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

From	Christoph Hellwig <hch@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes
Date	2016-08-30 09:30 +0200
Message-ID	<sbLEB-1Kt-5@gated-at.bofh.it> (permalink)
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On Mon, Aug 29, 2016 at 08:57:41AM -0400, Theodore Ts'o wrote:
> It's been on my todo list.  The only reason why I haven't done it yet
> is because I knew you were working on a solution, and I didn't want to
> do things one way for buffered I/O, and a different way for Direct
> I/O, and disentangling the DIO code and the different assumptions of
> how different file systems interact with the DIO code is a *mess*.

It is.  I have an almost working iomap direct I/O implementation, which
simplifies a lot of this.  Partially because it expects sane locking
(a shared lock should be held over read, fortunately we now have i_rwsem
for that) and allows less opt-in/out behavior, and partially just
because we have so much better infrastructure now (iomap, bio chaining,
iov_iters, ...).

The iomap version is still work in progress, but I'm about to post
a cut down version for block devices which reduces I/O latency by
20%.

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Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Ross Zwisler <ross.zwisler@linux.intel.com> - 2016-08-26 23:40 +0200
  Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Dave Chinner <david@fromorbit.com> - 2016-08-29 02:50 +0200
  Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Christoph Hellwig <hch@infradead.org> - 2016-08-29 10:10 +0200
    Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Theodore Ts'o <tytso@mit.edu> - 2016-08-29 15:00 +0200
      Re: [PATCH v2 2/9] ext2: tell DAX the size of allocation holes Christoph Hellwig <hch@infradead.org> - 2016-08-30 09:30 +0200

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