linux-ext4 - Re: [PATCH 03/15] mke2fs: simplify inode table block counting

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Date:	Tue, 30 Nov 2010 13:01:31 +0100 (CET)
From:	Lukas Czerner <lczerner@...hat.com>
To:	Namhyung Kim <namhyung@...il.com>
cc:	Theodore Tso <tytso@....edu>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 03/15] mke2fs: simplify inode table block counting

On Mon, 29 Nov 2010, Namhyung Kim wrote:

> Simplify counting of inode table blocks in a block group using
> local variable 'ipb'. Otherwise the variable could be removed
> because there was no user of it.
> 
> Signed-off-by: Namhyung Kim <namhyung@...il.com>
> ---
>  misc/mke2fs.c |    7 ++-----
>  1 files changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> index 0980045..9fb5d5f 100644
> --- a/misc/mke2fs.c
> +++ b/misc/mke2fs.c
> @@ -320,11 +320,8 @@ static void write_inode_tables(ext2_filsys fs, int lazy_flag, int itable_zeroed)
>  
>  		if (lazy_flag) {
>  			ipb = fs->blocksize / EXT2_INODE_SIZE(fs->super);
> -			num = ((((fs->super->s_inodes_per_group -
> -				  ext2fs_bg_itable_unused(fs, i)) *
> -				 EXT2_INODE_SIZE(fs->super)) +
> -				EXT2_BLOCK_SIZE(fs->super) - 1) /
> -			       EXT2_BLOCK_SIZE(fs->super));
> +			num = (fs->super->s_inodes_per_group -
> +			       ext2fs_bg_itable_unused(fs, i) + ipb - 1) / ipb;
>  		}
>  		if (!lazy_flag || itable_zeroed) {
>  			/* The kernel doesn't need to zero the itable blocks */
> 

Hi,

I would rather add this macro into header file (lib/ext2fs/ext2fs.h
maybe?)

#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))

remoevd ipb variable because it is rather useless. And do something like
this ?

num = DIV_ROUND_UP((fs->super->s_inodes_per_group -
		    ext2fs_bg_itable_unused(fs, i)) *
		   EXT2_INODE_SIZE(fs->super), 
		   EXT2_BLOCK_SIZE(fs->super));

IMO it improves readability a lot and I am sure that there are other
places which may take advantage of the DIV_ROUND_UP macro.

Thanks!

-Lukas
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