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Date: Mon, 18 Dec 2023 09:45:03 -0800
From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Zhiguo Niu <zhiguo.niu@unisoc.com>
Cc: chao@kernel.org, linux-f2fs-devel@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, niuzhiguo84@gmail.com,
	ke.wang@unisoc.com
Subject: Re: [PATCH V3] f2fs: show more discard status by sysfs
Message-ID: <ZYCFH4cyjjCVbpDF@google.com>
References: <1702897676-12851-1-git-send-email-zhiguo.niu@unisoc.com>
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In-Reply-To: <1702897676-12851-1-git-send-email-zhiguo.niu@unisoc.com>

On 12/18, Zhiguo Niu wrote:
> The current pending_discard attr just only shows the discard_cmd_cnt
> information. More discard status can be shown so that we can check
> them through sysfs when needed.
> 
> Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
> ---
> changes of v2: Improve the patch according to Chao's suggestions.
> changes of v3: Add a blank line for easy reading.
> ---
> ---
>  Documentation/ABI/testing/sysfs-fs-f2fs |  6 ++++++
>  fs/f2fs/sysfs.c                         | 19 +++++++++++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 36c3cb5..c6970e5 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -498,6 +498,12 @@ Description:	Show status of f2fs checkpoint in real time.
>  		CP_RESIZEFS_FLAG		0x00004000
>  		=============================== ==============================
>  
> +What:		/sys/fs/f2fs/<disk>/stat/discard_status
> +Date:		November 2023
> +Contact:	"Zhiguo Niu" <zhiguo.niu@unisoc.com>
> +Description:	Show status of f2fs discard in real time, including
> +		"issued discard","queued discard" and "undiscard blocks".
> +
>  What:		/sys/fs/f2fs/<disk>/ckpt_thread_ioprio
>  Date:		January 2021
>  Contact:	"Daeho Jeong" <daehojeong@google.com>
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 417fae96..312a4dc 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -134,6 +134,22 @@ static ssize_t cp_status_show(struct f2fs_attr *a,
>  	return sysfs_emit(buf, "%x\n", le32_to_cpu(F2FS_CKPT(sbi)->ckpt_flags));
>  }
>  
> +static ssize_t discard_status_show(struct f2fs_attr *a,
> +		struct f2fs_sb_info *sbi, char *buf)
> +{
> +	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
> +
> +	if (!dcc)
> +		return -EINVAL;
> +
> +	return sysfs_emit(buf, "%llu, %llu, %u\n",
> +			(unsigned long long)atomic_read(
> +				&dcc->issued_discard),
> +			(unsigned long long)atomic_read(
> +				&dcc->queued_discard),
> +			dcc->undiscard_blks);

We cannot do this since it needs one value per one entry.

> +}
> +
>  static ssize_t pending_discard_show(struct f2fs_attr *a,
>  		struct f2fs_sb_info *sbi, char *buf)
>  {
> @@ -1197,9 +1213,12 @@ static ssize_t f2fs_sb_feature_show(struct f2fs_attr *a,
>  
>  F2FS_GENERAL_RO_ATTR(sb_status);
>  F2FS_GENERAL_RO_ATTR(cp_status);
> +F2FS_GENERAL_RO_ATTR(discard_status);
> +
>  static struct attribute *f2fs_stat_attrs[] = {
>  	ATTR_LIST(sb_status),
>  	ATTR_LIST(cp_status),
> +	ATTR_LIST(discard_status),
>  	NULL,
>  };
>  ATTRIBUTE_GROUPS(f2fs_stat);
> -- 
> 1.9.1