Re: [PATCH v2 2/2] f2fs: introducr gc_urgent_idle_remaining sysfs node and mark gc_urgent_high_remaining node deprecated

[Chao Yu <chao@kernel.org>]

On 2022/10/25 14:50, Yangtao Li wrote:
> Added a new sysfs node called gc_urgent_idle_remaining.
> The user can set the trial count limit for GC urgent and
> idle mode with this value. If GC thread gets to the limit,
> the mode will turn back to GC normal mode finally.
> 
> This method is not only applicable to gc_urgent_high,
> but applicable to all gc modes. Also mark
> gc_urgent_high_remaining as deprecated, so that the node
> can be removed in the future.
> 
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
>   Documentation/ABI/testing/sysfs-fs-f2fs |  8 ++++++++
>   fs/f2fs/f2fs.h                          |  6 ++++--
>   fs/f2fs/gc.c                            | 12 ++++++------
>   fs/f2fs/super.c                         |  2 +-
>   fs/f2fs/sysfs.c                         | 14 ++++++++++----
>   5 files changed, 29 insertions(+), 13 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 483639fb727b..859c4e53a846 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -598,6 +598,14 @@ Contact:	"Daeho Jeong" <daehojeong@google.com>
>   Description:	You can set the trial count limit for GC urgent high mode with this value.
>   		If GC thread gets to the limit, the mode will turn back to GC normal mode.
>   		By default, the value is zero, which means there is no limit like before.
> +		<deprecated>
> +
> +What:		/sys/fs/f2fs/<disk>/gc_urgent_idle_remaining
> +Date:		October 2022
> +Contact:	"Yangtao Li" <frank.li@vivo.com>
> +Description:	You can set the trial count limit for GC urgent and idle mode with this value.
> +		If GC thread gets to the limit, the mode will turn back to GC normal mode.
> +		By default, the value is zero, which means there is no limit like before.
>   
>   What:		/sys/fs/f2fs/<disk>/max_roll_forward_node_blocks
>   Date:		January 2022
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index e6355a5683b7..2bad69cf9fd9 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1734,8 +1734,10 @@ struct f2fs_sb_info {
>   	unsigned int cur_victim_sec;		/* current victim section num */
>   	unsigned int gc_mode;			/* current GC state */
>   	unsigned int next_victim_seg[2];	/* next segment in victim section */
> -	spinlock_t gc_urgent_high_lock;
> -	unsigned int gc_urgent_high_remaining;	/* remaining trial count for GC_URGENT_HIGH */
> +	spinlock_t gc_urgent_idle_lock;
> +	/* remaining trial count for GC_URGENT_* and GC_IDLE_* */
> +	unsigned int gc_urgent_idle_remaining;
> +	unsigned int gc_urgent_high_remaining;	/* deprecated */
>   
>   	/* for skip statistic */
>   	unsigned long long skipped_gc_rwsem;		/* FG_GC only */
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index e0ff99c7e3f2..0ed5b3c5922c 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -152,14 +152,14 @@ static int gc_thread_func(void *data)
>   		/* balancing f2fs's metadata periodically */
>   		f2fs_balance_fs_bg(sbi, true);
>   next:
> -		if (sbi->gc_mode == GC_URGENT_HIGH) {
> -			spin_lock(&sbi->gc_urgent_high_lock);
> -			if (sbi->gc_urgent_high_remaining) {
> -				sbi->gc_urgent_high_remaining--;
> -				if (!sbi->gc_urgent_high_remaining)
> +		if (sbi->gc_mode != GC_NORMAL) {
> +			spin_lock(&sbi->gc_urgent_idle_lock);
> +			if (sbi->gc_urgent_idle_remaining) {
> +				sbi->gc_urgent_idle_remaining--;
> +				if (!sbi->gc_urgent_idle_remaining)
>   					sbi->gc_mode = GC_NORMAL;
>   			}
> -			spin_unlock(&sbi->gc_urgent_high_lock);
> +			spin_unlock(&sbi->gc_urgent_idle_lock);
>   		}
>   		sb_end_write(sbi->sb);
>   
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 3834ead04620..f90a8c0a53ec 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -3616,7 +3616,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
>   	sbi->seq_file_ra_mul = MIN_RA_MUL;
>   	sbi->max_fragment_chunk = DEF_FRAGMENT_SIZE;
>   	sbi->max_fragment_hole = DEF_FRAGMENT_SIZE;
> -	spin_lock_init(&sbi->gc_urgent_high_lock);
> +	spin_lock_init(&sbi->gc_urgent_idle_lock);
>   	atomic64_set(&sbi->current_atomic_write, 0);
>   
>   	sbi->dir_level = DEF_DIR_LEVEL;
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index df27afd71ef4..2b1c653b37cf 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -531,10 +531,14 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>   		return count;
>   	}
>   
> -	if (!strcmp(a->attr.name, "gc_urgent_high_remaining")) {
> -		spin_lock(&sbi->gc_urgent_high_lock);
> -		sbi->gc_urgent_high_remaining = t;
> -		spin_unlock(&sbi->gc_urgent_high_lock);
> +	/* deprecated */
> +	if (!strcmp(a->attr.name, "gc_urgent_high_remaining"))
> +		return -EINVAL;

How about those users who has already used these interface... it breaks
the usage.

It needs to keep old interface and tag as deprecated, and recommend user
to use new interface you introduced.

e.g.:

What:           /sys/fs/f2fs/<disk>/features
Date:           July 2017
Contact:        "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:    <deprecated: should use /sys/fs/f2fs/<disk>/feature_list/
                 Shows all enabled features in current device.
                 Supported features:
                 encryption, blkzoned, extra_attr, projquota, inode_checksum,
                 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
                 verity, sb_checksum, casefold, readonly, compression, pin_file.

Thanks,

> +
> +	if (!strcmp(a->attr.name, "gc_urgent_idle_remaining")) {
> +		spin_lock(&sbi->gc_urgent_idle_lock);
> +		sbi->gc_urgent_idle_remaining = t;
> +		spin_unlock(&sbi->gc_urgent_idle_lock);
>   
>   		return count;
>   	}
> @@ -826,6 +830,7 @@ F2FS_RW_ATTR(FAULT_INFO_TYPE, f2fs_fault_info, inject_type, inject_type);
>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, data_io_flag, data_io_flag);
>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, node_io_flag, node_io_flag);
>   F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_urgent_high_remaining, gc_urgent_high_remaining);
> +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_urgent_idle_remaining, gc_urgent_idle_remaining);
>   F2FS_RW_ATTR(CPRC_INFO, ckpt_req_control, ckpt_thread_ioprio, ckpt_thread_ioprio);
>   F2FS_GENERAL_RO_ATTR(dirty_segments);
>   F2FS_GENERAL_RO_ATTR(free_segments);
> @@ -953,6 +958,7 @@ static struct attribute *f2fs_attrs[] = {
>   	ATTR_LIST(data_io_flag),
>   	ATTR_LIST(node_io_flag),
>   	ATTR_LIST(gc_urgent_high_remaining),
> +	ATTR_LIST(gc_urgent_idle_remaining),
>   	ATTR_LIST(ckpt_thread_ioprio),
>   	ATTR_LIST(dirty_segments),
>   	ATTR_LIST(free_segments),