btrfs: Go readonly on tree errors in balance_level

balace_level() seems to deal with missing tree nodes by BUG_ON(). Instead,
we can easily just set the file system readonly and bubble -EROFS back up
the stack.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 36e16bd..651a26a 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -944,7 +944,12 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
 
                /* promote the child to a root */
                child = read_node_slot(root, mid, 0);
-               BUG_ON(!child);
+               if (!child) {
+                       ret = -EROFS;
+                       btrfs_std_error(root->fs_info, ret);
+                       goto enospc;
+               }
+
                btrfs_tree_lock(child);
                btrfs_set_lock_blocking(child);
                ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
@@ -1042,7 +1047,11 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                 * otherwise we would have pulled some pointers from the
                 * right
                 */
-               BUG_ON(!left);
+               if (!left) {
+                       ret = -EROFS;
+                       btrfs_std_error(root->fs_info, ret);
+                       goto enospc;
+               }
                wret = balance_node_right(trans, root, mid, left);
                if (wret < 0) {
                        ret = wret;