RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes

From	Matthew Wilcox <mawilcox@microsoft.com>
Newsgroups	linux.kernel
Subject	RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes
Date	2016-09-10 10:00 +0200
Message-ID	<sfLmF-5Ko-3@gated-at.bofh.it> (permalink)
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From: Christoph Hellwig [mailto:hch@infradead.org]
> On Sat, Sep 10, 2016 at 07:33:18AM +0000, Matthew Wilcox wrote:
> > > caller specific is unaceptable.  That being said your idea doesn't
> > > sounds unreasonable, but will require a bit more work and has no
> > > real short-term need.
> >
> > So your proposal is to remove buffer_heads from ext2?
> 
> No, the proposal is to remove buffer_heads from XFS first, then GFS2 and then
> maybe others like ext4.  I'd like to remove buffer_heads from the DAX path for
> ext2 and ext4 entitrely for sure (and direct I/O next).

That's ... what I propose.  The only use of buffer_head in my proposal is to
communicate a single extent from the filesystem to the DAX core, and that
can equally well use an iomap.  Ross seems to think that converting the current
DAX code over to using iomap requires converting all of ext2 away from
buffer_head; are you saying he's wrong?

Thread

Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-09-09 18:50 +0200
  RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-09 22:40 +0200
    Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Dan Williams <dan.j.williams@intel.com> - 2016-09-10 00:40 +0200
      Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Christoph Hellwig <hch@infradead.org> - 2016-09-10 09:40 +0200
        RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-10 10:00 +0200
        Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Theodore Ts'o <tytso@mit.edu> - 2016-09-10 20:00 +0200
          RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-11 02:50 +0200
      RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-10 10:20 +0200
        Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Dan Williams <dan.j.williams@intel.com> - 2016-09-10 17:00 +0200
    Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Christoph Hellwig <hch@infradead.org> - 2016-09-10 09:40 +0200
      RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-10 09:40 +0200
        Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Christoph Hellwig <hch@infradead.org> - 2016-09-10 09:50 +0200
          RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-10 10:00 +0200
            Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Christoph Hellwig <hch@infradead.org> - 2016-09-11 14:50 +0200
              Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-09-12 01:00 +0200
      RE: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Matthew Wilcox <mawilcox@microsoft.com> - 2016-09-10 18:00 +0200

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