From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Date: Tue, 14 Jul 2020 13:00:11 +0200
Subject: [Cluster-devel] [PATCH 2/2] iomap: fall back to buffered writes
 for invalidation failures
In-Reply-To: <20200713115509.GW12769@casper.infradead.org>
References: <20200713074633.875946-1-hch@lst.de>
	<20200713074633.875946-3-hch@lst.de>
	<20200713115509.GW12769@casper.infradead.org>
Message-ID: <20200714110011.GB16178@lst.de>
List-Id: <cluster-devel.redhat.com>
To: cluster-devel.redhat.com
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

On Mon, Jul 13, 2020 at 12:55:09PM +0100, Matthew Wilcox wrote:
> On Mon, Jul 13, 2020 at 09:46:33AM +0200, Christoph Hellwig wrote:
> > Failing to invalid the page cache means data in incoherent, which is
> > a very bad state for the system.  Always fall back to buffered I/O
> > through the page cache if we can't invalidate mappings.
> 
> Is that the right approach though?  I don't have a full picture in my head,
> but wouldn't we be better off marking these pages as !Uptodate and doing
> the direct I/O?

Isn't that a problem if e.g. pages are mapped into userspace and mlocked?