Re: [PATCH v2 1/2] f2fs: use per-log target_bitmap to improve lookup performace of ssr allocation

[Chao Yu]

Jaegeuk, any comments for this serials?

On 2024/4/11 16:23, Chao Yu wrote:
> After commit 899fee36fac0 ("f2fs: fix to avoid data corruption by
> forbidding SSR overwrite"), valid block bitmap of current openned
> segment is fixed, let's introduce a per-log bitmap instead of temp
> bitmap to avoid unnecessary calculation overhead whenever allocating
> free slot w/ SSR allocator.
>
> Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
> ---
> v2:
> - rebase to last dev-test branch.
>   fs/f2fs/segment.c | 30 ++++++++++++++++++++++--------
>   fs/f2fs/segment.h |  1 +
>   2 files changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 6474b7338e81..af716925db19 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2840,31 +2840,39 @@ static int new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
>   	return 0;
>   }
>   
> -static int __next_free_blkoff(struct f2fs_sb_info *sbi,
> -					int segno, block_t start)
> +static void __get_segment_bitmap(struct f2fs_sb_info *sbi,
> +					unsigned long *target_map,
> +					int segno)
>   {
>   	struct seg_entry *se = get_seg_entry(sbi, segno);
>   	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
> -	unsigned long *target_map = SIT_I(sbi)->tmp_map;
>   	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
>   	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
>   	int i;
>   
>   	for (i = 0; i < entries; i++)
>   		target_map[i] = ckpt_map[i] | cur_map[i];
> +}
> +
> +static int __next_free_blkoff(struct f2fs_sb_info *sbi, unsigned long *bitmap,
> +					int segno, block_t start)
> +{
> +	__get_segment_bitmap(sbi, bitmap, segno);
>   
> -	return __find_rev_next_zero_bit(target_map, BLKS_PER_SEG(sbi), start);
> +	return __find_rev_next_zero_bit(bitmap, BLKS_PER_SEG(sbi), start);
>   }
>   
>   static int f2fs_find_next_ssr_block(struct f2fs_sb_info *sbi,
> -		struct curseg_info *seg)
> +					struct curseg_info *seg)
>   {
> -	return __next_free_blkoff(sbi, seg->segno, seg->next_blkoff + 1);
> +	return __find_rev_next_zero_bit(seg->target_map,
> +				BLKS_PER_SEG(sbi), seg->next_blkoff + 1);
>   }
>   
>   bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
>   {
> -	return __next_free_blkoff(sbi, segno, 0) < BLKS_PER_SEG(sbi);
> +	return __next_free_blkoff(sbi, SIT_I(sbi)->tmp_map, segno, 0) <
> +							BLKS_PER_SEG(sbi);
>   }
>   
>   /*
> @@ -2890,7 +2898,8 @@ static int change_curseg(struct f2fs_sb_info *sbi, int type)
>   
>   	reset_curseg(sbi, type, 1);
>   	curseg->alloc_type = SSR;
> -	curseg->next_blkoff = __next_free_blkoff(sbi, curseg->segno, 0);
> +	curseg->next_blkoff = __next_free_blkoff(sbi, curseg->target_map,
> +							curseg->segno, 0);
>   
>   	sum_page = f2fs_get_sum_page(sbi, new_segno);
>   	if (IS_ERR(sum_page)) {
> @@ -4635,6 +4644,10 @@ static int build_curseg(struct f2fs_sb_info *sbi)
>   				sizeof(struct f2fs_journal), GFP_KERNEL);
>   		if (!array[i].journal)
>   			return -ENOMEM;
> +		array[i].target_map = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE,
> +								GFP_KERNEL);
> +		if (!array[i].target_map)
> +			return -ENOMEM;
>   		if (i < NR_PERSISTENT_LOG)
>   			array[i].seg_type = CURSEG_HOT_DATA + i;
>   		else if (i == CURSEG_COLD_DATA_PINNED)
> @@ -5453,6 +5466,7 @@ static void destroy_curseg(struct f2fs_sb_info *sbi)
>   	for (i = 0; i < NR_CURSEG_TYPE; i++) {
>   		kfree(array[i].sum_blk);
>   		kfree(array[i].journal);
> +		kfree(array[i].target_map);
>   	}
>   	kfree(array);
>   }
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index e1c0f418aa11..10f3e44f036f 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -292,6 +292,7 @@ struct curseg_info {
>   	struct f2fs_summary_block *sum_blk;	/* cached summary block */
>   	struct rw_semaphore journal_rwsem;	/* protect journal area */
>   	struct f2fs_journal *journal;		/* cached journal info */
> +	unsigned long *target_map;		/* bitmap for SSR allocator */
>   	unsigned char alloc_type;		/* current allocation type */
>   	unsigned short seg_type;		/* segment type like CURSEG_XXX_TYPE */
>   	unsigned int segno;			/* current segment number */