linux-kernel - Re: [PATCH v4 3/3] f2fs: introduce ipu

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Date:   Tue, 7 Feb 2023 10:50:46 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Yangtao Li <frank.li@...o.com>
Cc:     chao@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] f2fs: introduce ipu_mode sysfs node

On 02/06, Yangtao Li wrote:
> Add a ipu_mode sysfs node to show the current ipu policy as a string
> for readability, like we do in commit a3951cd199a5 ("f2fs: introduce
> gc_mode sysfs node").
> 
> Since we use ipu_policy as a bitmap, and the bitmap API parameter is
> unsigned long type data, let's change ipu_policy to unsigned long type.
> 
> Signed-off-by: Yangtao Li <frank.li@...o.com>
> ---
> v4:
> -rebase, no code change
>  Documentation/ABI/testing/sysfs-fs-f2fs |  6 ++++++
>  fs/f2fs/f2fs.h                          |  4 ++--
>  fs/f2fs/segment.h                       |  1 +
>  fs/f2fs/sysfs.c                         | 28 ++++++++++++++++++++++++-
>  4 files changed, 36 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 94132745ecbe..b2d8c1e84073 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -729,3 +729,9 @@ What:		/sys/fs/f2fs/<disk>/last_age_weight
>  Date:		January 2023
>  Contact:	"Ping Xiong" <xiongping1@...omi.com>
>  Description:	When DATA SEPARATION is on, it controls the weight of last data block age.
> +
> +What:		/sys/fs/f2fs/<disk>/ipu_mode
> +Date:		February 2023
> +Contact:	"Yangtao Li" <frank.li@...o.com>
> +Description:	Show the current ipu policy as a string.
> +		This is a read-only entry.
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 44f2d76525bf..b699ed74f438 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1070,7 +1070,7 @@ struct f2fs_sm_info {
>  
>  	struct list_head sit_entry_set;	/* sit entry set list */
>  
> -	unsigned int ipu_policy;	/* in-place-update policy */
> +	unsigned long ipu_policy;	/* in-place-update policy */
>  	unsigned int min_ipu_util;	/* in-place-update threshold */
>  	unsigned int min_fsync_blocks;	/* threshold for fsync */
>  	unsigned int min_seq_blocks;	/* threshold for sequential blocks */
> @@ -1322,7 +1322,7 @@ enum {
>  	MAX_TIME,
>  };
>  
> -/* Note that you need to keep synchronization with this gc_mode_names array */
> +/* Modification on enum should be synchronized with gc_mode_names array */
>  enum {
>  	GC_NORMAL,
>  	GC_IDLE_CB,
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 8ee5e5db9287..92c8be00d396 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -672,6 +672,7 @@ static inline int utilization(struct f2fs_sb_info *sbi)
>  
>  #define F2FS_IPU_DISABLE	0
>  
> +/* Modification on enum should be synchronized with ipu_mode_names array */
>  enum {
>  	F2FS_IPU_FORCE,
>  	F2FS_IPU_SSR,
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 3c3dae3ce84e..4a2d895cd52c 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -51,6 +51,17 @@ static const char *gc_mode_names[MAX_GC_MODE] = {
>  	"GC_URGENT_MID"
>  };
>  
> +static const char *ipu_mode_names[F2FS_IPU_MAX] = {
> +	"FORCE",
> +	"SSR",
> +	"UTIL",
> +	"SSR_UTIL",
> +	"FSYNC",
> +	"ASYNC",
> +	"NOCACHE",
> +	"HONOR_OPU_WRITE",
> +};
> +
>  struct f2fs_attr {
>  	struct attribute attr;
>  	ssize_t (*show)(struct f2fs_attr *a, struct f2fs_sb_info *sbi, char *buf);
> @@ -149,6 +160,19 @@ static ssize_t gc_mode_show(struct f2fs_attr *a,
>  	return sysfs_emit(buf, "%s\n", gc_mode_names[sbi->gc_mode]);
>  }
>  
> +static ssize_t ipu_mode_show(struct f2fs_attr *a,
> +		struct f2fs_sb_info *sbi, char *buf)
> +{
> +	int len = 0, i = 0;
> +
> +	if (SM_I(sbi)->ipu_policy == F2FS_IPU_DISABLE)
> +		return sysfs_emit(buf, "DISABLE\n");
> +
> +	for_each_set_bit(i, &SM_I(sbi)->ipu_policy, F2FS_IPU_MAX)
> +		len += scnprintf(buf + len, PAGE_SIZE - len, "%s\n", ipu_mode_names[i]);

I believe this would not be a good usecase for the sysfs entry. How about
putting the info in debugfs?

> +	return len;
> +}
> +
>  static ssize_t features_show(struct f2fs_attr *a,
>  		struct f2fs_sb_info *sbi, char *buf)
>  {
> @@ -711,7 +735,7 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>  			return -EINVAL;
>  		if (t && f2fs_lfs_mode(sbi))
>  			return -EINVAL;
> -		SM_I(sbi)->ipu_policy = (unsigned int)t;
> +		SM_I(sbi)->ipu_policy = t;
>  		return count;
>  	}
>  
> @@ -907,6 +931,7 @@ F2FS_GENERAL_RO_ATTR(mounted_time_sec);
>  F2FS_GENERAL_RO_ATTR(main_blkaddr);
>  F2FS_GENERAL_RO_ATTR(pending_discard);
>  F2FS_GENERAL_RO_ATTR(gc_mode);
> +F2FS_GENERAL_RO_ATTR(ipu_mode);
>  #ifdef CONFIG_F2FS_STAT_FS
>  F2FS_STAT_ATTR(STAT_INFO, f2fs_stat_info, cp_foreground_calls, cp_count);
>  F2FS_STAT_ATTR(STAT_INFO, f2fs_stat_info, cp_background_calls, bg_cp_count);
> @@ -997,6 +1022,7 @@ static struct attribute *f2fs_attrs[] = {
>  	ATTR_LIST(max_ordered_discard),
>  	ATTR_LIST(pending_discard),
>  	ATTR_LIST(gc_mode),
> +	ATTR_LIST(ipu_mode),
>  	ATTR_LIST(ipu_policy),
>  	ATTR_LIST(min_ipu_util),
>  	ATTR_LIST(min_fsync_blocks),
> -- 
> 2.25.1