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Date:   Fri, 28 Oct 2022 11:46:30 +0800
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Subject: Re: [PATCH v2 2/2] f2fs: introducr gc_urgent_idle_remaining sysfs
 node and mark gc_urgent_high_remaining node deprecated
Content-Language: en-US
To:     Jaegeuk Kim <jaegeuk@kernel.org>
Cc:     Yangtao Li <frank.li@vivo.com>,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
References: <20221025065025.35017-1-frank.li@vivo.com>
 <20221025065025.35017-2-frank.li@vivo.com>
 <cd6d15e3-b692-d3c1-0f01-33e632f5f94c@kernel.org>
 <Y1tLEVYQjj2qC3I7@google.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <Y1tLEVYQjj2qC3I7@google.com>
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On 2022/10/28 11:22, Jaegeuk Kim wrote:
> On 10/28, Chao Yu wrote:
>> 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.
> 
> I feel that this is not a super critical node, so how about just removing it?

Only Android is using this inferface, right?

Any plan to adjust related code from Android side?

Thanks,

> 
>>
>> 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),