Date: Sat, 13 Jun 2009 12:34:52 +0200
From: Pierre Ossman <pierre@ossman.eu>
To: dsaxena@plexity.net
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] MMC: Add 400ms to CAFE SD controller resume path
Message-ID: <20090613123452.0d24ec82@mjolnir.ossman.eu>
In-Reply-To: <20090604233349.GA2545@plexity.net>
References: <20090513200556.GA7882@plexity.net>
	<20090522135150.7e0716d6@mjolnir.ossman.eu>
	<20090528013629.0173522b.akpm@linux-foundation.org>
	<20090528104823.0a551ecb@mjolnir.ossman.eu>
	<20090604233349.GA2545@plexity.net>
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On Thu, 4 Jun 2009 23:33:49 +0000
Deepak Saxena <dsaxena@plexity.net> wrote:

>=20
> The request is not ending up in the queue of the new device.  If I=20
> recall correctyl What is happening is that userspace does an unmount on t=
he=20
> old device when it receives the notification that it is gone (since it is=
 not=20
> redected and a new entry is created). By the time that unmount is called,=
 the=20
> various data structures for the device has been zeroed out but the variou=
s=20
> operation pointers are !NULL, so when we go back to write the superblock =
for=20
> the mounted partition, we overwrite the device's partition table as the
> partition offset is now 0. The main issue here is that the kernel is allo=
wing=20
> an I/O to a device that is technically still there but not from the kerne=
l's
> POV.

But if the device is not there from the kernel's POV then it should be
impossible to write to it. It seems this is a kernel bug though. See
this thread:

http://marc.info/?t=3D124413860500006&r=3D1&w=3D2

Rgds
--=20
     -- Pierre Ossman

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