linux-kernel - Re: [PATCH] f2fs: set file as cold when file defragmentation

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Date:   Thu, 6 May 2021 10:09:18 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <daejun7.park@...sung.com>,
        "jaegeuk@...nel.org" <jaegeuk@...nel.org>,
        "chao@...nel.org" <chao@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-f2fs-devel@...ts.sourceforge.net" 
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [PATCH] f2fs: set file as cold when file defragmentation

On 2021/4/29 14:20, Daejun Park wrote:
> In file defragmentation by ioctl, all data blocks in the file are
> re-written out-of-place. File defragmentation implies user will not update
> and mostly read the file. So before the defragmentation, we set file
> temperature as cold for better block allocation.

I don't think all fragmented files are cold, e.g. db file.

We have separated interface (via f2fs_xattr_advise_handler, e.g. setfattr -n
"system.advise" -v value) to indicate this file is a hot/cold file, so my
suggestion is after file defragmentation, if you think this file is cold, and
use setxattr() to set it as cold.

Thanks,

> 
> Signed-off-by: Daejun Park <daejun7.park@...sung.com>
> ---
>   fs/f2fs/file.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index d697c8900fa7..dcac965a05fe 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2669,6 +2669,9 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
>   	map.m_len = pg_end - pg_start;
>   	total = 0;
>   
> +	if (!file_is_cold(inode))
> +		file_set_cold(inode);
> +
>   	while (map.m_lblk < pg_end) {
>   		pgoff_t idx;
>   		int cnt = 0;
>