From: "Aneesh Kumar K. V" Subject: Re: [PATCH] ext4: remove unnecessary operation in ext4_mb_normalize_group_request() Date: Fri, 26 Mar 2010 19:57:58 +0530 Message-ID: <87bpebnonl.fsf@linux.vnet.ibm.com> References: <87wrwzv732.fsf@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4 , "Theodore Ts'o" , Andreas Dilger , Dave Kleikamp To: jing zhang Return-path: Received: from e28smtp05.in.ibm.com ([122.248.162.5]:42569 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753684Ab0CZO2E (ORCPT ); Fri, 26 Mar 2010 10:28:04 -0400 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by e28smtp05.in.ibm.com (8.14.3/8.13.1) with ESMTP id o2QES1u1021041 for ; Fri, 26 Mar 2010 19:58:01 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o2QES1m11900692 for ; Fri, 26 Mar 2010 19:58:01 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o2QES0m2016269 for ; Sat, 27 Mar 2010 01:28:01 +1100 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, 26 Mar 2010 21:44:33 +0800, jing zhang wrote: > 2010/3/26, Aneesh Kumar K. V : > > On Thu, 25 Mar 2010 22:54:21 +0800, jing zhang wrote: > >> From: Jing Zhang > >> > >> 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 > >> Cc: Andreas Dilger > >> Cc: Dave Kleikamp > >> Cc: "Aneesh Kumar K. V" > >> Signed-off-by: Jing Zhang > >> > >> --- > >> > >> --- 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 > > > > Please check > 1, the 3 lines at the end of ext4_mb_group_or_file() > 2, the function name of this patch > What i wanted to mention was the BUG_ON is there to ensure that we don't call ext4_mb_normalize_group_request on non group enabled allocation context by programming mistake. Doing that would cause ac_g_ex.fe_len to change. So that BUG_ON is there to capture a programming error. -aneesh