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From: Christoph Hellwig <hch@lst.de>
To: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>,
	linux-nvdimm@lists.01.org, darrick.wong@oracle.com,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Ross Zwisler <zwisler@kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	lczerner@redhat.com, linux-ext4 <linux-ext4@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch
Date: Mon, 6 Aug 2018 17:49:43 +0200	[thread overview]
Message-ID: <20180806154943.GA17666@lst.de> (raw)
In-Reply-To: <20180806035550.GE7395@dastard>

> > > This allows the direct I/O path to do I/O and raise & lower page->_refcount
> > > while we're executing a truncate/hole punch.  This leads to us trying to free
> > > a page with an elevated refcount.
> 
> I don't see how this is possible in XFS - maybe I'm missing
> something, but "direct IO submission during truncate" is not
> something that should ever be happening in XFS, DAX or not.

The pages involved in a direct I/O are not that of the file that
the direct I/O read/write syscalls are called on, but those of the
memory regions the direct I/O read/write syscalls operate on.
Those pages could be file backed and undergo a truncate at the
same time.
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  reply	other threads:[~2018-08-06 15:44 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10 19:10 [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch Ross Zwisler
2018-07-10 19:10 ` [PATCH v4 1/2] dax: dax_layout_busy_page() warn on !exceptional Ross Zwisler
2018-08-10 19:52   ` Eric Sandeen
2018-08-10 20:33     ` Theodore Y. Ts'o
2018-08-11  2:10       ` Theodore Y. Ts'o
2018-08-13 10:12         ` Jan Kara
2018-08-13 12:46           ` Theodore Y. Ts'o
2018-08-24 15:44           ` Jan Kara
2018-08-27 16:09           ` Jan Kara
2018-07-10 19:10 ` [PATCH v4 2/2] ext4: handle layout changes to pinned DAX mappings Ross Zwisler
2018-07-11  8:17 ` [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch Jan Kara
2018-07-11 15:41   ` Ross Zwisler
2018-07-25 22:28   ` Ross Zwisler
2018-07-27 16:28     ` Ross Zwisler
2018-08-06  3:55       ` Dave Chinner
2018-08-06 15:49         ` Christoph Hellwig [this message]
2018-08-06 22:25           ` Dave Chinner
2018-08-07  8:45       ` Jan Kara
2018-09-10 22:18         ` Eric Sandeen
2018-09-11 15:14           ` Jan Kara
2018-09-11 15:20             ` Jan Kara
2018-09-11 17:28               ` Theodore Y. Ts'o
2018-09-11 18:21                 ` Eric Sandeen
2018-07-31 19:44 ` Ross Zwisler

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