From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
Dave Chinner <david@fromorbit.com>, Jens Axboe <axboe@kernel.dk>,
linux-fsdevel@vger.kernel.org,
linux-ext4 <linux-ext4@vger.kernel.org>
Subject: Re: BLKZEROOUT + pread should return zeroes, right?
Date: Thu, 16 Oct 2014 13:04:15 -0700 [thread overview]
Message-ID: <20141016200415.GA16637@birch.djwong.org> (raw)
In-Reply-To: <yq1iojm6rti.fsf@sermon.lab.mkp.net>
On Tue, Oct 14, 2014 at 09:32:25PM -0400, Martin K. Petersen wrote:
> >>>>> "Darrick" == Darrick J Wong <darrick.wong@oracle.com> writes:
>
> Darrick> Well then let's change BLKZEROOUT to require O_DIRECT instead
> Darrick> of hiding the coherency problem,
>
> That would break existing users, though.
<shrug> If they're using the existing BLKZEROOUT without O_DIRECT they're
already broken.
But I might as well just fix them quietly.
--D
> Darrick> A further optimization to mke2fs would be to detect that we've
> Darrick> run discard-with-zeroes and therefore can skip issuing
> Darrick> subsequent zeroouts on the same ranges, but I'm wary that
> Darrick> discard-zeroes-data does what it purports to do.
>
> It's dubious. I'm working on making sure we only set discard_zeroes_data
> when the device guarantees it for 3.19.
>
> --
> Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2014-10-16 20:04 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 [this message]
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
2014-10-15 1:02 ` Martin K. Petersen
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