tree cce26617905afa50fd19066971f215baa4a19ca3
parent 7f518ad0a212e2a6fd68630e176af1de395070a7
author Joe Thornber <ejt@redhat.com> 1439388729 +0100
committer Mike Snitzer <snitzer@redhat.com> 1439391037 -0400

dm btree: add ref counting ops for the leaves of top level btrees

When using nested btrees, the top leaves of the top levels contain
block addresses for the root of the next tree down.  If we shadow a
shared leaf node the leaf values (sub tree roots) should be incremented
accordingly.

This is only an issue if there is metadata sharing in the top levels.
Which only occurs if metadata snapshots are being used (as is possible
with dm-thinp).  And could result in a block from the thinp metadata
snap being reused early, thus corrupting the thinp metadata snap.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org