From patchwork Fri Aug 24 18:53:03 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josef Bacik X-Patchwork-Id: 1372331 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 46B733FC33 for ; Fri, 24 Aug 2012 18:47:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755090Ab2HXSry (ORCPT ); Fri, 24 Aug 2012 14:47:54 -0400 Received: from mx2.fusionio.com ([66.114.96.31]:48757 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752155Ab2HXSrw (ORCPT ); Fri, 24 Aug 2012 14:47:52 -0400 X-ASG-Debug-ID: 1345834071-0421b53abf9c4d0001-6jHSXT Received: from mail1.int.fusionio.com (mail1.int.fusionio.com [10.101.1.21]) by mx2.fusionio.com with ESMTP id wwoSsNKfeAWfRDQq (version=TLSv1 cipher=AES128-SHA bits=128 verify=NO) for ; Fri, 24 Aug 2012 12:47:51 -0600 (MDT) X-Barracuda-Envelope-From: JBacik@fusionio.com Received: from localhost (24.211.209.217) by mail.fusionio.com (10.101.1.19) with Microsoft SMTP Server (TLS) id 8.3.83.0; Fri, 24 Aug 2012 12:47:50 -0600 From: Josef Bacik To: Subject: [PATCH] Btrfs: fix deadlock with freeze and sync V2 Date: Fri, 24 Aug 2012 14:53:03 -0400 X-ASG-Orig-Subj: [PATCH] Btrfs: fix deadlock with freeze and sync V2 Message-ID: <1345834383-2172-1-git-send-email-jbacik@fusionio.com> X-Mailer: git-send-email 1.7.7.6 MIME-Version: 1.0 X-Barracuda-Connect: mail1.int.fusionio.com[10.101.1.21] X-Barracuda-Start-Time: 1345834071 X-Barracuda-Encrypted: AES128-SHA X-Barracuda-URL: http://10.101.1.181:8000/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at fusionio.com X-Barracuda-Spam-Score: 0.00 X-Barracuda-Spam-Status: No, SCORE=0.00 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.106601 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org We can deadlock with freeze right now because we unconditionally start a transaction in our ->sync_fs() call. To fix this just check and see if we have a running transaction to commit. This saves us from the deadlock because at this point we'll have the umount sem for the sb so we're safe from freezes coming in after we've done our check. With this patch the freeze xfstests no longer deadlocks. Thanks, Signed-off-by: Josef Bacik Reviewed-by: Liu Bo --- V1->V2: got a little overzealous and cleaned up the ret thing without actually removing the now unused ret variable. fs/btrfs/super.c | 13 +++++++++---- 1 files changed, 9 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 7b65fe8..83d6f9f 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -838,7 +838,6 @@ int btrfs_sync_fs(struct super_block *sb, int wait) struct btrfs_trans_handle *trans; struct btrfs_fs_info *fs_info = btrfs_sb(sb); struct btrfs_root *root = fs_info->tree_root; - int ret; trace_btrfs_sync_fs(wait); @@ -849,11 +848,17 @@ int btrfs_sync_fs(struct super_block *sb, int wait) btrfs_wait_ordered_extents(root, 0, 0); - trans = btrfs_start_transaction(root, 0); + spin_lock(&fs_info->trans_lock); + if (!fs_info->running_transaction) { + spin_unlock(&fs_info->trans_lock); + return 0; + } + spin_unlock(&fs_info->trans_lock); + + trans = btrfs_join_transaction(root); if (IS_ERR(trans)) return PTR_ERR(trans); - ret = btrfs_commit_transaction(trans, root); - return ret; + return btrfs_commit_transaction(trans, root); } static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)