Gechangwei
2017-Jan-07 12:01 UTC
[Ocfs2-devel] [PATCH] ocfs2/journal: fix umount hang after flushing journal failure
Hi,
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.
Once jbd2_journal_flush() fails, the journal will be marked as ABORT state inner
JBD2. There is no way to come back afterwards.
So there is no chance to set transactions number to zero, thus, shutting journal
may be blocked .
ocfs2_commit_thread()
ocfs2_commit_cache()
jbd2_journal_flush() -> failure takes journal into ABORT state, thus,
transaction number will never set to zero
The back trace is cited blow:
[<ffffffff8109de0c>] kthread_stop+0x4c/0x150
[<ffffffffc056a887>] ocfs2_journal_shutdown+0xa7/0x400 [ocfs2]
[<ffffffffc059fbde>] ocfs2_dismount_volume+0xbe/0x4a0 [ocfs2]
[<ffffffffc059fff7>] ocfs2_put_super+0x37/0xb0 [ocfs2]
[<ffffffff8120534e>] generic_shutdown_super+0x7e/0x110
[<ffffffff81205410>] kill_block_super+0x30/0x80
[<ffffffff81205669>] deactivate_locked_super+0x59/0x90
[<ffffffff812062ee>] deactivate_super+0x4e/0x70
[<ffffffff81222423>] cleanup_mnt+0x43/0x90
[<ffffffff812224c2>] __cleanup_mnt+0x12/0x20
[<ffffffff8109c247>] task_work_run+0xb7/0xf0
[<ffffffff81016f7c>] do_notify_resume+0x8c/0xa0
[<ffffffff817f8384>] int_signal+0x12/0x17
[<ffffffffffffffff>] 0xffffffffffffffff
Through crash debug tool, It can seen that j_num_trans field is set to 2.
struct ocfs2_journal {
j_state = OCFS2_JOURNAL_IN_SHUTDOWN,
j_journal = 0xffff8800b4926000,
j_inode = 0xffff880122aba298,
j_osb = 0xffff880093caa000,
j_bh = 0xffff8800a09df888,
j_num_trans = {
counter = 0x2
},
j_lock = {
{
rlock = {
raw_lock = {
{
To solve this issue, I propose a patch. Any comments will be welcomed.
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.
Andrew Morton
2017-Jan-09 22:42 UTC
[Ocfs2-devel] [PATCH] ocfs2/journal: fix umount hang after flushing journal failure
On Sat, 7 Jan 2017 12:01:06 +0000 Gechangwei <ge.changwei at h3c.com> wrote:> Hi, > > 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. > > Once jbd2_journal_flush() fails, the journal will be marked as ABORT state inner JBD2. There is no way to come back afterwards. > > So there is no chance to set transactions number to zero, thus, shutting journal may be blocked . > > > ocfs2_commit_thread() > > ocfs2_commit_cache() > > jbd2_journal_flush() -> failure takes journal into ABORT state, thus, transaction number will never set to zero > > > The back trace is cited blow: > > [<ffffffff8109de0c>] kthread_stop+0x4c/0x150 > [<ffffffffc056a887>] ocfs2_journal_shutdown+0xa7/0x400 [ocfs2] > [<ffffffffc059fbde>] ocfs2_dismount_volume+0xbe/0x4a0 [ocfs2] > [<ffffffffc059fff7>] ocfs2_put_super+0x37/0xb0 [ocfs2] > [<ffffffff8120534e>] generic_shutdown_super+0x7e/0x110 > [<ffffffff81205410>] kill_block_super+0x30/0x80 > [<ffffffff81205669>] deactivate_locked_super+0x59/0x90 > [<ffffffff812062ee>] deactivate_super+0x4e/0x70 > [<ffffffff81222423>] cleanup_mnt+0x43/0x90 > [<ffffffff812224c2>] __cleanup_mnt+0x12/0x20 > [<ffffffff8109c247>] task_work_run+0xb7/0xf0 > [<ffffffff81016f7c>] do_notify_resume+0x8c/0xa0 > [<ffffffff817f8384>] int_signal+0x12/0x17 > [<ffffffffffffffff>] 0xffffffffffffffff > > Through crash debug tool, It can seen that j_num_trans field is set to 2. > > struct ocfs2_journal { > j_state = OCFS2_JOURNAL_IN_SHUTDOWN, > j_journal = 0xffff8800b4926000, > j_inode = 0xffff880122aba298, > j_osb = 0xffff880093caa000, > j_bh = 0xffff8800a09df888, > j_num_trans = { > counter = 0x2 > }, > j_lock = { > { > rlock = { > raw_lock = { > { > > > To solve this issue, I propose a patch. Any comments will be welcomed. > > 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. > > > From 98f42f5f52851ed84eb372a3e09a413a30ea2664 Mon Sep 17 00:00:00 2001 > From: gechangwei <ge.changwei at h3c.com><mailto:ge.changwei at h3c.com> > Date: Sat, 7 Jan 2017 19:48:13 +0800 > Subject: [PATCH] fix umount hang after flushing journal failure > > Signed-off-by: gechangwei <ge.changwei at h3c.com><mailto:ge.changwei at h3c.com> > --- > fs/ocfs2/journal.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c > index a244f14..dab2094 100644 > --- a/fs/ocfs2/journal.c > +++ b/fs/ocfs2/journal.c > @@ -326,6 +326,7 @@ static int ocfs2_commit_cache(struct ocfs2_super *osb) > status = jbd2_journal_flush(journal->j_journal); > jbd2_journal_unlock_updates(journal->j_journal); > if (status < 0) { > + atomic_set(&journal->j_num_trans, 0); > up_write(&journal->j_trans_barrier); > mlog_errno(status); > goto finally;This seems a little hacky, but I'll let the ocfs2 developers decide. I do think there should be a code comment here, telling readers why this operation is being performed.
