From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mikulas Patocka <mpatocka@redhat.com>
Subject: Re: [dm-devel] [PATCH] deadlock with suspend and quotas
Date: Wed, 30 Nov 2011 11:36:11 -0500 (EST)
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Cc: Jan Kara <jack@suse.cz>, esandeen@redhat.com,
	linux-kernel@vger.kernel.org, dm-devel@redhat.com,
	linux-fsdevel@vger.kernel.org,
	Christopher Chaltain <christopher.chaltain@canonical.com>,
	Valerie Aurora <val@vaaconsulting.com>
To: Alasdair G Kergon <agk@redhat.com>
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On Wed, 30 Nov 2011, Alasdair G Kergon wrote:

> On Wed, Nov 30, 2011 at 01:33:32PM +0000, Alasdair G Kergon wrote:
> > Have I missed something in this
> > reasoning, Mikulas?
>  
> Ah - counter-example: mmap?
> So sync might indeed be required to block on the filesystem iff there
> are newly-dirtied pages.
> 
> Alasdair

On non-journaled filesystem, both write and mmap can create dirty pages 
when suspended.

On ext4 I actually tested mmap, but it blocks any writes to mmaped pages 
while suspended.

Mikulas