Re: Hibernation considerations

david
2007-07-16T00:00:20Z

On Sun, 15 Jul 2007, Alan Stern wrote:

> On Sun, 15 Jul 2007 david@lang.hm wrote:
>
>>> (1) Filesystems mounted before the hibernation are untouchable
>>>
>>> When there's a memory snapshot, either in the form of a hibernation image,
>>> or in the form of the "old" kernel and processes available to the "new"
>>> kexeced kernel responsible for saving their memory, the filesystems mounted
>>> before the hibernation should not be accessed, even for reading, because
>>> that would cause their on-disk state to be inconsistent with the snapshot
>>> and might lead to a filesystem corruption.
>>
>> AFAIK this is only the case with ext3, all other filesystems could be
>> accessed read-only safely
>>
>> this is arguably a bug with ext3 (and has been discussed as such), but
>> right now the ext3 team has decided not to change this bahavior so
>> hibernate needs to work around it. but don't mistake a work-around for a
>> single (admittedly very popular) filesystem with a hard and fast
>> directive.
>
> Isn't is possible to avoid this problem by mounting an ext3 filesystem
> as readonly ext2? Provided the filesystem isn't dirty it should be
> doable. (And provided the filesystem doesn't use any ext3 extensions
> that are incompatible with ext2.)

from the last discussion I saw on the kernel mailing list, no. the act of
mounting the ext3 filesystem as ext2 read-only will change it as the
unsupported extentions get turned off (and I think the journal contents at
least are lost as part of this)

David Lang