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Date: Thu, 1 Mar 2012 11:42:01 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Kara <jack@suse.cz>
Cc: Fengguang Wu <fengguang.wu@intel.com>, Greg Thelen <gthelen@google.com>,
        Ying Han <yinghan@google.com>,
        "hannes@cmpxchg.org" <hannes@cmpxchg.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
        Minchan Kim <minchan.kim@gmail.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/9] writeback: introduce the pageout work
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On Thu, 1 Mar 2012 12:04:04 +0100
Jan Kara <jack@suse.cz> wrote:

> > iirc, the way I "grabbed" the page was to actually lock it, with
> > [try_]_lock_page().  And unlock it again way over within the writeback
> > thread.  I forget why I did it this way, rather than get_page() or
> > whatever.  Locking the page is a good way of preventing anyone else
> > from futzing with it.  It also pins the inode, which perhaps meant that
> > with careful management, I could avoid the igrab()/iput() horrors
> > discussed above.
>
>   I think using get_page() might be a good way to go.

get_page() doesn't pin the inode - truncate() will still detach it
from the address_space().