Btrfs devel - Jul 2008 - [RFC][PATCH] Fix nodatacow check

Hello,

This patch fixes the nodatacow check. The new test function can always
detect extents referenced by multiple snatshots. If a extent was
allocated in recent two transactions and no snapshot happened in these
two transactions, we can always avoid cow. To check given extent''s
reference, the test function walks down old tree root, then check
backref info in the path. This initial version takes old tree root
from root->commit. A new version using the oldest tree root will be
sent later.

Regards
YZ

On Fri, 2008-07-18 at 10:13 +0800, Yan Zheng wrote:
> Hello,
> 
> This patch fixes the nodatacow check. The new test function can always
> detect extents referenced by multiple snatshots. If a extent was
> allocated in recent two transactions and no snapshot happened in these
> two transactions, we can always avoid cow.
Thanks Yan, I think this should work.  Could you please update it to the
latest unstable tree and resend?

-chris


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