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Date:   Fri, 4 Dec 2020 11:07:49 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, chao@kernel.org
Subject: Re: [PATCH v7] f2fs: compress: support compress level
Message-ID: <X8qJBdQZmZ2SyN9m@google.com>
References: <20201204102423.114091-1-yuchao0@huawei.com>
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On 12/04, Chao Yu wrote:
> Expand 'compress_algorithm' mount option to accept parameter as format of
> <algorithm>:<level>, by this way, it gives a way to allow user to do more
> specified config on lz4 and zstd compression level, then f2fs compression
> can provide higher compress ratio.
> 
> In order to set compress level for lz4 algorithm, it needs to set
> CONFIG_LZ4HC_COMPRESS and CONFIG_F2FS_FS_LZ4HC config to enable lz4hc
> compress algorithm.
> 
> CR and performance number on lz4/lz4hc algorithm:
> 
> dd if=enwik9 of=compressed_file conv=fsync
> 
> Original blocks:	244382
> 
> 			lz4			lz4hc-9
> compressed blocks	170647			163270
> compress ratio		69.8%			66.8%
> speed			16.4207 s, 60.9 MB/s	26.7299 s, 37.4 MB/s
> 
> compress ratio = after / before
> 
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> v7:
> - add test numbers for lz4/lz4hc
> - fix wrong compress level print
> - add compatibility description for LZ4HC in Kconfig
>  Documentation/filesystems/f2fs.rst |  5 +++
>  fs/f2fs/Kconfig                    | 10 +++++
>  fs/f2fs/compress.c                 | 40 ++++++++++++++++--
>  fs/f2fs/f2fs.h                     |  9 ++++
>  fs/f2fs/super.c                    | 67 +++++++++++++++++++++++++++++-
>  include/linux/f2fs_fs.h            |  3 ++
>  6 files changed, 129 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> index dae15c96e659..6ed2a787c947 100644
> --- a/Documentation/filesystems/f2fs.rst
> +++ b/Documentation/filesystems/f2fs.rst
> @@ -249,6 +249,11 @@ checkpoint=%s[:%u[%]]	 Set to "disable" to turn off checkpointing. Set to "enabl
>  			 This space is reclaimed once checkpoint=enable.
>  compress_algorithm=%s	 Control compress algorithm, currently f2fs supports "lzo",
>  			 "lz4", "zstd" and "lzo-rle" algorithm.
> +compress_algorithm=%s:%d Control compress algorithm and its compress level, now, only
> +			 "lz4" and "zstd" support compress level config.
> +			 		level range

I removed wrong spaces here and merged in dev-test till getting reviewed.

> +			 lz4		3 - 16
> +			 zstd		1 - 22
>  compress_log_size=%u	 Support configuring compress cluster size, the size will
>  			 be 4KB * (1 << %u), 16KB is minimum size, also it's
>  			 default size.
> diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig
> index d13c5c6a9787..63c1fc1a0e3b 100644
> --- a/fs/f2fs/Kconfig
> +++ b/fs/f2fs/Kconfig
> @@ -119,6 +119,16 @@ config F2FS_FS_LZ4
>  	help
>  	  Support LZ4 compress algorithm, if unsure, say Y.
>  
> +config F2FS_FS_LZ4HC
> +	bool "LZ4HC compression support"
> +	depends on F2FS_FS_COMPRESSION
> +	depends on F2FS_FS_LZ4
> +	select LZ4HC_COMPRESS
> +	default y
> +	help
> +	  Support LZ4HC compress algorithm, LZ4HC has compatible on-disk
> +	  layout with LZ4, if unsure, say Y.
