Re: [patch 1/1] PM: Adds remount fs ro at suspend

From: Pavel Machek <pavel@ucw.cz>
To: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	akuster@mvista.com, linux-kernel@vger.kernel.org,
	"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [patch 1/1] PM: Adds remount fs ro at suspend
Date: Tue, 13 Feb 2007 13:12:13 +0100	[thread overview]
Message-ID: <20070213121213.GI18101@elf.ucw.cz> (raw)
In-Reply-To: <20070206143231.GD18392@khazad-dum.debian.net>

Hi!

> > Why do you think remounting filesystems is necessary? Are you getting
> > problems with some particular filesystem?
> 
> No.  But anything in a removable device neets to be either remounted
> read-only or unmounted if that is at all possible, because the user could
> unplug it.  It is of course, sync'd anyway, so if the remount/umount fails,
> no corruption should happen...  but the fs will be dirty, etc.
> 
> It can get very ugly when you factor in docks and removable bays. It's not
> just USB/firewire mass-storage devices and memory cards.  And there is the
> patological cases where the user suspends with the device in one port, and
> resumes with the device in another port.
> 
> I feel userspace *can* do all that needs to be done, but we are (currently)
> very bad at it.

Fix it in userspace, then. fsck when you unplug disk while suspended
should serve as a reminder to fix that userspace :-).

(And yes, you may need some kernel support to do it nicely; hopefully
same kernel support that will solve users unplugging disks without
umount.)
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html