linux-kernel - Re: [PATCH 4/6] f2fs: don't set FI_PREALLOCATED

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Date:   Mon, 11 Dec 2023 14:08:41 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>
Subject: Re: [PATCH 4/6] f2fs: don't set FI_PREALLOCATED_ALL for partial write

On 12/10, Chao Yu wrote:
> In f2fs_preallocate_blocks(), if it is partial write in 4KB, it's not
> necessary to call f2fs_map_blocks() and set FI_PREALLOCATED_ALL flag.
> 
> Cc: Eric Biggers <ebiggers@...gle.com>
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
>  fs/f2fs/file.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 5c2f99ada6be..1a3c29a9a6a0 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4561,13 +4561,14 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter,
>  			return ret;
>  	}
>  
> -	/* Do not preallocate blocks that will be written partially in 4KB. */
>  	map.m_lblk = F2FS_BLK_ALIGN(pos);
>  	map.m_len = F2FS_BYTES_TO_BLK(pos + count);
> -	if (map.m_len > map.m_lblk)
> -		map.m_len -= map.m_lblk;
> -	else

		return 0;

We just need the above?

> -		map.m_len = 0;
> +
> +	/* Do not preallocate blocks that will be written partially in 4KB. */
> +	if (map.m_len <= map.m_lblk)
> +		return 0;
> +
> +	map.m_len -= map.m_lblk;
>  	map.m_may_create = true;
>  	if (dio) {
>  		map.m_seg_type = f2fs_rw_hint_to_seg_type(inode->i_write_hint);
> -- 
> 2.40.1