Re: [PATCH] ext4: remove unnecessary operation in ext4_mb_normalize_group_request()

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

On Thu, 25 Mar 2010 22:54:21 +0800, jing zhang <zj.barak@gmail.com> wrote:
> From: Jing Zhang <zj.barak@gmail.com>
> 
> Date: Wed Mar 25  22:55:04   2010
> 
> Checking bug seems not at right place, and the function itself should
> be inlined.
> 
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Andreas Dilger <adilger@sun.com>
> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
> Cc: "Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>
> Signed-off-by: Jing Zhang <zj.barak@gmail.com>
> 
> ---
> 
> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
> +++ ext4_mm_leak/mballoc-10.c	2010-03-25 22:44:00.000000000 +0800
> @@ -2786,9 +2786,7 @@ out_err:
>  static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
>  {
>  	struct super_block *sb = ac->ac_sb;
> -	struct ext4_locality_group *lg = ac->ac_lg;
> 
> -	BUG_ON(lg == NULL);
>  	if (EXT4_SB(sb)->s_stripe)
>  		ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_stripe;
>  	else

That BUG_ON is to ensure that the allocation context is actually having
a locality group which is needed for group allocation request.

-aneesh