linux-kernel - Re: [PATCH v2] f2fs: free_user_blocks should use reserved

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Date:   Fri, 18 Aug 2017 18:02:13 +0800
From:   Yunlong Song <yunlong.song@...wei.com>
To:     <jaegeuk@...nel.org>, <chao@...nel.org>, <yuchao0@...wei.com>,
        <yunlong.song@...oud.com>
CC:     <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] f2fs: free_user_blocks should use reserved_segments
 instead

ping...

On 2017/8/15 15:14, Yunlong Song wrote:
> The part (overprovision_segments - reserved_segments) can still be used for LFS
> in some case, e.g., there are lots of invalid block from dirty segments, then
> the part (overprovision_segments - reserved_segments) can be safely used. So
> free_use_blocks should use reserved_segments instead, rather than directly use
> overprovision_segments. BTW, we also add the constraint of sbi->reserved_blocks.
>
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
> ---
>   fs/f2fs/gc.h | 18 +++++++++++++++---
>   1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
> index 9325191..542612a 100644
> --- a/fs/f2fs/gc.h
> +++ b/fs/f2fs/gc.h
> @@ -49,11 +49,23 @@ struct gc_inode_list {
>    */
>   static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
>   {
> -	if (free_segments(sbi) < overprovision_segments(sbi))
> +	block_t avail_user_block_count, free_blocks, avail_free_blocks;
> +	block_t reserved_blocks;
> +
> +	avail_user_block_count = sbi->user_block_count - sbi->reserved_blocks;
> +
> +	if (unlikely(sbi->total_valid_block_count > avail_user_block_count))
> +		return 0;
> +
> +	free_blocks = free_segments(sbi) << sbi->log_blocks_per_seg;
> +	avail_free_blocks = min(free_blocks, avail_user_block_count -
> +								sbi->total_valid_block_count);
> +	reserved_blocks = reserved_segments(sbi) << sbi->log_blocks_per_seg;
> +
> +	if (avail_free_blocks < reserved_blocks)
>   		return 0;
>   	else
> -		return (free_segments(sbi) - overprovision_segments(sbi))
> -			<< sbi->log_blocks_per_seg;
> +		return avail_free_blocks - reserved_blocks;
>   }
>   
>   static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)

-- 
Thanks,
Yunlong Song