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Date: Mon, 6 Apr 2009 17:19:31 -0400
From: Theodore Tso <tytso@mit.edu>
To: Hua Zhong <hzhong@gmail.com>
Cc: "'Linus Torvalds'" <torvalds@linux-foundation.org>,
       "'Jens Axboe'" <jens.axboe@oracle.com>,
       "'Linux Kernel Mailing List'" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/8][RFC] IO latency/throughput fixes
Message-ID: <20090406211931.GB8586@mit.edu>
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On Mon, Apr 06, 2009 at 01:12:08PM -0700, Hua Zhong wrote:
> Grr..making writeback as default would break people's setup that relies on
> the ordered semantics, especially in the embedded world. It's a big no-no.

I've added workarounds for 2.6.30 that provide the replace-via-rename
and replace-via-truncate workarounds for ext3 data=writeback cases.
See commits e7c8f507 and f7ab34ea.  

There won't be an implied fsync for newly created files, yes, but you
could have crashed 5 seconds earlier, at which point you would have
lost the newly created file anyway.  Replace-via-rename and
replace-via-truncate solves the problem for applications which are
editing pre-existing files, which was most of people's complaints
about depending on data=ordered semantics.

						- Ted
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