dirtied by active log areas
> respectively.
> And, the DIRTY bitmap integrates all the 6 bitmaps.
>
> For example,
>  o DIRTY_HOT_DATA : 1010000
>  o DIRTY_WARM_DATA: 0100000
>  o DIRTY_COLD_DATA: 0001000
>  o DIRTY_HOT_NODE : 0000010
>  o DIRTY_WARM_NODE: 0000001
>  o DIRTY_COLD_NODE: 0000000
> In this case,
>  o DIRTY          : 1111011,
>
>  which means that we should guarantee the consistency between DIRTY and
> other
>  bitmaps concreately.
>
> However, the SSR mode selects victims freely from any log types, which can
> set
> multiple bits across the various bitmap types.
>
> So, this patch eliminates this inconsistency.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
Looks good to me~
Reviewed-by: Namjae Jeon <namjae.jeon@...sung.com>

Thanks.
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