From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wouter van Heyst Subject: Bug#504391: [PATCH] mmc: add module parameter to set whether cards are assumed removable Date: Sun, 22 Nov 2009 12:42:35 +0100 Message-ID: <20091122114234.GA28590@one.lan> References: <1257914676.2237.57.camel@localhost> <20091116122329.847916b6.akpm@linux-foundation.org> <1258410709.2792.9.camel@localhost> Reply-To: Wouter van Heyst , 504391@bugs.debian.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Resent-To: debian-bugs-dist@lists.debian.org Resent-Message-ID: Content-Disposition: inline In-Reply-To: <1258410709.2792.9.camel@localhost> List-Post: List-Help: List-Subscribe: List-Unsubscribe: To: Ben Hutchings Cc: Andrew Morton , linux-mmc@vger.kernel.org, LKML , 504391@bugs.debian.org, Pierre Ossman List-Id: linux-mmc@vger.kernel.org On Mon, Nov 16, 2009 at 10:31:49PM +0000, Ben Hutchings wrote: > On Mon, 2009-11-16 at 12:23 -0800, Andrew Morton wrote: > > On Wed, 11 Nov 2009 04:44:36 +0000 > > Ben Hutchings wrote: > > > > > Some people run general-purpose distribution kernels on netbooks with > > > a card that is physically non-removable or logically non-removable > > > (e.g. used for /home) and cannot be cleanly unmounted during suspend. > > > Add a module parameter to set whether cards are assumed removable or > > > non-removable, with the default set by CONFIG_MMC_UNSAFE_RESUME. > > > > > > > The description really doesn't give me enough info to work out what's > > happening here and why this is being proposed. But it smells nasty. > > 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. 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. I'm running 2.6.32-rc7 with this patch applied and CONFIG_MMC_UNSAFE_RESUME=y That works as desired for my non-removable case. Is it desired that I test if 'removable=1' will thrash my filesystem? Wouter van Heyst