Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754934AbcC3Vs3 (ORCPT ); Wed, 30 Mar 2016 17:48:29 -0400 Received: from mail-ig0-f193.google.com ([209.85.213.193]:34595 "EHLO mail-ig0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753066AbcC3Vs1 (ORCPT ); Wed, 30 Mar 2016 17:48:27 -0400 MIME-Version: 1.0 Reply-To: fdmanana@gmail.com In-Reply-To: <1459371219-1815-2-git-send-email-luisbg@osg.samsung.com> References: <1459371219-1815-1-git-send-email-luisbg@osg.samsung.com> <1459371219-1815-2-git-send-email-luisbg@osg.samsung.com> Date: Wed, 30 Mar 2016 22:48:26 +0100 Message-ID: Subject: Re: [PATCH 2/2] btrfs: avoid overflowing f_bfree From: Filipe Manana To: Luis de Bethencourt Cc: "linux-kernel@vger.kernel.org" , Chris Mason , Josef Bacik , David Sterba , "linux-btrfs@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1595 Lines: 46 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? > + /* 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Filipe David Manana, "Reasonable men adapt themselves to the world. Unreasonable men adapt the world to themselves. That's why all progress depends on unreasonable men."