From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755614AbaIKMgR (ORCPT ); Thu, 11 Sep 2014 08:36:17 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51699 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755467AbaIKMeJ (ORCPT ); Thu, 11 Sep 2014 08:34:09 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Theodore Ts'o" Date: Thu, 11 Sep 2014 13:32:13 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 034/131] ext4: fix ext4_discard_allocated_blocks() if we can't allocate the pa struct In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 86f0afd463215fc3e58020493482faa4ac3a4d69 upstream. If there is a failure while allocating the preallocation structure, a number of blocks can end up getting marked in the in-memory buddy bitmap, and then not getting released. This can result in the following corruption getting reported by the kernel: EXT4-fs error (device sda3): ext4_mb_generate_buddy:758: group 1126, 12793 clusters in bitmap, 12729 in gd In that case, we need to release the blocks using mb_free_blocks(). Tested: fs smoke test; also demonstrated that with injected errors, the file system is no longer getting corrupted Google-Bug-Id: 16657874 Signed-off-by: "Theodore Ts'o" Signed-off-by: Ben Hutchings --- fs/ext4/mballoc.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3128,8 +3128,27 @@ static void ext4_mb_collect_stats(struct static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac) { struct ext4_prealloc_space *pa = ac->ac_pa; + struct ext4_buddy e4b; + int err; - if (pa && pa->pa_type == MB_INODE_PA) + if (pa == NULL) { + err = ext4_mb_load_buddy(ac->ac_sb, ac->ac_f_ex.fe_group, &e4b); + if (err) { + /* + * This should never happen since we pin the + * pages in the ext4_allocation_context so + * ext4_mb_load_buddy() should never fail. + */ + WARN(1, "mb_load_buddy failed (%d)", err); + return; + } + ext4_lock_group(ac->ac_sb, ac->ac_f_ex.fe_group); + mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start, + ac->ac_f_ex.fe_len); + ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group); + return; + } + if (pa->pa_type == MB_INODE_PA) pa->pa_free += ac->ac_b_ex.fe_len; }