RE: [f2fs-dev] [PATCH 01/13] f2fs: should convert inline_data during the mkwrite

[Chao Yu]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> Sent: Wednesday, August 13, 2014 3:49 AM
> To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 01/13] f2fs: should convert inline_data during the mkwrite
> 
> If mkwrite is called to an inode having inline_data, it can overwrite the data
> index space as NEW_ADDR. (e.g., the first 4 bytes are coincidently zero)

Good catch!

As I did some simple tests, I found that thread will receive SIGBUS when
operating mmaped page exceed file size, so here, we will meet a inline data
inode only when we mkwrite the first page.
Please correct me if I'm wrong.

In this case, why not just do f2fs_read_inline_data & skip f2fs_reserve_block,
instead of converting inline_data and following f2fs_write_inline_data in
->writepage().

> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
>  fs/f2fs/data.c   |  2 +-
>  fs/f2fs/f2fs.h   |  2 +-
>  fs/f2fs/file.c   | 11 ++++++++---
>  fs/f2fs/inline.c | 20 ++++++++++++--------
>  4 files changed, 22 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 7aef28d..ac3ccc2 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -946,7 +946,7 @@ static int f2fs_write_begin(struct file *file, struct address_space
> *mapping,
> 
>  	f2fs_balance_fs(sbi);
>  repeat:
> -	err = f2fs_convert_inline_data(inode, pos + len);
> +	err = f2fs_convert_inline_data(inode, pos + len, NULL);
>  	if (err)
>  		goto fail;
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 790a073..c8288c9 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1439,7 +1439,7 @@ extern const struct inode_operations f2fs_special_inode_operations;
>   */
>  bool f2fs_may_inline(struct inode *);
>  int f2fs_read_inline_data(struct inode *, struct page *);
> -int f2fs_convert_inline_data(struct inode *, pgoff_t);
> +int f2fs_convert_inline_data(struct inode *, pgoff_t, struct page *);
>  int f2fs_write_inline_data(struct inode *, struct page *, unsigned int);
>  void truncate_inline_data(struct inode *, u64);
>  int recover_inline_data(struct inode *, struct page *);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 87cdac4..ecbdf6a 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -41,6 +41,11 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
> 
>  	sb_start_pagefault(inode->i_sb);
> 
> +	/* force to convert with normal data indices */
> +	err = f2fs_convert_inline_data(inode, MAX_INLINE_DATA + 1, page);
> +	if (err)
> +		goto out;
> +
>  	/* block allocation */
>  	f2fs_lock_op(sbi);
>  	set_new_dnode(&dn, inode, NULL, NULL, 0);
> @@ -533,7 +538,7 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
> 
>  	if ((attr->ia_valid & ATTR_SIZE) &&
>  			attr->ia_size != i_size_read(inode)) {
> -		err = f2fs_convert_inline_data(inode, attr->ia_size);
> +		err = f2fs_convert_inline_data(inode, attr->ia_size, NULL);
>  		if (err)
>  			return err;
> 
> @@ -622,7 +627,7 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len)
>  	loff_t off_start, off_end;
>  	int ret = 0;
> 
> -	ret = f2fs_convert_inline_data(inode, MAX_INLINE_DATA + 1);
> +	ret = f2fs_convert_inline_data(inode, MAX_INLINE_DATA + 1, NULL);
>  	if (ret)
>  		return ret;
> 
> @@ -678,7 +683,7 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
>  	if (ret)
>  		return ret;
> 
> -	ret = f2fs_convert_inline_data(inode, offset + len);
> +	ret = f2fs_convert_inline_data(inode, offset + len, NULL);
>  	if (ret)
>  		return ret;
> 
> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> index 5beecce..1ec512d 100644
> --- a/fs/f2fs/inline.c
> +++ b/fs/f2fs/inline.c
> @@ -124,9 +124,10 @@ out:
>  	return err;
>  }
> 
> -int f2fs_convert_inline_data(struct inode *inode, pgoff_t to_size)
> +int f2fs_convert_inline_data(struct inode *inode, pgoff_t to_size,
> +						struct page *page)
>  {
> -	struct page *page;
> +	struct page *new_page = page;
>  	int err;
> 
>  	if (!f2fs_has_inline_data(inode))
> @@ -134,17 +135,20 @@ int f2fs_convert_inline_data(struct inode *inode, pgoff_t to_size)
>  	else if (to_size <= MAX_INLINE_DATA)
>  		return 0;
> 
> -	page = grab_cache_page(inode->i_mapping, 0);
> -	if (!page)
> -		return -ENOMEM;
> +	if (!page || page->index != 0) {
> +		new_page = grab_cache_page(inode->i_mapping, 0);
> +		if (!new_page)
> +			return -ENOMEM;
> +	}
> 
> -	err = __f2fs_convert_inline_data(inode, page);
> -	f2fs_put_page(page, 1);
> +	err = __f2fs_convert_inline_data(inode, new_page);
> +	if (!page || page->index != 0)
> +		f2fs_put_page(new_page, 1);
>  	return err;
>  }
> 
>  int f2fs_write_inline_data(struct inode *inode,
> -			   struct page *page, unsigned size)
> +				struct page *page, unsigned size)
>  {
>  	void *src_addr, *dst_addr;
>  	struct page *ipage;
> --
> 1.8.5.2 (Apple Git-48)
> 
> 
> ------------------------------------------------------------------------------
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> Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

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