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

[zhangqilong via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

> 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.

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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