Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753724AbcC3WK3 (ORCPT ); Wed, 30 Mar 2016 18:10:29 -0400 Received: from lists.s-osg.org ([54.187.51.154]:59346 "EHLO lists.s-osg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751367AbcC3WK1 (ORCPT ); Wed, 30 Mar 2016 18:10:27 -0400 Message-ID: <56FC4EC8.9090700@osg.samsung.com> Date: Wed, 30 Mar 2016 23:10:16 +0100 From: Luis de Bethencourt User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.8.0 MIME-Version: 1.0 To: fdmanana@gmail.com CC: "linux-kernel@vger.kernel.org" , Chris Mason , Josef Bacik , David Sterba , "linux-btrfs@vger.kernel.org" Subject: Re: [PATCH 2/2] btrfs: avoid overflowing f_bfree References: <1459371219-1815-1-git-send-email-luisbg@osg.samsung.com> <1459371219-1815-2-git-send-email-luisbg@osg.samsung.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1373 Lines: 42 On 30/03/16 22:48, Filipe Manana wrote: > On Wed, Mar 30, 2016 at 9:53 PM, Luis de Bethencourt > wrote: >> Since mixed block groups accounting isn't byte-accurate and f_bree is an >> unsigned integer, it could overflow. Avoid this. >> >> Signed-off-by: Luis de Bethencourt >> Suggested-by: David Sterba >> --- >> fs/btrfs/super.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c >> index bdca79c..93376d0 100644 >> --- a/fs/btrfs/super.c >> +++ b/fs/btrfs/super.c >> @@ -2101,6 +2101,11 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf) >> /* Account global block reserve as used, it's in logical size already */ >> spin_lock(&block_rsv->lock); >> buf->f_bfree -= block_rsv->size >> bits; > > You forgot to remove the line above, didn't you? > Shoot! Indeed I did, sorry. Thanks for noticing. Sending version 2. Luis >> + /* Mixed block groups accounting is not byte-accurate, avoid overflow */ >> + if (buf->f_bfree >= block_rsv->size >> bits) >> + buf->f_bfree -= block_rsv->size >> bits; >> + else >> + buf->f_bfree = 0; >> spin_unlock(&block_rsv->lock); >> >> buf->f_bavail = div_u64(total_free_data, factor); >> -- >> 2.5.3 >> >> --