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From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mmc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	504391@bugs.debian.org,
	Wouter van Heyst <larstiq@larstiq.dyndns.org>,
	Pierre Ossman <pierre@ossman.eu>
Subject: Re: [PATCH] mmc: add module parameter to set whether cards are assumed removable
Date: Tue, 17 Nov 2009 08:53:00 +0100	[thread overview]
Message-ID: <4B02565C.1030406@s5r6.in-berlin.de> (raw)
In-Reply-To: <1258410709.2792.9.camel@localhost>

Ben Hutchings wrote:
> In general, it is not possible to tell whether a card present in an MMC
> slot after resume is the same that was there before suspend.

That's true for virtually all storage devices, not just MMC.

> So there are two possible behaviours, each of which will cause data
> loss in some cases:
> 
> CONFIG_MMC_UNSAFE_RESUME=n (default): Cards are assumed to be removed
> during suspend.  Any filesystem on them must be unmounted before
> suspend; otherwise, buffered writes will be lost.
> 
> CONFIG_MMC_UNSAFE_RESUME=y: Cards are assumed to remain present during
> suspend.  They must not be swapped during suspend; otherwise, buffered
> writes will be flushed to the wrong card.
> 
> Currently the choice is made at compile time and this allows that to be
> overridden at module load time.

Can't the kernel flush the write buffer at suspend time, so that you can
remove this choice for good?
-- 
Stefan Richter
-=====-==--= =-== =---=
http://arcgraph.de/sr/

  reply	other threads:[~2009-11-17  7:53 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-11  4:44 [PATCH] mmc: add module parameter to set whether cards are assumed removable Ben Hutchings
2009-11-16 20:23 ` Andrew Morton
2009-11-16 22:31   ` Ben Hutchings
2009-11-17  7:53     ` Stefan Richter [this message]
2009-11-30 12:39       ` Pierre Ossman
2009-11-30 12:54         ` Alan Cox
2009-11-30 13:09           ` Pierre Ossman
2009-11-30 13:32         ` Maxim Levitsky
2009-11-30 13:51           ` Alan Cox
2009-11-30 15:27             ` Maxim Levitsky
2009-11-22 11:42     ` Bug#504391: " Wouter van Heyst
2009-11-22 12:32       ` Ben Hutchings
2009-12-01 19:57         ` Wouter van Heyst
2009-11-30 12:38 ` Adrian Hunter
2009-11-30 12:48   ` Alan Cox

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