From patchwork Wed Dec 12 15:17:42 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 205562 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40C992C0091 for ; Thu, 13 Dec 2012 02:17:56 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754106Ab2LLPRy (ORCPT ); Wed, 12 Dec 2012 10:17:54 -0500 Received: from cantor2.suse.de ([195.135.220.15]:41049 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753593Ab2LLPRy (ORCPT ); Wed, 12 Dec 2012 10:17:54 -0500 Received: from relay1.suse.de (unknown [195.135.220.254]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id 93673A51B8; Wed, 12 Dec 2012 16:17:52 +0100 (CET) Received: by quack.suse.cz (Postfix, from userid 1000) id 77FDE20665; Wed, 12 Dec 2012 16:17:51 +0100 (CET) From: Jan Kara To: Ted Tso Cc: linux-ext4@vger.kernel.org, Jan Kara , stable@vger.kernel.org Subject: [PATCH] jbd2: Fix assertion failure in jbd2_journal_flush() Date: Wed, 12 Dec 2012 16:17:42 +0100 Message-Id: <1355325462-26757-1-git-send-email-jack@suse.cz> X-Mailer: git-send-email 1.7.1 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org The following race is possible between start_this_handle() and someone calling jbd2_journal_flush(). Process A Process B start_this_handle(). if (journal->j_barrier_count) # false if (!journal->j_running_transaction) { #true read_unlock(&journal->j_state_lock); jbd2_journal_lock_updates() jbd2_journal_flush() write_lock(&journal->j_state_lock); if (journal->j_running_transaction) { # false ... wait for committing trans ... write_unlock(&journal->j_state_lock); ... write_lock(&journal->j_state_lock); if (!journal->j_running_transaction) { # true jbd2_get_transaction(journal, new_transaction); write_unlock(&journal->j_state_lock); goto repeat; # eventually blocks on j_barrier_count > 0 ... J_ASSERT(!journal->j_running_transaction); # fails We fix the race by rechecking j_barrier_count after reacquiring j_state_lock in exclusive mode. CC: stable@vger.kernel.org Reported-by:yjwsignal@empal.com Signed-off-by: Jan Kara --- fs/jbd2/transaction.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index a74ba46..6873d24 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -209,7 +209,8 @@ repeat: if (!new_transaction) goto alloc_transaction; write_lock(&journal->j_state_lock); - if (!journal->j_running_transaction) { + if (!journal->j_running_transaction && + !journal->j_barrier_count) { jbd2_get_transaction(journal, new_transaction); new_transaction = NULL; }