tree d541e61440f06f37d17e2d14cbaa78fc0cd41ff2
parent a970b0a16cc416a509d5ae8b1d70978664e6f4fe
author Yan Zheng <zheng.yan@oracle.com> 1246151255 -0400
committer Chris Mason <chris.mason@oracle.com> 1246556477 -0400

Btrfs: update backrefs while dropping snapshot

The new backref format has restriction on type of backref item.  If a tree
block isn't referenced by its owner tree, full backrefs must be used for the
pointers in it. When a tree block loses its owner tree's reference, backrefs
for the pointers in it should be updated to full backrefs. Current
btrfs_drop_snapshot misses the code that updates backrefs, so it's unsafe for
general use.

This patch adds backrefs update code to btrfs_drop_snapshot.  It isn't a
problem in the restricted form btrfs_drop_snapshot is used today, but for
general snapshot deletion this update is required.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>