From: Dave Chinner <david@fromorbit.com>
To: Zach Brown <zab@zabbo.net>
Cc: Christoph Hellwig <hch@infradead.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Jens Axboe <axboe@kernel.dk>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-fsdevel@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>,
linux-ext4 <linux-ext4@vger.kernel.org>
Subject: Re: BLKZEROOUT + pread should return zeroes, right?
Date: Wed, 15 Oct 2014 07:21:47 +1100 [thread overview]
Message-ID: <20141014202147.GI17506@dastard> (raw)
In-Reply-To: <20141014185753.GA6838@lenny.home.zabbo.net>
On Tue, Oct 14, 2014 at 11:57:53AM -0700, Zach Brown wrote:
> On Tue, Oct 14, 2014 at 02:21:28AM -0700, Christoph Hellwig wrote:
> > On Tue, Oct 14, 2014 at 03:27:11PM +1100, Dave Chinner wrote:
> > > Broken usage, IMO. If you are going to use the block layer ioctls to
> > > manipulate data int eh block device, you should be using direct Io
> > > for all your data IO to the block device. Otherwise, coherency
> > > problems occur....
> >
> > I'd say BLKZEROOUT semantics are broken. Having an ioctl exposed
> > that maniulates on-disk data without cache coherence is a nightmare
> > that people trip over easily. Even experienced people like Darrick.
>
> I'm definitely with Christoph on this one. Coherent writes should be
> the norm.
I don't care what happens to the block layer ioctls w.r.t. cache
coherency. If people want to make them fully cache coherent for
buffered IO, go right ahead.
But that doesn't change the fact that if you want your application
to work sanely on existing kernels, then using direct IO is the only
option...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2014-10-14 20:21 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-14 3:01 BLKZEROOUT + pread should return zeroes, right? Darrick J. Wong
2014-10-14 4:27 ` Dave Chinner
2014-10-14 6:02 ` Darrick J. Wong
2014-10-14 6:32 ` Theodore Ts'o
2014-10-15 1:25 ` Darrick J. Wong
2014-10-15 1:32 ` Martin K. Petersen
2014-10-16 20:04 ` Darrick J. Wong
2014-10-15 10:02 ` Theodore Ts'o
2014-10-15 12:09 ` Martin K. Petersen
2014-10-18 0:03 ` [RFC PATCH] block: make BLKZEROOUT invalidate page cache contents Darrick J. Wong
2014-10-14 9:21 ` BLKZEROOUT + pread should return zeroes, right? Christoph Hellwig
2014-10-14 13:44 ` Martin K. Petersen
2014-10-14 18:57 ` Zach Brown
2014-10-14 20:21 ` Dave Chinner [this message]
2014-10-15 1:02 ` Martin K. Petersen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141014202147.GI17506@dastard \
--to=david@fromorbit.com \
--cc=axboe@kernel.dk \
--cc=darrick.wong@oracle.com \
--cc=hch@infradead.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=tytso@mit.edu \
--cc=zab@zabbo.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).