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Date: Wed, 7 Feb 2024 16:07:35 -0800
From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
	Sheng Yong <shengyong@oppo.com>
Subject: Re: [PATCH] f2fs: support compress extension update via sysfs
 interface
Message-ID: <ZcQbRzyvb8MNeOMB@google.com>
References: <20240207062546.3083870-1-chao@kernel.org>
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On 02/07, Chao Yu wrote:
> Introduce /sys/fs/f2fs/<disk>/compress_extension to support
> adding/deleting compress extension via sysfs interface, in
> comparison to mount option, it's more easy to use and less
> authority issue for applications.
> 
> Usage:
> - Query: cat /sys/fs/f2fs/<disk>/compress_extension
> - Add: echo '[c|n]extension' > /sys/fs/f2fs/<disk>/compress_extension
> - Del: echo '[c|n]!extension' > /sys/fs/f2fs/<disk>/compress_extension
> - [c] means add/del compress extension
> - [n] means add/del nocompress extension
> 
> Signed-off-by: Sheng Yong <shengyong@oppo.com>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>  Documentation/ABI/testing/sysfs-fs-f2fs | 10 ++++
>  Documentation/filesystems/f2fs.rst      |  6 ++-
>  fs/f2fs/compress.c                      | 61 +++++++++++++++++++++++
>  fs/f2fs/f2fs.h                          |  4 +-
>  fs/f2fs/sysfs.c                         | 65 +++++++++++++++++++++++--
>  5 files changed, 139 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 48c135e24eb5..1f2cc0913e45 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -762,3 +762,13 @@ Date:		November 2023
>  Contact:	"Chao Yu" <chao@kernel.org>
>  Description:	It controls to enable/disable IO aware feature for background discard.
>  		By default, the value is 1 which indicates IO aware is on.
> +
> +What:		/sys/fs/f2fs/<disk>/compress_extension
> +Date:		October 2023
> +Contact:	"Chao Yu" <chao@kernel.org>
> +Description:	Used to control configure [|no]compress_extension list:
> +		- Query: cat /sys/fs/f2fs/<disk>/compress_extension
> +		- Add: echo '[c|n]extension' > /sys/fs/f2fs/<disk>/compress_extension
> +		- Del: echo '[c|n]!extension' > /sys/fs/f2fs/<disk>/compress_extension
> +		- [c] means add/del compress extension
> +		- [n] means add/del nocompress extension
> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> index 32cbfa864f38..c82a8fd7316b 100644
> --- a/Documentation/filesystems/f2fs.rst
> +++ b/Documentation/filesystems/f2fs.rst
> @@ -821,17 +821,19 @@ Compression implementation
>    all logical blocks in cluster contain valid data and compress ratio of
>    cluster data is lower than specified threshold.
>  
> -- To enable compression on regular inode, there are four ways:
> +- To enable compression on regular inode, there are five ways:
>  
>    * chattr +c file
>    * chattr +c dir; touch dir/file
>    * mount w/ -o compress_extension=ext; touch file.ext
>    * mount w/ -o compress_extension=*; touch any_file
> +  * echo '[c]ext' > /sys/fs/f2fs/<disk>/compress_extension; touch file.ext
>  
> -- To disable compression on regular inode, there are two ways:
> +- To disable compression on regular inode, there are three ways:
>  
>    * chattr -c file
>    * mount w/ -o nocompress_extension=ext; touch file.ext
> +  * echo '[n]ext' > /sys/fs/f2fs/<disk>/compress_extension; touch file.ext
>  
>  - Priority in between FS_COMPR_FL, FS_NOCOMP_FS, extensions:
>  
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 3dc488ce882b..a5257882c772 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -20,6 +20,67 @@
>  #include "segment.h"
>  #include <trace/events/f2fs.h>
>  
> +static int is_compress_extension_exist(struct f2fs_sb_info *sbi,
> +				unsigned char (*ext)[F2FS_EXTENSION_LEN],
> +				int ext_cnt, unsigned char *new_ext)
> +{
> +	int i;
> +
> +	for (i = 0; i < ext_cnt; i++) {
> +		if (!strcasecmp(new_ext, ext[i]))
> +			return i;
> +	}
> +	return -1;
> +}
> +
> +int f2fs_update_compress_extension(struct f2fs_sb_info *sbi,
> +				unsigned char *new_ext, bool is_ext, bool set)
> +{
> +	unsigned char (*ext)[F2FS_EXTENSION_LEN];
> +	unsigned char *ext_cnt;
> +
> +	if (is_ext) {
> +		ext = F2FS_OPTION(sbi).extensions;
> +		ext_cnt = &F2FS_OPTION(sbi).compress_ext_cnt;
> +	} else {
> +		ext = F2FS_OPTION(sbi).noextensions;
> +		ext_cnt = &F2FS_OPTION(sbi).nocompress_ext_cnt;
> +	}
> +
> +	if (set) {
> +		if (*ext_cnt >= COMPRESS_EXT_NUM)
> +			return -EINVAL;
> +
> +		if (is_compress_extension_exist(sbi,
> +					F2FS_OPTION(sbi).extensions,
> +					F2FS_OPTION(sbi).compress_ext_cnt,
> +					new_ext) >= 0)
> +			return -EEXIST;
> +
> +		if (is_compress_extension_exist(sbi,
> +					F2FS_OPTION(sbi).noextensions,
> +					F2FS_OPTION(sbi).nocompress_ext_cnt,
> +					new_ext) >= 0)
> +			return -EEXIST;
> +
> +		strcpy(ext[*ext_cnt], new_ext);
> +		(*ext_cnt)++;
> +	} else {
> +		int pos = is_compress_extension_exist(sbi, ext,
> +						*ext_cnt, new_ext);
> +		if (pos < 0)
> +			return -ENOENT;
> +
> +		if (pos < *ext_cnt - 1)
> +			memmove(ext + pos, ext + pos + 1,
> +				F2FS_EXTENSION_LEN * (*ext_cnt - pos - 1));
> +		memset(ext + *ext_cnt - 1, 0, F2FS_EXTENSION_LEN);
> +		(*ext_cnt)--;
> +	}
> +
> +	return 0;
> +}
> +
>  static struct kmem_cache *cic_entry_slab;
>  static struct kmem_cache *dic_entry_slab;
>  
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c5e7460d1a0a..d44e2c43d8ab 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -186,7 +186,7 @@ struct f2fs_mount_info {
>  	unsigned char compress_level;		/* compress level */
>  	bool compress_chksum;			/* compressed data chksum */
>  	unsigned char compress_ext_cnt;		/* extension count */
> -	unsigned char nocompress_ext_cnt;		/* nocompress extension count */
> +	unsigned char nocompress_ext_cnt;	/* nocompress extension count */
>  	int compress_mode;			/* compression mode */
>  	unsigned char extensions[COMPRESS_EXT_NUM][F2FS_EXTENSION_LEN];	/* extensions */
>  	unsigned char noextensions[COMPRESS_EXT_NUM][F2FS_EXTENSION_LEN]; /* extensions */
> @@ -4273,6 +4273,8 @@ static inline bool f2fs_post_read_required(struct inode *inode)
>   * compress.c
>   */
>  #ifdef CONFIG_F2FS_FS_COMPRESSION
> +int f2fs_update_compress_extension(struct f2fs_sb_info *sbi,
> +				unsigned char *new_ext, bool is_ext, bool set);
>  bool f2fs_is_compressed_page(struct page *page);
>  struct page *f2fs_compress_control_page(struct page *page);
>  int f2fs_prepare_compress_overwrite(struct inode *inode,
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index a7ec55c7bb20..a8f05a02e202 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -39,6 +39,7 @@ enum {
>  	RESERVED_BLOCKS,	/* struct f2fs_sb_info */
>  	CPRC_INFO,	/* struct ckpt_req_control */
>  	ATGC_INFO,	/* struct atgc_management */
> +	MOUNT_INFO,	/* struct f2fs_mount_info */
>  };
>  
>  static const char *gc_mode_names[MAX_GC_MODE] = {
> @@ -89,6 +90,8 @@ static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type)
>  		return (unsigned char *)&sbi->cprc_info;
>  	else if (struct_type == ATGC_INFO)
>  		return (unsigned char *)&sbi->am;
> +	else if (struct_type == MOUNT_INFO)
> +		return (unsigned char *)&F2FS_OPTION(sbi);
>  	return NULL;
>  }
>  
> @@ -358,6 +361,25 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
>  
>  	if (!strcmp(a->attr.name, "compr_new_inode"))
>  		return sysfs_emit(buf, "%u\n", sbi->compr_new_inode);
> +
> +	if (!strcmp(a->attr.name, "compress_extension")) {
> +		int len = 0, i;
> +
> +		f2fs_down_read(&sbi->sb_lock);
> +		len += scnprintf(buf + len, PAGE_SIZE - len,
> +						"compress extension:\n");
> +		for (i = 0; i < F2FS_OPTION(sbi).compress_ext_cnt; i++)
> +			len += scnprintf(buf + len, PAGE_SIZE - len, "%s\n",
> +					F2FS_OPTION(sbi).extensions[i]);
> +
> +		len += scnprintf(buf + len, PAGE_SIZE - len,
> +						"nocompress extension:\n");
> +		for (i = 0; i < F2FS_OPTION(sbi).nocompress_ext_cnt; i++)
> +			len += scnprintf(buf + len, PAGE_SIZE - len, "%s\n",
> +					F2FS_OPTION(sbi).noextensions[i]);

I don't think this is acceptable in sysfs.

