linux-kernel - Re: [PATCH v3 5/5] ext4: Defer mmap cmtime update until writeback

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Message-ID: <20130820040857.GI6023@dastard>
Date:	Tue, 20 Aug 2013 14:08:57 +1000
From:	Dave Chinner <david@...morbit.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Theodore Ts'o <tytso@....edu>,
	Dave Hansen <dave.hansen@...ux.intel.com>, xfs@....sgi.com,
	Jan Kara <jack@...e.cz>, Tim Chen <tim.c.chen@...ux.intel.com>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v3 5/5] ext4: Defer mmap cmtime update until writeback

On Mon, Aug 19, 2013 at 08:30:02PM -0700, Andy Lutomirski wrote:
> On Mon, Aug 19, 2013 at 7:38 PM, Dave Chinner <david@...morbit.com> wrote:
> > On Fri, Aug 16, 2013 at 04:22:12PM -0700, Andy Lutomirski wrote:
> >> A fancier implementation could probably avoid an extra journal
> >> transaction by adding a mapping_test_clear_cmtime call in
> >> ext4_writepages, but this should already be a considerable
> >> improvement -- we'll start one transaction per writepages call
> >> instead of one per page.
> >
> > I'd like to see more than just an ext4 implementation - btrfs and
> > XFS are the other main filesystems that should behave identically.
> 
> Will do.
> 
> >
> > Also, it's worthwhile to write a generic xfstest to ensure that they
> > all update the timestamp appropriately - if its' in xfstests, then
> > we can basically guarantee that it won't get randomly regressed in
> > future, and other filesystems can be easily verified as well sa
> > their implement this.
> >
> 
> Is there a guide to writing an xfstest?

Yes. see the readme file in the root directory of the repository.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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