Joseph Qi
2017-Jan-10 06:17 UTC
[Ocfs2-devel] [PATCH] ocfs2/journal: fix umount hang after flushing journal failure
According to the call trace, umount hangs because ocfs2_commit_thread can't exit. So I think we'd better put the logic into ocfs2_commit_thread, which can be align with kthread_should_stop to identify the case. Thanks, Joseph On 17/1/7 20:01, Gechangwei wrote:> > Hi, > > 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. > > Once jbd2_journal_flush() fails, the journal will be marked as ABORT > state inner JBD2. There is no way to come back afterwards. > > So there is no chance to set transactions number to zero, thus, > shutting journal may be blocked . > > > ocfs2_commit_thread() > > ocfs2_commit_cache() > > jbd2_journal_flush() -> failure takes journal into ABORT > state, thus, transaction number will never set to zero > > > The back trace is cited blow: > > [<ffffffff8109de0c>] kthread_stop+0x4c/0x150 > [<ffffffffc056a887>] ocfs2_journal_shutdown+0xa7/0x400 [ocfs2] > [<ffffffffc059fbde>] ocfs2_dismount_volume+0xbe/0x4a0 [ocfs2] > [<ffffffffc059fff7>] ocfs2_put_super+0x37/0xb0 [ocfs2] > [<ffffffff8120534e>] generic_shutdown_super+0x7e/0x110 > [<ffffffff81205410>] kill_block_super+0x30/0x80 > [<ffffffff81205669>] deactivate_locked_super+0x59/0x90 > [<ffffffff812062ee>] deactivate_super+0x4e/0x70 > [<ffffffff81222423>] cleanup_mnt+0x43/0x90 > [<ffffffff812224c2>] __cleanup_mnt+0x12/0x20 > [<ffffffff8109c247>] task_work_run+0xb7/0xf0 > [<ffffffff81016f7c>] do_notify_resume+0x8c/0xa0 > [<ffffffff817f8384>] int_signal+0x12/0x17 > [<ffffffffffffffff>] 0xffffffffffffffff > > Through crash debug tool, It can seen that j_num_trans field is set to 2. > > struct ocfs2_journal { > j_state = OCFS2_JOURNAL_IN_SHUTDOWN, > j_journal = 0xffff8800b4926000, > j_inode = 0xffff880122aba298, > j_osb = 0xffff880093caa000, > j_bh = 0xffff8800a09df888, > j_num_trans = { > counter = 0x2 > }, > j_lock = { > { > rlock = { > raw_lock = { > { > > > To solve this issue, I propose a patch. Any comments will be welcomed. > > 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. > > > From 98f42f5f52851ed84eb372a3e09a413a30ea2664 Mon Sep 17 00:00:00 2001 > From: gechangwei <ge.changwei at h3c.com> > Date: Sat, 7 Jan 2017 19:48:13 +0800 > Subject: [PATCH] fix umount hang after flushing journal failure > > Signed-off-by: gechangwei <ge.changwei at h3c.com> > --- > fs/ocfs2/journal.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c > index a244f14..dab2094 100644 > --- a/fs/ocfs2/journal.c > +++ b/fs/ocfs2/journal.c > @@ -326,6 +326,7 @@ static int ocfs2_commit_cache(struct ocfs2_super *osb) > status = jbd2_journal_flush(journal->j_journal); > jbd2_journal_unlock_updates(journal->j_journal); > if (status < 0) { > + atomic_set(&journal->j_num_trans, 0); > up_write(&journal->j_trans_barrier); > mlog_errno(status); > goto finally; > -- > 2.5.1.windows.1 > > > ------------------------------------------------------------------------------------------------------------------------------------- > ???????????????????????????????????????? > ???????????????????????????????????????? > ???????????????????????????????????????? > ??? > This e-mail and its attachments contain confidential information from > H3C, which is > intended only for the person or entity whose address is listed above. > Any use of the > information contained herein in any way (including, but not limited > to, total or partial > disclosure, reproduction, or dissemination) by persons other than the > intended > recipient(s) is prohibited. If you receive this e-mail in error, > please notify the sender > by phone or email immediately and delete it!-------------- next part -------------- An HTML attachment was scrubbed... URL: http://oss.oracle.com/pipermail/ocfs2-devel/attachments/20170110/51b7989e/attachment.html