Re: [PATCH] f2fs: fix to truncate inline data past EOF

[Jaegeuk Kim]

Hi Chao,

On Thu, Mar 05, 2015 at 05:41:32PM +0800, Chao Yu wrote:
> Previously if inode is with inline data, we will try to invalid partial inline
> data in page #0 when we truncate size of inode in truncate_partial_data_page().
> And then we set page #0 to dirty, after this we can synchronize inode page with
> page #0 at ->writepage().
> 
> But sometimes we will fail to operate page #0 in truncate_partial_data_page()
> due to below reason:
> a) if offset is zero, we will skip setting page #0 to dirty.
> b) if page #0 is not uptodate, we will fail to update it as it has no mapping
> data.
> 
> So with following operations, we will meet recent data which should be
> truncated.
> 
> 1.write inline data to file
> 2.sync first data page to inode page
> 3.truncate file size to 0
> 4.truncate file size to max_inline_size
> 5.echo 1 > /proc/sys/vm/drop_caches
> 6.read file --> meet original inline data which is remained in inode page.
> 
> This patch renames truncate_inline_data() to truncate_inline_inode() for code
> readability, then intruduces new truncate_inline_data() and use it to truncate
> inline data in page #0 and inode page in truncate_partial_data_page() for
> fixing.
> 
> Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> ---
>  fs/f2fs/f2fs.h   |  1 +
>  fs/f2fs/file.c   | 13 ++++++++-----
>  fs/f2fs/inline.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
>  3 files changed, 61 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 511d6cd..55dbbe7 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1754,6 +1754,7 @@ extern struct kmem_cache *inode_entry_slab;
>   */
>  bool f2fs_may_inline(struct inode *);
>  void read_inline_data(struct page *, struct page *);
> +int truncate_inline_data(struct inode *, u64 from);
>  int f2fs_read_inline_data(struct inode *, struct page *);
>  int f2fs_convert_inline_page(struct dnode_of_data *, struct page *);
>  int f2fs_convert_inline_inode(struct inode *);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index f1341c7..6c4443e 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -461,6 +461,9 @@ static int truncate_partial_data_page(struct inode *inode, u64 from)
>  	unsigned offset = from & (PAGE_CACHE_SIZE - 1);
>  	struct page *page;
>  
> +	if (f2fs_has_inline_data(inode))
> +		return 0;
> +
>  	if (!offset)
>  		return 0;
>  
> @@ -497,14 +500,14 @@ int truncate_blocks(struct inode *inode, u64 from, bool lock)
>  	if (lock)
>  		f2fs_lock_op(sbi);
>  
> -	ipage = get_node_page(sbi, inode->i_ino);
> -	if (IS_ERR(ipage)) {
> -		err = PTR_ERR(ipage);
> +	if (f2fs_has_inline_data(inode)) {
> +		err = truncate_inline_data(inode, from);
>  		goto out;
>  	}
>  
> -	if (f2fs_has_inline_data(inode)) {
> -		f2fs_put_page(ipage, 1);
> +	ipage = get_node_page(sbi, inode->i_ino);
> +	if (IS_ERR(ipage)) {
> +		err = PTR_ERR(ipage);
>  		goto out;
>  	}
>  
> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> index 4ba9732..a8189c92 100644
> --- a/fs/f2fs/inline.c
> +++ b/fs/f2fs/inline.c
> @@ -50,10 +50,57 @@ void read_inline_data(struct page *page, struct page *ipage)
>  	SetPageUptodate(page);
>  }
>  
> -static void truncate_inline_data(struct page *ipage)
> +static void truncate_inline_inode(struct page *ipage, u64 from)
>  {
> +	void *addr = inline_data_addr(ipage);
> +
>  	f2fs_wait_on_page_writeback(ipage, NODE);
> -	memset(inline_data_addr(ipage), 0, MAX_INLINE_DATA);
> +	memset(addr + from, 0, MAX_INLINE_DATA - from);
> +}
> +
> +int truncate_inline_data(struct inode *inode, u64 from)
> +{
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> +	struct page *page, *ipage;
> +	void *addr;
> +	int err = 0;
> +
> +	/*
> +	 * we should never truncate inline data past max inline data size,
> +	 * because we always convert inline inode to normal one before
> +	 * truncating real data if new size is past max inline data size.
> +	 */
> +	f2fs_bug_on(sbi, from > MAX_INLINE_DATA);
> +
> +	if (from == MAX_INLINE_DATA)
> +		return 0;
> +
> +	page = grab_cache_page(inode->i_mapping, 0);
> +	if (!page)
> +		return -ENOMEM;

Do we need to grab and read #0 page?
How about checking its cached page after on-disk truncation?

1. page = get_node_page()
2. check_inline
3. truncate_inline_inode
4. f2fs_put_page(ipage)

5. truncate_partial_data_page(inode, from, force)
	if (!offset && !force)
 		return 0;

> +
> +	ipage = get_node_page(sbi, inode->i_ino);
> +	if (IS_ERR(ipage)) {
> +		err = PTR_ERR(ipage);
> +		goto out;
> +	}
> +
> +	if (!f2fs_has_inline_data(inode)) {
> +		f2fs_put_page(ipage, 1);
> +		goto out;
> +	}
> +
> +	truncate_inline_inode(ipage, from);
> +	set_page_dirty(ipage);
> +
> +	read_inline_data(page, ipage);
> +	f2fs_put_page(ipage, 1);
> +
> +	addr = inline_data_addr(page);
> +	memset(addr + from, 0, MAX_INLINE_DATA - from);

It needs to do likewise truncate_partial_data_page.

Thanks,

> +out:
> +	f2fs_put_page(page, 1);
> +	return err;
>  }
>  
>  int f2fs_read_inline_data(struct inode *inode, struct page *page)
> @@ -131,7 +178,7 @@ no_update:
>  	set_inode_flag(F2FS_I(dn->inode), FI_APPEND_WRITE);
>  
>  	/* clear inline data and flag after data writeback */
> -	truncate_inline_data(dn->inode_page);
> +	truncate_inline_inode(dn->inode_page, 0);
>  clear_out:
>  	stat_dec_inline_inode(dn->inode);
>  	f2fs_clear_inline_inode(dn->inode);
> @@ -245,7 +292,7 @@ process_inline:
>  	if (f2fs_has_inline_data(inode)) {
>  		ipage = get_node_page(sbi, inode->i_ino);
>  		f2fs_bug_on(sbi, IS_ERR(ipage));
> -		truncate_inline_data(ipage);
> +		truncate_inline_inode(ipage, 0);
>  		f2fs_clear_inline_inode(inode);
>  		update_inode(inode, ipage);
>  		f2fs_put_page(ipage, 1);
> @@ -363,7 +410,7 @@ static int f2fs_convert_inline_dir(struct inode *dir, struct page *ipage,
>  	set_page_dirty(page);
>  
>  	/* clear inline dir and flag after data writeback */
> -	truncate_inline_data(ipage);
> +	truncate_inline_inode(ipage, 0);
>  
>  	stat_dec_inline_dir(dir);
>  	clear_inode_flag(F2FS_I(dir), FI_INLINE_DENTRY);
> -- 
> 2.3.1
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