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Date:   Wed, 18 Jan 2023 18:29:57 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Yangtao Li <frank.li@vivo.com>
Cc:     chao@kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] f2fs: export compress_percent and compress_watermark
 entries
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References: <20230117131740.76597-1-frank.li@vivo.com>
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On 01/17, Yangtao Li wrote:
> This patch export below sysfs entries for better control cached
> compress page count.
> 
> /sys/fs/f2fs/<disk>/compress_watermark
> /sys/fs/f2fs/<disk>/compress_percent
> 
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
>  Documentation/ABI/testing/sysfs-fs-f2fs | 17 +++++++++++++++++
>  fs/f2fs/sysfs.c                         | 18 ++++++++++++++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 75420c242cc4..920562742655 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -717,3 +717,20 @@ Description:	Controls background discard granularity of inner discard thread
>  		is smaller than granularity. The unit size is one block(4KB), now only
>  		support configuring in range of [0, 512].
>  		Default: 512
> +
> +what:		/sys/fs/f2fs/<disk>/compress_watermark
> +date:		january 2023
> +contact:	"yangtao li" <frank.li@vivo.com>
> +description:	when compress_cache is on, it controls free memory watermark
> +		in order to limit caching compress page. If free memory is lower
> +		than watermark, then deny caching compress page. The value should be in
> +		range of [0, 100], by default it was initialized as 20(%).
> +
> +what:		/sys/fs/f2fs/<disk>/compress_percent
> +date:		january 2023
> +contact:	"yangtao li" <frank.li@vivo.com>
> +description:	when compress_cache is on, it controls cached page
> +		percent(compress pages / free_ram) in order to limit caching compress page.
> +		If cached page percent exceed threshold, then deny caching compress page.
> +		The value should be in range of [0, 100], by default it was initialized
> +		as 20(%).
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index e396851a6dd1..37c6ef080f7e 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -598,6 +598,20 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>  		sbi->compr_new_inode = 0;
>  		return count;
>  	}
> +
> +	if (!strcmp(a->attr.name, "compress_percent")) {
> +		if (t > 100)

t=0 also doesn't make sense.

> +			return -EINVAL;
> +		*ui = t;
> +		return count;
> +	}
> +
> +	if (!strcmp(a->attr.name, "compress_watermark")) {
> +		if (t > 100)
> +			return -EINVAL;
> +		*ui = t;
> +		return count;
> +	}
>  #endif
>  
>  	if (!strcmp(a->attr.name, "atgc_candidate_ratio")) {
> @@ -932,6 +946,8 @@ F2FS_FEATURE_RO_ATTR(compression);
>  F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_written_block, compr_written_block);
>  F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_saved_block, compr_saved_block);
>  F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_new_inode, compr_new_inode);
> +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compress_percent, compress_percent);
> +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compress_watermark, compress_watermark);
>  #endif
>  F2FS_FEATURE_RO_ATTR(pin_file);
>  
> @@ -1038,6 +1054,8 @@ static struct attribute *f2fs_attrs[] = {
>  	ATTR_LIST(compr_written_block),
>  	ATTR_LIST(compr_saved_block),
>  	ATTR_LIST(compr_new_inode),
> +	ATTR_LIST(compress_percent),
> +	ATTR_LIST(compress_watermark),
>  #endif
>  	/* For ATGC */
>  	ATTR_LIST(atgc_candidate_ratio),
> -- 
> 2.25.1