From: Eric Gouriou Subject: Re: [PATCH 1/2] ext4: remove a wrong BUG_ON in ext4_ext_convert_to_initialized Date: Fri, 9 Dec 2011 14:41:44 -0800 Message-ID: References: <1323235287-29806-1-git-send-email-xiaoqiangnk@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-ext4@vger.kernel.org, achender@linux.vnet.ibm.com, hughd@google.com, tytso@mit.edu To: Yongqiang Yang Return-path: Received: from mail-qy0-f174.google.com ([209.85.216.174]:37430 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862Ab1LIWlp convert rfc822-to-8bit (ORCPT ); Fri, 9 Dec 2011 17:41:45 -0500 Received: by qcqz2 with SMTP id z2so2551813qcq.19 for ; Fri, 09 Dec 2011 14:41:44 -0800 (PST) In-Reply-To: <1323235287-29806-1-git-send-email-xiaoqiangnk@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Dec 6, 2011 at 21:21, Yongqiang Yang wr= ote: > If a file is fallocated on a hole, map->m_lblk + map->m_len may be gr= eater > than ee_block + ee_len. Could you please detail a scenario that leads to this check being inval= id? As I'm to blame for the faulty BUG_ON I'd like to use this as an opport= unity to get properly edified. > Signed-off-by: Yongqiang Yang > --- > =C2=A0fs/ext4/extents.c | =C2=A0 =C2=A01 - > =C2=A01 files changed, 0 insertions(+), 1 deletions(-) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 6f0300e..29bb629 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -2943,7 +2943,6 @@ static int ext4_ext_convert_to_initialized(hand= le_t *handle, > =C2=A0 =C2=A0 =C2=A0 =C2=A0/* Pre-conditions */ > =C2=A0 =C2=A0 =C2=A0 =C2=A0BUG_ON(!ext4_ext_is_uninitialized(ex)); > =C2=A0 =C2=A0 =C2=A0 =C2=A0BUG_ON(!in_range(map->m_lblk, ee_block, ee= _len)); > - =C2=A0 =C2=A0 =C2=A0 BUG_ON(map->m_lblk + map->m_len > ee_block + e= e_len); =46or a bit I thought this would break the fast path logic, however it = gets protected by the checks marked /*L1*/ and /*L2*/ since m_lblk =3D=3D ee= _block (L1) and m_len < ee_len (L2). Regards - Eric > > =C2=A0 =C2=A0 =C2=A0 =C2=A0/* > =C2=A0 =C2=A0 =C2=A0 =C2=A0 * Attempt to transfer newly initialized b= locks from the currently > -- > 1.7.5.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.ht= ml -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html