<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<p>Hi,</p>
<p>When journal flushing in ocfs2_commit_cache() fails, following umount procedure at stage of shutting journal may be blocked due to non-zero transactions number.</p>
<p>Once jbd2_journal_flush() fails, the journal will be marked as ABORT state inner JBD2. There is no way to come back afterwards.</p>
<p>So there is no chance to set transactions number to zero, thus, shutting journal may be blocked .<br>
</p>
<p><br>
</p>
<p>ocfs2_commit_thread()<br>
</p>
<p> ocfs2_commit_cache()</p>
<p> jbd2_journal_flush() -> failure takes journal into ABORT state, thus, transaction number will never set to zero<br>
</p>
<p><br>
</p>
<p>The back trace is cited blow:</p>
<p>[<ffffffff8109de0c>] kthread_stop+0x4c/0x150<br>
[<ffffffffc056a887>] ocfs2_journal_shutdown+0xa7/0x400 [ocfs2]<br>
[<ffffffffc059fbde>] ocfs2_dismount_volume+0xbe/0x4a0 [ocfs2]<br>
[<ffffffffc059fff7>] ocfs2_put_super+0x37/0xb0 [ocfs2]<br>
[<ffffffff8120534e>] generic_shutdown_super+0x7e/0x110<br>
[<ffffffff81205410>] kill_block_super+0x30/0x80<br>
[<ffffffff81205669>] deactivate_locked_super+0x59/0x90<br>
[<ffffffff812062ee>] deactivate_super+0x4e/0x70<br>
[<ffffffff81222423>] cleanup_mnt+0x43/0x90<br>
[<ffffffff812224c2>] __cleanup_mnt+0x12/0x20<br>
[<ffffffff8109c247>] task_work_run+0xb7/0xf0<br>
[<ffffffff81016f7c>] do_notify_resume+0x8c/0xa0<br>
[<ffffffff817f8384>] int_signal+0x12/0x17<br>
[<ffffffffffffffff>] 0xffffffffffffffff</p>
<p>Through crash debug tool, It can seen that j_num_trans field is set to 2.<br>
</p>
<p>struct ocfs2_journal {<br>
j_state = OCFS2_JOURNAL_IN_SHUTDOWN, <br>
j_journal = 0xffff8800b4926000, <br>
j_inode = 0xffff880122aba298, <br>
j_osb = 0xffff880093caa000, <br>
j_bh = 0xffff8800a09df888, <br>
j_num_trans = {<br>
counter = 0x2<br>
}, <br>
j_lock = {<br>
{<br>
rlock = {<br>
raw_lock = {<br>
{</p>
<p><br>
</p>
<p>To solve this issue, I propose a patch. Any comments will be welcomed.</p>
<p>Since journal has been marked as ABORT and flushing journal failure will free all corresponding buffer heads, it will be safe to directly set transactions number to zero.<br>
</p>
<p><br>
</p>
<p>From 98f42f5f52851ed84eb372a3e09a413a30ea2664 Mon Sep 17 00:00:00 2001<br>
From: gechangwei <a class="moz-txt-link-rfc2396E" href="mailto:ge.changwei@h3c.com">
<ge.changwei@h3c.com></a><br>
Date: Sat, 7 Jan 2017 19:48:13 +0800<br>
Subject: [PATCH] fix umount hang after flushing journal failure<br>
<br>
Signed-off-by: gechangwei <a class="moz-txt-link-rfc2396E" href="mailto:ge.changwei@h3c.com">
<ge.changwei@h3c.com></a><br>
---<br>
fs/ocfs2/journal.c | 1 +<br>
1 file changed, 1 insertion(+)<br>
<br>
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c<br>
index a244f14..dab2094 100644<br>
--- a/fs/ocfs2/journal.c<br>
+++ b/fs/ocfs2/journal.c<br>
@@ -326,6 +326,7 @@ static int ocfs2_commit_cache(struct ocfs2_super *osb)<br>
status = jbd2_journal_flush(journal->j_journal);<br>
jbd2_journal_unlock_updates(journal->j_journal);<br>
if (status < 0) {<br>
+ atomic_set(&journal->j_num_trans, 0);<br>
up_write(&journal->j_trans_barrier);<br>
mlog_errno(status);<br>
goto finally;<br>
-- <br>
2.5.1.windows.1<br>
<br>
</p>
<p><br>
</p>
<span style="font-size:7.5pt;font-family:华文细黑;color:gray"><span lang="EN-US">-------------------------------------------------------------------------------------------------------------------------------------<br>
</span>本邮件及其附件含有杭州华三通信技术有限公司的保密信息，仅限于发送给上面地址中列出<span lang="EN-US"><br>
</span>的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、<span lang="EN-US"><br>
</span>或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本<span lang="EN-US"><br>
</span>邮件！<span lang="EN-US"><br>
</span></span><span lang="EN-US" style="font-size:7.5pt;font-family:"Arial","sans-serif";color:gray">This e-mail and its attachments contain confidential information from H3C, which is
<br>
intended only for the person or entity whose address is listed above. Any use of the
<br>
information contained herein in any way (including, but not limited to, total or partial
<br>
disclosure, reproduction, or dissemination) by persons other than the intended <br>
recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender
<br>
by phone or email immediately and delete it!</span>
</body>
</html>