Date: Wed, 7 Feb 2007 10:05:00 -0200
From: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
To: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Andrew Morton <akpm@linux-foundation.org>, akuster@mvista.com,
       linux-kernel@vger.kernel.org, Pavel Machek <pavel@ucw.cz>,
       "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [patch 1/1] PM: Adds remount fs ro at suspend
Message-ID: <20070207120500.GF8148@khazad-dum.debian.net>
References: <20070202235132.EDBDF1C448@hermes.mvista.com> <20070202161611.cf8b4328.akpm@linux-foundation.org> <20070203003536.GA619@khazad-dum.debian.net> <1170710913.6105.39.camel@nigel.suspend2.net> <20070206143231.GD18392@khazad-dum.debian.net> <1170797924.14398.19.camel@nigel.suspend2.net> <20070207112539.GD8148@khazad-dum.debian.net> <1170848593.9827.24.camel@nigel.suspend2.net>
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On Wed, 07 Feb 2007, Nigel Cunningham wrote:
> > We don't cope okay with the power going out, at all.  And as an user case, a
> > need for fsck if you do something that is a reasonable use case (unplugging
> > devices while suspended) is not okay, either.
> 
> Maybe it depends on the filesystem you use. I've used ext3 for 6 or so
> years of development on Suspend2, and it's never given me a single
> problem, despite the fact that I've sometimes done the equivalent of
> pulling the plug without a sync or unmount. I did try XFS at one stage.
> It's performance was better, but it did give problems. Nevertheless, I'm
> more than happy to make the above claim about ext3.

XFS comes to mind, indeed. But as I said, a need for fsck and unclean
partitions are enough to label it as an "unsuitable" solution.

> > > Likewise with changes in hardware. Once hotplugging support is mature,
> > > suspending, switching around hardware and resuming should just result in
> > > hot[un]plug events.
> > 
> > Well, if we add *move* events for when someone unplugs a usb stick in one
> > port and replugs it in another while the system is in lala-land... maybe :-)
> > It would be normal to do it, when dealing with docks.
> 
> Isn't that part of the point to having those uuid thingys? I hate them
> at the moment (from the point of view of suspend code), but hopefully
> they'll end up being nicer to deal with.

When you have files open for writing (thus neither mount R/O or umount will
suceed)?   No, you really need kernel support for this, and yes, I imagine
it is a royal pain to deal with these cases, they clearly belong on the "20%
of stuff that causes 80% of the work" side :-)

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh
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