[Ocfs2-devel] [PATCH 2/2] ocfs2: add error handling path when jbd2 enter ABORT status

[Heming Zhao]

On Thu, May 04, 2023 at 10:27:46AM +0800, Joseph Qi wrote:
> 
> 
> On 4/30/23 11:13 AM, Heming Zhao wrote:
> > fstest generic cases 347 361 628 629 trigger a same issue:
> > When jbd2 enter ABORT status, ocfs2 ignores it and keep going to commit
> > journal.
> 
> What's the end user impact?

There are two impacts:

1. this issue makes unmount command hanging.

No one likes or accepts filesystem unmount failure when underlying devices meets
error. For comparison, other FSs (e.g. ext4, xfs, gfs2, ..) could do unmount
successfully.

2. for developers to verify their patch doesn't make any regression.

fstest is a famious & important fs testsuite.
(Yes, I know ocfs2 has itself testsuite ocfs2_test.)

Current status, there are many test cases (about 9 in my env) cause fstest
hanging and blocking fstest to run. I did test for gfs2 on latest tumbleweed,
gfs2 only has 1 hanging case.

In my view, ocfs2 developers or maintainers at least make ocfs2 to finish the
testsuite. Long-term target is to make ocfs2 to pass all the testsuite.

On kernel 6.2.9-1, the fstest 'quick' test group result:
(the result based on my two patches [1/2] & [2/2])
```
./check -g quick -T -b -s ocfs2 -e generic/081 -e generic/648

Failures: generic/003 generic/013 generic/015 generic/040 generic/041
generic/062 generic/082 generic/104 generic/107 generic/228 generic/244
generic/266 generic/272 generic/277 generic/281 generic/322 generic/329
generic/331 generic/336 generic/343 generic/376 generic/379 generic/380
generic/383 generic/384 generic/385 generic/386 generic/400 generic/410
generic/424 generic/441 generic/448 generic/449 generic/471 generic/479
generic/493 generic/495 generic/510 generic/537 generic/552 generic/563
generic/578 generic/594 generic/607 generic/620 generic/628 generic/630
generic/636 generic/702
Failed 49 of 568 tests
```

> 
> JBD2_ABORT indicates a fatal error happens, either in jounral layer or
> filesystem. And we should not commit any further transactions.
> It seems that we may unify the behavior like:
> 
> if (is_journal_aborted(journal))
> 	return -EROFS;
> 
> 
IIUC, do you mean add above code in ocfs2_commit_cache or in
ocfs2_commit_thread?
1>
If in ocfs2_commit_cache, this fix doesn't take any effect for unmount
failure(hanging).
When return -EROFS, the caller ocfs2_commit_thread just print error message and
keep going to retry.
2>
If in ocfs2_commit_thread, it makes commit thread exit/stop without notifying
other ocfs2 paths. Later wake_up(&osb->checkpoint_event) won't take effect,
ocfs2 will enter chaose. 

In my view, there is missing a place to set fs RO. So [2/2] in
ocfs2_commit_cache, uses ocfs2_error to mark RO before returning status (<0
value). The ocfs2_error is the right place to mark RO.

- Heming

> > 
> > This commit gives ocfs2 ability to handle jbd2 ABORT case.
> > 
> > Signed-off-by: Heming Zhao <heming.zhao at suse.com>
> > ---
> >  fs/ocfs2/alloc.c      | 10 ++++++----
> >  fs/ocfs2/journal.c    |  5 +++++
> >  fs/ocfs2/localalloc.c |  3 +++
> >  3 files changed, 14 insertions(+), 4 deletions(-)
> > 
> > diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
> > index 51c93929a146..d90961a1c433 100644
> > --- a/fs/ocfs2/alloc.c
> > +++ b/fs/ocfs2/alloc.c
> > @@ -6308,11 +6308,13 @@ void ocfs2_truncate_log_shutdown(struct ocfs2_super *osb)
> >  
> >  	if (tl_inode) {
> >  		cancel_delayed_work(&osb->osb_truncate_log_wq);
> > -		flush_workqueue(osb->ocfs2_wq);
> > +		if (!is_journal_aborted(osb->journal->j_journal)) {
> > +			flush_workqueue(osb->ocfs2_wq);
> >  
> > -		status = ocfs2_flush_truncate_log(osb);
> > -		if (status < 0)
> > -			mlog_errno(status);
> > +			status = ocfs2_flush_truncate_log(osb);
> > +			if (status < 0)
> > +				mlog_errno(status);
> > +		}
> >  
> >  		brelse(osb->osb_tl_bh);
> >  		iput(osb->osb_tl_inode);
> > diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> > index 25d8072ccfce..2798067a2f66 100644
> > --- a/fs/ocfs2/journal.c
> > +++ b/fs/ocfs2/journal.c
> > @@ -312,11 +312,16 @@ static int ocfs2_commit_cache(struct ocfs2_super *osb)
> >  	status = jbd2_journal_flush(journal->j_journal, 0);
> >  	jbd2_journal_unlock_updates(journal->j_journal);
> >  	if (status < 0) {
> > +		if (is_journal_aborted(journal->j_journal)) {
> > +			ocfs2_error(osb->sb, "jbd2 status: ABORT.\n");
> > +			goto reset;
> > +		}
> >  		up_write(&journal->j_trans_barrier);
> >  		mlog_errno(status);
> >  		goto finally;
> >  	}
> >  
> > +reset:
> >  	ocfs2_inc_trans_id(journal);
> >  
> >  	flushed = atomic_read(&journal->j_num_trans);
> > diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
> > index c4426d12a2ad..e2e3400717b0 100644
> > --- a/fs/ocfs2/localalloc.c
> > +++ b/fs/ocfs2/localalloc.c
> > @@ -378,6 +378,9 @@ void ocfs2_shutdown_local_alloc(struct ocfs2_super *osb)
> >  	if (osb->ocfs2_wq)
> >  		flush_workqueue(osb->ocfs2_wq);
> >  
> > +	if (is_journal_aborted(osb->journal->j_journal))
> > +		goto out;
> > +
> >  	if (osb->local_alloc_state == OCFS2_LA_UNUSED)
> >  		goto out;
> >