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From: Nicholas Piggin <npiggin@gmail.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Oliver O'Halloran <oohall@gmail.com>,
	Yumei Huang <yuhuang@redhat.com>, Michal Hocko <mhocko@suse.com>,
	Xiao Guangrong <guangrong.xiao@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	KVM list <kvm@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
	Gleb Natapov <gleb@kernel.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
	mtosatti@redhat.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps)
Date: Mon, 12 Sep 2016 18:05:07 +1000	[thread overview]
Message-ID: <20160912180507.533b3549@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <20160912075128.GB21474@infradead.org>

On Mon, 12 Sep 2016 00:51:28 -0700
Christoph Hellwig <hch@infradead.org> wrote:

> On Mon, Sep 12, 2016 at 05:25:15PM +1000, Oliver O'Halloran wrote:
> > What are the problems here? Is this a matter of existing filesystems
> > being unable/unwilling to support this or is it just fundamentally
> > broken?  
> 
> It's a fundamentally broken model.  See Dave's post that actually was
> sent slightly earlier then mine for the list of required items, which
> is fairly unrealistic.  You could probably try to architect a file
> system for it, but I doubt it would gain much traction.

It's not fundamentally broken, it just doesn't fit well existing
filesystems.

Dave's post of requirements is also wrong. A filesystem does not have
to guarantee all that, it only has to guarantee that is the case for
a given block after it has a mapping and page fault returns, other
operations can be supported by invalidating mappings, etc.

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  reply	other threads:[~2016-09-12  8:05 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-08  4:32 DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps) Dan Williams
2016-09-08 22:56 ` Ross Zwisler
2016-09-08 23:04   ` Dan Williams
2016-09-09  8:55     ` Xiao Guangrong
2016-09-09 15:40       ` Dan Williams
2016-09-12  6:00         ` Xiao Guangrong
2016-09-12  3:44       ` Rudoff, Andy
2016-09-12  6:31         ` Xiao Guangrong
2016-09-12  1:40   ` Dave Chinner
2016-09-15  5:55     ` Darrick J. Wong
2016-09-15  6:25       ` Dave Chinner
2016-09-12  5:27   ` Christoph Hellwig
2016-09-12  7:25     ` Oliver O'Halloran
2016-09-12  7:51       ` Christoph Hellwig
2016-09-12  8:05         ` Nicholas Piggin [this message]
2016-09-12 15:01           ` Christoph Hellwig
2016-09-13  1:31             ` Nicholas Piggin
2016-09-13  4:06               ` Dan Williams
2016-09-13  5:40                 ` Nicholas Piggin
2016-09-12 21:34           ` Dave Chinner
2016-09-13  1:53             ` Nicholas Piggin
2016-09-13  7:17               ` Christoph Hellwig
2016-09-13  9:06                 ` Nicholas Piggin
2016-09-14  7:39               ` Dave Chinner
2016-09-14 10:19                 ` Nicholas Piggin
2016-09-15  2:31                   ` Dave Chinner
2016-09-15  3:49                     ` Nicholas Piggin
2016-09-15 10:32                       ` Dave Chinner
2016-09-15 11:42                         ` Nicholas Piggin
2016-09-15 22:33                           ` Dave Chinner
2016-09-16  5:54                             ` Nicholas Piggin
2016-12-19 21:11                               ` Ross Zwisler
2016-12-20  1:09                                 ` Darrick J. Wong
2016-12-20  1:18                                   ` Dan Williams
2016-12-21  0:40                                     ` Darrick J. Wong
2016-12-21 16:53                                       ` Dan Williams
2016-12-21 21:24                                         ` Dave Chinner
2016-12-21 21:33                                           ` Dan Williams

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