Date: Wed, 22 Apr 2015 09:06:53 +1000
From: NeilBrown <neilb@suse.de>
To: Christoph Hellwig <hch@infradead.org>
Cc: David Howells <dhowells@redhat.com>, Chris Mason <clm@fb.com>,
        Al Viro <viro@ZenIV.linux.org.uk>, Josef Bacik <jbacik@fb.com>,
        David Sterba <dsterba@suse.cz>, linux-cachefs@vger.kernel.org,
        Dave Chinner <david@fromorbit.com>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 2/3] fscache/cachefiles: optionally use SEEK_DATA
 instead of ->bmap.
Message-ID: <20150422090653.35ad074c@notabene.brown>
In-Reply-To: <20150420094539.GA12622@infradead.org>
References: <20150420052558.26554.97143.stgit@notabene.brown>
	<20150420052752.26554.52672.stgit@notabene.brown>
	<20150420060818.GA32675@infradead.org>
	<20150420162700.3e69c7db@notabene.brown>
	<20150420094539.GA12622@infradead.org>
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On Mon, 20 Apr 2015 02:45:39 -0700 Christoph Hellwig <hch@infradead.org>
wrote:

> On Mon, Apr 20, 2015 at 04:27:00PM +1000, NeilBrown wrote:
> > A worthwhile goal, but I certainly wouldn't consider pursuing it until =
what I
> > have submitted so far as been accepted - let's not reject "good" while
> > waiting for "perfect".
>=20
> It's still broken.  You add conditional flag for the almost right
> (almost because the flag in the filesystem type needs to go)

Why does it have to go?  I suspect you have a reason, but I can't read your
mind.

>  while
> leaving the broken option th default.=20

You say it is broken, and yet people are using it and are having a degree of
success.

Surely the appropriate process is:
 - introduce a "better" option
 - examine each relevant filesystem and transition over to use the new opti=
on.
 - remove the "not so good" option.

I'm still at step 1.

>   So what you propose here is not
> good, it's at best just as bad as the old version because you don't
> remove broken code but add a lot more clutter at the same time.

What I propose is measurably better because it works with BTRFS now, and
there seems to be a reasonable path towards making to generally better if
someone cares enough to examine each filesystem.

So I still claim you are pushing back against "good" because you want
"perfect".

NeilBrown

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