Re: [RFC][PATCH] PM / Sleep: Freeze filesystems during systemsuspend/hibernation
From: Alan Stern
Date: Wed Feb 01 2012 - 10:29:46 EST
On Wed, 1 Feb 2012, Pavel Machek wrote:
> > particular, this should help to solve a long-standing issue that, in
> > some cases, during resume from hibernation the boot loader causes the
> > journal to be replied for the filesystem containing the kernel image
> > and/or initrd causing it to become inconsistent with the information
> > stored in the hibernation image.
> Ungood. Why is bootloader/initrd doing that? If it mounts filesystem
> read/write, what is the guarantee that it will not change data on the
> filesystem, breaking stuff?
> Bootloaders should just not replay journals.
> > The user-space-driven hibernation (s2disk) is not covered by this
> > change, because the freezing of filesystems prevents s2disk from
> > accessing device special files it needs to do its job.
> ...so bootloaders need to be fixed, anyway.
I don't know about bootloaders, but from what I've heard, Linux fs
drivers (including those inside initrds) always replay the journal,
even if the filesystem is mounted read-only. This could be considered
a bug in the filesystem code.
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