Re: [dm-devel] Barriers still not passing on simple dm devices...

[Alasdair G Kergon]

On Wed, Apr 08, 2009 at 09:27:20PM -0400, Chris Mason wrote:
> I'm afraid expecting barriers forever in the future isn't completely
> compatible with dm or md.  Both of these allow the storage to change
> over time, and the filesystem needs to handle this without corruptions.
 
The missing piece of the jigsaw is notification to upper layers *ahead*
of such reconfigurations.  (We have similar notification issues when
devices are resized - the current approach is to leave the sysadmin
responsible for co-ordinating changes through userspace.)

Alasdair
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