[f2fs-dev] 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 2022/9/21 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.
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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