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Date:   Tue, 9 Apr 2019 14:15:09 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Jan Kara <jack@suse.cz>
Cc:     Andreas Gruenbacher <agruenba@redhat.com>,
        Christoph Hellwig <hch@lst.de>,
        cluster-devel <cluster-devel@redhat.com>,
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        Edwin =?iso-8859-1?B?VPZy9ms=?= <edvin.torok@citrix.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>, linux-mm@kvack.org
Subject: Re: gfs2 iomap dealock, IOMAP_F_UNBALANCED
Message-ID: <20190409121508.GA9532@lst.de>
References: <20190321131304.21618-1-agruenba@redhat.com> <20190328165104.GA21552@lst.de> <CAHc6FU49oBdo8mAq7hb1greR+B1C_Fpy5JU7RBHfRYACt1S4wA@mail.gmail.com> <20190407073213.GA9509@lst.de> <CAHc6FU7kgm4OyrY-KRb8H2w6LDrWDSJ2p=UgZeeJ8YrHynKU2w@mail.gmail.com> <20190408134405.GA15023@quack2.suse.cz>
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On Mon, Apr 08, 2019 at 03:44:05PM +0200, Jan Kara wrote:
> > We won't be able to do a log flush while another transaction is
> > active, but that's what's needed to clean dirty pages. iomap doesn't
> > allow us to put the block allocation into a separate transaction from
> > the page writes; for that, the opposite to the page_done hook would
> > probably be needed.
> 
> I agree that a ->page_prepare() hook would be probably the cleanest
> solution for this.

That doesn't sound too bad to me.