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

* Re: [f2fs-dev] Reply: Reply: Reply: [PATCH -next 2/4] f2fs: extent cache: support extent for no-compressed file
@ 2022-09-22  9:32 zhangqilong via Linux-f2fs-devel
  2022-09-22 10:14 ` Chao Yu
  0 siblings, 1 reply; 4+ messages in thread
From: zhangqilong via Linux-f2fs-devel @ 2022-09-22  9:32 UTC (permalink / raw)
  To: Chao Yu, jaegeuk; +Cc: linux-f2fs-devel

> 
> On 2022/9/22 12:54, zhangqilong wrote:
> >> On 2022/9/22 10:07, zhangqilong wrote:
> >>>> On 2022/9/22 0:00, zhangqilong wrote:
> >>>>>> 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
> >>>>>>>> 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);
> >>>>>>
> >>>>>
> >>>>> Hi,
> >>>>>
> >>>>> I get it. I think we could consider this flow.
> >>>>> But it will change the metadata of the file, is it was a little
> >> inappropriate?
> >>>>> Maybe users does not want to do that during being loaded and will
> >>>> refuse this change.
> >>>>
> >>>> I don't get it.
> >>>>
> >>>> IIUC, we can only load files into ro f2fs image w/ sload, and sload
> >>>> has updated largest extent for file, or am I missing something?
> >>>
> >>> Ah, maybe I misunderstood your idea just now. We could updated
> >> largest
> >>> extent for file when loading into ro f2fs image w/ sload, but it
> >>> will not solve situations 3) issue for the no-compressed file that
> >>> be
> >> mentioned previously.
> >>
> >> Why case 3) can happen? The data blocks should be allocated
> >> contiguously while sload loads file into image?
> >
> > That's what I thought before, it should allocated contiguously while
> > sload loads file into image. But I found that it may not be completely
> > continuous for the big file recently. It may contain several
> > discontinuous parts.
> 
> I doubt it was caused by hot/cold data separation strategy, but I guess the
> strategy is not necessary for ro image, can you look into it?

HI,

"Looking into hot/cold data separation strategy" is a little difficult for me
now but I will continuous attention and research it in the future.
In addition, concurrent writing of multiple files also is likely to cause this issue,
so I think it is valueable sometimes :).

Thanks,

> 
> Thanks,
> 
> >
> > Thanks,
> >
> >>
> >> Thanks,
> >>
> >>>
> >>> Thanks,
> >>>
> >>>>
> >>>> Thanks,
> >>>>
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>>> 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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