Btrfs: many allocator fixes, pretty solid

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/TODO b/fs/btrfs/TODO
index 6a8c8cd..f6df246 100644
--- a/fs/btrfs/TODO
+++ b/fs/btrfs/TODO
@@ -7,6 +7,7 @@
 * Get rid of struct ctree_path, limiting tree levels held at one time
 * Add generation number to key pointer in nodes
 * Add generation number to inode
+* Add ability to switch a block group from data to metadata or vice versa
 * Release
 * Do real tree locking
 * Add extent mirroring (backup copies of blocks)