From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D292C43334 for ; Sun, 2 Sep 2018 09:15:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1975620645 for ; Sun, 2 Sep 2018 09:15:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1975620645 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726193AbeIBNaQ (ORCPT ); Sun, 2 Sep 2018 09:30:16 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:48674 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726003AbeIBNaQ (ORCPT ); Sun, 2 Sep 2018 09:30:16 -0400 Received: from Beta.suse.asia (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by smtp2.provo.novell.com with ESMTP (NOT encrypted); Sun, 02 Sep 2018 03:15:03 -0600 From: Larry Chen To: mark@fasheh.com, jlbec@evilplan.org Cc: linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com, akpm@linux-foundation.org Subject: [PATCH V2] ocfs2: fix dead lock caused by ocfs2_defrag_extent Date: Sun, 2 Sep 2018 17:14:55 +0800 Message-Id: <20180902091455.23862-1-lchen@suse.com> X-Mailer: git-send-email 2.13.7 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ocfs2_defrag_extent may fall into dead lock. ocfs2_ioctl_move_extents ocfs2_ioctl_move_extents ocfs2_move_extents ocfs2_defrag_extent ocfs2_lock_allocators_move_extents ocfs2_reserve_clusters inode_lock GLOBAL_BITMAP_SYSTEM_INODE __ocfs2_flush_truncate_log inode_lock GLOBAL_BITMAP_SYSTEM_INODE As back trace shows above, ocfs2_reserve_clusters will call inode_lock against the global bitmap if local allocator has not sufficient cluters. Once global bitmap could meet the demand, ocfs2_reserve_cluster will return success with global bitmap locked. After ocfs2_reserve_cluster, if truncate log is full, __ocfs2_flush_truncate_log will definitely fall into dead lock because it needs to inode_lock global bitmap, which has already been locked. To fix this bug, we could remove from ocfs2_lock_allocators_move_extents the code which intends to lock global allocator, and put the removed code after __ocfs2_flush_truncate_log The ocfs2_lock_allocators_move_extents has been refered by 2 places, one is here, the other does not need the data allocator context, which means this patch does not affect the caller so far. Change log: 1. rename ocfs2_lock_allocators_move_extents to ocfs2_lock_meta_allocator_move_extents 2. add some comments Signed-off-by: Larry Chen --- fs/ocfs2/move_extents.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c index 7eb3b0a6347e..d85dc8a02bd6 100644 --- a/fs/ocfs2/move_extents.c +++ b/fs/ocfs2/move_extents.c @@ -162,7 +162,7 @@ static int __ocfs2_move_extent(handle_t *handle, * in some cases, we don't need to reserve clusters, just let data_ac * be NULL. */ -static int ocfs2_lock_allocators_move_extents(struct inode *inode, +static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode, struct ocfs2_extent_tree *et, u32 clusters_to_move, u32 extents_to_split, @@ -192,13 +192,6 @@ static int ocfs2_lock_allocators_move_extents(struct inode *inode, goto out; } - if (data_ac) { - ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac); - if (ret) { - mlog_errno(ret); - goto out; - } - } *credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el); @@ -257,10 +250,11 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context, } } - ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1, - &context->meta_ac, - &context->data_ac, - extra_blocks, &credits); + ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et, + *len, 1, + &context->meta_ac, + &context->data_ac, + extra_blocks, &credits); if (ret) { mlog_errno(ret); goto out; @@ -283,6 +277,21 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context, } } + /* + * Make sure ocfs2_reserve_cluster is called after + * __ocfs2_flush_truncate_log, otherwise, dead lock may happen. + * + * If ocfs2_reserve_cluster is called + * before __ocfs2_flush_truncate_log, dead lock on global bitmap + * may happen. + * + */ + ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac); + if (ret) { + mlog_errno(ret); + goto out_unlock_mutex; + } + handle = ocfs2_start_trans(osb, credits); if (IS_ERR(handle)) { ret = PTR_ERR(handle); @@ -600,9 +609,10 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context, } } - ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1, - &context->meta_ac, - NULL, extra_blocks, &credits); + ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et, + len, 1, + &context->meta_ac, + NULL, extra_blocks, &credits); if (ret) { mlog_errno(ret); goto out; -- 2.13.7