linux-ext4 - Re: [PATCH v3 4/6] ext4: convert to use i

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Date:   Fri, 10 Mar 2023 03:19:40 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Yangtao Li <frank.li@...o.com>
Cc:     xiang@...nel.org, chao@...nel.org, huyue2@...lpad.com,
        jefflexu@...ux.alibaba.com, tytso@....edu,
        adilger.kernel@...ger.ca, rpeterso@...hat.com, agruenba@...hat.com,
        mark@...heh.com, jlbec@...lplan.org, joseph.qi@...ux.alibaba.com,
        brauner@...nel.org, linux-erofs@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org,
        cluster-devel@...hat.com, ocfs2-devel@....oracle.com,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v3 4/6] ext4: convert to use i_blockmask()

On Thu, Mar 09, 2023 at 11:21:25PM +0800, Yangtao Li wrote:
> Use i_blockmask() to simplify code.
> 
> Signed-off-by: Yangtao Li <frank.li@...o.com>
> ---
> v3:
> -none
> v2:
> -convert to i_blockmask()
>  fs/ext4/inode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index d251d705c276..eec36520e5e9 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2218,7 +2218,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
>  {
>  	struct inode *inode = mpd->inode;
>  	int err;
> -	ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
> +	ext4_lblk_t blocks = (i_size_read(inode) + i_blockmask(inode))
>  							>> inode->i_blkbits;

Umm...  That actually asks for DIV_ROUND_UP(i_size_read_inode(), i_blocksize(inode)) -
compiler should bloody well be able to figure out that division by (1 << n) is
shift down by n and it's easier to follow that way...