[Gluster-devel] Proposal to change locking in data-self-heal

[Stephan von Krawczynski]

On Tue, 21 May 2013 10:30:46 -0400
Jeff Darcy <jdarcy at redhat.com> wrote:

> On 05/21/2013 10:10 AM, Stephan von Krawczynski wrote:
> > See it as a corner case of a configurable option like:
> >
> > self-heal-chunksize = X
> > 128k < X < (unsigned)-1 (meaning all bits 1, don't know how many you have
> > here :-)
> 
> Unfortunately that doesn't quite work because a whole-file lock covers more 
> than just the data bits - i.e. inode information including size.  Really it's 
> more like there are two locks, but the second (inode) is always taken 
> concurrently with the first (data).  Maybe what we need to do is actually treat 
> it as two locks, similar to the approach Pranith suggested but where truncate 
> also interacts with the non-data lock.  This approach would also be more 
> consistent with the data/metadata distinction we make for a changelog, reducing 
> the number of permutations we have to consider.

My suggestion was thought as a user-configurable switch and corresponding
values. I didn't mean it as implementation proposal. Of course the real
implementation should deal with caveats not transparent to configuration or
the user per se.

-- 
Regards,
Stephan