> +
>  config F2FS_FS_ZSTD
>  	bool "ZSTD compression support"
>  	depends on F2FS_FS_COMPRESSION
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 247f4705e897..5bf37feea5a6 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -252,8 +252,13 @@ static const struct f2fs_compress_ops f2fs_lzo_ops = {
>  #ifdef CONFIG_F2FS_FS_LZ4
>  static int lz4_init_compress_ctx(struct compress_ctx *cc)
>  {
> -	cc->private = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
> -				LZ4_MEM_COMPRESS, GFP_NOFS);
> +	unsigned int size;
> +	unsigned char level = F2FS_I(cc->inode)->i_compress_flag >>
> +						COMPRESS_LEVEL_OFFSET;
> +
> +	size = level ? LZ4HC_MEM_COMPRESS : LZ4_MEM_COMPRESS;
> +
> +	cc->private = f2fs_kvmalloc(F2FS_I_SB(cc->inode), size, GFP_NOFS);
>  	if (!cc->private)
>  		return -ENOMEM;
>  
> @@ -272,10 +277,34 @@ static void lz4_destroy_compress_ctx(struct compress_ctx *cc)
>  	cc->private = NULL;
>  }
>  
> +#ifdef CONFIG_F2FS_FS_LZ4HC
> +static int lz4hc_compress_pages(struct compress_ctx *cc)
> +{
> +	unsigned char level = F2FS_I(cc->inode)->i_compress_flag >>
> +						COMPRESS_LEVEL_OFFSET;
> +	int len;
> +
> +	if (level)
> +		len = LZ4_compress_HC(cc->rbuf, cc->cbuf->cdata, cc->rlen,
> +					cc->clen, level, cc->private);
> +	else
> +		len = LZ4_compress_default(cc->rbuf, cc->cbuf->cdata, cc->rlen,
> +						cc->clen, cc->private);
> +	if (!len)
> +		return -EAGAIN;
> +
> +	cc->clen = len;
> +	return 0;
> +}
> +#endif
> +
>  static int lz4_compress_pages(struct compress_ctx *cc)
>  {
>  	int len;
>  
> +#ifdef CONFIG_F2FS_FS_LZ4HC
> +	return lz4hc_compress_pages(cc);
> +#endif
>  	len = LZ4_compress_default(cc->rbuf, cc->cbuf->cdata, cc->rlen,
>  						cc->clen, cc->private);
>  	if (!len)
> @@ -325,8 +354,13 @@ static int zstd_init_compress_ctx(struct compress_ctx *cc)
>  	ZSTD_CStream *stream;
>  	void *workspace;
>  	unsigned int workspace_size;
> +	unsigned char level = F2FS_I(cc->inode)->i_compress_flag >>
> +						COMPRESS_LEVEL_OFFSET;
> +
> +	if (!level)
> +		level = F2FS_ZSTD_DEFAULT_CLEVEL;
>  
> -	params = ZSTD_getParams(F2FS_ZSTD_DEFAULT_CLEVEL, cc->rlen, 0);
> +	params = ZSTD_getParams(level, cc->rlen, 0);
>  	workspace_size = ZSTD_CStreamWorkspaceBound(params.cParams);
>  
>  	workspace = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 7364d453783f..d6a83539153c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -146,6 +146,7 @@ struct f2fs_mount_info {
>  	/* For compression */
>  	unsigned char compress_algorithm;	/* algorithm type */
>  	unsigned char compress_log_size;	/* cluster log size */
> +	unsigned char compress_level;		/* compress level */
>  	bool compress_chksum;			/* compressed data chksum */
>  	unsigned char compress_ext_cnt;		/* extension count */
>  	int compress_mode;			/* compression mode */
> @@ -735,6 +736,7 @@ struct f2fs_inode_info {
>  	atomic_t i_compr_blocks;		/* # of compressed blocks */
>  	unsigned char i_compress_algorithm;	/* algorithm type */
>  	unsigned char i_log_cluster_size;	/* log of cluster size */
> +	unsigned char i_compress_level;		/* compress level (lz4hc,zstd) */
>  	unsigned short i_compress_flag;		/* compress flag */
>  	unsigned int i_cluster_size;		/* cluster size */
>  };
> @@ -1310,6 +1312,8 @@ struct compress_data {
>  
>  #define F2FS_COMPRESSED_PAGE_MAGIC	0xF5F2C000
>  
> +#define	COMPRESS_LEVEL_OFFSET	8
> +
>  /* compress context */
>  struct compress_ctx {
>  	struct inode *inode;		/* inode the context belong to */
> @@ -3932,6 +3936,11 @@ static inline void set_compress_context(struct inode *inode)
>  				1 << COMPRESS_CHKSUM : 0;
>  	F2FS_I(inode)->i_cluster_size =
>  			1 << F2FS_I(inode)->i_log_cluster_size;
> +	if (F2FS_I(inode)->i_compress_algorithm == COMPRESS_LZ4 &&
> +			F2FS_OPTION(sbi).compress_level)
