From: jing zhang Subject: Re: [PATCH] ext4: remove unnecessary operation in ext4_mb_normalize_group_request() Date: Fri, 26 Mar 2010 22:37:49 +0800 Message-ID: References: <87wrwzv732.fsf@linux.vnet.ibm.com> <87bpebnonl.fsf@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-ext4 , "Theodore Ts'o" , Andreas Dilger , Dave Kleikamp To: "Aneesh Kumar K. V" Return-path: Received: from mail-gy0-f174.google.com ([209.85.160.174]:34283 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754035Ab0CZOhu (ORCPT ); Fri, 26 Mar 2010 10:37:50 -0400 Received: by gyg13 with SMTP id 13so214004gyg.19 for ; Fri, 26 Mar 2010 07:37:49 -0700 (PDT) In-Reply-To: <87bpebnonl.fsf@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 2010/3/26, Aneesh Kumar K. V : > 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 > Thank you, Aneesh, for good explanation in patience. Again, good weekend. Still in work? - zj