Message-ID: <4FE1F564.6070107@redhat.com>
Date: Wed, 20 Jun 2012 12:08:04 -0400
From: Rik van Riel <riel@redhat.com>
MIME-Version: 1.0
To: Mel Gorman <mgorman@suse.de>
CC: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>,
        Linux-Netdev <netdev@vger.kernel.org>,
        Linux-NFS <linux-nfs@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        David Miller <davem@davemloft.net>,
        Trond Myklebust <Trond.Myklebust@netapp.com>,
        Neil Brown <neilb@suse.de>, Christoph Hellwig <hch@infradead.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Mike Christie <michaelc@cs.wisc.edu>,
        Eric B Munson <emunson@mgebm.net>
Subject: Re: [PATCH 04/12] mm: Add support for a filesystem to activate swap
 files and use direct_IO for writing swap pages
References: <1340185081-22525-1-git-send-email-mgorman@suse.de> <1340185081-22525-5-git-send-email-mgorman@suse.de>
In-Reply-To: <1340185081-22525-5-git-send-email-mgorman@suse.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Sender: linux-nfs-owner@vger.kernel.org

On 06/20/2012 05:37 AM, Mel Gorman wrote:
> Currently swapfiles are managed entirely by the core VM by using ->bmap
> to allocate space and write to the blocks directly. This effectively
> ensures that the underlying blocks are allocated and avoids the need
> for the swap subsystem to locate what physical blocks store offsets
> within a file.
>
> If the swap subsystem is to use the filesystem information to locate
> the blocks, it is critical that information such as block groups,
> block bitmaps and the block descriptor table that map the swap file
> were resident in memory. This patch adds address_space_operations that
> the VM can call when activating or deactivating swap backed by a file.
>
>    int swap_activate(struct file *);
>    int swap_deactivate(struct file *);

Acked-by: Rik van Riel<riel@redhat.com>