From: Pavel Machek <pavel@ucw.cz>
To: Theodore Ts'o <tytso@mit.edu>, Matt Sealey <matt@genesi-usa.com>,
Mike Thompson <mpthompson@gmail.com>,
Shawn Guo <shawn.guo@linaro.org>,
Linux-Arm-Kernel <linux-arm-kernel@lists.infradead.org>,
linux-ext4@vger.kernel.org, linux-mmc@vger.kernel.org,
linux-kernel@vger.kernel.org, "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: Tracking down suspend/resume ext3/mmc issues on imx233
Date: Sat, 22 Sep 2012 21:59:13 +0200 [thread overview]
Message-ID: <20120922195912.GA25644@elf.ucw.cz> (raw)
In-Reply-To: <20120920000110.GA16672@thunk.org>
Hi!
On Wed 2012-09-19 20:01:10, Theodore Ts'o wrote:
> On Thu, Sep 20, 2012 at 01:23:49AM +0200, Pavel Machek wrote:
> >
> > I'm not sure I agree.
> >
> > If you treat root fs as removable, you'll get "crash". You'll need to
> > replay the journal, but data is safe.
> >
> > If you treat it as non-removable, and someone manages to remove it,
> > mount, and reinsert, you'll get silent data corruption.
>
> We could detect this case; if the file system gets mounted, the last
> mount time will change. So one of the things we could do is have the
> file system code freeze the file system at suspend time, so the file
> system is consistent (which will reduce the probability of data loss
> if the system never comes back up after the suspend), and save the
> last mount time and last write time in memory. When the system comes
> back from resume, have the file system code check the last mount and
> last write time, and if they have changed, it can refuse the resume
> and abort the system to avoid data corruption. It would require
> making ext3/ext4 suspend-aware, but it would be doable, if we really
> wanted to support this.
Yes please; I'd love to see this done.
We used to do sync() to get filesystem in consistent state, and I
believe that these days we are doing filesystem freeze; but code
validating the last mount time is certainly missing.
Looking forward,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
prev parent reply other threads:[~2012-09-22 19:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAEOSq-O3SfuAEhMsjX1y1ZgQuWBKef+XZzMR1b4yJhKhaRdymA@mail.gmail.com>
2012-09-07 6:05 ` Tracking down suspend/resume ext3/mmc issues on imx233 Shawn Guo
2012-09-08 16:17 ` Mike Thompson
2012-09-10 15:11 ` Matt Sealey
2012-09-10 16:33 ` Theodore Ts'o
2012-09-19 23:23 ` Pavel Machek
2012-09-20 0:01 ` Theodore Ts'o
2012-09-22 19:59 ` Pavel Machek [this message]
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