linux-kernel - Re: [PATCH 4/5] f2fs: disable small discard in lfs mode

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Date:   Fri, 13 Jul 2018 11:17:48 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Yunlong Song <yunlong.song@...wei.com>, <jaegeuk@...nel.org>,
        <chao@...nel.org>, <yunlong.song@...oud.com>
CC:     <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
        <shengyong1@...wei.com>, <heyunlei@...wei.com>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5] f2fs: disable small discard in lfs mode

On 2018/7/12 23:09, Yunlong Song wrote:
> In lfs mode, it is better to send the discard of the overall section
> each time to avoid missing alignment with flash.

Hmm.. I think LFS mode can be used widely on different kind of device instead of
just on zoned block device, so let's just keep old implementation here.

Thanks,

> 
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
> ---
>  fs/f2fs/segment.c | 3 ++-
>  fs/f2fs/sysfs.c   | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index fd38b61..f6c20e0 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1766,7 +1766,8 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
>  	atomic_set(&dcc->issing_discard, 0);
>  	atomic_set(&dcc->discard_cmd_cnt, 0);
>  	dcc->nr_discards = 0;
> -	dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
> +	dcc->max_discards = test_opt(sbi, LFS) ? 0 :
> +				MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
>  	dcc->undiscard_blks = 0;
>  	dcc->root = RB_ROOT;
>  	dcc->rbtree_check = false;
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 2e7e611..4b6c457 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -271,6 +271,10 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>  		return count;
>  	}
>  
> +	if (!strcmp(a->attr.name, "max_small_discards") &&
> +		test_opt(sbi, LFS))
> +		return -EINVAL;
> +
>  	*ui = t;
>  
>  	if (!strcmp(a->attr.name, "iostat_enable") && *ui == 0)
>