From patchwork Wed Mar 30 20:53:39 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis de Bethencourt X-Patchwork-Id: 8705161 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 6DEA9C0553 for ; Wed, 30 Mar 2016 20:54:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9217B20357 for ; Wed, 30 Mar 2016 20:54:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE34E2035E for ; Wed, 30 Mar 2016 20:54:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753653AbcC3Uxw (ORCPT ); Wed, 30 Mar 2016 16:53:52 -0400 Received: from lists.s-osg.org ([54.187.51.154]:59318 "EHLO lists.s-osg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753536AbcC3Uxv (ORCPT ); Wed, 30 Mar 2016 16:53:51 -0400 Received: from snow.seri.co.uk (cpc9-slam5-2-0-cust824.2-4.cable.virginm.net [81.108.163.57]) by lists.s-osg.org (Postfix) with ESMTPSA id 0F6944632A; Wed, 30 Mar 2016 13:53:47 -0700 (PDT) From: Luis de Bethencourt To: linux-kernel@vger.kernel.org Cc: clm@fb.com, jbacik@fb.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, Luis de Bethencourt Subject: [PATCH 2/2] btrfs: avoid overflowing f_bfree Date: Wed, 30 Mar 2016 21:53:39 +0100 Message-Id: <1459371219-1815-2-git-send-email-luisbg@osg.samsung.com> X-Mailer: git-send-email 2.5.1 In-Reply-To: <1459371219-1815-1-git-send-email-luisbg@osg.samsung.com> References: <1459371219-1815-1-git-send-email-luisbg@osg.samsung.com> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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; + /* 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);