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>
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index b23dc20..0083979 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1788,7 +1788,7 @@
btrfs_end_transaction(trans, root);
}
- btrfs_drop_dead_root(reloc_root);
+ btrfs_drop_snapshot(reloc_root, 0);
if (atomic_dec_and_test(async->num_pending))
complete(async->done);
@@ -2075,9 +2075,6 @@
ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
BUG_ON(ret);
-
- btrfs_tree_unlock(eb);
- free_extent_buffer(eb);
}
if (!lowest) {
btrfs_tree_unlock(upper->eb);