Re: [dm-devel] Re: Was: [patch 1/1] md/dm: Reduce stack usage with stacked block devices

[Ming Zhang <mingz ele uri edu>]

On Wed, 2006-01-11 at 21:26 +0100, Molle Bestefich wrote:
> Alasdair G Kergon wrote:
> > There are several races.  The code makes some ordering assumptions
> > about the I/O but does nothing to enforce those assumptions.
> > So if you're unlucky and I/O happens to complete in the wrong order
> > or too soon you can see transient corruption in the snapshot or
> > reference memory that has been freed and perhaps reallocated to
> > something else.
> 
> Thanks a lot for the status report.
> 
> > Some references:
> [snip]
> 
> Thanks.  I opened a bug report myself at one point:
> https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=120937
> 
> > Not actively developed, no.  Long-term we want to replace it with
> > something better.

does this mean/confirm linux 2.6.x will not have a stable snapshot
support any time soon?

i believe tons of people want linux has a stable snapshot support.

> 
> That's really too bad :-(.
> There's a lot of people over in the Xen community that could *really*
> use something like dm-snapshot if it was stable and production mature.
> 
> > But at the moment I'm reviewing the existing code
> > and fixing as many problems as I can find.
> 
> Sounds great.  Shout out if you need help :-).
> (With testing or other monkey work, not C coding.  I'm not a good C coder.)
> 
> Thanks!
> 
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