From: Jan Kara <jack@suse.cz>
Subject: Re: [Cluster-devel] fallocate vs O_(D)SYNC
Date: Wed, 16 Nov 2011 16:57:55 +0100
Message-ID: <20111116155755.GA22284@quack.suse.cz>
References: <20111116084256.GA22963@infradead.org>
 <1321436588.2713.5.camel@menhir>
 <20111116105413.GA2916@quack.suse.cz>
 <20111116124550.GA11650@infradead.org>
 <20111116133915.GD8195@quack.suse.cz>
 <20111116134234.GA24258@infradead.org>
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Cc: Jan Kara <jack@suse.cz>, Steven Whitehouse <swhiteho@redhat.com>,
	linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org,
	mfasheh@suse.com, jlbec@evilplan.org, cluster-devel@redhat.com
To: Christoph Hellwig <hch@infradead.org>
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In-Reply-To: <20111116134234.GA24258@infradead.org>
Sender: linux-ext4-owner@vger.kernel.org

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.

									Honza