linux-kernel - Re: [PATCH 1/2] f2fs: reorganize f2fs_vm_page

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Message-id: <1367203280.16581.3.camel@kjgkr>
Date:	Mon, 29 Apr 2013 11:41:20 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH 1/2] f2fs: reorganize f2fs_vm_page_mkwrite

Hi,

2013-04-28 (일), 09:04 +0900, Namjae Jeon:
> From: Namjae Jeon <namjae.jeon@...sung.com>
> 
> Few things can be changed in the default mkwrite function
> 1) Make file_update_time at the start before acquiring any lock
> 2) the condition page_offset(page) >= i_size_read(inode) should be
>  changed to page_offset(page) > i_size_read
> 3) Move wait_on_page_writeback.
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@...sung.com>
> Signed-off-by: Amit Sahrawat <a.sahrawat@...sung.com>
> ---
>  fs/f2fs/file.c |   12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 5cc4dd8..dc76f9b 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -63,9 +63,10 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
>  	f2fs_put_dnode(&dn);
>  	mutex_unlock_op(sbi, ilock);
>  
> +	file_update_time(vma->vm_file);

Should we update time even if error is occurred below?

>  	lock_page(page);
>  	if (page->mapping != inode->i_mapping ||
> -			page_offset(page) >= i_size_read(inode) ||
> +			page_offset(page) > i_size_read(inode) ||

Why? IMO, there was no problem.

>  			!PageUptodate(page)) {
>  		unlock_page(page);
>  		err = -EFAULT;
> @@ -76,10 +77,7 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
>  	 * check to see if the page is mapped already (no holes)
>  	 */
>  	if (PageMappedToDisk(page))
> -		goto out;
> -
> -	/* fill the page */
> -	wait_on_page_writeback(page);
> +		goto mapped;
>  
>  	/* page is wholly or partially inside EOF */
>  	if (((page->index + 1) << PAGE_CACHE_SHIFT) > i_size_read(inode)) {
> @@ -90,7 +88,9 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
>  	set_page_dirty(page);
>  	SetPageUptodate(page);
>  
> -	file_update_time(vma->vm_file);
> +mapped:
> +	/* fill the page */
> +	wait_on_page_writeback(page);
>  out:
>  	sb_end_pagefault(inode->i_sb);
>  	return block_page_mkwrite_return(err);

-- 
Jaegeuk Kim
Samsung

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