linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: introduce reserved_pin

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Message-ID: <c63deaf9-c567-46c4-a716-fae2b4736b88@kernel.org>
Date: Fri, 13 Jun 2025 13:31:56 +0800
From: Chao Yu <chao@...nel.org>
To: wangzijie <wangzijie1@...or.com>, linux-f2fs-devel@...ts.sourceforge.net
Cc: chao@...nel.org, jaegeuk@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [f2fs-dev] [PATCH] f2fs: introduce reserved_pin_section sysfs
 entry

On 2025/6/13 13:11, wangzijie wrote:
>> This patch introduces /sys/fs/f2fs/<dev>/reserved_pin_section for tuning
>> @needed parameter of has_not_enough_free_secs(), if we configure it w/
>> zero, it can avoid f2fs_gc() as much as possible while fallocating on
>> pinned file.
>>
>> Signed-off-by: Chao Yu <chao@...nel.org>
>> ---
>>   Documentation/ABI/testing/sysfs-fs-f2fs | 9 +++++++++
>>   fs/f2fs/f2fs.h                          | 3 +++
>>   fs/f2fs/file.c                          | 5 ++---
>>   fs/f2fs/super.c                         | 3 +++
>>   fs/f2fs/sysfs.c                         | 9 +++++++++
>>   5 files changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
>> index bf03263b9f46..c2a233f2a085 100644
>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
>> @@ -861,3 +861,12 @@ Description:	This is a read-only entry to show the value of sb.s_encoding_flags,
>>   		SB_ENC_STRICT_MODE_FL            0x00000001
>>   		SB_ENC_NO_COMPAT_FALLBACK_FL     0x00000002
>>   		============================     ==========
>> +
>> +What:		/sys/fs/f2fs/<disk>/reserved_pin_section
>> +Date:		June 2025
>> +Contact:	"Chao Yu" <chao@...nel.org>
>> +Description:	This threshold is used to control triggering garbage collection while
>> +		fallocating on pinned file, so, it can guarantee there is enough free
>> +		reserved section before preallocating on pinned file.
>> +		By default, the value is ovp_sections, especially, for zoned ufs, the
>> +		value is 1.
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 9333a22b9a01..fa27498202a3 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1724,6 +1724,9 @@ struct f2fs_sb_info {
>>   	/* for skip statistic */
>>   	unsigned long long skipped_gc_rwsem;		/* FG_GC only */
>>   
>> +	/* free sections reserved for pinned file */
>> +	unsigned int reserved_pin_section;
>> +
>>   	/* threshold for gc trials on pinned files */
>>   	unsigned short gc_pin_file_threshold;
>>   	struct f2fs_rwsem pin_sem;
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 696131e655ed..a909f79db178 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -1887,9 +1887,8 @@ static int f2fs_expand_inode_data(struct inode *inode, loff_t offset,
>>   			}
>>   		}
>>   
>> -		if (has_not_enough_free_secs(sbi, 0, f2fs_sb_has_blkzoned(sbi) ?
>> -			ZONED_PIN_SEC_REQUIRED_COUNT :
>> -			GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {
>> +		if (has_not_enough_free_secs(sbi, 0,
>> +				sbi->reserved_pin_section)) {
>>   			f2fs_down_write(&sbi->gc_lock);
>>   			stat_inc_gc_call_count(sbi, FOREGROUND);
>>   			err = f2fs_gc(sbi, &gc_control);
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 57adeff5ef25..48b97a95fd63 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -4975,6 +4975,9 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
>>   	sbi->last_valid_block_count = sbi->total_valid_block_count;
>>   	sbi->reserved_blocks = 0;
>>   	sbi->current_reserved_blocks = 0;
>> +	sbi->reserved_pin_section = f2fs_sb_has_blkzoned(sbi) ?
>> +			ZONED_PIN_SEC_REQUIRED_COUNT :
>> +			GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi));
>>   	limit_reserve_root(sbi);
>>   	adjust_unusable_cap_perc(sbi);
> 
> Hi Chao,
> It seems like we cannot use overprovision_segments(sbi) directly before f2fs_build_segment_manager().

Oops, ovp_segments is in f2fs_sm_info, I missed that, let me fix in v2.

Thanks,

>   
>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>> index 75134d69a0bd..51be7ffb38c5 100644
>> --- a/fs/f2fs/sysfs.c
>> +++ b/fs/f2fs/sysfs.c
>> @@ -824,6 +824,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>>   		return count;
>>   	}
>>   
>> +	if (!strcmp(a->attr.name, "reserved_pin_section")) {
>> +		if (t > GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))
>> +			return -EINVAL;
>> +		*ui = (unsigned int)t;
>> +		return count;
>> +	}
>> +
>>   	*ui = (unsigned int)t;
>>   
>>   	return count;
>> @@ -1130,6 +1137,7 @@ F2FS_SBI_GENERAL_RO_ATTR(unusable_blocks_per_sec);
>>   F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
>>   #endif
>>   F2FS_SBI_GENERAL_RW_ATTR(carve_out);
>> +F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section);
>>   
>>   /* STAT_INFO ATTR */
>>   #ifdef CONFIG_F2FS_STAT_FS
>> @@ -1323,6 +1331,7 @@ static struct attribute *f2fs_attrs[] = {
>>   	ATTR_LIST(last_age_weight),
>>   	ATTR_LIST(max_read_extent_count),
>>   	ATTR_LIST(carve_out),
>> +	ATTR_LIST(reserved_pin_section),
>>   	NULL,
>>   };
>>   ATTRIBUTE_GROUPS(f2fs);
>> -- 
>> 2.40.1
>>
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@...ts.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>