linux-ext4 - Re: [PATCH REBASED 0/7] ext4: Cleanup data=journal writeback path

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Date:   Fri, 3 Mar 2023 10:29:39 +0100
From:   Jan Kara <jack@...e.cz>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Jan Kara <jack@...e.cz>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH REBASED 0/7] ext4: Cleanup data=journal writeback path

On Thu 02-03-23 08:37:35, Theodore Ts'o wrote:
> On Tue, Feb 28, 2023 at 02:58:54PM +0100, Jan Kara wrote:
> > 
> > Regarding the warning somehow there are dirty pages left after the
> > procedures freeze_super() goes through to flush all dirty data. That is not
> > too surprising since in data=journal mode pages get (as a surprise to
> > freezing code) dirtied when transaction commits. I thought we have this
> > covered by jbd2_journal_flush() call in ext4_freeze() but maybe there are
> > some stranded PageDirty bits left? It needs more debugging...
> 
> So the question I have is whether this is a bug that was always there,
> or perhaps code changes affected the timing, so that it was much more
> likely to happen (although in my testing it's still only triggering
> about 50% of the time).
> 
> This warning can mean that data can be lost, especially if someone was
> doing hibernation, right?  We can discuss this at today's ext4 video
> conference, but I'm inclined to wait until the next merge cycle for
> this patch series until we can figure out what's going on.  Jan, what
> do you think?

As we discussed in the meeting, I'll have a look into the failure. For now
I'd keep patches on hold as it is not urgent patchset.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR