RE: [f2fs-dev] [PATCH 12/12] f2fs: use extent_cache by default

[Chao Yu]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> Sent: Tuesday, June 30, 2015 2:40 AM
> To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 12/12] f2fs: use extent_cache by default
> 
> We don't need to handle the duplicate extent infot showrmation.

information?

> 
> The integrated rule is:
>  - update on-disk extent with largest one tracked by in-memory extent_cache
>  - destroy extent_tree for the truncation case
>  - drop per-inode extent_cache by shrinker
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>

[snip]

> @@ -538,7 +427,11 @@ static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
>  		}
>  	}
> 
> -	return __attach_extent_node(sbi, et, ei, parent, p);
> +	en = __attach_extent_node(sbi, et, ei, parent, p);
> +update_out:
> +	if (en && en->ei.len > et->largest.len)
> +		et->largest = en->ei;

IMO, it's better to update cached_en here if it is invalid in
__detach_extent_node, then cached_en and largest may point different
extent info, it can expand our region of first level extent cache.

[snip]

> +
> +	/* free all extent info belong to this extent tree */
> +	f2fs_destroy_extent_node(inode);

How about returning number of freed extent node for tracing.

node_cnt = f2fs_destroy_extent_node(inode);

[snip]

> @@ -237,10 +237,11 @@ void update_inode(struct inode *inode, struct page *node_page)
>  	ri->i_size = cpu_to_le64(i_size_read(inode));
>  	ri->i_blocks = cpu_to_le64(inode->i_blocks);
> 
> -	read_lock(&F2FS_I(inode)->ext_lock);
> -	set_raw_extent(&F2FS_I(inode)->ext, &ri->i_ext);
> -	read_unlock(&F2FS_I(inode)->ext_lock);
> -
> +	if (F2FS_I(inode)->extent_tree)

Could extent cache destroy after above check?

Thanks,
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