btrfs: open code btrfs_backref_get_eb()

The helper is trivial, we can inline it. It's safe to remove the 'if' as
the iterator is always valid when used, the potential NULL was never
checked anyway.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/backref.c

@@ -2960,7 +2960,7 @@ int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
  */
 int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
 {
-	struct extent_buffer *eb = btrfs_backref_get_eb(iter);
+	struct extent_buffer *eb = iter->path->nodes[0];
 	struct btrfs_root *extent_root;
 	struct btrfs_path *path = iter->path;
 	struct btrfs_extent_inline_ref *iref;
@@ -3438,7 +3438,7 @@ int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans,
 		int type;
 
 		cond_resched();
-		eb = btrfs_backref_get_eb(iter);
+		eb = iter->path->nodes[0];
 
 		key.objectid = iter->bytenr;
 		if (btrfs_backref_iter_is_inline_ref(iter)) {

fs/btrfs/backref.h

@@ -283,14 +283,6 @@ struct btrfs_backref_iter {
 
 struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info);
 
-static inline struct extent_buffer *btrfs_backref_get_eb(
-		struct btrfs_backref_iter *iter)
-{
-	if (!iter)
-		return NULL;
-	return iter->path->nodes[0];
-}
-
 /*
  * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data
  * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header.