Btrfs: Add lowest key information to back refs for extent tree blocks as well.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 5b1f90f..1cc4d28 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -545,13 +545,10 @@
 			u64 disk_num_bytes = 0;
 			u64 extent_num_bytes = 0;
 			u64 root_gen;
+			u64 root_owner;
 
-			if (leaf != root->node) {
-				root_gen =
-					btrfs_header_generation(path->nodes[1]);
-			} else {
-				root_gen = btrfs_header_generation(leaf);
-			}
+			root_gen = btrfs_header_generation(leaf);
+			root_owner = btrfs_header_owner(leaf);
 			if (found_extent) {
 				disk_bytenr =
 				      btrfs_file_extent_disk_bytenr(leaf,
@@ -575,7 +572,7 @@
 				ret = btrfs_free_extent(trans, root,
 						disk_bytenr,
 						disk_num_bytes,
-						root->root_key.objectid,
+						root_owner,
 						root_gen, inode->i_ino,
 						key.offset, 0);
 			}