linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: set zstd default compression level to 3

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Message-ID: <85ff67e0-c6c6-e693-bcba-6e36a3dd2ea4@kernel.org>
Date:   Mon, 12 Jun 2023 22:23:52 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: set zstd default compression level to 3

On 2023/6/8 0:29, Jaegeuk Kim wrote:
> ZSTD does not support compress_level=0.

IIUC, it looks the range is [0, ZSTD_MAX_CLEVEL], 0 equals to default
(ZSTD_CLEVEL_DEFAULT).

zstd_compress.c

     /* row */
     if (compressionLevel == 0) row = ZSTD_CLEVEL_DEFAULT;   /* 0 == default */
     else if (compressionLevel < 0) row = 0;   /* entry 0 is baseline for fast mode */
     else if (compressionLevel > ZSTD_MAX_CLEVEL) row = ZSTD_MAX_CLEVEL;
     else row = compressionLevel;

Thanks,

> 
> The commit d7ffafc99c42 ("f2fs: add sanity compress level check for compressed file")
> revealed the issue.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>   fs/f2fs/super.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 8fd23caa1ed9..1fb8d4f27a40 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -627,7 +627,7 @@ static int f2fs_set_zstd_level(struct f2fs_sb_info *sbi, const char *str)
>   	int len = 4;
>   
>   	if (strlen(str) == len) {
> -		F2FS_OPTION(sbi).compress_level = 0;
> +		F2FS_OPTION(sbi).compress_level = 3;
>   		return 0;
>   	}
>