linux-kernel - Re: [f2fs-dev] [PATCH 1/3] f2fs: call flush_dcache

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Date:	Thu, 20 Nov 2014 15:04:10 +0900
From:	Changman Lee <cm224.lee@...sung.com>
To:	Jaegeuk Kim <jaegeuk@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 1/3] f2fs: call flush_dcache_page when the page
	was updated

Hi Jaegeuk,

We should call flush_dcache_page before kunmap because the purpose of the cache flush is to address aliasing problem related to virtual address.

On Wed, Nov 19, 2014 at 02:35:08PM -0800, Jaegeuk Kim wrote:
> Whenever f2fs updates mapped pages, it needs to call flush_dcache_page.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  fs/f2fs/dir.c    | 7 ++++++-
>  fs/f2fs/inline.c | 4 +++-
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index 5a49995..312fbfc 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -287,8 +287,10 @@ void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
>  	f2fs_wait_on_page_writeback(page, type);
>  	de->ino = cpu_to_le32(inode->i_ino);
>  	set_de_type(de, inode);
> -	if (!f2fs_has_inline_dentry(dir))
> +	if (!f2fs_has_inline_dentry(dir)) {
>  		kunmap(page);
> +		flush_dcache_page(page);
> +	}
>  	set_page_dirty(page);
>  	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
>  	mark_inode_dirty(dir);
> @@ -366,6 +368,7 @@ static int make_empty_dir(struct inode *inode,
>  	do_make_empty_dir(inode, parent, &d);
>  
>  	kunmap_atomic(dentry_blk);
> +	flush_dcache_page(dentry_page);
>  
>  	set_page_dirty(dentry_page);
>  	f2fs_put_page(dentry_page, 1);
> @@ -579,6 +582,7 @@ fail:
>  		clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
>  	}
>  	kunmap(dentry_page);
> +	flush_dcache_page(dentry_page);
>  	f2fs_put_page(dentry_page, 1);
>  	return err;
>  }
> @@ -661,6 +665,7 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
>  			NR_DENTRY_IN_BLOCK,
>  			0);
>  	kunmap(page); /* kunmap - pair of f2fs_find_entry */
> +	flush_dcache_page(page);
>  	set_page_dirty(page);
>  
>  	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> index f26fb87..8b7cc51 100644
> --- a/fs/f2fs/inline.c
> +++ b/fs/f2fs/inline.c
> @@ -45,8 +45,8 @@ void read_inline_data(struct page *page, struct page *ipage)
>  	src_addr = inline_data_addr(ipage);
>  	dst_addr = kmap_atomic(page);
>  	memcpy(dst_addr, src_addr, MAX_INLINE_DATA);
> -	flush_dcache_page(page);
>  	kunmap_atomic(dst_addr);
> +	flush_dcache_page(page);
>  	SetPageUptodate(page);
>  }
>  
> @@ -107,6 +107,7 @@ int f2fs_convert_inline_page(struct dnode_of_data *dn, struct page *page)
>  	dst_addr = kmap_atomic(page);
>  	memcpy(dst_addr, src_addr, MAX_INLINE_DATA);
>  	kunmap_atomic(dst_addr);
> +	flush_dcache_page(page);
>  	SetPageUptodate(page);
>  no_update:
>  	/* write data page to try to make data consistent */
> @@ -358,6 +359,7 @@ static int f2fs_convert_inline_dir(struct inode *dir, struct page *ipage,
>  					NR_INLINE_DENTRY * F2FS_SLOT_LEN);
>  
>  	kunmap_atomic(dentry_blk);
> +	flush_dcache_page(page);
>  	SetPageUptodate(page);
>  	set_page_dirty(page);
>  
> -- 
> 2.1.1
> 
> 
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