linux-kernel - Re: [RFC][PATCH] PM / Sleep: Freeze filesystems during system suspend/hibernation

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Message-ID: <20131218140842.GA20488@amd.pavel.ucw.cz>
Date:	Wed, 18 Dec 2013 15:08:42 +0100
From:	Pavel Machek <pavel@....cz>
To:	Dave Chinner <david@...morbit.com>
Cc:	Josh Boyer <jwboyer@...oraproject.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, Jan Kara <jack@...e.cz>,
	linux-fsdevel@...r.kernel.org,
	Nigel Cunningham <nigel@...onice.net>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: Re: [RFC][PATCH] PM / Sleep: Freeze filesystems during system
 suspend/hibernation

> > > I disagree - given the problem it is resolving leads to silent
> > > filesystem corruption, this patch should be considered somewhat of a
> > > priority to push...
> > 
> > Umm. Ok, I forgot what it does, really.
> 
> It ensures that the filesystem is in an quiescent state both in
> memory and on disk, and it cannot be modified in memory or on disk
> whilst the suspend image is being generated, or by log recovery
> after a resume before the suspended image has been restored.

If someone attempts to run log recovery before resume, that's a bug
and yes, it will corrupt filesystems. (Including ext3). Don't do that.

Documentation/power/swsusp.txt:

 * BIG FAT WARNING
   *********************************************************
 *
 * If you touch anything on disk between suspend and resume...
 *                              ...kiss your data goodbye.

> > So... for few years now suspend corrupts data on XFS? And Fedora has
> > the fix but it is not in mainline? That does not sound right...
> 
> The issues freezing the filesystem before the suspend image is
> created affect every journalled filesystem linux supports, be
> it XFS, ext4, reiser, btrfs, etc.

Did not it have some problems with ext3?

Regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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