From: Dave Chinner <david@fromorbit.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Josef Bacik <jbacik@fusionio.com>,
lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org
Subject: Re: [ATTEND] [LSF TOPIC] What to do about O_DIRECT?
Date: Mon, 21 Jan 2013 09:35:21 +1100 [thread overview]
Message-ID: <20130120223521.GE2498@dastard> (raw)
In-Reply-To: <20130118230128.GA15758@thunk.org>
On Fri, Jan 18, 2013 at 06:01:28PM -0500, Theodore Ts'o wrote:
> .... and can we get rid of this horrible hack where we have this
> bastardized use of a struct buffer_head which is allocated on the
> stack, which has nothing really to do with a buffer head, and is all
> about the fact that no one wants to change the function signature for
> get_block_t?
I have patches to do that, but they are on the back burner right now
because it causes some kind of weird corruption in the pwritev case
that kvm uses to issue IO (i.e. large iovecs of 4k segments).
IMO, the direct IO code is that complex and convoluted now that t is
close to impossible to modify without introduce some weird, subtle
and almost impossible to debug issue. The code has been optimised to
the point of being unmaintainable, and I have seriously considered
just reimplementing the bits XFS needs just for XFS several times in
the past year....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2013-01-20 22:35 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-18 22:10 [ATTEND] [LSF TOPIC] What to do about O_DIRECT? Josef Bacik
2013-01-18 22:49 ` Zach Brown
2013-01-18 23:01 ` Theodore Ts'o
2013-01-20 22:35 ` Dave Chinner [this message]
2013-01-21 14:35 ` Josef Bacik
2013-01-22 14:03 ` Jan Kara
2013-01-30 23:16 ` Dave Chinner
2013-01-31 22:41 ` Jan Kara
2013-02-05 21:51 ` Dave Chinner
2013-02-06 0:40 ` Joel Becker
2013-02-06 4:32 ` Kent Overstreet
2013-02-06 17:36 ` Jan Kara
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