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Date:   Tue, 21 Apr 2020 18:29:10 +0200
From:   Jan Kara <jack@suse.cz>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Dave Chinner <david@fromorbit.com>,
        Ritesh Harjani <riteshh@linux.ibm.com>,
        bugzilla-daemon@bugzilla.kernel.org, linux-ext4@vger.kernel.org,
        Theodore Ts'o <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        linux-fsdevel@vger.kernel.org
Subject: Re: [Bug 207367] Accraid / aptec / Microsemi / ext4 / larger then
 16TB
Message-ID: <20200421162910.GB5118@quack2.suse.cz>
References: <bug-207367-13602@https.bugzilla.kernel.org/>
 <bug-207367-13602-zdl9QZH6DN@https.bugzilla.kernel.org/>
 <20200421042039.BF8074C046@d06av22.portsmouth.uk.ibm.com>
 <20200421050850.GB27860@dread.disaster.area>
 <20200421080405.GA4149@infradead.org>
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On Tue 21-04-20 01:04:05, Christoph Hellwig wrote:
> On Tue, Apr 21, 2020 at 03:08:50PM +1000, Dave Chinner wrote:
> > > 4. fs/jbd2/journal.c
> > 
> > Broken on filesystems where the journal file might be placed beyond
> > a 32 bit block number, iomap_bmap() just makes that obvious. Needs
> > fixing.
> 
> I think this wants to use iomap, as that would solve all the problems.

Well, there are two problems with this - firstly, ocfs2 is also using jbd2
and it knows nothing about iomap. So that would have to be implemented.
Secondly, you have to somehow pass iomap ops to jbd2 so it all boils down
to passing some callback to jbd2 during journal init to map blocks anyway
as Dave said. And then it is upto filesystem to do the mapping - usually
directly using its internal block mapping function - so no need for iomap
AFAICT.
								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR