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Date: Tue, 20 Feb 2024 11:28:38 -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: <ZdT9ZmbCqMNk2nU4@google.com>
References: <20240207062546.3083870-1-chao@kernel.org>
 <ZcQbRzyvb8MNeOMB@google.com>
 <74933d5b-449e-4061-9571-799acbc42b43@kernel.org>
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On 02/19, Chao Yu wrote:
> On 2024/2/8 8:07, Jaegeuk Kim wrote:
> > 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.
> 
> It looks block layer output similar string:
> 
> cat /sys/block/<dev>/queue/scheduler
> mq-deadline kyber [bfq] none
> 
> Or, can we add extension entries into /sys/fs/f2fs/<dev>/compress_extensions/
> directory? like feature entries in /sys/fs/f2fs/<dev>/feature_list/.
> 
> e.g.
> 
> ls /sys/fs/f2fs/<dev>/compress_extensions/
> so dex
> 
> Show enable/disable to indicate current extension is in
> compress_extension/nocompress_extension array.
> 
> cat /sys/fs/f2fs/<dev>/compress_extensions/so
> enable
> 
> cat /sys/fs/f2fs/<dev>/compress_extensions/dex
> disable

How about adding all the file extentions in a separate entries and eash showing
the hot/cold/compression information together?

> 
> Thanks,
> 
> > 
> > > +		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