From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd@arndb.de>
Subject: Re: Proposal to improve filesystem/block snapshot interaction
Date: Tue, 30 Oct 2007 17:37:27 +0100
Message-ID: <200710301737.29007.arnd@arndb.de>
References: <20070927063113.GD2989@sgi.com> <7fe698080710300719ne3ff2b0wb4ebd8ffd75a288a@mail.gmail.com> <20071030153707.GC13455@lazybastard.org>
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Cc: Dongjun Shin <djshin90@gmail.com>, Greg Banks <gnb@sgi.com>,
	Linux Filesystem Mailing List <linux-fsdevel@vger.kernel.org>,
	David Chinner <dgc@melbourne.sgi.com>,
	Donald Douwsma <donaldd@melbourne.sgi.com>,
	Christoph Hellwig <hch@infradead.org>,
	Roger Strassburg <rls@sgi.com>, Mark Goodwin <markgw@sgi.com>,
	Brett Jon Grandbois <brettg@melbourne.sgi.com>
To: =?utf-8?q?J=C3=B6rn_Engel?= <joern@logfs.org>
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On Tuesday 30 October 2007, J=C3=B6rn Engel wrote:
> On Tue, 30 October 2007 23:19:48 +0900, Dongjun Shin wrote:
> > On 10/30/07, Arnd Bergmann <arnd@arndb.de> wrote:
> > >
> > > Not sure. Why shouldn't you be able to reorder the hints provided=
 that
> > > they don't overlap with read/write bios for the same block?
> >=20
> > You're right. The bios can be reordered if they don't overlap with =
hint.
>=20
> I would keep things simpler. =C2=A0Bios can be reordered, full stop. =
=C2=A0If an
> erase and a write overlap, the caller (filesystem?) has to add a
> barrier.

I thought bios were already ordered if they affect the same blocks.
Either way, I agree that an erase should not be treated special on
the bio layer, its ordering should be handled the same way we do it
for writes.

	Arnd <><
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