bcachefs: Fix transaction path overflow in fiemap

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/fs.c

@@ -935,7 +935,8 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info,
 	bch2_trans_iter_init(&trans, &iter, BTREE_ID_extents,
 			     SPOS(ei->v.i_ino, start, snapshot), 0);
 
-	while ((k = bch2_btree_iter_peek(&iter)).k &&
+	while (!(ret = btree_trans_too_many_iters(&trans)) &&
+	       (k = bch2_btree_iter_peek(&iter)).k &&
 	       !(ret = bkey_err(k)) &&
 	       bkey_cmp(iter.pos, end) < 0) {
 		enum btree_id data_btree = BTREE_ID_extents;