From: Brendan Hide <brendan@swiftspirit.co.za>
Subject: Re: [PATCH v2 5/5] btrfs: enable swap file support
Date: Tue, 25 Nov 2014 07:55:34 +0200
Message-ID: <547419D6.40905@swiftspirit.co.za>
References: <cover.1416563833.git.osandov@osandov.com> <afd3c1009172a4a1cfa10e73a64caf35c631a6d4.1416563833.git.osandov@osandov.com> <20141121180045.GF8568@twin.jikos.cz> <20141122200357.GA15189@mew> <20141124220302.GA5785@mew.dhcp4.washington.edu>
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Cc: Filipe David Manana <fdmanana@gmail.com>,
 David Sterba <dsterba@suse.cz>,
 linux-btrfs@vger.kernel.org, Alexander Viro <viro@zeniv.linux.org.uk>,
 Andrew Morton <akpm@linux-foundation.org>,
 Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
 linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-mm@kvack.org, linux-nfs@vger.kernel.org,
 Trond Myklebust <trond.myklebust@primarydata.com>,
 Mel Gorman <mgorman@suse.de>
To: Omar Sandoval <osandov@osandov.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <20141124220302.GA5785@mew.dhcp4.washington.edu>
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On 2014/11/25 00:03, Omar Sandoval wrote:
> [snip]
>
> The snapshot issue is a little tricker to resolve. I see a few options:
>
> 1. Just do the COW and hope for the best
> 2. As part of btrfs_swap_activate, COW any shared extents. If a snapshot
> happens while a swap file is active, we'll fall back to 1.
> 3. Clobber any swap file extents which are in a snapshot, i.e., always use the
> existing extent.
>
> I'm partial to 3, as it's the simplest approach, and I don't think it makes
> much sense for a swap file to be in a snapshot anyways. I'd appreciate any
> comments that anyone might have.
>
Personally, 3 seems pragmatic - but not necessarily "correct". :-/

-- 
__________
Brendan Hide
http://swiftspirit.co.za/
http://www.webafrica.co.za/?AFF1E97

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