bcachefs: Make BTREE_ITER_IS_EXTENTS private to iter code

Prep work for changing the core btree update path to handle extents like
regular keys; we need to reduce the scope of what BTREE_ITER_IS_EXTENTS
means
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -408,7 +408,7 @@ static void __bch2_btree_iter_verify(struct btree_iter *iter,
 	 * For extents, the iterator may have skipped past deleted keys (but not
 	 * whiteouts)
 	 */
-	k = b->c.level || iter->flags & BTREE_ITER_IS_EXTENTS
+	k = b->c.level || btree_node_type_is_extents(iter->btree_id)
 		? bch2_btree_node_iter_prev_filter(&tmp, b, KEY_TYPE_discard)
 		: bch2_btree_node_iter_prev_all(&tmp, b);
 	if (k && bkey_iter_pos_cmp(b, k, &pos) >= 0) {
@@ -563,7 +563,7 @@ static void __bch2_btree_node_iter_fix(struct btree_iter *iter,
 	if (!bch2_btree_node_iter_end(node_iter) &&
 	    iter_current_key_modified &&
 	    (b->c.level ||
-	     (iter->flags & BTREE_ITER_IS_EXTENTS))) {
+	     btree_node_type_is_extents(iter->btree_id))) {
 		struct bset_tree *t;
 		struct bkey_packed *k, *k2, *p;
 

fs/bcachefs/btree_update_leaf.c

@@ -780,7 +780,7 @@ int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 
 	iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 
-	if (iter->flags & BTREE_ITER_IS_EXTENTS) {
+	if (btree_node_type_is_extents(iter->btree_id)) {
 		iter->pos_after_commit = k->k.p;
 		iter->flags |= BTREE_ITER_SET_POS_AFTER_COMMIT;
 	}
@@ -898,7 +898,7 @@ int bch2_btree_delete_at_range(struct btree_trans *trans,
 		 */
 		delete.k.p = iter->pos;
 
-		if (iter->flags & BTREE_ITER_IS_EXTENTS) {
+		if (btree_node_type_is_extents(iter->btree_id)) {
 			unsigned max_sectors =
 				KEY_SIZE_MAX & (~0 << trans->c->block_bits);