> +		F2FS_I(inode)->i_compress_flag |=
> +				F2FS_OPTION(sbi).compress_level <<
> +				COMPRESS_LEVEL_OFFSET;
>  	F2FS_I(inode)->i_flags |= F2FS_COMPR_FL;
>  	set_inode_flag(inode, FI_COMPRESSED_FILE);
>  	stat_inc_compr_inode(inode);
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index c6a3365f4844..d16c84cc148d 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -25,6 +25,8 @@
>  #include <linux/quota.h>
>  #include <linux/unicode.h>
>  #include <linux/part_stat.h>
> +#include <linux/zstd.h>
> +#include <linux/lz4.h>
>  
>  #include "f2fs.h"
>  #include "node.h"
> @@ -464,6 +466,52 @@ static int f2fs_set_test_dummy_encryption(struct super_block *sb,
>  	return 0;
>  }
>  
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +static int f2fs_compress_set_level(struct f2fs_sb_info *sbi, const char *str,
> +						int type)
> +{
> +	unsigned int level;
> +	int len;
> +
> +	if (type == COMPRESS_LZ4)
> +		len = 3;
> +	else if (type == COMPRESS_ZSTD)
> +		len = 4;
> +	else
> +		return 0;
> +
> +	if (strlen(str) == len)
> +		return 0;
> +
> +	str += len;
> +
> +	if (str[0] != ':') {
> +		f2fs_info(sbi, "wrong format, e.g. <alg_name>:<compr_level>");
> +		return -EINVAL;
> +	}
> +	if (kstrtouint(str + 1, 10, &level))
> +		return -EINVAL;
> +	if (type == COMPRESS_LZ4) {
> +#ifdef CONFIG_F2FS_FS_LZ4HC
> +		if (level < LZ4HC_MIN_CLEVEL || level > LZ4HC_MAX_CLEVEL) {
> +			f2fs_info(sbi, "invalid lz4hc compress level: %d", level);
> +			return -EINVAL;
> +		}
> +#else
> +		f2fs_info(sbi, "doesn't support lz4hc compression");
> +		return 0;
> +#endif
> +	} else if (type == COMPRESS_ZSTD) {
> +		if (!level || level > ZSTD_maxCLevel()) {
> +			f2fs_info(sbi, "invalid zstd compress level: %d", level);
> +			return -EINVAL;
> +		}
> +	}
> +	F2FS_OPTION(sbi).compress_level = level;
> +	return 0;
> +}
> +#endif
> +
>  static int parse_options(struct super_block *sb, char *options, bool is_remount)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_SB(sb);
> @@ -884,10 +932,22 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
>  			if (!strcmp(name, "lzo")) {
>  				F2FS_OPTION(sbi).compress_algorithm =
>  								COMPRESS_LZO;
> -			} else if (!strcmp(name, "lz4")) {
> +			} else if (!strncmp(name, "lz4", 3)) {
> +				ret = f2fs_compress_set_level(sbi, name,
> +								COMPRESS_LZ4);
> +				if (ret) {
> +					kfree(name);
> +					return -EINVAL;
> +				}
>  				F2FS_OPTION(sbi).compress_algorithm =
>  								COMPRESS_LZ4;
> -			} else if (!strcmp(name, "zstd")) {
> +			} else if (!strncmp(name, "zstd", 4)) {
> +				ret = f2fs_compress_set_level(sbi, name,
> +								COMPRESS_ZSTD);
> +				if (ret) {
> +					kfree(name);
> +					return -EINVAL;
> +				}
>  				F2FS_OPTION(sbi).compress_algorithm =
>  								COMPRESS_ZSTD;
>  			} else if (!strcmp(name, "lzo-rle")) {
> @@ -1539,6 +1599,9 @@ static inline void f2fs_show_compress_options(struct seq_file *seq,
>  	}
>  	seq_printf(seq, ",compress_algorithm=%s", algtype);
>  
> +	if (F2FS_OPTION(sbi).compress_level)
> +		seq_printf(seq, ":%d", F2FS_OPTION(sbi).compress_level);
> +
>  	seq_printf(seq, ",compress_log_size=%u",
>  			F2FS_OPTION(sbi).compress_log_size);
>  
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index 7dc2a06cf19a..c6cc0a566ef5 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -274,6 +274,9 @@ struct f2fs_inode {
>  			__u8 i_compress_algorithm;	/* compress algorithm */
>  			__u8 i_log_cluster_size;	/* log of cluster size */
>  			__le16 i_compress_flag;		/* compress flag */
> +						/* 0 bit: chksum flag
> +						 * [10,15] bits: compress level
> +						 */
>  			__le32 i_extra_end[0];	/* for attribute size calculation */
>  		} __packed;
>  		__le32 i_addr[DEF_ADDRS_PER_INODE];	/* Pointers to data blocks */
> -- 
> 2.29.2