Re: [PATCH 2/2 v2] f2fs: add a case of no need to read a page in write begin

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 12/20, Yunlei He wrote:
> If the range we write cover the whole valid data in the last page,
> we do not need to read it.
> 
> Signed-off-by: Yunlei He <heyunlei@huawei.com>
> ---
>  fs/f2fs/data.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 9ac2625..303873f 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1715,6 +1715,9 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>  	if (len == PAGE_SIZE || PageUptodate(page))
>  		return 0;
>  
> +	if (!(pos & (PAGE_SIZE - 1)) && (pos + len) >= i_size_read(inode))

I added here:
		zero_user_segment(page, 0, PAGE_SIZE);

Otherwise, xfstests/f2fs/001 gives a failure.

Thanks,

> +		return 0;
> +
>  	if (blkaddr == NEW_ADDR) {
>  		zero_user_segment(page, 0, PAGE_SIZE);
>  		SetPageUptodate(page);
> @@ -1768,7 +1771,7 @@ static int f2fs_write_end(struct file *file,
>  	 * let generic_perform_write() try to copy data again through copied=0.
>  	 */
>  	if (!PageUptodate(page)) {
> -		if (unlikely(copied != PAGE_SIZE))
> +		if (unlikely(copied != len))
>  			copied = 0;
>  		else
>  			SetPageUptodate(page);
> -- 
> 2.10.1
> 
> 
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