Re: [f2fs-dev] [PATCH -next 2/4] f2fs: extent cache: support extent for no-compressed file

[Chao Yu <chao@kernel.org>]

On 2022/9/21 15:57, Zhang Qilong wrote:
> No-compressed file may suffer read performance issue due to it can't
> use extent cache or the largest extent in inode can't covered other
> parts of continuous blocks in readonly format f2fs image.
> 
> Now it won't build extent cacge tree for no-compressed file in
> readonly format f2fs image.
> 
> For readonly format f2fs image, maybe the no-compressed file don't
> have the largest extent, or it have more than one part which have

Why it can not have largest extent in f2fs_inode?

Thanks,

> internally continuous blocks. So we add extent cache tree for the
> no-compressed file in readonly format f2fs image.
> 
> The cache policy is almost same with compressed file. The difference
> is that, the no-compressed file part will set min-number of continuous
> blocks F2FS_MIN_EXTENT_LEN in order to reduce cache fragmentation.
> 
> Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
> ---
>   fs/f2fs/extent_cache.c | 52 ++++++++++++++++++++++++++++++++++--------
>   1 file changed, 42 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> index 387d53a61270..7e39381edca0 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -695,9 +695,12 @@ static void f2fs_update_extent_tree_range_compressed(struct inode *inode,
>   	set_extent_info(&ei, fofs, blkaddr, llen);
>   	ei.c_len = c_len;
>   
> -	if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
> +	if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en)) {
> +		if (!c_len && llen < F2FS_MIN_EXTENT_LEN)
> +			goto unlock_out;
>   		__insert_extent_tree(sbi, et, &ei,
>   				insert_p, insert_parent, leftmost);
> +	}
>   unlock_out:
>   	write_unlock(&et->lock);
>   }
> @@ -726,24 +729,53 @@ static unsigned int f2fs_cluster_blocks_are_contiguous(struct dnode_of_data *dn)
>   	return compressed ? i - 1 : i;
>   }
>   
> +/*
> + * check whether normal file blocks are contiguous, and add extent cache
> + * entry only if remained blocks are logically and physically contiguous.
> + */
> +static unsigned int f2fs_normal_blocks_are_contiguous(struct dnode_of_data *dn)
> +{
> +	int i = 0;
> +	struct inode *inode = dn->inode;
> +	block_t first_blkaddr = data_blkaddr(inode, dn->node_page,
> +						dn->ofs_in_node);
> +	unsigned int max_blocks = ADDRS_PER_PAGE(dn->node_page, inode)
> +					- dn->ofs_in_node;
> +
> +	for (i = 1; i < max_blocks; i++) {
> +		block_t blkaddr = data_blkaddr(inode, dn->node_page,
> +				dn->ofs_in_node + i);
> +
> +		if (!__is_valid_data_blkaddr(blkaddr) ||
> +				first_blkaddr + i != blkaddr)
> +			return i;
> +	}
> +
> +	return i;
> +}
> +
>   void f2fs_readonly_update_extent_cache(struct dnode_of_data *dn,
>   					pgoff_t index)
>   {
> -	unsigned int c_len = f2fs_cluster_blocks_are_contiguous(dn);
> +	unsigned int c_len = 0;
> +	unsigned int llen = 0;
>   	block_t blkaddr;
>   
> -	if (!c_len)
> -		return;
> -
>   	blkaddr = f2fs_data_blkaddr(dn);
> -	if (blkaddr == COMPRESS_ADDR)
> -		blkaddr = data_blkaddr(dn->inode, dn->node_page,
> +	if (f2fs_compressed_file(dn->inode)) {
> +		c_len = f2fs_cluster_blocks_are_contiguous(dn);
> +		if (!c_len)
> +			return;
> +		llen = F2FS_I(dn->inode)->i_cluster_size;
> +		if (blkaddr == COMPRESS_ADDR)
> +			blkaddr = data_blkaddr(dn->inode, dn->node_page,
>   					dn->ofs_in_node + 1);
> +	} else {
> +		llen = f2fs_normal_blocks_are_contiguous(dn);
> +	}
>   
>   	f2fs_update_extent_tree_range_compressed(dn->inode,
> -				index, blkaddr,
> -				F2FS_I(dn->inode)->i_cluster_size,
> -				c_len);
> +				index, blkaddr, llen, c_len);
>   }
>   #endif
>   


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