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

[Chao Yu <chao@kernel.org>]

On 2022/9/21 21:57, zhangqilong wrote:
>> 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?
> 
> Hi,
> 
> I am sorry, I don't fully understand what you mean. I want to show that the extent of file in readonly
> format f2fs image could not existed or can't covered other parts that contain continuous blocks.

Well, I mean the extent should be updated due to below flow? during
the file was loaded into a formated f2fs image w/ ro feature.

- f2fs_sload
  - build_directory
   - f2fs_build_file

	if (!c.compress.enabled || (c.feature & cpu_to_le32(F2FS_FEATURE_RO)))
		update_largest_extent(sbi, de->ino);

Thanks,

> Whether it exists or not, we will not change or update largest extent during sload in a ro f2fs image.
> 
> Thanks,
> 
>>
>> 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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