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

[Chao Yu <chao@kernel.org>]

On 2022/9/21 20:14, zhangqilong wrote:
>> 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?
> 
> The following several situations may occur:
> 	1) Wrote w/o the extent when the filesystem is read-write fs.
> 
>      2) Largest extent have been drop after being re-wrote, or it have been split to smaller parts.
> 
>      3) The largest extent only covered one part of continuous blocks, like:
>        |------parts 1(continuous blocks)-----|----not continuous---|---------------------parts 2 (continuous blocks)-----------|---------|
>        The largest extent is part 2, but other parts (like part1, ) can't be mapped in readonly format f2fs image which should have been mapped.

largest extent of non-compressed file should be updated during sload
in a ro f2fs image?

Thanks,

> 
> 
> Thanks,
> 
>>
>> 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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