btrfs: remove redundant level reset in btrfs_del_items()

When btrfs_del_items() empties a leaf, it deletes the leaf unless it's
the root node. For the root leaf case, the code used to reset its level
to 0 via btrfs_set_header_level(). This is redundant as leaf nodes
always have level == 0.

Remove the unnecessary level assignment and invert the conditional to
handle only the non-root leaf deletion. The root leaf is correctly left
as-is.

No functional change.

Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: SaltyKitkat

fs/btrfs/ctree.c

@@ -4520,9 +4520,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 
 	/* delete the leaf if we've emptied it */
 	if (nritems == 0) {
-		if (leaf == root->node) {
-			btrfs_set_header_level(leaf, 0);
-		} else {
+		if (leaf != root->node) {
 			btrfs_clear_buffer_dirty(trans, leaf);
 			ret = btrfs_del_leaf(trans, root, path, leaf);
 			if (ret < 0)