linux-ext4 - Re: [Cluster-devel] fallocate vs O

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Message-ID: <20111116193540.GL23779@wotan.suse.de>
Date:	Wed, 16 Nov 2011 11:35:40 -0800
From:	Mark Fasheh <mfasheh@...e.de>
To:	Chris Mason <chris.mason@...cle.com>, Jan Kara <jack@...e.cz>,
	Christoph Hellwig <hch@...radead.org>,
	Steven Whitehouse <swhiteho@...hat.com>,
	linux-btrfs@...r.kernel.org, linux-ext4@...r.kernel.org,
	jlbec@...lplan.org, cluster-devel@...hat.com
Subject: Re: [Cluster-devel] fallocate vs O_(D)SYNC

On Wed, Nov 16, 2011 at 11:18:06AM -0500, Chris Mason wrote:
> On Wed, Nov 16, 2011 at 04:57:55PM +0100, Jan Kara wrote:
> > On Wed 16-11-11 08:42:34, Christoph Hellwig wrote:
> > > On Wed, Nov 16, 2011 at 02:39:15PM +0100, Jan Kara wrote:
> > > > > This would work fine with XFS and be equivalent to what it does for
> > > > > O_DSYNC now.  But I'd rather see every filesystem do the right thing
> > > > > and make sure the update actually is on disk when doing O_(D)SYNC
> > > > > operations.
> > > >   OK, I don't really have a strong opinion here. Are you afraid that just
> > > > calling fsync() need not be enough to push all updates fallocate did to
> > > > disk?
> > > 
> > > No, the point is that you should not have to call fsync when doing
> > > O_SYNC I/O.  That's the whole point of it.
> >   I agree with you that userspace shouldn't have to call fsync. What I
> > meant is that sys_fallocate() or do_fallocate() can call
> > generic_write_sync(file, pos, len), and that would be completely
> > transparent to userspace.
> 
> We should do it per FS though, I'll patch up btrfs.

I agree about doing it per FS. Ocfs2 just needs a one-liner to mark the
journal transaction as synchronous.
	--Mark

--
Mark Fasheh
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