> +		f2fs_up_read(&sbi->sb_lock);
> +		return len;
> +	}
>  #endif
>  
>  	if (!strcmp(a->attr.name, "gc_segment_mode"))
> @@ -446,6 +468,35 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>  		return ret ? ret : count;
>  	}
>  
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +	if (!strcmp(a->attr.name, "compress_extension")) {
> +		char *name = strim((char *)buf);
> +		bool set = true, cmpr;
> +
> +		if (!strncmp(name, "[c]", 3))
> +			cmpr = true;
> +		else if (!strncmp(name, "[n]", 3))
> +			cmpr = false;
> +		else
> +			return -EINVAL;
> +
> +		name += 3;
> +
> +		if (*name == '!') {
> +			name++;
> +			set = false;
> +		}
> +
> +		if (!strlen(name) || strlen(name) >= F2FS_EXTENSION_LEN)
> +			return -EINVAL;
> +
> +		f2fs_down_write(&sbi->sb_lock);
> +		ret = f2fs_update_compress_extension(sbi, name, cmpr, set);
> +		f2fs_up_write(&sbi->sb_lock);
> +		return ret ? ret : count;
> +	}
> +#endif
> +
>  	if (!strcmp(a->attr.name, "ckpt_thread_ioprio")) {
>  		const char *name = strim((char *)buf);
>  		struct ckpt_req_control *cprc = &sbi->cprc_info;
> @@ -785,15 +836,16 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
>  			const char *buf, size_t count)
>  {
>  	ssize_t ret;
> -	bool gc_entry = (!strcmp(a->attr.name, "gc_urgent") ||
> -					a->struct_type == GC_THREAD);
> +	bool need_lock = (!strcmp(a->attr.name, "gc_urgent") ||
> +					a->struct_type == GC_THREAD ||
> +					a->struct_type == MOUNT_INFO);
>  
> -	if (gc_entry) {
> +	if (need_lock) {
>  		if (!down_read_trylock(&sbi->sb->s_umount))
>  			return -EAGAIN;
>  	}
>  	ret = __sbi_store(a, sbi, buf, count);
> -	if (gc_entry)
> +	if (need_lock)
>  		up_read(&sbi->sb->s_umount);
>  
>  	return ret;
> @@ -942,6 +994,9 @@ static struct f2fs_attr f2fs_attr_##name = __ATTR(name, 0444, name##_show, NULL)
>  #define ATGC_INFO_RW_ATTR(name, elname)				\
>  	F2FS_RW_ATTR(ATGC_INFO, atgc_management, name, elname)
>  
> +#define MOUNT_INFO_RW_ATTR(name, elname)			\
> +	F2FS_RW_ATTR(MOUNT_INFO, f2fs_mount_info, name, elname)
> +
>  /* GC_THREAD ATTR */
>  GC_THREAD_RW_ATTR(gc_urgent_sleep_time, urgent_sleep_time);
>  GC_THREAD_RW_ATTR(gc_min_sleep_time, min_sleep_time);
> @@ -1008,6 +1063,7 @@ F2FS_SBI_GENERAL_RW_ATTR(compr_saved_block);
>  F2FS_SBI_GENERAL_RW_ATTR(compr_new_inode);
>  F2FS_SBI_GENERAL_RW_ATTR(compress_percent);
>  F2FS_SBI_GENERAL_RW_ATTR(compress_watermark);
> +MOUNT_INFO_RW_ATTR(compress_extension, extensions);
>  #endif
>  /* atomic write */
>  F2FS_SBI_GENERAL_RO_ATTR(current_atomic_write);
> @@ -1181,6 +1237,7 @@ static struct attribute *f2fs_attrs[] = {
>  	ATTR_LIST(compr_new_inode),
>  	ATTR_LIST(compress_percent),
>  	ATTR_LIST(compress_watermark),
> +	ATTR_LIST(compress_extension),
>  #endif
>  	/* For ATGC */
>  	ATTR_LIST(atgc_candidate_ratio),
> -- 
> 2.40.1