RE: [f2fs-dev] [PATCH 3/3] f2fs: load largest extent all the time

[Chao Yu <chao2.yu@samsung.com>]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@kernel.org]
> Sent: Tuesday, December 29, 2015 7:32 AM
> To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 3/3] f2fs: load largest extent all the time
> 
> Otherwise, we can get mismatched largest extent information.
> 
> One example is:
> 1. mount f2fs w/ extent_cache
> 2. make a small extent
> 3. umount
> 4. mount f2fs w/o extent_cache
> 5. update the largest extent
> 6. umount
> 7. mount f2fs w/ extent_cache
> 8. get the old extent made by #2

Good catch!

It's a pity to drop it since it may provide some help if we
can reuse it.

Thanks,

> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  fs/f2fs/extent_cache.c | 18 +++++++++++++-----
>  fs/f2fs/f2fs.h         |  2 +-
>  fs/f2fs/inode.c        |  3 ++-
>  3 files changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> index e7b6548..23e7c82 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -166,20 +166,27 @@ static void __drop_largest_extent(struct inode *inode,
>  		largest->len = 0;
>  }
> 
> -void f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
> +/* return true, if inode page is changed */
> +bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>  	struct extent_tree *et;
>  	struct extent_node *en;
>  	struct extent_info ei;
> 
> -	if (!f2fs_may_extent_tree(inode))
> -		return;
> +	if (!f2fs_may_extent_tree(inode)) {
> +		/* drop largest extent */
> +		if (i_ext && i_ext->len) {
> +			i_ext->len = 0;
> +			return true;
> +		}
> +		return false;
> +	}
> 
>  	et = __grab_extent_tree(inode);
> 
> -	if (!i_ext || le32_to_cpu(i_ext->len) < F2FS_MIN_EXTENT_LEN)
> -		return;
> +	if (!i_ext || !i_ext->len)
> +		return false;
> 
>  	set_extent_info(&ei, le32_to_cpu(i_ext->fofs),
>  		le32_to_cpu(i_ext->blk), le32_to_cpu(i_ext->len));
> @@ -196,6 +203,7 @@ void f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
>  	}
>  out:
>  	write_unlock(&et->lock);
> +	return false;
>  }
> 
>  static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index e04b2be..a339508 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2083,7 +2083,7 @@ void f2fs_leave_shrinker(struct f2fs_sb_info *);
>   * extent_cache.c
>   */
>  unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
> -void f2fs_init_extent_tree(struct inode *, struct f2fs_extent *);
> +bool f2fs_init_extent_tree(struct inode *, struct f2fs_extent *);
>  unsigned int f2fs_destroy_extent_node(struct inode *);
>  void f2fs_destroy_extent_tree(struct inode *);
>  bool f2fs_lookup_extent_cache(struct inode *, pgoff_t, struct extent_info *);
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index ec3fb32..e955008 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -138,7 +138,8 @@ static int do_read_inode(struct inode *inode)
>  	fi->i_pino = le32_to_cpu(ri->i_pino);
>  	fi->i_dir_level = ri->i_dir_level;
> 
> -	f2fs_init_extent_tree(inode, &ri->i_ext);
> +	if (f2fs_init_extent_tree(inode, &ri->i_ext))
> +		set_page_dirty(node_page);
> 
>  	get_inline_info(fi, ri);
> 
> --
> 2.5.4 (Apple Git-61)
> 
> 
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