Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps)

From	Nicholas Piggin <npiggin@gmail.com>
Newsgroups	linux.kernel
Subject	Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps)
Date	2016-09-12 10:10 +0200
Message-ID	<sgutt-Fd-39@gated-at.bofh.it> (permalink)
References	<seZi1-15I-15@gated-at.bofh.it> <sfgsz-3pz-85@gated-at.bofh.it> <sgrYB-7wi-3@gated-at.bofh.it> <sgtQJ-ct-1@gated-at.bofh.it> <sgujL-mJ-3@gated-at.bofh.it>
Organization	IBM

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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.

Thread

Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Christoph Hellwig <hch@infradead.org> - 2016-09-12 07:30 +0200
  Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps) "Oliver O'Halloran" <oohall@gmail.com> - 2016-09-12 09:30 +0200
    Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Christoph Hellwig <hch@infradead.org> - 2016-09-12 10:00 +0200
      Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-12 10:10 +0200
        Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Christoph Hellwig <hch@infradead.org> - 2016-09-12 17:10 +0200
          Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-13 03:40 +0200
            Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in /proc/self/smaps) Dan Williams <dan.j.williams@intel.com> - 2016-09-13 06:10 +0200
              Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-13 07:50 +0200
        Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Dave Chinner <david@fromorbit.com> - 2016-09-12 23:40 +0200
          Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-13 04:00 +0200
            Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Christoph Hellwig <hch@infradead.org> - 2016-09-13 09:20 +0200
              Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-13 11:10 +0200
            Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Dave Chinner <david@fromorbit.com> - 2016-09-14 09:40 +0200
              Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-14 12:20 +0200
                Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Dave Chinner <david@fromorbit.com> - 2016-09-15 04:40 +0200
                Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-15 06:00 +0200
                Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Dave Chinner <david@fromorbit.com> - 2016-09-15 12:40 +0200
                Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-15 13:50 +0200
                Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Dave Chinner <david@fromorbit.com> - 2016-09-16 00:40 +0200
                Re: DAX mapping detection (was: Re: [PATCH] Fix region lost in  /proc/self/smaps) Nicholas Piggin <npiggin@gmail.com> - 2016-09-16 08:00 +0200

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